C O N V E N T I O N
HOSIEDByAie&GSA
PEfilHJESIEBNAUSIfiAllA
australian earth sciences convention PERTH CONVENTION EXHIBITION CENTRE
Sunday 20 July - Thursday 24 July, 2008
PROGRAM & ABSTRACT BOOKLET
Abstract No. 89
X
ifffi
As we pursue our vision for the 'mine of the future', we're partnering with leading researchers and investing in new technologies. Visit our exhibit at the Australian Earth Sciences Convention to see this cutting-edge technology in action. And for nnore on how we're changing the face of mining, visit www.riotinto.com.
TABLE OF CONTENTS 1 Welcome from the GSA & AIG Presidents Convention Convenors & Committee General Information Registration Desk Messages Exhibition Best Exhibitor Prize Catering Convention Sessions Program Changes Poster Sessions Speakers Preparation Internet Cafe Name Badges Mobile Phones Evaluation Prize Draw Parking at PCEC How to get to PCEC Bus Train Taxi Ferry Getting Around Perth Accommodation
8 8 8
Map of Perth (showing accommodation) Networking Program Ice Breaker Happy Hours Student Careers Night Geotrivia Night Convention Dinner
10 10 10 10 10 10
Business Meetings
10
Sponsors
11
Plenary Keynote Speakers
14
Program Monday 21 July 2008 Tuesday 22 July 2008 Wednesday 23 July 2008 Thursday 24 July 2008
18 18 20 22 24
Index of Presenters by Surname
26
Speaker & Poster Presenter Abstracts
38
Membership Application Forms - GSA & AIG
261
Exhibition Exhibitor Contact Details Exhibition Floor Plan
274 276
Australian Earth Sciences Convention 2008
Geological Society of Australia, ABSTRACTS No. 89 Australian Earth Science Convention 2008, Perth, Western Australia 19"'Australian Geological Convention
ISSN 0729 OllX © Geological Society of Australia Incorporated, 2000 j ^ Copies of this publication may be obtained from the Geological Society of Australia Incorporated, 301 George Street, Sydney, NSW, Australia 2000 This volume should be cited as: . . ^^^^ ^ ^ . „ . Geological Society of Australia and the Australian Institute of Geoscientists, 2008. Australian Earth Sciences Convention (AESC) 2008. New Generation Advances in Geoscience. Abstracts No 89 of the 19'" Australian Geological Convention, Perth Convention and Exhibition Centre, Perth WA, Australia. July 20 - 24, 276 pages.
WELCOME 3 from the AIG & GSA presidents
Dear CoUeA^. On behalf of the Geological Society of Australia (GSA) and the Australian Institute of Geoscientists (AIG), it is our pleasure to welcome you to Perth, Western Australia, to participate in the Australian Earth Sciences Convention (AESC) 2008. This is a joint celebration of the International Year of Planet Earth! We are delighted you could attend this major event on the international geosciences calendar and, at the same time, experience the stunning beauty of Western Australia and its unique and timeless geology - a landscape that makes this State a 'must see' destination for geoscientists from all walks of life. Western Australia is also home to a globally significant resources and energy industry which is heavily dependent on cutting-edge geoscientific data and technology. Over the next 4 days the Convention will deliver an extremely wide-ranging program featuring an outstanding selection of Australian and international speakers, industry leaders and key decision-makers. They will present the latest knowledge and innovative thinking in geosciences through a mix of keynote addresses, oral and poster presentations, and workshops. This will provide a valuable opportunity for you to meet, discuss and debate contemporary Earth Science issues with geoscientists and other Earth Science professionals from all comers of the geoscientific community - from those working in mining to those working in astronomy, from those in industry to those in government, research or academia.. .and everything in between! The Convention Organising Committee extends a very special welcome to our Australian and international speakers and presenters, who have all given their time generously to provide you with an excellent learning and networking opportunity. A big thank you must also go to our sponsors and exhibitors, whose financial support has greatly assisted in keeping attendance fees for the Convention to a minimum. Finally, we would like to thank the Convention Organising Committee whose strong commitment has made this convention possible. Many individuals have contributed enormously to the Committee and its various sub-committees. Thank you for choosing to attend the Australian Earth Sciences Convention 2008. We look forward to meeting you over the next few days and hope you will also enjoy the exciting social and networking events that complement this year's program.
Rick Rogerson AIG President
Andrew Gleadow GSA President
Australian Earth Sciences Convention 2008
NORILSK
NICKEL
STEP UP WITH NORILSK The Norilsk Nickel Group is the world's largest nickel producer with operations in Russia, Finland, Botswana, South Africa, USA and Australia. In Australia we have over 1,200 employees and contractors working with us across six sites in the Eastern Goldfields region and Perth. A significant growth phase means we can offer a range of rewarding geology careers in operations, projects and support roles. We foster a culture of performance, accountabilityand communication where you are supported in your professional development and will be recognised for your efforts. We can offer a choice of lifestyle options with both FIFO and Kalgoorlie residential operations. Our Perth opportunities offer careers in exploration and projects. To find out more about your career with Norilsk, please contact: Peter Danks, Human Resources Manager, Phone: +61 8 9426 0100 or visit comeandexplore.com
CONVENTION CONVENORS & COMMITTEE
Geological Society of Australia (GSA)
The Australian Institute of Geoscientists (AIG)
www.gsa.org.au
www.aig.org.au
The Geological Society of Australia was established as a non-profit organisation in 1952 to promote, advance and support Earth sciences in Australia.
The Australian Institute of Geoscientists AIG is a leading professional institute representing geoscientists in all professional sectors throughout Australia.
The Geological Society of Australia aims to: • cater for a wide diversity of members; • influence the decision making processes of government, particularly to support geoscience research and teaching; • encourage and promote wider community awareness and application of Earth sciences; • provide media and forums for communication in the Earth sciences.
AIG was formed in 1981 to help: • provide effective representation on issues affecting the status and perception of geoscience professions; • cooperate with other professional institutes on matters of common interest; • ensure the availability of diverse, educational opportunities for students at all levels; • develop and maintain standards for professional practice; • provide high quality, accessible, relevant short courses, seminars and conferences; • promote continued professional development by members; • enhance employment opportunities for geoscience professionals.
The Society's members represent all Earth Science professions, including geologists, geophysicists, geochemists, palaeontologists, hydrogeologists, geotechnical and engineering geologists, environmental geologists, and associated professions. Members come from the minerals and petroleum industries, government departments, research and education institutions and consultancy groups.
5
CONVENTION ORGANISING COMMITTEE
Ian Tyler Department of Industry and Resources, WA
Rick Rogerson Australian Institute of Geoscientists Finance Committee
Marcus F Harris Cryptodome Sponsorship & Exhibition Committee
Jon Hronsky Western Mining Services Convention's Program Director
Jocelyn Thomson Jaytee Commercial Enterprises Sponsorship & Exhibition and Workshops Committees
Sue Fletcher Geological Society of Australia, Chairperson, Steering Committee
Peter Cawood University of Western Australia
Ian Fitzsimons Curtin University of Technology
Philip Commander Tim Griffin Department of Water (WA) Department of Industry d Rescources, WA
Sandra Occhipinti AngloGold Ashanti Marketing Committee
Roger Hocking Department of Industry «fe Rescources, WA
CONVENTION ORGANISERS International Conferences & Events (ICE) Aust Pty Ltd Suite 4, 73 Hay Street, Subiaco, WA, 6008, Australia Tel: +61 8 9381 9281 / Fax: +61 8 9381 9560 Email: events@iceaustralia .com / Website: www.iceaustralia.com Otlices m Perth, Sydney, Melbourne and Brisbane
Australian Earlh Sdartcas Conventioo 2008
O F I E L. D S
Gold Fields Australia Gold Fields Limited is one of the world's largest unhedged producers of gold with production of 4 million ounces per annum, mineral reserves of 94 million ounces and mineral resources of 252 million ounces. We employ 47,000 employees across our operations with mining and exploration activity in Africa, North America, South America, Europe, Asia and Australia. Australian Operations St Ives Gold Mine is located 80 kilometres south of Kalgoorlie, near Lake Lefroy in the Eastern Goldfields region of Western Australia. The operation falls within the geological region known as the Archaean Norseman-Wiluna greenstone belt. St Ives takes its name from the largest of many small, historic workings scattered throughout the area, that of Ives Reward, which was discovered by prospector Pat Ives in 1919. Mining here was discontinued for many years and was resumed in 1981 by Western Mining Corporation (WMC) before being bought by Gold Fields in 2001. Agnew Gold Mine is located 375 kilometres north of Kalgoorlie. The Agnew deposit, in the same geological region as St Ives, was discovered in 1895. Mining by a variety of people and companies has continued off and on since then. WMC secured the leases early in the 1980s and started operating in 1986. What Gold Fields Australia has to offer: • • • • • • •
International operations S'" largest gold company in Australia 7 major contractors Your choice of residential (St Ives) - go home to family every night & become involved in community life or FIFO (Agnew) St Ives has 3 underground operations and 5 open pit mines all in one area - huge variety of experience and opportunity on one site! Diversity of opportunity Exciting, cutting edge technology
For information on our Company visit: www.goldfields.co.za To see our Australian employment opportunities visit: www.careers.goldfields.com.au
GENERAL INFORMATION 7 REGISTRATION DESK & SECRETARIAT
INTERNET CAFE
On arrival at the Convention, please proceed to the registration desk located on Level 1 at the Perth Convention Exhibition Centre.
Please feel free to take advantage of the AESC Internet cafe, located at the rear of the Exhibition Pavilion, and open to all delegates.
Hours of Operation: Sunday 20 July Monday 21 July Tuesday 22 July Wednesday 23 July Thursday 24 July
15.00-19.00 08.00 - 18.00 08.00 - 18.00 08.00 - 18.30 08.00 - 16.30
The convention secretariat will be located in Meeting Room 12.
MESSAGES Messages may be left at the convention registration desk. All messages will be posted on the board next to the registration desk. As no responsibility can be taken to deliver messages personally, please check this board at regular intervals.
EXHIBITION The Exhibition will run in Pavilion 1 and 2 on Level 1 of the Perth Convention Exhibition Centre (PCEC) during the following times: Exhibition Opening Times: Sunday 20 July 17.30 - 19.00 Monday 21 July 08.00 - 18.45 Tuesday 22 July 08.00 - 20.00 Wednesday 23 July 08.00 - 18.15 Thursday 24 July 08.00 - 14.15
NAME BADGES Delegates are required to wear their name badges at all times. You will not be authorised for entry into convention sessions, the exhibition area or provided access to lunches, morning and afternoon teas without your name badge.
MOBILE PHONES Please ensure your mobile phone is switched off or in 'silent' mode during all convention sessions.
EVALUATION PRIZE DRAW Delegates have a chance to win Western Australian wine by completing the AESC 2008 evaluation form. To go in the prize draw, please place your completed form in one of the receptacles sitting outside the Riverside Theatre between 16.00pm and 16.10pm on Thursday 24 July, as you make your way to the final convention session.
PARKING AT PCEC Parking within the PCEC compound is extremely limited and is on a first-come, first-served basis.
The winner of the Best Exhibitor Prize will be announced in the Best Paper and Poster Awards Session from 16.10pm to 16.45pm on Thursday 24 July.
The City of Perth owns and operates the car park at the PCEC. The car park is open 24 hours a day, 7 days a week except for maintenance and servicing. Fully-trained customer service staff are in attendance. Entry to the car park, that has 1,500 bays, is from the Mitchell Freeway and Mounts Bay Road. There are three exits - Mounts Bay Road, Mitchell Freeway and Riverside Drive.
CATERING
Alternatively, early bird parking or long stay parking is available at the following locations:
BEST EXHIBITOR PRIZE
Lunches, morning and afternoon teas will be held in the exhibition area throughout the convention, making it a true meeting point for delegates and a wonderful opportunity to network with them.
CONVENTION SESSIONS All plenary sessions will be held in the Rio Tinto Plenary Theatre on Level 2 of the PCEC. Concurrent sessions will be held in Meeting Rooms 1 - 10, on Level 2 of the PCEC.
• Wilson Parking Westralia Square (entry via Mounts Bay Road) Phone: 9321 3424 • Parmelia Hilton 14 Mill Street Phone: 9215 2413(concierge)
HOW TO GET TO PCEC
PROGRAM CHANGES
The PCEC can be easily accessed via bus, train, ferry and taxi.
Any changes to the program will be regularly updated and pasted on Program Signage next to the Registration Desk and throughout the convention venue. In addition, updates will be announced by chairpersons in sessions.
By Bus The Esplanade Busport is located adjacent to the PCEC with frequent service to the Perth metropolitan area. Upon your arrival take the stairs up to the Busport main deck and head south following the signs through to the PCEC's entrance.
POSTER SESSIONS Posters will be on display in the Exhibition area from 8.30am on Monday 21 July through to 14.15pm on Thursday 24 July. Authors have been asked to stand near their posters during lunch breaks to speak with delegates about their work and answer questions.
SPEAKERS PREPARATION This is located in Meeting Room 11 on Level 2 of the Perth Convention Exhibition Centre, just next to the Convention Secretariat.
Park 'n' Ride services are also available from Morley, Murdoch, Rockingham and Success. The Blue CAT operates a free circle route transportation service between the Busport and other major transport centres such as the Perth train station. By Train The Esplanade Train Station is right next to PCEC. In addition to the main Perth train station, Perth has two Metro Rail underground stations: William Street Platforms and the Esplanade station, which is next to the PCEC.
Australian Earth Sciences Convention 2008
8
GENERAL INFORMATION & ACCOMMODATION
The central Perth train station is only a 10-15 minute walk from the PCEC. If walking from the central Perth train station, head right along Wellington Street. Turn left down William Street and then turn right onto St Georges Terrace. Walking on the river side of St Georges Terrace and take a left through to Westralia Square (if you pass Mercantile Lane you've gone too far). By Taxi Inform your taxi driver to enter at the City of Perth car park entrance off Mounts Bay Road. Before actually going into the City of Perth Car park go to the left of the street lights. Keep to the left lane that goes directly in front of the Medina Hotel. (There is another lane that runs alongside the Plaza entry that is used for buses - do not use this lane.) The correct lane runs on the hotel side of a small white fence. Staying in this lane you will travel up underneath a small tunnel onto the Plaza of the PCEC. Exit from the Plaza is to the left on the loop road. (There is a sign indicating the exit point.) Taxis can be called to the Plaza for you upon your departure from the PCEC. By Ferry A ferry operates between Barrack St Jetty, Mend St Jetty, with limited services to Coode St Jetty.
GETTING AROUND PERTH For more information on TransPerth services and timetables call the TransPerth InfoLine on 13 62 13 (TTY: +61 8 9428 1999 for hearing impaired) or visit the website http://www.transperth.wa.gov.au.
ACCOMMODATION Parmelia Hilton 14 Mill Street, Perth Phone: 9215 2000
Perth Ambassador Hotel 196 Adelaide Terrace, Perth Phone: 9325 1455
Medina Grand 33 Mounts Bay Road, Perth Phone: 9217 8000
Goodearth Hotel, Perth 195 Adelaide Terrace, East Perth Phone: 9492 7777
Pacific International Suites 305 Murray Street, Perth Phone: 9347 7000
University of Western Australia Currie Hall Perth Winthrop Avenue, Crawley Phone: 9273 3333
Best Western Emerald Hotel 24 Mount Street, Perth Phone: 9321 4789
Upon arrival at the Barrack Street Jetty, depart the ferry and continue walking up along Barrack Street. Take your first left onto The Esplanade and carry on through the William Street intersection onto Mounts Bay Road. The PCEC is located on your left past the Esplanade Busport.
EARTH and ENVIRONMENT in the School of Earth & Geographical Sciences at U W A ENVIRONMENT
GEOGRAPHY
GEOLOGY
PLANNING
I M ;
THE UNIVERSITY WESTERN
Achieving International Excellence
SOILS
CRICOS code 00126G
Perth is a national and international centre for minerals and energy exploration.The School of Earth & Geographical Sciences occupies modern and historic buildings on the campus of The University of Western Australia, situated on the Swan River foreshore with views of Perth city. The School's activities span the Earth sciences (including geology, geochronology, geophysics and geochemistry, minerals and resources, petroleum studies, palaeontology and biostratigraphy, sedimentology, structural analysis and tectonics, geochronology, geophysics and geochemistry) as well as physical and human geography, soil and water management, climate studies, geothermal energy, land rehabilitation and urban and regional planning and development. A t undergraduate level, the School is responsible for teaching a comprehensive program of majors and contributes t o Degrees and Programs alone and with other disciplines. BSc and BA Honours and 4th-year degree research training are delivered across the entire program. A t postgraduate level the School delivers coursework as Graduate Certificates, Postgraduate Diplomas and Masters, and contributes t o other Faculty postgraduate programs. Diplomas, Masters and PhD by research are standard. The School has a very strong research environment with research centres of excellence and specializations, new initiatives, and collaborations of national and international significance. Centres include: The Centre for Exploration Targeting,The Centre for Land Rehabilitation,The Institute for Regional Development ,The Western Australian Geothermal Centre of Excellence, and (currently being established) The Centre for Petroleum Geoscience.
FOR FURTHER INFORMATION:
OF
AUSTRALIA
see our website w w w . s e g s . u w a . e d u . a u or telephone 0 8 6 4 8 8 2 6 6 6 ; fax 6 4 8 8 1 0 3 7 ; email j k i n g @ s e g s . u w a . e d u . a u
^
Burswqod Station
'Claisebrook j§ Station J
fRussett o: 'Square ^
s H <5
Rj D © E
Wellington Square 21
Town
Station
jWACA)
The Esplanade Langley Park
Busport Perth Convention Exhibition Centre
HEIRISSON ISLAND
Catch anv Transperth bus along this major route to hotels 1 2 - 1 9 for free
BARRACK SQUARE j j ^ Barrack Stteet Jetty
All Transperth buses jvithm Free Transit Zone are free if passengers embark and disembark within marked area
Convention Venue
Places of Interest Old Swan Brewery
Perth Exhibition Convention Centre
Fraser's Restaurant Ferry to Rottnesl Island na Fremantle
Hotels
His Majesty's Theatre The Atrium Conference Centre Ambassador Hotel
Medina Grand Perth
Best Western Emerald Hotel
Pacific International Suites
Goodearth Hotel
Parmelia Hilton Perth
Art Gallery of WA The Bell Tower Perth Town Hall Government House Perth Concert Hall The Perth Mint
University of Western Australia, Currie Hall: Crawley is south west from Perth's CBD;a 5-minute taxi ride or an 8-minute bus ride.The no. 78 bus leaves from stand El, Perth Bus Port, beside the Perth Convention Centre and will take passengers to Currie Hall for a maximum fare of $2.20.
Western Australian Cricket Association Gloucester Park
NETWORKING PROGRAM & BUSINESS MEETINGS
Entry to all social functions will be restricted to those who have registered their attendance. Should you wish to attend any social functions and you have not yet registered, please see the Convention Secretariat in Meeting Room 12, Level 2 of the PCEC. Those who have registered to attend any social functions, but can no longer attend, please hand your ticket back in to the registration desk and advise the convention organisers.
STUDENT CAREERS NIGHT Date: Time: Venue: Dress code:
Tuesday 22 July 18.30-20.30 Recruitment Comer, Exhibition Pavilion Smart Casual / School Uniform
Entry to this function is by invitation only. If you are interested in further information please see the Convention Secretariat.
ICE BREAKER
GEOTRIVIA NIGHT
Date: Time: Venue: Dress Code:
Date: Time: Venue: Dress code:
Sunday 20 July 17.30-19.00 Pavilions 1 & 2 (exhibition area), PCEC Smart Casual
You are invited to attend the Ice Breaker. This is an opportunity for us to welcome you to the convention, and for you to meet fellow delegates whilst enjoying drinks and canapes. One ticket included in all convention registrations. Additional tickets cost: AUD $60.00 (incl. GST)
Come and support the Australian Earth Sciences Convention's first Geotrivia Night! Tickets must be purchased in addition to your registration. Tickets cost: AUD $35.00 (incl. GST) Price includes light snacks. A full cash bar will also be available.
CONVENTION DINNER
HAPPY HOURS Date: Time: Venue: Dress code:
Tuesday 22 July 19.00-22.00 Meeting Room 5, Level 2, PCEC Smart Casual
Date: Time: Venue: Dress code: Seating:
Monday 21 July & Tuesday 22 July 17.45-18.45 Pavilions 1 & 2 (exhibition area), PCEC Smart Casual
You are invited to attend the Happy Hours. This is a further opportunity for you to network with delegates whilst enjoying drinks. One ticket for each Happy Hour included in all convention registrations.
Wednesday 23 July 19.15 for a 19.30 start / 19.30 - 23.00 for dinner Level 3, PCEC Evening Attire Free seating
Join us for this highlight event on the social program. Delegates and partners are invited to attend the dinner. Enjoy an evening of fine food, wine and entertainment at one of Australia's premier venues. Places are limited, so if you haven't already registered and paid for your attendance but wish to attend, please see the Convention Secretariat. Tickets must be purchased in addition to your registration. Tickets cost: AUD $110.00 (incl. GST)
BUSINESS MEETINGS SUNDAY 20 JULY Room: Boardroom 4 Executive Boardroom
Level: 1 1
Time: 1000- 1700 1430- 1730
Meeting: Geological Society of Australia Council Meeting Heads of Departments: Excellence in Research for Australia Meeting
MONDAY 21 JULY Executive Boardroom Boardroom 4 Boardroom 4
1 1 1
1040- 1140 1700- 1800 1830- 2000
Specialist Group in Education Annual General Meeting Earth Sciences History Group Annual General Meeting Geological Society of Australia Annual General Meeting
TUESDAY 22 JULY Executive Boardroom Meeting Room 10 Boardroom 3 Executive Boardroom Boardroom 4 Meeting Room 1
1 2 1 1 1 2
1245 - 1345 1715 - 1845 1745 - 1845 1800- 2000 1800- 2000 1830- 1930
Australian Journal of Earth Sciences Editorial Meeting Australasian Sedimentologists Group "Private Function'' Australian Geoscience Council Annual General Meeting Australian Stratigraphy Commission Annual General Meeting Specialist Group in Economic Geology Meeting Specialist Group Solid Earth Geophysics Annual General Meeting
WEDNESDAY 23 JULY Boardroom 4 Boardroom 3
1 1
1245 - 1345 1300- 1400
Specialist Group in Planetary Geology Meeting Specialist Group in Volcanology Annual General Meeting
SPONSORS 11 diamond & platinum
DIAMOND SPONSOR & GEOTRIVIA NIGHT SPONSOR Rio Tinto
sO? ^
O WWW. riotinto. com
Shannon Garcia Communications and External Relations 152-158 St Georges Tee Perth WA 6000, Australia T: +61 8 9327 2000 E: extemalrelationswa@riotinto.com
Rio Tinto finds, mines and processes the earth's mineral resources - metals and minerals essential for making thousands of everyday products that meet society's needs and contribute to improved living standards. To deliver superior returns to shareholders over time, Rio Tinto takes a long term and responsible approach to the Group's business. This means concentrating on the development of first class orebodies into large, long life and efficient operations, capable of sustaining competitive advantage through business cycles. The Group's major products include aluminium, copper, diamonds, energy products, gold, industrial minerals (borates, titanium dioxide, sah and talc), and iron ore. Its activities span the world but are strongly represented in Australia and North America. There are also significant businesses in South America, Asia, Europe and southern Africa. Wherever Rio Tinto operates, health and safety is the first priority. Group businesses also put sustainable development at the heart of their operations. They work as closely as possible with host countries and communities, respecting their laws and customs. For Rio Tinto it is important that the environmental effects of its activities are kept to a minimum and that local communities benefit as much as possible from operations. Mineral exploration is a high risk activity in economic terms, in that only one in 350 mineral prospects that are tested result in a mine. We believe in having a critical mass of projects happening at any one time, and they are selected through a rigorous process of prioritisation. Our Exploration Group employs 250 geoscientists around the world and has a total staff of approximately 950 people. It is organised into regional muhi-commodity teams. This gives the group local presence, an in depth understanding of the operating environment and a holistic view of geological terrains. At the same time, programmes are prioritised on a global basis so that only the best opportunities are pursued. There are currently five of these regional teams. In addition, another small team that deals with project generation covers the world looking for new opportunities. At the end of 2007, we were exploring in 30 countries and assessing opportunities in a further 20 for a broad range of commodities including bauxite, copper, coking coal, iron ore, industrial minerals, diamonds, nickel and uranium. In 2007, we spent US$576 million on exploration, an increase of US$231 million over 2006. To find out more about our operations, exploration programme and job opportunities, visit www.riotinto.com
PLATINUM SPONSORS Norilsk Nickel Australia
Kate Luke, Team Assistant - Geology Level 3, 88 Collins Street West Perth, WA 6005, Australia N O R I L S K N I C K E L T; +61 8 9426 0102 /F: +61 8 9481 4077 E: kate.luke@nomik.com.au www. nornik. ru/en/our_products/norilsknickelaustralia/ It is almost 12 months since the formation of Norilsk Nickel International and its subsidiary, Norilsk Nickel Australia, through the acquisition of OMG Nickel and LionOre Mining. In this time, Norilsk has cemented its position in the top three nickel producers in Australia and as the largest Australian exporter of intermediate nickel products. ll^
Norilsk Nickel Australia is part of the Norilsk Nickel Group, the world's largest nickel and palladium producer and one of the largest producers of platinum and copper. Norilsk Nickel originated in Russia over 70 years ago and now has operations in Russia, Finland, Botswana, South Africa, the USA and Australia. Norilsk has four Australian operations: Black Swan, Lake Johnston, Waterloo and the Cawse laterite operation with a combined 2008 production target of approximately 40,000 tonnes of contained nickel. These are located in the prime nickel producing NorsemanWiluna Greenstone Beh in south-central Western Australia. The company's exploration and projects groups, along with research & development and corporate services fianctions are located in Perth. Norilsk's Australian nickel exploration budget is one of the most significant programmes in Australia with some $55 million in expenditure planned for 2008. Norilsk Nickel Australia is committed to sustainable growth through unwavering focus on health and safety, environment and community.
Gold Fields FIELDS
Sharon Andrews, Mineral Resource Administrator PO Box 359 Kambalda, WA 6442, Australia T: +61 8 9088 1168/F:+61 8 9088 1112 E: sharon.andrews@goldfields.com.au
www.goldfields. co.za Based in South Africa, internationally Gold Fields owns: • St Ives and Agnew Gold Mines in Western Australia • Driefontein, Kloof & Beatrix Gold Mines in South Africa • Tarkwa & Damang Mines in Ghana • Choco 10 in Venezuela The group's exploration activities for gold and platinum extend from Africa and Australasia to Europe and South America. Employing over 44,000 people worldwide. Gold Fields is one of the largest unhedged gold producers. Gold Fields is committed to responsible mining of natural resources and acts responsibly in all areas of environmental management.
Australian Earth Sciences Convention 2008
12 SPONSORS platinum ^ gold
PLATINUM SPONSOR - continued St Ives Gold Mine St Ives is located 80km south of Kalgoorlie-Boulder in Western Australia. St Ives employs over 700 staff and contractors in various professions including engineering, geology, processing, administration, finance, human resources, maintenance, heavy vehicle operation, drilling & haulage. St Ives consists of three underground mines and various open pit mines. Spending more than $20M annually to find new and exciting ore bodies, St Ives currently produces over 450,000 ounces of gold per annum. Agnew Gold Mine Agnew is located 375km north of Kalgoorlie-Boulder and employs approximately 350 staff and contractors in various profession including administration, finance, human resources, heavy vehicle & machine operation, geology, maintenance and engineering. Agnew consists of an underground mine where material from the mine is processed at the site's mill. Agnew has an active and robust exploration program, dedicated to exploring the area to ensure the future of the mining operation. Agnew produces over 200,000 ounces of gold annually.
GOLD SPONSORS CSIRO Exploration & Mining Dr David Gray Acting Theme Leader - Discovering Australia's Mineral Deposits PO Box 1130 Bentley, WA 6151, Australia T: +61 8 6436 8678 F: +61 8 6436 8555 E: david.gray@csiro.au www.csiro.au CSIRO, working through the Minerals Down Under National Research Flagship, is developing revolutionary new technologies and ideas that will transform the minerals industry in Australia. The resource sector contributes almost ten per cent of Australia's Gross National Product and is the basis of much of Australia's prosperity. However, a combination of falling exploration success and increased environmental scrutiny means that the future of the sector is uncertain and dependent on finding innovative and environmentally friendly ways to explore for, mine and process minerals.
CSIRO's groundbreaking R&D will reinvigorate mineral exploration in Australia. An improved understanding of mineral systems and the use of new technologies are enabling explorers to predict mineral targets with greater accuracy. Mining R&D is helping to reduce the environmental footprint of mining and improve mine safety, productivity and sustainability. In mineral processing, CSIRO is pursuing new techniques that will allow previously unrecoverable resources to be processed.
Australian Earth Sciences Convention 2008
Curtin University of Technology WA School of Mines Administration I • Z0B Locked Bag 22 V - . U r t l n h i Kalgoorlie WA 6433, Australia University of Technology
j.
g 9Qgg 5 ^ 7 9 / p. + 5 1 g 9 0 8 8 6 1 7 9
E: WASMadmin@curtin.edu.au www. wasm. curtin. edu. au Curtin University of Technology is Western Australia's largest university, and its geoscience activities are located in the Western Australian School of Mines, a major provider of education and research to the mining, petroleum and groundwater sectors in Australia and overseas. WASM graduates over 200 students each year, including 50 bachelors graduates in geology and geophysics, and also offers postgraduate courses in topics such as geomechanics, GIS, hydrogeology, mineral and petroleum exploration, and mineral economics, that allow geoscience professionals to upgrade technical skills. The School undertakes high-impact fundamental and applied research across several disciplines. Geoscience has a particularly high profile, with over 40 academics and 50 research students, supported by world-class facilities and substantial funding from government and industry sources. This has resulted in Curtin being ranked top Australian institution for geoscience research impact by Thomson Scientific in 2007, based on the number of citations per research article in 2002-2006.
Integra Mining Alice Hirlbatt, Executive Assistant 168 Stirling Highway Nedlands, WA 6009, Australia T: +61 8 9423 5920 / F: +61 8 9423 5930 E: info@integramining.com.au www. integramining. com. au
ifitegra
Integra Mining is an aggressive Australian gold explorer with a proven discovery track record, a substantial gold resource base and a strong platform for building a significant new Australian gold production house. The Company's flagship Aldiss-Randalls Gold Project is located 50-100km east of Kalgoorlie and currently has a consolidated Inferred gold resource of 20 million tonnes grading 2.8g/t Au for 1.75 million contained ounces. The existing resources base is subject to a production pre-feasibility study underpinned by Integra's recent Salt Creek 'blind' grassroots gold discovery. Notably, Integra Mining had no reportable resources prior to August 2004. Integra's Managing Director, Mr Chris Cairns, has significant experience in the discovery and development of gold deposits with Integra and in previous positions with Sino Gold Limited and LionOre Mining International. Mr Cairns will be discussing exploration strategy, with particular reference to gold exploration in the context of global mining and exploration trends.
SPONSORS silver & other sponsors
SILVER SPONSOR
AFTERNOON TEA SPONSORS
University of Western Australia
Anglogold Ashanti Australia Limited
T H E UNtvrRSfTY OF WEST£RN AUS i t U l lA
Prof. Peter Cawood School of Earth & Geographical Sciences 35 Stirling Highway Crawley, WA 6009, Australia T: +61 8 6488 3422 / F: +61 8 6488 1037 E: p.cawood@uwa.edu.au
www. segs. uwa. edu. au The School of Earth and Geographical Sciences at UWA spans the Earth sciences as well as physical and human geography, soil and water management, geothermal and climate studies and urban and regional planning and development. A comprehensive undergraduate program of majors and specialised Degrees and Programs is offered, as well as Honours and 4th-year degree research training. At postgraduate level there are Graduate Certificates, Postgraduate Diplomas and Masters by coursework, and Diplomas, Masters and PhD by research. The School has a strong research environment with research centres (in Exploration Targeting, Land Rehabilitation, Regional Development, Geothermal Energy and Petroleum Geoscience) and specializations, new initiatives, and collaborations of national and international significance.
Duncan Gibbs Exploration Manager Australia PO Box Z5046 ANGLOGOLD Perth, WA 6831, Australia ASWANTI AUSTRALIA T: +61 8 9425 4633 / F: +618 9425 4663 E: dgibbs@anglogoldashanti.com www. anglogoldashanti. com
iL,
Australian Journal of Earth Sciences Taylor & Francis Customer Service Co-ordinator Level 2, 11 Queens Road Melbourne, VIC 3004, Australia T: +61 3 9866 2811 / F: +61 3 9866 8822 E: enquiries@tandf.com.au www. informaworld. com
STUDENT SPONSOR Department of Industry & Resources Geological Survey of Western Australia Dr Tim Griffin, Executive Director 100 Plain Street I Geological Survey of East Perth, WA 6004, Australia ! Western Australia ' ' Industry and Resources
STUDENT CAREERS NIGHT MAJOR SPONSOR Independence Group NL INDEPENDENCE GROUP Ni
^ ^
Tim Kennedy, Exploration Manager Lcvcl 3, PDM Housc, 72 Mclvillc Parade p^j^j^^ WA 6151, Australia T: +61 8 9367 2755 / F: +61 8 9367 3288 E: tkennedy@igo.com.au
T: +61 8 9222 3168 / F : +618 9222 3633 E: geological.survey@doir.wa.gov.au www. do ir. wa. gov. au/gswa
BEST PAPER PRIZE SPONSOR Geoscience Australia
www.igo.com.au Australian Government
KEYNOTE SPEAKER SPONSOR Geoconferences (WA) Inc Jocelyn Thomson, Secretariat PO Box 4052 Victoria Park, WA 6979, Australia T:+61 8 9355 2 1 6 4 / F : + 6 1 8 9355 2164 E: secretary@geoconferences.org www.geoconferences. org
G
EOCONFERENCES
Geoscience Australia
Peter Southgate GPO Box 378 Canberra, ACT 2601, Australia T: +61 2 6249 9206 E: peter.southgate@ga.gov.au
www.ga.gov.au
OFFICIAL PUBLICATION SPONSOR
(WA) INC.
MORNING TEA SPONSOR
Resource Information Unit ^ mm • M I • •
• • • • ^MP
Gnomic Exploration Services Pty Ltd
A
GraoMfc
jfotion S«roio»» fHy Uf»
Chrissy Maguire, Managing Director PO Box 651 Townsville, QLD 4810, Australia T: +61 7 4721 2 7 3 7 / F : + 6 1 7 4721 2231 E: gnomic@gnomic.com.au
Rob Tyson, General Manager / Nina Dimitrova, Marketing Manager Hay Street Subiaco, WA 6008, Australia T:+61 8 9382 3955 / F : + 6 1 8 9388 1025 E: rtyson@riu.com.au, adimitro va@riu. com. au
www.riu.com.au
www.gnomic.com.au
Australian Earth Sciences Convention 2008
13
14 PLENARY KEYNOTE SPEAKERS
Prof. Peter Cawood - University of Western Australia Mawson Lecture: Making Mountains: Geological Drivers and Environmental Consequences
Mountains are one of the key manifestations that we live on a dynamic planet. They are driven by the movement of surface plates that are in turn a response to the Earth's heat engine.
n
Classic models of mountain building involve the collision of buoyant surface plates (e.g. Himalayas). Such models however, fail to explain those mountains that form in an environment of ongoing subduction of oceanic plates beneath continental plates (e.g. American cordilleras). The Terra Australis mountains were a major cordilleran-type mountain beh that extended some 18,000 km along the proto-Pacific margin of the Gondwanan supercontinent from eastern Australia to South America. Phases of mountain building along the beh are synchronous with, and driven by, phases of global supercontinent assembly. Termination of subduction zones within the interior of the supercontinent, during phases of assembly, is compensated for by increased plate coupling along the exterior of the supercontinent. Mountains impact on atmosphere/water interactions with consequences for climate and the distribution and evolution of life. A major pulse of contraction along the Terra Australis mountains, some 300 million years ago, marks a major change in global climate, corresponding with the Gondwanan deglaciation. Prior to this time, Gondwana was glaciated by the longest ice age recorded in Earth history (90 to 200 million years), which caused 100-250 m changes in global-sea level. Termination of the glaciation and change to a relative protracted phase of warm global temperatures, corresponds with the development of the Terra Australis mountains, probably through capture of orographic precipitation leading to desertification and deglaciation within the intemides of Gondwana. Peter Cawood s research is concerned with the integration offield-based studies of mountain belts and their bounding cratons with the development and application of tectonic models. He is an international leader in understanding the development of the continental lithosphere through time. His work involves globalpalaeogeography and continental reconstructions throughout geological time using his specialist knowledge of structural geology and tectonic processes. He has worked on collisional and accretionary orogens ranging in age from Archaean to Recent from disparate geographic areas around the globe, at scales ranging from macroscopic to microscopic, and in applying microanalytical techniques (electron and ion microprobe) to provenance studies.
Dr. Peter McCabe - CSIRO Australia's Energy Future (lYPE Theme: Resources - Towards Sustainable Use) Although Australia is a large country, it is not endowed with a proportionally large amount of fossil fuel resources. Despite this, the small population allows Australia to be the world's largest exporter of coal and an exporter of gas. Fossil fuels have supplied between 91 and 93% of the world's energy supply for the last 60 years. Long-term prediction of production is difficuh but, given the abundance of fossil fuels, they are likely to remain the dominant part of the world's energy mix for decades to come. An understanding of the global geographic distribution of fossil fuel is critical to consideration of future energy scenarios for Australia and has profound geopolitical implications, especially if there is instability within a major producing country or disruption in supply routes. There are a number of Australian basins that remain to be explored for petroleum. The critical question is not whether these basins have a petroleum system but whether the largest field will permit economically viable development. Although fossil fiiels will likely dominate Australia's energy supply for decades, a transition to other energy supplies is inevitable in the long-term. Most of the world's renewable energy currently comes from hydroelectricity and biomass, which are not resources that Australia has in abundance. However, Australia's geographic and geologic settings are particularly favorable for many other types of renewable energy generation: notably solar, wind, wave, tidal, and geothermal power. With 23% of the world's uranium reserves and remote locations for waste disposal, Australia is also better positioned than most countries to have a nuclear power industry if it so wishes. Concerns about climate change may drive the search for alternate energy sources but C02 emissions can be substantially reduced by greater efficiencies in fossil fuel use. Geosequestration also offers an answer to lowering greenhouse gas emissions. Dr Peter McCabe has spent over 30 years in industry, academia, and government pursuing research related to fossil fuels. He is internationally recognized as an expert in petroleum geology, sedimentology, and stratigraphy He joined CSIRO in 2007 where he is Theme Leader for the Petroleum Resources Division. Before joining CSIRO he worked for several organizations including the U.S. Geological Survey, Exxon Production Research Co., the Alberta Research Council and the University of Nebraska. Dr McCabe is currently President of the American Geological Institute (AGI). He is also the AAPG Distinguished Lecturer for the Asia Pacific region for 2007- 08. Dr McCabe is a Past-President of the Society for Sedimentary Geology (SEPM). He has given many talks on oil and natural gas resources and in 2006 was a guest speaker at a World Economic Forum meeting.
Australian Earth Sciences Convention 2008
PLENARY KEYNOTE SPEAKERS 15
Prof. Malcolm Walter - University of New South Wales The Geological History of Climate Change If it were not for greenhouse warming Earth would have been frigid desert, or ice-covered, for at least the first two billion years of its history. The course of biological evolution would have been totally different, or at least delayed by a billion years or more. We certainly would not have been here to talk about it. This is not an apologia for those who consider that current climate change is not anthropogenic. It is a cogent hypothesis. Similarly, that Earth is currently warming is beyond dispute, but the cause is another matter. That the cause is dominantly anthropogenic is a cogent hypothesis. As we all know, in the past there have been profound changes in climate, leading, for example, to the great ice ages of the Neoproterozoic. There is very strong evidence of changes in the composition of the atmosphere throughout geological history. Those changes are hypothesised to have been one of the drivers of climate change. The evidence is circumstantial, but strong. Substantial other drivers include the long-term evolution of the Sun, short-term variations in the energy output of the Sun, the evolution of the biosphere, long-term trends in oceanic composition, and major tectonic events. There are strong feedback loops between many of these processes. Over recent decades those processes have been elucidated through the detection of signals in the rock record, for example, stratigraphically well-controlled sets of carbon isotopic analyses of sedimentary carbonates and kerogen. Such datasets reveal local and global changes in the carbon cycle, including the relative size of the carbon reservoir in the atmosphere. While the rock record will not reveal the causes of current climate change it offers insights into timing and processes that elucidate and place constraints on interpretation of the situation. Geology offers the big picture and will be part of any solution. Malcolm Walter is a Professorial Fellow at Macquarie University in Sydney, Director of the Australian Centre for Astrobiology based at that university, and Director ofM. R. Walter Pty Ltd. He has worked for 35 years on the geological evidence of early life on Earth, including the earliest convincing evidence of life. Since 1989 he has been funded by NASA in their ''exobiology " and "astrobiology'' programs, focusing on microbial life in high temperature ecosystems, and the search for life on Mars. He is a member of the Executive Council of NASA s Astrobiology Institute. During 1999 his book ''The Search for Life on Mars " was published by Allen & Unwin. He has published more than 100 articles and several other books. He also works as an oil exploration consultant and a consultant to museums, and was curator of a special Centenary of Federation exhibition on space exploration (for the National Museum ofAustralia in Canberra, Museum Victoria, and elsewhere). In 2004 Malcolm was elected a Fellow of the Australian Academy of Science.
Mr. Philip Commander - Department of Water (WA) The Yarragadee Aquifer (lYPE Theme: Groundwater - Towards Sustainable Use) The Yarragadee Formation is a 3000m thick succession of sands and minor shale of mid to late Jurassic age underlying the Cretaceous Leederville Formation aquifer. It is a major aquifer in the Perth Basin, generally containing fresh groundwater and generally marks the base of the meteoric groundwater flow system. The groundwater resources of the aquifer support water supply to Geraldton, Bunbury and Busselton, and about one third of Perth's groundwater supply, as well as irrigation and mining. The formation is divided into a northern and a southern flow system, and is absent by erosion over the Harvey Ridge south of Perth. The South West Yarragadee below the Blackwood Plateau has been systematically investigated since the 1980s and has long been part of long term planning for Perth's water supply. The formation contains a 600m thick unit of mainly coarse sand which comprises the main aquifer horizon. Following two exceptionally dry years, a major investigation was undertaken in 2003 to assess the prospects of supplying 45GL/a to Perth from a borefield in the Yarragadee aquifer on the Blackwood Plateau. The investigation, comprising some 68 new boresites, defined the area of direct recharge south of the Blackwood River, and showed that the potentiometric head, groundwater salinity and groundwater carbon-14 age distribution are in agreement with an origin from direct ramfall recharge on the outcrop. However, a major problem in understanding the aquifer flow system is quantifying the leakage from the overlying Leederville aquifer, which covers a greater area. Although there is a very large storage of low salinity groundwater, abstraction is limited by the need to limit impacts of drawdown where the aquifer is close to the surface, especially along the Blackwood River and adjacent wetlands which are supported by discharge from the aquifer. The proposal was not proceeded with, mainly due to uncertainty of the magnitude of drawdown in the critical Blackwood River area, and the inherent uncertainties in proposed adaptive management. Philip Commander has spent 37years working on the hydrogeology of Western Australia with the Geological Survey and the Department of Water where he is currently Principal Hydrogeologist. Philip has been concerned mainly with groundwater resources, carrying out investigations throughout the state and publishing on a variety of topics concerning the hydrogeology of the state, and has also been involved in national projects and groundwater resource reviews. He has worked on the south west Yarragadee off and on since 1975, and was closely involved with the recent investigation into supplying the integrated water supply scheme. Australian Earth Sciences Convention 2008
16 PLENARY KEYNOTE SPEAKERS
Dr. Barry Drummond - Geoscience Australia
Tsunami Hazard in Australia and Steps Being Taken to Mitigate it (lYPE Theme: Hazards - Minimizing Risk, Maximising Awareness) Most tsunami are caused by earthquakes that displace the water column by faulting the sea bottom or causing submarine landslides. Australia is surrounded by 8,000 km of active, earthquake-prone, plate margins. In Western Australia tsunami hazard is highest in the northwest facing the subduction zones of the Indonesian arc. Tsunami hazard along the eastern coast comes from subduction zones from the Solomon Islands in the northeast to the Puysegur Trench south of New Zealand. Images of the tsunami of 26 December 2004 impacting Thailand showed tsunami several metres high inundating large sections of shore line. Australia is much farther from the tsunami sources, and is more likely to face tsunami with smaller heights regionally but possibly increasing unpredictably to much larger heights locally. The Australian Government has funded the establishment of the Australian Tsunami Warning System (ATWS). End-to-end warning systems consider the development of mitigation strategies, monitoring for events, issuing warnings, and response and recovery phases after the event. The geosciences play important roles in several of these steps. Hazard mapping requires the study of the earthquake source regions (fault geometry, maximum likely earthquake magnitude and its probability, and estimates of the resulting tsunami height and direction). The development of mitigation strategies requires estimating the propagation of tsunami across the deep ocean, shoaling in the shallow waters near the shore line, the inundation of the land and the impact on people and infrastructure. The detection of earthquakes requires access to national and international seismograph networks that work interoperably in near-real-time, and algorithms for the rapid automatic determination of their locations (including depth), magnitudes and focal mechanisms. In cases where there are no sea level gauges between the source and coastline, the warning systems rely entirely on earthquake parameters. Published with the permission of the CEO of Geoscience Australia. Co-Author: Trevor Dhu, Geoscience Australia, Canberra ACT Barry Drummond was appointed head of the Earth Monitoring Group ofprojects in Geoscience Australia following a decision by the Australian Government to establish an Australian Tsunami Warning System (ATWS) after the devastating Indian Ocean tsunami of 24 December 2004. The ATWS is being established jointly by Geoscience Australia, the Bureau of Meteorology and Emergency Management Australia. Other projects in the Earth Monitoring Group monitor the Earth s magnetic field, screen for nuclear explosions, and contribute to capacity building for volcano monitoring in Papua New Guinea and Indonesia. The national geodesy program is also part of the group. Before moving to the Earth Monitoring Group, Barry led a number ofprograms that used seismic reflection and refraction techniques and potential field data to image many aspects ofAustralian geology. He was foundation Director of the AN SIR Major National Research Facility. He is a member of the GSA, ASEG, SEG and PESA, and a member of the editorial board of the Australian Journal of Earth Sciences.
Prof. Michael Gurnis - California Institute of Technology, USA Historical Geodynamics: From Crust to Core Mantle Boundary (TYPE Theme: Deep Earth - From Crust to Core) A quantitative convergence is emerging on the linkages between the dynamics of the Earth's deep interior and the evolution of continents. This convergence is being driven broadly from advances in geodynamics, seismology, mineral physics, and synthesis of the vast geological history of continents. Global seismic images of the whole mantle have revealed that subducted oceanic lithosphere can be found down to the core mantle boundary. Images of subducted slabs reveal the history of subduction, indicting when subduction has stopped and started along different plate boundaries. Subduction of the oceanic lithosphere may primarily be responsible for the redistribution of hot thermo-chemical regions within the deepest regions of the earth. Such hot regions in turn may control the occurrence of hot-spot volcanism. Laboratory experiments of mineral deformation point to the important role volatiles, especially water, play in influencing the deformation of the mantle and suggest that water weakening may play a central role in determining the nature of earth dynamics, especially the dynamics of subduction. The Australian region over the Mesozoic and Cenozoic has played a central as a natural laboratory for constraining geodynamic processes and has been used as the 'type locality' in the merging of plate reconstructions, seismic tomography, and the surface evolution of the continents (especially regional sea level and stratigraphy) using advanced geodynamic models. Michael Gurnis is the John E and Hazel S Smits Professor of Geophysics at the California Institute of Technology. A graduate of the Australian National University, Gurnis has long-standing interests linking the geological evolution of the ocean floor and continents with the dynamics of the earth s interior Recently with his graduate students, Gurnis has been involved with a wide range of studies, including those involving long-term sea level change, the tectonics of active plate margins, and the structure & dynamics of the lower most mantle. In addition, he is currently Director of the NSF Center, Computational Infrastructure for Geodynamics, a new community partnership between computational sciences and earth sciences in the US. Australian Earth Sciences Convention 2008
PLENARY KEYNOTE SPEAKERS
17
Dr. Jeffrey Taylor - Hawaii Institute of Geophysics and Planetology, U S A New Views of the Chemistry and Geology of the Crust of Mars Data from spacecraft orbiting Mars, rovers on its surface, and meteorites give us a new look into the planet's bulk composition, early differentiation, and crustal evolution. Mars contains more FeO and has higher K/Th than does the terrestrial mantle, indicating that there were compositional gradients in the solar nebula. Meteorite isotopic data demonstrate that the planet differentiated early, perhaps only 10-15 My after formation of CAIs (the oldest objects in the solar system). Primary differentiation likely involved a magma ocean, which produced at least half the mass of the 50-km-thick basaltic crust we observe. Much of the subsequent geological activity took place during the next approximately 800 My. Magmatism added up to 25% of the final crust. Heavy bombardment mixed the crustal column as it was being made, producing a substantial amount of fine-grain sediment, forming layered sequences. Impacts (including of icy objects) and magmatism added volatiles to the atmosphere, causing intermittent periods of rainfall, producing valley networks, sedimentary deposits, and weathering and hydrothermal products. Because of the lack of plate tectonics the ancient surface materials compose some of the surface even today, providing some of the raw materials for the ubiquitous dust. The relatively wet conditions do not appear to have pervasively weathered the surface, suggesting that the events were of relatively short duration and at low T. Phyllosilicates were produced during this time, but only small amounts of carbonates. A hypothetical early ocean in the northern lowlands is not consistent with low chlorine in those areas, in spite of impressive outflow channels clearly having disgorged huge amounts of water. Such events must have been short, intense outbursts. Since about 3.5 Gy ago the rates of magmatism, impact, and aqueous alteration declined greatly. Alteration of rocks at the landing sites involved acidic solutions and low water/rock ratios. Orbital chemical measurements indicate that this is a global phenomenon on this planet now shaped mostly by aeolian processes and glaciation. G. Jeffrey Taylor received his undergraduate degree in physics from Colgate University and his Ph.D. in geology and geophysics from Rice University. He is currently a research professor in the Hawaii Institute of Geophysics and Planetology at the University of Hawaii. Dr Taylor has done extensive work on the mineralogical and chemical make up of lunar samples and meteorites, publishing over 160 refereed articles. His main scientific interest is in understanding the processes involved in planetary evolution, with emphasis on magmatism and impact on the Moon, Mars, Mercury, and asteroids, and aqueous alteration processes on Mars. He is a member of the Mars Odyssey Gamma-Ray Spectrometer Team. Jeff Taylor also has extensive experience in education and public outreach. He and Linda Martel (Hawai 7 Institute of Geophysics and Planetology) publish an online science magazine. Planetary Science Research Discoveries (www.psrd.hawaii.edu).
Geology and Geophysics @Curtin geology.curtln.edu.au geophysics.curtin.edu.au
WA Scliool of IVIines wasm.curtin.edu.au
Curtin University of Technology and the WA School of Mines welcome delegates to the Australian Earth Science Convention Western Australian School of Mines Faculty of Science and Engineering Curtin Univeristy of Technology Australia s largest piovider of university geoscience training with a comprehensive range of undergraduate and postgraduate courses in geuiugy geophysics and related disciplines {An tr-ili in tie-rtti ih t C i i m if Oil b t o " weoce Teitfify tducation Profiie)
Ranked Austiaiia s highest impad research institution m geoscience in 2007, Hwmstii ScuMiifit
« u ig
t itioiis pfcT paper in zOoii 2006)
Promoting excellence in geoscience education and research since 1902
I
CurtinW
University of Technology
CRICOS Provider Code 00301J
Australian Earth Sciences Convention 2008
18
CONVENTION PROGRAM m o n d a y 21 july
0900-0940 Prof. Lvn Beazlev, University of Western Australia 0940-1030
' •
.
•
•
PLEf^AftYSESSION I^MAWSONLECTIIEE-Chair:ioaHroasfcf
/
V...,.-
Prof. Peter Cawood, Universitv of Western Australia M O R N I N G TEA & POSTER PRESENTATIONS
1030-1100 1100-1245
A l : MecUilii Koom 5
A2: Meeting Room 2
RESOURCES (1) - Exploration Strategies and Technologies Chair: Dr RaviAnand
EVOLUTION O F LIFE & SOLAR S Y S T E M (1) - Evidence for Early Life Chair: Dr Kathleen Grey
A4i|i«e^Roofn6
Meeting Room 3
RESOURCES (2) - Being Smarter with GEOSCIENCE IN T H E SERVICE OF SOCIETY (1) - Groundwater our Data Chair: Mr Phil Commander Chair: Mr Gerry Fahey
1105-1125 KEYNOTE: How CRC LEME has provided breakthroughs in exploration through cover-] 4 years of innovative regolith geoscience R & D Dr. Steve Rogers, CRC Leme
KEYNOTE: The Art and Science of Data KEYNOTE: The Quest for Perfection KEYNOTE: The Role of Hydrogeology Analysis - Building Talent for Future - Biogenicity and the Early Fossil Record in Mining Resource Management Prof. Stanley Awramik, Uni. of Doug Brown, MWH Jacqui Coombes, Coombes Capability California, USA
Stimulating greenfields mineral exploration:the west Yilgam laterite geochemistry database Dr. Paul Morris, Geological Survey ofWA
The Palaeontology and Palaeoecology of the 2.7Ga Tumbiana Formation, Pilbara Craton, Western Australia. Jessica Coffey, Macquarie Uni.
Compiling continent wide datasets for intelligent analysis David Jenkins, Terra Search Pty Ltd
Studying surface attributes to reveal hidden regolith profiles: Geochemistry and mineralogy of termite mounds of the Coyote Au-deposit and surrounds, Western Australia Anna Petts, CRCLEME/Uni. of Adelaide
Microbially induced sedimentary structures - signs of life in Archean to m o d e m sandy marine settings Dr. Nora Noffke , Old Dominion Uni., USA
Australian Junior Exploration Floats, 2001- 2006, And Their Implications For IPOs A/Prof. Pietro Guj, The Uni. of WA
Relationships between magnetite trace element compositions and mineral paragenesis Blackwell Singoyi, CODES A R C Centre of Excellence in Ore Deposits
Highly elaborate putative microfossils from >2.97 Ga chert, Pilbara Craton: indications of cell division? Dr. Kenichiro Sugitani, Nagoya Uni., Japan
What are in-situ gold resources worth? An empirical study Mr. Jonathan Bell, Curtin Uni. of Technology (WASM)
1125-1145
1145-1205
1205-1225
1225-1245
124S-1345 1345-1530
AS:M^lRooml RESOURCES (3) - Precompetitive Geoscience Information-Window into the Future Chair: Dr Rick Roserson Vlineral Exploration-related research in the Minerals Down Under National Research Flagship Paul Roberts, CSIRO Exploration and Mining Queensland - Program Initiatives to Attract Exploration Investment Mai Jones, Geological Survey of Queensland
Looking for mine water supply in the area of limited water allocation (Boggabri Coal, N S W ) Katarina David, Parsons Brinckerhoff
State Survey Initiatives: What have we learnt from PACE? Dr Paul Heithersay, P I R S A
KEYNOTE: Securing Australia's future wealth. The role of precompetitive geoscience and Geoscience Australia's program James Johnson, Geoscience Australia
LUNCH (Sponsored by Rio Tinto) & POSTER PRESENTATIONS HI: Meeting Koont 5
B2: MeettRg Room 2
RESOURCES (1) - Exploration Strategies and Technologies Chair: Mr Warren Potma
EVOLUTION OF LIFE & SOLAR SYSTEM (I) - Evidence for Early Life Chair: Prof. Malcolm Walter
i n : Meeting Koom ^ RESOURCES (2) - Being Smarter with GEOSCIENCE IN T H E SERVICE OF SOCIETY (1) - Groundwater our Data Chair: Mr Phil Commander Chair: Dr Margaretha Scott
B5: M e e t i n g Room 1 RESOURCES (3) - Precompetitive Geoscience Information - Window into the Future Chair: Dr Franco Pirajno
1350-1410
Testing deposit models in the The ~3.43Ga Strelley Pool sandstone as an Eastern Goldfields Province, WA: environment for early life the geochronology perspective using Mr Cris Stoakes, C.A. Stoakes hydrothermal monazite and xenotime KEYNOTE: The AuScope National Prof. Neal McNaughton, Curtin Uni. of Associates Consultant Geologists Virtual Core Library - Development of a Technology New National Pre-Competitive Data Set 1410-1430 Stromatolites as a record of the Jon Huntington, CSIRO Exploration Detection of K-alteration in the Cloncurry biodiversity and physiology of early Earth and Mining District, N W Queensland, using Brett Neilan, University of New South Hyperspectral Mineral Maps Wales and Massachussetts Institute of Carsten Laukamp, James Cook Uni. Technology 1430-1450
1450-1510
Next generation mineral mapping Technology advances; neutron activation borehole logging for measurement in Queensland: Another piece to the of elemental abundance, mineralogy, precompetitive geoscience data puzzle lithology, porosity and hydraulic Tom Cudahy, CSIRO Exploration and Morphological complexity and diversity in conductivity Mining Dr. Craig Smith, CSIRO the c.3.40 Ga Strelley Pool Chert, Pilbara Craton — evidence for a biogenic origin Field Portable XRF for geological in-situ Numerical Modelling of Strain Dr. Kathleen Grey, Geological Survey sampling: calibration and refinement of Localisation in the Laverton Region, ofWA instrumental precision and accuracy for Western Australia field measurements Dr. Yanhu Zhang, CSIRO Exploration Dr. Keith Sircombe, Geoscience and Mining Australia
1510-153C
Technology, Innovation and the Boom Lindsay Kirsner, Rio Tinto 1530-1600 160(^-1745
C I: Meeting Ko»m 5 RESOURCES (1) - Exploration Strategies and Technologies Chair: Dr Steve Rogers
1605-162f
KEYNOTE: Transfer of research initiatives into practice - how effectively are new concepts driving exploration 1625-164^ outcomes? Dr. Peter Williams, SRK Consulting
1645-170;
KEYNOTE: Petroleum Hydrogeology application to Groundwater Management James Underschultz, CSIRO
KEYNOTE: The impact of government pre-competitive geoscience data on mineral exploration in WA. Dr. Tim Griffin, Geological Survey WA
Hydrogeology of the Leederville aquifer near Margaret River David Schafer, Department of Water
New South Wales, New Frontiers, New Opportunities John Greenfield, Geological Survey of NSW
Ngukurr Groundwater Investigation, Northern Territory, Australia Jonothan Sumner, Northern Territory Government
Rediscover Victoria in 3D Paul McDonald, GeoScience Victoria
The TasExplore Initiative and more: Automated Polished Slab Image Analysis Hydrogeology of the Shallow Aquifers at Environments of life at 3.5-3.3 Ga; Updating the 3-D geological model of wadi el-Ghussein, NE Jordan evidence from the East Pilbara Terrane, for Olivine Crystal Size Distribution Tasmania Western Australia. Wael Al - Azaizeh, Al Al Bayt Uni., Detection Dr. Geoffrey Green, Mineral Resources Dr. Martin Van Kranendonk, Geological Jordan Dr. Eun-Jung Holden, The Uni. of W A Tasmania / Geological Survey Tasmania Siiirvpv of WA AFTERNOON TEA & POSTER PRESENTATIONS Rooml C4: Meeting Room 6 C3: M « t t i l ^ Room 3 C2: M e e t o g Room 2 RESOURCES (3) - Precompetitive RESOURCES (2) - Being Smarter G E O S C I E N C E IN THE SERVICE OF EVOLUTION OF LIFE & SOLAR Geoscience Information - Window into with our Data includies Prospectivity SOCIETY (1) - Groundv\ater SYSTEM (1) - Evidence for Early Life the Future Analysis Chair: Mr Phil Commander Chair: Dr Kathleen Grey Chair: Dr Ian Tvler Chair: Dr Suhhash Jaireth Opening up new base metals, uranium and Using numerical modelling to target A reassessment of the evidence for The Upper Loddon 'deep lead' undiscovered gold in a brown-fields REE provinces in central Australia through sulphur-based microbial metabolic activity environment, an example from Tarmoola, palaeodrainage systems are discontinuous in the early Archean at North Pole, pre-competitive geoscience due to Mid Tertiary ENE-trending faults WA. Western Australia Ian Scrimgeour, Northern Territory Warren Potma, CSIRO Minerals Down Sarah Hagerty, La Trobe University Prof. Bruce Runnegar, Uni. of Geological Survey Under National Research Flagship California, USA Discovery of a Large Palaeochannel Early Archaean Microorganisms Preferred Hyperspectral modelling in mining and Geology and Resources of New Guinea During Exploratory Groundwater exploration: advances in the understanding Elemental Sulfiir, Not Sulfate Hugh Davies, Mineral Resources Investigations at Glen Innes, N S W of structurally-controlled mineralisation Pascal Philippot, Institut De Physique Authority Graham Hawkes, Parsons Brinckerhoff Tony Roache, CSIRO Du Globe De Paris Sedimentology and Hydrogeology of Goods Road Palaeochannel, Perth, Mineral exploration in New Zealand: new Western Australia research framework and tools Sean Adamas, CRC LEME, Departmem Nick Mortimer, GNS Science of Applied Geology, Curtin Uni. of Technology
Predicting geophysical targets using reactive transport geochemical models Richard Chopping, PMD*CRC
Distinguishing microbial carbonates using in situ LA-ICP-MS vital trace element geochemistry: implications for biogenicity Dr. Gregory E. Webb, Queensland Uni. of Technology
The National Geochemical Survey of Australia: Overview and progress Dr. Patrice De Caritat, Geoscience Australia
Isotopic evidence for redox heterogeneity Hyperspectral Interpretation of Alteration Groundwater - an agent of geology in land in the late Archean and early Haloes Associated with Victorian Orogenic; and water salinisation in the southwest of Paleoproterozoic Hamersley Basin, Western Australia Gold Deposits Western Australia Jayath Da Silva, Department of Water Emily House, GeoScience Victoria Sue Golding, Uni. of Queensland
1705-172:5
Resource Assessment in the Drummond Basin, developing new concepts. Dr. Margaretha Scott, Geological Survey of Queensland
1725-174 5
Dryland salinity and geodiversity on the Southern Tablelands of NSW: the use of the EM (and AEM) technique for mapping and management? Glen Bann, Australian National Uni.
Interpretation of Aeromagnetic Datasets for Gold and Diamond Exploration: An Image-Analysis Approach Dr. Eun-Jung Holden, The Uni. of WA 1745-184?i
Happy Hour (Expo Area)
1800-2000
SEG Mentor Event (Johnny Walker Lounge)
KEYNOTE: A Workflow for Predictive Discovery - Thought Processes, Tools and Target Generation Mr. Paul Roberts, Predictive Discovery Pty Ltd
CONVENTION PROGRAM
19
monday 21 july
DYNAMIC EARTH (I) - Orogens and Basins: Indicators of Continental Process
Chair: Dr Russell Korsch
KEYNOTE The accretion model for orogenesis Prof. Gordon Lister, Australian National University
Prot Lyn Beazley, Uaiversity of Western Australia H ^ E N A M ^ S E S S I O H I : M A W S O N L E C i m £ - C h a i r : loo Hron^ly ' ~ Making Mountains: Geological drivers and environmental consequences Prof. Peter Cawood, IJniversltv of Western Australia MORNING TEA & POSTER PRESENTATIONS \7: Meeting Room 7 AS: Meeting RtMuii 8 DYNAMIC EARTH (2) - Archean DYNAMIC EARTH (3) - lectonics, the EARTH'S ENVIRONMENTS (4) - The processes and Crustal Evolution Landscape & Regolith Evolution 1 Geology of Australia's Offshore areas
Chair: Dr Martin van Kranendonk
A parametric study of overriding plate shortening and extension above subduction Continental materials on Earth by 4.5 Ga zones: Explaining the fonnation of the from Hf-Pb isotope systematics of the Jack Andes Hills zircons. Western Australia Dr. Wouter Schellart, Monash Dr. Tony Kemp, James Cook University University Orogen-scale tectonic shuffle zones Dr. Mamie Forster, The Australian National University
Chair: Dr David Falvey
KEYNOTE KEYNOTE The Early Mantle: Depletion, Plates, The tilting continent and other geomorphic Resurfacing Episodes and Isotopes signals of mantle flow beneath Australia Dr. Geoff Davies, Australian National Prof. Mike Sandiford, Uni. of University Melbourne
Surface area of emerged land and depth of mid-oceanic ridges in the Archean Nicolas Flament, The Uni. of Sydney
KEYNOTE Geochronologv of regolith-landform evolution in Australia: a brief review Prof. Brad Pillans, The Australian National Uni.
KEYNOTE Australia and the Integrated Ocean Drilling Program (lODP) Prof. Richard Arculus, Australian National Uni.
0940-1030
.
A10: Meeting Room 10 EARTH'S ENVIRONMENTS (1) Palaeo-environments
Chair: Dr Jonathan Clarke
1105 1125
KEYNOTE Ancient analogues for C 0 2 sequestration in coal measures, Gunnedah and Bowen Basins, Australia 1125-1145 Dr. Sue Golding, CSIRO Exploration and Mining
The University of the Sea and the benefits Foraminiferal tracers for climate and to learning of active participation|!in a water-quality changes in Pennian interior research cmise seas in northeastern Gondwana Kelsie Dadd, Macquarie Uni. Dr. David Haig, The Uni. of WA Quatemaiy evolution of Scott Reef, Northwest Shelf, Australia Dr. Lindsay Collins, Curtin Uni.
1030-1100 1100-1245
Age and stratigraphic constraints on the evolution of mega-lake Bungunnia: Insights into Plio-Pleistocene climate change in southem Australia Dr. Sandra McLaren, Uni. of Melbourne
1145-1205
1205-1225
1225-1245 Fonnation of Archean continental U-Pb isotopic age constraints on event Carbonate aeolianite systems within the Visualising landscape evolution with timing in the Southern Granulite Terrane, crust from an oceanic plateau in a non- SRTM data: regolith landform mapping Naturaliste-Leeuwin region of southwest New perspectives on the palaeoecology of subduction setting: the east Pilbara Cambrian phosphatic brachiopods Westem Australia: correlation with the India in the Tanami example Pleistocene-Holocene chronology of the Prof. Robert Henderson, James Cook Dr. Chris Clark, Curtin University of Dr. Martin Van Kranendonk, Dr. Richard Langford, Department of Geological Perth region Uni. Technology Industry and Resources Survev ofWA Diane Jorgensen, Geoscience Australia 1245-1345 LUNCH (Sponsored by Rio Tinto) & POSTER PRESENTATIONS 1345-1530 B6: M f ^ g Room 4 B7: Meeting Room 7 BK: Meeting Room 8 B'): Mceliiig Room 9 BIO: MeeUng Room JO DYNAMIC EARTH (1) - Orogens and DYNAMIC EARTH (2) - Archean DYNAMIC EARTH (3) - Tectonics, the EARTH'S ENVIRONMENTS (4) - The EARTH'S ENVIRONMENTS (1) Basins Indicators of Continental Process processes and Crustal Evolution Landscape & Regolith Evolution 1 Geology of Australia's Offshore areas Palaeo-environments
Chair: Dr Peter Southgate
Chair: Dr Angela Riganti
Chair: Dr Steve Rogers
Chair: Dr Lindsay Collins
Chair: Dr Jonathan Clarke
Milestones in the evolution 1350-1410 Drowned reefs in the Great Barrier Reef KEYNOTE: of the atmosphere with reference to and Hawaii: a new era in lODP coral reef climate change drilling KEYNOTE: Ophiolite in the Eoarchaean KEYNOTE: The Top Down paradigm Dr. Andrew Glikson, Australian Dr. Jody Webster, James Cook Uni. KEYNOTE: Geodynamics and Basin (>3700 Ma) Isua supracnistal belt " do plants control groundwater and National Uni. Evolution (Greenland): A 41 year-old debate weathering in!|semi-arid Australia? 1410-1430 Chemical composition of seawater Jane Blevin, FrOG Tech Pty Ltd Prof. Allen Nutman, Chinese Academy Dr. David Gray, CSIRO Exploration in Neoproterozoic and Paleozoic: a of Geological Sciences Multiphase palaeochannel development on and Mining contribution based on study of fluid the Great Ban ier Reef Shelf, Australia in halite fi-om Australia Dr. Raphael Wust, James Cook Uni. Profinclusions Tadeusz Peryt, Panstwowy Instytut Geologiczny 1430-1450 A Regolith and Landscape Evolution Sediment flux and composition Archean plate tectonic processes in Framework for Mineral Exploration Under changes Ice-rafting in the Mid-Ediacaran (-580 in canyons on a carbonateTimor stratigraphy reconstructed: Permian southwest Greenland Cover in the Northem Flinders Ranges siliciclasticilmargin: evidence fi-om Ma) Adelaide Geosyncline and Officer to Middle Jurassic - Frome Embayment, South Australia turbidite deposits along the Great Barrier Prof. John Myers, Curtin Uni. of Basin, South Australia Eujay McCartain, Uni. of WA Dr. Steve Hill, Uni. of Adelaide / CRC Reef margin Technology Dr. Victor Gostin, Uni. of Adelaide LEME Dr. Jody Webster, James Cook Uni.
Two New lODP Paleoceanographic Age constraints on the Sturtian Glaciation 1450-1510 Opportunities in the Timor Sea: in Adelaide Geoscyncline, South Australia Timor stratigraphy reconstructed: 155 Ma Dating high-grade metamorphic events New Insights into Landscape Evolution Drilling in the Nanyer Terrane by U-Pb SHRIMP of the Eucla Basin and Palaeochannels, Late Quatemar>' Paleoceanography and and the Pocatelo Fomiation of Idaho, USA to present Tracking Sea Level change from the Late indicate that there was no single Sturtian analysis of monazite and zircon Southern Australia Dr. David Haig, The Uni. of WA Miocene Snowball Dr. Janet Muhling, Uni. of WA Dr. Baohong Hou, C R C LEME PIRSA Bradley Opdyke, Australian National A/Prof. Mark Fanning, The Australian Uni. National Uni. U-Pb dating of monazites from Mt. Palaeoclimate driven eustatic signature 1510-1530 Timor stratigraphy deconstructed: Understanding the landscapes of the Perth of the Middle Devonian anoxic Pumillo Narryer metasedimentary rocks Neogene and ongoing collision Region Event from reef complexes of the Emanuel Dr. Tsuyoshi lizuka, The Australian Dr. Myra Keep, Uni. of WA Range, Lennard Shelf Bob Gozzard, Geological Survey of WA National Uni. Matthew Rolfe, Uni. of WA 1530-1600 AFTERNOOIN TEA & POSTER PRESENTATIONS C6: Meeting Room 4 1600-1745 C7: Meeting Room 7 C8: Meeting Room 8 C9: Meeting Room 9 CIO: Mefett^ Room 10 DYNAMIC EARTH (I) - Orogens and DYNAMIC EARTH (2) - Archean DYNAMIC EARTH (3) - Tectonics, the EARTH'S ENVIRONMENTS (4) - The EARTH'S ENVIRONMENTS (1) Basins Indicators of Continental Process processes and Crustal Evolution Landscape & Regolith Evolution 1 Geology of Australia's Offshore areas Palaeo environments
Chair: Dr Chris Clark
Chair: Dr Mark Pawley
Depositional age and provenance of the Palaeoproterozoic Hutchison Group, Southern Gawler Craton, South Australia Dr. Karin Barovich, Uni. of Adelaide
Metamoiphic evolution of the Eastern Goldfields Superterrane Dr. Ben Goscombe, pmd*CRC
Chair: Dr Charles Butt
Chair: Prof Richard Arculus
Chair: Dr Jonathan Clarke
Evidence for a massive H2S release 1605-1625 to surface waters at the Precambrian Cambrian (PC-C) boundary from Mo isotopes KEYNOTE: The dregs of weathering: Martin Wille, Australian National Uni. regolith mineralogy and chemistry Prof. Robert Gilkes, The Uni. of WA Geology of the submarine Mellish Rise off Facies pattems in carbonates of the Aptian 1625-1645 Northeast Australia Stage in Pamaiba Basin, Brazil and Dr. Neville Exon, Australian National insights from possible modem analogues Uni. Ricardo Jahnert, Curtin Uni. Mass wasting along the East Australian continental Slope Kriton Glenn, Geoscience Australia
U-Pb, Nd and Hf isotopic constraints on tectonic framework of the basin development and deformation in the An integrated Eastern Goldfields Superterrane Western Gawler Craton Karol Czarnota, pmd*CRC Katherine Howard, Uni. of Adelaide 1645-1705 Tectonothermal evolution of the Kim ban Granite-greenstone associations of the Episodic anoxic events recorded in the Orogeny, Southern Gawler Craton; - Irwin Hill region, Burtville Recognition and geological significance of Capel and Faust basins — geoscientific Pemiian-Triassic transition of the Meishan evidence for extrusional tectonics during Yamama Cenozoic paleosols in the regolith profile Terrane, Yilgam Craton, Australia assessment of an offshore frontier region section, South China: Sedimentary the development of a transpressional Dr. Sandra Romano. Geological Survey Dr. Mehrooz Aspandiar, CRC LEME, Riko Hashimoto, Geoscience Australia characterization and faunal response orogen Curtin Uni. of Technology ofWA Rian Dutch, Uni. of Adelaide Dr. Zhong Qiang Chen, Uni. of WA
The Kararan Orogeny - a link between the Neoarchean siliciclastic sedimentary successions of the central Yilgam: an Proterozoic North Australian and South equivalent to the Eastern Goldfields Australian cratons? Superterrane late-stage basins? Dr. Geoffrey Fraser, Geoscience Dr. Angela Riganti. Geological Survey Australia ofW4 Crustal to lithospheric-scale structure of the Capricorn Orogen from magnetotellurics Dr. Kate Selway, Uni. of Adelaide
How psoliths form Ravi Anand, CRC LEME
Coring of Cenozoic sequences of the northem Carnarvon Basin of Australia to answer global eustatic questions Dr. Neville Exon, Australian National Uni.
Large volumes of mafic magmatism atTecting Meso-Neoarchean crust, minerals from the Braeside lead Late Cretaceous dysoxia in a southem high Murchison Domain, Youanmi TeiTane, Secondary latitude deltaic to outer shelf succession, field, Pilbara, Western Australia Yilgam Craton, Western Australia the Otway Basin, southeast Australia Dr. Peter Downes, WA Museum Dr. Tim Ivanic, Geological Survey of A/Prof. Stephen Gallagher WA Happy Hour (Expo Area) SEG Mentor Event (Johnnv Walker Lounge)
1705-1725
1725-1745
1745-1845 1800-2000
20
CONVENTION PROGRAM tuesday 22 July
Illll
Australia's Energy Future (lYPE Theme: Resources - towards bustamable Use) Peter McCabe The Geological Histor>' of Climate Change Prof. Malcolm Walter, University of New South Wales
0945-1030
1030-1100
M O R N I N G TEA & POSTER PRESENTATIONS Meeting ftooin 3
1100-1245
RESOURCES (3) - Precompetitive RESOURCES (2) - Being Smarter GEOSCIENCE IN T H E SERVICE OF Geoscience Information - Window into with our Data includies Prospectivity SYSTEM (2) - The Pilbara Archean SOCIETY (2) - Geoscience Information the Future Analysis Drilling Project Chair: Dr Kerry Smith Chair: Dr Mark Biggs Chair: Dr Andrew Barnicoat Chair: Dr Kathleen Grev An overview of four international geosci- Quantitative assessment of undiscovered Moving from 2D to 3D geological maps of entific drilling projects, Pilbara Craton, gold endowment in central Victoria - procNew Zealand Western Australia, 2003 -2007 ess and implications KEYNOTE: Geoscience Australia, Dr. Mark Rattenbury, GNS Science Dr. Arthur Hickman, Geological Survey KEYNOTE: Auscope: Australian Vladimir Lisitsin, GeoScience Victoria Offshore Energy Security Program: an ofWA Earth Science Research Infomiation update of planned marine surveys and Infrastmcture New geophysical constraints on the extent initial results Predictive Modeling of gold deposits; Dr. Robert Woodcock, CSIRO of the Stawell and Bendigo zones in New Dr. Peter Southgate, Geoscience Walhalla - Woods Point region, Eastem Exploration and Mining South Wales Australia KEYNOTE: Geochemical evidence for Victoria Dr. Robert Musgrave, Geological the development of a fiilly-oxygenated Megan Hough, Monash Uni. Survey of NSW atmosphere-oceans and modem-style ecosystems by - 3 . 5 Ga A three-dimensional Weights of Evidence Central Victorian deep cmstal reflection Prof. Hiroshi b h m o t o , The Evaluating the geology and petroleum The Australian mineral occurrence data Model for the Dmmmond basin in NE seismic survey 2006: Implications for Pennsylvania State Uni., USA prospectivity of frontier exploration areas exchange model Queensland: quantitative assessment of mineralisation within the offshore north Perth Basin Adele Seymon, GeoScience Victoria controlling variables for epithermal Au Clive Willman, GeoScience Victoria Diane Jorgensen, Geoscience Australia Dr. Leonardo Feltrin, James Cook Uni. RESOURCES (5) - Energ>' Resources
1105-1125
1125-1145
1145-1205
1205-1225
1225-1245
A Tectono-sedimentary Mode! for Intracratonic Basin Fill: Examples from the Jurassic Surat Basin, Australia and the Lower Permian Ordos Basin, China Dr. Keyu Liu, CSIRO Petroleum
Bio-activity in the 3.46 Ga ferruginous Marble Bar Chert, Pilbara, Westem Australia Dr. Munetomo Nedachi, Kagoshima Uni.
Mapping mineral alteration associated with onshore hydrocarbon seepage using ASTER and Hyperion data Yuiia Novikova, Curtin Uni. of Technolog>'
Possible generation of MIF-S during hydrothermal alteration of organic rich sediments Prof. Hiroshi Ohmoto, The Pennsylvania State Uni., USA
Petroleum,Coal & Geotherraal Session (continued) Chair: Mr Graham Jeffress
SYSTEM (2) - The Pilbara Archean Drilling Project Chair: Dr Arthur Hickman Geochemical evidence for oxygenated oceans 3.46 Ga ago: REE geochemistry of the Marble Bar Chert recovered by the Archean Biosphere Drilling Project (ABDP) Dr. Kosei Yamaguchi, Precambrian Ecosystem Lab., XBR, J A M S T E C
1245-1345
L U N C H & POSTER PRESENTATIONS
1345^1530
m i t M m U ^ t
1350-1410
Collie Coal and the Clean Coal Technology Prof. Krishna Sappal, Curtin Uni. of Technology 1410-1430
Low-enthalpy geotheirnal systems driven by convection in fault zones Dr. Klaus Gessner, The Uni. of WA
Shallower Submarine Ecosystem at 2.7-2.8 Ga, Pilbara, Westem Australia Dr. Munetomo Nedachi, Kagoshima Uni.
Challenges in Fault Modelling of Coal Seams Mark Biggs, Anglo Coal (Dawson Management) Pt>' Limited
A volcanic caldera habitat for Earth's oldest stromatolites (c. 3.5 Ga) from the North Pole Dome, Westem Australia Dr. Martin Van Kranendonk, Geological Survev of WA
1430-1450
1450-1510
1510-1530
Subsurface alteration associated with Joining forces for (geoscience) knowledge actively forming seafloor massive sulfide - Groundwater and mineral exploration, mineralisation in the Brothers Caldera, same approach, different targets Kermadec Arc, New Zealand Dr. Jon Fawcett, Department of Dr. Christopher Yeats, CSIRO Primary Industries, Victoria Exploration and Mining Application of mineral exploration map- 3D time series mapping of hydrothermal plume behaviour associated with seafloor ping tools and concepts to groundwater massive sulphides in the Eastem Manus resource evaluation back-arc basin, Papua New Guinea Mr. Bruce Gill, Department of Primary Shannon Johns, C O D E S Industries, Victoria
Application of geomodeller in the Drummond Basin, Queensland Melanie Fitzell, Geological Survey of Queensland
The Neves Corvo (Portugal) massive Coastal Geographic Information System sulphide deposit: depositional instability for the Northem Agricultural Region of the in the Lombador lens, and the origin of Westem Australian Coast the sulphur Alexandra Stevens, Curtin Uni. Dr. Mike Solomon, C O D E S
Spatial Mathematical Models for Mineral The GeoSciML logical data model of geological concepts Prospectivity Mapping Bruce Simons, GeoScience Victoria Dr. Alok Porwal, Uni. of WA
A Perfect Sulphide Storm at Mt Isa Dr. Geoff Derrick, G M Derrick Geology
AFTERNOON TEA (Sponsored by Australian Journal of Earth Sciences)1 & POSTER PRESENTATIONS rniUm^Mmmi
Fracture network evaluation of Samana Anticline: Implication for assessing secondar>' fracture porosity of the proven reservoirs in the adjacent foreland basin, N W Pakistan Irfan Khan, MOOL, Oil&Gas Co.V.B Early to Middle Triassic stratigraphy of the offshore eastern Bonaparte Basin and Londonderry High, northern Australia John D. Gorter, Eni Australia Limited
1645-1705
Hydrocarbon prospects of Karak Siwalik Anticline, N W Pakistan: myths and facts Dr. Sajjad Ahmad, University of Peshawar, N.W.F.P. 1705-1725
1745-1845
KEYNOTE: Metallogenic Endowment of Cratons, Belts and Districts: Do Bull Elephants roam in Herds? Dr. Subhash Jaireth, Geoscience Australia
Geothemial Systems Analysis-A risk based Photosynthesis in a 3.5 Ga old shallow marine depositional environment; clues approach to exploring for geothermal from carbon and iron isotope systematics resources Mark van Zuilen, Laboratoire Graham Beardsmore, Hot Dry Rocks Geobiosphere Actuelle et Primitive Pty Ltd Institute
1625-1645
1725-174f
GEOSCIENCE IN T H E SERVICE OF RESOURCES (4) - Understanding Ore Systems SOCIETY (2) - Geoscience Information Chair: Dr Rob Hough Chair: DrKeny Smith
Geochemical Survey in the Highlands of Geosyntax: a new computing language for geology data Papua New Guinea Dr. June Hill, CSIRO Petroleum Benny Poke, MSSP-Geomap
RESOURCES (5) - Energy Resources Petroieun),Coal & Geothermal Session (continued) Chair: Ms Bree Goff 1605-1625
with our Data includies Prospectivity Analysis Chair: Mr Vladimir Lisitsins
3.2 Ga island arc oceanic sedimentary Geoscience Australia's Onshore Energy sequence: Preliminaiy result of the Dixon Security Program - the Geothemial Energy Island-Cleaverville drilling (DXCL-dri) Project Project Dr. Ian Lambert, Geoscience Australia Dr. Shoichi Kiyokawa, Kyushu Uni.
1530-1600 1600-1745
From takeover to take off: Issues in man3D ModeUing and the implications for aging data transfers and migration in||the Resource Assessment current frenetic M & A environment Elizabeth Amann & Sue Grennan, BHP Dr. Margaretha Scott, Geological KEYNOTE: Quantitative resource asBilliton Nickel West and Margaret Ellis, Survey of Queensland sessment - A precursor to prospectivity Geological Survey of WA analysis Get closer to the tmth... with hyperspecThe 34th Intemational Geological Don Singer, US Geological Survey, USA tral mineral maps from Queensland Congress - AUSTRALIA 2012: Progress Mai Jones, Geological Survey of and Prospects Queensland Dr. Ian Lambert, Geoscience Australia
KEYNOTE: Investigating Petroleum Systems Using Micron-scale Tracers within Sedimentary- Grains Dr. Peter Eadington, CSIRO Division of Petroleum Resources
SYSTEM (2) - The Pilbara Archean Drilling Project Chair: Dr Martin Van Kranendonk
KEYNOTE The Pilbara Drilling Project: Results and Perspectives Pascal Philippot, Institut De Physique Du Globe De Paris, France
RESOURCES (2) - Being Smarter GEOSCIENCE IN T H E SERVICE O F RESOURCES (4) - Understanding Ore with our Data includies Prospectivity Systems SOCIETY (2) - Geoscience Information Analysis (continued) Chair: Dr Chris Yeats Chair: Dr Kerry Smith Chair: Mr Don Singer Preliminary Results of a Self Organizing A prototype information model and Map Approach to the integrated Analysis markup language for geochemical and of Petrophysical Property Data from the geochronological information Ultramafic-Hosted Seagull PGE-Ni-Cu Prospect. Lake Nipigon, Ontario, Canada Dr Keith Sircombe, Geoscience KEYNOTE: The geodynamic setting and Stephen Eraser, CSIRO Exploration Australia magmatic controls on genesis of world & Mining class lOCG ore deposits Prospectivity Analysis in Action: The Dr. Nicholas Haywood, BHP Billiton The role of land use geoscience in urAuzex Resources Ltd. (AZX) Story as ban planning and development in the Applied to Granite Related Mineral Systems in Eastem Australia and New Goldfields of Westem Australia Zealand Chris Kojan, Geological Survey of WA Greg Partington, Auzex Resources Ltd Resource Mapping: A key ingredient for the mineral resources and development balancing act in South Australia Stuart Robertson, Geological Survey Branch, PIRSA Minerals and Energy Resources
Investigations of the Cultana Subsuite: An outcropping felsic intmsive - hosted Olympic Dam - style alteration system Stacey McAvaney, PIRSA
Multiple Sulfur and Carbon isotopic che- Using novel prospectivity mapping tools. Mineral potential mapping - geoscientific Self Organising Maps (SOMs). Fuzzy mostratigraphy of the 2.73 Ga carbonated advice for public policy: an example from Neural Networks (FNNs), and Radial Tumbiana Fomiation, new insights for the Western Australia Basis Functional Link Nets (RBFLNs), Fortescue excursion to evaluate the orogenic gold and lOCG Dr. Lee Hassan, Geological Survey Pascal Philippot, Institut De Physique potential of Finland ofWA Du Globe De Paris Prof. David Groves, Uni. of WA
Stmcture and hydrothermal alteration associated with the Dahongshan iron oxide - copper (gold) deposit, SW China Dr. xMatthew Greentree, S R K Consulting
Nano-aragonite associated with organic globules supports a biogenic origin of 2.7 Gyr old stomatolites Dr. Kevin Lepot, Institut De Physique Du Globe De Paris, France
Bayesian Network Classifiers for GISbased Mineral Prospectivity Mapping Dr. Alok Porwal, Uni. of WA
A Benchmark for Best Practice in Assessing Australia's Mineral Endowment Antony Mamuse, Uni. of W A & Curtin Uni. of Technology
Titanium-zircon minerals - using geoscience in Westem Australia to ensure future resource extraction Warren Ormsby, Geological Survey WA, Department of Industry & Resources
Happy Hour (Expo Area)
1830-2030
Student Careers Night (Expo Area)
1900-2200
GeoTrivia Night [Meeting Room 5 - Sponsored by Rio Tinto]
Geological setting, mineralisation and geochronology of Chairee epithermal gold-silver deposit, Phetchabun Province, central Thailand Abhisit Salam, CODES, Uni. of Tasmania
CONVENTION PROGRAM 21 tuesday 22 juiy :' I W M f l l i i i l t t
f
n
f
e
r
f
i
^
H
l
l
^
a
r
t
f
"
^
'
— -
^
^
»
" 0')00-I030 ()QU()-()945
Peter McCabe T he Geological History oi Climate Change Prof. Malcolm Walter, University of New South Wales M(3RN1NGTEA & POSTER PRESENTATIONS —
——
t>6: Meeting Hoom 4 M - Meeting Room » DYNAMIC EARTH (6) - The DYNAMIC EARTH (1) - Orogeiis and DYNAMIC EARTH (4) - Continental RESOURCES (1) - Exploration Phanerozoic: Young rocks, old procBasins Indicators of Continental Proces ^ Lithosphere Structure, Evolution and Strategies and Technologies the Upper Mantle esses? Chair Dr Ben Wade Chair: Mr Simon Beams Chair: Prof Brian Kennett Chair: Dr Tim Rawlins Vines 1 revisited: Neoproterozoic successions in Western Australia KEYNOTE: The Psychology of Decision Roger Hocking, Geological Survey ofWA KEYNOTE: Archean Lithospheric man- Making in Mineral Exploration - A Key . Isotopic evidence for continental growth tle: formation, composition and today's to Improving Return on Investment in oui Tectonic Controls on the Sequence during accretionary orogenesis in the Business Stratigraphic Architecture in a Non-marin refertilise remains Tasmanides, eastern Australia' Dr. Mike Etheridge, GEMOC Key Rift-basin Setting: An Example from the Dr. Suzanne O'Reilly, Macquarie Uni. Dr. Tony Kemp, James Cook Uni. Centre, Department of Earth and Tertiary Bohai Bay, East China Dr. Zhu Hongtao, China Uni. of Planetary Sciences Geosciences/CSIRO Petroleum Resources Provenance of metasedimentary rocks Integrated isotope and trace element analy _ Technology and Integration: Improving ex from the Entia Dome, eastern Arunta Provenance of Ophiolitic Sand: Region, central Australia: a combined ses of detrital minerals from the FranklancJ ploration success - the Australian Mineral Fields Philosophy U-Pb SHRIMP, LA-ICPMS and Sm-Nd Comparison of Ancient and Modem Sand River (SW Australia) Marcus Willson, Australian Mineral isotope study. Melissa Murphy, Macquarie Uni. Dr. Bruno Dhuime, Uni. of Bristol Dr. Benjamin Wade, Uni. of Adelaide Fields Ltd Basement faults control over salt-driven tectonics in the Central Flinders Ranges, South Australia Dr. Guillaume Backe, CMXUC Uni. of Adelaide
Integra Mining's Exploration Strategy and Discoveries - Does one size fit all? Chris Cairns, Integra Mining Ltd
In situ U-Pb, O, and Hf isotope measurements of I- and S-type granites from the Beiridale and Kosciuszko Batholiths Dr. Ryan Ickert, Australian National Uni.
Does the Capricorn Orogen control seis- Elastic thickness of Precambrian cratons A Potential New MVT Province in Laos micity in the Carnarvon Basin? - a global study Dr. Myra Keep, Uni. of WA Dr Jon Kirby, Curtin Uni. of Technologj Ian Mulholand, Rox Resources Limited
The Sierras Pampeanas - Puna basin connection: Ordovician cmstal thinning and back-arc basin fonnation at the SW Gondwana margin Dr. Steffen Buttner, Rhodes Uni.
TerraneChron" approach to the crustal evolution studies and implications for continental growth Dr. Elena Belousova, Macquarie Uni.
0945-1030 1030-1100 1100-1245 EARTH'S ENVIRONMENTS (4) - Th( G eology of Australia's Offshore areas Chair: Dr Neville Exon Sequence Stratigraphy and Seismic Facie;5 of the Eucla Basin, Great Australian Bight South Australia. Sian Smith, Uni. of Sydney Ritter Volcano, West Bismarck Arc: tsunamigenic collapse and peridotite xenolith locality Prof. Richard Arculus, Australian National Uni.
1105-1125
1125-1145
Tectonics and volcanism associated with 1145-1205 the propagation of backarc spreading and associated rifting of an island arc: An example from the southeast margin of the North Fiji Basin Leonid V. Danyushevsky, CODES 1205-1225
1225-1245
LUNCH & POSTER PRESENTATIONS 1245-1345 m i m ^ ^ s ^ i 1345-1530 DYNAMIC EARTH (6) - The DYNAMIC EARTH (1) - Orogens and DYNAMIC EARTH (4) - Continental RESOURCES (1) - Exploration EARTH'S ENVIRONMENTS (2) Lithosphere Structure, Evolution and Phanerozoic: Young rocks, old procBasins Indicators of Continental Process Strategies and Technologies Paleoclimate Research the Upper Mantle esses? Chair: Dr Geoff Fraser Chair: Mr Marcus Willson Chair: Dr Ken Lawrie Chair: Dr Graham Bens Chair: Dr Robert Mussrave A record of late Palaeoproterozoic 1350-1410 metamorphism and reworking in the Cadney Metamorphics, Strangways KEYNOTE: The Phanerozoic: Metamorphic Complex, central Australia KEYNOTE: Lithospheric Edges and Reconciling modem plate tectonics with Dr. Ben Wade, Uni. of Adelaide Sutures KEYNOTE: Exploration Science KEYNOTE ancient orogenic systems and cmstal Proterozoic crustal architecture and Prof. Brian Kennett, Research School of Dr. Andy Barnicoat, Pmd*CRC Martin Williams, University of Adelaide 1410-1430 growth evolution in the Mount Isa region: new Earth Sciences Prof. William Collins, James Cook Uni. insights from seismic reflection profiling Dr. George Gibson, Geoscience Australia Using time-constrained facies belts and High-Mg monzodiorite-tonalite ± syenite Accretion of a Late Ordovician island arc 1430-1450 Cenozoic biogeographic evidence for The Shear Wavespeed Structure of the sequence models to conelate the Western intrusions, skaras, and gold deposits in terrane into the northern Tasmanides and West Pacific Warm Pool formation and the and Eastern successions of the Mt Isa Australian Lithosphere: Is it Compatible initiation of the Kuroshio and Leeuwin the Eastern Goldfields Province, Yilgam Inlier: implications for fluid migration its implications for orogenesis with Physically Based Models? Current craton, Western Australia Dr. Peter Southgate, Geoscience Prof. Robert Henderson, James Cook Dr. Stewart Fishwick, Uni. of Leicester A/Prof. Stephen Gallagher, Uni. of Australia Andreas Mueller, Consultant Uni. IVfplhniirnp New geochronological constraints on A comparative gold prospectivity assess- Palaeozoic granites in central Queensland: 1450-1510 Distribution and ecology of benthic ment of the Lake Victoria Greenstone sedimentation in the Georgetown Inlier: a transect across the Thomson - New Characteristics of the Australian Crust foraminifera in the Coorong Lagoon and Terrane, NW Tanzania and the Eastern Correlations with the Mount Isa Inlier England Orogen boundary; implications of from Seismic Reflection Profiling Goldfields Province, Western Australia the role of cmstal composition for granite adjacent waters, South Australia; to aid Dr. Narelle Neumann, Geoscience Dr. Bruce Goleby, Geoscience Australia palaeo- reconstmctions Dr. Frank Bierlein, Uni. of WA & Ivo formation Australia Prof. John Cann, Uni. of Adelaide M.A.Vos, Resolute Mining (Tanzania) Ltd Emma Mathews, Geoscience Australia An integrated sedimentological, 1510-1530 Increasing the scope of mineral prospec- Age and provenance of the Owen Stanley WOMBAT: An evolving seismic array geochemical and geochronological Metamorphic Complex (East Papuan tivity in the Cobar-Bourke region, New analysis of Georgetown: Consfraints experiment in Australia Composite Terrane) in Morobe Province, South Wales on basin development and paleo Dr Nicholas Rawlinson, Australian Papua New Guinea Mr. Steven Trigg, New South Wales reconstructions National Uni. Dr. Robert Findlay, Montagu Minerals Department of Primary Industries Alexis Lambeck, Geoscience Australia Mapping Ptv I ,td AFTERNOON TEA (Sponsored by Australian Journal of Earth Sciences) & POSTER PRESENTATIONS 1530-1600 mimmm^Bmmi F9: Meeting Room 9 1600-1745 FIO: Meeting Room 10 DYNAMIC EARTH (4) - Continental DYNAMIC EARTH (6) - The EARTH'S ENVIRONMENTS (2) Lithosphere Structure, Evolution and RESOURCES (1) - Resources Phanerozoic: Young rocks, old procPaleoclimate Research the Upper Mantle Chair: Dr Frank Bierlein esses? Chair: Dr Ken Lawrie Chair: Dr Bruce Golebv Chair: Dr Steffen Buettner 1605-1625 From the strengthening, emergence and Potential field models of the Bancannia erosion of continents in the Neoarchaean, The Mt. Mulga barite-iron-oxide-copper- Trough - Koonenberry Belt system, NSW: Cenozoic carbonate response to climatic gold mineralisation, Olaiy Domain, South change due to a tectonic-induced latituto the coupling of Earth's geochemical tectonics of a rifted arc Australia dinal shift reservoirs Dr. Robert Musgrave, Geological Martin Griessmann, Uni. of Adelaide Dr. Moyra Wilson, Curtin Uni. Dr. Patrice Rey, The Uni. of Sydney Survey of NSW Strength of high-geotherm lithosphere: Weak, strong, or failing? Shane Richardson, The Uni. of WA
Exploring for Porphyry Cu-Au-Mo in the Gilmore Fault Zone at Temora, NSW Martin Scott, Goldminco
Anisotropy of Lithosphere Strength Dr. David Healy, Curtin Uni. of Technology
Predicting compositions of white micas in lode gold systems: results of numerical modelling Dr. James Cleverley, CSIRO EM
(Irustal architecture of Central Victoria: results from the 2006 deep crustal reflection seismic survey Dr. Russell Korsch, Pmd*CRC The southwestern Laurentian lithosphere in the northern Rockies, USA: crustal provinces, plutonic imaging, and seismic structure 1'rof. David Foster, Uni. of Florida, USA
1625-1645 Attenuation of high-strain zones in the Sea level reconstmctions from fossil coral Wyangala Granite, Eastem Lachlan Fold reefs along the Cape Range coast, Western Australia Belt, NSW, Australia. Dr. Andrea Dutton, Australian National Lloyd White, Geoscience Australia Uni. Tectonic extrusion of the Thomson Benthic Foraminifera assemblages in the ^1645-1705 Orogen: Australia-Asia equivalent of northern Spencer Gulf, South Australia India-Asia defomiation - further evidence for Holocene sea-level Dr. Chris Klootwijk, Australian changes National Uni. Mary-Anne Binnie, Uni. of SA 11705-1725 Geological stmcture of the Kumbmf IVIWP-1A and its implication for the moisvolcanic arc (Bismarck Range, PNG ture regime change over Borneo - evidence Highlands) from peat archives Dr. Peter Kovac, Mssp-Geomap Dr. Raphael Wust, James Cook Uni. 1725-1745 Mirror Images in East and West Papua Bryan Ruxton, Uni. of Canberra
Happy Hour (Expo Area) Student Careers Night (Expo Area) GeoTrivia Night [Meeting Room 5 - Sponsored bv Rio Tinto]
—
i 745-1845 j830-2030 i 900-2200
22
CONVENTION PROGRAM Wednesday 23 July
0900-1030
—
0900-0945 0945-1030
Thc Yarragadec Aquifer (lYPE Theme: Groundwater - towards sustainable use) Mr. Philip Commander, Department of Water (WA) The Tsunami Risk to Australia and what is being done to mitigate it (lYPE Theme: Hazards - minmiizing risk, maximising awareness) Dr. Barrv Drummond, Geoscience Australia iVllxeu / v y v a i u s
1030-1105
1130-1315
( ; I : Meeting Room 5 RESOURCES (5) - Energy Resources Uranium Session Chair: Mr Marcus Harris
ihjus;
MORNING TEA (Sponsore*I by Gnomic Exploration Services) & PO STER PRESENTATIONS CA' Rnnm 6 G3; Meeting Hoom Jt
1105-1130
EVOLUTION OF LIFE & SOLAR SYSTEM (3) - Evolution of Life in the Proterozoic and Phanerozoic Chairs- Drs Kathleen Grev & Gres Webb
CANNING BASIN SYMPOSIUM (X) - Geochemical Basin dynamics and resource implications Chair: Prof Peter Cawood
G5: l i B s A ^ R o o n i 1
GEOSCIENCE IN THE SERVICE OF RESOURCES (4) - Understanding Ore Systems SOCIETY (4) - Geohazards Chair: Dr Steve Rogers Chair: Dr Barry Drummond
A new view of hypogene and supergene gold: Clues for ore paragenesis and exploration KEYNOTE: Rupture Characteristics Dr. Robert Hough, CSIRO Exploration ICEYNOTE: Australia's Uranium of Recent Tsunamigenic Earthquakes in and Mining Aiictraliicia and /AU JLI ulCtSltl, FctimfltpH J—JLllllCltWU frnm XlVJlll Sftismic IA J.AV* Redox-controlled Supergene Gold Dr. Phillip Playford, Geological Survey Trace element geochemistry of 1155-1215 Global Context Sea Level Data Enrichment within the Sunrise Dam ofWA J Dr. Ian Lambert, Geoscience Australia Neoproterozoic stromatolites: a tool for Or. Phil Cummins, Geoscience Australia Palaeochannel Deposit, Laverton, Western interpreting accretionary processes Australia Dr. Gregory E. Webb, Queensland Uni. Dr. Louisa Lawrance, The Uni. of WA of Technologv 1215-1235" The significance and origin of the Do strain-rates in deep ductile shear zones The composition and crystallography of biomarker crocetane in Devonian source reflect seismogenesis at surficial levels of rocks and crude oils (Western Canada gold: implications for ore genesis Uranium mineralising systems: a the same movement zone? Sedimentary Basin and Canning Basin, Dr. Charles Butt, CSIRO Exploration & continuum of deposit styles? WA) Dr. Mamie Forster, The Australian KEYNOTE: Perylene: a molecular Mining (CRC LEME) Dr. Roger Skirrow, Geoscience Australia Ercin Maslen, Curtin Uni. of National Uni. marker for lignin degradation and a signal Technology for the rise of vascular plants 1235-1255 Earthquake magnitude in the context of Prof. Kliti Grice, Curtin Uni. of Cyclicity in Late Devonian conglomerates, rupture harvesting efficiency in different Transport and deposition of colloidal gold Exploration for Sandstone-Type Uranium Technology Lennard Shelf, Canning Basin, W.A. in saprock fractures Deposits in Tertiary Palaeochannels in the geodynamic environments Roger Hocking, Geological Survey Dr. Ryan Noble, CSIRO South of Western Australia Prof. Gordon Lister, Australian OfWA Prof. Mike Dentith, Uni. of WA National Uni. 'alaeoproterozoic hydrocarbons associated with uranium and gold deposits Dr. Adriana Dutkjewicz, The Uni. of KEYNOTE: Devonian reef complexes of Sydney the Canning Basin: 50 years of research
1255-1315
Controls on syndepositional fracture patterns, Devonian reef complexes. Canning Basin, Western Australia Dr. Edmund Frost, ConocoPhillips - Subsurface Technology
Sedimentary Uranium in South Australia's Frome Embayment: A case history of the first discoveries, 1967-1974 Dr. Barrv Cooper, Primary Industries & Resources South Australia
Evidence for competing movement patterns influencing the evolution of the Sagaing-Sumatra wrench fault system Abhijit Deonath. The Australian National Uni.
Architecture of Archean greenstones at St Ives: a vector to Au and Ni ore Dr. Richard Squire, Monash Uni.
LUNCH & POSTER PRESENTATIONS
1315-1415
H2: Meeting Romn 2 EVOLUTION OF LIFE & SOLAR SYSTEM (3) - Evolution of Life in the Proterozoic and Phanerozoic Chair: Dr Kathleen Grev
H4: M ^ t o ® Room 6
eS: Meetij^Room I
CANNING BASIN SYMPOSIUM (X) - Geochemical Basin dynamics and resource implications Chair: Mr Roeer Hockins
GEOSCIENCE IN THE SERVICE OF SOCIETY (4) - Geohazards Chair: Mrs Beatriz Estrada
RESOURCES (6) lAGOD - Mineral Resources of Western Pacific session Chair: Dr Nigel Cook
Discovery of Paleodictyon in brackish water environment from the Permian of the Carnarvon Basin, Western Australia Zhongwu Lan, Uni. ofWA
Canning Basin oil and gas potential Neil Thompson, ARC Energy Limited
Volcano and Earthquake Risk in the AsiaPacific Region Mr. Jonathan Griffin, Geoscience Australia
Restoration of marine ecosystems following the Permian-Triassic mass extinction in Gondwanan interior sea Dr. Zhong Qiang Chen, Uni. of WA
The Cambro-Ordovician, the Centralian Superbasin (Part 2) and trans-Gondwanan Seaways Robert S. Nicoll, Australian National Uni.
The role of geoscience in developing the Indian Ocean Tsunami Warning System Dr. Jane Cunneen, Intergovernmental Oceanographic Commission of UNESCO
1500-1520
Provenance of Paleozoic sandstone in Molecular and isotopic evidence for a RIO Tinto Iron's concealed high grade microbial response to the Triassic-Jurassic the Canning Basin using SHRIMP U-Pb #2 lens; product of hypogene and dating of detrital zircons mass extinction hydrothennal fluid processes, Paraburdoo Dr. Peter Haines, Geological Survey Dr. Kenneth Williford, Curtin Uni, of Western Australia. ofWA Technology Warren Thome, Uni. of WA
Toward an understanding of tsunami risk in Tasmania Colin Mazengarb, Mineral Resources Tasmania
Geomorphology, crocodiles and mineralisation in Morobe Province, PNG Dr. Robert Findlay, Montagu Minerals Mapping Pty Ltd
1520-1540
The Permian Conodont biostratigraphy of Tsunami hazard in south-eastern Australia: Position of the end-Permian mass South Jimblebar,Newman - an integrated preliminary findings from palaeotsunami Western Australia - an update extinction level and Permian Triassic team approach to an iron ore discovery. investigations on the NSW coast Robert S. Nicoll, Australian National boundary in Australia Mr. Steve Wilson, BHP Billiton Iron Ore Prof. Ian Metcalfe, Uni. of New England Amy Prendergast, Geoscience Australia Uni.
Metallogenesis of the Koonenberry Belt, northwestern New South Wales Phil Gilmore, Geological Survey of NSW, NSW Department of Primary Industries
1540-1600
Global significance of stable carbon, sulfur The giant Carajas jaspilite-hosted Three Dimensional Modeling of Natural and hydrogen isotope signals together iron deposits: geological setting, fluid Hazards Using Geographic Information with higher plant derived components of geochemistry and genetic model Systems sedimentary organic material from the Steffen Hageman, Centre for Dr. D. John Prabaharan, Department Permian/Triassic boundary Exploration Targeting, School of Earth for Planning and Infrastructure Brigit Nabbefeld, Curtin Uni. of Technology and Geographical Sciences, Uni. of WA AFTl 5RNOON TEA & POSTER PRESENTAl IONS
1415-1600
i l l : Meeting Room 5 RESOURCES (7) - Mineral Resources Iron Ore Chair: Mr Marcus Harris
1420-1440
1440-1500
1600-1630 1630-1815
KEYNOTE: Fortescue Metals Group Ltd - Creating Shareholder Value from Exploration Stuart Robinson, Fortescue Metals Group Ltd
MrMMltef
Rooms
12: M f i ^ M t t g R o o m 2
i j : iVieeniig K o o m j
RESOURCES (2) - Exploration StrateRESOURCES (5) - Energy Resources gies and Technologies & Being Smarter GEOSCIENCE IN THE SERVICE OF SOCIETY (4) - Geohazards Petroleum, Coal & Geothermal Session with our Data Chair: Miss Amy Prendergast Chair: Dr Peter Southgate Chair: Dr Peter Collins
The meeting of two fluids: Mechanisms for fluid mixing in the crust Dr. Heather Sheldon, CSIRO
Key Geochemical Parameters of the Regolith Kenneth McQueen, CRC Leme
1635-165;
KEYNOTE An Integrated Approach to Geological Screening for Sequestration Potential 1655-171: - Examples from the Darling and Sydney Keys to the production of Eastern Yilgam Basins, New South Wales Au deposits: Mixing oxidized and reduced' Jane Blevin, FrOG Tech Pty Ltd mantle fluids John Walshe, Pmd*CRC, CSIRO xMining and Exploration, ARRC 1715-173:
1735-175
14- M e e t i n g R o o m 6
RESOURCES (1) - Mineral Resources (Fluid Mixing and Gold Session) Chair: Dr Jon Hronsky
An organogenic model for carbon sequestration Dr. David Wright, University of Leicester
Gem comndum sources. West Pacific margins, links to former spreading rifts Dr. Lin Sutherland, Uni. of Western Sydney
I5:M«ettetRoom 1
RESOURCES (6) lAGOD Mmeral Resources of West* rn Paciht Session Chair: Mr lan Graham
The Tolukuma mine, PNG; the structural Understanding natural hazards using field anatomy of a classic intra-volcanic epithergeology and geochronology mal gold system Dr. Mark Quigley, The University of Dr. Robert Findlay, Montagu Minerals Melbourne Mapping Pty Ltd
Three-dimensional magnetotelluric imag- Sediment quality As a factor of the distri- Trace elements in sphalerite: concentration levels and mode of incorporation ing of the Central-Western Gawler Craton bution of damage at Bam,iran earth quake Khalil Rezaei, Lmu University German;^ Nigel Cook, Natural History IMuseum Stephan Thiel, Adelaide University
P-T-X Conditions of Fluids in the Sunrise Victoria's Proterozoic basement intimatel>^ New zircon U/Pb dating from the Mt Coo-' Towards a better assessment of the seismii Ion mineral district, northern Drummond Dam Gold Deposit, Western Australia: controlled the distribution of its coastal hazard in the southwest of Western Implications for the Interplay between Basin, Queensland, and implications for petroleum basins and the subsequent Australia Deformation and Fluids in Orogenic Gold regional exploration targetting Cainozoic landscape evolution of the Beatriz Estrada, University of Western Systems Dr. Robert Findlay, Montagu Minerals highlands Australia Dr. Timothy Baker, James Cook Mapping Pty Ltd David Taylor, DPI - GeoScience Victoris1 University ^ Keys to the production of Eastern Yilgam• Au deposits: Chemical and structural architecture controls on sites of fluid mixing' Peter Neumayr, Pmd*CRC, CET, University of Western Australia
KEYNOTE: The Yanshanian tectonothermal event in China and associated mineral systems Dr. Franco Piranjo, Geological Survey OfWA
Gold lode deposits in Orogenic Belts of Russian Segment of the Pacific Rim Prof. Nikolay Goryachev
The Paddy's Flat Gold District (MurReconciling neotectonic and seismic recur•- Isotopic Tracers of Fluid Sources in the chison, W.A.): Insight into rheologically Lachlan Orogen rence rates in SW Australia and stmcturally controlled gold minerDr. Terry Mernagh, Geoscience Dr. Mark Leonard, Geoscience alisation Australia Nick Thebaud, Center for Exploration Australia Targeting, UWA
1755-181
^ Breccia mechanics as an explanation for extreme geochemical micro-gradients ancJ fluid mixing in the genesis of iron-oxideCu-Au deposits Prof. Nick Oliver, James Cook University 1930-230( D 1
Carbon Dioxide Storage Sites: from Prospects to Pilots Tess Dance, C 0 2 C R C CSIRO Petroleum
Provenance of gold in Mesozoic mesothermal mineral deposits in New Zealand Dr. Christopher Adams, GNS Science
uiHiier
ivcvci j)
—
CONVENTION PROGRAM 23 Wednesday 2 3 july m » - Intern W i S T P a r W I i l l n e f H i
]0900-103(
The Yarragadee Aquifer (1YPE Theme: Groundwater - towards sustainable use) Mr. Philip Commander, Department of Water (WA) The Tsunami Risk to Australia and what is being done to mitigate it (lYPE Theme: Hazards - minimizing risk, maximising awareness) Dr. Barry Drummond, Geoscience Australia
10900-0945
Mixed Awards (35 mins) MORNING TEA (Sponsored by Gnomic Exploration Services) & POS TER PRESENTATIONS
1030-1105 1105-1130
<;6: Meeting Kooin 4 DYNAMIC EARTH (7) - Plate Tectoni( Processes & the Dynamic Mantle Chair: Dr Craig O'Neill
(;7: Meeting Room 7 DYNAMIC EARTH (8) - The Proterozoic: Intercontinental vs Accretionary process Chair: Dr Ian Tvler
GS: Meeting Room S EVOLUTION OF LIFE & SOLAR SYSTEM (4) - Formation of the Solar System Chair: Dr Marc Norman
KEYNOTE: Proterozoic accretionary processes of Australia and comparisons with Laurentia. Dr. Peter Betts, Monash Uni.
KEYNOTE: The formation and early evolution of the solar system Dr. Raquel Salmeron, Mt Stromlo Observatory
• 0945-1030
1130-1315
t;9: Meeting Room 9 D Y N A M I C EARTH (5) - Mantle Melts; A Spectrum of Process Chair: Dr Tony Crawford
1135-1155
KEYNOTE: What drives major episodic reorganisations of the plate-mantle Dr. Dietmar Muller, The Uni. of Sydney
KEYNOTE: Mantle melting Dr. Nick Arndt, Universite De Grenoble 1155-1215 (Sponsored by Geoconferences (WA) Inc.]
Three-dimensional morphology of magmatic sulphides sheds light on ore Nd isotopes and their utility in crustal Fonnation of the Inner Solar System: new formation, mantle melting and segregation evolution studies in Proterozoic Australia insights revealed by spacecraft data of the Earth's core Dr. Karin Barovich, Uni. of Adelaide Andrew Prentice, Monash Uni. Dr. Marco Fiorentini, Centre for Exploration Targeting, The Uni. of WA
1215-1235
Deep subduction dynamics and its expression in plate motions Dr. Fabio Antonio Capitanio, Monash Uni.
Integrating deep Earth dynamics in paleogeographic reconstructions of Australia Dr. Christian Heine, EarthByte Group
The Glenburgh Terrane: a record of subduction and collision in the Paleoproterozoic Capricorn Orogen of Western Australia Dr. Simon Johnson, Geological Survey ofWA
Experimental constraints on the slab component of arc magmas Dr. Joerg Hermann, Research School of Earth Sciences, The Australian National Uni.
1235-1255
On the dynamics of active continental margins Dr. Patrice Rey, The Uni. of Sydney
Reinteipretation of high-temperature metamorphism within a continental back-arc setting for the Broken Hill Block, NSW Dr. Caroline Forbes, Uni. of Adelaide
Dating Fractionation of Refractory and Early History of Planet Earth from Volatile Elements in the Protoplanetary Combined l42-143Ndand 176Hf Isotopic Disk Signatures Dr. Vickie Bennett, Australian National Dr. Yuri Amelin, The Australian Uni. National Uni. LUNCH & POSTER PRESENTATIONS
1255-1315
DYNAMIC EARTH (7) - Plate Tectonic Processes & the Dynamic Mantle Chair: Dr Dietmar Muller
H7:Mi«ft^Roora7 DYNAMIC EARTH (8) - The Proterozoic - Intercontinental vs Accretionary process Chair: Dr Ian Tvler
KEYNOTE:Subduction zone dynamics on Earth: Insight from geodynamic models, kinematic calculations and observations Dr. Wouter Schellart, Monash Uni.
KEYNOTE: The Proterozoic: Hiding Archean in the basement Prof. William Griffin, Macquarie Uni.
HK: Meeting Room N 119: Meeting Room 9 EVOLUTION OF LIFE & SOLAR DYNAMIC EARTH (5) - Mantle Melts: SYSTEM (5) - Early Planetary A Spectrum of Process Differentiation Chair: Dr Steven Beresford Chair: Dr David Nelson Chronology of the Early Solar System through Short-lived and Long-lived Chronometers Dr. Trevor Ireland, Australian National KEYNOTE: Large Igneous Provinces, Uni. Mantle Plumes and Crust Generation Prof. Chris Hawkesworth, Uni. of Extremes of Igneous Fractionation in Bristol the Moon
H6: Meeting Room 4
Dust to Planets - what have we learned from Genesis and Stardust Samples? Judith Allton, NASA Johnson Space Center
1315-1415 H10: Meeting Room 10
1415-1600
EARTH'S E N V I R O N M E N T S (3) - Environmental Hazards Chair: Dr Colin Pain 1420-1440
KEYNOTE: Recent advances in the application of hydrogeophysics and regolith geoscience for groundwater and salinity mapping and management Dr. Ken Lawrie, Geoscience Australia
1440-1500
Dr Jeffrey Taylor, Hawaii Institute of Geophysics and Planetology The emergence of steady-state plate tectonics in dynamic mantle models Dr. Craig O'Neill, Macquarie Uni. Multi-scale Earth System Dynamics Coupling Mechanics with Chemistry Prof. Klaus Regenauer-Lieb, UWA and CSIRO E&M
Formation of the eclogite hosting 2.0 Ga Llsagaran Orogenic belt, Tanzania Rachael Brick, Uni. of Adelaide
Early evolution of Earth and Moon Dr. Alexander Nemchin, Curtin Uni. of Technology
1500-1520 The extent and distribution of the Architecture of an Entrenched Valley Fill, Kalkarindji Large Igneous Province Murray River Dr. Lena Z. Evins, School of Earth and Dr. Jonathan Clarke, C R C LEME/ Geographical Sciences, The Univ. of WA Geoscience Australia
Mineralogy of Mesoproterozoic high heat 1520-1540 A New Type of Basaltic Eucrite: Clues to Systematic PGE depletion in early- to Using A E M imagery to map palaeo strand producing granite and mafic dyke from Early Differentiation of Igneous Asteroids mid- Archean komatiites from the Pilbara lines in the Loxton Parilla Sands, Murray Mount Painter Province Katherine Bermingham, Australian and Kaapvaal cratons River corridor, Victoria Kamonporn Kromkhun, The Uni. of National Uni. Dr. Wolfgang Maier, Uni. of WA David Gibson, Geoscience Australia Adelaide
How to recognise flat-slab subduction and foundering: an example in orogenic, magmatic and basin records of Mesozoic South China Prof. Zheng-Xiang Li, Curtin Uni. of Technology
A spectrum of Hadean geodynamics from diamond stability constraints Dr. Craig O'Neill, Macquarie Uni.
Evidence for a Mesoproterozoic hotspot track in eastern and central Australia Dr. Peter Betts, Monash Uni.
AFTERNOON TEA & POSTER PRESENTATIONS 12: Mfe^hlg Room 7 DYNAMIC EARTH (8) - The Proterozoic: Intercontinental vs Accretionary process Chair: Dr Martin Hand Assembling the western North Australian Early Archean tectonics and the start of Craton: Linking the King Leopold, Halls modem subduction Creek, Granites-Tanami and Arunta Dr. Martin Van Kranendonk, Geological orogens Survey of Western Ausatralia Dr. Ian Tyler, Geological Survey of Western Australia DYNAMIC EARTH (7) - Plate Tectonic Processes & the Dynamic Mantle Chair: Prof Klaus Regenauer Lieh
13 Meeting Room 8
14 Meeting Room 9
EVOLUTION OF LIFE & SOLAR DYNAMIC EARTH (5) - Mantle Melts: SYSTEM (6) - Mars - Water and Rocks A Spectrum of Process Chair: Prof. Jeffrey Taylor Chair: Dr Steven Beresford
1540-1600 Customised products derived using airborne EM and hydrogeological data to assist in land use management along the Mun-ay River in New South Wales and Victoria, Australia Dr. Kok Piang Tan, Geoscience Australia 1600-1630 15: M t i ^ R o o m 10
1630-1815
EARTH'S ENVIRONMENTS (3) - Environmental Hazards Chair: Mr Ian Graham 1635-1655
Little time for a lot of LIP: Relative timing
of magmatism and defonnation during the Input of geomorphic and regolith mapping c. 1070 Ma Giles Event in the Musgrave to the Interim Biogeographic RegionalisaKEYNOTE:Mineral Precipitation in Complex of Western Australia tion for Australia (IBRA) Porous Media: Laboratory Diffusion Dr. Paul Evins, Geological Survey of Dr. Colin Pain, C R C LEME Experiments as Analogues for Concretion Western Australia Extension in lower crustal granulite Formation in Utah and on Mars 1655-1715 Geochemical and Nd isotopic signatures facies mafic orthogneisses of the Biranup Laura Barge, Universitv of Southern Integrating remote-sensing with airborne Thermochemical controls on the subducof mafic dykes in the western Musgrave Complex (Albany-Fraser Orogen), Bremer California electromagnetics for vegetation and crop tion of oceanic plateaus Complex Bay, Western Australia health along the River Murray Corridor Wendy Mason, Monash University Dr. Heather Howard, Geological Survey Miriam Barquero-Molina, Department Dr. Vanessa Wong, Geoscience Australia of Western Australia of Geological Sciences 1715-1735
Discovery of a fossil slab in the lower The c. 1680 Ma Dalyup Gneiss of the mantle below the Tasman Sea using plate Albany-Fraser Orogen, Western Australia: reconstructions and mantle tomography What is it, and where did it come from? Dr. Wouter Schellart, Monash UniDr. Catherine Spaggiari, Geological versity Survey of W estern Australia
The Dalhousie Mound Spring Complex as a guide to Martian Landforms and Processes Dr. Jonathan Clarke, Mars Society Australia
Plate vs. plume: clues from Neoproterozoic geodynamic record Prof. Zheng-Xiang Li, Curtin University of Technology
Variability in landscape evolution rates, and the preservation of regolith David Gibson, Geoscience Australia
Elastic Behaviour of Earth's Lower Mantle The crustal evolution of the Musgrave Solids Under High Compression' Province Prof. S. C. Goyal, R.B.S. College, Ailsa Schwarz, University of Adelaide Bichpuri, Agra
Layered units at the Martian dichotomy and their geological significance Dr. Graziella Caprarelli, Sydney University of Technology
Comparing isotopic and trace element geochemistry of the St Peter Suite with later gabbroic intrusions Neil Chalmers, PIRSA
^'redicting hydrological threshold events in response to climate Dr. Christoph Hinz, University of Western Australia
1735-1755
A kinematic, metamorphic and geoPhysical Properties of Ar, Kr, and Xe In chronological framework for intracratonic Higher Order Neighbour Statistics of Mar- The Uralla Magmatic Centre: preservation A Hydrogeological- landscape framework Earth's Deep Interior -eworking in the western Musgrave Block, tian North Polar Crescentic Dune Fileds )f plutonic and volcanic rocks representing providing new insights into salinity procDr. Seema Gupta, Agra College & Prof. ' central Australia: evidence for lower Andrew Wheeler, University of South an upper crustal section of some 8 km esses and management approaches. S. C. Goyal, R.B.S. College, Bichpuri, crustal extrusion? Australia Richard Flood, Macquarie University John Wilford, Geoscience Australia Agra Tom Raimondo, University of Adelaide
755-1815
Dinner (PCEC, Level 3)
0-2300
24
CONVENTION PROGRAM thursday 24 july
New Views of the Chemistry and Geology of the Crust of Mars Dr. Jeffrey Taylor, Hawaii Institute of Geophysics and Planetology, USA AIG / GSA Awards (30 mins) & POS I KR PR MORM M, i M " 1130-1315
J j : Meeting Room
r
RESOURCES (1) - Mineral Resources (Fluid Mixing and Gold Session) Chair: Dr Tim Baker 1135-1155
EARTH'S ENVIRONMENTS (3) Environmental Hazards Chair: Dr Colin Pain
GEOSCIENCE IN THE SERVICE OF GEOSCIENCE IN THE SERVICE OF SOCIETY (4) - Geohazards SOCIETY (6) - Geotourism Chair: Dr Barry Dnmmond Chair: Prof Ross Dowling
Acidic groundwater in the South west A regional landslide susceptibility An alternative model for the genesis of of Western Australia: Its distribution and programme in Tasmania gold-arsenic deposits hosted in black shale causes Colin Mazengarb, Mineral Resources and turbidite successions KEYNOTE Adam Lillicrap, Department of Tasmania Ross Large, CODES Agriculture and Food Western Australia Taking Geology to the Public: Geotourism and Geoparks Structural controls on mineralisation at the Prof. Ross Dowling, Edith Cowan Uni, Wyoming Gold Deposits, NSW: inferences The 'Lusi' Mud Eruption, Sidoarjo, East Assessment of geochemical risks of saline School of Marketing from deformation - fluid flow numerical Java - A Unique Geological Disaster acidic ground-waters in the WA wheatbelt models Dr. Mark Tingay, Uni. of Adelaide Dr. Brad Degens, Department of Water Dr. Peter Schaubs, CSIRO Exploration and Mining Lake Muir-Unicup Natural Diversity Rapid uplift and fluvial impact from the Discovery trails to early Earth — a Multiple gold events at Laverton, Eastern Recovery Catchment — groundwater Finisterre and Sarawaget Mountains, PNG traveller's guide to the east Pilbara Goldfields Superterrane, W.A. chloride/bromide ratios Dr. Martin Van Kranendonk, Geological Dr. Robert Findlay, Montagu Minerals Dr. John Miller, Centre for Exploration Margaret Smith, Curtin Uni. of Mapping Pty Ltd Survey of W A Targeting, Uni. of WA Technology
KEYNOTE The gold mineral system: do we know what we don't know? Prof. Campbell McCuaig, Centre for Exploration Targeting, Uni. of WA
Rock Tourism and the Black-footed Rock Treatment of saline acid drainage in Wallaby the Western Australian wheatbelt: field Alan Briggs, The National Trust of evaluations Australia (WA) Dr. Brad Degens, Department of Water
Tectonic/volcanic control on salinisation of Bet Bet Creek, central Victoria Dr. John Webb, LaTrobe Uni.
Volume change behaviour of unsaturated compacted clay under plane strain condition Miftahul Fauziah, Curtin Uni. of Technology
The geotourism potential investigation of E.F. Pigot S.J.; The priest who knew about Kashmar township (Northeast of Iran) Earthquakes. Morteza Taherpour Khalil Abad, Dr. David Branagan, Uni. of Sydney Islamic Azad Uni.
JS'.MeeringfeooST" RESOURCES (6) - Mineral Resources (Nickel Session) Chair: Dr Nick Haywood
KEYNOTE Advances in magmatic Ni-Cu-PGE exploration geoscience: challenging dogma and developing new ideas for an evolving search space Dr. Steve Beresford, Uni. of WA
What does the regional setting of the Voisey's Bay nickel deposit tell us about Iwhere to find similar deposits? Prof. John Myers, Curtin Uni. of Technology The Merensky Reef of the Bushveld Complex (South Africa): a X-ray computed] jtomography, microstructural, geochemical and mineralogical study Dr, Belinda Godel, Centre for Exploration Targeting, Uni. of WA The Kabanga nickel deposit, western Tanzania Dr. Wolfgang Maier, Uni. of WA
LUNCH & POS I FR P R K S I M AHO.VS r r RESOURCES (6) - Mineral Resources (Base Metals and other commodities) Chair: Mr John Lihhy 1420-1440
EARTH'S ENVIRONMENTS (3) Environmental Hazards Chair: Dr Colin Pain
GEOSCIENCE IN THE SERVICE OF SOCIETY (6) - Geotourism and Geoheritage Chair: Prof Ross Dowlins
RESOURCES (t) - Mineral Resources (Fluid Mixing and Gold Session) Chair: Mr Marcus Willson
Geology and Mineralization of the Rocklands Copper Deposits, Cloncurry District, North West Queensland Simon Beams, Terra Search Pty Ltd
The Difference Between a Rock and a Tropicana Deposit: a new gold province in A Collaborative Approach to Developing Dryland salinity and woodland biota in a a Nickel Exploration Model in the Lake Western Australia 'warming' south eastern Australia: endemic Hard Place: Using Geology to Add Value Johnston Greenstone Belt Dr. Mark Doyle, AngloGold Ashanti to the Namre-based Tourism Experience flora and fauna to the rescue! Ian Gregory, Norilsk Nickel Australia Limited A/Prof. Ian Clark, Uni. of SA Glen Bann, Australian National Uni.
Constraints on the genesis of the Nolans Bore REE-P-U-Th deposit, Northern Territory, Australia Kelvin Hussey, Arafura Resources
Infrastructure planning and contamination management Malcolm Dale, Parsons Brinckerhoff
Magmatic V-Ti-Fe mineralization at Barrambie, Western Australia Dr. Peter Collins, Curtin Uni. of Technology
Geotourism and geoparks promote education for sustainable development Patrick James, Uni. of SA
Some natural and anthropogenic sources William Blandowski's 1850s Explorations of the Geology and Landscape of of groundwater contamination in the Southeastern Australia Himalayan mountain belt Dr Doug McCann, Deakin Uni. Dr. M. Asim Yousafzai, Uni. of Peshawar
Links between orogenic-gold and mantle degassing of 40Ar plus methane Dr. Mark Kendrick, Uni.of Melbourne
Key controls on the genesis of giant magmatic sulfide systems with special reference to source controls and multistage sulfide saturation Jeffrey Foster, Uni. of Tasmania
Structural Controls and U-Pb age constraints for gold mineralisation at||Yaloginda, Murchison province. Western Australia Dr. Nick Timms, Curtin Uni. of Technology
Widgiemooltha Mine Observations of a Type 1 Komatiite Nickel Deposits and Implications for Exploration Peter Miculli, Mincor Resources NL
A genetic model for regional zonation and evolution of mineralized pegmatites from Geoscience and Food Traceability the Archaean Wodgina pegmatite district, Anita Andrew, Environmental Isotopes Pilbara Craton, Western Australia Pty. Limited Marcus Sweetapple, Curtin Uni of Technology
Geological History of the Flying Fox Nickel Deposit, Forrestania Greenstone Belt, Yilgam Craton, Western Australia: A Preliminary Assessment Jane Collins, The Uni. of WA Role of volatiles and metasomatised sub-continental lithospheric mantle in the genesis of magmatic Ni-Cu-PGE mineralisation: a case study fi-om the Valmaggia ultramafic pipe, Ivrea-Verbano Zone (NW Italy) Dr. Marco Fiorentini, Centre for Exploration Targeting, The Uni. of WA
Fluid inclusion and mineral chemical constraints on magmatic origin for metals, Cloncurry iron-oxide-Cu-Au district, NW Queensland Jaiby Ann Jacob, James Cook Uni,
1645-1715
RESOURCES (2) - Mineral Resources (Nickel Session) Chair: Prof. T. Campbell McCuaig
.afternoon m
Best Paper and ^ (Sponsored by Anglogold Ashanti Australia Limited}
CONVENTION PROGRAM 25 thursday 24 July 0900-1030
Historical Geodynamics: From Crust to Core Mantle Boundary {fYPE Theme: Deep EarSTlVom crust to core) Prof. Michael Gurnis, California Institute of Technology, USA New Views of the Chemistry and Geology of the Crust of Mars Dr. Jeffrey Taylor, Hawaii Institute of Geophysics and Planetology, USA AIG / GSA Awards (30 mins) MORNING TEA & POSTER PRESENTATIONS J7:MeetiBgRooni7 jr^: Meeting l^oom 8 Meeting l i o o i a ^ DYNAMIC EARTH (8) - The EVOLUTION OF LIFE & SOLAR DYNAMIC EARTH (11) - Riding the Proterozoic: Intercontinental vs SYSTEM (7): The Impact of Impacts Supercontinent Cycle Accretionary process Chair: Dr. Wolfgang Maier Chair: Dr Dave Evans Chair: Dr Simon Johnson
M : Meeting Keom 4 DYNAMIC EARTH (10) Breakthroughs from the Laboratory Chair: Dr Mike Mc Williams
'
0900-0945 0945-1030
1030-1100 iioS-iiio
jriOtiVieetingftooinlO
1130-1315
GEOSCIENCE IN THE SERVICE OF SOCIETY (5) - Geoscience Education Chair: Mr Greg McNamara
Advances in SHRIMP zircon U-Pb geochronology and oxygen isotopic analysis Dr. Ian Williams, The Australian National University
New mapping from potential fields data 1135-1155 in the Air, Damagaram, and South Maradi regions of Niger, West Africa KEYNOTE Mr. Jurriaan Feijth, Fugro Airborne KEYNOTE KEYNOTE The impact of impacts: impact as a Surveys Formation of a Supercontinent, Framework Fighting the plight: eartli science on the geological process and significance in Paleoproterozoic terrane boundaries in the of the Super-Resoui ce: The East African 1155-1215 march in Western Australia economic geology unexposed Northern Gawler Craton, Maria Orogen and the Amalgamation of Arabia Dr. James Ross, Earth Science Western Dr. Peter Haines, Geological Survey of Titanite as a tracer of crustal evolution Region: new insights from a geophysical Dr. Alan Collins, University of Adelaide Australia Western Australia Dr. Craig Storey, University of Bristol perspective Dr. Graham Baines, CMXUC Univesity of Adelaide The Effects of Crystal-Plastic 1215-1235 The accretion of north and south The geophysical signatures of Australia's Tertiary Geoscience Education in Deformation on the U, Th, Pb, REE and Ti A Gawler Orocline?: YarlbrindaGondwana: evidence from U-Pb ages meteorite impact structures Australia: WTiat future? Geochemistry of Zircon Oolabinnia Shear Zone connections Dr. Phil Hawke, University of Western and Hf-isotopic compositions of detrital Dr. Trevor Powell, Australian Dr. Nick Timms, Curtin University of John Stewart, Monash University zircons from the Damara Orogen, Namibia Australia Geoscience Council Technologv Prof. David Foster. University of Florida 1235-1255 In situ measurement of sulphur isotope A newly discovered meteorite impact Gauging reasons for enrolment in an entry Metamorphism of the Mount Woods Evolution of the Gawler-Adelie Craton: ratios: new developments and results using crater, Opthalmia Range, Western level university geology course: ResuUs of Domain, Gawler Craton Links with Antarctica, northern Australia the SHRIMP Australia student surveys from 2002-2007 Dr. Caroline Forbes, University of and basement of the Trans-Hudson Orogen Dr. Richard Armstrong, Australian Dr. Arthur Hickman, Geological Survey Dr. Karen Barovich, University of Adelaide Justin Payne, University of Adelaide National University of Western Australia Adelaide Dynamic permeability in fine-grained Granulites in the Northern Gawler ultramylonites - implications for fluid flow Craton: the high temperature record of in mid-crustal shear zones Mesoproterozoic crustal thickening Dr. Florian Fusseis, SEGS - UWA Kathryn Cutts, University of Adelaide mtMt^rn^Bmml DYNAMIC EARTH (8) - The Proterozoic: Intercontinental vs Accretionary process
DYNAMIC EARTH (10) Breakthroughs from the Laboratory Chair: Dr Mike Mc Williams
Sedimentary and Petrologic Evidence of a Tookoonooka Impact Event Ejecta Layer, Australia Katherine Bron, University of Adelaide LUNCH & POSTER PRESENTATIONS lOr^MeefiagKooma EVOLUTION OF LIFE & SOLAR SYSTEM (7): The Impact of Impacts Chair: Dr Peter Haines
Confirmed LL chondritic meteorite within An exploratory laboratory study of the role Early Mesoproterozoic crustal anatexis in the melt sheet of the giant Morokweng of water in seismic-wave attenuation the Gawler Craton, South Australia impact crater, South Africa Prof. Ian Jackson, Australian National Justin Payne, University of Adelaide Dr. Wolfgang Maier, University of University Western Australia Towards laboratory study of dislocationrelated seismic-wave attenuation in olivine Robert Farla, Australian National University
Textural controls on c. 1675, 1600, and 510 Ma monazite around Broken Hill Dr. Paul Evins, Geological Survey of Western Australia
Deformation, Chemistry and Hydrogen in Superimposed Neoarchean and Olivine: Consequences for Mantle Flow Paleoproterozoic tectonometamorphic Characterisation and Seismic Anisotropy events in the Terre Adelie Craton (East of the Lithosphere Antarctica) A/Prof. Steve Reddy, Curtin University Guillaume Duclaux, CSIRO Exploration of Technology and Mining
Timing of the Lawn Hill Impact Crater and Relationship to the Century Zn-Pb Deposit, Northwest Queensland Jess Salisbury, Monash University Direct field evidence for Archaean and early Proterozoic Eros-scale asteroid impacts and major geodynamic consequences, Kaapvaal and Pilbara Cratons Dr. Andrew Glikson, Australian National University Hydrothermal systems associated wiht meteorite impacts Dr. Franco Piranjo, Geological Survey of Western Australia
Were there two or three Proterozoic supercontinents? Quantitative tests of craton connections in Geon 24 Dr. Aleksey Smirnov, Michigan Technological University
Geological Society of America's Public Policy Programs Dr. John Hess, Geological Society of America
1255-1315
1315-1415
m.M^gkrnm^
1415-1600
DYNAMIC EARTH (11) - Riding the Supercontinent Cycle Chair: Dr Alan Collins
GEOSCIENCE IN THE SERVICE OF SOCIETY (5) - Geoscience Education Chair: Mr Greg McNamara
Education & Outreach - An outline of 1420-1440 the efforts of the Geological Society of America Gary Lewis, Geological Society of Crustal budgets, shifting continents and America the search for Proterozoic ores Fact-ites, Quizzicles and EarthCaching: 1440-1500 Prof. David Giles, The University of The Geological Society of Australia Adelaide Education and Outreach Initiatives. Where to from here? Greg McNamara, Geological Society of Australia 1500-1520 The Teacher Earth Science Education Programme [TESEP] and Geoscience Supercontinents, supermountains and the Pathways: A national scheme to assist rise of atmospheric oxygen teachers and help students discover Earth Prof. Ian Campbell, The Australian Science and associated career paths National University Greg McNamara, Geological Society of Australia & Len Altman, Marden Senior College Living Geodiversity' - simplified geology maps and linked eco-geo field trips for school and community education Glen Bann, Australian National University
Tectonics, plumes and supercontinents: The energy link Dr. Graham Begg, Minerals Targeting International PL
1520-1540
1540-1600
New Perspective on the Lunar Cataclysm from Crater Density Populations Dr. Marc Norman, Australian National University
THE DYNAMIC EARTH: Wrap-Up discussion
Best Paper and Poster Awards • " /
'
^ ' •
1
1
1645-1715
26 SPEAKER ABSTRACT INDEX by t h e m e / by d a y
Abstracts are listed alphabetically by first presenting author. The index below lists abstracts by convention theme and day. THEME: Dynamic Earth: From Crust to Core Monday 21 July ANAND ASPANDIAR BAROVICH
FIRSTNAME Ravi Mehrooz Karin
BLEVIN CLARK CZARNOTA DAVIES DOWNES DUTCH
Jane Chris Karol Geoff Peter Rian
FLAMENT FORSTER ERASER
Nicolas Mamie Geoffrey
GILKES GOSCOMBE GOZZARD GRAY
Bob Ben Bob David
HAIG HILL
David Steve
HOU
Baohong
HOWARD
Katherine
HZUKA IVANIC
Tsuyoshi Tim
KEEP KEMP
Myra Tony
LANGFORD LISTER MCCARTAIN MUHLING
Richard Gordon Eujay Janet
MYERS NUTMAN
John Allen
PILLANS RIGANTI
Brad Angela
SURNAME
ROMANO
Sandra
SANDIFORD SCHELLART
Mike Wouter
SELWAY VAN KRANENDONK
Kate Martin
Session PAPER TITLE C8 How psoliths form C8 Recognition and geological significance of Cenozoic paleosols in the regolith profile C6 Depositional age and provenance of the Palaeoproterozoic Hutchison Group, southern Gawler Craton, South Australia B6 Geodynamics and Basin Evolution A6 U-Pb isotopic age constraints on event timing in the Southern Granulite Terrane, India C7 An integrated tectonic framework of the Eastern Goldfields Superterrane A7 The Early Mantle: Depletion, Plates, Resurfacing Episodes and Isotopes C8 Secondary minerals from the Braeside lead field, Pilbara, Western Australia. C6 Tectonothermal evolution of the Kimban Orogeny, Southern Gawler Craton; evidence for extrusional tectonics during the development of a transpressional orogen A7 Surface area of emerged land and depth of mid-oceanic ridges in the Archean A6 Orogen-scale tectonic shuffle zones. C6 The Kararan Orogeny - a link between the Proterozoic North Australian and South Australian cratons? C8 The dregs of weathering: regolith mineralogy and chemistry C7 Metamorphic evolution of the Eastern Goldfields Superterrane B8 Understanding the landscapes of the Perth Region B8 The Top Down paradigm - do plants control groundwater and weathering in semi-arid Australia? B6 Timor stratigraphy reconstructed: 155 Ma to present B8 A Regolith and Landscape Evolution Framework for Mineral Exploration Under Cover in the Northern Flinders Ranges - Frome Embayment, South Australia B8 New Insights into Landscape Evolution of the Eucla Basin and Palaeochannels, Southern Australia C6 U-Pb, Nd and Hf isotopic constraints on basin development and deformation in the Western Gawler Craton B7 U-Pb dating of monazites from Mt. Narryer metasedimentary rocks C7 Large volumes of mafic magmatism affecting Meso-Neoarchean crust, Murchison Domain, Youanmi Terrane, Yilgam Craton, Western Australia B6 Timor stratigraphy deconstructed: Neogene and ongoing collision A7 Continental materials on Earth by 4.5 Ga from Hf-Pb isotope systematics of the Jack Hills zircons. Western Australia A8 Visualising landscape evolution with SRTM data: regolith landform mapping in the Tanami A6 The accretion model for orogenesis. B6 Timor stratigraphy reconstructed: Permian to Middle Jurassic B7 Dating high-grade metamorphic events in the Narryer Terrane by U-Pb SHRIMP analysis of monazite and zircon B7 Archean plate tectonic processes in southwest Greenland B7 Ophiolite in the Eoarchaean (>3700 Ma) Isua supracmstal belt (Greenland): A 41 year-old debate A8 Geochronology of regolith-landform evolution in Australia: a brief review C7 Neoarchean siliciclastic sedimentary successions of the central Yilgam: an equivalent to the Eastern Goldfields Superterrane late-stage basins? C7 Granite-greenstone associations of the Yamama - Irwin Hill region, Burtville Terrane, Yilgam Craton, Australia A8 The tihing continent and other geomorphic signals of mantle flow beneath Australia A6 A parametric study of overriding plate shortening and extension above subduction zones: Explaining the formation of the Andes C6 Cmstal to lithospheric-scale stmcture of the Capricom Orogen from magnetotellurics A7 Formation of Archean continental cmst from an oceanic plateau in a non-subduction setting: the east Pilbara example
Page 42 45 50 58 66 76 79 84 86 100 103 104 110 116 117 117 126 135 138 141 143 144 151 152 159 166 172 179 183 190 200 210 214 218 220 224 246
THEME: Dynamic Earth: From Crust to Core Tuesday 22 July SURNAME BACKE BELOUSOVA BUTTNER COLLINS DHUIME FINDLAY FISHWICK FOSTER GIBSON
FIRSTNAME PAPER TITLE Guillaume Basement faults control over salt-driven tectonics in the Central Flinders Ranges, South Australia. Elena TerraneChron" approach to the cmstal evolution studies and implications for continental growth Steffen The Sierras Pampeanas - Puna basin connection: Ordovician cmstal thinning and back-arc basin formation at the SW Gondwana margin William The Phanerozoic: Reconciling modem plate tectonics with ancient orogenic systems and cmstal growth Bmno Integrated isotope and trace element analyses of detrital minerals from the Frankland River (SW Australia) Robert Age and provenance of the Owen Stanley Metamorphic Complex (East Papuan Composite Terrane) in Morobe Province, Papua New Guinea Stewart The Shear Wavespeed Stmcture of the Australian Lithosphere: Is it Compatible with Physically Based Models? David The southwestem Laurentian lithosphere in the northem Rockies, USA: cmstal provinces, plutonic imaging, and seismic stmcture George Proterozoic cmstal architecture and evolution in the Mount Isa region: new insights from seismic reflection profiling
Australian Earth Sciences Convention 2008
Session D6
Page 46
D7
54
D9
61
E9
71
D7
83
E9
97
E7
99
F7
103
E6
109
SPEAKER ABSTRACT INDEX 27 by theme / by day
THEME: Dynamic Earth: From Crust to Core - Continued Tuesday 22 July SURNAME GOLEBY HEALY HENDERSON HOCKING HONGTAO ICKERT KEEP KEMP KENNETT KIRBY KLOOTWIJK KORSCH KOVAC LAMBECK MATHEWS MURPHY MUSGRAVE NEUMANN O'REILLY RAWLINSON REY RICHARDSON RUXTON SOUTHGATE WADE WADE WHITE
FIRSTNAME PAPER TITLE Session Bruce Characteristics of the Australian Crust from Seismic Reflection Profiling E7 David Anisotropy of Lithosphere Strength F7 Bob Accretion of a Late Ordovician island arc terrane into the northern Tasmanides and its E9 implications for orogenesis. Roger Vines 1 revisited: Neoproterozoic successions in Western Australia D6 Zhu Tectonic Controls on the Sequence Stratigraphic Architecture in a Non-marine Rift-basin D6 Setting: An Example from the Tertiary Bohai Bay, East China. Ryan In situ U-Pb, O, and Hf isotope measurements of I- and S-type granites from the Berridale and D9 Kosciuszko Batholiths Myra Does the Capricorn Orogen control seismicity in the Carnarvon Basin? D6 Tony Isotopic evidence for continental growth during accretionary orogenesis in the Tasmanides, D9 eastern Australia Brian Lithospheric Edges and Sutures E7 Jon Elastic thickness of Precambrian cratons - a global study D7 Chris Tectonic extrusion of the Thomson Orogen: Australia-Asia equivalent of India-Asia F9 deformation Russell Crustal architecture of Central Victoria: results from the 2006 deep cmstal reflection seismic F7 survey Peter Geological structure of the Kumbmf volcanic arc (Bismarck Range, PNG Highlands) F9 Alexis An integrated sedimentological, geochemical and geochronological analysis of Georgetown: E6 Constraints on basin development and paleo reconstructions. Emma Palaeozoic granites in central Queensland: a transect across the Thomson - New England E9 Orogen boundary; implications of the role of crustal composition for granite formation Melissa Provenance of Ophiolitic Sand: Comparison of Ancient and Modem Sand D9 Robert Potential field models of the Bancannia Trough - Koonenberry Belt system, NSW: tectonics F9 of a rifted arc. Narelle New geochronological constraints on sedimentation in the Georgetown Inlier: Correlations E6 with the Mount Isa Inlier. Suzanne Archean Lithospheric mantle: formation, composition and today's refertilised remains. D7 Nicholas WOMBAT: An evolving seismic array experiment in Australia E7 Patrice From the strengthening, emergence and erosion of continents in the Neoarchaean, to the F7 coupling of Earth's geochemical reservoirs. Shane Strength of high-geotherm lithosphere: Weak, strong, or failing? F7 Bryan Mirror Images in East and West Papua F9 Peter Using time-constrained facies belts and sequence models to correlate the Western and Eastern E6 successions of the Mt Isa Inlier: implications for fluid migration. Ben A record of late Palaeoproterozoic metamorphism and reworking in the Cadney E6 Metamorphics, Strangways Metamorphic Complex, central Australia. Ben Provenance of metasedimentary rocks from the Entia Dome, eastern Arunta Region, central D6 Australia: a combined U-Pb SHRIMP, LA-ICPMS and Sm-Nd isotope study. Lloyd Attenuation of high-strain zones in the Wyangala Granite, Eastern Lachlan Fold Belt, NSW, F9 Australia.
Page 114 130 132 136 138 143 151 152 153 154 154 155 156 157 170 181 182 186 193 207 209 210 215 232 248 248 252
THEME: Dynamic Earth: From Crust to Core Wednesday 23 July SURNAME
EVINS
FIRSTNAME PAPER TITLE Nick Mantle melting Karin Nd isotopes and their utility in crustal evolution studies in Proterozoic Australia Miriam Extension in lower cmstal granulite facies mafic orthogneisses of the Biranup Complex (Albany-Fraser Orogen), Bremer Bay, Westem Australia Vickie Early History of Planet Earth from Combined 142- I43Nd and 176Hf Isotopic Signatures Pete Evidence for a Mesoproterozoic hotspot track in eastem and central Australia Pete Proterozoic accretionary processes of Australia and comparisons with Laurentia. Rachael Formation of the eclogite hosting 2.0 Ga Usagaran Orogenic belt, Tanzania Fabio Antonio Deep subduction dynamics and its expression in plate motions Neil Comparing isotopic and trace element geochemistry of the St Peter Suite with later gabbroic intmsions Paul Little time for a lot of LIP: Relative timing of magmatism and deformation during the c. 1070 Ma Giles Event in the Musgrave Complex of Westem Australia Lena The extent and distribution of the Kalkarindji Large Igneous Province.
FIORENTINI
Marco
ARNDT BAROVICH BARQUERO-MOLINA BENNETT BETTS BETTS BRICK CAPITANIO CHALMERS EVINS
FLOOD FORBES FROST GOYAL GRIFFIN GUPTA HAINES HAWKESWORTH HEINE HERMANN
Three-dimensional morphology of magmatic sulphides sheds light on ore formation, mantle melting and segregation of the Earth's core The Uralla Magmatic Centre: preservation of plutonic and volcanic rocks representing an upper cmstal section of some 8 km Caroline Reinterpretation of high-temperature metamorphism within a continental back-arc setting for the Broken Hill Block, NSW Edmund Controls on syndepositional fracture patterns, Devonian reef complexes. Canning Basin, Westem Australia S.C. Elastic Behaviour of Earth's Lower Mantle Solids Under High Compression William The Proterozoic: Hiding Archean in the basement Seema 'Physical Properties of Ar, Kr, and Xe In Earth's Deep Interior' Co-presenter: S. C. Goyal Peter Provenance of Paleozoic sandstone in the Canning Basin using SHRIMP U-Pb dating of detrital zircons Chris Large Igneous Provinces, Mantle Plumes and Cmst Generation Christian Integrating deep Earth dynamics in paleogeographic reconstmctions of Australia Joerg Experimental constraints on the slab component of arc magmas Richard
Session G9 G7 17
Page 44 51 52
G9 H9 G7 H7 G6 19
No. Ab. 56 55 59 63 64
19
91
H9
90
G9 19
100
G7
101
G3
105
16 H7 16
117 122 124
H3
126
H9 G6 G9
130 131 133
Australian Earth Sciences Convention 2008
28 SPEAKER ABSTRACT INDEX by theme / by day
THEME: Dynamic Earth: From Crust to Core - continued Wednesday 23 July SURNAME HOCKING HOWARD JOHNSON
FIRSTNAME Roger Heather Simon
KROMKHUN
Kamonpom
LI LI
Zheng-Xiang Zheng-Xiang
MAIER
Wolfgang
MASLEN
Ercin
MASON MULLER NICOLL NICOLL O'NEILL PLAYFORD RAIMONDO
Wendy Dietmar Robert S. Robert S. Craig Phillip Tom
REGENAUER-LIEB REY SCHELLART
Klaus Patrice Wouter
SCHELLART
Wouter
SCHWARZ SPAGGIARI
Ailsa Catherine
THOMPSON TYLER
Neil Ian
VAN KRANENDONK
Martin
Session PAPER TITLE G3 Cyclicity in Late Devonian conglomerates, Lennard Shelf, Canning Basin, W.A. 19 Geochemical and Nd isotopic signatures of mafic dykes in the western Musgrave Complex G7 The Glenburgh Terrane: a record of subduction and collision in the Paleoproterozoic Capricorn Orogen of Western Australia H7 Mineralogy of Mesoproterozoic high heat producing granite and mafic dyke from Mount Painter Province 19 Plate vs. plume: clues from Neoproterozoic geodynamic record H6 How to recognise flat-slab subduction and foundering: an example in orogenic, magmatic and basin records of Mesozoic South China H9 Systematic PGE depletion in early- to mid- Archean komatiites from the Pilbara and Kaapvaal cratons G3 The significance and origin of the biomarker crocetane in Devonian source rocks and crude oils (Western Canada Sedimentary Basin and Canning Basin, WA) 16 Thermochemical controls on the subduction of oceanic plateaus G6 What drives major episodic reorganisations of the plate-mantle system? H3 The Permian Conodont biostratigraphy of Western Australia - an update H3 The Cambro-Ordovician, the Centralian Superbasin (Part 2) and trans-Gondwanan Seaways. H6 The emergence of steady-state plate tectonics in dynamic mantle models G3 Devonian reef complexes of the Canning Basin: 50 years of research 17 A kinematic, metamorphic and geochronological framework for intracratonic reworking in the western Musgrave Block, central Australia: evidence for lower crustal extrusion? H6 Multi-scale Earth System Dynamics Coupling Mechanics with Chemistry G6 On the dynamics of active continental margins H6 Subduction zone dynamics on Earth: Insight from geodynamic models, kinematic calculations and observations 16 Discovery of a fossil slab in the lower mantle below the Tasman Sea using plate reconstructions and mantle tomography 17 The crustal evolution of the Musgrave Province 17 The c. 1680 Ma Dalyup Gneiss of the Albany-Eraser Orogen, Western Australia: What is it, and where did it come from? H3 Canning Basin oil and gas potential 17 Assembling the western North Australian Craton: Linking the King Leopold, Halls Creek, Granites-Tanami and Amnta orogens 16 Early Archean tectonics and the start of modem subduction
Page 136 140 148 156 163 163 168 170 170 181 187 188 192 201 206 208 209 221 220 221 232 240 243 245
THEME: Dynamic Earth: From Crust to Core Thursday 24 July SURNAME ARMSTRONG BAINES BEGG CAMPBELL COLLINS CUTTS DUCLAUX EVINS FARLA FEIJTH FORBES FOSTER FUSSEIS GILES JACKSON PAYNE PAYNE REDDY SMIRNOV STEWART STOREY TIMMS WILLIAMS
Session FIRSTNAME PAPER TITLE J6 In situ measurement of sulphur isotope ratios: new developments and results using the Richard SHRIMP II. J7 Paleoproterozoic terrane boundaries in the unexposed Northern Gawler Craton, Maria Region: Graham new insights from a geophysical perspective K9 Tectonics, plumes and supercontinents: The energy link Graham K9 Supercontinents, supermountains and the rise of atmospheric oxygen Ian J9 Formation of a Supercontinent, Framework of the Super-Resource: The East African Orogen Alan S and the Amalgamation of Arabia J7 Granulites in the Northern Gawler Craton: the high temperature record of Mesoproterozoic Kathryn crustal thickening. K7 Superimposed Neoarchean and Paleoproterozoic tectonometamorphic events in the Terre Guillaume Adelie Craton (East Antarctica) K7 Textural controls on c. 1675, 1600, and 510 Ma monazite around Broken Hill Paul K6 Towards laboratory study of dislocation-related seismic-wave attenuation in olivine Robert J7 Jurriaan New mapping from potential fields data in the Air, Damagaram, and South Maradi regions of Niger, West Africa J7 Metamorphism of the Mount Woods Domain, Gawler Craton Caroline J9 The accretion of north and south Gondwana: evidence from U-Pb ages and Hf-isotopic David compositions of detrital zircons from the Damara Orogen, Namibia J6 Dynamic permeability in fine-grained ultramylonites - implications for fluid flow in midElorian crustal shear zones K9 Crustal budgets, shifting continents and the search for Proterozoic ores David K6 An exploratory laboratory study of the role of water in seismic-wave attenuation Ian K7 Early Mesoproterozoic crustal anatexis in the Gawler Craton, South Australia. Justin J9 Evolution of the Gawler-Adelie Craton: Links with Antarctica, northern Australia and Justin basement of the Trans-Hudson Orogen K6 Deformation, Chemistry and Hydrogen in Olivine: Consequences for Mantle Flow Steven Characterisation and Seismic Anisotropy of the Lithosphere J9 Were there two or three Proterozoic supercontinents? Quantitative tests of craton connections Aleksey in Geon 24 J7 A Gawler Orocline?: Yarlbrinda-Oolabinnia Shear Zone connections. John J6 Titanite as a tracer of crustal evolution Craig J6 The Effects of Crystal-Plastic Deformation on the U, Th, Pb, REE and Ti Geochemistry of Nick Zircon J6 Advances in SHRIMP zircon U-Pb geochronology and oxygen isotopic analysis Ian
Australian Earth Sciences Convention 2008
Page 44 47 53 62 70 75 86 91 94 95 101 103 106 110 144 196 197 207 229 233 234 241 254
SPEAKER ABSTRACT INDEX 29 by theme / by day
THEME: Earth's Environments: Past, Present and Future Monday 21 July SURNAME
ARCULUS CHEN COLLINS DADD EXON EXON FANNING
GALLAGHER GLENN GLIKSON GOLDING GOSTIN HAIG HASHIMOTO HENDERSON JAHNERT JORGENSEN MCLAREN OPDYKE PERYT ROLFE WEBSTER WEBSTER WILLE WUST
FIRSTNAME PAPER TITLE Session Page Richard Australia and the Integrated Ocean Drilling Program (lODP) A9 43 Zhong Qiang Episodic anoxic events recorded in the Permian-Triassic transition of the Meishan section, CIO 65 South China: Sedimentary characterization and faunal response Lindsay Quaternary evolution of Scott Reef, Northwest Shelf, Australia A9 71 Kelsie The University of the Sea and the benefits to learning of active participation in a research A9 76 cruise. Neville Geology of the submarine Mellish Rise off Northeast Australia C9 92 Neville Coring the Cenozoic Sequences of the Northern Carnarvon Basin of Australia to Answer C9 92 Gobal Eustatic Questions C. Mark Age constraints on the Sturtian Glaciation in Adelaide Geoscyncline, South Australia and the BIO 93 Pocatelo Formation of Idaho, USA indicate that there was no single Sturtian Snowball. Late Cretaceous dysoxia in a southern high latitude deltaic to outer shelf succession, the Stephen C9 107 Otway Basin, southeast Australia Kriton C. Mass wasting along the East Australian continental Slope C9 111 Andrew Milestones in the evolution of the atmosphere with reference to climate change BIO 112 Ancient analogues for C02 sequestration in coal measures, Gunnedah and Bowen Basins, AlO 113 Suzanne Australia Ice-rafting in the Mid-Ediacaran (-580 Ma) Adelaide Geosyncline and Officer Basin, South BIO 116 Victor Australia. Foraminiferal tracers for climate and water-quality changes in Permian interior seas in AlO 125 David northeastern Gondwana Riko Capel and Faust basins — geoscientific assessment of an offshore frontier region C9 128 Bob New perspectives on the palaeoecology of Cambrian phosphatic brachiopods AlO NoAb. Facies patterns in carbonates of the Aptian Stage in Pamafba Basin, Brazil and insights from Ricardo CIO 145 possible modem analogues. Diane Carbonate aeolianite systems within the Naturaliste-Leeuwin region of southwest Western A9 150 Australia: correlation with the Pleistocene-Holocene chronology of the Perth region Sandra Age and stratigraphic constraints on the evolution of mega-lake Bungunnia: Insights into Plio- AlO 174 Pleistocene climate change in southern Australia Brad Two New lODP Paleoceanographic Drilling Opportunities in the Timor Sea: Late Quaternary B9 193 Paleoceanography and Tracking Sea Level change from the Late Miocene Tadeusz Chemical composition of seawater in Neoproterozoic and Paleozoic: a contribution based on BIO 197 study of fluid inclusions in halite from Australia. Matthew Palaeoclimate driven eustatic signature of the Middle Devonian anoxic Pumillo Event from BIO 213 reef complexes of the Emanuel Range, Lennard Shelf Jody Sediment flux and composition changes in canyons on a carbonate-siliciclastic margin: B9 251 evidence from turbidite deposits along the Great Barrier Reef margin. Jody Drowned reefs in the Great Barrier Reef and Hawaii: a new era in lODP coral reef drilling B9 251 Evidence for a massive H2S release to surface waters at the Precambrian Cambrian (PC-C) Martin CIO 253 boundary from Mo isotopes Raphael Multiphase palaeochannel development on the Great Barrier Reef Shelf, Australia B9 258
THEME: Earth's Environments: Past, Present and Future Tuesday 22 July SURNAME
ARCULUS BINNIE CANN
DANYUSHEVSKY DUTTON GALLAGHER SMITH WILSON WUST
FIRSTNAME PAPER TITLE Session Page Richard Ritter Volcano, West Bismarck Arc: tsunamigenic collapse and peridotite xenolith locality DIO 43 Mary-Anne Benthic Foraminifera assemblages in the northern Spencer Gulf, South Australia - further FIO 57 evidence for Holocene sea-level changes. John Distribution and ecology of benthic foraminifera in the Coorong Lagoon and adjacent waters ElO 62 South Australia; to aid palaeo- reconstructions. Leonid V. Tectonics and volcanism associated with the propagation of backarc spreading and associated DIO 78 riftmg of an island arc: An example from the southeast margin of the North Fiji Basin Sea level reconstructions from fossil coral reefs along the Cape Range coast, Western Andrea FIO 87 Australia Stephen Cenozoic biogeographic evidence for West Pacific Warm Pool formation and the initiation of ElO 106 the Kuroshio and Leeuwin Current Sian Sequence Stratigraphy and Seismic Facies of the Eucla Basin, Great Australian Bight, South DIO 230 Australia. Moyra Cenozoic carbonate response to climatic change due to a tectonic-induced latitudinal shift FIO 256 MWP-1A and its implication for the moisture regime change over Borneo - evidence from Raphael FIO 259 peat archives
THEME: Earth's Environments: Past, Present and Future Wednesday 23 July SURNAME
CLARKE GIBSON GIBSON HINZ LAWRIE PAIN
FIRSTNAME PAPER TITLE Jonathan Architecture of an Entrenched Valley Fill, Murray River David Variability in landscape evolution rates, and the preservation of regolith David Using AEM imagery to map palaeo strand lines in the Loxton Parilla Sands, Murray River corridor, Victoria Christoph Predicting hydrological threshold events in response to climate Ken Recent advances the application of hydrogeophysics groundwater and insalinity mapping and management and regolith geoscience for Colin Input of geomorphic and regolith mapping to the Interim Biogeographic Regionalisation for Australia (IBRA)
Session Page HIO 68 110 109 HIO 108 110 135 HIO 160 110 194
Australian Earth Sciences Cdiivention 2008
30 SPEAKER ABSTRACT INDEX by theme I b f day
THEME: Earth's Environments: Past, Present and Future - continued Wednesday 23 July SURNAME TAN WILFORD WONG
FIRSTNAME PAPER TITLE Customised products derived using airborne EM and hydrogeological data to assist m land use Kok Piang management along the Murray River in New South Wales and Victoria, Australia A Hydrogeological- landscape framework providing new insights into salinity processes and John management approaches. Vanessa Integrating remote-sensing with airborne electromagnetics for vegetation and crop health along the River Murray Corridor
Session HIO 110
no
Page 238 253 257
THEME: Earth's Environments: Past, Present and Future Thursday 24 July SURNAME ANDREW ASIM YOUSAFZAl BANN DALE DEGENS DEGENS LILLICRAP SMITH WEBB
Session FIRSTNAME PAPER TITLE K2 Anita S Geoscience and Food Traceability K2 M. Some natural and anthropogenic sources of groundwater contamination in the Himalayan mountain beh. j r. j K2 Glen Dryland salinity and woodland biota in a 'warming' south eastern Australia: endemic flora and fauna to the rescue! K2 Malcolm Infrastructure planning and contamination management J2 Brad Assessment of geochemical risks of saline acidic ground-waters in the WA wheatbeh J2 Brad Treatment of saline acid drainage in the Western Australian wheatbelt: field evaluations J2 Adam Acidic groundwater in the South west of Western Australia: Its distribution and causes. J2 Margaret Lake Muir-Unicup Natural Diversity Recovery Catchment — groundwater chloride/bromide ratios J2 John Tectonic/volcanic control on salinisation of Bet Bet Creek, central Victoria
Page 43 45 49 77 80 81 164 230 250
THEME: Evolution of Life and the Solar System Monday 21 July SURNAME AWRAMIK COFFEY GOLDING GREY NOFFKE PHILIPPOT RUNNEGAR STOAKES SUGITANI VAN KRANENDONK WEBB
FIRSTNAME PAPER TITLE Stanley The Quest for Perfection - Biogenicity and the Early Fossil Record Jessica The Palaeontology and Palaeoecology of the 2.7Ga Tumbiana Formation, Pilbara Craton, Western Australia. Suzanne Isotopic evidence for redox heterogeneity in the late Archean and early Paleoproterozoic Hamersley Basin, Western Australia Kathleen Morphological complexity and diversity in the c.3.40 Ga Strelley Pool Chert, Pilbara Craton — evidence for a biogenic origin Nora Microbially induced sedimentary structures - signs of life in Archean to modem sandy marine settings Pascal Early Archaean Microorganisms Preferred Elemental Sulfur, Not Sulfate Bruce A reassessment of the evidence for sulphur-based microbial metabolic activity in the early Archean at North Pole, Western Australia. Cris The ~3.43Ga Strelley Pool sandstone as an environment for early life Kenichiro Highly elaborate putative microfossils from >2.97 Ga chert, Pilbara Craton: indications of cell division? Martin Environments of life at 3.5-3.3 Ga; evidence from the East Pilbara Terrane, Western Australia. Gregory Distinguishing microbial carbonates using in situ LA-ICP-MS vital trace element geochemistry: implications for biogenicity
Session A2 A2
Page 45 69
C2
114
B2
120
A2
188
C2 C2
199 215
B2 A2
234 235
B2 C2
246 249
THEME: Evolution of Life and the Solar System Tuesday 22 July SURNAME HICKMAN KIYOKAWA LEPOT NEDACHI NEDACHI OHMOTO OHMOTO PHILIPPOT PHILIPPOT VAN KRANENDONK VAN ZUILEN YAMAGUCHI
Session FIRSTNAME PAPER TITLE D2 Arthur An overview of four international geoscientific drilling projects, Pilbara Craton, Western Australia, 2003 -2007 E2 Shoichi 3.2 Ga island arc oceanic sedimentary sequence: Preliminary result of the Dixon IslandCleaverville drilling (DXCL-dri) Project. F2 Kevin Nano-aragonite associated with organic globules supports a biogenic origin of 2.7 Gyr old stomatolites D2 Munetomo Bio-activity in the 3.46 Ga ferruginous Marble Bar Chert, Pilbara, Western Australia E2 Munetomo Shallower Submarine Ecosystem at 2.7-2.8 Ga, Pilbara, Western Australia D2 Hiroshi Geochemical evidence for the development of a fully-oxygenated atmosphere-oceans and D2 modem-style ecosystems by -3.5 Ga F2 Hiroshi Possible generation of MIF-S during hydrothermal alteration of organic rich sediments Pascal Multiple Sulfur and Carbon isotopic chemostratigraphy of the 2.73 Ga carbonated Tumbiana F2 Formation, new insights for the Fortescue excursion. E2 Pascal The Pilbara Drilling Project: Results and Perspectives Martin A volcanic caldera habitat for Earth's oldest stromatolites (c. 3.5 Ga) from the North Pole E2 Dome, Western Australia. Mark Photosynthesis in a 3.5 Ga old shallow marine depositional environment; clues from carbon E2 and iron isotope systematics. ,, i, Kosei Geochemical evidence for oxygenated oceans 3.46 Ga ago: REE geochemistry of the Marble Bar Chert recovered by the Archean Biosphere Drilling Project (ABDP)
Australian Earth Sciences Convention 2008
Page 134 154 162 184 185 191 191 199 199 244 247 259
SPEAKER ABSTRACT INDEX 31 by theme / by day
THEME: Evolution of Life and the Solar System Wednesday 23 July SURNAME ALLTON AMELIN BARGE BERMINGHAM CAPRARELLI CHEN CLARKE DUTKIEWICZ GRICE IRELAND LAN METCALFE NABBEFELD
NEMCHIN O'NEILL PRENTICE SALMERON TAYLOR WEBB WHEELER WILLIFORD
FIRSTNAME PAPER TITLE Session Judith Dust to Planets - what have we learned from Genesis and Stardust Samples? G8 Yuri Dating Fractionation of Refractory and Volatile Elements in the Protoplanetary Disk G8 Mineral Precipitation in Porous Media: Laboratory Diffusion Experiments as Analogues for Laura 18 Concretion Formation in Utah and on Mars Katherine A New Type of Basaltic Eucrite: Clues to Early Differentiation of Igneous Asteroids H8 Layered units at the Martian dichotomy and their geological significance Graziella 18 Restoration of marine ecosystems following the Permian-Triassic mass extinction in Zhong H2 Gondwanan interior sea Jonathan The Dalhousie Mound Spring Complex as a guide to Martian Landforms and Processes 18 Adriana Palaeoproterozoic hydrocarbons associated with uranium and gold deposits G2 Perylene: a molecular marker for lignin degradation and a signal for the rise of vascular plants Kliti G2 Chronology of the Early Solar System through Short-lived and Long-lived Chronometers Trevor H8 Discovery of Paleodictyon in brackish water environment from the Permian of the Carnarvon Zhongwu H2 Basin, Western Australia. Ian Position of the end-Permian mass extinction level and Permian Triassic boundary in Australia H2 Global significance of stable carbon, sulfur and hydrogen isotope signals together with Birgit H2 higher plant derived components of sedimentary organic material from the Permian/Triassic boundary Alexander Early evolution of Earth and Moon H8 Craig A spectrum of Hadean geodynamics from diamond stability constraints H8 Formation of the Inner Solar System: new insights revealed by spacecraft data. Andrew G8 The formation and early evolution of the solar system Raquel G8 Extremes of Igneous Fractionation in the Moon Jeffrey H8 Gregory Trace element geochemistry of Neoproterozoic stromatolites: a tool for interpreting G2 accretionary processes Andrew Higher Order Neighbour Statistics of Martian North Polar Crescentic Dune Fileds 18 Molecular and isotopic evidence for a microbial response to the Triassic-Jurassic mass Kenneth H2 extinction
Page 41 42 50 55 63
87 120 143 158 177 184 186 192 205 217 238 250 252 254
THEME: Evolution of Life and the Solar System Thursday 24 July SURNAME BRON GLIKSON HAINES HAWKE HICKMAN MAIER NORMAN PIRAJNO SALISBURY
FIRSTNAME PAPER TITLE Session Katherine Sedimentary and Petrologic Evidence of a Tookoonooka Impact Event Ejecta Layer, Australia J8 Andrew Direct field evidence for Archaean and early Proterozoic Eros-scale asteroid impacts and K8 major geodynamic consequences, Kaapvaal and Pilbara Cratons. Peter The impact of impacts: impact as a geological process and significance in economic geology. J8 Phil The geophysical signatures of Australia's meteorite impact structures J8 A newly discovered meteorite impact crater, Opthalmia Range, Western Australia. Arthur J8 Confirmed LL chondritic meteorite within the melt sheet of the giant Morokweng impact Wolfgang K8 crater, South Africa. Marc New Perspective on the Lunar Cataclysm from Crater Density Populations K8 Franco Hydrothermal systems associated wiht meteorite impacts K8 Jess Timing of the Lawn Hill Impact Crater and Relationship to the Century Zn-Pb Deposit, K8 Northwest Queensland
Page 60 112 127 129 133 168 189 200 217
THEME: Geoscience in the Service of Society Monday 21 July SURNAME ADAMAS AL - AZAIZEH BANN BROWN DAVID DE SILVA HAGERTY HAWKES SCHAFER SUMNER UNDERSCHULTZ
FIRSTNAME PAPER TITLE Session Sean Sedimentology and Hydrogeology of Goods Road Palaeochannel, Perth, Western Australia C4 Wael Hydrogeology of the Shallow Aquifers at wadi el-Ghussein, NE Jordan B4 Glen Dryland salinity and geodiversity on the Southern Tablelands of NSW: the use of the EM (and C4 AEM) technique for mapping and management? Doug The Role of Hydrogeology in Mining A4 Katarina Looking for mine water supply in the area of limited water allocation (Boggabri Coal, NSW) A4 Landscape evolution and hydrostratigraphy control the development of dryland salinity in the Jayath C4 southwest of Western Australia Sarah The Upper Loddon 'deep lead' palaeodrainage systems are discontinuous due to Mid Tertiary C4 ENE-trending faults. Graham Discovery of a Large Palaeochannel During Exploratory Groundwater Investigations at Glen C4 Innes, NSW David Hydrogeology of the Leederville aquifer near Margaret River B4 Jonathan Ngukurr Groundwater Investigation, Northern Territory, Australia B4 James Petroleum Hydrogeology application to Groundwater Management B4
Page 38 40 48 60 78 80 125 129 218 235 243
Australian Earth Sciences Convention 2008
32 SPEAKER ABSTRACT INDEX by theme / by day
THEME: Geoscience in the Service of Society Tuesday 22 July SURNAME AMANN
FAWCETT GILL HASSAN HILL KOJAN LAMBERT ORMSBY ROBERTSON SEYMON SIMONS SIRCOMBE STEVENS WOODCOCK
Session FIRSTNAME PAPER TITLE D4 From takeover to take off: Issues in managing data transfers and migration in the current Elizabeth frenetic M&A environment. Co-presenters: Sue Grennan, Margaret Ellis E4 Jon Joining forces for (geoscience) knowledge - Groundwater and mineral exploration, same approach, different targets E4 Bruce Application of mineral exploration mapping tools and concepts to groundwater resource evaluation. F4 Lee Mineral potential mapping - geoscientific advice for public policy: an example from Western Australia E4 June Geosyntax: a new computing language for geology data F4 Chris The role of land use geoscience in urban planning and development in the Goldfields of Western Australia D4 Ian The 34th International Geological Congress - AUSTRALIA 2012: Progress and Prospects F4 Warren Titanium-zircon minerals - using geoscience in Western Australia to ensure fliture resource extraction F4 Stuart Resource Mapping: A key ingredient for the mineral resources and development balancmg act in South Australia D4 Adele The Australian mineral occurrence data exchange model E4 Bruce The GeoSciML logical data model of geological concepts F4 Keith A prototype information model and markup language for geochemical and geochronological information. E4 Alexandra Coastal Geographic Information System for the Northern Agricultural Region of the Western Australian Coast D4 Robert Auscope: Australian Earth Science Research Information Infrastructure
Page 41
95 110 128 134 155 157 194 212 225 226 228 233 257
THEME: Geoscience in the Service of Society Wednesday 23 July SURNAME CUMMINS CUNNEEN DEONATH ESTRADA FORSTER GRIFFIN LEONARD LISTER MAZENGARB PRABAHARAN PRENDERGAST QUIGLEY REZAEI
Session FIRSTNAME PAPER TITLE G4 Rupture Characteristics of Recent Tsunamigenic Earthquakes in Australasia, Estimated from Phil Seismic and Sea Level Data H4 The role of geoscience in developing the Indian Ocean Tsunami Warning System Jane G4 Evidence for competing movement patterns influencing the evolution of the Sagaing-Sumatra Abhijit wrench fault system. 14 Towards a better assessment of the seismic hazard in the southwest of Western Australia Beatriz G4 Do strain-rates in deep ductile shear zones reflect seismogenesis at surficial levels of the same Mamie movement zone? H4 Volcano and Earthquake Risk in the Asia-Pacific Region Jonathan 14 Reconciling neotectonic and seismic recurrence rates in SW Australia Mark G4 Gordon Earthquake magnitude in the context of rupture harvesting efficiency in different geodynamic environments. H4 Colin Toward an understanding of tsunami risk in Tasmania H4 D. John Three Dimensional Modeling of Natural Hazards Using Geographic Information Systems H4 Amy Tsunami hazard in south-eastern Australia: preliminary findings from palaeotsunami investigations on the NSW coast 14 Mark Understanding natural hazards using field geology and geochronology 14 Khalil Sediment quality as a factor of the distribution of damage at Bam,iran earth quake
Page 74 75 82 89 102 121 161 166 171 204 205 206 210
THEME: Geoscience in the Service of Society Thursday 24 July SURNAME BANN BAROVICH BRANAGAN BRIGGS CLARK DOWLING FAUZIAH FINDLAY HESS JAMES LEWIS MAZENGARB MCCANN MCNAMARA MCNAMARA
POWELL
Session FIRSTNAME PAPER TITLE KIO Living Geodiversity' - simplified geology maps and linked eco-geo field trips for school and Glen community education JIO Karin Gauging reasons for enrolment in an entry level university geology course: Results of student surveys from 2002-2007 J4 David E.F. Pigot S.J.: The priest who knew about Earthquakes. J3 Alan Rock Tourism and the Black-footed Rock Wallaby K3 Ian The Difference Between a Rock and a Hard Place: Using Geology to Add Value to the Naturebased Tourism Experience J3 Ross Taking Geology to the Public: Geotourism and Geoparks J4 Miftahul Volume change behaviour of unsaturated compacted clay under plane strain condition J4 Robert Rapid uplift and fluvial impact from the Finisterre and Sarawaget Mountains, PNG JIG John Geological Society of America's Public Policy Programs K3 Patrick Geotourism and geoparks promote education for sustainable development KIO Gary Education & Outreach - An outline of the efforts of the Geological Society of America J4 Colin A regional landslide susceptibility programme in Tasmania K3 Doug William Blandowski's 1850s Explorations of the Geology and Landscape of Southeastern Australia KIO Greg Fact-ites, Quizzicles and EarthCaching: The Geological Society of Australia Education and Outreach Initiatives. Where to from here? KIO Greg The Teacher Earth Science Education Programme [TESEP] and Geoscience Pathways: A national scheme to assist teachers and help students discover Earth Science and associated career paths. Co-presenter: Len Altman JIO Trevor Tertiary Geoscience Education in Australia: What future?
Australian Earth Sciences Convention 2008
Page 49 51 59 59 67 84 94 98 133 146 162 171 172 174 175
204
SPEAKER ABSTRACT INDEX by theme / by day
THEME: Geoscience in the Service of Society Thursday 24 July SURNAME FIRSTNAME PAPER TITLE James Fighting the plight: earth science on the march in Western Australia TAHERPOUR KHALIL ABAD Morteza The geotourism potential investigation of Kashmar township (Northeast of iran) TINGAY Mark The 'Lusi' Mud Eruption, Sidoarjo, East Java - A Unique Geological Disaster VAN KRANENDONK Martin Discovery trails to early Earth — a traveller's guide to the east Pilbara
Session JIO J3 J4 J3
Page 214 257 242 244
Session A3 CI A3 B3
Page 54 66 73 74
C5 CI B5 B5 B5 A3 A5 CI
79 79 118 119 122 123 132 137
B3 C3
137 140
THEME: Resources: Foundation for our Future Monday 21 July SURNAME BELL CHOPPING COOMBES CUDAHY DAVIES DE CARITAT GREEN GREENFIELD GRIFFIN GUJ HEITHERSAY HOLDEN HOLDEN HOUSE HUNTINGTON JENKINS JOHNSON JONES LAUKAMP MCDONALD MCNAUGHTON MORRIS MORTIMER PETTS POTMA ROACHE ROBERTS ROGERS SCOTT SCRIMGEOUR SINGOYI SIRCOMBE SMITH WILLIAMS ZHANG
FIRSTNAME PAPER TITLE Jonathan What are in-situ gold resources worth? An empirical study Richard Predicting geophysical targets using reactive transport geochemical models Jacqui The Art and Science of Data Analysis - Building Talent for Future Resource Management Tom Next generation mineral mapping in Queensland: Another piece to the precompetitive geoscience data puzzle. Hugh Geology and Resources of New Guinea Patrice The National Geochemical Survey of Australia: Overview and progress Geoff The TasExplore Initiative and more: Updating the 3-D geological model of Tasmania John New South Wales, New Frontiers, New Opportunities Tim The impact of government pre-competitive geoscience data on mineral exploration in WA. Pietro Australian Junior Exploration Floats, 2001-2006, And Their Implications For IPOs State Survey Initiatives: What have we learnt from PACE? Paul Eun-Jung Interpretation of Aeromagnetic Datasets for Gold and Diamond Exploration: An ImageAnalysis Approach Eun-Jung Automated Polished Slab Image Analysis for Olivine Crystal Size Distribution Detection Hyperspectral Interpretation of Alteration Haloes Associated with Victorian Orogenic Gold Emily Deposits Jon The AuScope National Virtual Core Library - Development of a New National PreCompetitive Data Set David Compiling continent wide datasets for intelligent analysis. James Securing Australia's future wealth. The role of precompetitive geoscience and Geoscience Australia's program. Mai Queensland - Program Initiatives to Attract Exploration Investment - Mai Jones Geological Survey of Queensland Carsten Detection of K-alteration in the Cloncurry District, NW Queensland, using Hyperspectral Mineral Maps Rediscover Victoria in 3D Paul Neal Testing deposit models in the Eastern Goldfields Province, WA: the geochronology perspective using hydrothermal monazite and xenotime Paul Stimulating greenfields mineral exploration:the west Yilgam laterite geochemistry database Nick Mineral exploration in New Zealand: new research framework and tools Anna Studying surface attributes to reveal hidden regolith profiles: Geochemistry and mineralogy of termite mounds of the Coyote Au-deposit and surrounds. Western Australia. Warren Using numerical modelling to target undiscovered gold in a brown-fields environment, an example from Tarmoola, WA. Tony Hyperspectral modelling in mining and exploration: advances in the understanding of structurally-controlled mineralisation Paul Mineral Exploration-related research in the Minerals Down Under National Research Flagship How CRC EEME has provided breakthroughs in exploration through cover-14 years of Steve innovative regolith geoscience R&D. Margaretha Resource Assessment in the Drummond Basin, developing new concepts. Ian Opening up new base metals, uranium and REE provinces in central Australia through precompetitive geoscience Blackwell Relationships between magnetite trace element compositions and mineral paragenesis Keith Field Portable XRF for geological in-situ sampling: calibration and refinement of instrumental precision and accuracy for field measurements Craig Technology advances; neutron activation borehole logging for measurement of elemental abundance, mineralogy, lithology, porosity and hydraulic conductivity Peter Transfer of research initiatives into practice - how effectively are new concepts driving exploration outcomes? Yanhua Numerical Modelling of Strain Localisation in The Laverton Region, Western Australia
B3
142
A3 A5
147 148
A5
149
B1
159
B5 B1
173 175
A1 C5 A1
178 178 198
C3
203
C3
211
A5 A1
211 213
C3 C5
222 223
A1 B1
227 228
B1
229
CI
254
B3
260
Session F1 E8 El E8
Page 39 50 53 56
El D8 F8 E5 F1
56 61 69 82
THEME: Resources: Foundation for our Future Tuesday 22 July SURNAME AHMAD BARNICOAT BEARDSMORE BIERLEIN
BIGGS CAIRNS CLEVERLEY DERRICK EADINGTON
FIRSTNAME PAPER TITLE Sajjad Hydrocarbon prospects of Karak Siwalik Anticline, NW Pakistan: myths and facts Andy Exploration Science Graham Geothermal Systems Analysis-A risk based approach to exploring for geothermal resources Frank A comparative gold prospectivity assessment of the Lake Victoria Greenstone Terrane, NW Tanzania and the Eastern Goldfields Province, Western Australia Co-presenter: Ivo M.A. Vos Mark Challenges in Fault Modelling of Coal Seams Chris Integra Mining's Exploration Strategy and Discoveries-Does one size fit all? James Predicting compositions of white micas in lode gold systems: results of numerical modelling Geoff A Perfect Sulphide Storm at Mt Isa Peter Investigating Petroleum Systems Using Micron-scale Tracers within Sedimentary Grains.
34 SPEAKER ABSTRACT INDEX by theme / by day
THEME: Resources: Foundation for our Future - continued Tuesday 22 July
HAYWARD HOUGH JAIRETH JOHNS
Session FIRSTNAME PAPER TITLE D8 The Psychology of Decision-Making in Mineral Exploration - A Key to Improving Return on Mike Investment in our Business D3 A three-dimensional Weights of Evidence Model for the Drummond basin in NE Queensland: Leonardo quantitative assessment of controlling variables for epithermal Au E3 Application of geomodeller in the Drummond Basin, Queensland Melanie F3 Preliminary Results of a Self Organizing Map Approach to the Integrated Analysis of Stephen Petrophysical Property Data from the Ultramafic-Hosted Seagull PGE-Ni-Cu Prospect, Lake Nipigon, Ontario, Canada El Low-enthalpy geothermal systems driven by convection in fault zones Klaus F1 Early to Middle Triassic stratigraphy of the offshore eastern Bonaparte Basin and Londonderry John D. High, northern Australia. F5 Structure and hydrothermal alteration associated with the Dahongshan iron oxide - copper Matthew (gold) deposit, SW China. F8 The Mt. Mulga barite-iron-oxide-copper-gold mineralisation, Olary Domain, South Australia Martin F3 Using novel prospectivity mapping tools. Self Organising Maps (SOMs), Fuzzy Neural David Networks (FNNs), and Radial Basis Functional Link Nets (RBFLNs), to evaluate the orogenic gold and lOCG potential of Finland FS Nicholas The geodynamic setting and magmatic controls on genesis of world class lOCG ore deposits D3 Megan Predictive Modeling of gold deposits; Walhalla - Woods Point region. Eastern Victoria E3 Subhash Metallogenic Endowment of Cratons, Belts and Districts: Do Bull Elephants roam in Herds? E5 Shannon M. 3D time series mapping of hydrothermal plume behaviour associated with seafloor massive
JONES JORGENSEN
Mai Diane
KHAN
Irfan
LAMBERT LISITSIN
Ian Vladimir
LIU
Keyu
MAMUSE MCAVANEY
Antony Stacey
MUELLER
Andreas
MULHOLLAND MUSGRAVE
Ian R. Robert
SURNAME ETHERIDGE FELTRIN FITZELL FRASER
GESSNER GORTER GREENTREE GRIESSMANN GROVES
NOVIKOVA
Yulia
PARTINGTON
Greg
POKE PORWAL PORWAL RATTENBURY SALAM
Benny Alok Alok Mark Abhisit
SAPPAL SCOTT SCOTT SINGER SOLOMON
Krishna Margaretha Martin Don Mike
SOUTHGATE
Peter
TRIGG WILLMAN WILLSON
Steven Clive Marcus
YEATS
Christopher
sulphides in the Eastern Manus back-arc basin, Papua New Guinea Get closer to the truth ... with hyperspectral mineral maps from Queensland Evaluating the geology and petroleum prospectivity of frontier exploration areas within the offshore north Perth Basin Fracture network evaluation of Samana Anticline: Implication for assessing secondary fracture porosity of the proven reservoirs in the adjacent foreland basin, NW Pakistan Geoscience Australia's Onshore Energy Security Program - the Geothermal Energy Project Quantitative assessment of undiscovered gold endowment in central Victoria - process and implications A Tectono-sedimentary Model for Intracratonic Basin Fill: Examples from the Jurassic Surat Basin, Australia and the Lower Permian Ordos Basin, China A Benchmark for Best Practice in Assessing Australia's Mineral Endowment Investigations of the Cultana Subsuite: An outcropping felsic intrusive - hosted Olympic Dam - style alteration system High-Mg monzodiorite-tonalite ± syenite intrusions, skams, and gold deposits in the Eastern Goldfields Province, Yilgam craton, Western Australia A Potential New MVT Province in Laos New geophysical constraints on the extent of the Stawell and Bendigo zones in New South Wales Mapping mineral alteration associated with onshore hydrocarbon seepage using ASTER and Hyperion data Prospectivity Analysis in Action: The Auzex Resources Ltd. (AZX) Story as Applied to Granite Related Mineral Systems in Eastern Australia and New Zealand. Geochemical Survey in the Highlands of Papua New Guinea Bayesian Network Classifiers for GIS-based Mineral Prospectivity Mapping Spatial Mathematical Models for Mineral Prospectivity Mapping Moving from 2D to 3D geological maps of New Zealand. Geological setting, mineralisation and geochronology of Chatree epithermal gold-silver deposit, Phetchabun Province, central Thailand Collie Coal and the Clean Coal Technology 3D Modelling and the implications for Resource Assessment Exploring for Porphyry Cu-Au-Mo in the Gilmore Fauh Zone at Temora, NSW Quantitative resource assessment — A precursor to prospectivity analysis The Neves Corvo (Portugal) massive sulphide deposit: depositional instability in the Lombador lens, and the origin of the sulphur Geoscience Australia, Offshore Energy Security Program: an update of planned marine surveys and initial results. Increasing the scope of mineral prospectivity in the Cobar-Bourke region, New South Wales Central Victorian deep crustal reflection seismic survey 2006: Implications for mineralisation. Technology and Integration: Improving exploration success - the Australian Mineral Fields Philosophy Subsurface alteration associated with actively forming seafloor massive sulfide mineralisation in the Brothers Caldera, Kermadec Arc, New Zealand
Page
96 99 105
107 114 119 121 123 130 139 145 147
D5 D1
149 150
F1
153
El D3
157 165
D1
167
F3 F5
169 172
E8
179
D8 D5
180 182
D1
189
F3
195
E3 F3 E3 D5 F5
201 202 203 206 216
El D5 F8 D3 E5
218 222 223 227 231
D1
231
E8 D5 D8
242 255 256
E5
260
THEME: Resources: Foundation for our Future Wednesday 23 July SURNAME ADAMS BAKER BLEVIN BUTT COOK COOPER DANCE
Session FIRSTNAME PAPER TITLE 15 Provenance of gold in Mesozoic mesothermal mineral deposits in New Zealand Christopher 11 P-T-X Conditions of Fluids in the Sunrise Dam Gold Deposit, Western Australia: Implications Timothy for the Interplay between Deformation and Fluids in Orogenic Gold Systems 12 An Integrated Approach to Geological Screening for Sequestration Potential - An Example Jane from the Darling Basin, New South Wales G5 The composition and crystallography of gold: implications for ore genesis Charles 15 Trace elements in sphalerite: concentration levels and mode of incorporation Nigel G1 Sedimentary Uranium in South Australia's Frome Embayment: A case history of the first Barry discoveries, 1967-1974 12 Carbon Dioxide Storage Sites: from Prospects to Pilots. Tess
Australian Earth Sciences Convention 2008
39 47 57 60 72 73 77
SPEAKER ABSTRACT INDEX 35 by theme / by day
THEME: Resources: Foundation for our Future - continued Wednesday 23 July SURNAME DENTITH FINDLAY FINDLAY FINDLAY GILMORE GORYACHEV HAGEMAN HOUGH LAMBERT LAWRANCE MCQUEEN MERNAGH NEUMAYR NOBLE OLIVER PIRAJNO ROBINSON SHELDON SKIRROW SQUIRE SUTHERLAND TAYLOR THEBAUD THIEL THORNE WALSHE WILSON WRIGHT
FIRSTNAME PAPER TITLE Exploration for Sandstone-Type Uranium Deposits in Tertiary Palaeochannels in the South of Western Australia New zircon U/Pb dating from the Mt Coolon mineral district, northern Drummond Basin, Robert Queensland, and implications for regional exploration targetting. The Tolukuma mine, PNG; the structural anatomy of a classic intra-volcanic epithermal gold Robert system Robert Geomorphology, crocodiles and mineralisation in Morobe Province, PNG Phil Metallogenesis of the Koonenberry Belt, northwestern New South Wales Nikolay Gold lode deposits in Orogenic Belts of Russian Segment of the Pacific Rim. Steffen The giant Carajas jaspilite-hosted iron deposits: geological setting, fluid geochemistry and genetic model Robert A n e w view of hypogene and supergene gold: Clues for ore paragenesis and exploration Ian Australia's Uranium Deposits, Resources and Production in a Global Context Louisa Redox-controlled Supergene Gold Enrichment within the Sunrise Dam Palaeochannel Deposit, Laverton, Western Australia. Kenneth Key Geochemical Parameters of the Regolith Terry Isotopic Tracers of Fluid Sources in the Lachlan Orogen Peter Keys to the production of Eastern Yilgam Au deposits: Chemical and structural architecture controls on sites of fluid mixing Ryan Transport and deposition of colloidal gold in saprock fractures. Nick Breccia mechanics as an explanation for extreme geochemical micro-gradients and fluid mixing in the genesis of iron-oxide-Cu-Au deposits Franco The Yanshanian tectono-thermal event in China and associated mineral systems Stuart Fortescue Metals Group Ltd - Creating Shareholder Value from Exploration Heather The meeting of two fluids: Mechanisms for fluid mixing in the crust Roger Uranium mineralising systems: a continuum of deposit styles? Richard Architecture of Archean greenstones at St Ives: a vector to Au and Ni ore Frederick Lin Gem corundum sources. West Pacific margins, links to former spreading rifts David Victoria's Proterozoic basement intimately controlled the distribution of its coastal petroleum basins and the subsequent Cainozoic landscape evolution of the highlands. Nick The Paddy's Flat Gold District (Murchison, W.A.): Insight into rheologically and structurally controlled gold mineralisation Stephan Three-dimensional magnetotelluric imaging of the Central-Western Gawler Craton Warren RIO Tinto Iron's concealed high grade #2 lens; product of hypogene and hydrothermal fluid processes, Paraburdoo Western Australia. John Keys to the production of Eastern Yilgam Au deposits: Mixing oxidized and reduced mantle fluids Steven South Jimblebar,Newman - an integrated team approach to an iron ore discovery. An organogenic model for carbon sequestration David Mike
Session G1
Page 81
13 15
97
H5 H5 15 HI
98 96 111 115 124
G5 G1 G5
139 158 160
13 15 II
176 176 187
G5 II
188 192
H5 HI 11 G1 G5 H5 12
201 212 226 228 233 236
13 13 HI
238 239 239 240 249
HI 12
256 258
THEME: Resources: Foundation for our Future Thursday 24 July SURNAME BEAMS BERESFORD COLLINS COLLINS DOYLE FIORENTINI
FOSTER GODEL GREGORY HUSSEY JACOB KENDRICK LARGE MAIER MCCUAIG MILLER MUCCILLI MYERS SCHAUBS SWEETAPPLE TIMMS
FIRSTNAME PAPER TITLE Session Geology and Mineralization of the Rocklands Copper Deposits, Cloncurry District, North K1 West Queensland Advances in magmatic Ni-Cu-PGE exploration geoscience: challenging dogma and J5 Stephen developing new ideas for an evolving search space Geological History of the Flying Fox Nickel Deposit, Forrestania Greenstone Belt, Yilgam K5 Jane Craton, Western Australia: A Preliminary Assessment Peter Magmatic V-Ti-Fe mineralization at Barrambie, Western Australia K1 Mark Tropicana Deposit: a new gold province in Western Australia K4 Marco Role of volatiles and metasomatised sub-continental lithospheric mantle in the genesis of K5 magmatic Ni-Cu-PGE mineralisation: a case study from the Valmaggia ultramaflc pipe, IvreaVerbano Zone (NW Italy) Jeffrey Key controls on the genesis of giant magmatic sulfide systems with special reference to source K5 controls and multi-stage sulfide saturation. Belinda The Merensky Reef of the Bushveld Complex (South Africa): a X-ray computed tomography, J5 microstructural, geochemical and mineralogical study Ian A Collaborative Approach to Developing a Nickel Exploration Model in the Lake Johnston K5 Greenstone Belt Kelvin Constraints on the genesis of the Nolans Bore REE-P-U-Th deposit, Northern Territory, K1 Australia Ann Fluid inclusion and mineral chemical constraints on magmatic origin for metals, Cloncurry K1 iron-oxide-Cu-Au district, NW Queensland Mark Links between orogenic-gold and mantle degassing of 40Ar plus methane K4 Ross An alternative model for the genesis of gold-arsenic deposits hosted in black shale and J1 turbidite successions Wolfgang The Kabanga nickel deposit, western Tanzania J5 T. Campbell The gold mineral system: do we know what we don't know? J1 John Multiple gold events at Laverton, Eastern Goldfields Superterrane, W.A. J1 Peter Widgiemooltha Mine Observations of a Type 1 Komatiite Nickel Deposits and Implications for Exploration. K5 John What does the regional setting of the Voisey's Bay nickel deposit tell us about where to find similar deposits? J5 Peter Structural controls on mineralisation at the Wyoming Gold Deposits, NSW: inferences from deformation - fluid flow numerical models J1 Marcus A genetic model for regional zonation and evolution of mineralized pegmatites from the Archaean Wodgina pegmatite district, Pilbara Craton, Western Australia K1 Structural Controls and U-Pb age constraints for gold mineralisation at Yaloginda, Murchison Nick province. Western Australia K4 Simon
Page 52 54 70 71 85 99
104 113 120 142 145 153 159 168 173 177 179 183 219 236 241
Australian Earth Sciences Convention 2008
SPEAKER ABSTRACT INDEX by theme / by day
Posters
Session Page FIRSTNAME PAPER TITLE Isabella Nature and Origin of the Sogeri Plateau volcanic rocks and the associated volcanosedimentary Poster 38 rocks ABIDI Riadh Contribution of the Microthermometrique Study of the Fluid Inclusions in the Celestite from Poster 38 the Ain Allega Ores Deposits, Tunisia Co-presenter/s: Shimi Najet, Htira Nouri ALLCHURCH Shelley Petrographic and geochemical characterisation of chamokitic and cumulate gabbro xenoliths Poster 40 from Coliban Dam, central Victoria, with implications for the evolution of the Lachlan Orogen Poster 41 ALTMAN Len The Challenging Earth Co-presenter: Amanda Fleetwood BACKE Guillaume Spatial distribution of the seismic activity as a probe to the mode of late Cenozoic deformation Poster 46 in the South Australian Craton: balance between structural inheritance and anomalous high heat flow. Poster 48 BAKKALI Saad The Auto-Regressive Model (Arm) Approach to Denoising Moroccan Resistivity Data Phosphate "Disturbances" Map Poster 58 BOTTRILL Ralph Petrology of the Savage River Mine sequences CAPRARELLI Graziella Lava flows in Pickering Crater, Mars: details from Mars Global Surveyor and Mars Odyssey Poster 63 datasets constrain complex lava flooding history. Poster 65 CHESLER Rachel Geochemistry of the West Australian, West Kimberly Province Lamproites. Poster 67 CLARK Chris Mechanical and thermal reworking of the Vestfold Hills, East Antarctica Poster 72 COLLINS William The AuScope Far North Queensland Survey DOVBYSHEVA Tatjana The Simulation of the Quantitative Estimation of the Influence of Processes and Products on Poster 83 the Environment. Poster 88 EISERBECK Christiane Molecular and Isotope Chronostratography of Tertiary source rocks and crude oils Poster 88 EL-HEDENY Magdy Upper Cretaceous trace fossils from western Sinai, Egypt: taxonomic and paleoecological implications Poster 93 FAIRMAID Alison 40Ar/39Ar dating and noble gas and halogen constraints on orogenic gold mineralisation in Victoria, Australia. Poster 95 FAZELVALIPOUR Ardalan Information technology and geoscience: Introducing technology parks and incubators of geoscience Poster 102 FORD Arianne Fluid Flow in 3D Strike-Slip Fault Systems Poster 108 GHAFOR Imad Biometric Analysis of Lepidocyclina (Nephrolepidina) from Baba and Azkand Formations (Oligocene-Miocene) in Kirkuk area,Iraq Co-presenters: Qahtan Ahmad Muhammed Taxonomy and Paleoenvironment of Lepidocyclina(Nephrolepidina) kirkuknesis new species Poster 108 GHAFOR Imad (Foraminifera) from Late Oligocene (Baba Formation) in Kirkuk and Bai-Hassan Oil Fields, (Kirkuk, North Iraq) GORTER Revised stratigraphy of the Triassic (Induan to Camian) in the northern Perth, Carnarvon and Poster 115 John D. offshore Canning basins. Poster 124 Structural Controls on Mineralisation, Bonaventura Prospect, Kangaroo Island, South GUM Justin Australia. Poster 127 The Cleanskin Structure: a preliminary report on a large impact structure in the HAINES Peter Mesoproterozoic South Nicholson Group, northern Australia. Imaging the Australian Continental Lithosphere with the National AuScope Magnetotelluric Poster 131 HEINSON Graham Facility The Prohibition gold deposit (Murchison, Western Australia), a BIF hosted lode gold deposit Poster 137 HOLLINGSWORTH David with a protracted fluid-rock interaction history. Poster 141 Analysis and Classification of Cosmic Spherules from Lewis Cliff, Antarctica HUI Simeon Poster 147 JOHNSON Possible lateritic paleosol beneath the Earth's oldest (-3.4 Ga) Land Surface in the Pilbara Ian Craton, Western Australia. Poster 151 Status of the impact crater age database. JOURDAN Fred Poster 161 Mathematical Relationships Of Solar System Bodies Revealed Using The Single Body LEE T. Frank Breakup Hypothesis Indicate Radical Rethinking Required Of Early Earth Models. Poster 164 Zheng-Xiang The geodynamic map and evolution history of the supercontinent Rodinia LI QEMSCAN chemical imaging of textures and structures within carbonaceous chondrites and Poster 167 LY ChiV, iron meteorites Tracing paleo-seismic events in the Eastern Mediterranean (Turkey & Israel): U-series dating Poster 190 NURIEL Perach and stable isotope studies of co-seismic carbonate veins. Poster 195 PARTRIDGE Morphological, depositional and temporal controls on sulfur isotopes in pyrite from the Michaela Hamersley Basin, Western Australia PAWLEY The Yamama Shear Zone, NE Yilgam Craton, Australia: geometry, kinematics, constraints and Poster 196 Mark implications. Poster 198 Findings from Regolith-landform Studies at Coyote Au-deposit, Western Australia. PETTS Anna POTTER New sediment datasets help characterise seabed habitats for Australia's Margin: implications Poster 204 Anna for marine environmental planning Poster 208 REDDY Quantitative Characterization of Plastic Deformation in Zircon. Steven Poster 212 RODRIGUEZ MARTIN Jose Antonio Spatial variability of mercury distribution in Spanish Islands soil. Co-presenters: Manuel Lopez Arias, Jose Manuel Grau corbi Poster 215 Schorlomite and Hydrogrossular in a skam in the Northern Red Sea Hills. RUXTON Bryan Consequences of geohazards on rock slope instability along a mountain road, southern Saudi Poster 216 SADAGAH Bahaaeldin Arabia Poster 217 Investigation of Guno storm and their effects on Coastlines Geomorphology of Oman Sea SALEHIPOUR Alireza (Iranian Coast) Constraints from subduction models on mantle flow patterns and the slab to mantle viscosity Poster 220 SCHELLART Wouter ratio Poster 224 3D magnetotelluric array measurements over the Olympic Dam and Carrapateena regions. SELWAY Kate South Australia. SELWAY Earth's oldest subduction zone? Magnetotelluric and structural investigations into the Ubende/ Poster 225 Kate Usagaran eclogites, Tanzania. Poster 237 TAHERPOURKHALILABAD Morteza The creation ability of Tsunami in the South Caspian Basin (North of Iran) Poster 242 TIMMS Nick Zircon Deforms in a Magma Chamber! Depositional controls on stromatolite growth in Earth's oldest-known stromatolitic carbonate Poster 245 VAN KRANENDONK Martin platform: the 3.40 Ga Strelley Pool Chert, Pilbara Craton Poster 247 New insights on the development of the northeastern Murchison domain, Yilgam Craton VAN KRANENDONK Martin Poster 247 Issue with the Precambrian timescale: or, should we stick with what we've got? VAN KRANENDONK Martin
SURNAME ABIARI
Australian Earth Sciences Convention 2008
We aim to help transform the minerals industry in Australia by finding innovative and environmentally friendly new ways to explore for, mine and process minerals. Minerals Down Under National Research Flagship
National Research
FLAGSHIPS
Minerals Down Under
1.75 million ounce resource Discovery at Salt Creek Farm-in partner Barrick Gold in South Australia 168 Stirling Highway Nedlands WA 6009 PO Box 612, Nedlands WA 6909 It 61 (8) 9423 5920 I F: 61 (8) 9423 5930 I info@integramining.com.au
C S i RO
Integra MINING Limited
^
38 ABSTRACTS
alphaisetlcailyfeysyrriam© of presenting aullior
Nature and Origin of the Sogeri Plateau Volcanic Rocks and the Associated Volcano Sedimentary Rocks Isabella Abiari\ Hugh Davies\ Russell Perembo^ and Chris McKee^ 1. Mineral Resource Authorithy, Papua New Guinea, 2. University of Papua New Guinea, 3. Geophysical Observatory, Papua New Guinea. The Sogeri Plateau, 20 km east of Port Moresby, stands 180 to 1000 m above sea level and occupies an area of more than 460 km^. The main rock unit forming the Sogeri Plateau is Astrolabe Agglomerate, a 300m thick volcaniclastic sequence that was formed by the rapid accumulation of a series of water-lubricated debris flows or lahars emanating from a number of eruptive centres. No lava flows are known. An eruptive centre was identified during this study at Mount Tinumu, east of Sogeri. The total volume of the agglomerate probably exceeds 160km^ In the west, at Hombrom bluff, the agglomerate thins, and is underlain by a thick sequence of tuffaceous sandstone (Hombrom Bluff Sandstone, proposed new name), which in turn overlies a volcanogenic conglomerate (Rouna Conglomerate Member, proposed new name). Stratigraphically below the Rouna Conglomerate Member, is a non-volcanogenic conglomerate, the Siro Conglomerate, in which most clasts are low-grade metamorphic rocks. The contact between the two conglomerates is thought to be gradational. The volcanic rocks of Astrolabe Agglomerate have high total alkalis and K2O content exceeds Na20 in many of the analysed samples. Most of the analysed rocks are high-K basaltic andesite, high-K andesite, shoshonite and latite with minor high-K basalt, trachybasalt and dacite. All rocks are porphyritic or microporphyritic, with phenocrysts of plagioclase and chnopyroxene, and less commonly orthopyroxene and olivine, in a finely crystalline groundmass. Chemically the rocks appear to form a single differentiated suite. The Astrolabe Agglomeate was erupted during the latest Miocene-Earliest Phocene uplift of the Owen Stanly range. Trace element abundances and ratios are typical of rocks emplaced during post-collisional uplift (classification scheme of Mueller and Grove, 1995)
Contribution of the Microthermometrique study of the Fluid Inclusions in the Celestite from the Ain Allega Ores Deposits, Tunisia Mr Riadh Abidi^ Mrs Shimi Najet^ Mr Htira Nouri^ Mr Bouhlel Salah^ ^Faculte des sciences de Bizerte ^ Faculte des sciences de Tunis. The mining district of Ain Allega represents one of the most significant deposits of the lyschs zone in the northern of Tunisia. It is located on the Eastern edge of Australian Earth Sciences Convention 2008
the Triassic diaper of Jebel Hamra. The ore are hosted by sedimentary racks belonging the transition zone between Triassic clays and Paleocene marls. The studies of fluid inclusions in the celestite from Ain Allega ores take to these results: - Primary and secondary-type monophase liquid (L) inclusions are most abundant compared to the other types of inclusions. - The microthermometric analyses on inclusion two-phase showed that the fluid mineralisator has temperatures of homogenisation ranging between 1369° and 208 "C with the average of 197.86 °C and of the salinities ranging between 11.34 and 24.38 eq. weight % NaCl with the average of 16.37 eq. weight % NaCl. Therefore, this fluid can be qualified as hydrothermal fluid with a higher salinities characteristic of the basinal brines.
Sedimentology and Hydrogeology of Goods Road Palaeochannel, Perth, Western Australia Sean Adamas^ Mehrooz Aspandiar\ Lindsay Collins \ Ryan VogwilP and Robin Smith^ ^CRC LEME, Department of Applied Geology, Curtin University of Technology (M.F.Aspandiar@curtin.edu.au) ^Department of Environment and Conservation ^Department of Water The westernmost palaeochannel currently found in the Yilgarn Craton is exposed at Goods Road, in the Helena River catchment near Perth, Western Australia. Its sedimentological and hydrogeological characteristics are important to interpreting the Cainozoic geological evolution of the region and for water and biodiversity management of the catchment. The sedimentology of the palaeochannel is dominated by three facies; coarse grained sand to gravelly tabular planar cross-beds, crudely bedded gravels, and horizontally bedded coarse sand. The vertical sequence of the three facies suggests the depositional environment to be a shallow perennial braided "Platte Type" fluvial system. The sedimentology of the palaeochannel differs greatly from the more inland palaeochannels. The sediments and facies present within the palaeochannel are dominated by coarse sand and gravels in contrast to the domination of inland palaeochannel sediments by sand and clay. Both factors elude to higher energy conditions at the western end of the palaeodrainage as compared to the eastern inland areas. The palaeochannel forms an unconfined aquifer enclosed by unconfined weathered bedrock aquifers. It is highly conductive compared to the adjoining weathered bedrock aquifers and therefore acts as a groundwater conduit from these aquifers.
ABSTRACTS alphabettcafiy by surname of presenting author
This can create problems for environmental and water managers when modern catchment drainages intersect these ancient sediments. In summer when groundwater baseflow dominates some surface water courses in the Helena River catchment, the often salty water of the palaeochannel can create negative impact to biodiversity and water resource assets. Water quality results from the palaeochannel, from bedrock seeps and from the mixing zone indicate the palaeochannel groundwater to be less saline than the surrounding bedrock aquifer, but is still salty enough to create unwanted impacts.
Provenance of gold in Mesozoic mesothermal mineral deposits in New Zealand CJ.Adams^ ^GNS Science, PO Box 30368 Lower Hutt, New Zealand (argon@gns.cri.nz) Mesozoic mesothermal gold occurrences are widespread in New Zealand, extending as very minor occurrences in the Wellington area at the south of the North Island, through the South Island in Marlborough and Canterbury Provinces, to the more substantial (and commercial) deposits in Otago. Detailed Rb-Sr metamorphic, and U-Pb detrital zircon provenance ages of the gold host rock metasediments of the Haast Schist (and its protoHth Torlesse Supergroup) indicate that they are invariably of Late Triassic stratigraphic age, and all within the Torlesse (Permian to Cretaceous) composite terrane. The detrital zircon age patterns in these hostrock metasediments, and those of their adjacent terranes, suggest that all the sediments have an ultimate source in northeast Australia. However, the Late Triassic Torlesse depocentres in particular had sediment sources restricted to the central part of the present-day eastern Queensland i.e. TownsvilleCharter Towers region. This may thus suggest that gold-bearing Torlesse sediments of New Zealand may have originated within the classic Paleozoic gold-fields region of Charter Towers. Significandy, other New Zealand terrane sediments, that probably originated north and south of this region, do not host Mesozoic gold.
Hydrocarbon Prospects of Karak Siwalik Anticline, NW Pakistan: Myths and Facts. M Irfan Khan Izabelld^, Athar AW
i, Amjad Ali Khan\ Csiki
^MOL Pakistan Oil & Gas Co. B.V. Islamabad, (irfan. khan@molpakistan. com, ^University of Peshawar, N.W.F.P. Pakistan, (yahya_sajjad@yahoo. com) Saif Energy Limited Islamabad, Pakistan, (amjad.ali@saifgroup.com) '^MOL Pic Hungarian Oil & Gas, Budapest Hungary. IC(siki@mol.hu) ^MOL Pakistan Oil & Gas Co. B.V. Islamabad, (athar. ali@molpakistan. com) The Karak Siwalik Anticline (KSA) is a prominent structural high of the southern Kohat Basin in northwest Pakistan which has emerged as a prolific hydrocarbon bearing province of the country during recent past. An exploratory well namely Karak-1 was drilled by Texas Gulf during 1977-1978 on the KSA which was aimed at Eocene carbonate reservoir. The well was abandoned within Siwaliks at the depth of 4459 meters. Since then the exploration chapter is closed, based on the assumption that Siwaliks are enormously thick and the reservoir is too deep. This article addresses the key issues regarding the hydrocarbon prospects of the KSA using surface and subsurface redefinition and reinterpretation of the data. Current field investigations reveal that the KSA is about eighteen kilometers long, running ENEWSW, is a well-defined, slightly asymmetrical fold with a relatively broad crest. The closure to the NW, west and along the southern flank are well marked. The fold is cut on the north eastern boundary by the Mitha Khel Fault, which is steeply north dipping. The attitude data on the limbs of KSA suggest the presence of a subcrop, south facing thrust fault. The seismic definition of the fold is in harmony with the surface data and depicts two prospective highs at the level of Eocene related to subcrop fault: one in the hanging wall with Eocene top at 3300m depth from ground level and the second one in footwall with Eocene top at 4700m depth from ground level. Geo-seismic transect constructed across the KSA depicts that Karak-1 well was placed around 800 m south of the hanging wall prospect and penetrated the steeply dipping forelimb, the subcrop fault and repeated sequence of Siwaliks and was abandoned approximately 200m above the footwall high. Various oil and gas seepages in the area would appear to indicate that the KSA lies within the oil province and, since the anticline is bounded by wellmarked structural lows, it would be expected that any petroleum would have migrated up the likely reservoirs in the anficline. The reservoir rocks beneath the KSA include Eocene Sakessar Limestone and Paleocene Lockhart/Hangu Formation which are the main producing horizons of the oil fields in adjoining areas.
Australian Earth Sciences Convention 2008
39
40 ABSTRACTS alphabetically by surname of presenting author
"Hydrogeology of the Shallow Aquifers at Wadi el-Ghussein, NE Jordan" Wael M. 1. Al-Azaizeh^ ^Institute of Earth and Environmental Sciences, Al al Bayt University, Mafraq - Jordan Email: wael@aabu.edu.jo The research aimed to better understand the hydrogeology of the alluvial shallow perched aquifers in Wadi el-Ghussein in Tulul al Ashaqif area of the northeast Badia of Jordan. Many generations of local Bedouins have dug wells by hand in the wadi and exploited the available water, which helped to support their water requirements. Recent studies have suggested that these aquifers are renewable, widespread and can be used as a water resource, provided that they are managed in a sustainable manner. This requires a full understanding of the hydrology of the aquifer. Several techniques were used to collect data needed to better understanding of the hydrological situation in Wadi el-Ghussein. Total station surveys were used to draw a detailed topographic map for the study area, and hydrometers were used to check the elevation of the groundwater, and to draw ground water contours directly. Very low frequency geophysical equipment (VLF) were used to determine the lateral extents and depths to the groundwater level along different profiles of the wadi and under the basalt pavements where direct measurements were not available. Samples of groundwater were collected for geochemical modeling and to check for the quality of the water. Analysis of the results of data led to determine the flow directions of water, which were confirmed by geochemical modelling. The general groundwater flow direction is from outside the wadi (basalt pavement) towards the center of the wadi and from the NW towards SE along the course of the wadi. Within the wadi, areas where recharge and discharge (towards deeper aquifers) were clearly detected. Geochemical modeling confirms these conclusions. VLF data analysis also indicate that lateral extents of water is limited to the wadi bed, except in limited areas such as meanders where groundwater extends under some points of the basalt pavement. Water quality is close to the permissible Jordanian and World Health Organization (WHO) standards, and the plot of the chemistry of the sampled water on the Piper diagram led to it's classification as carbonate water.
Australian Earth Sciences Convention 2008
Petrographic and geochemical characterisation of charnokitic and cumulate gabbro xenoliths from Coliban Dam, central Victoria, with implications for the evolution of the Lachlan Orogen Shelley Allchurch^ Dr Ian Graham^ Dr Nathan Daczko^ ^ GEMOC, Dept. of Earth & Planetary Sciences. Macquarie University, North Ryde NSW 2109, A ustralia (sallchur@els. mq. edu. au; ndaczko@els. mq. edu. au) ^ School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney NSW 2052 (i.graham@unsw.edu.au) A variety of xenoliths hosted by basaltic icelandites of the Newer Volcanics (^-2.5 Ma) were examined from the Coliban Dam area, near Kyneton in central Victoria. These include two dominant main suites (a textural and compositional range of charnokitic granulites and cumulate gabbros) along with rarer relatively unfoliated equigranular granite and massive trachyte. The charnokitic granulites are particularly important as they are possibly the oldest crustal rocks so far discovered within the Lachlan Fold Belt of eastern Australia (Graham et al, 2006, AESC Abstract). Zircons separated from the charnokitic granulite were examined using cathodoluminescence imaging and found to be clearly of the magmatic type, with narrow metamorphic overgrowths. Subsequent SHRIMP dating showed two ages of around 580 Ma and 400 Ma. Cross-cutting relationships between the suites reveal the charnokitic granulite to have first crystallised at around 580 Ma (Neoproterozoic), folded, then intruded by the cumulate gabbros at -400 Ma (Early Devonian) (Graham et al, 2006, AESC Abstract). This study directly dates the cumulate gabbro suite using the LA-ICP-MS U-Pb technique. The charnokitic granulite of Neoproterozoic age provides evidence of ancient continental crust known as the 'Selwyn Block'. We present geochemical analyses of both xenolith suites including Sr, Nd and Lu-Hf isotopes, laser ablation U-Pb dating, petrology and metamorphic analysis to provide further insight into the 'Selwyn Block'. We constrain source composition, conditions of emplacement, metamorphic history and the relationship between the two xenolith suites to allow a better understanding of the Lachlan Orogen with emphasis placed upon the charnokitic granulite and its role in the early evolution of the Lachlan Fold Belt.
ABSTRACTS alphabetically by surname of presenting author
Dust to Planets - what have we learned from Genesis and Stardust Samples? J. H. Allton\ C. C Allen ^NASA Johnson Space Center, Houston, Texas, 77058, USA. Genesis Mission and Stardust Mission samples are uniquely valuable for deciphering the details of planetary formation in that time after the sun "came to light" and the residual dust and gas coalesced into the planets. Genesis provides laboratory samples of the solar wind, with potential to allow many, precise elemental and isotopic measurements of solar composition - the material comprising 99% of solar nebula material. Genesis samples consist of highly pohshed, ultra-pure surfaces with solar nuclei imbedded in the top 100 nm. Analytical results from the Genesis solar wind samples are being achieved more slowly, after considerable effort to clean off surface contamination, which was mosdy derived from the hard landing. The hard landing also reduced original collector size to many smaller fragments; however, even small fragments yield solar composition. Earliest results were for noble gas isotopes, because these species are less affected by contaminants. Progress has been made on nitrogen and on iron, magnesium and other transition elements. Most of the measurement goals are expected to be achieved. Genesis' primary goal, oxygen isotopic composition of the sun, is in work by the Science Team. To the collection of planetary samples for analysis, the Stardust Mission adds a bonanza of particles from comet Wild 2. The Stardust grains provided a few surprises - crystalline grains that formed at high temperature. The majority of Wild 2 solids are solar system materials that appear to have formed over a very broad range of solar distances and perhaps over an extended time range. The field recovery and curation of Genesis and Stardust will be compared. Both collections provide reserve of samples for future investigations.
The Challenging Earth Mr Len Altman^ Ms Amanda Fleetwood^ ^ Harden Senior College, Adelaide, SA, Australia In the last decade the number of students studying senior secondary science in Austraha and internationally has declined significandy. The Perth Declaration on Science and Technology Education (July 2007) for example, which followed from the deliberations of 1000 science and technology delegates from 50 nations worldwide recommended that Governments:
''...initiate revisions of the curriculum for school science and technology that will //icrease student interest and recognition of the roles of science and technology in society The Teacher Earth Science Education Program (TESEP) aims to address the cridcal national shortage of young people taking up positions in trades and professions in the Energy/Minerals and related Science and Technology industries. TESEP's aim is to develop state-of-the-art, muldmedia teaching resources for The Challenging Earth series, for Years 7 to 10 secondary students. Fully funded teacher training and professional development workshops are planned for up to 200 teachers in capital cities, regional centres and rural and remote school regions throughout Australia, over the years 2008 to 2010. New teaching resources from TESEP, as well as those from the acclaimed Western Australian ESWA, Queensland Resource Council and Minerals Council Australia programmes will be shared across Australia. These new teaching and learning resources will help teachers foster ongoing student interest in science and will enhance the development of scientific and environmental hteracies during the middle years of schooling TESEP also recognizes the need for all students to have access to quality curricula that facilitates their engagement and factual learning about the planet Earth, from a critical thinking and scientific point of view whether or not they might aspire to careers in science. This exposure will empower their participation in informed debate about vital contemporary issues affecting all. It is particularly timely to launch The Challenging Earth series during the International Year of Planet Earth (2008). The TESEP programme has been seedfunded and is managed by the Petroleum Exploration Society of Australia (PESA) and has been developed under the auspices of the Australian Science Teachers Association (ASTA). This session will introduce and demonstrate the first completed units of the The Challenging Earth series and the Geoscience Pathways website, which will become the repository for these and other new education resources for schools. Wider participation and involvement in this exciting project will be fostered and invited.
From Takeover to Take Off: Issues in Managing Data Transfers & Migration in the Current Frenetic M&A Environment Mrs Elizabeth Amann\ Mrs Sue Grennan^ Mrs Margaret Ellis^ ^ BHP Biliton Nickel West ^ Geological Survey of Western Australia continued next page... Australian Earth Sciences Convention 2008
41
42 ABSTRACTS alphabetically by surname of presentmg author
Much Ni & Au ground was divested during the late 1990's to early 2000's. The accompanying data compilations was/is seen as a valuable trading commodity and often attributed an intrinsic value. However usually there is an overwhelming amount of data involved and in areas where exploration has had a long life-span, the data has had numerous derivations, and exists in a variety of formats, conditions, and repositories. The acquirer wants all data entitled, however the supplier also needs to protect potential future interests. Complicating issues included the fact that the current ground-swell of geoscientists, accountants and lawyers who are floating/populating the up coming juniors & new ventures originated from the majors and are acutely aware of the historic data stores available and the expectation is to gain all data in a useful condition. Sourcing and packaging data for handover, and then compiling and making use of that acquired data after receipt present issues, some which are surprisingly similar for both parties. Timing is critical for both vendor and purchaser - the supplier must legally comply with conditions of agreement and the receiver needs to translate that data into useful information for on ground targets and exploration/mine planning as quickly as possible. Using industry examples of issues involved in recent mergers and acquisitions, the paper will concentrate on issues relating to management and logistics of data transfer during a sale or joint venture agreement, both from supplier and receiver point of view.
Dating Fractionation of Refractory and Volatile Elements in the Protoplanetary Disk Yuri Amelin^ and Trevor Ireland^
^ Research School of Earth Sciences, The Australian National University, Canberra ACT 0200 (yuri. amelin@anu. edu. au) Recent isotopic studies suggest that the parent asteroids of differentiated meteorites, and probably terrestrial planets as well, formed very early, within 1-2 Ma after condensation of the first Solar System solids. Accretion of these volatiledepleted bodies preceded accretion of the more volatile-rich parent asteroids of chondrites. Knowing the timing of this large-scale fractionation of refractory elements from the volatile-rich nebula is important for understanding the evolution of the protoplanetary disk. Dating the volatile - refractory element fractionation requires using isotopic chronometers made of the parent and daughter elements with considerably different condensation temperatures, for instance ^^Mn-^^Cr and U-Th-Pb. The initial Sr chronometer is particularly well suited for dating Australian Earth Sciences Convention 2008
accretion of volatile-depleted asteroids. It can potentially "see through" igneous processes and date the volatile depletion (and hence accretion) directly for the materials strongly depleted in alkaline elements, such as eucrites, angrites and lunar rocks. Despite the early success (Papanastassiou and Wasserburg 1969, Gray et al. 1973), the initial Sr chronometer fell into oblivion since the early 1990's. The main reason why this method was discontinued was the insufficient time resolution that was limited by the precision of Sr isotopic analysis . The difference of 0.005% in ^"^Sr/^^Sr (similar to the typical analytical precision in the early studies) corresponds to a ca. 2 Ma difference in the age, assuming the Rb/Sr ratio in the solar photosphere or in CI chondrites. Modern thermal ionization mass spectrometry can yield 5-10 times better precision, thus making the initial Sr dates as precise as the ^^Mn-^^Cr andU-Pb dates. We started re-examination of the initial Sr isotopic composition of CAIs, eucrites and angrites using the acid-washed mineral fractions already dated with the high-precision U-Pb method. The first resuhs will be reported at the AESC-2008 meeting.
How Pisoliths Form
Ravi Anand^ and Michael VerralP ^CSIRO Exploration and Mining (CRCLEME), PO BOX 1130, Bentley, Perth, (ravi.anand@csiro.au) ^ CSIRO Exploration and Mining, PO BOX 1130, Bentley, Perth. There have been interest in pisoliths because of their economic importance and mode of formation. They are spherical particles zoned at a sub-millimetre scale, composed of goethite, hematite, maghemite, kaolinite, amorphous alumina, gibbsite with and without quartz. They are ubiquitous in regolith of the Yilgarn Craton. Pisoliths have also been reported to occur on Mars. They have distinct morphologies and their nuclei comprise either: (a) an older hematite-maghemite nodule; (b) ferruginous clay; (c) fragments of older goethite pisoliths or; most commonly, (d) goethite or hematite-replaced fragments of wood. Cores of fossilised wood contain pseudomorphs of xylem vessels of angiosperms. Most of the xylem are covered by rod- shaped and spherical growths of goethite. Cutans are mostly fully concentric, with the innermost cutan increasing in thickness so as to fill and smooth out depressions in the nucleus surface. Rod shaped and spherical (0.1-0.3 |um) nanocrystals of goethite are most common in the cutans. The external shape of composite pisoliths appears to be near spherical regardless of nucleus shape. The formation of pisoliths is complex, as no two pisoliths are the same. Each pisohth has its own history of formation. More commonly, concentrically zoned pisoliths form by accretion of
ABSTRACTS alphabetically by surname of presenting author
Fe-oxides and clay around a particle under changing regolith conditions. This mode of pisolith formation is fundamentally different to that in which cortical laminae develop by the progressive inwards ferruginisation of a progenitor particle. Pisolith formation is probably a very slow process. No estimates of pisolith growth rates are known, but a period of some thousand to tens of thousands of years for a large pisolith seems reasonable. Complex interaction between biotic and abiotic processes in the weathered environments may provide a model for the formation of Martian pisoliths.
Geosdence and Food Traceability Anita S Andrew^ Garry SH Lee^, Russell D Frew^, John Watling\ David Hill^ and G. Stewart Walker^ ^Environmental Isotopes Pty. Ltd., North Ryde NSW 2113, Australia (anita.andrew@isotopic.com.au) ^Food Science Australia, North Ryde, NSW 2113, Australia (Garry.Lee@csiro.au) ^University ofOtago, Dunedin. New Zealand (rfrew @ alkali, otago. ac. nz) "^The University of Western Australia, Crawley, WA 6009, Australia (john.watling@uwa.edu.au) ^ANSTO, Menai, NSW 2234, Australia (David. Hill @ ansto. gov.au) ^Flinders University, Adelaide, SA 5001, Australia (Stewart. Walker@flinders.edu.au) The advent of free trade agreements and globalization of the world markets has increasingly led to fraudulent behaviour amongst traders attempting to increase profits by deliberately mislabeUing or adulterating high-return quality foods with sub-standard produce. Australian and New Zealand food produce has a premium position in export markets as they are considered of superior quaUty and free of contaminants like pesticides. To maintain this competitive advantage and mitigate issues of fraud, new tools are needed to monitor the origin of foods. While chemical methods have been used successfully to combat fraud in food, they provide limited information about the geographical origin of the food. Isotope ratios and trace elements offer methods to differentiate between chemically identical substances through differences in their elemental fingerprints. Many natural phenomena, for example, evaporation and condensation, photosynthesis and the uptake of nutrients, lead to isotope fractionation. Trace element and natural abundance isotope analysis provides information on plant 'type' or diet (C and N), and geographical origin (trace elements, H, O, N, S, Sr and Pb). The application of technology to verifying the origin of food commodities is limited by the paucitv of reference data and a concerted
The apphcation of technology to verifying the origin of food commodities is limited by the paucity of reference data and a concerted development effort is required. Presently, Australia and New Zealand lack the infrastructure for tracing the origin of foods. The PROOF (PRoof Of the Origin of Foodstuffs) network aims to deliver a robust traceabiUty program by building upon relationships with similar organizations such as the European Commission's TRACE project.
Ritter Volcano, West Bismarck Arc: tsunamigenic collapse and peridotite xenolith locality. Richard Arculus\ Chris Yeats^, Scientific Party SS06/2007 ^ Research School of Earth Sciences, ANU, ACT 0200 (Richard.Arculus@anu.edu.au) ^ CSIRO Exploration &Mining, Bentley, WA 6102 (Chris. Yeats(@csiro.au) Research Voyage SS06/2007 of the Marine National Facility (RV Southern Surveyor) explored the West Bismarck and New Britain island arcs of PNG for active tectonism, submarine volcanism and hydothermalism in July-August of 2007. Among many targets investigated, the debris field resulting from the largest historic lateral collapse of an island volcano, that of Ritter in March 1888, was mapped with a high resolution 30 kHz multibeam sonar system. Ritter is located at the north end of the Dampier Strait between Umboi and Sakar. The debris field runs to the northwest for several 10s of km, characterised near source by a hummocky surface. An active vent has developed within the centre of the former 800m-high cone. The debris field envelops several cones, one of which is hydrothermally active, and a number of which are covered with peridotite- and gabbro-cored basaltic bombs.
Australia and the Integrated Ocean Drilling Program. Richard Arculus Research School of Earth Sciences, ANU, ACT 0200 (Richard.Arculus@anu.edu.au) Together with a number of international partners in a number of different consortia, Australia benefited immensely from membership of the international Ocean Drilling Program (ODP), which revolutionized our view of Earth history and global processes through ocean basin exploration. Our
continued next page...
Australian Earth Sciences Convention 2008
43
44 ABSTRACTS afphabetlcaily by surname of presenting author
benefits stemmed from a disproportionately large share of drilling legs within waters of Australian interest, co-chief positions, and exposure to international best-practice in marine geoscience. The termination of the ODP in 2003 was followed by the establishment in 2004 of the Integrated Ocean Drilling Program (lODP), which is using multiple drilling platforms, including riser, riserless, and mission-specific, to achieve its scientific goals. After several years of effort supported by MARGO with legacy funds from ODP involvement, a bid for ARC LIEF funding has been successful allowing "associate membership" for Australia in lODP, commencing in 2008. It is anticipated that New Zealand will join us in a consortium likely to be called Australia New Zealand Ocean Drilling (ANZOD). We have already placed our first shipboard scientist aboard a drilling leg in the Nankai accretionary prism being conducted by the state-ofthe-art riser-equipped Japanese drilling vessel {Chikyu). Scientists interested in participating in future lODP legs should contact Neville Exon or Richard Arculus at the ANU.
In situ measurement of sulphur isotope ratios: new developments and results using the SHRIMP 11. Richard A. Armstrong\ Peter Holden\ Ian S. Williams^ ^Research School of Earth Sciences, The College of Science, The Australian National University, Canberra 0200, ACT, Australia, (richard.armstrong@anu.edu.au) Sulphide minerals are the most important group of ore-forming minerals and thus have enormous economic interest. Studies of sulphide isotope geochemistry provide fundamental information on the genesis of these ore deposits, but also provide unique information on the geochemistry and evolution of mantle, crustal, hydrothermal, biogeochemical and atmospheric systems, and the processes within and between these reservoirs. This information is gathered from the measurement of the natural variations of the stable sulphur isotopes, recording mass-dependant and mass-independent fractionation from a variety of processes. Sulphur isotope ratio measurements are made using a number of methods, but early work by Hdridge et al. (1988, Econ. GeoL, v. 83, 443-449) showed the advantages and insights to be gained from in situ analyses using the high spatial capabilities of the SHRIMP I (Sensitive High Resolution Ion Micro Probe). This technique allows the measurement of isotope ratios on -20 mm spots in a variety of sulphide minerals. Recent technical developments on the SHRIMP II instrument at the Research School of Earth Sciences, ANU, have allowed further advances to be Australian Earth Sciences Convention 2008
made on this technique, opening new avenues in research in ore systems. In particular, the dual developments of a Cs+ primary ion source and a multicollector system have increased the analytical capabilities for studies of sulphur isotopes, and indeed, other stable isotopes. A major effort has been made to fmd and characterise suitable sulphide mineral standards of sufficient homogeneity and covering a range of compositions. These standards have been used to accurately measure the isotope ratios in a number of ore deposits, including Au-bearing horizons of the Witwatersrand Basin, magmatic systems of the Bushveld Complex and a number of other deposits from various environments and settings. These results will be presented, together with a discussion of the technique and it's potential and limitations.
Mantle melting Nick Arndt^ ^ LGCA, Universite de Grenoble, 1381 rue de la Piscine, 38401 Grenoble. France (arndt@ujfgrenoble.fr) Rising parts of the mantle, such as upwelling parts of convection cells or plumes partially melt because the decreasing pressure normally decreases the solidus temperature of mantle peridotite. Under most circumstances the melt is less dense than the solid residue and it escapes upwards and out of the source. In most cases melts from different parts of the melting zone mix together and hybrid or "pooled" melts erupt at the surface. Controls on melt composition include (1) the temperature of the source, which directly influences the degree of partial melting. The hottest parts of the modern mantle, represented by Gorgona komatiites, were some 200-300° hotter that ambient mantle and the maximum degree of melting was about 30%. The sources of alkali basalts were cooler and their degree of melting was only a few percent. (2) The depth (or pressure) of melting. Most melting is polybaric. The start of melting is deepest for the hottest sources (>300km for komatiites); melting ceases when the source reaches the base of the lithosphere (3) the melting mechanism (fractional or equilibrium) strongly influences the trace element compositions. (4) The composition of the source has only a minor control on major elements but a profound effect on trace element and isotopic compositions. Peridotitic and eclogitic components can be recognised in the sources of most magmas using a combination of mineral data and trace-element or isotopic compositions. Parts of the lithospheric mantle are metasomatised but the degree to which such sources contribute to high-volume magmatism remains uncertain.
ABSTRACTS alphabetically by surname of presenting author
Some natural and anthropogenic sources of groundwater contamination in the Himalayan mountain belt.
Recognition and geological significance of Cenozoic Paleosols in the regolith profile
Dr M Asim Yousafzai
Mehrooz F Aspandiar
^University Of Peshawar
CRC LEME, Department of Applied Geology, Curtin University of Technology Perth, WA 6845 e-mail: M.F.Aspandiar@curtin.edu.au
Water samples were analyzed for major and trace elements from the Pakistani Himalayas. The study area can be divided into two hydrogeological provinces. The northern province is mountainous and the water table varies in depth in different intermontane valleys. Abundant springs (normal and high temperature) are present in this part of the study area and they constitute an important source of drinking water. The outflow from these springs ranges from less than a gallon per minute to more than 500 gallons per min. The southern province of the study area consists of the Indus platform and the foredeep which are covered by unconsolidated Quaternary deposits attaining a maximum thickness of 500 m. This portion can be divided into isolated basins bordered by mountains on one or all sides. The basin sediments constitute well-productive aquifers and consist mainly of sand and gravel in the north and south of the basin. The analyses indicate low levels of contaminants in some of the spring water, however, water from deep and shallow wells indicate contaminants well over the Maximum Contaminant Level (MCL) set by the UwS Environmental Protection Agency. The analyses did not show any amounts of Arsenic, Cobalt, Mercury, and Nickel. Copper was found in only one sample and its concentration is within the limits of EPA. The amounts of Cadmium, Chromium, Iron, Lead, Nitrate, Sodium and Chloride exceed the MCL. Total Dissolved Sohds (TDS) also exceeds the MCL in many samples. Aluminum, Barium, Fluoride, Silver, and Zinc values fall within the MCL. Higher levels of contaminants in the spring water can be attributed to the natural sources of contamination and agricultural activities. However, contaminants in the well water can be traced to the industrial sources as well. Natural as well as anthropogenic sources of contamination (both point and non-point) are present in the studied area.
Due to deep and multiple weathering imprints, paleosols are difficult to recognize in the Australian regolith. The recognition of paleosols is critical to interpreting paleo surface processes and landscape evolution and enhancing our understanding of regolith and landscape evolution models. Examples of previously unrecognized Cenozoic paleosols from Charters Towers in North Queensland showcase the importance of correctly recognizing paleosols for geological and landscape evolution. The multi-storey, laterally restricted red and yellow paleosols were recognized from differentiated soil horizons, drab root traces or redoximorphic features, rhizoliths and clay cutans. The paleosols were developed in a mud dominated fluvial landscape and are interpreted to form due to the long term evolution of a fluvial landscape. The significance of recognizing paleosols in weathering profiles is threefold. Firstly, they provide information on landscape evolution where their presence argues against interpreting ferricrete capped formations as representing phases of sedimentation followed by weathering periods, especially in fluvial dominated landscapes. Secondly, they show the presence of multiple but laterally limited erosion-sedimentation events in the transported part of the regolith profile rather than a single unconformity. Thirdly, their spatial and temporal variability argue against using weathering periods and features as morpho and chronostratigraphic markers.
The Quest for Perfection - Biogenicity and the Early Fossil Record Stanley M. Awramik^ ^ Department of Earth Science, University of California, Santa Barbara, CA 93106, USA (awramik@geoL ucsb. edu) Reports on the Earth's earliest fossil record have often been greeted with skepticism. The classic example is ''Eozoon canadense^ described by Dawson in 1865. Although ''Eozoon" turned out to be a non-fossil, the initial impact was apparent (e.g., in 1866 Darwin mentioned it in his edition of the Origin). It's been 143 years since ''Eozoon'' and things are much the same: New discoveries are received both positively and
continued next page...
Australian Earth Sciences Convention 2008
45
46 ABSTRACTS alphabetically by surname of presenting author
skeptically. Western Australia has played prominently in early life discoveries and controversies, as has Greenland and South Africa. Evidence for this life included chemical signatures and biomarkers, microbial fossils, and stromatolites. What have we learned and where do we stand? Suggestive evidence for hfe's existence is found in -3.83 Ga-old rocks from Greenland. Presumptive evidence for diverse bacterial life, some of which were phototrophic, comes from -3.45 Ga-old rocks in Western Australia. The oldest compelling evidence of life comes from -1.87 Ga-old rocks in Canada. Why is the 3.4 Gaold evidence from Western Australia only presumptive? Simple, debate still exists. It is likely that evidence will elevate to compelling; however, currendy the preponderance of evidence indicates a most likely biogenic interpretation, but less probable interpretations also merit consideration. Stromatolites might actually represent the most reliable evidence for early life. A cascading stream of information is available for most any stromatolite. Information proceeds from the geologic and stratigraphic context to the distribution and orientation of the stromatolites in outcrop to stromatolite shape, geometric arrangement of laminae, the nature of laminar boundaries, the microscopic fabric and texture of laminae, mineralogy, chemical signatures, and microbial remains. These data coupled with the large body of knowledge from younger stromatolites, can make presumptive and compelling cases for the biogenicity of any stromatolite. It's not a perfect world and the fossil record is not known for perfection.
Spatial distribution of the seismic activity as a probe to the mode of late Cenozoic deformation in the South Australian Craton: balance between structural inheritance and anomalous high heat flow. Guillaume Backed Graham Baines\ David Giles^ ^ Centre for Mineral Exploration Under Cover, School of Earth and Environmental Sciences, University of Adelaide, South Australia, 5005 (guillaume. backe@adelaide. edu. au) The occurrence of earthquakes in stable continental interior is triggered by either an anomalous high heat flow within the crust or preexistence of a zone of weakness. The South Australian Craton, located in the central part of the Australian plate, has recorded a continuous history of deformation since the Mesoproterozoic. It has been subjected to various tectonic events related to the building and break-up of paleo-continents and the amalgamation of Australia. This area, today located more than 1000 km away from the nearest active plate-boundary, Australian Earth Sciences Convention 2008
displays a seismic activity of moderate intensity predominantly following the trend of the Neoproterozoic Adelaide "Geosyncline". Deformation in this basin has been previously related to an anomalous high heat flow, referred to as the South Australian Heat Flow Anomaly, caused by high heat producing granite present in the basement rock of the craton. However, few studies have focussed on the spatial distribution of the hypocentres of earthquakes in the South Australian Craton. The link between the seismic activity and the geology is poorly understood as the significant thicknesses of sedimentary cover and regolith have so far inhibited our understanding of the architecture of the basin at depth. Here, ve use surface geology together with gravity and magnetic data to build a regional-scale structural frame in order to better constrain the role of tectonic structures, in particular faults affecting the basement rocks of the basin, in the distribution of earthquakes. We show that not all of the recent deformation and modern landscape in the South Australian Craton can be related to high-heat producing rocks. On the contrary, our observations highlight the strong link between the inherited architecture of the basement and the intraplate seismicity and landscape evolution in cratonic areas.
Basement faults control over salt-driven tectonics in the Central Flinders Ranges, South Australia.
Guillaume Backe\ David Giles\ Graham Baines^ ^ Centre for Mineral Exploration Under Cover, School of Earth and Environmental Sciences, University of Adelaide, South Australia, 5005 (guillaume. backe@adelaide. edu. au) The Central Flinders segment of the Adelaide basin in the central part of the Australian plate recorded a series of rift and basin cycles followed by partial tectonic inversion from the Neoproterozoic onwards. The deposition of evaporitic sediments during the late Neoproterozoic (Willouran age) in the Central Flinders has played a major role in the subsequent tectonic evolution of the basin, to such an extend that this area is described as being the best preserved field analogue of salt-driven sedimentation and tectonics in the world. Previous works have put the emphasis on the early mobilization and withdrawal of the evaporites and its vertical transport across the overlying sedimentary cover during the sedimentation of the Early Cambrian Bunker Sandstone Fm. which is part the Hawker Group. Other works have highlighted the role of these evaporites during the Cambroordovician Delamerian orogeny, and the influence
ABSTRACTS alphabetically by surname of presenting author
on growth of the fold and thrust belt in the Central Flinders. However, very few studies have focused on the control exerted by pre-Adelaidean basement structures in the deposition of evaporitic beds and their influence in the latter inversion of the basin. Here, we use published geological maps, analysis of satellite imagery and aerial photograph, field work, interpretation of seismic refraction profiles and interpretation and modelling of potential field data in order to better determine the architecture at depth and better constrain the tectonic evolution of the basin. Our study raises new evidence of the strong link between the location of evaporitic diapir and the development of normal faults affecting the basement during the basin formation. These normal faults were subsequently reactivated during the Delamerian Orogeny, and still remain the main structures controlling the present-day deformation of the Flinders.
Paleoproterozoic terrane boundaries in the unexposed Northern Gawler Craton, Maria Region: new insights from a geophysical perspective Graham Baines\ David Giles^ Peter Betts^ Guillaume Backe^ ^ Centre for Mineral Exploration Under Cover, School of Earth and Environmental Sciences, University of Adelaide, South Australia, 5005 (graham. baines@adelaide. edu. au) School ofGeosciences, Monash University The geometry at depth of the unexposed basement of the northern Gawler Craton is poorly constrained yet its crustal architecture is of primary importance for models of continental growth during the amalgamation of Proterozoic Australia. Unfortunately, with less than 1% of basement exposed, the northern Gawler Craton is almost completely covered by Neoproterozoic and younger sedimentary rocks which have so far inhibited our understanding of the tectonic evolution of this area. Here, we focus on the basement architecture in the Maria region of the northernmost Gawler Craton. We use geophysical techniques and apply a top-down approach to penetrate the cover and determine the structure of the unexposed basement rocks. We use superficial geology, borehole data and seismic reflection profiles to determine the structure of overlying cover sequences and to constrain the role of basement structures in later intra-cratonic orogenies. We measured the petrophysical properties of samples, representing the whole sedimentary cover as well as the basement, along selected drillcores in the area of study. These data were used to remove the effect of the cover
from gravity and magnetic data, therefore highlighting basement structures. The architecture of the basement is then determined by combining Euler deconvolution along with forward and inverse modelling techniques. Our analysis shows that a broad magnetic anomaly observed over the Ammaroodinna Ridge is primarily due to shoaling of the basement rather than a change in its petrophysical properties, while the Middle Bore Fauh represents a major Paleoproterozoic terrane boundary that juxtaposes high density mafic rocks against metasediments. The basement structures revealed for the first time by our modelling approach enabled us to constrain the geological processes responsible for the growth and evolution of the northern terranes of the Gawler Craton and their role in the amalgamation of Australia during the Proterozoic.
P-T-X Conditions of Fluids in the Sunrise Dam Gold Deposit, Western Australia: Implications for the Interplay between Deformation and Fluids in Orogenic Gold Systems T. Baker^ T. Blenkinsop^ J. McLellan^ J. Cleverley^, and M. Nugus"^. ^EGRU, James Cook University, Townsville, Queensland (thaker@soverei2m71etalsxom.au: thomas. blenkinsop @ jcu. edu. au: John, mclellan @jcu. edu. au) ^CSIRO, Perth, Western Australia (james.cleverley@csiro.au) "^Sunrise Dam Gold Mine, AngloGold Ashanti Ltd (MNugus @AngloGoldAshanti. com. au) The formation of orogenic gold deposits is generally described as a complex interplay between deformation, permeability, rock strength and hydrothermal fluid pressure. Despite it being widely known that orogenic gold deposits form from low salinity, carbon dioxide-bearing fluids, the importance of this fluid composition in the context of the physical processes of deformation and fluid behaviour is commonly overlooked. In this study we combined fluid inclusion research with structural and numerical modeling in order to link these processes in the world class (10 MOz.) Late Archean Sunrise Dam gold deposit. The Sunrise Dam gold deposit is hosted within a complex structural environment. Several major moderately dipping NW shear zones formed during Di and host significant orebodies, however, the bulk of mineralization formed during D3 and D4. D3 is characterized by thrusting and sinistral shearing particularly in steeply dipping mineralized structures. D4 formed dextral faults producing steeply dipping stockwork vein systems. Numerical models suggest that high pore continued next page.. Australian Earth Sciences Convention 2008
47
48 ABSTRACTS alphabetfcaliy by surname of presenting author
fluid pressures are a pre-requisite for significant deformation at Sunrise Dam. Early low salinity CO2H2O fluid inclusions record high fluid pressures (300 MPa at 350°C) whereas later COs-rich fluid inclusions record much lower pressures (130MPa at 350^C). Reconstruction of P-T-X conditions suggest that the CO2-H2O fluid was initially trapped in the one phase field but may have undergone phase separation due to exhumation at lithostatic pore fluid pressures. The resulting phase changes may have initiated failure through possible volume expansion of fluid and changing physical wetting characteristics. The subsequent failure induced decompression may have resulted in the production of significant volumes of C02-rich fluids that coincided with the main period of gold deposition.
The auto-regressive model (ARM) approach to denoisING moroccan resistivity data phosphate "disturbances" map Saad Bakkali^ ^ Earth Sciences Department, Faculty of Sciences & Techniques, Tangier, Morocco saad. bakkali @ gmail com Several methods are currently used to optimize edges and contours of geophysical data maps. A resistivity map was expected to allow the electrical resistivity signal to be imaged in 2D in Moroccan resistivity survey in the mining domain. Anomalous zones of phosphate deposit "disturbances" correspond to resistivity anomalies. We propose a new method for white noise reduction of Moroccan phosphate disturbances map of resistivity data based on the auto-regressive model (ARM) approach. The effectiveness of our approach for successfully detecting and reducing white noise has been used much success in the analysis of stationary geophysical data. The ARM method is an efficient tool in the interpretation of geophysical potential field data particulary suitable in denoising, filtering and analyzing resistivity data singularities. The ARM filtering approach applied to modeling surface phosphate "disturbances" was found to be consistently useful. Key words : resistivity, Schlumberger, phosphate, auto-regressive, model, filtering, Morocco.
Australian Earth Sciences Convention 2008
Dryland saUnity and geodiversity on the Southern Tablelands of NSW: the use of the EM technique for mapping and management? Glen R. Bann\ John B. Field^ and Emlyn R. Williams^ ^Fenner School Environment and Society & CRC LEME, Australian National University, Canberra, 0200 ^ Statistics Consulting Unit, Australian National University, Canberra. 0200 Dryland salinity is a major concern on the Southern Tablelands of NSW (STNSW). Considerable research, remediation and mitigation has been undertaken on the topic, with the Electromagnetic Induction technique (EM) being promoted as a preferred tool for planning and undertaking such activities. The present research includes an investigation of the applicability of the EM technique to map and/or monitor dryland salinity outbreaks in upland landscapes, specifically the EM38 and EM31 Geonics hand held instruments, which are also widely used mounted on motor bikes. Research sites were restricted to relatively undisturbed areas on the STNSW, containing box/gum grassy woodlands, to reduce the compounding and confounding effects of intensive management practices. Lithology was restricted to two types within the Lachlan Fold Belt, Ordovician deep marine sediments and Silurian felsic volcanic deposits and associated marine sediments. EM measurements were taken along transects at 10 sites during autumn and spring of 2005. A number of other biotic and abiotic measurements were also taken, including soil EC, pH and evaporation indicators. Results indicate that as the EM measurements increase with depth (i.e. EM38 to EM31), EC and other related salinity measurements show less of a relationship with the EM readings. The EM readings for both instruments frequendy showed large variation over small distances, often within a few metres. The EM measurements increased from autumn to spring following considerable rainfall and are generally higher on the Silurian lithology. Soil EC measurements indicate that the high salt concentrations are generally at the surface, and concentrations vary considerably spatially and temporally. As EM readings are a function of multiple factors, including soil moisture, clays and ferrous minerals content and salt, which are all heterogeneous spatially and temporally, ground truthing is necessary, and at the same time as the EM surveys are performed. This is often impractical, laborious and expensive. We therefore suggest that mapping, monitoring and management should be focused on surveys of soil surface factors, such as evidence of evaporation, organic matter content and degradation effects due to intensive stock grazing.
ABSTRACTS alphabetically by surname of presenting author
^Living Geodiversity' - simplified geology maps with linked eco-geo field trips for school and community education
Dryland salinity and woodland biota in a f a r m i n g ' south eastern Australia: endemic flora and fauna to the rescue!
Glen R. Bann\ Rachel A. Nanson^ and John C. Rowntree^
Glen R. B m n \ John B. Field^ and Emlyn R. Williams^
1. Fenner School Environment and Society and CRC LEME, Australian National University, Canberra. 0200 (glen, bann @ anu. edu. au) 2. Australian School of Petroleum, Adelaide University, Adelaide 3. Hunter Minerals Pty Ltd, Kangaroo Valley 2577
^Fenner School Environment and Society & CRC LEME, Australian National University, Canberra, 0200 ^ Statistics Consulting Unit, Australian National University, Canberra. 0200
The Sydney Basin is renowned for providing numerous examples of excellent outcrops for the teaching of geology and the earth sciences. The same can be said for the regions diverse ecology, particularly vegetation communities. Despite the current mineral resources boom (or 'elevated plateau'), geology departments around the country have decreased in number during the past decade and geology is generally not offered as a school subject for the Higher School Certificate. This project, 'Living Geodiversity', is designed to provide an educational tool for the teaching of geology and earth surface processes (geodiversity) and associated ecology. Field trips are based upon 1:100,000 simplified geological maps; user friendly, colour coded maps with stratigraphic sections and text. Units are grouped into Geological Periods, with main roads, towns and rivers and other easily recognized landmarks identified. The field trips contain guide notes with numerous photos and figures, with stops clearly labeled on each map. The stops are designed to cover a variety of interesting and relevant geological and related ecological features, with a primary objective to capture the interest of the participants, to gain an increased appreciation of the environment and thereby encourage them to pursue careers in science. The field trips can be individually tailored to suit the specific interest, education level or duration. The prototype map and field trips are being trialed in local secondary colleges with the intention of utilising teacher and student feedback to improve the product. It is anticipated that the program will be trialed in more schools and colleges and ultimately, be incorporated into school curriculums.
Dryland salinity is reported to be a major threat to terrestrial biodiversity in many parts of southern Australia however, very little quantitative research has been undertaken that links dryland salinity with adverse effects to terrestrial biota. The principles and mechanisms are poorly understood or explained. This issue requires urgent attention, particularly considering the fact that increasing temperatures (and evaporation rates) are predicted in the future, and these will likely cause compounding problems for land management and biodiversity conservation. The present research investigates relationships and trends between abiotic and biotic metrics taken at 10 salinised and non-salinised sites over three years in box/gum grassy woodlands of south-eastern Austraha. Biotic surveys included site flora and fauna identification, scat analyses, pitfall trapping, log disc habitat measures, collections from buried toilet rolls soaked in 'termite liquor', photosynthesis efficiency in eucalypt leaves and bulk soil microbial respiration. Results indicate that many endemic fauna and flora species do appear to flourish at salinised and degraded sites; ants, spiders, wasps, worms, termites, centipedes, frogs and lizards tolerate increased and fluctuating salinity levels. No relationship was found with increasing sahnity on pitfall trap or log disc habitat numbers, or with termite presence. Mammals such as brush-tailed possums, swamp wallabies and eastern grey kangaroos are common at all sites. Foxes are present at all sites and are common across the entire study region. Many endemic grass and tree species appear to be relatively salt tolerant, during all stages of their hfe cycles. Most are also drought tolerant. This is to be expected, as Australia is one of the saltiest and driest places on earth. It is problematical to directly link increased soil salinity as such, with ecological stress, consequent on global warming, as many other factors are involved and may be more significant. These include the compounding adverse effects of increased soil and vegetation degradation due to intensive stock grazing and fox predation.
Australian Earth Sciences Convention 2008
49
50
ABSTRACTS alphabetically by surname of presenting author
Mineral Precipitation in Porous Media: Laboratory Diffusion Experiments as Analogues for Concretion Formation in Utah and on Mars. Laura M. Barged John Petmska^ Sally Potter ^ June Cho"^, Marjorie Chan^, Ken Nealson^ ^ University of Southern California, Dept. of Earth Sciences, 3651 Trousdale Parkway, Los Angeles, CA 90089 (barge@usc.edu, knealson@usc.edu) ^ University of Southern California, Dept. of Biological Sciences, 1050 Child's Way, Los Angeles, CA 90089 (petruska@usc.edu) ^ University of Utah, Dept. of Geology and Geophysics, 135 S. 1460 E, Room 719, Salt Lake City, UT, 84112 (marjorie.chan@utah.edu, sally.potter@usc. edu) University of Southern California, Dept. of Electrical Engineering, 3740 McClintock Ave, Los Angeles, CA 90089 (jeeuncho@usc.edu) We present results of laboratory gel diffusion experiments designed to simulate the precipitation of iron minerals in natural systems. Liesegang bands and crystals of various iron minerals were formed in aqueous gels, "mini-concretions" of mineral precipitate were formed in both sand and a sand/agarose mixture, and the formation of hollow mineral spheres was observed in gel precipitation experiments where organics were introduced. These mineral structures are analogous to concretion forms observed in the Navajo Sandstone region of Utah, which have been suggested as terrestrial analogs for the "blueberry" hematite concretions on Mars. Iron mineral precipitates occur in many forms in the Navajo Sandstone, including "mini-concretions" (solid concretions 1-2 mm in diameter), "rind-like" concretions (hollow spheres of hematite several cm in diameter, surrounding a region of sandstone), and Liesegang banding (banded patterns that form at reaction fronts through diffusion of ions from one reservoir to another). On Mars only miniconcretions have been observed; Liesegang bands or large rind-like concretions do not appear to be present. The varying conditions that give rise to each of these mineral structures in the laboratory indicate that the different types of iron precipitates found in the Utah and Martian environments may be diagnostic of the diffusion medium, presence of organics, and characteristics of fluid in that region.
Exploration Science Andy Bamicoat^ ^ pmd'^CRC, Geoscience Australia, GPO Box 378, Canberra, ACT 2601 (andrew. barnicoat@ga.gov. au) The concept of mineral systems ("all geological factors that control the generation and preservation of mineral deposits") was formally introduced over 10 years ago, and has provided a background to much Australian work on ore deposits. The AGCRC and the pmd*CRC has encapsulated the concept of mineral systems in 5 Questions about a mineral system: 1. What are the geodynamic and P-T histories of the mineral system? 2. What is its architecture? 3. What fluid reservoirs were involved? 4. What were the fluid pathways and driving forces? 5. What processes were responsible for metal and sulphur transport and deposition?. These questions ensure that the context of mineralisation is fully assessed and drive the consideration of features across scale. Such an analysis is, however, essentially empirical in nature. Most ore deposits arise as a result of the flow of a fluid coupled with a change in the capacity of that fluid to transport element(s) of economic value. It is possible to derive a relationship describing the critical factors necessary for the formation of hydrothermal ore bodies, and this means that the critical physico-chemical parameters responsible for ore formation can be identified. These parameters can be mapped into the 5 Questions to give a rigorous underpinning to the analysis of mineral systems. The answers to the 5 Questions, if they are to be relevant to exploration, need to focus both on the fundamental aspects of the physics and chemistry of the system that underpin them, and need to be expressed in terms of mappable or at least detectable features. Information can be drawn from the questions that are most applicable to the scale at which exploration decisions are being taken. This link between fundamental scientific understanding, the mappable expression of the key parameters and exploration forms Exploration Science.
Depositional age and provenance of the Palaeoproterozoic Hutchison Group, southern Gawler Craton, South Australia Karin Barovich^ Michael Szpunar^'^, Martin Hand\ Liz Jagodzinski^ ^Continental Evolution Research Group, School of Earth & Environmental Sciences, University of Adelaide, Adelaide SA 5005
Australian Earth Sciences Convention 2008
ABSTRACTS aiphabetfcally by sorname of presenting author
Geological Survey Branch, Minerals & Energy Resources Division, PIRSA, GPO Box 1671 Adelaide SA 5001 The late Palaeoproterozoic Hutchison Group, Gawler Craton, South Austraha, holds a substantial record of the early tectonic evolution of the Southern Australian Proterozoic (SAP). However, there is still debate about its depositional age, and its provenance is largely unconstrained. The Hutchison Group is historically interpreted to be deposited between ~1960Ma and ~1850Ma in an east deepening basin. Sedimentary fill is thought to be sourced from the west, predominantly from the ca 2500 Ma and ca 2000 Ma basement which the basal unit unconformably overUes. Psammopelites from the lowermost units across the southern Gawler Craton contain ca 2500 Ma and 2000 Ma detrital zircons and have evolved Nd isotope signatures at 1850 Ma (8Nd around -10) consistent with derivation from upper Gawler Craton crust. In contrast, overlying units in the southeast also contain ca 1850 Ma and 1790 Ma detrital zircons. These units have significantly more juvenile 8Nd(1700Ma) values around -2 and geochemical affinities with a more mafic source than that for basal psammopelites. The combined geochronological and geochemical data indicate: 1) There are complications in the depositional age of units in the Hutchison Group. The overlying packages are as young as ca 1790 Ma, 60 Ma younger than the currently understood depositional age of the Hutchison Group; 2) Correlations from south to north need to be re-examined; 3) The younger sediments were sourcing terrains not currently identified on the proximal Gawler Craton.
Nd isotopes and their utility in crustal evolution studies in Proterozoic Australia Karin M. Barovich Martin Hand, Benjamin Wade, Justin L. Payne Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, Adelaide SA 5005 Nd isotopes have proved to be a remarkable tool for the study of continental crustal evolution. Isotopic studies of igneous and sedimentary rocks can allow distinction between periods of crustal growth and crustal re-working. Based largely on Nd isotope data, it is estimated that anywhere from 70 to 100% of the continental crust was formed by the Palaeoproterozoic. Terranes with positive 8Nd values are most abundant, supporting a high rate of crustal growth in the Palaeoproterozoic. There is little argument among workers that the North Atlantic
crustal region in particular was an area of major plate subduction activity, operating, at least in a gross sense, in a style comparable to modern day plate tectonics. Proterozoic crustal evolution in Australia, on the other hand, was historically interpreted in an essentially non-uniformitarian manner. In this theory, intracontinental rifting of Achaean crust, not plate margin activity, caused Proterozoic tectonic events. This interpretation m s based less on Nd isotope data, which was not widely available at the time, and more so on traditional geochemical and structural features. In Australia, an examination of initial SNd data shows variation over a large range, and values tend to be only slightly positive to quite negative. In fact, values close to the depleted mantle curve in Palaeoproterozoic Australia are rare. As the areal extent of Palaeoproterozoic terranes in Australia is of the same order as for North America, this difference in Nd isotopic crustal signature is significant. Despite recent arguments for an uniformitarian model for the Palaeoproterozoic evolution of the Australian crust, there is no doubt that there are drastic differences in the evolution of Proterozoic Australian crust when compared to Proterozoic North Atlantic crust. Any models that attempt to explain the Palaeoproterozoic crustal evolution of Australia must account for its relative paucity of juvenile crust.
Gauging reasons for enrolment in an entry level university geology course: Results of student surveys from 20022007 Karin M. Barovich Geology and Geophysics, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005 (karin. barovich@adelaide. edu. au) Bachelor of Science students commencing at the University of Adelaide are able to choose from up to fourteen Level I science courses in semester one. These choices include six areas of full-year study. Academic advice in making choices is variable, as enrolment may be done online. From 2002 through 2007 the University of Adelaide Geology & Geophysics Discipline has used a variety of methods to inform students about geology and our 1st year offerings, including visits to schools, pre-enrolment lectures, web pages and building displays. Over that time I have conducted a voluntary survey in the first week of Level I geology with two purposes: to examine the influence of outreach and marketing methods and to evaluate a range of possibilities for student choice of a geology course. continued next page.. Australian Earth Sciences Convention 2008
51
52 ABSTRACTS alphabetically by surname of presenting author While the class size has grown from 65 to around 220 from 2002-2007, overall the influences of outreach/marketing methods and reasons for choosing geology have not shown any particular trends. Two encouraging trends: 1) an increase in students who indicated their school advised geology as a possible university subject (7% to 18%); and 2) no change in the number who chose geology because they lacked prerequisites for other subjects. Two discouraging trends: 1) the percentage of students who chose geology because they were interested in it before enrolment has not increased; 2) the drop in students who chose geology because they like outdoor activities. The results suggest that: 1) we must continue to maintain our current level of all outreach/marketing activities in order to keep a viable critical mass of potential majors into 2nd and 3rd year; and 2) the current mining boom and resultant buoyant career options in earth sciences is not being fully realis ed by the students themselves, although school advisers are slowly gaining awareness.
Extension in lower crustal granulite fades mafic orthogneisses of the Biranup Complex (Albany-Fraser Orogen), Bremer Bay, Western Australia
in most of the field area, although locally early isoclinal folds of centimeter wide melt bands with axial planar migmatitic fabric have been observed. These rocks record an early phase of simultaneous extension in two orthogonal directions, NE-SW and NW-SE, which resulted in the formation of centimeter scale square boudins of mafic restitic layers parallel to the main migmatitic fabric. This was followed by folding, with the formation of kilometer scale, N-NW verging overturned folds, and associated outcrop scale (centimeters to a few meters) folds, which are upright to overturned, isoclinal to open, and usually double verging (N-NW or S-SE). Folding was followed by renewed coeval NE-SW and NW-SE extension that produced intermediate (less than a meter to a few meters) to large (decameter) scale boudins of the migmatitic fabric. Melting took place during all stages of deformation, and granitic melts segregated in boudin necks of intermediate N E SW and NW-SE boudins of the migmatitic fabric have given SHRIMP l>Pb zircon ages of 1187±5 Ma and 1178±4 Ma respectively.
Geology and Mineralization of the Rocklands Copper Deposits, Cloncurry District, North West Queensland. Simon D. Beams ^ ^ Terra Search Pty Ltd
Miriam Barquero-Molina^ Sharon M o s h e r ^ Catherine V. Spaggiari^, S i m o n B o d o r k o ^ ^ Department of Geological Sciences, The University of Texas at Austin, 1 University Station CI 100, Austin, TX78712, USA fmiriafnlO(d)maiLutexas.echi) (niosherCchmaii utexas. edu) ^ Geological Survey of Western Australia, 100 Plain Street, East Perth, WA, 6004, Australia (Catherine. spa22iari(a),doir, wa. gov, au) ^ Geoscience Australia, GPO Box 378, Canberra ACT2601, Australia (Simon.BodorkosCod.w.gov.au) The Albany-Fraser Orogen (AFO) is currently interpreted to be the result of collision between the Yilgarn Craton of southwestern Australia and the Mawson Craton of Eastern Antarctica during Stage I of the orogeny (c. 1345-1260 Ma). Structures observed in mafic granulites from the Bremer Bay area suggest pervasive lower crustal extension at c. 1180 Ma, based on SHRIMP U-Pb zircon geochronology of melts generated during deformation. This age coincides with Stage II (12101140 Ma), a period of NW-directed contraction in current tectonic models for the AFO. Granulite facies rocks in the Bremer Bay area are dominantly stromatic migmatites with lithologies that include tonalitic, granodioritic and dioritic orthogneisses. A prevalent fabric is defined by alternating leucosomes and melanosomes, and it is parallel to the main compositional layering. Formation of this fabric is the earliest event recorded
In April, 2006 Cudeco Limited intersected significant copper mineralization at their solely owned Rocklands project, 15 km west of Cloncurry in the Eastem Succession of the Proterozoic Mt Isa Inlier, north west Queensland. An extensive geological data set has been built up since then with surface mapping and an intensive drilling program involving over 90,000m of mostly reverse circulation percussion and subordinate diamond drill core. Other data sets include ground and airbome magnetics , radiometrics, IP, surface geochemistry . This paper reports the current geological understanding of the Rocklands copper depsits. Copper mineralization over the Rocklands project area is hosted in a series of sub parallel ,west north west trending, linear zones. Las Minerale , La Meridien and Rocklands South are the most prominent mineralized structures identified to date. The mineraHzed lodes occur within a Proterozoic metamorphosed sedimentary sequence of siltstone, quartz magnetite sandstone, limestone and calc silicates of Proterozoic age, assigned to the Overhang Jaspilite unit within the nose of the Duck Creek Anticline. Medium grained, intrusive dolerite is very prominent in the area and appears generally conformable with the sediments. At Las Minerale primary chalcopyrite mineralization occurs within a steeply dipping , throughgoing, west north west trending, linear, structure that cuts the dipping sediment-dolerite package at a high angle. The structure represents a mineralized channelway or "plumbing system" containing a host of lithologies, including vein material and hydrothermal breccias, together with silvers of apparently in situ shattered and altered wall rock. The mineralized vein and breccia infill is dominantly
ABSTRACTS 53 alphabetically by surname of presenting author
calcite-quartz-actinolite-magnetite-sulphide. Both monomict clast supported and polymict matrix supported breccias occur. Primary copper mineraHzation is evident as coarse splashes of irregular chalcopyrite with coarse well formed pyrite, particularly associated with calcite ,quartz, actinolite vein and breccia infill. Total sulphide content within the mineralized Las Minerale structure is variable from 1-2% up to 10-20%. Alteration associated with the mineralization is a moderate to high temperature assemblage of biotite, actinolitic amphibole, red feldspar (probably both potassium feldspar and albite), magnetite, calcite, silica. Base of oxidation in unmineralized rocks within the project area is a relatively shallow 10-20m. However, oxidation of the sulphidic mineralized structures at Las Minerale and Double Oxide have generated acid fluids which have
resulted in leaching, deep oxidation and supergene
enrichment of copper. Within the oxidized zone , copper has been leached from near surface areas and re -deposited as coarse nuggets of native copper. Copper carried in solution to below the base of oxidation, replaces existing sulphides with the copper enriched mineral chalcocite. This leaching and reprecipitation is responsible for some of the spectacular high copper grades. Oxidation at Las Minerale has been observed at vertical depths in excess of 100m. Coarse nuggets of native copper are particularly associated with the oxidized versions of quartz rich breccia characterized by abundant green clay of probable supergene origin. Cudeco's exploration to date has shown that the Las Minerale and Double Oxide structures contain ore grade and thickness copper mineralization over strike lengths of hundreds of metres. Within the Cudeco tenements there are several other promising sub parallel linear breccia and alteration zones, all of which are currently been actively drill tested.
Geothermal Systems Analysis—A Risk Based Approach to Exploring for Geothermal Resources Dr Graeme Beardsmore^ 'Hot Dry Rocks Pty Ltd, South Yarra, Victoria, Australia Exploration for geothermal resources has historically been approached in an ad hoc manner in the vicinity of surface manifestations such as hot springs. In Australia, however, most exploration is focusing on conductive thermal areas not associated with obvious surface indicators. A commercial geothermal system in these areas requires a fortuitous configuration of four basic parameters: heat flow, thermal insulation, a reservoir (or potential for engineering a reservoir), and available water. Geothermal Systems Analysis is a structure for looking at the available evidence for each of these parameters and assessing the risk of each. This quantifies the overall exploration risk and focuses attention and resources on those parameters that are least constrained, prior to expensive validation drilling.
Tectonics, Plumes and Super continents: The Energy Link Graham Begg^^^ ' Minerals Targeting International PL, Suite 26, 17 Prowse St. West Perth, WA 6005, Australia ^ GEMOC, Dept of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia How does the Earth work? What drives tectonics? Are plumes part of a larger pattern? Why do supercontinents form, how and why do they break up, and can they reform in the same place? Why do supercontinents seem to be periodic (-800 Myrs) and when was the first one (there have been at least four)? These questions encapsulate some of the most fundamental questions in Earth Science. The key is the ultimate driver of all Earth systems, the cooling of the planet via heat (energy) loss to space, and how Earth accommodates this loss. The Earth contains two great discontinuities, the free air surface and the Core Mantle Boundary (CMB). Across the former, the transition to atmospheric P and T conditions engenders the development of a rigid, cool oceanic lithosphere. Across the CMB is a massive change in both rheology (from a liquid Outer Core to a solid Lower Mantle) and temperature (perhaps as much as 1500°C). Between the lithosphere and the CMB is a viscous mantle which has a heterogeneous density structure and is capable of mass transfer (e.g. convection). The processes of plate tectonics and plume dynamics seek to minimize potential energy at the two boundary layers, however, this action at one boundary creates potential energy at the other and vice versa. Thus the planet is in a constant state of disequilibrium. Every 800 Myrs the plate tectonic process creates supercontinents overlying slab graveyards at the CMB. Ensuing "plume blooms" disperse the graveyard, creating superplumes and supers wells that catastrophically reset spatial density patterns in the mantle (as seen in the geoid). The resultant mantle upwelling and gravitational potential energy encourage plate tectonics to disperse the supercontinent, thereby restarting the cycle. These processes result in predictable patterns in the mantle and crust, including the formation of nickel sulphide ore deposits.
continued next page... Australian Earth Sciences Convention 2008
54 ABSTRACTS alphabeticalfy by surname of presenting author
What Are In-situ Gold Resources Worth? An Empirical Study Jonathan Bell\ Pietro Guj^ ^ Snowden Mining Industry Consultants Pty Ltd - PO Box 77 West Perth, Western Australia, 6872 (jbell @ snowdengroup. com) ^ Curtin University of Technology (Western Australian School of Mines) - GPO Box U 1987, Perth, Western Australia, 6845 (p.guj@curtin.edu.au) The sale prices of 201 gold mining projects throughout the world reflect the expectation that, at some stage, they may support potentially profitable mining operations and the magnitude of their future cash flows. The sales price is largely a function of the size (Moz) and grade (g/t Au) of the resource, which affect the type and scale of a possible operation and its Hkely capital and operating costs, and of the level of country risk (measured by a combined OECD - Frazer Institute index). The dynamic relationship between these parameters was used in a block-model to predict prices for future transactions in various geopolitical environments given any size and grade combination. This analysis suggests that in safe and prospective environments the market attributes preferential value to size and, conversely, higher grades are preferred in risky or un-prospective environments. In medium-risk environments preferences are polarised between high-grade or very large resources, with medium-size/grade resources being relatively cheap. The block-model approach adopted in this study has the potential to inject some comparability and objectivity into the currendy somewhat arbitrary apphcation of 'rule-of-thumb' in determining transaction prices for in-situ resources. In theory, in liquid markets, given the size, grade and price of a transaction, the block-model approach could be used to derive the sovereign risk discount implicit in the market.
TerraneChron approach to the crustal evolution studies and implications for continental growth Elena Belousova^ William L. Griffin^ Suzanne Y. O'Reilly ^GEMOC National Key Centre, Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW2109 (ebelouso@els.mq.edu.au) TerraneChron® is GEMOC's unique methodology specifically developed to study the evolution and growth of the continental crust through time. It is based on the integrated in situ analysis of zircons for U-Pb and Hf isotopic
Australian Earth Sciences Convention 2008
composition using laser-ablation microprobe techniques. The UPb analyses provide rapid and cost-effective age determinations, while the Hfisotopic data give information on the source of the magmatic parent rock for each zircon; they tell whether the relevant tectonic event was accompanied by young mantle-derived magmatic input, if only pre -existing crust was involved, or if the event represents a combination of these processes. The methodology is typically applied to zircons from drainage samples judiciously collected within a defined catchment that sample areas of the crust formed in different tectonic settings. Thus, the TerraneChron® approach allows the evaluation of how much new crust was formed, and how much older crust was recycled, at different stages of Earth's history. The U-Pb age data collected for over 5000 zircons worldwide would support a "Punctuated Growth" model if treated on its own. However, Hfisotopic data suggest that the juvenile contribution represents only a small proportion of those magmatic episodes. The data available so far imply that juvenile additions are not especially significant, and that recycling of pre-existing crust has been the major mechanism of crustal generation, especially after ca 3.0 Ga. Modelling of the ages of the recycled components emphasises the repeated reworking of Archean components, supporting an "Early Growth" model. The data were collected mainly from Archean/Proterozoic cratonic areas with thick continental crust and deep lithosphericmantle roots. Continental rift zones and convergentmargin environments, where a larger juvenile material input would be expected, are certainly under-represented at this stage. However, the data illustrate the power of the method for testing models of crustal growth rates.
Advances in magmatic Ni-Cu-PGE exploration geoscience: challenging dogma and developing new ideas for an evolving search space. S.W.Beresford^^ T.C.McCuaig\ Fiorentini^
M.L.
^ Centre for Exploration Targeting, University of Western Australia (sberesfo@cylleneMwa.edu.au) ^ newgenco PtyLtd, Western Australia Challenging the current geological understanding is an essential component of mineral exploration, especially in the maturing search space. How can we apply new ideas or technologies to this ground or project, is there a window of opportunity within the previous work? Competitive advantage in both grassroots exploration and project acquisition/evaluation lies in high quality geoscientists who develop multiple hypotheses and challenge existing dogma. This approach contrasts with the modern academic mindset which values and
ABSTRACTS 55 alphabetically by surname of presenting author
rewards reinforcement. We review recent advances in the predictive and detective science of magmatic Ni-Cu-PGE exploration, as seen through the eyes of recent discoveries. These discoveries highlight the continuum/diversity of deposit styles and their geochemical and geochemical expressions. Insights from these discoveries challenge a number of commonly held views on magmatic Ni-Cu-PGE deposits and thus identify/demand avenues for further work.
A New Type of Basaltic Eucrite: Clues to Early Differentiation of Igneous Asteroids Katherine R. Bermingham^ Marc D. Norman\ Andrew G. Christy^ Richard Arculus^ ^ Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia Eucrites are igneous meteorites thought to originate from asteroid 4Vesta, one of the few asteroids with a basaltic surface. The aim of this project was to evaluate the petrology and geochemistry of twelve new eucrite samples to better understand their petrogenesis and igneous processes occurring during the earliest stages of planetary assembly. Textures and mineral compositions were determined using optical and electron microscopy. Major element compositions of whole rock powders were measured using XRF and energy-dispersive SEM analysis of Li-borate fused glasses. Whole rock trace element compositions were also measured on the Li-borate glasses using laser-ablation ICPMS. All of these eucrites have basaltic textures but the range of grain sizes indicates variable cooling rates. Some samples erupted as surface flows whereas others were emplaced at relatively shallow depths (<5 km) based on pyroxene exsolution lamellae thickness. Major element compositions classify all samples as non-cumulate eucrites, and cluster near an experimentally-determined peritectic (Stolper 1977, GCA). Trace element compositions show more variability with Ce concentrations ranging from 2.4 to 16.9 ppm, and REE patterns ranging from LREE-enriched with negative Eu anomalies (Group 1) to LREE-depleted with positive Eu anomalies (Group 2). The LREE-depleted Group 2 samples appear to represent a new type of noncumulate basaltic eucrite that has not been recognized previously. The two leading models for the petrogenesis of basaltic eucrites are (1) variable degrees of partial melting of a primitive body; and (2) progressive crystallisation of a magma ocean. The positive correlation of Sr/Nd with Eu/Eu* in our samples suggests involvement of plagioclase, but the small
range of major element compositions rules out accumulation or fractional crystallization from a common parental magma. Preliminary modeling of the Group 2 trace element compositions suggests an origin by melting of a source region that had been enriched in plagioclase but additional work is underway.
Proterozoic accretionary processes of Australia and comparisons with Laurentia. Peter Betts^ David Giles^ ^ School of Geosciences, Monash University, Clayton 3800. (Peter,Betts(cd.sci. monash. echi. aid. 2 Centre of Exploration Undercover, University of Adelaide 5001 (David.Giles@adelaide.edu.au) There is strong evidence for subduction related tectonic processes driving the tectonic evolution of the Australian continent during the Proterozoic. There is increasing evidence that juvenile arc-related magmatism and orogenic systems at the first order appear to form relatively linear belts, with local complexities. Interpretations that invoke the plate tectonic paradigm need to consider numerous observations within the Proterozoic geology of Australia, vhich are not consistent with tectonic processes that we observe in modern tectonic environments. The Proterozoic of Australia is characterised by elevated heat flow, and mobile belts are characterised by predominantly high temperature metamorphism Granite suites are evolved and have model ages that are several hundreds of millions years older than their emplacement age. Juvenile magmas are relatively rare, although there is an increase in juvenile igneous suites at the Palaeo- to Mesoproterozoic boundary. The style of accretion at the plate margins of Australia and Laurentia is somewhat different, with Laurentia characterised by accretion of dominantly juvenile arc terranes. This difference could be attributed to the relative position of high heat production rocks with respect to the plate margin. In Australia, Dcks with elevated heat flux are located proximal to the plate margin, whereas Laurentian rocks with elevated heat flux are located deep within the continental interior. During roll-back events Australia's lithosphere would therefore have become highly attenuated through ductile extension and large fragments of continental crust would have been rifted from the continent. Accretion would have resulted in the re-amalgamation of pre-existing continental lithosphere not dissimilar to the lithosphere in the overriding plate. Subduction roll back adjacent to the cold and rigid Laurentian margin had a relatively little impact on the overriding plate; oceanic back arc basins were created with relatively small fragments of continental lithosphere. Continental growth occurred via accretion of arc and oceanic back-arc rocks. Australian Earth Sciences Convention 2008
56
ABSTRACTS alpliafoetlcally by syrname of presentlrig aythor
Evidence for a Mesoproterozoic Hotspot Track in Eastern & Central Australia Peter Betts\ David Giles^, Bruce Schaefer^ Geordie Mark^ ^ School of Geosciences, Monash University, Clayton 3800. (Peter.Betts@sci.monash.edu.au) ^ Centre for Mineral Exploration Under Cover, School of Earth and Environmental Sciences, University of Adelaide, South Australia, 5005 Mesoproterozoic A-type magmatic rocks in the Gawler Craton, Curnamona Province and eastern Mount Isa Inlier, form a paleo-curvilinear magmatic belt in reconstructed plate orientations. The oldest magmas occur in the Gawler Craton (Hiltaba Granite Suite: -1600-1575 Ma) and the youngest occur in the Mount Isa Inlier (Williams-Naraku Batholiths: -1545-1500 Ma). The belt is interpreted as a segment of a hotspot track that evolved between -1600-1500 Ma. This hotspot track is coincident with the palaeomagnetic-defined quasilinear motion of AustraHa between 1636 Ma and 1590 Ma, which suggests that Australia continued to migrate along the same path during the early Mesoproterozoic. Australia drifted to high latitudes at this time. An implication of this interpretation is that Australia and Laurentia may not have been fellow travellers leading to the formation of Rodinia. A hotspot model for Atype magmatism in Australia differs from geodynamic models for this style of magmatism on other continents such as those developed for Proterozoic A-type provinces in Laurentia and Baltica. This suggests that multiple geologic processes may be responsible for the genesis of Proterozoic A-type magmas.
A Comparative Gold Prospectivity Assessment of the Lake Victoria Greenstone Terrane, NW Tanzania and the Eastern Goldfields Province, Western Australia Frank P. Bierlein^, Ivo M.A. Vos
1,2
^ Resolute Mining (Tanzania) Ltd., PO Box 78486, Masaki, Dar es Salaam, Tanzania ^ Centre for Exploration Targeting, University of Western Australia, Crawley WA 6009, Australia Tanzania is host to a number of gold-rich regions, of which the Archaean Lake Victoria Greenstone Terrane (LVGT) is the most renowned. The LVGT alone hosts a number of world-class and major gold mines and deposits, including Geita (~14Moz), Bulyanhulu (-12Moz), North Mara (~5Moz), Golden Pride (-3Moz) and Buzwagi (~3Moz). Other gold fields in Tanzania include the Proterozoic Lupa and Mpanda Goldfields. Australian Earth Sciences Convention 2008
In our presentation we will review the current knowledge and understanding of tectonic settings, and principal controls on the development of gold deposits in the LVGT. Comparisons with Archaean and gold-rich terranes, such as the Eastern Goldfields Province (EGP) of the Yilgarn Craton in Western Australia, illustrate that marked similarities exist between these and the LVGT. However, the LVGT can be distinguished on the basis of a number of firstorder features, such as the absence of linear belts, major terrane-bounding sutures and granite/greenstone ratio. These features impact on the gold (and exploration) potential of the LVGT, and thus need to be better understood. Unlike for the high data density EGP, no reliable geochronological data exist for the timing of gold mineralization in the LVGT. It remains undetermined whether all gold deposits formed as a result of one event or if there a diachronous evolution and formation of gold deposits within the LVGT. Likewise, major uncertainty exists regarding the nature of tectonic processes that controlled the formation of gold deposits in the LVGT. Ongoing studies and collaborative research aim at enhancing the understanding of processes that led to the formation of gold deposits in the LVGT, and the tectonic setting in which they formed. The knowledge generated from these investigations will greatly assist in area selection and future exploration within the LVGT.
Challenges in Fault Modelling of Coal Seams Mark Biggs^ ^Coal Quality and Scheduling Superintendent, Anglo Coal (Dawson Management) Pty Limited Fault modelling in coal has evolved in recent times from thought processes in 2D to those in 3D. However, many practitioners modelling faults in coal seams have become mesmerised by the software. Faults aren't just green lines on the plan. Successful modelling requires a return to geological "first principles" and this starts with an understanding of the regional structural setting of the study area. Examination of old reports, plans, and field mapping notes by government geologists and University Honours students can provide important clues into fault styles, frequency, and spatial distribution. There are many sources for fault characterisation at a mine site or local level, such as: - Open cut and Underground exposures; - Borehole Dislocation (intersected); - Rapid Change of level between close-spaced boreholes; - Seismic interpretation; - Digitising off old plans; - Missing stratigraphic sections; - Photogeological interpretation; - Probalistic modelling/extrapolation; - Cross-Section Display;
ABSTRACTS alphabetically by surname of presenting author
- Seam Splitting and splay diagrams. Transferring known information about coal measure faulting into mine planning packages requires a transformation into dislocating, and often intersecting planes. There are many characteristics that define these planes such as: - Type; - Strike; - Dip; - Sense; - Height datum; - Era; - Extent; - Segments. Each is examined in the paper with several examples of the modelled fault and their field counterpart given. Modelling faults this way is an iterative process. Structure contour plots and perpendicular-to-strike cross-sections are frequently used to satisfy the commonly asked modelling questions, like: - What is the strike length? - What seams are affected? - What are the fault's throws? - At what height datum is the fault? Successful modelhng of faults has farreaching influence on mine planning and design, as there are always adverse imphcations for mining. Tools now exist to better achieve this objective but their application needs to be more systematic than current industry practice.
Benthic Foraminifera assemblages in the northern Spencer Gulf, South Australia further evidence for Holocene sea-level changes.
environmental distributions are known. Nubecularia lucifuga, Peneroplis planatus and Vertebralina striata commonly inhabit shallow, subtidal to intertidal, seagrass meadows. By comparison Massilina milletti is more abundant in deeper open gulf waters. In core SG #279, the combined maximum number of the three shallow water species occurs at a core depth of 102cm; thereafter numbers decline steadily upcore to a minimum at 40cm. This distribution upcore is interpreted as a proxy for water deepening, i.e. marine transgression. In contrast, Massilina milletti increases in abundance upcore, reaching its acme also at 40cm, providing further evidence of marine transgression. Thus, together these four species record the Holocene postglacial marine transgression and its culmination is signified by the sediments at a core depth of 40cm. Declining numbers of Massilina milletti from 40cm upcore signify subsequent marine regression. This regression has been attributed to both hydroisostatic and eustatic processes. The data from core SG #279 and their interpretations are in accord with published studies and further support the use of benthic foraminiferal assemblages as environmental proxies in palaeo-sea-level studies.
An Integrated Approach to Geological Screening for Sequestration Potential An Example from the Darling Basin, New South Wales Jane Blevin^ Lynn Pryer^ Tom Loutit\ Donna Cathro^ and Lisa Hall^
M. N. Binnie^ and J. H. Cann ^
^FrOG Tech Pty Ltd, PO Box 250, Deakin West ACT 2601(jblevin @frogtech. com. au)
^ University of South Australia, Mawson Lakes (Mary-Anne.Binnie@postgr ads. unisa. edu. au) ^ University of South Australia, Mawson Lakes (John. Cann@unisa. edu. au)
In 2006, the NSW Department of Primary Industry and a consortium of power generation companies commissioned FrOG Tech to undertake a reservoir prediction study of the Darhng Basin. The aim was to identify areas that have reservoir quality and seal potential at subsurface depths (>800m depth) appropriate for storage of CO2 in a supercritical state. A similar study of the Sydney Basin was commissioned by NSW DPI and a private energy company. Both basins are frontier and previous assessments faced major obstacles due to a lack of modern geological datasets. Previous screenings had concluded there was a low potential for storage in these basins mainly due to poor reservoir quality and injectivitiy issues. The first step in the new screening process was to build a regional tectonic and structural framework which would provide a geological context for fully understanding the sparse, but more detailed datasets. Using potential field datasets in the Darling Basin, massive Silurian granites were interpreted to underlie the present-day remnants of what was formerly a much larger foreland basin system. The
Spencer Gulf is an elongate, marine embayment on the southeastern coastline of South Australia. Northern waters are shallow, tidaldominated and normally subject to low wave energy. In situ bioclastic sedimentation occurs within extensive seagrass meadows and mangrove woodlands. Foraminiferal biofacies clearly define these prograding coastal environments. Vibrocore SG #279, taken from 8-10m water depth in northern Spencer Gulf, comprises 4m of Quaternary sediments. On lithological evidence, the uppermost 110cm is of Holocene age and a mollusc shell at 98105cm yielded a radiocarbon age of 6,880 ± 85 yr cal BP. These recovered Holocene sediments are predominantly bioclastic carbonates in which foraminiferal tests are abundant. The species of Foraminifera preserved as fossils in this core are extant in modern gulf waters and their
continued next page..
Australian Earth Sciences Convention 2008
57
58 ABSTRACTS
atphafoellcally by syrname of presenting awthor different responses of the crust underlying the Darhng Basin to the Siluro-Devonian extension, Tabberabberan and Kanimblan shortening events resulted in a heterogeneous distribution of strain, whereby granitic-strengthened crust remained relatively stable, responding with only moderate shortening. In the zones between the granitestrengthen-crust, massive inversion occurred, and these zones now correspond to the 'intervening basement highs' where most of the exploration drilling has occurred. These structural highs were uplifted by up to 3km during the Kanimblan and served as focal points for fluid flow during the shortening event. Consequendy, all wells drilled in these areas have significandy reduced porosity and permeability. Only three wells have been drilled outside these focused deformation zones and all recorded intervals of porosity and permeability suitable for subsurface storage of CO2. Further work on these wells is underway to analyse the intervals of interest.
Geodynamics and Basin Evolution
Jane Blevin^ Tom Loutit\ Lynn Pryer\ Karen Romine^ ^ FrOG Tech Pty Ltd. Level 1, 2 King Street, Deakin ACT2600, Australia, tloutit@frogtech.com.au. Horizontal modon of plates results in basin formadon, deformation and destruction. Understanding the structural response to changes in relative plate modons and its influence on basin evoludon is not a simple task. Even in basins that have been studied intensively for many years the relationship between plate modon kinematics, tectonic events and structural response is not certain. In fact some of the most intensively studied basins provide some of the biggest surprises because the percepdon is that everything is known about the basins and the processes that formed them. During the past ten years, our teams have studied many sedimentary basins around the world, using predominandy non-seismic datasets, and have made a number of geodynamics-related observations on basin evolution. One of the key outcomes of this body of work has been the correladon of the timing of tectonic events and the structural response to each event across large areas of the globe. The approach has been to study basins from the "bottom-up" by focusing inidally on the character of the basement. A few of the observadons include: the rate and location of subsidence for each basin phase is controlled by the rheology and mechanical behaviour of the basement; the strength or stiffness is controlled by the composition of the basement; the structural fabric of the basement is a function of the age and early history of each basement terrane; terrane boundaries and the structural fabric control the location of continental rupturing; basement character (fabric and composition) can be used to Australian Earth Sciences Convention 2008
predict which structures will move under an applied stress if the kinematics of relative plate motions are known; and the reactivation of the structural fabric of the basement terranes (cratons or mobile belts) can be used to map/predict the evolution of basin shape and many aspects of petroleum systems.
Petrology of the Savage River Mine sequences. Mr Ralph Bottrill^ Mr Jafar Taheri^ ^Mineral Resources Tasmania The host rocks to the Savage River magnetite deposits are a metamorphosed volcano-sedimentary sequence mosdy comprising intercalated volcaniclastic metamafites and magnesian carbonates, probably of Late Proterozoic age. The main rock types are albitechlorite-amphibole schists and granofels, but also include iron ores, albitites, quartzites, muscovite +!chlorite schists, dolomite and magnesite rich rocks and magnesian skarns. All these rocks were metamorphosed and metasomatically altered but remnant original sedimentary and igneous textures can still be observed in some rocks. Many of the mafic rocks have clastic textures suggesting original basaltic volcaniclastics or lithic arenites, but metadolerites are probably also common. Dolomite and magnesite rich rocks are pardy to totally altered into magnesian and calc-silicate skarns (including amphibolites, serpentinites, talc schists and rarely pyroxene granulites). The main ore mineralogy consists of magnetite (the main ore) and pyrite with minor hematite and chalcopyrite, plus some sporadic apatite-rich zones. These ore minerals are mosdy disseminated to locally massive. Texturally, the ore minerals appear to be largely of replacive origin in various rocktypes, but mosdy occur within breccia and mylonite zones dominated by early carbonates and Mg silicates. The main magnetite mineralisation event was high temperature metasomatism involving magnetite-pyrite replacement of early diagenetic magnesite and dolomite to form pyroxene +!- olivine -h/- serpentine amphibole +!- biotite skarn. Part of the mineralisation (mostly lower grade material) was hosted in intercalated mafic volcaniclastic rocks with intrusive dolerite bodies. The ores have subsequentiy undergone multiple deformational and metamorphic events, including a high pressure - low temperature blueschist facies event followed by retrogression to lower greenschist facies, including mylonites, breccias and veins. Metasomatic events in the mine area include major albitisation, tourmahsation, potassic (biotite) and magnesian alteration. The mineralisation is probably of the Ironoxide-copper-gold class of mineralisation, particularly the Kiruna and Iron-skarn subtypes.
ABSTRACTS alphabetically by surname of presenting author
E.F. Pigot SJ.: The priest who knew about Earthquakes. David Branagan^ ^School of Geosciences University of Sydney. (dbranma @ mail iisycL edii. an) E.F. Pigot S.J. set up the Observatory at Riverview College in 1907. In the following years it became renowned for the quality of the records it obtained. Although Pigot's initial interests lay in astronomy he was unable to afford such equipment. Beginning with meteorological recording he moved to seismic work when Wiechert Seismometers were brought into operation in 1909. Pigot quickly made, and maintained, contact with international figures such as the Russian expert, Count Galitzin, and the Japanese expert Omori. Omorii was visiting the Riverview observatory on 1 September 1923 and together they saw the Great Kanto Earthquake being recorded by the Observatories' seismographs. Pigot carried out the first controlled Foucault Pendulum experiment in the Southern Hemisphere in 1916, with a pendulum suspended within the dome of the Queen Victoria Building, Sydney. Together with J. Pollock he devised and used a photographic system to record the movement of the pendulum. About the same time he carried out measurements of the deflection caused during the construction and filling of the Burrinjuck Dam, using equipment he designed and built locally. Similar plans to work with E.J. Bradfield to measure the deflection caused by the Sydney Harbour Bridge were frustrated by Pigot's death in 1929. Pigot's astronomical work, frustrated through poor visibility during eclipses in 1910 and 1911, came into fruition in the 1920s when he worked with the Sydney University party at Goondiwindi in 1922 and facilitated the visit of a party from the US Lick observatory to observe the eclipse from Western Austraha. The same year he obtained a seven inch telescope, through donation. Pigot's legacy was a record of careful geophysical and astronomical measurements, which gained an international reputation for Pigot and Riverview Observatory. This continued through other Jesuits scientists until the 1990s.
Formation of the eclogite hosting 2.0 Ga Usagaran Orogenic belt, Tanzania.
Rachael A. Brick\ Alan S. Collins^ Martin Hand^ ^ Continental Evolution Research Group, University of Adelaide, 5005, Australia (rachael brick@adelaide. edu. au) Eclogites and other high-pressure lowtemperature rocks have been used to interpret changing tectonic regimes of the earth because the pressure conditions of their formation are equivalent
to those at mantle depths while the temperatures recorded by the mineral assemblages are cooler than those found within the mantle. By studying these rocks we hope to reach a greater understanding of the processes which have built mountains, formed and broken up supercontinents, and generally shaped the earth as we know it today. One of the oldest examples of eclogite in the world is found in the 2.0 Ga Usagaran Orogenic belt in Tanzania. Eclogite lenses in this location are found amongst the felsic gneisses, amphibolites and boudins of ultra basic rocks. The pressuretemperature conditions recorded by these eclogites is -18 kbar & -750 ^C (Moller et al., 1995, Geology, v.23,p.l067). The evolution of these rocks has been investigated using diverse tools to establish whether they were formed in a deep-subduction zone. These methods include sediment provenance, P-T-t modelling of the rocks hosting the eclogites and studies of garnet zonation to establish the rate at which these events occurred.
Rock Tourism & the Black-Footed Rock Wallaby Alan Briggs^ ^The National Trust of Australia (WA) The Black-footed Rock Wallaby (Petrogale lateralis) is a threatened species in Western Australia and is considered vulnerable at both a national and international level. Living on rocky escarpments, gorges, granite outcrops, sandstone cliffs and scree slopes, this once widespread species now occurs in small, fragmented populations on isolated range systems. Populations of Black-footed Rock Wallabies exist in both the Sales Rock and Gundaring Rock Nature Reserves near Quairading, and are representative of a significant proportion of the remaining total population in Western Australia. The National Trust's Natural Heritage Programme protects native vegetation through sustainable management of its own holdings of bush and farmland, conservation covenanting, the BushBank revolving fund, appeals, donations and advocacy. With strategic planning and partnerships, conservation tools may be employed to facilitate a link between these two granite rock outcrops that are protected as nature reserves. In doing so, a corridor for this threatened species will be created, significantly extending the habitats of the existing rock wallaby populations and greatly improving their chances of long-term survival. The linking of the two reserves will also benefit other species and create a much larger, more sustainable area of bushland. There is scope for corporate, landowner and community participation. This paper will expand on this opportunity and consider more broadly other partnerships and links between rock tourism, wildhfe tourism and wildlife conservation.
Australian Earth Sciences Convention 2008
59
60 ABSTRACTS alphabetically by surname of presenting author
Sedimentary and Petrologic Evidence of a Tookoonooka Impact Event Ejecta Layer, Australia Katherine Bron^ Victor A. Gostin^ ^Australian School of Petroleum, University of Adelaide, Adelaide, SA 5005, Australia (tbron @ asp. adelaide. edu. au) ^Department of Geology and Geophysics, University of Adelaide, Adelaide, SA 5005, Australia (victor, gostin @ adelaide. edu. au) A search for an impact ejecta layer for the confirmed subsurface Tookoonooka impact structure (27°07'S, 142°50'E) was undertaken in the lower Cretaceous (Aptian-Barremian) strata of the Eromanga basin of southwestern Queensland. An unusual 5-cm thick layer, observed in core, is believed to represent the impact horizon. This crudely graded, very poorly sorted layer is composed of pebble to fine sand and silt-size, highly angular to rounded clasts. The layer overlies an erosional surface. Clasts are of various lithologies including metamorphic and vein quartz, volcanic and sedimentary rock fragments, feldspars variously altered to carbonate, and iron oxides. Petrologic evidence also includes shocked grains, including probable planar deformation features (PDFs) in quartz. This unit has experienced significant diagenetic alteration, particularly the feldspar component. An investigation of diagnostic shock metamorphic and geochemical signatures is underway. Confirmation of this layer as the impact horizon holds implications for the constraint of impact timing and understanding the paleoenvironment at the time of impact.
The Role of Hydrogeology in Mining Doug M Brown ^
' MWH, Level 7, 178 St.Georges Terrace, Perth WA 6000, Tel: +61 89 211 1400 (dou g. m. brown @ mwhglobal. com) The need for a detailed hydrogeological understanding has become a critical requirement of the approvals, development and closure planning process for new or expanding mining operations. Unlike traditional minerals exploration work the groundwater aspects of a mining project must consider the impact footprint and influences "beyond the mine gate" and within the surrounding regional hydrogeological system. Similarly any assessment must also consider the benefits and challenges of ongoing recharge replenishment of the groundwater resource during operation and closure and also the cumulative impacts of an operation within a catchment with established stakeholders. Australian Earth Sciences Convention 2008
Hydrogeological challenges range from developing sustainable water supplies in areas of highly variable seasonal rainfall, dewatering in advance of mining to establish safe working conditions whilst minimising the off-site impacts of drawdown and discharge, balancing the competing demands of dewatering and sustainable water supply over the life of mine, monitoring and managing the potential impacts on groundwater dependent ecosystems and ultimately closing final voids to minimise long term impacts on the natural groundwater system. Innovative techniques such as the Managed Aquifer Recharge (MAR) of excess mine dewatering discharge are increasingly being evaluated as practical solutions for the preservation of groundwater and minimisation of impacts, where appropriate conditions exist. A case study examining the investigation and application of Aquifer Reinjection by Rio Tinto Iron Ore in the Pilbara is described. This work was recognised as innovative water practice through receipt of the 2007 Management of Water Resources (Commercial) award from the Western Australian Government. Mining hydrogeology is by necessity leading the way in the investigation of regional groundwater environments and in application of applied water management solutions. The learnings from this timely work have the potential for widespread application beyond mining in the development of robust water resource management techniques and options.
The composition and crystallography of gold: implications for ore genesis C.R.M. Butt^ and R.M Hough^ ^CSIRO Exploration and Mining & CRCfor Landscape Environments & Mineral Exploration PO Box 1130, Bentley, Western Australia 6102 (Charles. Butt @ csiro. au)
The compositions and crystallography of nugget and particulate gold from sites in Australia, Papua New Guinea, SE Asia and Brazil have been determined by optical and electron-optical procedures. Preliminary results show that there are distinct differences in the characteristics of gold in different geological environments. The majority of specimens have been collected at or near the surface, but all larger (>4 mm) and many smaller ones appear to be hypogene. Many of even the largest masses (up to 8 kg) have internal evidence of weathering. This includes silver depletion on crystal boundaries, and voids, open to the exterior, that are filled with clay, iron oxide or quartz and commonly hosting small particles of pure, supergene gold. Gold specimens from many deposits in Western Australia, Victoria and New South Wales have silver contents of 5-15%, and an internal equigranular polycrystalline structure that exhibit fabrics which imolv Dost-depositional
ABSTRACTS alpliabetfcaHy by surname of presenting author
deformation followed by annealing at temperatures above 250''C. Fine particulate gold in soil from Amazonia includes polycrystalline grains with internal silver depletion, that probably have a similar genetic history. Some small nuggets from SE Asia, also with annealing fabrics but having a high fineness (<1% silver), are possibly the product of hydrothermal re-mobilization and precipitation. In comparison, some specimens from Papua New Guinea have silver contents 10->30% silver, with variable internal structures including zoning and 'fern-like' crystal habits; these are probably derived from epithermal deposits and have not suffered either deformation or recrystallization since initial deposition. Previous workers have related the fineness of gold to factors such as depth below surface, which in turn relate to temperature and pressure of deposition, and to the effects of weathering. Combining compositional information with crystallographic characteristics offers to provide evidence for the genesis of gold-bearing deposits, including their late thermal and tectonic history.
The Sierras Pampeanas - Puna basin connection: Ordovician crustal thinning and back-arc basin formation at the SW Gondwana margin Steffen H. Buttner^ ^Department of Geology, Rhodes University, Grahamstown 6140, South Africa Lithospheric thinning of extensional continental back-arc regions leads to high heat flow and intense ductile and melt-supported deformation in lithospheric levels susceptible to plastic flow and anatexis. Strain gradients, possibly resulting in the detachment of high- from low-strain regions, may correlate with decreasing depth and temperature and increasing shear strength in the upper more competent crust. The thickness of syn-tectonic sediments deposited in the topographic depression of the back-arc basin may vary depending upon the amount of vertical ductile thinning, thermal uplift and sediment supply. The Sierras Pampeanas and the adjacent Puna basin in NW Argentina record the evolution of the Ordovician SW Gondwana back-arc in complete sections through back-arc basin sediments and the pre-Ordovician basement down to levels close to the crust-mantle boundary. Massive Ordovician mantle heat transfer converted meta-sedimentary rocks into migmatites and granites of the Sierras Pampeanas. Intense syn-anatectic and retrograde ductile extension of the lower crustal migmatites was accompanied by less efficient extension in the upper crust, leading to the detachment of anatectic from non-anatectic crust. Upper crustal extension balanced by newly deposited sediments kept the paleo-pressure constant along the detachment
whereas the crust below the detachment was thinned out by nearly 60% within ca. 35 Ma. At the same time, up to 7000 m marine sediments were deposited in the extensional back-arc Puna basin which overlies the basement of the Sierras Pampeanas. The degree of mechanical coupling between migmatitic lower and more competent upper crust appears to be is the main factor controlling upper crustal extension, basin formation, and sediment thickness within the back-arc basin. The interaction of and the interrelationship between upper and lower crust observed in the northern Sierras Pampeanas and the Puna basin can be considered as a typical example of crustal thinning in the early stages of continental back-arc basin formation.
"Integra Mining's Exploration Strategy and Discoveries-Does one size fit all? Chris Cairns^ ^Integra Mining Ltd, Nedlands Perth WA 6009 (chris @ integramining. com.au) Integra Mining Limited is a Western Australian based gold exploration and emerging mining company. Integra has been an aggressive grass-roots explorer and these efforts have more recently been translated into exploration success with a discovery at the blind Salt Creek gold deposit and the identification of several other advanced discovery targets. The Salt Creek discovery and the other advanced targets are in an area previously not known to host gold mineralisation yet are located only 70 kilometres to the east of Kalgoorlie. In an environment in which emerging markets are expected to drive increasing demand for minerals for an extended period, there has also been an extended period of decline in the rate of discovery of new mineral deposits. This decline in the success rate of minerals exploration indicates that mineral discoveries, and in particular the discovery of 'giant' ore deposits, is becoming more difficult and has important implications for the risk / reward relationship in funding and executing minerals exploration. The history of minerals exploration provides examples of periods of outstanding achievement - as an example, Western Mining Corporation had a 'golden' era in which the Kambalda and Leinster nickel provinces were recognised and a large number of deposits discovered, the St Ives camp of gold deposits discovered and the ultimate discovery at Olympic Dam was made. Other mining / exploration organisations have also demonstrated exceptional achievements over certain periods and study of these successes provides clues as to what will be required to drive the future exploration successes the mining industry will require. It would appear that recurrent themes continued next page... Australian Earth Sciences Convention 2008
61
62 ABSTRACTS alphabetically by suroam© of presenting author
contributing to past exploration success are companies that are on the leading edge of applying technological innovation to exploration, pursuing new frontiers and fostering an organisational culture of discovery. These elements will continue to be the drivers of future minerals exploration success.
Distribution & Ecology of Benthic Foraminifera in the Coorong Lagoon & Adjacent Waters, South Australia; to Aid Palaeo- Reconstructions
Ian H. Campbell\ Charlotte M. Allen^
^ The University of Adelaide, (rachaeLskinner@adelaide.edu.au) ^ University of South Australia, (John, cann @ unisa. edu. au)
Supercontinents, supermountains and the rise of atmospheric oxygen.
^ Research School of Earth Sciences, The Australian National University, Canberra, 0200 (Ian. Campbell @ anu. edu. au) Atmospheric O2 is produced by photosynthesis, which converts CO2 + H2O into organic carbon + O2. If the C produced by this reaction is buried so that it cannot back-react with O2, the O2 concentration in the atmosphere will increase. As a consequence, the rate of increase in atmospheric O2 is controlled by a combination of the production rate of organic C and the efficiency with which it is buried. We suggest that continent-continent colhsions, associated with the formation of supercontinents, produced supermountains that eroded rapidly, releasing a large flux of nutrients (P and Fe) into the oceans. This led to an explosion of algae and cyanobacteria in the upper oceans, and to the release of photosynthetic O2. Furthermore, orogenic episodes are also periods of high sedimentation, which make it more likely that most the organic C produced will be buried during these intervals of high tectonic activity. Increases in atmospheric O2 should therefore correlate with periods of supercontinent formation. We have tested our hypothesis by comparing the age of known increases in atmospheric O2 with the timing of supercontinent formation, which has been constrained by measuring 5758 U-Th-Pb ages for zircons collected from 40 of the world's largest rivers. Five age peaks in zircon production can be recognized that correspond to supercontent forming events: 2.4-2.75 Ga (Superia), 1.6-1.95 Ga (Nuna), 1.25-0.95 Ga (Rodina), 650-400 Ma (Gondwana) and 350-225 Ma (Pangea). Four of the five supercontinent-forming events correlate with recognized step increases in atmospheric O2. The fifth, Rodina, does not but this may be because the missing increase did not trigger a recognizable event in the geological record, such as the disappearance of banded iron formations at 1.8 Ga.
Australian Earth Sciences Convention 2008
John Cann^, Rachael Skinner ^ Jennie Fining Deborah Haynes^ Australia Australia
In 2007 (a drought year), surficial sediments were sampled seasonally for benthic foraminifera from the back-barrier Coorong Lagoon and in the vicinity of the River Murray Mouth, South Australia. The purpose of the study was to compile data relating to the distribution and ecological tolerances of species of foraminifera within these waters, and thus to contribute to the palaeoecological reconstruction of past flow and salinity regimes of the River Murray, and its mouth behaviour. Water quality data - conductivity, total dissolved solids (TDS), pH, dissolved oxygen, temperature, nutrients, chlorophyll a and b and turbidity - were compared with species distribution. No seasonal differences in the distribution of foraminifera species were apparent. The distribution of foraminifera was found to be patchy and dominated by estuarine species Ammonia beccarii and Elphidium excavatum cf excavatum. Closer to the Murray Mouth the diversity of foraminifera and percentage of holomarine species increases. Water quality parameters were not constant across the length of the Coorong Lagoon. The long and narrow structure (>100 km by <4km), combined with drought conditions, reduced marine inflows through the restricted mouth and no freshwater inflows at the southern end, have together resulted in a summer time water salinity gradient ranging from near sea water at the northern end to four times this value at the southern end. Turbidity and chlorophyll a and b increase gradually southwards. Conductivity, TDS, total phosphorous and nitrogen are steady from the mouth to Parnka (midpoint), then increase sharply southward to Salt Creek at the southern end of the lagoon. The trend in these water quality parameters corresponds to increased species diversity towards the mouth. These results will aid interpretation of six cores taken from the Goolwa Channel and Lake Alexandrina and will be applicable to other investigations of sedimentation and palaeoenvironments within the Coorong Lagoon and adjacent waters.
ABSTRACTS aiphafoetically by surname of presenting author
Deep subduction and its expression in plate motions CapitanioF.A/. Morra G.^ Goes S.^ ^ School of Mathematical Sciences, Monash University, Clayton, 3800 VIC ^ Institute of Geophysics, ETH Zurich, Switzerland Dept. Earth Sci. and Eng., Imperial College London, United Kingdom The dynamics of plate tectonics are strongly related to those of subduction. We gain new insights in the thus far elusive dominant forces in subduction, by comparing relations between subduction motions and dips as predicted ty a fully dynamic model for free subduction (i.e., driven solely by downgoing plate buoyancy while resisted passively by the mantle and upper plate), with data for the major subduction zones on Earth. We find that present-day subduction and sinking velocities are as for slabs driven by their own upper-mantle buoyancy, with Stokes velocities that require effective average upper mantle viscosity variations of less than 30% and effective slab widths of 2000-3000 km. Steep dips and high plate advance velocities require a ridge push combined with low-drag asthenosphere (as for viscosity 2 to 3 orders of magnitude lower than the upper mantle average) and effective slab widths at the higher end of those required to fit sinking velocity. Back through the Cenozoic, old plates in the Pacific subducted at rates expected for uppermantle slab pull, while young plates subduction velocities raised up to two or three times those expected from their upper mantle buoyancy. The low trench motions and high subduction rates are compatible with those of a lower mantle -penetrating slab. Weak young lithosphere may be more prone to penetrate the lower mantle, as its lower density and strength limit trench retreat and facilitate slab thickening in the transition zone, which increases Stokes' sinking velocity.
Layered units at the Martian dichotomy and their geological significance.
Graziella Caprarelli^ Monica Pondrelli^ ^ Dept. of Environmental Sciences, University of Technology, Sydney. PO Box 123, Broadway, NSW 2007, Australia (Graziella.Caprarelli@uts.edu.au) International Research School of Planetary Sciences, Universitd d'Annunzio, Viale Pindaro 42, 65127Pescara, Italy (monica@irsps.unich.it) Martian layered deposits have mostly been studied at the poles, where white and grey units cyclically overly. These probably host much of the CO2 and H2O present on the surface of Mars, and play a major role in the study of Martian climate and hydrology. Limited extent layered deposits have
been found also in non-polar regions. Explanations for non-polar layered rocks are non-unique, ranging from sedimentation in aqueous environments to deposition of volcanic ashes. The crustal dichotomy on Mars marks the boundary between the northern hemisphere lowlands and the southern hemisphere highlands. In the eastern hemisphere the boundary is not sharp: hummocky and knobby terrains derived from scarp degradation and subsequent ice weathering are found on its northern side. Caprarelli and Pondrelli (2007, Austral. Space Sci. Conf.) showed evidence of a tectonic control component in the boundary degradation in this region. We used Mars Express High Resolution Stereo Camera (HRSC) imagery and altimetry, complemented by Mars Global Surveyor MOLA and MOC data, to investigate the boundary in the subequatorial northern Terra Cimmeria portion of the eastern hemisphere dichotomy. Here the high quality and resolution of HRSC data allowed identification of peculiar horizontal layering, parallel to the main scarp and to major morphological features on its northern side. The layers are similar to non-polar layered rocks. The localised nature of the observed layers cannot be reconciled to large scale tectonic, erosional or sedimentary processes. Deposition of volcanic ashes or lavas of variable compositions is plausible. To test this hypothesis we carried out investigations of the ancient crust south of the dichotomy to identify possible eruptive vents in the vicinity of the layered units. Future studies will aim to characterise the composition of the rocks to corroborate our conclusions. Here we report on the progress of our investigations.
Lava flows in Pickering Crater, Mars: details from Mars Global Surveyor and Mars Odyssey datasets constrain complex lava flooding history. Graziella Caprarelli ^ Dept. of Environmental Sciences, University of Technology, Sydney. PO Box 123, Broadway, NSW 2007, Australia (Graziella.Caprarelli@uts.edu.au) Pickering Crater is an approximately 130 km diameter crater on the surface of Mars. Its central peak is located at geographic coordinates 132°41'34.34"W - 33°26'57.57"S. The crater is located about 1500 km SW of Arsia Mons, the oldest of the Tharsis Plateau volcanoes. The crater rim underwent substantial erosion by meteoritic impact and mass wasting. The NW portion of the rim is breached. The crater has been infilled by products of erosion and by lavas related to the activity of Arsia Mons. I have used Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) and Mars
continued next page..
Australian Earth Sciences Convention 2008
63
64 ABSTRACTS alphabetlcatty by surname of presenting author
Orbiter Camera (MOC) wide and narrow angle (WA, NA) datasets, Mars Odyssey Thermal Emission Imaging System (THEMIS) visual images, and geographic information systems (GIS) techniques, to observe and interpret geological details in and around Pickering Crater. The crater is covered by about 1.6 km thick rocks and sediments. The most surficial layers are lava flows and aeolian deposits. Tectonic activity is indicated by the presence of three 20 to 30 km long en-echelon grabens, partially infilled by lava, on the present-day floor of the crater, and by fault surfaces in the rim. Lava flow fronts are clearly identifiable in all datasets. The surface features of the youngest lava flows are identifiable by MOC-NA images, and are useful to correlate the flows. Lava flow directions are deduced from THEMIS and MOC-NA images. The presence of dikes is inferred. The combined evidence indicates that lava flows have repeatedly flooded the crater. The youngest lava flows have entered the crater via its NW rim breach. Older lavas record a NNE to SSW flow direction. The relationship between volcanism, grabens and dikes in the Pickering Crater region is complex, and further studies are being conducted to unravel the sequence of volcano-tectonic events in the area.
Comparing Isotopic & Trace Element Geochemistry of the St Peter Suite with Later Gabbroic Intrusions N. C. Chalmers^ ^ B. F. Schaefer\ ^ School of Geosciences, Monash University, Clayton 3800 (NeilChalmers@sci.monash.edu.au; Bruce. Schaefer@ sci. monash. edu. au) ^ Geological Survey, Primary Industries and Resources, South Australia Trace element and isotopic geochemistry provide new insights into the internal complexities and tectonic setting of the calc-alkaline St Peter Suite, western Gawler Craton. The first phase of the suite intruded as a granitic composition followed by a comagmatic phase that included amphibohtes. The later phases of the St Peter Suite are dominated by mafic units that intruded as lamprophyric and gabbroic plutons as well as doleritic dykes. These later mafic phases have identical normalised REE geochemistry, its trend is similar to the trend derived from the early predominantly felsic units, providing evidence for a shared fractionated magma source. One of the units that intrudes the St Peter Suite is a tholeiitic, homogeneous, very juvenile gabbro from St Peter Island. It is high in Ti02 and Fe203 with an enriched REE trend when compared to the St Peter Suite mafic lithologies. Sm-Nd and Lu-Hf isotopic series of the St Peter Suite as well as later units that intrude the suite highlight the subde chemical variations within the Hthologies. The St Peter Suite has sNd values that
Australian Earth Sciences Convention 2008
range from -1.21 to +2.23 and eHf range from +5.66 to +12.37 indicating a relatively juvenile magma. This is in contrast to the tholeiitic homogenous St Peter Island gabbro that intrudes the St Peter Suite which has sNd range from +2.65 to +6.27 and its sHf +9.95 to +13.94 indicating a very juvenile magma source. Geochemical modelling of the trace element data have confirmed that the range of compositions preserved in the St Peter Suite could in fact be formed from a single source through fractionation with some crustal assimilant component. Eurther isotopic modelling suggests that the Hutchison Group metasediments are a reasonable match as the crustal assimilant source to derive the St Peter Suite isotopic compositions.
Restoration of marine ecosystems following the Permian-Triassic mass extinction in Gondwanan interior sea Chen Z.0.\ Haig D.W\ Mory A? ^School of Earth & Geographical Sciences, The University of Western Australia, WA 6009, Australia zqchen @ cyllene. uwa. edu.au ^Geological Survey of Western Australia, East Perth, WA 6004, Australia
The Permian-Triassic (P-Tr) mass extinction redirected dramatically the course of biotic evolution during the Mesozoic and Cenozoic. This event and its consequence have been globally studied. However, few data about this eologic crisis and subsequent recovery are known from Gondwana. Here, we report the restoration of marine ecosystems following the PTr extinction in the Perth Basin, which was part of the interior sea of the Gondwana during the P-Tr transition. The P-Tr boundary and Early Triassic successions are seen in borehole cores as well as outcrop sections in the northern Perth Basin (NPB). A complete P-Tr boundary sequence is revealed in the Well Hovea-3 of the basin. The early Induan succession seen in the Well Hovea-3 indicates a harsh (probably poorly oxygenated) environment. The Lower Triassic (mainly Dinerian-Smithian) is also exposed in the north Geraldton areas, where the stromatolites, resting on either pebbles or sandstone of the Silurian age, characterize the base of the section. Both pustular and smooth stromatolites and their growth patterns, including laminated mats and columns, as well as the associated microbial assemblages are well analogous to modern stromatolites in the Shark Bay. Following the stromatolites sequence, the reddish muddy limestone contains conspicuous wrinkle structures, shell beds and trace fossils. Abundant trace fossils (eight ichnogenera) are present in the above reddish mudstone and siltstone sandstone. Briefly, the ecosystem in Gondwana has been destroyed by the PTr extinction and became unfavorable to most biota expect few disaster taxa within >one modillion years after the event. The ecosystems were slighdy
ABSTRACTS alphabetically by surname of presenting author
ameliorated during the late Induan when stromatolites grew widely in the NPB. The amelioration is indicated by increase in diversity and complexity of trace-fossil assemblages recorded in the Kockatea Shale in the basin.
Episodic anoxic events recorded in the Permian-Triassic transition of the Meishan section, South China: Sedimentary characterization and faunal response Chen Z.0\ Tong Jinnan^ Kaiho K.^ ^ School of Earth & Geographical Sciences, The University of Western Australia, WA 6009, Australia (zqchen @ cyllene. uwa. edu. au) ^ Faculty of Earth Sciences, China University of Geosciences, Wuhan 410073, China; Institute of Geology and Paleontology, Tohoku University, Sendai 980-8578, Japan. The Meishan section, South China is not only the GSSP for the Permian-Triassic (P-Tr) boundary but also the best site to study the P-Tr mass extinction in the world. Most of the most influential studies about the P-Tr crisis are derived from geological data recorded in this section. Nevertheless, the cause of this severest crisis of Phanerozoic life has long been a subject of conjecture, although multiple interpretations and related evidence have been recently released. Of these assumed causes, oceanic anoxia is widely accepted as one of primary causes triggering the P-Tr event. However, any hypotheses interpreting the P-Tr event must be coincident with sedimentary and fossil records throughout the event horizons. Here, we assess ecologically the P-Tr transition by interpreting sedimentary and palaeoecologic data derived from Meishan. To guarantee as much geological information as we can obtain, we collected the complete samples throughout the event from Beds 24e to Bed 30, and then bulk samples from the Lower Triassic in an interval of 5 cm. We examined sedimentary features and fossil fragments in thin sections. In the field we also investigated fossil communities, trace-fossil assemblages, tiring level and bioturbation levels to elucidate biotic responses to various events including anoxia. Our study shows that anoxia do not occur in Bed 24e except for the top 3 cm. Bed 25 may record the anoxic event. There are no signs of anoxia recorded in Beds 26-27 because of diverse brachiopod and foraminifer fauna as well as high bioturbation level. Bed 28 is claystone, no sign of anoxia. Bed 29 is marlstone without sign of anoxia. Bed 30 may be dyoxic, but faunas are fairly rich. The anoxia is probably well indicated at Beds 31-52, where the lithology is dominated by black shale and greenish mudstone and the fauna is dominated by disaster taxa Claraia and Ophiceras. Thus, anoxic events recorded in Meishan may be multi-episodic rather than mono-episodic.
Geochemistry of the West Australian, West Kimberly Province Lamproites. CheslerR^ ^ The University of Melbourne, VIC., Australia; (r. chesler@pgrad. unimelb. edu. au) The West Kimberley Province hosts numerous Miocene age lamproites, which intrude Devonian to Triassic sediments along the southwest margin of the Kimberley Block, Western Australia. Significant geochemical variation exists throughout the region, from olivine-rich, diamondiferous varieties, to leucite-rich, non-diamondiferous bodies. Geochemical analysis of 26 lamproite intrusions was undertaken with the aim of determining the intrinsic geochemical differences between leucite and olivine lamproites, as well as the processes leading to lamproite genesis in this region. Bulk rock major and trace element compositions, plus Sr-Nd-Hf isotopic compositions were measured. These lamproites show extreme enrichment in incompatible elements, and are more enriched in both compatible and incompatible elements than other ultrapotassic rocks. They are characterised by high initial ^^Sr/^^Sr ratios (0.710557 to 0.724391), low ' ' ' m ^ ' m ratios (0.511847 to 0.512230) and show very restricted ^^^Hf/^^^Hf ratios (0.282052 to 0.282236). Olivine lamproites display characteristics which are more representative of those commonly associated with primary magmas. They have high Mg#, high Ni and Cr contents, and low SiOs contents. In contrast, the geochemistry of leucite lamproites appears to have been significantly affected by crustal assimilation, the effects of which can be partially quantified by the use of the contamination index (C.L) of Clement (1982, Unpublished PhD thesis. University of Cape Town). Leucite lamproites exhibit a positive correlation between C.L and ^^Sr/^^Sr and show the highest C.L values. This suggests that these samples have been modified by interaction with the continental crust. It is proposed that the range of compositions within this province could be due to varying amounts of crustal assimilation.
Australian Earth Sciences Convention 2008
65
66 ABSTRACTS
alphafoeticallf by surname of presenting author
Predicting geophysical targets using reactive transport geochemical models Richard Chopping^ James Cleverley^, Paul Henson^ Indrajit GRoy ^ pmd'^CRC, GPO Box 378, Canberra, ACT, 2601 ^ pmd-^CRC, CSIRO, ARRC, 15 Dick Perry Ave, Kensington, WA, 6151 (James.ckverievCSx'siro.au) The development of coupled fluid-flow and chemical reaction (reactive transport, or RT) models within the predictive mineral discovery Cooperative Research Centre (pmd-^CRC) allows for the simulation of key ore-forming processes. These models demonstrate how alteration varies both spatially and temporally. The mineralogy of any crystalline rock controls l«y physical properties such as its density and magnetic susceptibility. Many authors in the literature have explored methods to relate physical properties to mineralogy; these methods can produce physical property models from the RT models. The computed physical property models represent the subsurface properties for a restricted period of geological history, set by the RT model, which generally does not simulate to present day. Geophysical methods respond to the subsurface properties as they are today, so there is a need to simulate processes such as erosion or regolith which have occurred after the cessation of alteration. Postalteration processes are simple to model: they are modelled by removing the top of the model or adding material with properties similar to modemday regolith. Once realistic physical property models are created, they can be forward-modelled to determine their geophysical responses. Different survey types, designs (gravity station spacing, or line spacing and flying heights for airborne surveys), and weatheringregolith scenarios can be evaluated. Comparison of the geophysical response of the initial (unaltered) and final (altered) models allows geophysical targets to be created which are purely due to alteration. These geophysical targets are based on our simulation of the ore-forming processes and thus link the ore processes with the mappable geophysical responses. A comparison between a simple gold-forming reactive transport model and known mineralisation indicates that coupling a geochemical model to geophysical modelling can predict robust and geologically constrained geophysical targets.
Australian Earth Sciences Convention 2008
U-Pb isotopic age constraints on event timing in the Southern Granulite Terrane, India. Chris Clark^ Alan Collins^ Peter Kinny\ Ian Fitzsimons\ & Rich Taylor^ ^The Institute for Geoscience Research (TIGeR), Curtin University of Technology, GPO Box U1987, Perth, WA 6845 (c.clark@curtin.edu.au) ^Continental Evolution Research Group, The University of Adelaide, Adelaide, SA 5005 ^The Grant Institute, University of Edinburgh, UK. The Southern Granulite Terrane (SGT) in India lies to the south of the Archaean Dharwar craton and consists of Palaeoproterozoic orthogneisses, metasedimentary rocks, and charnockites. The SGT can be divided into a number of terranes based on protolith and thermal/deformational events. The Salem Block that lies immediately south of the Dharwar Craton and continue as far south as the Palghat-Cauvery shear system (PCSS). The PCSS is a >100 km wide, crust-cutting, system of anastomosing shear zones that cuts migmatitic mafic gneisses, and contains high-pressure granulites. The Madurai and Trivandrum Blocks lie south of the PCSS and are separated from each other by the Achankovil shear zone, an enigmatic structure with a pronounced magnetic and seismic anomaly. Both the Madurai and Trivandrum Blocks were extensively deformed and metamorphosed to granulite-facies during the Neoproterozoic. The Salem Block charnockites give a magmatic age of -2.54 Ga and are cross cut by undeformed leucogranites with overgrowth ages of -2.48 Ga. No evidence for Ediacaran-Cambrian overgrowths were observed in this area. PCSS rocks have an inherited Archaean/Palaeoproterozoic zircon component. Rims on inherited cores and newly formed metamorphic grains yield an age of -0.53 Ga older than those analysed in monazites at -0.52 Ga. The Madurai Block metasediments also contain an Archaean detrital zircon component. The U-Pb age spectra of detrital zircons in these metasedimentary gneisses indicate that their protoliths were deposited after -1700 Ma. U-Pb zircon and monazite data yield distinct age populations possibly related to thermal pulses within the Ediacaran-Cambrian orogenic event. The rocks in the Achankovil shear zone have anomalously juvenile isotopic compositions and model ages relative to the bounding Madurai and Trivandrum Blocks. Detrital zircons from metasedimentary gneisses along the southern margin of the Achankovil shear zone yielded Neoproterozoic maximum depositional ages. Metamorphic U-Pb zircon and monazite data yield ages between 0.55 and 0.52 Ga.
ABSTRACTS alphabetically by surname of presenting author
The protoliths to many of the metasedimentary gneisses in the Trivandmm Block were sourced from Palaeoproterozoic and NeoArchaean rocks and were deposited some time after c. 1900 Ma. The gneisses were subsequently metamorphosed during the Ediacaran-Cambrian with monazite and zircon growth recording events at 0.56, 0.54 and 0.52 Ga.
Mechanical and thermal reworking of the Vestfold Hills, East Antarctica. Chris Clark^ Alan Collins^ Pete Kinny^ Martin Hand^ ^The Institute for Geo science Research (TIGeR), Curtin University of Technology, GPO Box U1987, Perth, WA 6845 (c.clark@curtin.edu.au) ^Continental Evolution Research Group, The University of Adelaide, Adelaide, SA 5005 The Vestfold Hills (VH) on the Prydz Bay coast of East Antarctica provide an outstanding natural laboratory to study the interplay between thermal and mechanical processes in the reworking of continental crust. The Vestfold Hills are composed of anhydrous felsic orthogneisses and garnet-orthopyroxene rich paragneisses that were twice metamorphosed to granulite grade during the late Archaean. The garnet-orthopyroxene paragneisses have a strongly developed foliation and lineation that developed at granulite facies conditions during the M2/D2 event in the Late Archean. The lineation plunge, defined by quartz-feldspar melt aggregates and aligned orthopyroxene crystals, are consistent throughout much of the Vestfold Hills where they plunge moderately steeply to the NW. However towards southwestern end of Mule Peninsula this orientation becomes rotated to the west by 10-15° and the plunges are 5-10° shallower. This fabric rotation is the only evidence in the bulk of the gneisses for a post M2-D2 structural event. Mechanical reworking of the gneisses is most easily recognised in the selective reactivation of pre-existing structural weaknesses such as the networks of pseudotachylites and brittle faults that dissect the VH gneisses. Conjugate sets of pseudotachylite with extensional kinematics are frequent. Moving towards the southwest the northwest striking west dipping faults and pseudotachylites are preferentially reactivated into discrete mylonite zones that exhibit dominantly dextral surface kinematics, have variable steep to moderate lineations and a top to the east thrust sense of movement. Moving further towards the southwest the orientations of shear zones are rotated -20° westward and the extensional pseudotachylite/faults disappear. The NW-SE oriented shear zones become more prevalent and develop amphibolite facies g-plbi assemblages. Towards the tip of the Mule Peninsula these shear zone become wider and are
spatially associated with emplacement of garnet bearing pegmatites. The reactivation of brittle faults/shear zones was most likely associated with mid-crustal metamorphism and the influx of pegmatite. The generation of pegmatite from previously dry rocks requires fluid, and the spatial association of reworking and pegmatite implies that fluids played an important role in the destabilisation of the VH crust. The thermal effects reworking in the VH is observed primarily as recrystallisation of the mafic dyke sets. NNW trending FES dykes develop gt-cpx aggregates NNE trending FE4 dykes also recrystallise but do not develop obvious gt instead contain opx-cpx-pl aggregates. Gt-cpx aggregates define a shape fabric in the FE3 dykes that become more pronounced to the south. Fracture sets containing garnet occur in both sets of dykes. The intensity of dyke recrystallisation decreases moving further to the north and east.
The Difference Between a Rock and a Hard Place: Using Geology to Add Value to the Nature-based Tourism Experience Associate Professor Ian Clark\ Professor Patrick James \ Professor Jane James^ ^School of Natural & Built Environments, of South Australia, Australia ^Flinders University, Australia
University
Brachina Gorge in the Central Flinders Ranges of South Australia provides a unique section across the geological record. In a distance of less than 20 km the rocks present a record of the evolution of the Earth System during the period from about 700 Mya to 500 Mya. The combination of a semi-arid climate and a deeply eroded, narrow gorge allows an almost continuous outcrop of moderately- to steeply-dipping sedimentary rocks to be viewed. These rocks contain evidence for the early evolution of the atmosphere, climate change,and the evolution of the biosphere from cyano-bacteria (stromatolites) to complex life forms including the Ediacaran fossils and the subsequent Cambrian fauna . It is possible for visitors to stand with one foot on either side of the Cambrian -Precambrian boundary or to see a thin layer of rock produced 600 Mya when a huge meteorite hit the Earth several hundred kilometres to the west. As well as these unique features there are all of the more regularly encountered features of a sequence of sedimentary rocks that have undergone deformation and have been exposed on the Earth's surface for more than 400 million years. All of these features have made this an area of interest which has been visited for many years by researchers, undergraduate classes, K-12 classes and most recently by the general public. The incorporation of the gorge into a National Park and a general increase in experiential and nature-based continued next page... Australian Earth Sciences Convention 2008
67
68
ABSTRACTS afphabeticaliy by surname of presenting author
tourism has meant that the area is visited by many people who are unable to interpret the geology of the area and who, without help, remain unaware of its particular significance. This has resulted in a partnership between the National Parks Service, the Geological Survey and the University of South Australia to provide information suitable for interpretation by visitors. Signs, a brochure, a coloured book, a geological map and information in an Interpretive Centre have been prepared as well as a training program for Park Rangers and tour operators.
Architecture of an Entrenched Valley Fill, Murray River Jonathan D. A. Clarke^ ^CRC LEME/Geoscience Canberra, ACT ion, clarkeitma. go v. au
Australia, 2601,
PO Box 37, Australia,
The Murray River downstream of Wakool Junction occupies an incised valley system for most of its remaining length. The valley is incised progressively deeper into the Cainozoic sediments of the Murray Basin and becomes narrower downstream, forming the Murray River Gorge. Airborne lidar surveys have revealed considerable detail about the floodplain morphology not evident in other data sets. Within the alluvial fill the modern floodplain is further inset below the level of a Pleistocene terrace. The modern floodplain consists of three distinct generations of meander belt sediments composed of scroll bars and oxbow billabongs. These show distinct up and down-stream morphologies reflecting spill-over of sands during river floods. A conventional fme-grained floodplain is absent because of the meander belt sediments extend across the full width of the floodplain. However, older meander deposits are draped by floodplain silty clays with the thicknesses increasing to more than a metre with the older deposits. The oldest floodplain deposits also show distinctively long meander wavelengths and wide channels than the modern channel. Highly sinuous fixed-channel anastomoses form major tributaries and are related to drainage during high water levels. These channels and the oxbow billabongs are clay lined. The terrace consists of similar deposits with thicker mantling of both floodplain sihs and clays and aeolian silts and sands. Despite these mantles, ghosts of channels and billabongs are visible in satellite imagery. Mapping the floodplain morphology and the sediment facies are an important part in predicting hydrogeological properties of the alluvial fill of the Murray River trench, including surface and subsurface recharge, presence of flush zones, and perched water tables. Australian Earth Sciences Convention 2008
The Dalhousie Mound Spring Complex as a guide to Martian Landforms and Processes Jonathan Clarke\ Mary Bourke^ Peter Nelson^ Michael Manga^ and Julia Fonseca"^ ^ Mars Society Australia, PO Box 327, Clifton Hill, VIC, 3068, Australia. ion.clarke(a)Mgpomi^om ^ Planetary Science Institute, Tucson, Arizona AZ 85719, United States ^ Department of Earth and Planetary Science, University of California, Berkeley, California, United States ^ 15 E. Elm St., Tucson, AZ 85705, United States Possible springs and their deposits are important targets for Martian exploration because of the information they contain about Martian landscapes and processes. They also indicators for conditions in the Martian subsurface hydrosphere, are potential habitats for past (and present) Martian organisms, and have resource potential for human missions. Studying of terrestrial springs can provide insights into how past and present Martian springs and their deposits might be recognised and studied. One such spring system is the Dalhousie Mound Spring Complex (DMC) in central Australia, near the border of South Australia and the Northern Territory. The DMC is one of largest groundwater discharge landforms known on Earth and is an excellent field laboratory to develop models of spring related landform evolution on both Earth and Mars. The DMC also allows development of recognition criteria for spring deposits at the satellite, lander, and microscopic scales, and investigate issues associated with their exploration. Studies by the researchers have shown that the landforms of the DMC have a number of similarities with a range of small mound and cone features on Mars. Modelling of the dynamics of spring systems has successfully predicted their morphology. The dynamics of any Martian springs could likewise be predicted. Fourteen specific microfacies have been identified, belonging to seven facies. These were deposited in three environmental associations: cool to warm tufa depositing springs (<40^), warm to hot mixed tufa-travertine depositing springs (40-80^), and hot travertine depositing springs (<80 ). Pool, marsh, and outflow channel environments can be recognised from petrographic textures. Diagenesis has occurred in several stages. From earliest to youngest these are: phreatic diagenesis during initiation and main discharge of the spring, vadose zone diagenesis during the collapse of spring discharge, and a range of pedogenic overprints by clays, sulphates, and iron oxides-hydroxides in remnant cavities.
ABSTRACTS alphabetically by surname of presenting author
Predicting compositions of white micas in lode gold systems: results of numerical modelling.
The Palaeontology and Palaeoecology of the 2.7Ga Tumbiana Formation, Pilbara Craton, Western Australia.
Evgeniy BastrakoV, Yuri Shvarov^, James Cleverley^
Jessica M CoffeV, Malcolm R. Walter^ Simon C. George^ Andrew HilP
^ prnd'^CRC at Geoscience Australia, GPO Box 378, Canberra, ACT, 2601, Australia (Evgeniy.Bastrakov@ga.gov. au) pmd'^CRC and Moscow State University,Moscow, 119992, Russia (yshvarov@geol.msu.ru) ^ pmd'^CRC at CSIRO EM, PO Box 1130, Bentley WA 6102, Australia (James.Cleverley@csiro.au)
^ Department of Earth and Planetary Sciences, Macquarie University, Sydney (jcoffey@els. mq. edu. au, mwalter@els. mq. edu. au, sgeorge@els. mq. edu. au) Centro de Astrobiologia, Madrid, Spain (hilla@inta.es)
Variability in compositions of white micas is well known for alteration zones of the Archaean lode gold deposits and has been suggested as an exploration tool based on PIMA and hyperspectral data. However, quantitative controls on mica compositions are not well understood. Using geochemical modelling, we have examined variations in white micas composition in response to changes in host lithology and fluid composition (fluids equilibrated with basalts or granites). In all the examined models, the driving mechanism of gold precipitation was desulphidation of fluids resulting from wall-rock alteration (infiltration metasomatism). Numerical experiments predict the following. Distribution of paragonite v^ muscovitephengite. Paragonite is developed in the altered basaltic rocks, with only minor paragonite observed in granites due to the infiltration of a "basaltic" fluid. The paragonite zone in basalts is distal relative to the fluid feeder position and lies outside of zones of gold mineralisation which are associated with the muscovite-phengite alteration. Muscovite-phengite solid solutions. For alteration zones proximal to the fluid feeders, muscovites enriched in the phengitic component are developed from the "granitic" group of fluids, whether the initial fluid is oxidized or not. For "basaltic" fluids, there is only subtle correlation between mica compositions and gold grade that is of little use in exploration practice. For "granitic" fluids, there is a correlation between white mica composition and localisation of gold mineralisation associated with sulphidic zones. However, depending on the host rocks, compositional trends in micas might be opposite despite the same composition of the initial fluid. Correlation of gold distribution and sulphidation zones with mica compositions requires site-specific calibration based on the local host rock types.
The Neoarchean (2.5-2.8Ga) was a critical time for life on Earth during the transition to an oxygenated environment. Of the many fossiliferous successions known from several continents, the 2.7Ga Tumbiana Formation stands out for its overall quality of preservation and the extent of its outcrop. The Tumbiana Formation is hosted within the length of the Fortescue Basin in the Pilbara region, NW Australia. The unconformably underlying granitegreenstone basement provides an impermeable hilly foundation onto which the Tumbiana Formation accumulated. In the eastern border of the NW Pilbara sub-basin, the Tumbiana Formation is a 200m sequence containing sheet basalt flows, thick beds of accretionary lapilli, diamictites, volcaniclastics and pillow basalts, and is capped by ~20m of stromatolitic carbonates. The western border of the sub-basin (500km west) contains <2m of stromatolitic carbonates, bounded by subaerial and subaqueous basalt flows and volcaniclastics. The fossilised stromatolites are Fe-rich dolomites commonly laminated and infilled with volcanic tuffs among pale and kerogenous-dark laminae. The Tumbiana Formation stromatolites range in size and morphology from millimetre scale smooth-lamina bulbous structures, to decimetre conical laminae structures and wavy-laminae, low synoptic relief-elongate domes of over 3m in length. The conical stromatolites consist of steeply convex laminae, with a thick and shifting apex, uneven column margins and no branching. Comparable extant forms are built by filamentous, photosynthetic, phototactic microbes. Although the succession has undergone greenschist facies metamorphismthis unit will be an important target within the Tumbiana Formation for confirmation of controversial cyanobacteria reports from previous biomarker studies. The stromatolite sequence will be the focus of biomarker analysis, comprehensive stable isotope studies and rare earth element analysis to fully gauge the environments and ecology at this time.
Australian Earth Sciences Convention 2008
69
70 ABSTRACTS aiphabeticaUy by surname of presenting author
Formation of a Supercontinent, Framework of the Super-Resource: The East African Orogen and the Amalgamation of Arabia Alan S Collins Geology & Geophysics, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005. alan.collins@adelaide.edu.au The Arabian Peninsula hosts the largest known accumulation of petroleum reserves on the planet and significant metallic mineralization hosted in Neoproterozoic rocks. Late Neoproterozoic rocks also form a significant petroleum source in the Peninsula and much interest is focussing on possible Neoproterozoic-Cambrian petroleum plays. Arabia amalgamated during the formation of the Gondwana supercontinent and the region forms the northern extension of the East African Orogen one of the largest orogens preserved on the planet. Despite this, there is considerable uncertainly about the palaeogeography of the basement protoliths and questions such as: when did the terranes amalgamate; how do individual terranes correlate with North Africa, or India; and what was the tectonic environment of formation of the Ediacaran source rocks, excite considerable controversy largely because the key rock-packages are incompletely dated, far-separated, lack focussed tectono-sedimentary analysis and have not been treated within an orogen-scale framework. The East African Orogen is quite unique in the range and extent of crustal levels preserved along the orogenic strike. In the south, one of the mostextensive lower crustal outcrops found anywhere on the planet stretches from Mozambique, through East Africa, southern India and Madagascar (contiguous crust in a reconstructed Gondwana) to pass north and up in the crust to the vast upper-crustal rocks of the Arabian-Nubian Shield of the Horn of Africa, Egypt and Arabia. Individual sutures and tectonic units can be traced along orogenic strike, and at least two individual orogenies can be separated within the orogen. These are the -640-630 Ma East African Orogeny and the -560-520 Ma Malagasy Orogeny. Here I will present an animation of the world from 750 Ma to 520 Ma, based on available goodquality and reasonably dated palaeomagmetic resuhs and a vast amount of geological data collected and published by many workers. The East African Orogen will be placed in this context and in particular I will discuss why I interpret the East African Orogeny to be due to the collision of the microcontinent Azania (central Madagascar, much of Somalia and the Al-Mafid block of Yemen) with the Congo-Tanzania-Bangweulu Block of Africa (with the Saharan metacraton to its north) and the later Malagasy orogeny to be due to the collision of India with this amalgam. I will also propose that Australian Earth Sdences Convention 2008
Arabia did not amalgamate until after 600 Ma ago and that Oman and the Saudi Arabian Shield were separate blocks until -580-560 Ma with a suture passing close to the Yemen-Oman border and heading north through the Rub-al-Khali.
Geological History of the Flying Fox Nickel Deposit, Forrestania Greenstone Belt, Yilgarn Craton, Western Australia: A Preliminary Assessment Collins. J.E.\ Hagemann, S.GJ McCuaig, T.C.\and Frost, K.M? ^ Centre for Exploration Targeting, School of Earth and Geographical Sciences, M006, The University of Western Australia, 35 Stirling Highway, CRAWLEY Western Australia 6009, Australia: (coUij02@student.
uwa. edu. au)
^ Newexco Pty Ltd, 15 Joel Terrace EAST PERTH Western Australia 6004, Australia The Flying Fox deposit is a 2.9 Ga komatiitehosted nickel deposit located in the Forrestania greenstone belt of the Yilgarn Craton in Western Australia with a total ore reserve of 1.39Mt @ 6.5% Ni. The lithostratigraphy at the Flying Fox deposit comprises footwall meta-sedimentary rocks, overlain by a meta-komatiite-basalt succession intercalated with three meta-sedimentary sequences, which is overlain by a hangingwall metasedimentary shale. These rocks are metamorphosed to mid- to upper-amphibolite facies with estimated peak metamorphic temperatures at 655°C±30°C and 4.0±1.0kb. Three intrusive events have been identified at the Flying Fox deposit: (i) pre-peak metamorphic adamellite intrusions; (ii) post-metamorphic intrusions of granitic rocks; and (iii) E-W trending Proterozoic dolerite dike. The ore-bodies at the Flying Fox deposit have undergone five phases of deformation resulting in up to three phases of mechanical sulfide remobilization into and at the contact of the footwall metasedimentary rocks, segmentation of the original ore body and the dislocation of ore into and at the contact of the granitic intrusions. Upper amphibolite metamorphism likely converted nickel sulfides to Mss, thereby increasing the ductility and enabling the nickel sulfide ore to relocate along zones of weakness (eg fauhs/shears and fractures). Hydrothermal fluids accompanied these deformation events, however are not related to the remobilization of the sulfides. Deformation has resulted in five ore-bodies which display four styles of sulfide mineralization: (i) disseminated; (ii) massive; (iii) stringer/vein; and (iv) breccia/matrix. Sulfides are comprised of pyrrhotite, pentlandite, pyrite and minor chalcopyrite and all but the disseminated sulfides are
ABSTRACTS alphabetically by surname of presenting author
remobilized. The deposit is open at depth and recent drilling has delineated another ore-body (T6/T7). The present geometry and distribution of stratigraphy and ore-bodies at the Flying Fox deposit reflects a complex interplay of primary and secondary processes. Recognition and understanding of these processes and their affects on nickel sulfides will further aid in exploration success.
Quaternary Evolution of Scott Reef, Australia's North West Shelf Lindsay B. Collins \ Andrew V Shuckstes^, Michael Page^ ^ Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth 6845, L Collins @ curtin. edu. au ^ WorleyParsons, Level 7, 250 St Georges Terrace, Perth, 6000, andrew.shuckstes@worleyparsons.com ^ WorleyParsons, Level 7, 250 St Georges Terrace, Perth, 6000, michael.page@worleyparsons.com The North West Shelf is a modern tropical ramp which is underlain by Cretaceous-Tertiary limestones. Coral reef systems, discontinuously developed, vary from fringing reefs to isolated reefs which rise from deep-ramp settings. Evolution of the reef systems is being documented using seismic imaging, coring, bathymetric imaging and U-series dating. Scott Reef (at 14oS) is a macrotidal, isolated reef which overlies a carbonate platform and a major gas discovery. It has recently been the site of coral bleaching and studies of such disturbances are ongoing. Seismic profiles reveal a buried Last Interglacial (MIS5, ca. 125,000 year) reef system, in contrast to the widely exposed reef of similar age along the Ningaloo coast, such that reefs which apparently grew to sea level are now 30m below present sea level, indicating significant subsidence in the Late Quaternary. Contemporary reefs grew during the Holocene (last 10,000 years) in the accommodation space provided by subsidence and are up to 35 m thick. These reefs have growth rates similar to those recorded for tropical reefs elsewhere. New, preliminary data have provided a greater understanding of the growth history of Scott Reef and the timing of sea-level events. The interaction of subsidence and glacial-interglacial sea-level change has resulted in multiple events of reef growth, each separated by periods of emergence and karstification, so that the reefs resemble a series of "stacked saucers" atop a 400m high carbonate platform.
Magmatic V-Ti-Fe mineralization Barrambie, Western Austraha
at
Peter L.F. Collins ^ B r y a n Smith 7. Department of Applied Geology, Curtin University of Technology, Perth WA, Australia 2. Reed Resources Ltd, 97 Outram Street, West Perth, WA Australia 3. Bryan Smith Geosciences, 47 Tain Street, Applecross, WA Australia The orthomagmatic V-Ti-Fe deposit at Barrambie, in central Western Australia, is a significant long-term source of vanadium and titanium. The high-grade deposit is part of a nearvertical layered, anorthosite-gabbro intrusive complex (Barrambie Complex) that has been emplaced into the Archaean Barrambie Greenstone Beh. The Barrambie Complex is 500-1700m thick and has a strike length of at least 22 km. It is blanketed by colluvium and residual lateritic capping above a weathered profile that extends for up to 80m below surface and has distinct geochemical profiles. V-Ti-Fe mineralisation occurs as cumulative segregations of vanadiferous magnetite and ilmenite within a 150-200m thick anorthositic zone. Most of the mineralization, in the 'Central Bands', consists of massive bands and lenses (>80% magnetite-ilmenite) that are separated by layers of anorthosite-gabbro with disseminated magnetite and ilmenite. The eastern margin of mineralization is defined by a continuous, 20-30m thick, massive Ti-enriched 'Eastern Band'. The magnetite-rich layers are continuous over at least 11 km strike length (with small fault offsets). Coarse granular magnetite and ilmenite are the dominant primary ore minerals with much of the ilmenite present as lamellae within magnetite grains. Within the weathered profile magnetite is almost completely altered to hematite (martite) and ilmenite is partially altered to leucoxene. Vanadium is mostly in solid solution in magnetite (martite), which contains up to 3.6% V2O5. There is a distinct bimodal distribution of V and Ti composition of the ore, which is similar to several other magmatic V-Timagnetite deposits in layered intrusive complexes elsewhere in the world.
The Phanerozoic: Reconciling modern plate tectonics with ancient orogenic systems and crustal growth W.J. Collins^ A.I.S. Kemp^ ^School of Earth Sciences, James Cook University, Qld, 481L (bilLcollins@jcu.edu.au) (tony. kemp@jcu. edu. au) Phanerozoic Earth history affords us the precious opportunity of understanding the links continued next page.. Australian Earth Sciences Convention 2008
71
72 ABSTRACTS alphabetically by surname of preseming author
between active tectonic processes and crustal growth, because we have the oceanic and continental record to combine into a coherent, whole-Earth geodynamic model. Such integrated models might then be applied to the Precambrian with some confidence. Phanerozoic orogenic systems can be grouped into two broad types: accretionary (circumPacific) and coUisional (Alpine-Himalayan in Mesozoic-Cenozoic; Appalachian-Variscan in Paleozoic). These two systems reflect the effects of simple, long-term (500 Ma) mantle convection involving two global cells separated by the circumPacific subduction zone (Collins 2003, EPSL 205, p.225). Accretionary orogens form in the "Panthalassan" cell, where diverging Pacific Ocean crust prevents entry of continental fragments into that cell, thereby creating a stable, long-lived subduction zone, and equally long-lived, circumPacific orogenic system. In contrast, collisional orogens form in the "Pangean cell, which is traversed by a single subduction system (AlpineIndonesian). This system is intrinsically unstable because continental fragments exist on the subducting plate. The instability causes MOR- and trench-jumps in the Indian Ocean, which have combined to progressively fragment and transfer Gondwana northward into Asia. Arrival of Gondwanan fragments at the subduction zone completes the Wilson cycle, which characterizes most Phanerozoic collisional orogenic systems. Crustal growth is more likely to occur in accretionary systems, as collisional systems are largely continental transfer. However, exceptions occur in both. For example, the Andes seem to record little or no net crustal growth over almost 500 Ma. Rapid crustal growth seems to be confined to accretionary systems where large oceanic backarcs fill with turbidite, then are reworked into continental crust during alternating advance and retreat of the outboard subduction zone. The Paleozoic Tasmanide orogenic system of eastern Australia is an excellent example. The processes described above suggest that crustal growth mainly occurs by backarc opening and closing, not by crustal accretion at the arc front, which is borne out by the isotopic record of zircon growth on the Australian continent.
The AuScope Far North Queensland Survey. WJ. Collins ^ Brian Kennett^ and Bruce Goleby^ ^ James Cook University, Townsville, Qld, 4811, Australia (billcollins@jcu.edu.au). ^ Research School of Earth Sciences, ANU, Canberra ACT, 0200,, Australia. ^ Geoscience Australia, PO Box 378 Canberra ACT 2601, Australia. The Australian Government's National Collaborative Research Infrastructure Strategy (NCRIS) initiative awarded AuScope (h ttp: //www. auscope. or g. au/) $42.8 million to support geoscience. AuScope will establish worldclass infrastructure to characterise the structure and Australian Earth Sciences Convention 2008
evolution of the Australian continent in a global context, from surface to core in space and time; and provide better understanding of the implications for natural resources, hazards and environment. The Earth Imaging and Structure (ANSIR) component of AuScope is focused on providing 3D databases of geologically important regions, which will be achieved through the collection of GeoTransects. AuScope will collaborate with, and use the services of ANSIR to achieve this. In August 2007, the Far North Queensland (FNQ) Tasman Line project became the first AuScope Traverse to be acquired. This survey links with the GA/GSQ Isa-Georgetown-Charters Towers survey and together, provide an exceptional opportunity to image this important region of Australia crust in three-dimensions. FNQ best preserves the Tasman Line, which is the boundary between the Precambrian craton of Australia, and the Phanerozoic Tasmanides to the east. The correlation between the lithosphericscale structures evident in the seismic tomography images with mapped surface structures from observed geology suggests that this region is ideal for investigating the relationship between major upper crustal province boundaries and major features observed in geophysical images. The FNQ AuScope Reflection Traverse will address important questions regarding the nature of continental growth in eastern Australia. The raw field stack indicates a significant change in Moho depth on either side of the Tasman Line, considerable coherent reflectivity within the middle crust and evidence of shallow mid-cmstal structures. However, the seismic imaging does not indicate the presence of a single major structure that corresponds with the Tasman Line. The data now requires processing to enhance the seismic image within the upper crust.
Trace Elements In Sphalerite: Concentration Levels And Mode Of Incorporation. Nigel J. Cook^ William Skinner^, Cristiana L. Ciobanu^ Allan Pring^ Masaaki Shimizu"^ And Leonid Danushevskiy^ ^Natural History Museum, University of Oslo, Norway: nigelc&,nhm. uio. no ^lan Wark Research Institute, University of South Australia, Adelaide, S.A., Australia, ^South Australian Museum, Adelaide, S.A., Australia ^University ofToyama, Japan ^CODES, University of Tasmania, Hobart, Tasmania, Australia Sphalerite from >20 ore deposits has been analysed by LA-ICP-MS for Ag, As, Bi, Cd, Co, Cu, Fe, Ga, Ge, In, Mn, Mo, Ni, Pb, Sb, Se, Sn and Tl. The suite included samples with wt.% levels of Mn, Cd and In. The aim was to better constrain solid solution ranges in the context of crystal chemistry and phase relationships, distinguish between solid solution and microscale inclusions, and to identify
ABSTRACTS alphabetically by surname of presenting author
geological controls on sphalerite geochemistry. Relationships between chemical heterogeneity at the micro-Znanoscale, and bulk internal mineral structures in sphalerite have implications for mineral processing and environmental remediation. We conclude: - LA-ICP-MS gives accurate trace element data for sphalerite. Lead, Ag and Bi are most commonly encountered as micro-inclusions, rarely as solid solution. - Sphalerite is characterized by a specific range of Cd (-0.2-1.0 wt.%) in each deposit. Higher concentrations are rare; spot analyses show up to 13.2 wt.% (Cd^^^Zn^^ substitution). - Sphalerite from Toyoha, Japan contains complex zoning. In-sphalerite (up to 6.7 wt.% In) coexists with Sn-sphalerite (up to 2.3 wt.%). Indium concentration correlates with Cu, corroborating coupled substitution. Sn correlates with Ag, suggesting substitution. - We observe inverse correlation between Mn and Fe in several samples. Mn-enrichment (up to ~4 wt.%) does not enhance incorporation of other elements. - Most element concentrations vary significantly between, and often within, single samples. Local enrichment in In, Ge, Ga and Co from different localities. Ge-bearing sphalerite shows little evidence of coupled substitution: Ge may be present as Ge^^ rather than Ge^^. - Trace element concentrations and fractionation of a given element into sphalerite are influenced by type of deposit, crystallization temperature, metal source, cooling history and proportion of sphalerite in the ore. - Our results also allow recognition of new, previously unrecognised economic targets (e.g., for In, Ga or Ge).
The Art and Science of Data Analysis Building Talent for Future Resource Management Jacqui Coombes^
And what of the "press button" approach to learning? What is the impact of this on a person's creativity - specifically the impact on a person's ability to visualise an alternative not yet digitally captured? Our challenge is this: Within the technological context, the current educational paradigm and the fast-track-me mentality of generation Y, how do we develop geologists with the logic and imagination to create realistic models of our resources that form the basis of our industry? The key lies in the development of both scientist and artist in our geologists. This requires firstly a fundamental grasp of logic and the ability to present and test hypotheses. We develop analytical logic through systematic training in processes, evaluation of alternatives and through persistently asking "Yes, but why?" Secondly, we need geologists with the courage to use their imagination. This means they need to be comfortable to try, and to realise it is okay to make mistakes, but it is not okay to not try. Models are based on an incredibly small proportion of the whole, yet it is the whole that we expect them to accurately model. Through constructive mentoring and exposure we help them understand themselves and how they use their own strengths and abilities to explore alternatives. I believe in the young, their enthusiasm and curiosity. I believe in the old, their wisdom and intuitive ways. By being strategic in how we mentor, the old offer the young geologists a great opportunity to leverage off technology for better managed resources in the future. ^ "Decline in Education and the End of the Wesf AIG News August 2007
Sedimentary Uranium in the Frome Embayment, South Australia: A case history of the first discoveries, 1967-1974 Barry J. Cooper
^Coombes Capability
Primary Industries & Resources South Australia GPO Box 1671, Adelaide SA 5001 (cooper.barry@saugov.sa.gov.au)
As we embrace the technological age, with data and information more freely available, the value we extract from depends on our capability to synthesize, scrutinize and analyse data. And the basis of this capabiHty is a sound foundation in both logic and imagination. However, our schooling system is disappointing when we realise children as young as six are taught mathematics with calculators instead of a hands-on, tactile approach to help them build their logic and intuition. This shortcoming in the system is evident in young geologists who don't understand fractions or don't know their times tables. Dr Mike Alder from UWA's Department of Mathematics and Statistics bemoans a generation incapable of thinking and having "no capacity to reason" \
South Australia's first uranium explorers focussed on "granite country" and sedimentary uranium was generally ignored. In 1967, the USbased Kerr McGee Corporation secured exploration acreage and undertook a promising programme of non-cored drilling for uranium with down hole logging of Cenozoic sediments. The response from local geologists was quick. The Petromin group, which held exploration tenements over Mount Painter crystalline rocks, secured acreage in April 1968 over the adjacent Frome Embayment. An aerial survey, rapidly followed by pattern drilling, resulted in the Beverley uranium discovery in November 1969. Further sedimentary uranium exploration success was forthcoming via Eric Rudd, University continued next page... Australian Earth Sciences Convention 2008
73
74
ABSTRACTS alphabetically by syrriame of presenting author of Adelaide and the Minad-Teton JV. For all groups interaction with US companies proved crucial. Rudd commenced exploration in 1969 assessing the Mesozoic/Cenozoic succession. He reexamined water well information and collected new water samples for radioactivity checking. Petroleum aeromagnetics, were reviewed to determine basement highs and palaeodrainage channels. Rudd was exploring for "fronts in the sands between oxidised and unoxidised areas" thus appreciating the 'roll front model' developed by US explorers. His effort led to the discovery of the Gould's Dam deposit in November 1974. Carpentaria Exploration determined anomalous sedimentary uranium at end 1971, adjacent to the Olary region. In September 1972, they arranged a JV with Minad-Teton. Within two months, Minad determined economic uranium along edges of a buried palaeo-channel. Alteration characteristics, contained radioactivity and basal sand thickness were critical success criteria. With a further JV, Minad confirmed the Honeymoon deposit. The Geological Survey played a role in sedimentary uranium exploration. Field mapping of the Frome Embayment began in 1970/1971 with publication of the first map sheet in 1975. In 1972, drilling elucidated the stratigraphy, whilst experimental ground geophysics (gravity, resistivity and magnetics) was completed that assisted palaeochannel determination. Age-determinations, using palynology, were also undertaken.
Next generation mineral mapping in Queensland: Another piece to the precompetitive geoscience data puzzle. Tom Cudahy^ Mai Jones-, Matilda Thomass^ Carsten Laukamp"^, Peter Caccetta^ Mike Caccetta\ Rob Hewson\ Mike Verrall and Andrew Rodger ^ CSIRO Exploration and Mining, Australian Resources Research Centre, PO Box 1130, Bentley, WA 6102, Australia; (Thomas.Cudahy@csiro.au) ^ Geological Survey of Queensland, 80 Meiers Road, Indooroopilly, Queensland, 4068, Australia (MalJones@dme. qld.gov. au) ^ Geoscience Australia, GPO Box 378, Canberra, ACT, Australia, 2601 (Matilda.Thomas@ga.gov.au) James Cook University, Economic Geology Research Unit, Townsville, QLD 4811, Australia (Carsten.Laukamp@jcu. edu. au) James Cook University, Economic Geology Research Unit, Townsville, QLD 4811, Australia (Carsten.Laukamp@jcu. edu. au) ^ CSIRO Mathematics and Information Sciences, Private Bag No.5, Wembley, WA, 6913, Australia (Peter. Caccetta@csiro. au). Next Generation Mineral Mapping (NGMM) is a CSIRO "Minerals Down Under" initiative aimed at developing spectral sensing capabilities in collaboration with the government geological agencies across Australia for delivering a new range Australian Earth Sciences Convention 2008
of pre-competitive geoscience information at low cost to the resources industry. The vision is a complete suite of web-accessible, seamless, accurate maps of mineral abundances and mineral physicochemistries of the Australian continent at high spatial resolution (up to 1:25,000 scale), that can be used effectively by geoscientists. This requires suitable: - Airborne and satellite hyperspectral imaging systems that capture the full complement of spectral-mineralogy (visible to thermal infrared wavelengths); - Methods and systems for handling, calibrating and processing large volumes (Terabytes) of multi-scene imagery; - Web-based delivery tools/systems; - Models that relate spectral mineralogy to geological (and environmental) processes. As a step towards achieving this vision, the 2 year project was established in July 2006 and involved: the collection of 25000 km^ of airborne HyMap imagery (--250 flight-lines at 5m pixel resolution); over 100 ASTER scenes; and associated ground and laboratory validation data collected along major structural/geological corridors across Queensland. Specific questions asked of these data include: - Can cover rocks/materials (Palaeozoic, Mesozoic, Cainozoic and recent) be separated from Proterozoic rocks? - Can regional metamorphic zonation be mapped using illite crystallinity? and - Can fluid pathways and related akeration mineralogy associated with various styles of economic mineral occurrences be identified and mapped, especially along the major faults of the region (e.g. Cloncurry, Pilgrim and Termite Range Faults)?
Rupture Characteristics of Recent Tsunamigenic Earthquakes in Australasia, Estimated from Seismic and Sea Level Data. Phil Cummins\ Toshitaka Baba^ Hong Kie Thio^ ^ Geoscience Australia, GPO Box 378, Canberra, ACT2601, Australia (alanna.simpson@ga.gov.au) ^ Japan Agency for Marine-Earth Science and Technology Center, Yokosuka, Kanagawa, 237-0061 Japan (babat@jamstec.go.jp) ^ URS Corporation, 566 El Dorad St, Pasadena, CA 91101, USA (Hong_Kie_Thio@URSCorp.com) Since the 2004 Sumatra-Andaman earthquake and Indian Ocean Tsunami, there has been an increase both in the frequency of large earthquakes, and in the data for monitoring the seismic and sea level disturbances associated with them, especially in the Australasian region. The increased number of high-quality recordings available for these large
ABSTRACTS alphabeticaffy by surname of presenting author
earthquakes provides an important opportunity to assess methods for rapid determination of their source properties, which potentially could be used to support tsunami warning systems. In this presentation we will consider how well the available data allow us to characterise the rupture of a earthquake, consider how rapidly this could be done, and assess how well the resulting models can be used to predict far-field tsunami waveforms. The earthquakes considered include the Tonga and Java earthquakes of 2006 (Mw=8.0 and 7.7, respectively), the earthquakes in the Kuriles Islands in 2006 and 2007 (Mw=8.3 and 8.1, respectively), and the 2007 earthquakes in the Solomon Islands and off Sumatra (Mw=8.1, 8.4 and 7.9, respectively). We also discuss some of the important implications the rupture models obtained for these earthquakes have for earthquake and tsunami hazard in the Australasia region. These implications include the possible need to re-consider the maximum credible size of megathrust earthquakes in the SW Pacific subduction zones, and the potential for triggering of further large earthquakes in the Indonesian subduction zone.
The role of geoscience in developing the Indian Ocean Tsunami Warning System Jane Cunneen^ ^ Intergovernmental Oceanographic Commission of UNESCO, PO Box 1370, West Perth, WA, Australia 6872, email:].cunneen@unesco.org The Indian Ocean Tsunami Warning System is being developed by 28 countries around the Indian Ocean, under the coordination of the Intergovernmental Oceanographic Commission of UNESCO. The technical aspects of the system include deployment of instruments to measure seismic activity and sea level, numerical modelling of tsunami wave propagation, tsunami hazard and risk assessments. Geoscience research plays an important role in developing the tsunami warning system, both in earthquake monitoring and also in identifying the effects of previous tsunamis in the region. A good understanding of tsunami source regions and frequency is crucial for hazard and risk assessments. However, little is known about the historic frequency or magnitude of tsunamis. Palaeotsunami research and other palaeoseismic techniques have proven useful in identifying evidence of tsunamis in the geologic record, and current research is focused on the eastern Indian Ocean region. The two sources of large tsunamis in the Indian Ocean are the Sumatra/Java subduction zone in Indonesia and the Makran subduction zone in the Arabian Sea. While recent palaeotsunami and palaeoseismology research has focused on the Sumatra subduction zone, the frequency of tsunami
events in the Makran region is almost completely unknown, with only one documented tsunami occurring in 1945. Tsunamis from the Makran source zone would have an impact on the coasts of Oman, Iran and Pakistan, as well as the east coast of Africa. A field program has been planned to search for sedimentological evidence of tsunamis generated in the Makran source zone. An international team of experts will visit key sites in northern Oman and the south coast of Iran and Pakistan to help better define the tsunami risk to the region.
Granulites in the Northern Gawler Craton: the high temperature record of Mesoproterozoic crustal thickening.
Kathryn Cutts^ Martin H a n d ^ Dave K e l s e y , Justin Payne ^ & Karin Barovich^ ^ Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia, (kathryn. cutts@adelaide. edu. au) Granulites from Coober Pedy and Mabel Creek Ridges (CPR, MCR respectively) in the Gawler Craton separate the Northern Proterozoic terranes from the SDuthern Archaean core of the Gawler Craton. The current model for the formation of the CPR and MCR involves nappes and foldthrust structures of Mesoproterozoic age that verge southwards onto the Late-Archaean to early Palaeoproterozoic core of the Gawler craton. This study investigates the temporal metamorphic evolution of the CPR and MCR in order to provide constraints on the particular paths associated with Mesoproterozoic crustal thickening. Metapelites from the MCR contain an early mineral assemblage of biotite + sillimanite + ilmenite + quartz that occurs as inclusions within garnet poikiloblasts. The final assemblage is garnet + cordierite + biotite + sillimanite + ilmenite + quartz where cordierite has grown at the expense of the garnet-sillimanite association. Based on the petrology, these samples reached maximum P-T conditions of approximately 6 kbar and 750-800 ""C during a clockwise P-revolufion. LA-ICPMS monazite data from one MCR sample provide ages of ca. 1580 Ma for monazite armoured within garnet grains and ca. 1560 Ma for monazites located within the matrix. These metamorphic ages are coincident with the later stages of the voluminous Hiltaba Suite magmafism which dominates the central Gawler Craton. The ca. 1580 Ma metamorphic ages also coincide with granulite-grade metamorphismin the central eastern Gawler Craton, and in the basement hliers of the Barossa Complex. Viewed regionally and in the context of the clockwise P-T evolution and nappe stacking, the MCR and CPR probably forms part of continued next page... Australian Earth Sciences Convention 2008
75
76 ABSTRACTS aiphabeticatly by sumame of presenting author
a large system of early Mesoproterozoic, roughly NS directed shortening in the southern Australian Proterozoic. This shortening system encompasses the Olarian Orogeny {ca. 1600 Ma) to the east and systematically youngs westwards toward the western Gawler Craton.
The University of the Sea and the benefits to learning of active participation in a research cruise.
An integrated tectonic framework of the Eastern Goldfields Superterrane
^ Department of Earth and Planetary Sciences, Macquarie University, NSW 2109 (kdadd@els. mq. edu. au) ^ UNEP Shelf Programme Regional Office, School of Geoscience, University of Sydney, NSW 2006 (ebaker@mail. usyd. edu. au)
K. Czamota^ R.S. Blewett\ D.C. Champion^ P. Henson\ B. Goscombe^, K.F. Cassidy^ ^ Geoscience Australia GPO Box 378, Canberra ACT2601 Australia, (karolczarnota@ga.gov.au) ^ pmd'^CRC, c/o Integrated Terrane Analysis, 18 Cambridge Rd. Aldgate SA 5154 , Australia ^ Rubicon Resources PO Box 534, West Perth WA 6872 Australia Mineral deposits are the products of largescale tectonic processes. Over the last decade there have been significant advances in our understanding of Yilgam Craton, Eastern Goldfields Superterrane (EGST): stratigraphy; magmatism; deformation; metamorphism; and timing of mineralisation, through various AMIRA and pmd'^CRC projects. The integration of these disciplines, largely aided through advances in geochronology, has enabled a holistic view of the tectonic history of the EGST, thereby providing a geodynamic context for its mineralisation. A significant advance has been the recognition of a -2.81 Ga rifting event off the eastern margin of the Youanmi Terrane which set up the NNW trending architecture of the EGST, as expressed in the sNd model age map of the Yilgam. This rifting event was then inverted during the subduction-dominated deposition of the 2.7152.67 Ga EGST volcanic stratigraphy and emplacement of voluminous TTG magmatism, which resulted in magmatic thickening of the crust. Volcanism was terminated by a ~5 Ma pulse of ENE contraction triggering lithospheric and lower crustal delamination associated with mid-orogenic extension. The lack of ultra-high pressure and the presence of high geothermal gradients precludes this event from recording a continent-continent collision. Mid-orogenic extension resulted in the introduction of metasomatised mantle melts (Maficgranites and Syenites), deposition of late-stage siliciclastic basins (which record anticlockwise PT/ paths) and the start of significant economic gold mineralisation in the EGST. The delamination associated with this event resulted in significant heat input into the base of the crust, which eventually led to the emplacement of the Low-Ca (crustal melt) granites and cratonisation of the EGST. Major Au mineralisation postdates delamination, associated with renewed compressiontranspression and the development of steep sinistral and later dextral (syn Low-Ca granites) strike-slip faults.
Australian Earth Sciences Convention 2008
Kelsie Dadd^ and Elaine Baker^
The University of the Sea is a partnership between the Intergovernmental Oceanographic Commission of UNESCO, the University of Sydney, the Australian National University, the University of New South Wales, Macquarie University, the University of Technology Sydney, the University of Tokyo, the Korean Ocean Research and Development Institute, Tongji University China, the Partnership for Observation of the Global Q e a n s Canada, the National Institute of Oceanography Goa and the Indonesian Research Centre for Marine Technology. Through this program, young local scholars are able to address specific regional problems through a program of targeted research on marine issues while working with senior researchers from the region. The UoS program, places the students in the role of a researcher, and is thus a form of experiential learning. This type of active student engagement is often seen as the most effective way for students to learn and recognises that learning takes place in settings other than within formal institutions. Experiential learning is about both personal and practical involvement in the learning situation. Personal involvement leads to the development of a number of generic skills including empowerment, and becoming conscious of ones needs and desires. Practical involvement leads to greater student motivation, provides students with new oceanographic and scientific skills and, through active involvement, instils a deeper understanding of the subject content. Participation in research cruises places the student in a learning environment that engages their full attention. The student must make their own decisions and experience the results of these decisbns. The program inspires not only the student involved but others they come in contact with at their home institution. The UoS has operated since 2004 and research cruises have investigated problems in the Coral, Arafura and Tasman Seas. The research problems have ranged from sea level change to gas hydrates and benthic habitats.
ABSTRACTS 77 aiphabatfcally by surname of presenting author
Infrastructure Planning Contamination Management
and
Malcolm Dale Parsons Brinckerhoff, GPO 5394 Sydney, NSW, 2001, Australia, (mdale@pb.com.au) Geoscience has long been part of major infrastructure planning for roads, railways, pipelines and tunnels through the engineering geological and geotechnical engineering investigation processes. Contamination management, however is often an afterthought resulting in significant cost increases. Increasing contamination management is, however, becoming part of the mainstream planning process and is likely to include assessment and remediation of contaminated sites, acid sulfate soils and acidic/sulfidic rocks, water, waste and spoil management, and demolition management. Many of these investigations use geological based investigation to aid with route alignment, property purchase, soil re-use and contingency management. Contamination management may include preliminary planning where the potential for contamination is identified to highlight the need for preventative or corrective environmental works. This may include desktop studies along the planned alignment to identify major sources of contamination such as service stations, landfills, previous fill material (e.g. rail ballast) or buildings containing asbestos containing materials. This can allow for the preparation of various contamination management plans to gain development consent. During the construction stages, geological and contamination input can ensure that excavation and imported fill materials are suitable for their intended use; provide additional safety measures to protect worker and public health and safety; and recommend treatment and appropriate storage options for potentially contaminated materials (including acid sulfate soils); undertake sampling of sediment and water in retention ponds to ensure appropriate quality for discharge and management of ingress of potentially contaminated water. Post construction investigations may include decommissioning of fuel facilities, works depots and returning the land to its pre-existing condition as part of the Condition of Consent. Major infrastructure projects may have surplus fill materials from tunnel construction or road building which may need to be recycled, remediated or disposed of according to its material/waste classification The paper will present examples of major infrastructure planning and construction for roads, railways and tunnels in eastern Australia that demonstrating the role of "geoscience in the service of society" as a key measure in the protection of the environment and health and safety and the management of soil and water including the sustainable re-use of excavation materials.
Carbon Dioxide Storage Sites: From Prospects to Pilots. Tess Dance ^ ^The Cooperative Research Centre for Greenhouse Gas Technologies CO2CRC and CSIRO. Australian Resources Research Centre, Technology Park, Kensington, WA 6151 (Tess.dance@csiro.au) The burning of fossil fuels for energy is a major source of carbon dioxide. In Australia nearly 214 MMT of CO2 is emitted from stationary sources every year in the energy sector (source: National Greenhouse Gas Inventory 2005). To meet Kyoto targets for CO2 emissions will require increased use of renewable energy, greater energy efficiency, fuel switching and increased carbon sequestration (the capture and storage of carbon dioxide and other greenhouse gases that would otherwise be emitted to the atmosphere), and particularly geological storage ofC02. A national assessment of Australian sedimentary basins identified 64 sites that have suitable characteristics for safe, sustainable CO2 storage (the GEODISC project 1998-2002). Consequently several of these sites, proximal to large stationary sources, have been further examined to determine storage capacity, injectivity, and containment; and also to examine the risks of injected CO2 to natural resources. Studies, such as the assessment of the Southern Perth Basin, relied mainly on non-proprietary data from petroleum exploration, geological surveys, and groundwater databases. This, in effect, has been a prospecting exercise, at the regional scale, providing information to government and industry groups about the most suitable locations for future carbon capture and storage projects. With the establishment of Australia's first geo-sequestration demonstration pilot project, onshore in the Otway Basin, Victoria, it was necessary to elevate this "prospecf to a fully characterised site prior to any injection of CO2. This involved the acquisition of new down-hole data, surface seismic, core, and formation tests. Greater understanding of the geology at reservoir scale meant reduced uncertainty in reservoir simulations and design of a better informed monitoring programme. This paper compares the methodology for geological characterisation of CO2 storage sites at two different scales, regional and local, using examples from the Southern Perth Basin in Western Australia, and the C02CRC Otway Project.
Australian Earth Sciences Convention 2008
78 ABSTRACTS alphabetically by
surname of presenting author
Tectonics and volcanism associated with the propagation of backarc spreading and associated rifting of an island arc: An example from the southeast margin of the North Fiji Basin Leonid V. DanyushevskV, Trevor Falloon^, Anthony J. Crawford^
Katarina David^
J.
^ CODES, ARC Centre of Excellence of Ore Deposits, University of Tasmania, PB 79, Hobart, TAS 7001 (ldan@utas.edu.au) The North Fiji backarc basin (NFB) began opening - 1 2 Ma in response to subduction reversal along the Vanuatu section of the Proto-Vitiaz arc. The triangular shape of the basin reflects ongoing (since ~5 Ma) southward propagation of the backarc spreading centre in response to westward roll-back of the Vanuatu trench and eastward roll-back of the Tonga trench. The southeast boundary of the Basin is formed by the submarine Hunter Ridge which is an inactive island arc. The southern tip of the North Fiji backarc basin (22 174 ""E) is a volcanically active submarine boundary between the backarc basin spreading centre and the Vanuatu trench and Hunter Ridge. This area has been mapped and sampled during the SSlO/2004, SS08/2006 and SS08/2008 voyages of the R/V "Southern Surveyor". Multi-beam seafloor bathymetry acquired during the voyages reveals that the processes occurring during southward propagation of the backarc basin involve sequential formation of 50100 km long rift zones that split the crust of the Hunter Ridge along its strike. Initially such rift zones form as narrow (2-3 km wide) well-defined grabens with incipient magmatic activity. Then the graben widens to form a robust magmatic rift with clear volcanic centres and incipient spreading. Finally, the rift undergoes rotation and evolves into a N-S aligned robust spreading segment. Volcanic Dcks erupted during rifting within each segment include a large spectrum of subduction-related magma compositions from backarc basin basalts to boninites, calc-alkaline basaks and high-Mg adakites. All magma series have very primitive, high MgO endmembers. There is clear petrographic and geochemical evidence for extensive mixing between high-Mg adakitic and backarc basin magmas in this area, which results in formation of primitive magmas with typical calcalkaline and boninitic affinities. This mixing process we beheve is applicable to the genesis of calcalkaline magmas world-wide.. We will present detailed geology and geochemistry of all volcanic rocks from this region and discuss their origin.
Austraiian Earth Sciences Convention 2008
Looking for mine water supply in the area of limited water allocation (Boggabri Coal, NSW)
^ Parsons Brinckerhoff, GPO Box 5394, NSW2000, Australia;(kdavid@pb.com.au)
Sydney,
Boggabri Coal Mine is located in the Gunnedah Basin, northeast of Boggabri township, in the Namoi River Valley, NSW. The regional geology encompassing the mine comprises Permian and Quaternary/Tertiary alluvial sediments unconformably overlying early Permian volcanic deposits. To the west of the mine site the quaternary alluvial sediments of the Namoi Valley form a thick sheet. Available groundwater information suggests that two main aquifer systems exist in the area, Namoi Valley alluvium and fractured rock. Alluvial aquifer is well defined and has been a subject of many studies, however the fractured aquifer characteristics are less known and the available literature is mainly related to locations where mining is occurring. In addition, the relationship between the alluvial and fractured rock aquifer is unknown. Several prior studies have explored the option of water supply to the mine by extracting shallow groundwater from Namoi alluvium. However with limited allocation available, the mine looked at water supply from its own development operations, i.e. from the fractured rock aquifer. Locally, within the fractured rock aquifer the coal seams represent hydraulically most conductive unit. This aquifer is confined to semi-confined bounded below by fresh volcanic bedrock and above by low permeability sandstones and conglomerates. Residual volcanic soils (weathered profile) to the southwest of the mine lease provide the connection between the coal seam aquifers and the alluvium associated with ephemeral creeks and Namoi River. Installation of piezometers, historical and recent water level and quality monitoring, including well defined geology model have assisted in understanding of fractured aquifer. The study finds that the Permian sedimentary sequence and the fractured rock aquifer (where the mine is located) are isolated from the Namoi alluvium by underlying Boggabri volcanics. The fractured rock aquifer can to some extent provide water for mine supply. However, any effect from mining on groundwater will be localized and mostly confined to the mine lease area.
ABSTRACTS alphabetically by surname of presenting author
The Early Mantle: Depletion, Plates, Resurfacing Episodes and Isotopes Geoffrey F. Davies^ ^ Research School of Earth Sciences, Australian National University, Canberra ACT 0200 (Geoff.Davies@anu. edu. au) Numerical models of early mantle dynamics reveal several important differences from the present mantle. The early mantle would have been 200300°C hotter than the present mantle, its viscosity around 100 times lower, and mantle dynamics consequently more vigorous. Mantle melting would have generated mafic crustal material. Difference 1: the upper mantle would have been strongly depleted of mafic -composition component. Subducted mafic material is denser than average mantle through most of the depth of the mantle, and the lower viscosity would allow it to settle out of the upper mantle (but not the more viscous lower mantle) despite the stirring of more vigorous mantle convection. The upper mantle depletion is consistent with Nd and Hf isotopic evidence for a strong depletion of mantle sources of the earliest crust. Difference 2: the depleted upper mantle would generate only 2-4 km of oceanic-type crust, despite its higher temperature (compared with 30 km from fertile mantle). This would facilitate subduction and thus possibly plate tectonics. Difference 3: the mantle would have stratified episodically. Mafic material is buoyant between 660 km and 750 km depth and would tend to accumulate there. This would form a barrier that thin early plates could not penetrate, resulting in layered mantle convection. Every 100-150 Ma there would be a breakthrough and overturn, bringing hot, fertile material up from the lower mantle and generating a burst of magmatism sufficient to resurface the Earth with 10-20 km of mafic crust. As the mantle cools, plates eventually become thick enough to break up the basalt barrier after 1.5-2 Ga and no further layering occurs in the models. Such episodes may be related to bursts of continental crust generation. Evidence of early melting events may also be preserved in the deep mantle and manifest in mantle helium isotopes.
Geology and Resources of New Guinea. Hugh Davies Mineral Resources Authority, P.O. Box 414, University NCD Papua New Guinea, (lidavies@mra.gov.pg) The southern half of the island of New Guinea comprises Australian Precambrian and Palaeozoic craton overlain by Paleozoic (western half only).
Mesozoic and Cenozoic sediments. The sedimentary section is up to 16 km thick in the west (in Indonesian Papua) and 45 km thick in the east (in Papua New Guinea). The northern margin of the craton forms a basement-involved foreland fold and thrust belt. The northern half of the island comprises accreted terranes of marine volcanic and continental character, the youngest of which are a volcanic arc terrane of Oligo-Miocene age and a newly recognized seafloor basalt terrane of Pliocene age. Northeast of New Guinea are the islands of the Bismarck Archipelago and of the Solomons chain which comprise arc volcanic rocks of Early Cenozoic and younger age, and in the Solomons some oceanic basalt - the uplifted margin of the Ontong Java Plateau - and metamorphic rocks. Sea floor spreading is active in the Bismarck Sea and the Woodlark Basin. Subduction is active on the northern margin of the Solomon Sea (New BritainMakira Trench) and along part of the north coast of New Guinea (New Guinea Trench) and slowly active on the outer margin of the New Guinea and Solomon islands (Manus-Kilinailau trench). Major mineral deposits include large scale copper-gold porphyry mineralization associated with Plio-Quaternary intrusives in the fold and thrust belt (Grasberg, Ok Tedi), and with Late Miocene intrusives in terranes just north of the fold belt (Frieda River). Meso- and epithermal gold mineralization at Porgera also is in the fold-and-thrust belt. Gold at Lihir, northeast of New Ireland, was deposited in the heart of a Plio-Quaternary volcano. There are hydrothermal sea floor deposits of gold with base metal sulfides in the eastern Bismarck Sea and commercial oil and gas in the New Guinea foieland and fold and thrust belt.
The National Geochemical Survey of Australia: Overview and progress Patrice de Caritat^
^ Geoscience Australia, GPO Box 378, Canberra ACT 2601, Australia (Patrice.deCaritat@ga.gov.au) Geoscience Australia, in collaboration with the geoscience agencies in all States and the Northern Territory, has recently launched the National Geochemical Survey of Australia ^GSA) project. It aims to deliver internally consistent, state-of-the-art geochemical data and information spanning the entire continent, based on a common sampling medium. This data set will provide fundamental, pre-competitive information on the concentration levels and spatial distributions of chemical elements in transported regolith. The survey is based on the collection of samples of overbank or floodplain sediments at the outlet of -1400 catchments covering >90% of Australia. This gives an average sampling density of ~1 site/5500 kml Materials will be collected from 2 depths (0-10 cm and -60-70 cm) and separated into 2 size fractions (<2 mm and <75 um). Analysis of these materials, mostly by continued next page... Australian Earth Sciences Convention 2008
79
80 ABSTRACTS
alphabetically by surname of presenting author XRF and ICP-MS, will yield total and aqua regialeached concentrations for - 6 0 elements. A primary focus of the project will be applications to regional exploration programs for mineral and energy resources. As a spin-off, the data generated may also be useful for environmental management applications. The NGSA project runs from 2007 to 2011 and will deliver a publicly available geochemical database and an online geochemical atlas on the web. At the time of writing (December 2007), 20% of the sites have been sampled and sample preparation (drying, sieving, etc.) is in progress. The presentation will report on progress to July 2008. Further information on the NGSA project can be found at http://www.ga.gov.au/ngsa.
Assessment of geochemical risks of saline acid ground-water in the Western Austrahan Wheatbelt.
Landscape evolution and hydrostratigraphy control the development of dryland salinity in the southwest of Western Australia
The threat of increasing dryland salinity in the paleodrainage systems of the Western Australian (WA) Wheatbelt has led to increased use of deep open drainage systems to control shallow ground-water levels. Drains are principally constructed to recover and/or protect land from salinisation,. Many systems are about 20km in length and discharge to saline lakes, intermittent streams or floodways. Evidence of acidity associated with some shallow saline ground-waters (east of the Meckering line) has raised concerns that of drain discharges will acidify waterways and increase accumulation of trace metals. Reconnaissance surveys of groundwaters and surface waters (lakes, drains, creeklines and floodways) were carried out across the WA wheatbelt to determine geochemical risks associated with acidic saline waters. This was coupled with surveys of minerals in drain and lake environments in which acidic waters occurred. Over 80% of drying phase lakes and 56% drains in the central eastern wheatbelt (east of a line from Camamah to Dumbleyung) were found contain acidic (pH<4.5), saline (at least 40 000 mg TDS/L) waters with over half containing high concentrations of soluble iron (commonly >100mg Fe/L), aluminium (commonly >80 mg A1 /L) and, to a lesser extent, manganese (>5mg/L). Trace metals such as Pb, Cu, Zn, Ni, U and rare earth elements (La, Ce) could also occur in high concentrations (>0.5 mg/L). Similar concentrations of these elements were also found in regional groundwaters. All lakes receiving acid waters from drains were acidic, however there were also acidic lakes created by regional groundwater discharge that appeared geochemically similar to these. Minerals identified in acidic drains and lakes indicated that complex geochemical processes occur resulting in formation of: sulfidic sediments; iron (eg akaganeite, schwertmannite, jarosite) and aluminium minerals; and precipitation of a range of Na, Ca and Mg salts. These processes play a major role in influencing the mobility of acidity and trace metals in drains and lakes. Furthermore, the processes highlight key areas where practical management options can be targeted to mitigate the risks that acid drain discharge poses to surface waterways in the wheatbelt.
Javath De Silva\ Robin Smith^ ^ Department
of Water
In broad Wheatbelt valley floors of southwest Western Australia, Quaternary alluvial, colluvial and lacustrine deposits may cover Eocene and/or Pliocene sediments up to 70 m thick on basement rocks. Most palaeovalleys have an alluvial sands and gravel aquifer in the base of the palaeochannel itself with lignitic beds trending upwards into confining lacustrine (or shallow marine) clays and finally into the surficial aquifer of sands and clays, where present. Due to landscape inversion, these sediments appear high in the landscape. From 250 to 230 m AHD the confining clay layer above the palaeochannel sand is characterised by large lakes, including Lake Nunijup in the Kent River catchment, and by swamps, including Darkan Swamp in the Helena River catchment. The palaeochannel sand aquifer readily discharges saline groundwater where dissected by rivers draining to the south and west coasts. Locally unconfined between the elevations 230 to 200 m AHD, its discharge consequently sustains pools, increases the stream salinity and provides most of the salt load of the Kent River. Discharge to the Helena River sustains year-round saline flow from the same elevation range. Below 200 m AHD, the rejuvenated rivers have narrow valleys and gain less salt load from the weathered bedrocks. At 200 m, the Kent River changes direction to the south, having cut through the sediment profile to the faults and joints of the basement rocks. These characteristics invite salt storage mapping to focus on the sedimentary profiles within this elevation range as part of catchment management initiatives to address dryland salinity.
Degens, B . V \ Shand, P . ^ F i t z p a t r i c k , R . W ^ ^ R o g e r s , S . L . ^ D o u g l a s , G.B.^ G e o r g e , R J . ^ a n d L i l l i c r a p , A.^ ^Department of Water, WA., P.O. Box K822, Perth WA (brad.degens@water.wa.gov.au) ^CSIRO Land and Water, Adelaide ^Co-operative Research Centre for Landscape and Mining Environments, Kensington WA. "^CSIRO Land and Water, Perth ^Department of Agriculture and Food, WA.
ABSTRACTS 81
alphabetically by surname of presenting author
Treatment of Saline Acid Drainage in the Western Australian Wheatbelt: Field Evaluations.
Exploration for Sandstone-Type Uranium Deposits in Tertiary Palaeochannels in the South of Western AustraUa
Degens. B.P.^ and Mcintosh, K.^
Mike Dentith^^ Matt Gauci\ Stefan Gawlinski\ Margaret Newton \ Stuart Peterson\ Duncan Cowan^, Bill Peters^
^Department of Water, WA., P.O. Box K822, Perth WA. (brad.degens@water.wa.gov.au) There is increasing interest in using deep open drains and ground-water pumping to protect and/or remediate marginally salinised lands and high value assets the inland wheatbelt of WA. Implementation of such schemes, however, is commonly limited by safe, practical, cost-effective options for managing the disposal of these waters. Many saline ground-waters the paleodrainage valleys of the inland Western Australian wheatbelt are acidic and may need to be treated as part of managing the safe disposal of these waters. Acid mine and acid sulphate soil drainage treatment technologies have been adapted and evaluated to identify practical, cost-effective options that could be applied by farmers and/or landcare groups. Treatment has focused a combination of demonstrations and evaluations using locally available neutralising agents and organic materials. The effectiveness of locally available limesand (CaCOs) was demonstrated and evaluated in a range of active and passive treatment situations including lining of drains, lining of storage basins, throughflow treatment for pumping systems and dosing units. Composted treatment systems were evaluated in three passive treatment systems: a ground-water interception wall, shallow compost wetland and in-drain compost system. Limesand performance was limited by high ferrous iron concentrations, resulting in armouring, and high salinities in evaporation situations (resulting in gypsum precipitation). These could only be overcome by using increased energy (generally pumping) to increase limesand abrasion and water-limesand contact. Alternative calcium based neutralising agents (eg Ca(0H)2) were more effective in treating the waters, but required more management to avoid overdosing. Compost based treatment systems could be effective in some situations with a capacity treat a wide range of acidic waters. These systems also generally operated for the longest periods with minimal maintenance, compared with lime based systems. However, effectiveness was dependent on the organic material used in the construction of the systems. Selection of appropriate treatment systems is dependent on the duration and scale of treatment (acid load and discharge volumes).
^Epsilon Energy, Subiaco, WA (mdentith @ segs. uwa. edu. au) ^Cowan Geodata Services, Dalkeith, WA Southern Geoscience Consultants, Applecross, WA "^Centre for Exploration Targetting, School of Earth & Geographic Sciences, University of WA, Crawley, WA The sediments within the Tertiary palaeodrainage system which crosses the Archean Yilgarn Craton contain world-class uranium deposits, notably the sandstone-type Mulga Rock deposit (47,000 UsOg) and the calcrete-type Yeelirrie deposit (52,000 UsOg). The source of the uranium is the widespread Archean granitoid rocks. The uranium in its soluble hexavalent form is transported by oxygenated groundwater flowing within aquifers within the Tertiary sediments. Uranium is trapped, leading to potentially economic accumulations, by adsorption and/or precipitation from solution following reduction to its insoluble tetravalent form. In both cases organic matter facilitates uranium capture. The Tertiary succession within the palaeodrainage system contains extensive (organic-matter rich) lignite deposits. Epsilon Energy is exploring for sandstone-type uranium deposits in the Heartbreak-Balladonia area, located in the southeast of the Yilgarn Craton. The large area to be explored requires the use of geophysical methods. Airborne radiometric data show there are several uraniferous granitoids in the exploration area. Airborne electromagnetic data have successfully mapped conductive units within the Tertiary sediments and inverse modelling allows the 3D geometry of the drainage system to be established. Aeromagnetic data map basement geology and show that interpreted faults coincide with changes in the style of the palaeodrainage system. Prospective geological settings include: where broader channels, indicative of sluggish drainage and potentially stagnant (reducing) conditions, occur downstream from uraniferous granites, and where the main channel is curved and merges with tributary lower-order channels. Initial results suggest the ultra-salinity of the local groundwater prevents electrical/electromagnetic geophysical methods from mapping lithological variations within the Tertiary succession, which must be determined from drilling. Maps of the distribution of permeable sand-rich units within the palaeodrainage allow likely flow paths for uraniferous groundwater to be determined. The juxtaposition of these paths with lignitic and reduced units represent the most favourable sites for mineralisation. Australian Earth Sciences Convention 2008
82 ABSTRACTS alphalsetically by smmme of presenting author
Evidence for competing movement patterns influencing the evolution of the Sagaing-Sumatra wrench fault system Abhiiit Deonath^ Gordon Lister^ and Mamie Forster^ ^ Research School of Earth Sciences, The Australian National University, Canberra, 0200, (abhijit. deonath @ anu. edu. au) (gordon.lister@anu.edu.au) (marnie.forster@anu.edu.au) Here we examine the evolution of the Sumatra-Sagaing fault system to provide information as to the geodynamic context of seismogenic behavior in SE Asia. The Myanmar-Sumatra region is examined using Shuttle Radar Topography Mission (SRTM) datasets to infer basic characteristics of the evolution of this wrench fault system over -3800 km of its lateral extent. Our analysis shows that whereas the wrench system has an approximate small circle geometry, there are significant deviations that potentially maybe caused by flow of the crust related to escape of material from Tibet, and/or arc normal flow (with a westward component) driven by gravitational potential energy and/or the effects of roll-back of the Indian and Australian slabs. In the south and east, the wrench system crosses the Sunda Strait, from Java, into Sumatra. In northern Sumatra, the wrench system is characterized by westward-stepping left-lateral horsetail splays, and this causes local transpression. In the Andaman Sea, the wrench develops eastward-stepping extensional zones, which have developed into a transtensional ocean basin. In northern Myanmar, now known as the Sagaing fault system, the wrench is again deflected, apparently in response to orthogonal lateral flow, in this case related to westward tectonic escape of the Myanmar crust. Further north the Sumatra-Sagaing wrench system ends. This occurs to the west of Namche Barwa, which is an extensional gneiss dome related to the termination of the right-lateral system. The movement picture overall is consistent with a right-lateral wrench system affected by arc normal outward flow of the crust. The structural geology therefore reflects the effect of arc normal flow acting in competition with the movement of plates and microplates in the region. The results shed further light on the enigma of 'rigid' microplates versus behavior of an orogen better approximated by flow of a viscous fluid.
Australian Earth Sciences Convention 2008
A Perfect Sulphide Storm at Mt Isa G.M.Derrick ^ 'G.M Derrick Geology, PO Box 184 Corinda Q 4075 (geoffd@powerup.com.au) A perfect sulphide storm of Pb-Zn-Ag sedex mineralisation occurred at Mt Isa at 1655±10 Ma. forming two giant orebodies at Isamine and George Fisher containing 150mt @ 6% Pb, 7% Zn, 150g/t Ag and 130mt @ 5% Pb, 9.5% Zn, 106g/t Ag respectively. These orebodies formed in the waning stages of an extended 140Ma period of episodic rifting, accompanied by asymmetric tilting of fault blocks, growth faulting and formation of permissive dolomitic, carbonaceous and pyritic stratigraphy. Recent research has focussed on basinal frameworks, fluid flow modelling and subsurface architecture in the Lawn Hill platfonn north of Mt Isa, as explorers contend with deeply buried target zones. Despite this work, the specific features controlling the giant Isa-George Fisher deposits remain enigmatic, partly due to a complex deformational history. An often overlooked component of sedex mineralisation is the requirement for suitable source rocks in deep footwall stratigraphy from which PbZn can be extracted by basinal brines. Rapid burial to 10km or so of immature felsdpar-rich clastic and volcaniclastic source rocks, without formation of porosity-occluding silica overgrowths, is essential (Polito et al., 2006, Econ. GeoL, v. 101, pi 159). Footwall stratigraphy at Mt Isa dated 1790 to 1760Ma contains large volumes (+1000km^) of such lithology in the lower Mt Guide Quartzite and it's metamorphosed equivalent, the May Downs Gneiss, which formed a tabular wedge to 800m thick deposited westwards of the eastern rift edge. Removal of the effects of the 1600-1500Ma Isan Orogeny shows the following: 1. The syn-rift Haslingden Group formed in easttapering half-grabens containing thick units of basal immature clastics. 2. Present-day Paroo and Crystallena Faults formed a major normal fault system along the western edge of the half-grabens. 3. Mt Isa Group formed 1660 to 1650Ma in restricted basins above 1710-1690Ma asymetrically tilted blocks bounded by active growth fauhs. 4. Pb-Zn mineralisation was emplaced during diagenesis in a perfect sulphide storm at about 1655Ma. 5. Key to further discovery includes recognition of sequences of feldspar-rich units deep below receptive basins in modem seismic profiling.
ABSTRACTS aiphabeticafly by surname of presenting author
Integrated isotope and trace element analyses of detrital minerals from the Frankland River (SW Australia)
The Simulation of the Quantitative Estimation of the Influence of Processes and Products on the Environment
Bruno Dhuime^ Chris Hawkesworth^ Craig Storey^, Peter A. Cawood^
Tatjana Dovbysheva. Anne Yasko
^Department of Earth Sciences, University of Bristol, Bristol, BS8 IRJ, UK (B.Dhuime@hristolac.uk) School of Earth and Geographical Sciences, University of Western Australia, Perth, Australia (p. cawood@info. curtin. edu. au) The juvenile rocks from various continental
segments show striking peaks in igneous activity at
-1.9 and -1.2-1.0 Ga, interpreted as periods of accelerated crust formation (Condie, 1998, EPSL, v. 163). However episodic crust generation remains difficult to reconcile with the smooth evolution curves inferred from the Nd isotopes in shales (Allegre and Rousseau, 1984, EPSL, v. 67) and arguably with the continuous nature of subductionrelated magmatism. An alternative is that periodicity in igneous activity reflects rapid crustal generation in response to the emplacement of mantle 'superplumes'. A major difficulty is in interpreting the implications of model source ages from Hf in zircon and Nd in shales. Detrital zircons from the upstream (northern) part of the Frankland River that flows through the Yilgam craton yield unimodal -2.7 Ga UPb ages, and this Yilgarn signature contribution decreases from -98 to 25% in the grains from the downstream part of the river, which flows through the ArcheanMesoproterozoic Albany-Fraser orogen (Cawood et al., 2003, EPSL, v. 210). The sediments of the Frankland River therefore provide an excellent opportunity to investigate the radiogenic isotope record in the sedimentary record in an area of known source rocks, and hence explore the strengths and limitations in using sediments to constrain models fro the evolution of the continental crust. We present a comparative study of Nd isotopes on whole-rocks (shales) and in situ Hf (on zircon) and Nd (on titanite) analyses on accessory phases. The TDM Nd and Hf model ages constrain the crustal residence ages, i.e. the time since juvenile crust was extracted from the mantle, and they are used to further constrain the relative contributions from different source rocks, in different minerals, and for the different isotope systems. The Frankland River sediments also provide insights on the full record of crustal evolution in the Yilgarn area, which has broader implications for models of the evolution of the continental crust.
International Humanitarian Economy Institute, Str. Gudro 23-20, Minsk 220121, Belarus, (tdovbysheva@bntu. by) In result of the technogenic activity of the human there is an environmental contamination, deterioration of the natural environment concerning normative parameters. At forecasting possible negative and dangerous environmental impact it is necessary to take into account: - The quantity of dangerous and harmful materials - The condition of their storage - The type of these material - The depth of probable pollution - The area of potential pollution - The duration of activity of dangerous materials - The time of liquidation of consequences of negative and dangerous action. In turn at forecasting possible (probable) negative and dangerous influence for an environment the big value in addition to set forth above factors has such factor, as the economic mechanism of management of influences on an environment. This factor is defined as total influence of all set forth factors. However wide (broad) use of economic methods managing the environmental impacts of processes and product on environment restrains absence of the common methods of a quantitative estimation of ecological danger. One of the tasks of the informatics is a development of models of potentially accidents and development of the recommendations for warning and liquidations of consequences. The quantitative estimation of ecological danger is necessary for development of such model. The calculation in relative parameters enables to present in a dimensionless kind a level of ecological danger (including actual damage and expected risk) from technogenic enterprises. The paper presents a method of a quantitative estimation of ecological danger influence difference pollution on an environment. Two models are considered in dependence of a degree of impact of separate pollutants on the common impurity of territory: - Model of equivalent factors a - Model of inadequate factors. In the paper the factors which are necessary for taking into account are submitted. Major factors of this paper are interconnected among themselves. One of them may be a part of another. So, the factor type of dangerous and harmful waste is one of making parts continued next page.. Australian Earth Sciences Convention 2008
83
84
ABSTRACTS alphabetically by surname of presenting author
of the following factors: the depth of probable pollution, the condition of their storage, the area of potential pollution, the time of liquidation of consequences of negative and dangerous action, the duration of activity of dangerous waste.
Taking Geology to the Geotourism and Geoparks
Public:
Ross Dowling^
Secondary minerals from the Braeside lead field, Pilbara, Western Australia. Elena A. Hancock^ Peter J. Downes\ Alex W. R. Bevan^ ^Department of Earth and Planetary Sciences, Western Australian Museum, Locked Bag 49, Welshpool DC, Western Australia, 6986. (peter. downes@museum. wa.gov. au, E.Hancock@bigpond.com)
^ Edith Cowan University, School of Marketing Australia is integrally associated with its geological resources but in recent times there has been an awakening of using them for tourism rather than exploitation. The country has many sites of geological significance and indeed the major attraction is Uluru (Ayers Rock) in the middle of this arid continent. Whereas most geotourism sites are located in either National Park or World Heritage sites, last year the first National Geopark 'Kanawinka' was established across two states in the south-east corner of the country. At 23 0000 sq km, it is the largest geopark in the world. Reflecting the rise in understanding of the importance of geological areas, more and more people have become interested in seeing and learning about their geological heritage. This has given rise to the emergence of 'Geotourism', that is, sustainable tourism with a primary focus on experiencing the earth's geological features in such a way that fosters environmental and cultural understanding, appreciation and conservation. In Western Australia, the vast relatively empty western third of the continent, the Department of Environment and Conservation has been long involved in the interpretation of its many geological sites. This presentation will describe Australia's efforts to foster geotourism through a case study of Western Australia. A number of geotourism sites will be discussed along with examples of 'best practice' interpretive signs and booklets which introduce tourists to the geology and landforms of the regions in the state. The State has contributed much to geotourism. Two academics have edited the world's first book on Geotourism (Elsevier, 2006) and in August 2008 the Inaugural Global Geotourism Conference will be held in Perth, the capital of Western Australia. Both contributions to geotourism will be discussed and their relevance placed in the global context.
Australian Earth Sciences Convention 2008
The oxidised zones of four small Pb deposits (Devons Cut, Ragged Hills, Moxom Well, Koongalin Hill) in the Braeside lead field, east Pilbara, Western Australia, contain complex assemblages of Pb, Zn, Cu, V and Ag-bearing secondary minerals. These minerals include cerussite, hemimorphite, chalcocitc, coronadite, brochantite, malachite, pyromorphite, chrysocolla, anglesite, smithsonite, cinnabar, acanthite, vanadinite, descloizite, mottramite, hydrozincite, linarite, caledonite, otavite, rosasite and plattnerite. Some insight into the prevailing chemical conditions in the oxidised zone during the weathering of the orebodies is provided by these mineral assemblages. The Neoarchaean primary Pb mineralisation (galena ± pyrite, sphalerite, chalcopyrite, bomite) in the Braeside field is hosted by a low-T, low-P siliceous vein system that cuts the Kylena Basalt and overlying Maddina Basah formations of the Fortescue Group. The quartz vein systems in the Gregory Range are interpreted as epithermal, lowsulphidation type deposits formed in active geothermal systems dominated by groundwater. The occurrence of otavite (CdCOs) at Devons Cut appears to be only the second reported in Australia after Broken Hill, NSW, and probably is indicative of alkaline conditions in mineralising groundwaters. A possible source of cadmium in the deposit may have been from the oxidation of Cd-bearing sphalerite. The abundance of secondary V minerals (vanadinite, descloizite and mottramite) seen in the Devons Cut and Moxom Well deposits is quite rare for Australian mineral deposits. The V involved in the formation of these secondary vanadates may have been mobilised into groundwaters by the weathering of magnetite and pyroxenes in country-rock basalts. The interaction between V ions derived from the weathered mafics and Pb from the oxidation of hypogene galena allowed for the crystallisation of vanadinite, mottramite and descloizite, probably at low temperatures, under alkaline, oxidising conditions. U-Th-He dating of descloizite-mottramite from deposits such as Devons Cut has potential applications in the geochronology of the regolith^
ABSTRACTS alphabetically by surname of presenting author
Tropicana Deposit: a new gold province in Western Australia.
Tsunami hazard in Australia and steps being taken to mitigate it
Mark Doyle \ Bruce Kendall^ Gibbs\ Mark Kent^
Barry Drummond & Trevor Dhu
Duncan
^ AngloGold Ashanti Ltd, Level 13, St Martins Tower, 44 St Georges Tee, Perth, WA 6000 (mdoyle@anglogoldashanti. com. au) Tropicana is the first deposit discovered in a new gold province that straddles a tectonic suture between the Yilgarn Craton and the Proterozoic Albany-Fraser Province. The Tropicana JV partners AngloGold Ashanti Ltd (70%) and Independence Group NL (30%) have outlined an hdicated resource of 31.1 Mt @ 2.09 g/t Au and inferred resource of 31.7Mt @ 1.93g/t, totalling 62.8Mt @ 2.01 g/t for 4.05 Moz Au. The resource estimate is reported at a 0.6 g/t Au cut-off grade. The deposit comprises two grossly "stratiform" mineralised zones, the Tropicana zone to the north and Havana zone to the south. The deposit has been tested to a vertical depth of 350400m. Higher-grade extensions of the resource at depth may represent an underground mining target. Gneissic host rocks to the deposit can be grouped into six distinct facies associations, which are characterised by mineral assemblages that imply metamorphism at lower granulite facies. Mineralised zones are principally hosted within feldspar-rich divisions of the quartzo-feldspathic gneiss association and pegmatite facies association. Gold dominantly occurs as inclusions (10-30 |Lim) in pyrite (2-8%), <0.2mm) associated with closespaced anastomosing biotite-sericite fracture fills and crackle breccia zones that suggest a dominantly brittle deformation style during mineralisation. Gold mineralisation and associated strong biotite-sericite»calcite alteration is ascribed to a hydrothermal event that postdates the metamorphic thermal maximum. Evidence includes, but is not limited to: (1) mineralisation-associated alteration assemblages overprint high-grade metamorphic minerals and textures; (2) biotite-pyrite veins and fracture fills cross-cut and displace gneissic banding and transposed folds; and (3) mineralised veins and crackle breccia domains overprint pegmatite divisions that are interpreted as anatectic segregations formed during peak metamorphism. Mineralised zones are cut by mafic intrusions that are ascribed to the ca. 1210 Ma Fraser Dyke Swarm, providing a minimum age for mineralisation.
Geoscience Australia, GPO Box 378, Canberra ACT260L (Barry.Drummond@ga.gov.au; Trevor.Dhu@ga.gov. au) Most tsunami are caused by earthquakes that displace the water column by faulting the sea bottom or causing submarine landslides. Australia is surrounded by 8,000 km of active, earthquakeprone, plate margins. In Western Australia tsunami hazard is highest in the northwest facing the subduction zones of the Indonesian arc. Tsunami hazard along the eastern coast comes from subduction zones from the Solomon Islands in the northeast to the Puysegur Trench south of New Zealand. Images of the tsunami of 26 December 2004 impacting Thailand showed tsunami several metres high inundating large sections of shore line. Australia is much farther from the tsunami sources, and is more likely to face tsunami with smaller heights regionally but possibly increasing unpredictably to much larger heights locally. The Australian Government has funded the establishment of the Australian Tsunami Warning System (ATWS). End-to-end warning systems consider the development of mitigation strategies, monitoring for events, issuing warnings, and response and recovery phases after the event. The geosciences play important roles in several of these steps. Hazard mapping requires the study of the earthquake source regions (fault geometry, maximum likely earthquake magnitude and its probability, and estimates of the resulting tsunami height and direction). The development of mitigation strategies requires estimating the propagation of tsunami across the deep ocean, shoaling in the shallow waters near the shore line, the inundation of the land and the impact on people and infrastructure. The detection of earthquakes requires access to national and international seismograph networks that work interoperably in near-real-time, and algorithms for the rapid automatic determination of their locations (including depth), magnitudes and focal mechanisms. In cases where there are no sea level gauges between the source and coastline, the warning systems rely entirely on earthquake parameters. Published with the permission of the CEO of Geoscience Australia.
Australian Earth Sciences Convention 2008
85
86 ABSTRACTS alphabetically
by smmme of presenting author
Superimposed Neoarchean and Paleoproterozoic tectonometamorphic events in the Terre Adelie Craton (East Antarctica) Guillaume Duclaux\ Yann Rolland^, Gilles Ruffet^ Rene-Pierre Menot^ Stephane Guillot^ Jean-Jacques Peucat^ Mark Fanning^ Patrice Rey\ Arnaud Pecher^ ^CSIRO Exploration and Mining, PO Box 1130, Bentley, WA 6102, Australia (Guillaume.Duclaux@csiro.au) ^Geosciences Azur, CNRS, Universite de Nice Sophia Antipolis, Nice, France ^Geosciences Rennes, CNRS, Universite de Rennes 1, Rennes, France "^Magmas et Volcans, CNRS, Universite Jean Monnet, Saint Etienne, France ^Lahoratoire de Geodynamique des Chaines Alpines, CNRS, Universite Joseph Fourier, Grenoble , France ^Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia ^Earth Byte Group, School of Geosciences, The University of Sydney, Sydney, NSW, Australia Metamorphic petrology and geochronology are powerful tools for the understanding of the evolution of Precambrian composite basement. Several seasons of field investigations along the coastline of the Terre Adelie Craton (East Antarctica, ~136-145°E) - a part of the Mawson Continent allowed for the recognition of two majors age domains: (1) a Neoarchean basement, made of granulitic rocks on its eastern part overlain by amphibolitic rocks to the West, and (2) two Paleoproterozoic sedimentary basins overlying the Neoarchean amphibolitic crust and extending further West. The Neoarchean crust recorded a major granulitic event, followed by regional amphibolite facies retrogression, along with a large volume of monzogranodioritic melt intrusion during crustal thinning. New geochronological data from both domains of the Terre Adelie Craton reveal a tectonic evolution with three major peak activities. The main structural event occurred at ca. 2.45 Ga and is illustrated by Th-U-Pb electron probe analyses of monazites from the Neoarchean granulitic crust. This is in agreement with zircon ages known all over the Neoarchean domain. A local resetting at ca. 1.7 Ga in the Neoarchean domain is revealed by low temperature recrystallization of monazites related to fluid bearing anastomozed meter-scale shear zones. Furthermore, new "^^Ar/^^Ar ages obtained by stepwise heating techniques on amphibole, biotite and muscovite from both the Neoarchean basement and the Paleoproterozoic basins, illustrate the contrasting evolution of the basement and its sedimentary cover during the major 1.7 Ga compressive event. The Australian Earth Sciences Convention 2008
pervasive and severe tectonic and metamorphic imprint that characterized the Paleoproterozoic terrains is recorded in the Neoarchean basement only by weak and low temperature recrystallization which is restricted to localized shear zones. A final event at ca. 1.55-1.5 Ga is only recognized close to the Mertz Shear Zone (145°E) which limits the Terre Adelie Craton to the East. All these new data support a new detailed geodynamic history of the Terre Adelie Craton, from the Neoarchean to the Mesoproterozoic.
Tectonothermal evolution of the Kimban Orogeny, Southern Gawler Craton; evidence for extrusional tectonics during the development of a transpressional orogen Dutch. R.A.\ Hand, M.^ Kelsey, D.E. ^
^ Continental Evolution Research Group. Department of Geology and Geophysics. University of Adelaide, Adelaide, Australia, South Australia, 5005, Australia (email: rian. dutch@adelaide. edu. an) New geochronological, metamorphic and structural data provide new insights into the development of the regionally dextral, transpressional 1725-1690 Ma Kimban Orogenic system in the Southern Gawler Craton. EPMA monazite geochronology constrains the timing of metamorphism, deformation and the development of steep N-S to NE-SW fabrics to between 1725-1690 Ma. Mineral stretching lineations developed in the highest grade regions are near orogen parallel plunging generally gently to the north and south. Metamorphic analysis indicates that regions of the Southern Gawler Craton experienced granulite facies metamorphism at 700800 °C and up to 11 kbar followed by near isothermal decompression to approximately 5-6 kbar. Concomitant with this in adjacent areas metasedimentry packages only reached low-pressure andalusite grade conditions. These variations in metamorphic grade (associated with variations in crustal depths of up to 20 km) occur both along and across strike of the orogen with horizontal length scales of commonly less than 20 km. Integration of the geochronological, metamorphic and structural data sets indicates that rapid shallowly inclined extrusion of lower crustal material was juxtaposed against upper crustal material, producing a dome and saddle geometry, during the development of the strongly transpressional Kimban Orogeny.
ABSTRACTS alphabetically by surname of presenting author
Palaeoproterozoic hydrocarbons associated with uranium and gold deposits A. Dutkiewicz^. S.C. George^ DJ. Mossman^, H. Volk^ J.R. Ridley^, R. Buick^ ^School of Geosciences, University of Sydney, Sydney, NSW 2006 Australia, adriana@geosci. usyd. edu. au Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW 2109, A ustralia, sgeorge@els. mq. edu. au ^Department of Geography, Mount Allison University, Sackville, NB, Canada E4L A7, dmossman@mta. ca "^CSIRO Petroleum, P.O. Box 136, North Ryde, NSW 1670, Australia, Herbert. Volk@csiro.au Department of Geosciences, Colorado State University, Fort Collins, CO 80523-1482, USA, jridley@warnercnr. colostate. edu ^Dept. Earth and Space Sciences & Astrobiology Program, University of Washington, Seattle, WA 98195-1310, USA, buick@ess.washington.edu Organic substances have long been suspected of playing an important role in the formation of many world-class Precambrian mineral deposits. While most of this organic material has been severely altered, pris tine hydrocarbons are sometimes preserved inside fluid inclusions and can provide important clues to the hydrocarbon-ore fluid interactions. Our cases studies of the FA Formation from the Franceville Basin, Gabon, the Matinenda Formation from the Superior Craton, Canada, and the Vaal and Steyn Reefs from the Witwatersrand Basin, South Africa, demonstrate the presence of abundant oil-bearing fluid inclusions in sandstones and conglomerates associated with uranium and gold mineralization. In all cases, the oil occurs as a rim or an immiscible globule within complex liO and/or C02-rich inclusions trapped in intragranular and transgranular microfractures cutting detrital quartz. In the Franceville Basin, they also occur within syntaxial quartz overgrowths. Textural and microthermometric evidence in all these cases indicates multiple phases of oil migration and entrapment of oil, water and gas mixtures inside fluid inclusions. Oil migration occurred during burial digenesis of the host sequence, with oil migrating through primary intergranular pore spaces and into microfractures and cements formed during compaction. The presence of oil in inclusions in transgranular fractures indicates at least one episode of oil migration linked to deformation and/or epigenetic hydrothermal activity. Inclusion oils from the Matinenda Formation and from the FA Formation contain a typical suite of biomarkers, which are now considered commonplace in organic-rich Precambrian rocks.
These include isoprenoids, hopanes, 2amethylhopanes and steranes. The oils were likely sourced locally from horizons rich in organic matter derived from unicellular organisms within the host sequences during burial maturation and as a consequence of hydrothermal alteration. In the Franceville Basin, a phase of oil generation and migration is directly linked to the operation of natural nuclear fission reactors.
Sea level reconstructions from fossil coral reefs along the Cape Range coast, Western Australia Dutton. Stirling, C,\ Esat, T.^ Desmarchelier\ J., Lambeck, K. ^ ^ Research School of Earth Sciences, The Australian National University, Mills Rd., Canberra, ACT 0200, A ustralia (andrea. dutton@anu. edu. au, jol. desmarchel ier@anu. edu. au, hurt. lambeck@anu. edu. au) ^Department of Chemistry,University of Otago, P.O. Box 56, Dunedin, New Zealand (cstirling@chemistry. otago. ac. nz) Australian Nuclear Science and Technology Organisation (ANSTO), Institute for Environmental Research, B53, PMBl, Menai, NSW 2234, Australia (tze@ansto.gov.au) For the past two million years, the Earth's climate has oscillated between warm interglacials and cool ice ages with a periodicity of about 100,000 years. The present climate forms part of an interglacial regime, but during the last ice age about 21,000 years ago, temperatures were a few degrees cooler, ice sheets were considerably larger, and sealevels were about 130 m lower than at present. Superimposed on these glacial-interglacial changes are abrupt climate reorganizations that occur on millennial to decadal timescales. Understanding the mechanisms underlying these abrupt climate shifts is essential to address emerging societal concern about the magnitude and rate of future climate change in the presence of global warming. Western Australia's fossil coral reefs contain a wealth of information on processes driving Earth's natural climate cycles. Coral reefs are important archives of past climate change because they grow close to the sea-surface, providing valuable information on both sea level and temperature fluctuations, especially during warm interglacial periods when reefs grow prolifically. Previous work carried out on fossil coral reefs that line the WA coast identified the timing and magnitude of last interglacial highstand (Stirling et al., 1995, EPSL, V.135, p. 115; Stirling et al., 1998, EPSL, v. 160, p.745). We have set out to extend the scope of this previous work and date additional samples from various locations in the Cape Range National Park using U-series techniques to better characterize the continued next page... Australian Earth Sciences Convention 2008
87
88
ABSTRACTS alphabetically by surname of presenting author
timing of sea level oscillations associated with the last interglacial. We will highlight resuUs from samples collected during the 2007 field season and implications for constraining past sea level fluctuations.
Investigating Petroleum Systems Using Micron-scale Tracers within Sedimentary Grains. Peter Eadington^^ Richard Kempton\ Herbert Volk\ Keyu.Liu^ Andrew Ross^ ^CSIRO Petroleum Resources, ^Peter. Eadington@csiro. au Fluid inclusions in sedimentary grains reveal the oil migration and fill history of petroleum reservoirs which provides insights into petroleumsystems. Petroleum systems analysis is a framework to evaluate the natural systems, in which oil was generated, migrated, accumulated and was preserved; all elements being necessary to have oil accumulations. It relates the sedimentary basin fill to fluids that migrated in response to buoyant interactions and earth movements. Fluid inclusions, sealed chambers formed by crystallization of minerals, preserve oil, gas, or formation water within them over millions of years. They may occur in different parts of grains that represent a superposition sequence and indicate the nature of the pore fluid when the inclusions were formed. Fluid inclusions are used in geochemical, structural and palaeo-hydrologic investigations to identify the source rock, to evaluate fault seal, and to inform determination of water saturation in petroleum reservoirs, and many other applications. In some reservoirs without preservation inclusion oil may be the only oil available for geochemical analysis of biomarkers to determine the character of the source rock and to correlate with oil elsewhere in the basin. It has identified new petroleum systems. Mapping the abundance of oil inclusions in depth profiles or maps indicates palaeo-oil zones that may be a proximity indicator. If oil moved by buoyant displacement it may now reside below the gas. Fauh seal analysis contrasts structural features of traps in oil-producing reservoirs with those in reservoirs that did not preserve palaeo-oil, to rank and prioritise prospects for management of risk. Microthermometric measurements of the salinity and resistivity of formation water in oilwater and aqueous inclusions indicate a time series of changing composition, identifies transients of exotic water in formations, and informs the selection of resistivity of irreducible water as a key input to determining water saturation in petroleum reservoirs.
Molecular & Isotope Chronostratography of Tertiary source rocks and crude oils Christiane Eiserbeck^ Kliti Grice\ Joseph Curiale^ ^ Curtin University of Technology, Perth, Australia (c. eiserbeck@exchange. curtin. edu. au) (K. Grice@curtin. edu. au) ^ Energy Technology Company, Sugar Land, Texas, USA One of the most interesting and dramatic events in geological history is the Paleocene-Eocene thermal maximum (PETM) spanning the PaleoceneEocene boundary, 55 Ma ago. The PETM was characterized by a sudden global warming thought to be caused by a massive input of atmospheric greenhouse gases (Sluijs et al., 2006, Nature, v. 441, p. 610). This led to mass extinction of both marine and terrestrial life and evolution of new species. For example, the global warming caused increased growth of high-latitude forests and the explosion of the angiosperms. The entire ocean warmed and the sea surface temperature rose 5-8°C (Zachos et al., 2003, Science, v. 302, p. 1551). There is a prominent negative carbon isotope excursion (CIE) of both organic and inorganic carbon in terrestrial and marine sediments across the PETM boundary which signifies an input of huge amounts of ^^C-depleted carbon dioxide. The negative CIE has a range of 2.5%o in marine bulk carbonate to -6%o in higher plant ^-alkanes (Pagani et al., 2006, Nature, v. 442, p. 671). In the Arctic Ocean, the sea surface temperature rose to 2 3 a n d was of lower salinity, almost freshwater-like. Therefore, the Azolla fern grew and reproduced in Arctic Ocean surface waters in large quantities (Brinkhuis et al., 2006, Nature, v. 441, p. 606). Samples from the PETM and early Eocene in parts of the Arctic region are characterized by an above-average total organic content (TOC) of 5% and in some instances have a high source rock potential. Preliminary investigations are underway using a compound specific isotope biomarker approach, particularly focusing on higher plant derived compounds. Samples include source rocks and crude oils from Tertiary deltaic basins from Alaska and Canada.
Ichnology of the Upper Cretaceous (Cenomanian - Campanian) Sequence of Western Sinai, Egypt: Taxonomic, Paleoecological Implications Magdy M. El-Hedeny^ ^Geology Department, Faculty of Science, Alexandria University, Moharram Bay 21511, Alexandria, Egypt, (m_elhedeny@yahoo.com)
Australian Earth Scien
ABSTRACTS alphabetically by surname of presenting author
The Upper Cretaceous (Cenomanian Campanian) sequence of western Sinai, Egypt contains relatively abundant and moderately diverse ichnotaxa that are described herein. The recorded ichnofauna represents domichnial, praedichnial and fixichnial structures. The sequence includes Caulostrepsis spiralis Pickerill et al., 2001; C. cretacea (Voigt, 1971); Entobia ovula Bromley and D'Alessandro, 1984; E. cretacea Portlock, 1843; E. isp., Gastrochaenolites cf. torpedo Kelly and Bromley, 1984; Gastrochaenolites isp., Talpina ramosa von Hagenow, 1840; Maeandropolydora decipiens Voigt, 1965; M. sulcans Voigt, 1965; M. cf. elegans Bromley and D'Alessandro, 1983; Oichnus paraboloides Bromley, 1981; O. excavatus Donovan and Jagt, 2002; Rogerella pattei SaintSeine, 1954; Trypanites weisei Magdefrau, 1932 and Renichnus arcuatus Mayoral, 1987. Nearly all these ichnotaxa are formally documented for the first time in Egypt. C. spiralis found in the Upper Cenomanian, represents the oldest record of this ichnotaxon. In addition, the occurrence of Renichnus arcuatus in the Upper Cretaceous (Middle Coniacian) of Egypt could extend the stratigraphic range of this ichnotaxon from the Maastrichtian, down to the Middle Coniacian, and expands its known geographic distribution, during this period, from southern and central Europe (Spain, Greece and Netherlands) to North Africa (Egypt). Paleoecologically, the studied ichnofossils characterize the shallower marine biofacies in the Cenomanian - Campanian of Sinai and reflect the principal shallowing events during this period in that region.
Towards a better assessment of the Seismic hazard in the southwest of Western Australia Beatriz Estrada^ Mike Dentith\ Dan Clark^ Karl-Heinz Wyrwoll ^ School of Earth and Geographical Sciences The University of Western Australia Natural Hazard Impact Project Geospatial and Earth Monitoring Division Geoscience Australia Despite being classified as a stable continental region, the southwest of Western Australia is one of the most seismically active areas in the Australian continent. Most of the current seismic activity in this region occurs in the Southwest Seismic Zone (SWSZ), which has been considered as representing the highest seismic hazard in the region. In recent years, numerous scarps, potentially related to significant pre-historical earthquakes (palaeoearthquakes) have been recognized not only within the SWSZ but also across a wider region within the southwest of Australia. This suggests that
the earthquake activity is not only confined to the SWSZ but that there is a potential for earthquakes to occur in other parts of the southwest of Western Australia that have not been previously considered in the assessment of the seismic hazard of the region. Palaeoseismological investigation at two of these fault scarps, the Dumbleyung and the Lort River scarps not only confirmed their association with surface rupturing palaeo-earthquakes but also indicated events with likely magnitudes of ~Mw 6.87.0. Two trenches excavated across the Dumbleyung Fault scarp, indicate that three earthquakes have been associated with this scarp in the last ca 24-60 ka, with a possible Holocene age for the last recorded earthquake event. Another two trenches excavated across the Lort River Scarp, indicate two events in the last ca 35 ka with a likely late Pleistocene age for the last event recorded in the trenches. Assessments of earthquakes scenarios (seismic hazard) based on these events (Mw 7.0) indicate peak ground accelerations up to 2g in the near-fault fields. These events would significantly affect towns such as Wagin, Dumbleyung, Katanning Narrogin and Yealering, close to the Dumbleyung Fault, and the town of Esperance, close to the Lort River Fault. These events are not likely to cause damage in Perth.
The Psychology of Decision-Making in Mineral Exploration - A Key to Improving Return on Investment in our Business Mike Etheridge^ Colin Wastelf, Gillian Lucas^ Lisa Hartley^, Maureen McMahon^ ^GEMOC Key Centre, Department of Earth and Planetary Sciences Department of Psychology ^Macquarie Graduate School of Management Macquarie University NSW2109 (Current Address for author: 25 Darvall St, Balmain, NSW 2041) E-mail: mike. etheridge@tectonex. com. au The business of mineral exploration is largely ±)out making the best possible investment decisions across a portfolio of opportunities with highly uncertain future values. The business should certainly be founded on quality geoscience, but better science does not necessarily guarantee a better financial outcome. However, consistently making the best investment (and disinvestment) decisions will have a marked impact on the financial return. So can we learn to make better investment decisions in the face of the substantial risk and uncertainty that bedevil our business? There is a fertile body of knowledge on decisionmaking under uncertainty, much of which is applicable to mineral exploration, and which has been widely applied to other areas of business. This talk begins with
continued next page..
Australian Earth Sciences Convention 2008
89
90 ABSTRACTS
alpliabeticallyfofsurname of prasenting auttior a few highlights from this body of knowledge that are particularly lelevant to mineral exploration. However, most of the talk will present the outcomes of an on-line survey of decision-making styles carried out with about 100 mineral exploration practitioners. The survey was distributed on-line to exploration professionals in the nine mining and exploration companies that were sponsors of an industry collaborative research project at Macquarie University entitled 'Improving Mineral Exploration Performance by Superior Management of Risk, Uncertainty and Value". Participation was voluntary and confidential. The survey comprised two main parts: 1) a set of standard psychometric tests designed to assess the individual's decision-making style and attitude to risk, and 2) three exploration scenarios involving decisions as to exploration risk, value and progress. The survey respondents covered a wide range of ages, years of experience, seniority and company sizes, and the cohort is considered to be a reasonable proxy for the industry as a whole. The principal outcomes of the survey are as follows. 1. Probabilities of discovery assigned by participants in individual exploration scenarios ranged over more than two orders of magnitude, irrespective of the quantity / quality of the exploration information provided, suggesting that many exploration professionals have no sound basis for assessing exploration risk. 2. The mean probability of success in each scenario from the group was arguably significantly higher than the known industry average success rates and the information provided would support. This suggests that the respondent group is overoptimistic and/or lacks sufficient understanding of industry base rates of discovery. 3. There was a good correlation between the psychometric measures of rationality and the assignment of lower probabilities of success, especially in the exploration scenario that tested knowledge of base rates of success. Given the information in this scenario, probabilities of success at the lower end of the range are more likely. This suggests that people with more rational behavioural characteristics may make consistently better decisions than those with more intuitive or optimistic characteristics. 4. In one of the scenarios, the respondents were asked how much they would recommend their company should pay in cash for a tenement package, having already assigned probability of success for discovery of a mineable porphyry deposit. Given the assigned probability of success and the likely value range of a mineable porphyry cfeposit, the proposed cash payments significantly undervalued the opportunity. This is consistent with widely tested human behavior, which values a loss more highly than a gain of the same amount, but it also reflects a built-in risk aversion affecting investment decisions in our business. Australian Earth Sciences Convention 2008
5. When faced with exploration failure following an initial success, respondents showed a significant bias to continue exploring other prospects despite having limited funds. Among those who continued drilling longest, there was a moderate correlation with a psychometric measure of the "need for closure". The key finding from this research is that behavioural and cognitive biases that have been established by decades of psychological research are likely to significantly influence decision making in mineral exploration. Just because we are scientists, we are no more likely than other humans to be rational. Indeed, the high level of scientific uncertainty in geosciences may make us more prone than other professions to exhibit these biases. The virtual absence of training in the basics of probability theory among geoscientists certainly does not help us to assess potential bias and make better decisions. There is also some indication that the personal attributes and behaviours commonly valued among exploration professionals, such as optimism, intuition, gut-feel and persistence, may contribute to poor investment decisions. This is likely to be particularly true for the key decision to terminate a project. In conclusion, there is significant leverage in better understanding of human behavioural and cognitive characteristics to improve mineral exploration decision making and return on investment. This has important implications for the education and even selection of senior exploration professionals who make such decisions, and for the nature of the decision-making process.
The extent and distribution of the Kalkarindji Large Igneous Province.
Lena Z. Evins\ David Phillips^, Fred Jourdan? ^ School of Earth and Geographical Sciences, The University of Western Australia,35 Stirling Highway Crawley WA 6009 (levins@cyllene.uwa.edu.au) ^ School of Earth Sciences, University of Melbourne, Victoria 3010 (dphillip@unimelb.edu.au) ^ Western Australian Argon isotope facility Department of Applied Geology & JdL Center Curtin university of Technology, WA 6845 (fjourdan@curtin.edu.au) Establishing the extent of a Large Igneous Province (LIP) can be a complicated task even for relatively young provinces. Here, we discuss the extent of the oldest Phanerozoic LIP: the Early Cambrian Kalkarindji LIP in northern and central Australia, coeval with the Early-Middle Cambrian mass extinction. Today, the remnants of this vast province is found in an area of at least 750 000 km^, stretching from westernmost Queensland to the Kimberleys, Western Australia. However, burial,
ABSTRACTS aiphabeticaify by surname of presenting author
erosion and the effects of plate tectonics are adding complexity to the task of estimating the original extent of this LIP. New geochemical and ^^Ar/^^Ar geochronological results presented here show that the Table Hill Volcanics and intrusives in the Officer basin in the southwestern and central parts of Australia form a part of the province. With these rocks included, the extent of the province is estimated to have covered 2.1 million km^. In one part of the province, different members have been defined: two major members are the glomeroporphyritic Bingy Bingy basalt member, and the Blackfella Rockhole member, mainly consisting of volcanic breccia. The extent, thickness and significance of these two members are discussed here. Rocks likely to be a part of the Kalkarindji LIP occur also in the Harts Range, Northern Territory. There are dikes of similar age in the Kanmantoo sedimentary rocks gA), and in southern Western Australia; both of these locations have been suggested as possible parts of this province. Remnants may also be f)und on other continents; the Tarim block of western China was rifted from Australia at the time of the Kalkarindji LIP formation, and the dikes of SW Australia have counterparts in Antarctica. We speculate also on the role of the Lasseter Shear zone, a cmstal-scale transcurrent feature, in the distribution of the Kalkarindji LIP.
Little time for a lot of LIP: Relative timing of magmatism and deformation during the c. 1070 Ma Giles Event in the Musgrave Complex of Western Australia
Paul M . E v i n s \ H u g h Smithies^ Heather Howard^ ' Geological Survey of Western Australia, Mineral House, 100 Plain Street, East Perth, WA, 6004 (paul. evins@doir. wa.gov. au) Ongoing detailed mapping of the western Musgrave Complex has revealed that the Giles Event is a complex sequence of at least 5 mafic and 5 felsic magmatic events coupled with intense deformation that occurred over a short time span. Magmatism began with deposition of the Mummawarrawarra Basalt. This was followed by emplacement of the large (up to 2500 kn^ and 10 km thick) layered mafic and ultramafic Giles intrusions that collectively form one of the largest layered mafic suites in the world. Subsequent intrusions of similarly voluminous un-layered gabbro cut the layered suite. Emplacement of the un-layered mafic suite was accompanied by felsic magmatism and deformation. The felsic magmas are preserved as stringers and xenolithic blebs, where mafic and felsic magmas mingled in syn-magmatic shear zones. During the waning stages of deformation, felsic magmas were
again introduced as rapakivi granite at deeper levels, acicular hornblende granite at higher levels and the trachydacitic Smoke Hill Volcanics and Hogarth Formations at the surface. Concurrent uplift exposed some of the layered intrusions as basement on which the Smoke Hill Volcanics were extruded. The uplift may have been accommodated along amphibolite facies shear zones. These shear zones are cut by plagioclasephyric gabbro dykes. The Saturn mafic ring complex and Tollu granite pluton represent two distinct intrusive bodies that crosscut all of the previous events. The final magmatic event is manifested as rare, NW trending aplites, granites, and pegmatites. These were commonly focused along the centre of the plagioclase-phyric gabbro dykes. Isotopic ages from one of the earliest felsic magmatic events and from the Tollu granite pluton constrain most of the above magmatism and deformation to within a 2 a error band of 10 Ma, with the actual time frame likely much less.
Textural Controls on c. 1675, 1600, and 510 Ma M onazite Around Broken Hill Paul M . Evins^ - l William J. Collins^ Roberto Weinberg ^ Geological Survey of Western Australia, Mineral House, 100 Plain Street, East Perth, WA, 6004 (paul evins@doir. wa.gov. au) School of Earth and Environmental Sciences, James Cook University, Townsville, QLD, 4811 School of Geosciences, Monash University, Clayton, VIC 3800 In situ EPMA monazite dating has been used to constrain fabric ages around Broken Hill. Two Sundown Group pelites contain abundant ~ 1675 Ma monazites preserved as Si-parallel (regional, shallowdipping S2) porphyroblast inclusions. Matrix monazite ages in these samples show age peaks at ~ 1675, ~ 1635, and ~ 1600 Ma. A pelite 25m away from one of the above samples and two samples from the Sundown syncline, all with a strong steep S3 foliation, yield mainly -1600 Ma monazite ages. The difference in monazite ages from the two adjacent samples indicates deformation partitioning played a role in -1600 Ma monazite growth. Ages from these 5 samples suggest that D3 occurred at 1600 Ma, but peak granulite facies metamorphism associated with S2 must be older. Peak metamorphism occurred either - 1675 Ma or ~ 1635 Ma. If it was - 1635 Ma, then the - 1675 Ma peak is a detrital population. A lower grade pelite from a similar stratigraphic level as the above samples yielded monazite ages ranging from >1700 Ma to - 1550 Ma with a main peak at ~ 1600 Ma represented by monazites parallel to S3. The lack of a 1675 Ma age peak suggests this age is not detrital, and ~ 1675 Ma peak metamorphism was localised.
continued next page...
Australian Earth Sciences Convention 2008
91
92 ABSTRACTS alphabeticaUy by sorname of presenting author
A leucogneiss from near the Stephens Creek shear zone is overprinted by a weak, spaced, retrograde S4 cleavage. Apart from one 1607 Ma grain, all monazites were reset to - 5 1 0 Ma, indicating such major shear zones are probably of Delamarian age. Some counterintuitive textural controls on monazite growth are evident. During metamorphism and deformation, rigid porphyroblasts (e.g. garnet) may fracture becoming less successful at armouring monazite than grains that deform by recrystallization, recovery, or creep (eg. quartz, feldspar, cordierite, etc.). The oldest age population is best represented by < 20 mm grains or intragrain domains, which may reflect sampling bias in previous studies limited by analytical spot size.
Geology of the submarine Mellish Rise off Northeast Australia N.F.Exon\ G.Bernardel^ K.L.Hoffmann^ P.G.Quilty\ C.S.Findlay^ & J.Brown^ ^ Department of Earth and Marine Sciences, Australian National University, Canberra 02000. (Neville.Exon@anu.edu.au) ^Geoscience Australia, PO Box 378, Canberra 2601 (George Bernardel@ga.gov.au) ^ Geological Sun^ey of Queensland, 80 Meiers Rd, Indooroopilly, Queensland 4068. (Kinta. Hoffmann @ dnie. qkl mv. au) ^ School of Earth Sciences, University of Tasmania, Private Bag 79, Hobart 7001 (P.Quilty@utas.edu.au) ^ (Claire.Findlay@dest.gov.au) ^ Geological Survey of Canada, 601 Booth St. Ottawa, ON KIA 0E8 (juliebrown233@gmail.com) The submarine Mellish Rise, mostly 2000-3000 m deep, lies - 5 0 0 km northeast of Queensland. It trends northeast and is 700 km long by up to 300 km wide. The Coral Sea Basin and Louisiade Trough to the northwest, and the South Rennell Trough and west D'Entrecasteaux Basin to the southeast, are deeper than 3500 m and are probably underlain by oceanic crust. Mellish Rise and the adjacent Louisiade Plateau lie deeper than nearby continental plateaus, suggesting thin, highly extended continental crust. A Geoscience Australia survey of Mellish Rise by R.V. Southern Surveyor (SS02/2005) involved multichannel seismic profiling, multibeam bathymetry, and seafloor sampling. Twenty-three successful dredge sites recovered volcanics, sediments and sedimentary rocks, and minor metamorphics. Foraminiferal, calcareous nannofossil and petrological studies were carried out on rocks and sediments. Rifting of pre-existing basement rocks, Mesozoic sediments and rift volcanics in the Late Cretaceous and Paleogene, related to seafloor spreading, formed northeast-trending rift basins bounded by major plateaus and escarpments. Australian Earth Sciences Convention 2008
Dredging of plateau escarpments yielded basalt, dolerite and other rift volcanics, probably Early Cretaceous in age. Continental basement is suggested by dolerite; quartz-rich fragments in volcanic conglomerates; and quartz, mica and metamorphic grains in Cenozoic carbonates and siliciclastic sediments. Hyaloclastites dominate the (locally) Eocene hotspot volcanoes of the Tasmantid seamount chain. The rift basins contain over 2500 m of Upper Cretaceous and Cainozoic sedimentary rocks and sediments in four distinct seismic sequences. Both shallow and deep marine carbonates were commonly dredged: largely Late Paleocene, late Middle to Late Miocene, or younger. The ages of the (frequently reefal) shallow marine carbonates correspond with known periods of reef growth in the Great Barrier Reef. DSDP and ODP drill sites in deep water in the general region contain siliceous chalks in the latest Cretaceous to Middle Eocene and pure chalks thereafter - and our samples fit this picture. The drill sites document regional unconformities (Paleocene-Eocene and EoceneOligocene boundaries). Eocene-Oligocene bentonitic claystone, and widespread fine grained 'redbeds' (lateritised volcanics), could represent Eocene hotspot volcanism. Siliceous sinter suggests the presence of hydrothermal springs on dry land - probably in the Eocene or earlier.
Coring the Cenozoic sequences of the northern Carnarvon Basin of Australia to answer global eustatic questions Neville Exon\ Carla Sanchez^'^ Craig Fulthorpe\ James A. Austin^ Jr. ^ Department of Earth and Marine Sciences, Australian National University, Canberra 0200. (Neville.Exon(^anu.edu.au) ^ The University of Texas at Austin, Department of Geological Sciences. PO Box B, University Station, Austin, TX 78713-8902 (Carla@ig.utexas.edu) ^ University of Texas Institute for Geophysics. J.J. Pickle Research Campus, Bldg. 196, 10100 Burnet Road(R2200), Austin, Texas 78758-4445 (Craig(@utig. ig. utexas.edu; Jamie@utig. ig.utexas.edu) Prograded Cenozoic sequences of the northern Carnarvon Basin are the subject of a highly ranked Integrated Ocean Drilling Program (lODP) proposal (Proposal 667), designed to understand timing and amplitudes of global sea level (eustatic) changes and stratigraphic responses. This would complement an ODP/IODP program that involves the prograded Cenozoic sequences of the New Jersey margin and the Canterbury Basin (NZ). The proposed continuous coring would be in several holes each >1000 m deep. The prograding sequences are known through studies of petroleum exploration wells and 3-D seismic sequences, but these sequences were never themselves
ABSTRACTS alphabetically by surname of presenting author
the main focus of exploration company studies. The University of Texas at Austin has taken the lead in the study of the sequences with a view to obtaining continuous lODP cores, which would allow 1) calibration of the sequence stratigraphy with detailed age control, and also provide paleobathymetric estimates; 2) reconstruction of original depositional geometries and estimation of eustatic amplitudes using flexural backstripping; 3) investigation of the stratigraphic response to sea-level changes. The three broad sequences of interest are Middle Miocene cool-water carbonates (Trealla Formation); late Middle Miocene to Late Miocene siliciclastic sediments (Bare Formation); and Late Miocene to Recent warm-water carbonates (Delambre Formation). The Trealla Formation prograded northwest, and consists largely of skeletal grainstone nearshore and pelagic marl offshore. The Bare Formation prograded northeast (beneath the present inner to middle shelf) and consists largely of mature quartz sandstone. The Delambre Formation prograded northwest (beneath the present outer shelf) and grades upward from calcisiltite to calcilutite. The Bare Formation is presently the subject of a detailed study. It formed a deltaic system, deposited as quartz-rich sands on a predominantly carbonate margin, during a long-term sea-level fall and global cooling. Shallow-water carbonate platforms subsequently developed on local highs on siliciclastic barrier spits and/or delta lobes. 40.Ar/^^Ar dating and noble gas and halogen
constraints on orogenic gold mineralisation in Victoria, Australia.
Alison Fairmaid^ David Phillips^ Mark Kendrick^ and Bin Fu\ ^ School of Earth Sciences, The University of Melbourne, Victoria, Australia. (a.fairmaid2@pgrad. unimelh. edu. au) The Ballarat East (408/) and Maldon gold deposits (56/) in the (c. 0.4 Ga) western Lachlan Fold Belt of Victoria, Australia, are being investigated. Ballarat East is a typical 'orogenic' gold deposit, whereas the Maldon deposit, located in contact aureole of the Harcourt granite, represents either reworked orogenic gold or an intrusion-related deposit. The existing "^^Ar/^^Ar geochronological database for Victoria is extensive. However, further work is warranted to clarify the relationship between these ages and gold deposition. For example, tie wide range of ages (455-370 Ma) for Ballarat East could reflect multiple deformation events and/or detrital ages, and some of these ages may be unrelated to gold mineralisation. The youngest mica ages of -370 Ma, determined for the Maldon deposit, could have been reset by intrusion of the nearby Harcourt Granite. The Ballarat East and Maldon deposits provide excellent opportunities to simultaneously refme constraints on the timing of hydrothermal alteration in
Victoria, and reveal the source of hydrothermal fluids. Gold-bearing quartz veins contain CO2-H2O fluid inclusions and have either muscovite selvages or contain albite/muscovite, which are excellent targets for '^Ar/^'Ar dating. The fluid inclusion noble gas isotopic (Ar, Kr and Xe) and the halogen (CI, Br and I) compositions can be determined simultaneously by noble-gas mass spectrometry of irradiated samples (extended Ar-Ar methodology). Used in conjunction with neon isotopes measured in non-irradiated samples, Ne, Ar and Br/ClI/Cl are powerful tools for determining the origin and interaction of fluids. Both groups of elements behave conservatively in much of the Earth's crust. Halogens can unravel processes such as the acquisition of salinity, whilst noble gas isotope ratios vary by orders of magnitude, making minor contributions from different fluid reservoirs or fluid mixing easy to identify. We will present data to test two contrasting hypotheses. The conventional view is that the fluids are of metamorphic origin. An alternative model developed in the Yilgarn (Kendrick et al, this volume) emphasises a role for mantle-derived volatiles.
Age constraints on the Sturtian Glaciation in Adelaide Geoscyncline, South Australia and the Pocatelo Formation of Idaho, USA indicate that there was no single Sturtian Snowball. C. Mark Fanning^ and Paul Karl Link^ ^ Research School of Earth Sciences, The Australian National University, ACT 0200 (Mark.Fanning@anu.edu.au) ^ Department of Geosciences, Idaho State University, Pocatello, ID 83209-8072, USA (linkpaul@isu.edu) The concept of a single, presumed synchronous, "Sturtian glaciation" has been interpreted or used uncritically in many Snowball earth discussions dealing with Neoproterozoic paleoclimatology and tectonics. This single Sturtian glaciation has been thought to be as old as 770 to 750 Ma with suggestions that 720 Ma is the age of the Sturtian glacial deposits in South Australia; the latter is not based on hard geochronologic data (i.e U-Pb zircon age determination). In fact, reliable ages on world wide correlated Sturtian glacial rocks are sparse, and often misquoted. In southeastern Idaho the Sturtian glacial portion of the Pocatello Formation is seen to be younger than 700 Ma (volcanic clast within diamictite) and older than 667 ± 5 Ma (tuffaceous layer above cap carbonate). Elsewhere in Idaho, a stratigraphically less well constrained fels ic volcanic is now dated at 686 ± 4 Ma. West of Copley in northern South Australia, a tuffaceous bed in the lower Wilyerpa Formation, Yudnamutana Subgroup, Umberatana Group has a dominant igneous age component at ca. 659 Ma. This tuffaceous horizon is within the Wilyerpa Formation that comprises heterogeneous bedded diamictite,
continued next page...
Australian Earth Sciences Convention 2008
93
94
ABSTRACTS alphabetically by surname of presenting author sandstone and siltstone containing ice-rafted debris, across the central and northern Flinders Ranges. At Copley, dropstones are abundant in the Wilyerpa Formation above and below the tuff bed. This 659 Ma age constraint on the Sturtian glaciation is consistent with Re-Os ages on post-Sturtian glacial black shales from Tindelpina Member of Tapley Hill Formation South Australia (643 ± 2.4 Ma; Kendall et al. 2006, Geology v. 34, p. 729) and Aralka Formation, Central Australia (657.2 ± 5 . 4 Ma). It is a reasonable conclusion that the Sturtian glaciation is diachronous on a global scale, and that there were likely several phases within Sturtian glaciation, precluding the possibility of a single Sturtian Snowball event.
Towards laboratory study of dislocationrelated seismic-wave attenuation in olivine Robert Farla\ Harri Kokkonen\ John Fitz Gerald^ Auke Bamhoom^'^, Ulrich FauP and Ian Jackson^ ^ Research School of Earth Sciences, Australian National University, Canberra, ACT0200, Australia. ^ Now at Department of Earth Sciences, Utrecht University, 3508 TA Utrecht, The Netherlands ^ Department of Earth Sciences, Boston University, Boston, MA 02215 USA Dislocations introduced into mantle minerals like olivine by prior/ongoing tectonic deformation may account for a significant fraction of the observed seismic wave attenuation. In preparation for laboratory measurements of such dislocation damping, we have undertaken a study of high-temperature dislocation recovery in polycrystalline olivine. Here we extend previous work on natural olivine to a new class of pure synthetic F090 material, prepared from a sol-gel precursor and pre-deformed dry at 1300°C and progressively greater levels of deviatoric stress, reaching 255 MPa, to a total stain of almost 20%. Multiple small cores of the pre-deformed specimen were subjected to static annealing for periods of 3-50 h at temperatures of 1100-1450°C under controlled furnace atmosphere within the olivine stability field. Dislocations were revealed via an oxidation-decoration technique and imaged using backscattered electrons (BSE) in a Hitachi 4300SE FESEM operated at 5kV. For each annealed sample, dislocation densities were measured across a minimum of two regions totalling 5000 area to reduce uncertainties. The free software package ImageJ was used to threshold and highlight the dislocations which were then automatically counted. A manual correction for their 3D orientations was applied to obtain a reliable dislocation density. The difference between the initial and the final dislocation density follows a second-order kinetic rate law as a function of annealing time, and results suggest an activation energy of dislocation mobility of - 2 8 0 Austraiian Earth Sciences Convention 2008
kJ/mol. It follows that dislocation microstructures developed during prior deformation can be preserved during subsequent measurements of seismic properties at temperatures as high as 1100°C. Comparative results from preliminary forced-oscillation measurements of dislocation damping in undeformed and pre-deformed olivine specimens will be presented.
Volume change behaviour of unsaturated compacted clay under plane strain condition Miftahul Fauziah^, Hamid Nikra^ ' Research student at Curtin University of Technology, Western Australia, also lecturer at Indonesian Islamic University, Yogyakarta, Indonesia, (miftahul.fauziah@curtin. edu. au) ^ Associate Professor Curtin University of Technology, Perth, Western Australia, (Nikraz@vesta.curtin. edu. au) Estimation of volume changes in compacted soils is an important aspect for the analysis, design and performance of geotechnical works. It has been observed that several stability problems, involving those materials, are due to water content changes and therefore to matric suction changes that occur periodically in nature. Although soils are generally assumed fully saturated below the groundwater table, they may be semi saturated near the state of full saturation under certain conditions. The situation of partial saturation m a y b e caused by several factors, such as variation of water table level due to natural or manmade processes. The behaviour of unsaturated soil are quite different from those of saturated soil because of the influence of suction. Results obtained with the strength theory of saturated soil could not be directly applied to solve the problems related to the unsaturated soil. It has been known in geotechnical engineering that the partial saturation of soil usually gives higher strength and lower compressibility This study was undertaken to delineate the effects of soil water suction history on volume change behaviour of compacted kaolin clay under plane strain condition. The biaxial apparatus, which was used in this study, is a modification of the conventional triaxial apparatus. Cell pressure from the triaxial compression test and a rigid loading platen are used to apply the minor (03) and major (ai) principle stresses, respectively, to the clay specimen. The specimen is mounted inside the device, which fully restrains any out-of-plane deformation by the use of a pair of rigid perspex wall. The volume change of the sample was measured by local strain devices while the water volume change was recorded by a volume gauge. Results from the tests were compared with the theoretical analysis within the elasto-plastic critical state model for unsaturated soil.
ABSTRACTS alphabetically by surname of presenting author
Joining Forces for (geoscience) Knowledge - Groundwater & Mineral Exploration, Same Approach, Different Targets Jon Fawcett^ Don Cherry^ Mark Reid^ ^ Department of Primary Industries, Future Farming Systems Research Division, Bendigo, Australia) In Victoria, there is a new mineral search emphasis on bedrock-hosted ore bodies underneath Tertiary formations that include the Newer Volcanics basalts, the Calivil Formation (Deep Lead) and other Murray Basin sediments. Some of the new areas of mineral interest coincide with areas of significant groundwater interest, including prescribed Groundwater Management Areas (GMAs) or Water Supply Protection Areas (WSPAs). There has also been in recent years an increasing use of groundwater chemistry in exploration geology to define potential mineral targets. Newly drilled bores, existing bores and windmills have been sampled for analysis. Unfortunately, an absence of rigour in the sampling procedure has compromised the quality of groundwater chemistry in many cases. It is also noted that hydrogeological and landscape system studies have tended not to utilise all available geological data when developing conceptual models. For example, mineral exploration drill hole data have been often overlooked. Groundwater flow models are commonly over-simphfied, often only using 2 or 3 layers and poor or invalidated assumptions regarding hydraulic connection and boundaries. It is interesting that both the hydrogeological and mineral exploration professions have access to a lot of the same resources but generally carry out studies in isolation. Whilst there exists some sharing of knowledge through published reports and government and private institution databases, this generally occurs after the exploration program or groundwater investigation has concluded. Greater communication and integration of exploration and hydrogeological programs is suggested to improve the knowledge building capacity of field based studies. Improvement in the quality of current geological and hydrogeological data bases and a framework that captures new data outputs such as GIS layers, hydrochemical data sets and interpreted geophysical data sets are required to enable more effective geological studies and better understanding of mineral and groundwater occurrence..
Information Technology & Geoscience: Introducing Technology Parks & Incubators of Geoscience Mr Ardalan Fazel Valipour^ Mr Mahdi Vahab Zadeh^ 'Department of Geology, Faculty of Sciences Islamic azad universitymashhad branch, Iran, (drajv @yahoo. com) Parks and incubators of the kinds of trade, technology, invention and science and technology parks are the ways to over come difficulties facing different sections. Regarding the need of mankind to geoscience, lack of fast applicability of the available theories in this field, the numerous number of the graduates in this field seeking job, and also in accordance of their knowledge and industry needs, geoscience incubators or parks can be suitable and intermediate environments between geoscience educational institutions and industry. The aim of this paper is to introduce geoscience technology parks and incubators in the world and their impacts in this field.
New mapping from potential fields data in the Air, Damagaram, and South Maradi regions of Niger, West Africa Jurriaan Feijth^ Shonny Jackson-Hicks \ Warrick Crowe\ Matthew Finn\ Fiona Eddison\ Sandra Occhipinti^ 'Fugro Airborne Surveys, AngloGold Ashanti Geological interpretation of airborne potential fields data acquired by Fugro Airborne Surveys over the Air, Damagaram, and South Maradi provinces of Niger during 2005-2006 have elucidated on their complex geological history by allowing the first observation of coherent geological data under recent cover. The surveys were flown for the Ministry of Mines and Energy of the Republic of Niger under a support grant from the European Union. Niger contains diverse geological units that developed in disparate terranes, dating back as far as the Archean or Palaeoproterozoic, and spanning the entire cross-strike width of the Trans-Saharan Mobile Belt from Birimian greenstone belts (margin of the West African Craton) to the Air Massif (southeastern continuation of the Tuareg Shield from Algeria) to the Damagaram Inlier and South Maradi (Neoproterozoic schist belts of the Benin and Nigerian shields). Terrane amalgamation recorded in Niger took place during the Pan-African Orogeny (c. 750 - 500 Ma), forming the NE-trending linear Trans-Saharan Mobile Belt within Gondwana. The region was
continued next page..
Australian Earth Sciences Convention 2008
95
96 ABSTRACTS alphabetically by surname of presenting author
further deformed during Palaeozoic to Mesozoic tectonic with magmatic episodes recorded by extensive alkaline ring complexes that intrude the Air Massif and Damagaram Inlier, as well as, NW- and NE- trending conjugate brittle faults that may be associated with the amalgamation and/or subsequent break up of Pangea. Subsequently sedimentary rocks were deposited over the Trans-Sarahan Mobile Belt during the Palaeozoic. The prolonged tectonic history of Niger has provided many opportunities for fluid generation and resultant mineralisation. The recently acquired and interpreted potential fields data allows a more thorough assessment of the mineralisation potential within the Air Massif, Damagaram Inher and South Maradi Promontories, in some cases providing a more coherent look at the geological units than has previously been allowed to the paucity of outcrop in much of the area.
A three-dimensional Weights of Evidence Model for the Drummond basin in NE Queensland: quantitative assessment of controlling variables for epithermal Au Leonardo F e l W , Timothy Baker\ Margaretha Scott^, Melanie FitzelP and Kate Wilkinson^ ^School of Earth and Environmental Sciences, James Cook University, 4811, Townsville. ^Geological Survey of Queensland, Department of Mines and Energy, Indooroopilly, 4068, Brisbane In this contribution we report results of a mineral potential mapping study of the northern part of the D-ummond Basin and Anakie Inlier. These areas are well endowed with epithermal Au, containing economic mineral deposits such as Pajingo, Mount Coolon and Glen Eva, representing classical examples of low-sulphidation, adulariasericite type gold systems. WofE (Weights of Evidence) is a GIS approach that assesses the likelihood of finding a mineral deposit of the sought type, in the region of interest. The method uses fuzzy logic derived from expert systems to assign the Weights of Evidence necessary during the construction of binary predictors, which are subsequently combined using the Bayes rule of combination to produce a probability surface (G. Bonham-Carter, 1994, Geographic information systems for geoscientists: modelling with GIS, Pergamon, v. 13, 398 p.). When constructing a regional scale, 3D mineral potential model substantial subsurface geological information is desirable. However, such subsurface data is often limited, rendering the extension of this methodology in 3D difficult. We show possible solutions to this problem by using a range of geophysical inversion tools to estimate depth of intrusions, but also using geochemical regression to depth based on a
Australian Earth Sciences Convention 2008
combination of Factor Analysis and 3D WofE. Experimental analysis on the geochemical component was based on selected tables queried form the Terra Search database (training dataset). The advantage of using a 3D WofE model can be debated. However, initial results show that the use of geophysical information improves predictors (e.g., magnetic WORMS help distinguishing between real edges and false edges of intrusions, often misleading because of the surface relationships with cover sediments). Preliminary results show that 3D WofE may also provide a way to reconstruct geochemical signals undercover.
Geomorphology, crocodiles and mineralisation in Morobe Province PNG R. H. Findlay^
^Montagu Minerals mapping Pty Ltd, 44, Riawena Road, Tasmania 7018, Australia (mmmapping@hotmail com)
PNG is renowned as a Late MiocenePliocene gold province. Gold occurs commonly in fault-controlled epithermal systems associated with andesitic-dioritic stocks, some notable as Cu-Au porphyries, and others clearly as sub-volcanic intrusives. These deposits now lie in extremely rugged, heavily incised mountains. Past modelling of such deposits generally assumed that they formed in a geomorphologic setting akin to that of the present. To the contrary, extreme incision of meandering antecedent rivers through mountain ranges as high as 3 500m, the presence of Pliocene coralline limestones at altitudes of 2500m and local inversion of Pliocene fluvio-lacustrine to shallow-marine sedimentary basins to altitudes of 2 500m indicate very rapid Late Pliocene to Present uplift. Conclusive evidence for the Late Pliocene geomorphologic setting comes in the form of crocodile teeth in the Pliocene Otibanda Formation of the Bulolo depression, now surrounded by 2000-3000m high mountains These observations confirm that in Late Miocene to Pliocene times, much of the then forming PNG mineralised belt was a terrain with a low relief and wide alluvial plains flanked by swamps and marginal seas. Such a setting would permit the easy ingress of large volumes of water into the thermal systems producing mineralisation; indeed such deposits as the extremely rich volcanichosted Tolukuma mineral field could well have formed in an environment similar to that of Lihir today.
ABSTRACTS alphabeticafly by surname of presenting author
Age and provenance of the Owen Stanley Metamorphic Complex (East Papuan Composite Terrane) in Morobe Province, Papua New Guinea R.H. Findlavl G. Kopi^ I. Williams 3 ' Mineral Resources Authority, Private Bag, Port Moresby Papua New Guinea Montagu Minerals Mapping Pty Ltd, 44, Riawena Road, Tasmania 7018, Australia ^ Geoscience Australia, PO Box 378, Canberra, ACT, Australia.
U-Pb (SHRIMP) zircon-age patterns are reported for 4 samples of weakly schistose fossiliferous turbiditic sandstone and unfossiliferous greenschist facies pelite of the Owen Stanley Metamorphic Complex (OSMC) of Morobe province, PNG, a component of the East Papua Composite Terrane (EPCT) of Papua New Guinea. Despite the samples' geographical separation across an allegedley important and geophysically distinctive fault within the OSMC, as well as differences in protolith and metamorphic grade of the host rocks, their predominantly Cretaceous age indicates the likelihood that these metagreywacke units were derived from erosion of the Cretaceous Whitsunday Volcanic Province, forming the offshore extension of the New England Fold Belt. This would mean that the protoliths of these rocks, probably deposited in a submarine fan, were rafted north to accrete to PNG after the Paleocene opening of the Coral Sea and before the intrusion of the stitching Middle Miocene Morobe Granodiorite of Morobe Province and the PNG Highlands. The dated rocks lie north and west of the Ujacknji Complex, a series of Palaeocene oceanic basalt, gabbro and serpentinitic rocks whose origin is obscure but clearly formed in an ocean basin and which has been considered as part of the Papuan Ultramafic Belt which, in the north of the EPCT, overthrusts the OSMC. The zircon age data are also very similar to those from the Pahau terrane of New Zealand, allegedly derived from West Antarctica rather than from Queensland, Australia.
New zircon U/Pb dating from the Mt Coolon mineral district, northern Drummond Basin, Queensland, and implications for regional exploration targetting. R.H.Findlav^ S. Meffre^ T. Charlton^ ^Montagu Minerals Mapping Pty Ltd, 44, Riawena Road, Tasmania 7018 (mmmapping@hotmailcom) ^ CODES, University of Tasmania, Hobart, Tasmania 7001 (smeffreCd)Mtas. edu. au) ^Drummond Gold Pty Ltd, PO Box 844, Paddington, Queensland (tom@mtcoolon.com)
Six U/Pb-zircon ages from the Mt Coolon district of the Drummond Basin confirm the Cycle 1 rhyolitic to andesitic volcanic event at between 357-360Ma, with contemporaneous intrusion of 2-feldspar granitic dykes, sills and possibly sub-volcanic stocks. Two zircon U/Pb ages confirm that the magnetitiferous Manaman Granodiorite is of the age 305-3 lOMa. Part of this granodiorite is strongly cleaved and the cleavage dips at a shallow angle, possibly related to thrusting inferred cutting the Cycle 1 volcanics of nearby Mt Manaman. K/Ar dating, summarised from several mines in the northem Drummond Basin, suggests mineralisation at between 295-320 Ma, conceivably coincident with the Bulgonunna rhyodacitic volcanic event (circa 299Ma) and covering the age of the Manaman Granodiorite. Aeromagnetic data covering the Mt Coolon district highlight several hidden intrusives south of Mt Manaman. These carry the reversed magnetic signature of the PermoCarboniferous Kiamin superchron, part of which coincides with the Bulgonunna igneous event. The epithermal, quartz-hosted, auriferous Koala lode lies within a broad NWtrending sinistral strike-slip fault system (Coolon Fault System, or CPS) on the eastern side of the Manaman Granodiorite. The mineralisation in this fault system is associated with clay, silica and haematite alteration. If thrusting at Mt Manaman and the cleavage in the granodiorite accompanied strike-slip faulting, and the haematite alteration common in the area is related to intrusion of this magnetite-series granodiorite, then the period 295-3 lOMa i.e. the early part of the Kiamin superchron and extrusion of the continued next page... Australtan Earth Scfences Convention 2008
97
98 ABSTRACTS alphabetically by surname of presenting author
Bulgonunna Volcanics, is important for major mineralisation in the Drummond Basin. Thus our dating enables greater precision for regional exploration targetting. Tolukuma, PNG; the Structural Anatomy of a Classic Intra-Volcanic Epithermal Gold System. R.H. Findlay^ ^Montagu Minerals mapping Pty Ltd, 44, Riawena Road, Tasmania, 7018 (rhfindlay@hotmaiLcom) The remarkably rich Tolukuma mine of Central Province, PNG, lies on the southern tlank of a deeply eroded 34km by 24km Pliocene andesitic volcano, the Boundary Volcano. The presently productive ore bodies occur in tension fractures trending ESE and along a more southeasterly trending R shear formed within a sinistral strike-slip system whose main displacement zone constitutes the SSWtrending Tolukuma-Saki Fault System. Other sites known prospective for high-grade mineralisation occur more-or-less along strike of the Tolukuma Fault, within the Kimono Fault to the east and along the Saki Lineament 5km east of the Tolukuma Fault. The geometries of the veins and fractures in these other faults also specify sinistral strike-slip. Palaeostress analysis not only assists definition of the kinematics of the Tolukuma-Saki Fault System, but also has indicated the likelihood of an earlier strike-slip fault array, of probable overall dextral slip, in the Tolukuma mine area. This may provide previously unexpected targets for mineralisation. The recognition of the Tolukuma-Saki Fault System as a sinistral strike-slip array provides a sound predictive model for future systematic soil geochemical interpretation and for subsequent systematic trenching and drilling programmes. The recognition from regional and local geomorphology that this Pliocene volcano may well have been uplifted to its present altitude from close to sea-level since the Pliocene leads towards general modelling of the fluid flow involved in producing the deposit. For example, the Tolukuma Volcano may have formed in a setting such as that of Lihir.
Rapid uplift and fluvial impacts from the Finisterre and Sarawaget Mountains, Papua New Guinea R. H. Findlay^ ^Montagu Minerals Mapping Pty Ltd, 44. Riawena Road, Tasmania 7018, Australia (mmmapping @ hotmail com) The Finisterre and Sarawaget Australian Earth Sciences Convention 2008
Mountains
(FSM) of Papua New Guinea form a rapidly uplifting mountain chain on the northern margin of the Australian plate. Uplift rates are estimated locally using lithostratigraphic, fission-track and C'"^ data, as well as the age of a perched coral terrace on the northern side of the mountains. Uplift commenced at about 800 OOOyears BP at an average rate of about 6mm/yr, and on the southern side of the mountains this average rate has continued to the present day. In contrast, on the northern side of the mountains, after 320 OOOBP uplift slowed to the present average of 2-3mm/yr, yielding a tilted and now deeply incised peneplane across the FSM. Uplift has produced very deeply incised valleys, particularly on the southern flank of the mountains where the local micro-climate guarantees heavy rainfall and erosion in the afternoons and nights. The consequent oversteepening of the mountain slopes has produced gravitational instabilities which, exacerbated during periods of seismic activity, lead to periodic formation of landslide dams. The effects on strategic infrastructure of the failure of such landslide dams are presented.
Three-dimensional morphology of magmatic sulphides sheds light on ore formation, mantle melting and segregation of the Earth's core Dr Marco Fiorentini\ Dr Stephen Barnes\ Dr Peter Austin^ Dr Klaus Gessner^ '^, Dr Rob Hough^, Dr Andrew Squelch^ ^ Centre for Exploration Targeting, School of Earth and Geographical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia ^CSIRO Exploration and Mining, 26 Dick Perry Avenue, Kensington, WA 6151, Australia ^CSIRO Minerals, Conlon Street, Waterford, WA 6152, Australia ^Department of Exploration Geophysics, Curtin University of Technology The morphology of magmatic sulphides in igneous cumulates is controlled by the wetting properties of sulphide liquids against silicates. The formation of nickel sulphide ores, the behaviour of sulphide liquids during mantle melting, and potentially the segregation of the Earth's core, are all controlled by the abihty of sulphide liquids to migrate through the pore space of partially molten silicates. Three-dimensional X-ray tomographic images of sulphide aggregates in komatiites indicate that sulphide liquids have limited tendency to wet olivine crystals, forming interconnected networks only in the absence of silicate melt. Consequendy, the ability of sulphide liquids to migrate through the pore space of olivine cumulates is restricted. It is therefore unlikely that sulphide droplets can be
ABSTRACTS 99 alphabeticafly by surname of presenting author
entrained and carried from the mantle. Our results support the hypothesis that segregation of the Earth's core took place from a magma ocean, rather than by percolation of sulphidic melt through partially molten mantle.
Role of volatiles and metasomatised subcontinental lithospheric mantle in the genesis of magmatic Ni-Cu-PGE mineralisation: a case study from the Valmaggia ultramafic pipe, IvreaVerbano Zone (NW Italy) M.L. Fiorentini^ and S.W. Beresford^ ^ Centre for Exploration Targeting, UWA, Crawley,
WA 6009, Western Australia
In-situ trace element and isotopic data of hydromagmatic phases from the Valmaggia gabbrowehrlite pipe shed new light on genetic models for the formation of orthomagmatic Ni-Cu-PGE deposits in the Ivrea-Verbano Zone (NW Italy). Volatiles implicated in the formation of hydromagmatic phases are not hydrothermal and did not derive from crustal assimilation. Low boron concentrations exclude the implication of fluids derived from dehydration of a subducted slab and indicate an origin from mantlederived juvenile water. Metasomatism introduced elevated contents of alkalis, Cu, PGEs and S into the depleted mande of the Ivrea-Verbano Zone. Increased water activity caused the harzburgite to undergo partial melting, thus producing pockets of volatile-rich sulfide-bearing ultramafic magma that evolved to form independent intrusions that host NiCu-PGE minerahsation. These conclusions corroborate the idea that fundamental processes that lead to the formation of Ni-Cu-PGE deposits do not occur upon emplacement during the last stages of crystallisation of the host rocks (e.g. sulfur addition, crustal assimilation), but are intimately associated with processes that occurred at source in the subcontinentallithospheric mantle. Therefore, we believe that some aspects of current orthomagmatic ore genetic models should be revisited, and the prospectivity of numerous areas should be reevaluated.
The Shear Wavespeed Structure of the Australian Lithosphere: Is it Compatible with Physically Based Models? Stewart Fish wick ^ Anya Reading^ ^ Department of Geology, University of Leicester, University Road, Leicester, LEI 7RH, United Kingdom, (sfl30@le.ac.uk) School of Earth Sciences and Centre of Excellence in Ore Deposit Research, University of Tasmania, Hobart, TAS 7001, Australia. (anya. reading @ utas. edu. au)
Surface wave tomography has highlighted a region of slow seismic wavespeed in the uppermost mantle beneath central Australia. This zone of slow wavespeeds is underlain by a region of faster wavespeeds, more typical of continental lithosphere. The apparent layering of the velocity structure, and the strong positive wavespeed gradient with depth, is difficult to explain in terms of conventional peridotite lithology and typical steady-state continental geotherms. Possible explanations for the slow velocities include an unusual distribution of heat producing elements within the crust, however the fast velocities beneath are likely to remain difficult to explain. Alternatively, a shallow lithosphere containing a significant proportion of minerals with low seismic velocities (such as amphibole), overlying a continental root with a more conventional lithology, could explain the observed seismic wavespeeds. The anomaly is located directly beneath the zone where the Australian cratons amalgamated in the Proterozoic and where, subsequendy, there have been periods of intraplate tectonic activity. This suggests a correlation between the prolonged history of deformation and an unusual lithospheric structure. It is interesting to note that recent work, looking at various cratonic regions worldwide, indicates that models of constant composition throughout the lithosphere do not fit the observed seismic dispersion characteristics. A more complex model of lithospheric structure may be required to fit the seismic data, and central Australia may simply be an example where this structure is accentuated in the surface wave tomography.
Application of Geomodeller in the Drummond Basin, Queensland Melanie Fitzell^ Margaretha Scott \ Kate Wilkinson^ Owen Dixon^ ^Geological Survey of Queensland, Department of Mines and Energy, Indooroopilly, 4068, Brisbane (melanie.fitzell@dme. qld.gov.au) The Queensland Government, through the Department of Mines and Energy is actively seeking to improve exploration activities across the state in target areas that have significant mineral and energy potential. The Drummond Basin in northern Queensland is one such area with potential for economic deposits of low-sulphidation epithermal gold. In 2003 the Geological Survey of Queensland began the Drummond Basin Project. The project initially involved the collection of mineral occurrence data and remapping outcropping geology at 1:100,000 scale. Subsequent stages included mineral resource assessment and 3D geological modelling. Two 3D models were initiated; an in-house continued next page... Australian Earth Sciences Convention 2008
100
ABSTRACTS aiphabeticatly by surname of presenting autnor project using Geomodeller and a joint Geological Survey of Queensland (GSQ) - James Cook University (JCU) project using GoCAD. The main aims of the Geomodeller project were to use 2D and 2.5D geological mapping to gain a better understanding the structural relationships within the basin and 3D geological architecture. Geomodeller software was selected for several reasons including, its ease of use, the ability to readily revise models as new data becomes available and its unique functionality of potential field modelling. The joint JCU-GSQ project was aimed to produce a model with functionality to support statistical analysis that could be used to explore relationships between geological variables and mineralisation. The Geomodeller project was constructed over the north western portion of the Drummond Basin to maximise gains of working with a range of datasets (new mapping, seismic surveys, drilling information and potential field data including newly generated 'worm' datasets). The regional scale of the project necessitated the simplified representation of stratigraphy and fault networks. Due to the limited number of mass density and magnetic property data measurements currently available across the project area, further work will focus forward modelling on areas within the model where geophysical contrasts occur and significant structures occur. Future work will include testing the inversion capabilities of Geomodeller.
Surface area of emerged land and depth of mid-oceanic ridges in the Archean Nicolas Patrice Rey^
Nicolas
Coltice^'^
^ Laboratoire de Sciences de la Terre, Ecole Normale Superieure de Lyon, Universite de Lyon, CNRS UMR 5570, 46 allee d'ltalie, 69364 Lyon CEDEX 07, France (N.F: nicolas.flament@enslyon.fr) Universite Lyon 1, Universite de Lyon, France (N.C: coltice@univ-lyonLfr) ^ Earthbyte Group, School of Geosciences, The University of Sydney, Sydney, NSW 2006 (prey@geosci. usyd. edu. au) The secular cooling of the Earth's mantle implies a progressive change in the isostatic balance between continents and oceans, consequently changing the oceanic bathymetry, the surface area of emerged continental crust and the depth of midoceanic ridges. These variables are of fundamental importance to plate tectonic processes and to the geochemical coupling between mantle, continental crust, atmosphere and ocean. We developed a numerical model to evaluate the above three parameters as functions of ocean volume, mantle temperature and continental fraction. We show that a reduced continental area in the Archean is compatible with constant continental Austraiian Earth Sciences Convention 2008
freeboard (d=300m), as long as the mantle temperature did not exceed its modern value by more than 150K. Our model predicts that during most of the Archean, the surface area of emerged continental crust was approximately 1% of the Earth's surface. In the late Archean, many cratons thickened due to the accumulation of greenstone covers 5 to 15km thick. Our model shows that this thickening results in an increase in the surface area of emerged continental crust to 5% of the Earth's surface. This is consistent with widespread mid- to late-Archean submarine continental flood basalts, and with the appearance and strengthening of the geochemical fingerprint of felsic sources in the lateArchean sedimentary record. We show that this emergence was also associated with the enlargement of shallow-water continental platforms, in agreement with the geological record. We further argue that Archean mid-oceanic ridges were never more than 800m shallower than present. Consequently, hydrothermal vents at mid-oceanic ridges have been a very stable ecological niche throughout the Earth's history.
The Uralla Magmatic Centre: Presentation of Plutonic & Volcanic Rocks Representing an Upper Crustal Section of Some 8km R.H. Flood^ and S.E.Shaw^ ^GEMOC, School of Earth and Planetary Macquarie University, 2109, NSW, (rflood @ els. mq. edu.au)
Sciences, Australia
At Uralla, in southern New England, the combined effects of caldera collapse and regional tilting have preserved: 1) Early Triassic lavas; 2) a two-pyroxene dacite tuffacite marginal ring-dyke that is microstructurally zoned inward to a granodiorite pluton and; 3) the zoned Uralla zoned pluton. Whole-rock and mineral geochemistry, Sr isotopes and single-grain zircon Lu-Hf isotopes indicate that all of these units are geochemically and isotopically similar and have the transitional I-S type character that is a characteristic of the Uralla supersuite and new zircon Hf/Hf data offer additional support for the conclusion argued earlier that the very mafic dioritic rocks of the Uralla zoned pluton are cumulates. The association of the intrusive fragmental rocks that grade into a porphyritic granodiorite indicate ignimbritic eruptions can be sourced from magma chambers many kilometers below the surface. For this group of spatially and geochemically related volcanic, subvolcanic and plutonic rocks we propose the term Uralla Magmatic Centre to indicate the strong connections of these different rock types. In that sense, we see similarities to the term "intrusive series" used by Bateman in the Sierra Nevada Batholith for spatially and genefically related granific rocks (but where no volcanic rocks
ABSTRACTS 101
aiphabeticaHy by surname of presenting author
were preserved). The size of the Uralla zoned pluton indicates that between the initial eruption of the first lavas and the emplacement of the Uralla pluton, several km of volcanic (ignimbritic?) rocks must have been deposited above those still-preserved lavas in a situation that may have matched the thick volcanic sequences that presently occupy much of the Taupo Volcanic Zone. It would seem that the volcanic rocks are preserved only near the comagmatic pluton where they may have been thickest as well as down faulted
Reinterpretation of high-temperature metamorphism within a continental back-arc setting for the Broken Hill Block, NSW Caroline Forbes Pete Betts\ Dave GilesRoberto Weinberg^ ^School of Geosciences, Monash University, Melbourne (caroline.forbes@adelaide.edu.au) Current address: Centre for Mineral Exploration Undercover, School of Earth and Environmental Sciences, University of Adelaide Accounting for a mid-crustal hightemperature/low-pressure metamorphic regime where contemporaneous, voluminous magmatism is absent and peak metamorphism appears synchronous with crustal shortening is difficult, as this regime is typically associated with mid- to high-pressures, and also calls for introduction of an anomalously high heat source at shallow crustal levels. An example is the Broken Hill Block (BHB), where regional hightemperature/low-pressure granulite facies metamorphism is associated with crustal shortening during the Olarian Orogeny ~ 1.6-1.58 Ga. We have reinterpreted the pre-Olarian history of the BHB, and suggest that peak high-temperature metamorphism resulted from burial of anomalously hot rock packages, and involved at least two episodes of extension closely followed by shortening. Lithospheric geothermal gradients within the BHB were initially elevated during early rifting and deposition of lower BHB sedimentary sequences ~1.71-1.67 Ga (e.g. Page et al., 2005, Economic Geology, v. 100, p. 633). These sequences were then buried during sag-phase sedimentation to ~1015 km. A second, transient, mid-crustal extensional event occurred at -1.62 Ga (Forbes et al., 2007, J. Geology, v. 115, p. 691) and was associated with elevated geothermal gradients (~41-61°C km"'). This event maintained the elevated geotherm that was inherited from earlier rifting. The BHB was then buried to -17.5 km (~5 kbar). Burial of the hot rock packages resulted in temperatures increasing to conditions of peak, low-pressure granulite facies metamorphism (~740°C, ~5 kbar) at -1.60 Ga. High-temperature shear zones were active during
this time. The BHB then underwent intense shortening during the Olarian Orogeny. Tectonic switching has commonly been associated with a back-arc environment, where extension may be a response to slab roll-back, and a switch to compression is caused by arrival of anomalously buoyant material at the subduction site (e.g. Collins, 2002, Geology, v. 30, p. 535). The interpreted tectonic environment for the BHB is a continental back-arc setting located in the overriding plate of a subduction zone along the southern margin of Proterozoic Australia.
Metamorphism of the Mount Woods Domain, Gawler Craton Caroline Forbes^ Dave Giles \ Martin Hand^, Neil Chalmers^ Rian Dutch?, Pete Betts^ ^Centre for Mineral Exploration Undercover, School of Earth and Environmental Sciences, University of Adelaide, Adelaide (caroline.forbes@adelaide.edu.au) Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, Adelaide ^Primary Industries and Resources South Australia, 101 Grenfell St, Adelaide "^School of Geosciences, Monash University, Melbourne The Mount Woods Domain (MWD) in the northeastern Gawler Craton is highly prospective for FeO-Cu-Au deposits (including association with the recently discovered Prominent Hill FeO-Cu-Au orebody) and has been explored for Broten Hill-type Pb-Zn-Ag mineralisation. Although of economic significance, the MWD is geologically poorly understood as it is mostly overlain by extensive cover sequences. Limited work conducted in the area shows a complex history involving early sedimentation to -1740 Ma (e.g. Fanning et al., 1988, Precambrian Research, v. 40/41, p. 363), metamorphism and deformation during the Kimban Orogeny (-1730-1710 Ma) and possibly younger sedimentation to -1640 Ma (Holm, OZCHRON). Metamorphic zircon overgrowths yield an age of -1590 Ma (e.g. Holm, OZCHRON; Chalmers 2007, PIRSA Report Book 2007/20), which is approximately contemporaneous with mineralisation at Prominent Hill and extrusion of the nearby Gawler Range Volcanics (-1592 Ma; e.g. Fanning et al., 1988). A garnet-cordierite-spinel bearing pelite exposed in the northern MWD was used to reconstruct the prograde pressure-temperature path. Porphyroblasts interpreted to have been andalusite indicate that early phases of prograde metamorphism occurred at conditions of -1.8-4.2 kbar and -510630°C. As a result of subsequent heating, andalusite
continued next page... Australian Earth Sciences Convention 2008
102 ABSTRACTS alphabetically by surname of presenting author
porphyroblasts are completely replaced by cordierite-spinel symplectites that were isolated from the remainder of the bulk rock by cordierite moats. Garnet was also a product of prograde heating. Peak metamorphism attained conditions of - 4 . 7 kbar and 7 6 5 T . Associated geothermal gradients are elevated, and are estimated to be km'^ during the early stages of metamorphism, and ~45°C km'^ during peak metamorphism. High-temperature/low-pressure metamorphism, significantly elevated geothermal gradients and complex -1600-1580 Ma tectonothermal evolutions are not uncommon within other mineralised Proterozoic Australian orogenic belts (e.g. Broken Hill, Mt Isa, Olympic Dam). The commonality of these geological histories, as well as the occurrence and widespread nature of mineralisation brings into question the tectonic context of such high-temperature/low-pressure metamorphic regimes.
Fluid Flow in 3D Strike-Slip Fault Systems Arianne Ford^ ^ Econonic Geology Research Unit, James Cook 4811, Australia. University, Townsville, Qld (Arianne.Ford@jcu.edu.au). This study illustrates the effect of varying fault geometry using a three-dimensional finite difference code, whereas previous studies focused on twodimensional models. Utilizing an existing GIS fault database of the Mount Isa Inlier, the most common trend of the major structures in the Western Succession was found and set as the default fault geometry for the numerical models. Using this default geometry, a series of fault bend and fault jog geometries were modelled and the dilation and integrated fluid flux outputs evaluated. Through variation of fault dip, fault width, bend/jog angle, bend/jog length, inclusion of a cross-cutting fault and contrasting rock types, the results were examined to determine which values for a particular parameter produced the greatest dilation and integrated fluid flux within the models. Results demonstrate that both fault bend and fauh jog models with a low fault dip or a wide fauU produce greater maximum dilation and integrated fluid flux. Fault bend models generate higher maximum dilation and integrated fluid flux as the bend angle increases, whereas the fault jog models produce higher maximum values as the jog angle decreases. Maximum dilation and integrated fluid flux values are found in fault bend models with a longer bend, and in fault jog models with a shorter jog. The inclusion of a crosscutting fauh or a contrast in rock type is found to increase the maximum dilation and integrated fluid flux values in both fauh bend and jog models. Some resuhs obtained oppose the conventional ideas relating to restraining and releasing bend and jog
Australian Earth Sciences Convention 2008
geometries. Using the maximum values of dilation and integrated fluid flux, the fault geometry parameters varied in this study can be ranked in order of importance. These results can be used in field campaigns to focus on areas with the most favorable fault system parameters.
Do strain-rates in deep ductile shear zones reflect seismogenesis at surficial levels of the same movement zone? Marnie Forster', Gordon Lister^ ^ Research School of Earth Sciences, The Australian National University, Canberra 0200 Australia It has become evident that large-scale ductile shear zones play a role during seismogenesis, e.g., defining the down-dip extension of seismicallyactive faults. Rapid movements might take place in such zones as the result of large earthquakes, including motions normally referred to as pre-slip or after-slip. Movements may be sufficiently rapid to cause temperature rises that affect the component minerals, and lead to metamorphic reactions and growth of new mineral assemblages. Importantly, such events would explain very short-lived thermal pulses we infer in orogenic belts. There is much data that can be interpreted in terms of the effects of such short-lived thermal pulses. The survival of older mineral paragenesis suggests that the duration of any thermal pulse was not long enough to allow transformation of metamorphic minerals to new parageneses, except where deformation and fluids facilitate the process, usually within the shear zone itself. Similarly it can be supposed that the duration of any thermal pulse is not long enough to allow complete diffusional loss of argon from relict mineral grains, which therefore display anomalously older ages, except where these relicts have been substantially deformed and/or recrystallized. These concepts can be tested using Kfeldspar geospeedometry to estimate the duration of thermal events. Preliminary data suggest that the candidate shear zone operated at rates appropriate to periods of pre-slip or after-slip related to major seismic events. P-T conditions that allow growth of garnet-hbiotite could endure for only short periods, estimated here as not exceeding one thousand to ten thousand years during the total five million year operating life of this ductile shear zone. Ongoing research is necessary if we are to achieve more fundamental understanding of the geodynamic context of natural hazards. Further modelling may reveal constraints on the recurrence interval of individual movements that sum to effects as mentioned above.
ABSTRACTS alphabetically by surname of presenting author
Orogeiv-Scale Tectonic Shuffle Zones. Mamie Forster^, Gordon Lister^ ^ Research School of Earth Sciences, The Australian National University, Canberra 0200 Australia Orogen-scale or even lithosphere-scale shuffle zones may accommodate major reversals of movement associated with tectonic mode switches, with relative displacements potentially exceeding 100-200 km. Such zones may be more prevalent in orogens than is now apparent. This contribution highlights some potential examples, and establishes some geodynamic constraints as to their evolution. We think tectonic shuffle zones arise because tectonic mode switches lead to large-scale thrusts that are later transected by extensional detachments, or vice versa. For example extensional detachments that form after a thrust event do not precisely follow the trajectory of the older thrusts. Shuffling caused by reversal of the opposing sequential movements on these structures then causes thin relict lenses of high-pressure rock to be stranded between adjacent tectonic slices, with each slice reflecting different PT histories. Thus we can explain a thinly sliced tectonometamorphic stratigraphy: a feature common to most coherent high-pressure and ultra-highpressure terranes. This interpretation is subject to dispute, in particular since high-pressure tectonic melanges can also be associated with such structures. Channel flow, corner flow and extrusion hypotheses, at first sight, seem able to explain many of the observed characteristics of these complex structures. These competing hypotheses focus attention on the nature of possible movements within a subduction channel, or within a ductile extrusion channel triggered by softening as the result of high-grade metamorphism and/or anatexis. In contrast, the concept of a tectonic shuffle zone arises out of consideration of the nature of the movement zones that must result if adjacent bodies of rock are subject to large (i.e. > -100 km) horizontal components of relative motion in one direction followed by large horizontal components of motion with opposite sense. This is an important distinction, and a significant issue, since tectonic shuffle zones seem common aspects of the structural geology of orogens.
The Accretion of North & South Gondwana: Evidence from U-Pb Ages & Hf-isotopic Compositions of Detrital Zircons from the Damara Orogen, Namibia D a v i ^ A ^ F o ^ ^ Ben. D. Goscombe^, Paul A. Mueller^ David R. Gray^, Joseph G. Meert^
^ Department of Geological Sciences, University of Florida, Gainesville, FL 32611, USA (dafoster@ufl.edu) School of Earth and Environmental Sciences, University of Adelaide, Adelaide SA 5005 School of Earth Sciences, University of Melbourne, Melbourne VIC 3010 and Geostructures Pty. Ltd. The breakup of Rodinia and accretion of Gondwana define a one of the most critical periods in Earth history both tectonically and biologically. In recent years, it has become particularly apparent that proper identification of ancient suture zones is critical to accurately defining supercontinent cycles and identifying the nature of juxtaposition of cratons in the context of global geodynamics. The configurations of continental fragments within Rodinia, the dispersal of these fragments, and their subsequent amalgamation to form Gondwana remain some of the more profound questions in continental evolution, geodynamics, and paleogeography. There are two very different hypotheses for the relationship between the Congo and Kalahari cratons, which now make up southern Africa and comprised the core of Gondwana. These cratons are presently separated by the Neoproterozoic-Cambrian Damara-LufilianZambezi orogenic system. The Congo and Kalahari cratons may have been located in different parts of Rodinia (or not in Rodinia at all) and then collided when Gondwana formed. Alternatively, Congo and Kalahari may have been together from the time that Rodinia formed and in roughly the same relative positions as they are today, separated by a small Red Sea-like basin at Rodinia breakup, and reconnected upon amalgamation of Gondwana. Unfortunately, there are no reliable paleomagnetic data for Kalaharia and only limited data from Congo for late Neoproterozoic time. The results of preliminary analysis of U-Pb ages and Hf-isotopic compositions of detrital zircon from Neoproterozoic metasedimentary rocks within the Damara orogen show distinct sources from the Congo and Kalahari cratons and as well as other Gondwanan fragments. These data constrain the accretionary history of north and south Gondwana and suggest the presence of a significant ocean between these cratons in Neoproterozoic time.
The southwestern Laurentian lithosphere in the northern Rockies, USA: crustal provinces, plutonic imaging, and seismic structure David A. Foster^ Paul A. Mueller \ Raymond Russo', David W. Mogk^ ' Department of Geological Sciences, University of Florida, Gainesville, FL 32611, USA (dafoster@ufl. edu) ^ Department of Earth Sciences, Montana State University, Bozeman MT 59717 USA
continued next page...
Austrafian Earth Sciences Convention 2008
103
104
ABSTRACTS alphabetically by surname of presenting author
Precambrian provinces and boundaries in the northern Rocky Mountains, USA, include the Archean Wyoming craton, the Paleoproterozoic Selway terrane (2.4-1.6 Ga), Paleoproterozoic Great Falls tectonic zone (1.86-1.77 Ga), Archean Grouse Creek block, Mojave province, Mesoproterozoic Belt basin, and Neoproterozoic passive margin. These Precambrian lithospheric elements are host to Cretaceous-Eocene igneous provinces including calc-alkaline mesozonal plutons (Idaho batholith), epizonal plutons and volcanic rocks (e.g. Boulder batholith, Challis-Absaroka volcanics and plutons), and the central Montana Alkalic Province, as well as the Cretaceous-Paleocene Cordilleran thrust belt and Cenozoic Rocky Mountain basin and range. Current geophysical, elemental and isotopic data indicate that the crust is vertically stratified in composition and age. The lower crust of some older Precambrian provinces is more mafic and apparently younger than the surface rocks, due to underplated mafic material added during the late Archean, Paleoproterozoic, and/or Mesoprotoerozoic. Hfisotopic compositions and model ages of inherited zircons, along with whole-rock Nd, Sr, and Pb isotopic compositions of Cretaceous metaluminous granitoids show that the mafic lower crustal layer is mosdy Paleoproterozoic. Analysis of regional seismic tomography data and SKS splits for depths to -250 km indicate that the ArcheanPaleoproterozoic lithosphere of southwestern Laurentia has been recently and significandy modified, and may be delaminating. Subcontinental lithosphere extends to depths of -250 km in the eastern part of the Wyoming craton, but only -75 km in the west. At intermediate depths across the geographic center of the Wyoming craton mantle a sill of mantle with asthenospheric velocity is present with lithospheric velocities beneath. The Archean root of the craton may be delaminating from west to east and associated with the Yellowstone hot spot or Laramide metasomatism along ancient structures.
Key Controls on the Genesis of Giant Magmatic Sulfide Systems with Special Reference to Source Controls and Multistage Sulfide Saturation. J. G. Foster^ ^ CODES Centre of Excellence in Ore Deposits, University of Tasmania, Hobart, Tasmania, 7001(Jeffrey.Foster@ UTAS.edu.au), Magmatic sulfide deposits occur throughout geological dme and in a range of tectonic settings. Many deposits are found in associadon with preserved high-level Large Igneous Provinces (LIPS) or their exposed root zones. The difference in tectonic setdng is also reflected in the chemistry of donor melts which is diverse both in respect to inidal MgO content and level of trace-element enrichment. Australian Earth Soiences Convention 2008
Data from four deposits (Kambalda, Jinchuan, Voisey's Bay and Noril'sk-Talnakh) highlight the variability in melt composition and sulfide processing. The compositions of magmatic sulfides record the complex evolution of these deposits and can be used to illustrate a number of processes that ultimately lead to the formation of a world-class ore system. Critically sulfide undersaturated melts are not required to form a giant ore system but rather multistage sulfide saturation and or repeated injection of sulphide laden melts into physical traps are the dominant controls on the economic viability of many major magmatic sulfide deposits.
The Kararan Orogeny - a link between the Proterozoic North Australian and South Australian cratons? Geoff Fraser\ Anthony Reid^ ^Onshore Energy and Minerals Division, Geoscience Australia, GPO Box 378 Canberra ACT, 2601, Australia (Geoff.Eraserici),2a.gov.cm) ^ Geological Survey Branch, Primary Industries and Resources South Australia, GPO Box 1671, Adelaide, SA 5001, Australia Numerous accretionary -dominated models for Australian Proterozoic evolution have been published in the past decade. Several of these models propose radically contrasting relationships between the North, South and West Australian cratons. Discriminating between contrasting models requires improved tectonic understanding of regions forming the margins to each of these three Australian cratonic elements. One such marginal region is the north-western Gawler Craton. This region, while poorly understood due to lack of outcropping basement rock, apparently consists of several tectonic slices, each with contrasting ages of constituent rocks and contrasting metamorphic histories, separated by NE-trending shear zones. The most northwesterly of these tectonic slices, known as the Nawa Domain, consists of high-grade metamorphic rocks proposed to have been metamorphosed during the Kararan Orogeny. The Kararan Orogeny is regarded by some authors as the resuh of continental collision on the northwest margin of the Gawler Craton. Timing of the Kararan Orogeny is poorly constrained to between -1650 and 1550 Ma. This is a period that, elsewhere in Proterozoic Australia, resulted in the extensive Gawler Range Volcanics and Hiltaba magmatism, the Olarian Orogeny, accretion of the Warumpi Province to northern Australia, the Chewings Event, and the Isan Orogeny. The Kararan Orogeny may have been the last major orogenic event to have affected the South Australian Craton. Improved resolution of the timing, spatial extent and metamorphic character of the Kararan
ABSTRACTS alphabetically by surname of presenting author
Orogeny will allow meaningful comparison of Proterozoic events in the northwest Gawler Craton with other broadly contemporaneous tectonic activity in Australia. Such comparisons will provide important tests of published tectonic models for Proterozoic Australia. Here we provide new age information, and review existing constraints on the timing, spatial extent and metamorphic character of this missing piece in the Australian Proterozoic puzzle.
situations such as boundaries or mineralization. Our analysis shows that a SOM data mining approach can provide value and assist in the integrated analysis of petrophysical properties derived from the inversion of geophysical data.
Preliminary Results of a Self Organizing Map Approach to the Integrated Analysis of Petrophysical Property Data from the Ultramafic-Hosted Seagull PGE-Ni-Cu Prospect, Lake Nipigon, Ontario, Canada
Edmund L. Frost lll\ Charles Kerans^
Stephen J. Fraser^ and Jane H. Hodgkinson^ ^CSIRO Exploration & Mining, PO Box 883 Kenmore, 4069 Australia. (Stephen.Fraser@csiro.au) ^CSIRO Exploration & Mining, PO Box 883 Kenmore, 4069 Australia. (Jane.Hodgkinson @ csiro. au) During the nineties, algorithms were developed to invert airborne or ground-based geophysical survey data to recover 1-D, 2-D, or 3-D images of the earth's petrophysical properties. These petrophysical images were a significant step forward as they may be associated with sub-surface lithology, structure and even mineralization. However, models from these inversions tend to be smooth, and it is often not obvious how variations in these physical property models definitively relate to geology. The 3-D distribution of a particular petrophysical property does not necessarily direcdy correspond to a particular geological unit. Our objective in this investigation was to determine whether more meaningful geological domains could be derived via a combined analysis of two or more petrophysical properties. Consequently, we have applied a self organizing map (SOM) approach to conduct an integrated analysis of density and magnetic susceptibility voxel data in an attempt to better define geological patterns and units of significance at the ultramafic-hosted Seagull PGE-Ni-Cu prospect. Because SOM looks for both linear and non-linear relationships between the input petrophysical properties, the segmentation or "domaining" that a SOM analysis provides is more likely to correspond to natural associations related to geology than more traditional statistical approaches. Our results indicate that SOM provides a means to identify patterns related to the petrophysical responses of particular units or lithologies. SOM can also identify anomalous voxels, or outliers that may relate to atypical
Controls on Syndepositional Fracture Patterns, Devonian Reef Complexes, Canning Basin, Western Australia
^ConocoPhillips Subsurface Technology Group, 600 N Dairy Ashford, Houston, Texas, USA ^ John A. and Katherine G. Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas, USA Syndepositional deformation in carbonate platforms is often acknowledged to be stratigraphically controlled; however, it remains unclear how variations in stratigraphic architecture affect syndepositional fracture patterns. This study integrates outcrop and remote-sensing data from the Canning Basin's Devonian reef complexes to test the hypothesis that syndepositional fracture attributes (orientation, intensity, and spatial arrangement) are a function of depositional facies, position along a carbonate platform, and platform-margin trajectory. Three basic control types are proposed for the generation of syndepositional fractures: gravitational instability and compaction (Type I), differential compaction over antecedent topography (Type II), and active regional tectonic deformation (Type III). Strong variations in syndepositional fracture intensity, extension, and spatial arrangement are observed with changes in lithofacies. Evidence of temporal evolution of the mechanical properties of the Devonian reef complexes is presented, with early-lithified strata effectively behaving as a single mechanical unit during syndepositional fracture development, while secondary fractures are strongly affected by bed-scale mechanical heterogeneity introduced by progressive diagenesis. Syndepositional fracture intensity is shown to vary systematically with changes in platform-margin trajectory; with high fracture intensities observed in strongly progradational platforms and decreased fracture development in aggradational and retrogradational platforms. By deriving fracture intensity as a function of observable criteria, such as platform-margin trajectory, the results presented here take a significant first step toward developing predictive relationships between syndepositional fracture development and stratigraphic architecture in the subsurface using seismic or well data.
Australian Earth Sciences Convention 2008
105
106 ABSTRACTS aiphabeticaiiy by surname of presenting author
Dynamic permeability in fine-grained ultramylonites - implications for fluid flow in mid-crustal shear zones Florian0 Fusseis\ Klaus Gessner\ Rob 19 >9 Hough , Klaus Regenauer-Lieb ' , Jie Liu , Oliver Gaede\ Holger Stuenitz^ ^ School of Earth & Geographical Sciences, University of Western Australia, (fusseis@cyllene. uwa. edu. au) 2 CSIRO Exploration & Mining 3 Department of Geology, University of Tromso, Norway Fine-grained ultramylonites form the mid-crustal cores of tectonic boundaries and are likely to act as pathways to fluids in the ductile middle crust. Deformation in these ultramylonites is commonly accommodated by a number of competing deformation mechanisms. The most efficient mechanism controls the microstructure and thus fluid flow. Diffusion-assisted viscous grain boundary sliding is a highly efficient deformation mechanism especially when a fluid eases diffusion along grain boundaries. However, to dominate deformation, the mechanism requires the maintenance of small grain sizes (< tens of microns). This fundamentally disagrees with the rocks' attempt to minimize its total surface energy by grain growth. In polymineralic rocks, an anti-clustered mixing of the individual mineral species (i.e. a minimum number of boundaries between the same minerals) inhibits grain growth and thus facilitates viscous grain boundary sliding. However, the formation of anticlustered mineral phase mixtures is still poorly understood. We explore a mechanism to mix solid mineral phases by heterogeneous growth of unlike minerals from a fluid in pores that open as grains slide past each other. We demonstrate how porosity and permeability evolve dynamically during the progressive formation of a fine-grained ultramylonite. Our 3D data provide details on the activation of viscous grain boundary sliding as the mylonite forms. The investigation improves our understanding of the mutual influence of viscous grain boundary sliding and fluid flow in actively deforming rocks in the ductile middle crust.
Australian Earth Sciences Convention 2008
Cenozoic biogeographic evidence for West Pacific Warm Pool formation and the initiation of the Kuroshio and Leeuwin Currents. Stephen J. Gallagher^*, Malcolm W. Wallace ^ Chung Leong Li\ Belinda Kinna\ John T. Bye\ Kazumi Akimoto^, Masayuki Torii^ ^The School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia (^Corresponding author's email: sigall(d),unimelb. edu. au). ^Centre for Marine Environmental Studies, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-855, Japan email address: sjgall@unimelb.edu.au Indo-Pacific (pale)oceanographic studies have primarily focussed on deep sea records charting Cenozoic climate and ocean change. Equivalent shelf margin studies are rare, even though these regions are likely to preserve evidence of shelf influencing currents such as the Leeuwin and Kuroshio Currents. We have compiled the Miocene to Recent distribution of the subtropical to tropical shelfal benthonic foraminifera: Heterolepa margaritiferus, Pseudorotalia schroeteriana, Pseudorotalia indopacifica and Asterorotalia gaimardii in the Indo-Pacific. These species can be used to document the evolution of the West Pacific Warm Pool, the Indonesian Throughflow and its related extra-tropical currents. The data reveals the presence of a central West Pacific Warm Pool biogeographic province from 10 to 4.4 Ma from the equator to 26°N. Indo-Pacfic foraminiferal species migrated to 35°N after 3 Ma with the initiation of the "modern" Kuroshio Current coinciding with the intensification of the North Pacific Gyre and Northern Hemisphere Icesheet expansion. From 10 to 4.4 Ma biogeographic connectivity between the Pacific and Indian Ocean was minimal due to a tectonically restricted Indonesian Throughflow. This caused warm water to pile up in the central Pacific forming an initial West Pacific Warm Pool. From 4.4 to 4 Ma limited Indonesian Throughflow allowed the migration of these Indo-Pacific species to the northwest Australian shelf Full northwest Australian connectivity with the West Pacific Warm Pool was established from 1.6 to 0.8 Ma during the Middle Pleistocene Transition. This was caused by a tectonically unrestricted and stronger Indonesian Throughflow leading to the initiation of the Leeuwin Current. The reduction in abundance and regional extinction of Indo-Pacific species in northwest Australia after 0.8 Ma may be related to the combined effect of glacial/interglacial cycles and uplift in the Indonesian archipelago causing Indonesian seaway restriction during the Late Pleistocene.
ABSTRACTS 107 aiphabeticafiy by sumame of presenting author
Late Cretaceous D^soxia in a Southern High Latitude Deltaic to Outer Shelf Succession, the Otway Basin, Southeastern Australia M ^ G a l l a g h e r ^ ' ^ D. Taylor^ M . A p t h o r p e ^ J. D. Stilwetf, C J . B o r e h a m ^ G.R. H o l d g a t e ^ M . W . W a l l a c e ^ P.G. Q u i l t / ^School of Earth Sciences, The University of Melbourne, Victoria 3010, Australia School of Earth & Geographical Sciences (Geology; M004). The University of Western Australia, 35 Stirling Highway, Crawley Western Australia 6009, Australia. ^School of Geosciences, Monash University, PO Box 28E, Clayton Victoria 3800, Australia. "^Geoscience Australia, PO Box 378, Canberra, ACT 2601, Australia. School of Earth Sciences, University of Tasmania, Private Bag 79, Hobart, Tasmania 7001, Australia. Corresponding Authors email address: sjgall@unimelb.edu.au The warm greenhouse world of the Late Cretaceous created an ocean that was poorly stratified latitudinally and vertically. Periodically these oceans experienced globally significant events where oxygen minimum zones enveloped the continental margins. Evidence of the effect of one of these Ocean Anoxic Events (OAE's) is preserved in the southern high latitude strata of the offshore Otway Basin in southeast Australia. During the Late Cretaceous, thick succession of mudstonedominated deltaic to upper bathyal sediments (the Otway Delta) were deposited in an elongate inlet (ca. 500 km wide) between Antarctica and Australia located at least 70°S. The initial Turonian strata of this succession (the Waarre Formation) weie deposited in upper delta plain to delta front conditions. The overlying Flaxman Formation and basal Belfast Mudstone Formation preserve evidence of transgressive lower delta plain to prodelta conditions at inner to middle shelf depths. These Turonian units were subject to periodic dysoxia during deposition. The conditions that created dysoxia in the region might have been caused by intermittent freshwater input and deepening seas caused periods of thermohaline stratification and reduced bottom waters. The overlying Coniacian Santonian Belfast Mudstone Formation was deposited in prodelta to upper bathyal conditions at middle shelf to upper slope depths subject to periodic fluctuations in dysoxia with normal marine salinities. After a period when the oxygen minimum zone contracted, upward-increasing dysoxia in the Belfast Mudstone Formation herald the onset of the Coniacian to Santonian dysoxic conditions. This event in the Otway Basin correlates to OAE 3, the last Ocean Anoxic Event of the warm Cretaceous
before the onset of cooler conditions in the uppermost Cretaceous. Typically 0AE3 intervals are recorded in tropical latitudes, the strata in the Otway Basin preserves evidence of one of the most southerly oceanic dysoxic events in this period. Eventually, hyposaline conditions or higher sedimentation rates due to delta front progradation and shallowing in the Santonian caused the local extinction and dissolution of many of the calcareous benthic foraminiferal taxa of the Belfast Mudstone Formation
Low-enthalpy geothermal systems driven by convection in fault zones Klaus Gessner^^^, Heather S h e l d o n \ Klaus Regenauer-Lieb^ ^ Michael Kuhn"^, Christian Kosack^'^ ^Computational Geo science, CSIRO Exploration and Mining, Bentley, WA 6102 (kgessner@ cyllene. uwa. edu. au) Centre for Exploration Targeting, The University of Western Australia, Crawley WA 6009 School of Earth and Geographical Sciences, The University of Western Australia, Crawley WA 6009 GeoForschungsZentrum Potsdam, 14473 Potsdam, Germany ^ Christian Kosack, Applied Geophysics and Geothermal Energy, RWTH Aachen, 52056 Aachen, Germany Recent investigations in active geothermal systems in Europe have demonstrated that lowenthalpy geothermal systems (LEGS) associated with free thermal convection in faults may be prime targets for geothermal exploration. In comparison to Hot Dry Rock (HDR) systems, exploitation of LEGS requires less water, less cooling, and has a much lower risk of permeability destruction during production. Exploration for LEGS demands an understanding of the factors that control free thermal convection in the Earth's crust. Numerical simulations can be used to predict the occurrence, shape and size of convection cells once the properties and geometry of the system are known, and to explore the sensitivity of the system to variations in geometry and fluid/rock properties. Permeability is a key factor governing the occurrence and significance of free convection in the Earth's crust. For typical geothermal gradients and fluid properties, permeability must be above average in order for convection to take place. Fault zones and aquifers thus play a key role in determining patterns of free convection in the crust. Deep boreholes indicate that fault zones can be highly permeable at depths of 7 km or more, suggesting that convection may be more widespread than is often assumed. The shape, size and orientation of convection cells is determined primarily by the geometry of the
continued next page..
Australian Earth Sciences Convention 2008
108
ABSTRACTS alphabetically by surname of presenting author
system. For example, convection may take place in the plane of a permeable fault zone, rather than between fault zones, depending on the spacing of faults and the permeability of rock units between them. We present results from numerical simulations of free thermal convection in two and three dimensions. Our results suggest that free thermal convection in fault zones is a feasible process, and demonstrate the importance of considering the three-dimensional nature of convecting systems in order to predict the location of hot convective upwellings.
Taxonomy and Paleoenvironment of Lepidocyclina(Nephrolepidina) kirkuknesis new species (Foraminifera) from Late Oligocene (Baba Formation) in Kirkuk and Bai-Hassan Oil Fields, (Kirkuk, North Iraq) Imad Mahmood Ghafor^ Qahtan Ahmad Mohammad
^Dept. of Geology, College of Science, University of Sulaimani, (drimadgh @ yahoo, co, iik) ^Kirkuk Technical College, Kirkuk, Iraq, (qahtaniraqi @ yahoo, com) Lepidocyclina(Nephrolepidina) kirkuknesis new Foraminifera from the Late Oligocene of Baba Formation (Kirkuk and baiHassan Fields, North Iraq) is described and figured based on variation in (Ai, C and) parameters in agreement with the principles of nepionic acceleration as defined by Tan Sin Hock.The paleoenvironment of the Lepidocyclina(Nephrolepidina) kirkuknesis is included as shallow marine platform according to the lithological features and faunal association.
Biometric Analysis of Lepidocyclina (Nephrolepidina) from Baba and Azkand Formations (Oligocene-Miocene) in Kirkuk area, Iraq Imad Mahmood Ghafor^ Qahtan Ahmad Muhammed ^Department of Geology, College of Science, Sulaymanya University Kirkuk Technical College The investigation is based on a well exposed and subsurface sequences of bioclastic limestone in Kirkuk area. These sequences were deposited in a shallow open marine environment during Chattian to Aquitanian. Tests of larger foraminifera Lepidocyclina(Nephrolepidina) are abundant in the Australian Earth Sciences Convention 2008
lower and upper parts of the successions. Biometric investigations of the Megalospheric forms of Nephrolepidina assemblages from several sections in Kirkuk area included (Kirkuk well-19, Bai-Hassan well- 4, Khabaz well-3 and Qarah Chauq Dagh) led to recognize three morphometrically defined species by the combination of three parameters, the degree of embracement of the protoconch by the deuteroconch (Factor A), the numbers of accessory auxiliary chambers on the deuteroconch (Factor C), and (Factor a ) which expressed by the protoconch angle formed by the two hypothetical line from the center of protoconch throught the outer attachment points of the deuteroconch walls with protoconch
Using AEM imagery to map palaeo-strand lines in the Loxton Parilla Sands, Murray River corridor, Victoria David Gibson ^Cooperative Research Centre for Landscape, Environments and Mineral Exploration (CRC LEME), c/o Geoscience Australia, GPO Box 378, ACT2601, Australia (david.gibson@ga.gov.au) The Late Miocene to Pliocene Loxton Parilla Sands were deposited as nearshore shallow marine sands and shoreface dunes as relative sea level in the Murray Basin fell from a Late Miocene maximum. Small rises in relative sea level superimposed on the longer term fall are thought to have winnowed the seaward face of the dunes, leading to removal of fines, and concentration of heavy minerals. Variations within the Loxton Parilla Sands that are important for aquifer dynamics have been mapped from AEM and magnetic surveys, and DEMs along much of the Murray corridor between the Victorian/SA border and Gunbower Island. The general trend of the strandlines is evident on regional DEMs where they have not been eroded or buried. In addition, new magnetic imagery highlights the trends, due to concentrations of heavy minerals. The AEM data have been processed into 5 m thick conductivity slices parallel to the general surface of the youngest Murray floodplain scroll bars. These slices were used to map linear conductivity highs and lows parallel to the strandline orientations determined from the DEMs and magnetics. As well sorted sands have lower porosity and hence lower water content at saturation than muddy sediments, the conductivity lows are interpreted to represent sandier and hence more transmissive sediment, and the highs to represent more clay rich sediment. Hydraulically transmissive zones within the Loxton Parilla Sands provide pathways for saline water from the regional aquifer to enter the River Murray (gaining stream) or for fresh water from the
ABSTRACTS alphabetically by surname of presenting author
Murray to leak into the groundwater (losing stream). Knowledge of these more hydraulically transmissive sandy zones is vital for management of groundwater and vegetation health in the area.
Proterozoic crustal architecture and evolution in the Mount Isa region: new insights from seismic reflection profiling
Variability in landscape evolution rates, and the preservation of regolith
G.M. Gibson^ L.E.A. Jones\ L J . , Hutton^ B. Jupp^ D. Maidment\ R C . Murphy^ R J . Korsch\ R.D. Costelloe\ J. Holzschuh\ H.C. Tassell^ E. Saygin^ and D.L. Huston^
David Gibson' and John Wilford' ^Cooperative Research Centre for Landscape, Environments and Mineral Exploration (CRC LEME), c/o Geoscience Australia, GPO Box 378, ACT2601, Australia (david.gibson@ga.gov.au) There are many literature references to the age of landscapes, the rate at which they have developed, or the shape of palaeolandscapes. Most are based on ages of or time since burial of sediments, elapsed time since crystallisation of igneous flows and pyroclastics that form parts of the landscape, measurement of cosmogenic isotopes generated in the near surface environment, or the measurement of palaeotemperatures by geothermometers. These diverse methods of dating have various accuracies, and the inferred rates of deposition or denudation derived from these dates also may depend on assumptions (for example assumed geothermal gradient). However, derived estimates of landscape erosion rates are applicable only for the location of the sample. Further assumptions need to be made to extend the age or rate of development of a landscape away from the sample locations. Analysis of K-Ar basalt ages from eastern Australia shows that various parts of some catchments have eroded at differing rates over various spatial scales, suggesting changes in local relief variation and drainage geometry with time. In particular, some divide areas appear to have eroded very slowly over the last 50 My, whereas the associated valley floors have eroded more quickly, resulting in an increase in catchment relief with time. This situation leads to the preservation of thick weathering profiles (which form important salt stores) in upland areas and occurrence of fresh rock near valley floors. However, where divides are actively eroding, sediment may be trapped in valley floors, leading to minimal regolith preservation on divides, and thick sediment in the valley floors which have the potential to store large amounts of salt. In this case, catchment relief decreases with time.
^Geoscience Australia & Predictive Mineral Discovery CRC (Pmd'^CRC), Canberra (George.gibson@ ga.gov.au) Geological Survey of Queensland, Indooroopillyi Laurie. Button @ dme. qld.gov. au) ^Pmd'^CRC, Melbourne (bmurphy@unimelb.edu.au) Palaeoproterozoic-earliest Mesoproterozoic sequences deformed during 1620-1585 Ma orogenesis in the Mount Isa region preserve an earlier record of intracontinental rifting, synextensional magmatism, and low pressure/high temperature metamorphism linked to basin formation and normal faulting at upper crustal levels. Crustal thinning occurred nearly continuously from 1800 to 1640 Ma, resulting in three vertically stacked sedimentary basins (Leichhardt, Calvert and lowermost Isa superbasins) and a depositional environment which evolved from narrow continental rift to inferred passive continental margin. Seismic reflection profiles oriented at high angles to the Leichhardt and Calvert structural trends show that growth faults and half-graben geometries are widely preserved in the western succession whereas the eastern succession is dominated by basin inversion and an east-dipping thrust stack that developed above previously extended continental crust. A major crustal-penetrating structure dips west beneath this thrust stack and separates crust with stratigraphic affinities to the rest of Mount Isa from rocks with a different seismic character and crustal architecture. The latter appear to have more in common with highly extended crust beneath the Eromanga Basin to the east and may be allochthonous with respect to the rest of the Mount Isa Inlier. These rocks possibly represent a western extension of the neighbouring Georgetown block, which together with the PalaeoproterozoicMesoproterozoic sequences of Mount Isa, Broken Hill and eastern Gawler, may once have formed part of a single continental-scale rift system. Passive margin formation in the Mount Isa region was arrested by the onset of basin inversion at 1640 Ma, coincidental with the inferred docking of the Warumpi terrane against the southern margin of the north Australian craton. From 1640 - 1575 Ma sedimentation took place in a foreland basin (upper Isa superbasin) until terminated by a second phase of basin inversion associated with the Isa orogeny.
Australian Earth Sciences Convention 2008
109
110 ABSTRACTS alphabeticaiiy by surname o f presenting author
Crustal Budgets, Shifting Continents & the Search for Proterozoic Ores Dave Giles ^ ^Centre for Mineral Exploration Undercover, Discipline of Geology and Geophsics, School of Earth and Environmental Sciences, The University of Adelaide. (David. Giles @ adela ide. edu.au) In this talk I will discuss the relationship between long wavelength global tectonic (supercontinent?) cycles and the episodic distribution of ore deposits through time. I will focuss on the relationships between tectonic setting, chemical environment and preservation potential for a number of ore deposit styles common to the Proterozoic. A significant control on the episodic distribution of ore deposits through time is the tectonic setting in which certain types of ore deposit formed (eg. porphyry deposits in arcs, sedimenthosted deposits in rifts). Taken to their logical conclusion these associations suggest that there should be a global temporal relationship between maxima of certain ore deposits and the postulated global tectonic cycles that span the Proterozoic. Indeed, to a first order approximation this appears to be true. There are however additional factors that we should consider. The first of these is the changing chemical environment in the atmosphere and hydrosphere, which has had direct influence on the formation of mineral deposits in the near surface environment - notably in deposits hosted by sediments. The second, and perhaps most important of these factors is preservation. For example, porphyry systems have a low probability of preservation due both to erosion and the likelihood of long-term reworking or consumption of the convergent margin. As a general rule the preservation of convergent margin sequences should be a competition between rates of accretion and rates of erosion and consumption - which appear to be tipped in favour of accretion during periods of supercontinent assembly. Thus deposits associated with convergent margins correlate strongly in time with periods of supercontinent assembly - not necessarily because rates of subduction were greater but because newly accreted material was trapped by collision before it could be consumed.
The dregs of weathering: regolith mineralogy and chemistry Prof. Bob Gilkes^
^School of Earth and Geographical Sciences, The University of Western Australia Regolith has an image problem, as at first sight it seems boring. It is mostly featureless and Australian Earth Sdences Convention 2008
comes in only three colours reddish, whitish or greenish. No wonder that exploration geologists prefer outcrop or even gossans with recognisable features, yet regolith is actually diverse, versatile and capable of informing us of hidden mineralisation and complex palaeoprocesses. The memory of regolith is mostly provided by the clay minerals and sesquioxides that are major constituents. Clay minerals and sesquioxides have crystals that are nanometric, consequently surface area ranges from 1 0 - 200 mVg. Many geochemical reactions in regolith involve adsorption on to mineral surfaces, thus these minerals exert a major influence on the mobility of cations and anions. Surfaces of clay minerals and oxides are electrically charged and also contain sites where specific adsorption of ions occurs. Thus the mobility of Au, Cu, Zn, Ni etc in regolith is strongly influenced by the particular mineral surfaces exposed to regolith solution and also by the composition of the solution as pH, redox and other dissolved ions may gready affect speciation and surface reactions. Another characteristic of regolith microminerals is that the internal structure of crystals of clay minerals and sesquioxides is generally disordered, resulting in a high density of defects and of sites that can accommodate diverse cation substitutions. For example, goethite (aFeOOH) in regolith usually has some Fe^^^ replaced by Al^^and sometimes Cr^^, Ni^^and other metal ions are present. This enables goethite to "remember" the composition of the regolith solution from which it crystallised, even when conditions have subsequently changed due to water table, chmate, salinity and other events. Even kaolin is capable of accommodating low concentrations of foreign metal ions.
Application of mineral exploration mapping tools and concepts to groundwater resource evaluation. Bruce Gil\\ Jon Fawcett\ Don Cherry^ Tania Kennedy^. ^ Department of Primary (bruce. iiill@ dpi, vie, gov, au) ^ Ballarat University
Industries
Victoria
Considerable uncertainty remains about the sustainable groundwater yields of most aquifers in Australia. Especially during drought, when there is increased call upon the resource, regulatory authorities (and resource users) require as much certainty as possible as to the volume of groundwater that can be safely allocated. This study has been funded by the National Water Commission and the Victorian Water Trust over three years (from January 2008). The overall objective is to explore the potential of new tools and methods developed in the mineral exploration industry to improve the certainty of groundwater resource estimation of important aquifers through
ABSTRACTS alphabetically by surname of presenting author
production of better 3D delineation of aquifers. Some of the avenues to be explored in this 3 year research study include: • How to customise emerging technologies of 3D, GIS based lithological mapping and analysis for hydrogeological needs. • How to develop and make best use of complementary geo-referenced data sets within state and national geological data sets. • How to adapt suitable mining and oil industry tools for use in groundwater resource evaluation and sustainable yield estimation. • Development of more robust groundwater resource estimation methods similar to the level required for mining industry stock market reports. • Whether the improved delineation of aquifers in 3D provides better underpinnings for mathematical groundwater models. • Use of 3D visualisation products to assist managers and communities to better understand the resource. • The potential of the 3D data to enhance understanding of surface water - groundwater interactions, land-use change and climate change. This paper will report on the initial 6 months foundation work on the project. This will summarise the current world practices and their applications, as well as the initial development of compatible hydrogeological data sets for focus areas in Victoria. From this exposure at the AESC conference, the authors hope to tap into any insights people may have about the study.
Metallogenesis of the Koonenberry Belt, Northwestern New South Wales P.J. Gilmore^ J.E. Greenfield\ W.J. Reid^ and K.J. Mills^ ^Geological Survey of New South Wales, NSW Department of Primary Industries, PO Box 344, Hunter Region Mail Centre, 2310. (philgilmore @ dpi. nsw. gov.au) ^Geological Survey of New South Wales, NSW Department of Primary Industries, PO Box 696, Broken Hill, 2880. The Koonenberry Belt in northwestern New South Wales is an underexplored terrane that has been a focus of the Geological Survey of NSW through the Discovery 2000, Exploration NSW and the current New Frontiers initiatives. Analysis of new geological mapping, geochemistry, isotope data and geophysics, along with 3D modelling, have resulted in revised interpretations of the tectonic evolution of the Koonenberry Belt, with direct implications for the belt's metallogenesis and
exploration potential. Forming part of the Delamerian Orogen on the eastern margin of the Curnamona Craton, the Koonenberry Belt has undergone a complex tectonic history that has resulted in a diverse range of sedimentation and volcanism, with multiple phases of deformation. The Koonenberry Fault, the dominant structural feature of the belt, is a longlived deep crustal structure that has provided a conduit for fluid flow in association with other structures. Orthomagmatic Ni-Cu-PGE mineralisation is associated with an intracontinental rift related suite of alkali basalts. Besshi-style VMS Cu-ZnAg-Au deposits are interpreted to have formed in an extensional environment associated with spreading ridges in the middle Cambrian at the onset of westward subduction related to the Delamerian Orogeny. Orogenic Au related to deformation during the early Silurian Benambran Orogeny is hosted by turbidite sequences to the east of the Koonenberry Fault. Ag-Pb-Cu mineralisation associated with an epithermal event is interpreted to coincide with the opening of the late Silurian to early Devonian Mount Daubeny Basin. In addition to primary mineralisation, multiple deformation events have provided structural complexity and the potential for upgrading of mineralisation. Complex landscape evolution has resulted in alluvial related Au deposits in Cretaceous and Quaternary units. This work is published with the permission of the Deputy Director General, NSW Department of Primary Industries; Mineral Resources.
Mass wasting along the East Australian continental Slope. Kriton C. Glenn ^ Alix Post\ Ron Boyd^ and Jock Keene^ 'Geo science Australia Petroleum and Marine Division, GPOBox378, Canberra, ACT 2601 Australia. School of Environmental and Life Sciences, University of Newcastle. School of Geosciences, F09, The University of Sydney, NSW, 2006 Australia Geoscience Australia has undertaken an assessment of the High Risk Areas for future submarine slides and their tsunami genie potential. The results of a 15-day marine survey along the NSW continental slope adjacent to population centres and critical infrastructure provided a regional understanding of the morphology and the mass wasting history between Jervis Bay in the south to Forster in the north. The data sets from this survey, firmly indicate that significant areas of the NSW continental slope have been prone to sediment mass wasting over time. Critical factors for these wasting features include
continued next page..
Australian Earth Sciences Convention 2008
111
112 ABSTRACTS alphabetically by surname of presenting author
basement slope and overlying sediment thickness. Failures are observed as tension cracks, creep, faulting, debris flows and significant slides, eg Bulli (-20 km^). Shovel (7.97 km^), Birubi (2.31 km^) and Yacaaba (0.24 km^) slides. Dating of the slides is challenging as none of the cores penetrated the unfailed surface, consequenUy no exact failure dates can be established. The preliminary findings are based on 23200 km2 high resolution bathymetry, 3414 line kms of sub-bottom profiles, 11 gravity cores and 340 line kms of seismic. Based on the seismic data there are two distinct types of gravity slides on this margin. There are those related to the sediment bedding planes in the Cainozoic wedge and a second group that are related to the seaward face of volcanic highs. Future failures may also exhibit this relationship and feature packets of sediment unsupported by underlying buttress formations. Taking these factors into consideration and assessing the location of significant un-failed sediment accumulations, a preliminary prediction can be made about the location of high risk areas for future slides.
Milestones in the evolution of the atmosphere with reference to climate change Andrew Glikson^ ^ Australian National University - Research School Of Earth Sciences Life on Earth is critically dependent on the carbon, sulphur and oxygen cycles of the lithospherehydrosphere -atmosphere -biosphere system. An Archaean oxygen-poor greenhouse atmosphere developed through (1) accumulation of C02 and CH4 from Episodic injections of C02 volcanic activity, volatilized crust impacted by asteroids and comets, metarrorphic de-volatilization processes and release of methane from sediments, and (2) little C02 weathering-capture due to high temperatures of the hydrosphere (low C02 solubility) and little weathering-capture of C02 due to a low ratio of exposed continents b oceans. In the wake of the Sturtian glaciation enrichment in oxygen and appearance of multicellular eukaryotes heralded the onset of the Phanerozoic where greenhouse conditions were interrupted by periods of strong C02-sequestration through intensified capture of C02 by marine plants, onset of land plants and burial of carbonaceous shale and coal (late Ordovician. Carboniferous-Permian, late Jurassic, late TertiaryQuaternary). The progression from late Mesozoic and early Tertiary greenhouse conditions to late TertiaryQuaternary ice ages was related to the sequestration of C02 by rapid weathering of the emerging Alpine and Himalayan mountain chains. A number of peak warming and sea level rise events include the late Oligocene, mid-Miocene, mid-Pliocene and Pleistocene glacial terminations. The late TertiaryQuaternary ice ages were dominated by cyclic orbital forcing-triggered terminations which involved C02-
Australian Earth Sciences Convention 2008
feedback effects from warming seas and the biosphere and albedo flips due to ice sheet melting. Since ~1750AD human emission of -305 Gigatons of carbon, as compared to -750 GtC of the atmosphere. The emissions constitutes -12 percent of the terrestrial biosphere and -10 percent of the known global fossil fuel reserve of -4000 GtC, whose combustion would compare to the - 4600 GtC released to the atmosphere during the KT impact event 65.10^ years ago, with associated -65 percent mass extinction of species. Current growth rate of atmospheric greenhouse gases and global mean temperatures exceed those of Pleistocene glacial terminations by one to two orders of magnitude. The relations between temperatures and sea levels (SL) for the last few million year project future SL rises toward time averaged values of at least 5 meters per r c . The instability of ice ^eets suggested by the Dansgaard-Oeschger glacial cycles during 50-20 kyr, observed ice melt lag effects of glacial terminations, spring ice collapse dynamics and the doubling perdecade of Greenland and west Antarctic ice melt, suggest that the IPCC-2007-projected SL rises for the 21st century may be exceeded.
Direct Field Evidence for Archaean and Early Proterozoic Eros-scale Asteroid Impacts and Major Geodynamic Consequences, Kaapvaal and Pilbara Cratons. Dr Andrew Glickson^
^Research School Of Earth Science, Australian National University The role of asteroid and comet impacts as triggers of mande-crust processes poses one of the fundamental questions in Earth science. I present direct field evidence for close associations between impact ejecta/fallout units, major unconformities and lithostratigraphic boundaries in Archaean and early Proterozoic terrains, including abrupt changes in the composition of volcanic and sedimentary assemblages across strati graphic impact boundaries, with implications for the nature and composition of their provenance terrains. As originally observed by D.R. Lowe and G.R. Byerly, in the Barberton Greenstone Belt, eastern Kaapvaal Craton, South Africa, 3.26-3.24 Ga asteroid mega-impact units are closely associated with the abrupt break between an underlying simatic mafic-ultramafic volcanic crust and an overlying association of turbidites, banded iron formations, felsic tuff and conglomerates of continental affinities. Contemporaneous stratigraphic relationships are identified in the Pilbara Craton, Western Australia. Evidence for enrichment of seawater in ferrous iron in the wake of major asteroid impacts reflects emergence of new source terrains, likely dominated by mafic compositions, attributed to impact-triggered oceanic volcanic activity. Relationships between Impact and volcanic activity are supported by the onset of major mafic dyke systems associated with -2.48 Ga and possibly the 2.56 Ga mega-impact events.
ABSTRACTS alphabetically by surname of presenting author
The Merensky Reef of the Bushveld Complex (South Africa): a X-ray computed tomography, microstructural, geochemical and mineralogical study Belinda Godel^*. Wolfgang D. Maier^ and Sarah-Jane Barnes^
' Centre for Exploration Targeting, UWA, Crawley, 6009, Australia (bgodel@cylleneMwa.edu.au, wdmaier@cyllene. uwa. edu. au) ^ Sciences de la Terre, UQAC, Chicoutimi, 07H 2B1, Canada (sjbarnes@uqac.ca) The Merensky Reef (MR) of the Bushveld Complex at the Rustenburg Platinum Mine consists, from bottom to top of: anorthosite; a lower layer of chromitite (0.5 to 1 cm); a coarse-grained melanorite; a second layer of chromitite of (~1 cm); and finally a melanorite. We carried out a detailed analysis of a slab of MR, including the determination and quantification of the base-metal sulfide (BMS) distribution in 3-D by X-ray Computed Tomography, the analyses of platinum-group elements (PGE) in both the BMS, chromites and silicates (by laser-ablafion ICP-MS) and the whole rocks, and the study of platinumgroup minerals. This was done to: (i) establish the phases concentrating the PGE, (ii) evaluate the role of the sulfide liquid in the PGE collection, and (iii) evaluate the processes which may have triggered the formation of the Merensky Reef. In the silicate rocks (anorthosite and melanorites), the BMS are located along verfical networks that terminate in the underlying chromites. The BMS are concentrated just above each chromitite layer. Geochemical modelling indicates that the PGE present either in BMS or as PGM were collected by an immiscible sulfide liquid which percolated downward along dilatancies formed between silicate grains as a result of extension in layer plane of the layer during compacfion. In contrast, in the chromitite layers the BMS occur as sulfide droplets. Dihedral angle measurements indicate that sufide meh percolation in these layers is negligible. In these layers, the collecfion of the PGE may have occured in two steps: some PGM (mainly laurite and Pt-rich phases) crystallised from the magma during chromite crystallization and before sulfide saturation; subsequently an immiscible sulfide liquid formed, collected the remaining PGE, and percolated downward until it reached the chromitites.
Ancient analogues for CO2 sequestration in coal measures, Gunnedah and Bowen Basins, Australia Suzanne D. Golding. 1. Tongue Uysal, Joan S. Esterle
C02CRC and Earth Sciences, University of Queensland, QLD 4072, Australia (s. golding 1 @ uq. edu. au) Coal bed methane (CBM) fields in sedimentary basins are possible repositories for anthropogenic CO2 with the added economic benefit of enhanced recovery of CBM. This reflects the higher adsorption capacity of coal for CO2 relative to CH4. CO2 is stored in coal as adsorbed molecules on micropore surfaces, but will also dissolve in formation water (solution trapping) and react with Ca, Mg and Fe-bearing minerals in the coal. Dissolution and precipitation reactions will buffer the pH decrease associated with injection of CO2 and may result in the formation of carbonates (mineral trapping). The rates and consequences of fluidmineral interaction in natural systems are known to vary from those determined in the laboratory. It is essential, therefore, to use observations from natural analogues to understand the long term consequences of the injection and storage of CO2 in coal measures. In the current study we have investigated mineral paragenesis and the physico-chemical conditions under which diagenesis occurred in CO2rich and C02-poor coal seams and adjacent strata of the Gunnedah and Bowen Basins. Intense carbonate veining and cleat mineralisation in the Gunnedah Basin is associated with local Cretaceous - Tertiary intrusions, whereas widespread carbonate veining and cementation in the Bowen Basin is interpreted as products of basin-wide CO2 rich meteoric hydrothermal fluids. Dawsonite is absent in the Bowen Basin (except Denison Trough), but it is common along cleats and fractures in the Gunnedah Basin indicadng elevated CO2 fugacity and alkalinity in the geochemically more evolved environment at the latest stage of the fluid flow process. The formation of dawsonite is attributed to low permeability of the system and high sorption capacity of CO2 on coal that facihtated increasing CO2 accumulation in the coal seams with insignificant leakage. Based on stable and radiogenic isotope data, possible CO2 sources for the carbonates include 1) thermal degradation of organic matter (calcite and ankerite), 2) bacterial methanogenesis (siderite), and 3) magmatic gas and/or original marine carbonate (dawsonite and some calciteankerite).
Australian Earth Sciences Convention 2008
113
114 ABSTRACTS aiphabeticaiiy by surname of presenting author
Isotopic Evidence for Redox Heterogeneity in the Late Archean and Early Paleoproterozoic Hamersley Basin, Western Australia Suzanne D. Golding^ Michaela A. Partridge^ Kim A. Baublys\ Elisa Young^ ^Earth Sciences, University of Queensland, QLD 4072, Australia (m.partridge@uq.edu.au) The multiple sulfur isotope record from various pyrite morphologies in Western Australia's Hamersley Basin suggests that the redox state of the ocean fluctuated through the late Archean from at least 2.6 Ga and potentially constrains the origin and relative impact of various microbial metabolisms during the transition from an anoxic to oxic atmosphere and hydrosphere. In late Archean deeper water environments, fine grained pyrite with positive S^'^S and A^^S formed under anoxic conditions, possibly via microbial utilisation of atmospherically derived elemental sulfur (Farquhar et aL, 2007, Nature, v. 449, p. 706). On the other hand, fine grained pyrite with near zero and less positive A^'^S may have formed in somewhat more oxic conditions by multi-stage sulfur cycling beneath the sediment-water interface (Kaufman et al., 2007, Science, v. 317, p. 1900), whereas pyrite nodules with negative A^^S formed via microbial sulfate reduction during early stage diagenesis. Shallower water late Archean pyrite also exhibits both negative and positive A^^S in different morphologies; however, their diverse 5 S compositions imply the activity of sulfate reducing microbes in a more oxic depositional environment than that of the deeper water Archean sediments. The early Paleoproterozoic marks a transition toward modern sulfur isotope values, with less isotopic diversity across pyrite morphologies; however, sulfur isotopes do still vary with depositional environment. A restricted range of 8 S values in the pyrite from deeper water environments reflects a partially hydrothermal origin, while highly variable and near zero A^^S values in shallow water pyrite indicate formation via microbial sulfate reduction in a somewhat oxidised environment where sulfate was not limiting. An important exception to this is the strongly negative A^^S recorded in a carbonate facies iron formation. This may suggest that deeper water hydrothermal environments remained anoxic while shallower water environments became more oxidised by the early Paleoproterozoic.
^ Geoscience Australia, PO Box 378 Canberra ACT 2601, Australia (bruce.goleby@ga.gov.au) Geoscience Australia continues to acquire high quality deep seismic reflection data as part of its ongoing program of providing datasets and information for understanding the structure and evolution of the Australian Continent. The majority of the Australia continent is covered at least one seismic section providing glimpses of the structure of the crust. Deep seismic reflection surveys undertaken in the last 3 years include the 2005 Tanami Survey, the 2005 Thompson-Lachlan Survey, the 2006 Victorian Survey, the 2006 Mt Isa Survey and the 2007 Isa-Georgetown-Charters Towers Survey. These surveys cross a range of geological provinces from different tectonic environments covering a range of time periods. The seismic results indicate a gross similarity in seismic character between similar geological provinces which suggests a similar evolution which in turn can be used to develop crustal scale tectonic models. The understanding of seismic characteristics within the upper crust continues to be an important component in interpretation of data from mineral provinces as well as petroleum basins, as the reflection seismic method is one of a few methods that image structures to depth within a region. These seismic surveys have provided exciting images of the crustal architecture along 2D transects which, when used together, provide depth constraints for 3D geological framework models. Data from these surveys are a fundamental component of understanding tectonic evolution, as well as providing important information on possible mineral systems associated with the tectonics. The seismic data have also shown their worth in constraining possible mineral and petroleum systems that operated in an area as well as providing data that allows explorers to be more targeted in assessing the petroleum and mineral potential of an area. Results from several of the above seismic surveys will be presented to illustrate characteristics of the Australian Crust from Seismic Reflection Profiling
Early to Middle Triassic stratigraphy of the offshore eastern Bonaparte Basin and Londonderry High, northern Australia John D. Gorter^
Characteristics of the Australian Crust from Seismic Reflection Profiling
^ Eni Australia Limited, 40 Kings Park Road, West Perth, Western Australia 6005 (john.gorter@eniaustralia.com.au)
Bruce Goleby^ Jenny Maher\ Ross Costelloe^ Tanya Fomin\ Josef Holzschuh^ Leonie Jones^ Aki Nakamura^ Erdinc Saygin\ Hugh Tassell\
The last substantial stratigraphic review of the Triassic of the offshore Northern Bonaparte Basin was in the early 1990s. Since then, numerous petroleum exploration wells and extensive seismic survevs have led to a better understanding of the
Australian Earth Sciences Convention 2008
ABSTRACTS 115 alphabetically by surname of presenting author
distribution of siliciclastic reservoir and seal facies in the region. Widespread reservoir facies are associated with erosional sequence boundaries, and both the lowstand sandstones and thin carbonatebearing flooding events can be correlated with eustatic events recognised in Tethys and elsewhere on the North West Shelf. The succession now recognised is (in ascending order) Penguin Formation (top Permian), Kinmore Group (containing Mairmull, Ascalon, and Fishburn Formations and Mt Goodwin Sub-group), Sahul Group (containing Osprey Formation and Anjo Sandstone Member, Crane Formation and Halcyon Limestone and Whimbrel Sandstone members, and Snowmass Sandstone), and Troughton Group (containing Cape Londonderry and Malita Formations). Widespread lowstand sandstones of reservoir quality are present in the middle of the Mt Goodwin Sub-group (Ascalon Formation), the Anjo and Whimbrel Sandstone Members and the Snowmass Sandstone. The Ascalon Sandstone is best developed in the south, and contains gas in several localities (e.g. Blacktip-1, Ascalon-1 A). The base of the Osprey Sandstone Member is a sequence boundary equated with the An2 lowstand in Tethys. The sandstones contain thin oil sands at Dillon Shoals-1 and poor gas shows at Osprey-1. The shalier Osprey Formation is progressively truncated southwards by the base Crane Sandstone Member unconformity, which is probably equivalent to the An3 lowstand in Tethys. The Snowmass Sandstone lies on a regional unconformity above progressively older Triassic strata southwards. This could be a tectonic sequence boundary with uplift to the south on the Londonderry High, or reflect the An4 (or Car3) lowstand in Tethys. The maximum marine flooding is in the Halcyon Limestone Member with ooids, shelly fossils and dolomite in cuttings, and equates with the Tethyan highstand between the An3 and An4 lowstands.
Revised stratigraphy of the Triassic (Induan to Carnian) in the northern Perth, Carnarvon and offshore Canning basins. John D. Gorter^ Robert S. Nicoll^ Roger M. Hocking^ and Andrea Caudullo^ ^ Eni Australia Limited, 40 Kings Park Road, West Perth, Western Australia 6005 (john.gorter@eniaustralia.com.au) (andrea.caudullo@eniaustralia.com.au) Earth and Marine Sciences, Australian National University, Canberra ACT, 0200, Australia (bnicoll@goldweb. com.au) The Induan to Carnian (Triassic) stratigraphy of the northern Perth, Carnarvon and offshore Canning basins is examined using timelines based
on sequence stratigraphic principles complemented by palynological and conodont biostratigraphy supported by published carbon isotopic measurements. Wireline log patterns supplemented by seismic profiles are used to develop the stratigraphic correlations. The Kockatea Shale facies is characterised by radioactive shales and carries the K. saeptatus Oppel Zone palynomorphs, and can be correlated from the northern Perth Basin northwards to the offshore Canning Basin. The Kockatea Shale is unconformable on latest Permian strata or basement. The correlations are supported by conodont biostratigraphy (e.g. Cunaloo Limestone Member). In the northern Perth Basin the strata overlying the Kockatea Shale are coarser grained non-marine sandstones, whereas in the Carnarvon Basin several wells show a highly erratic radioactive unit (with zircon and monazite), here called the Candace Member, unconformably overlying the Kockatea Shale facies. Unconformable on this radioactive unit is the conodont-bearing Sholl Limestone Member, the basal unit of the Locker Shale (with the T. playfordii Oppel Zone palynomorphs). The limestone is absent in some areas because of erosion by deep canyons within the Locker Shale. The Locker Shale, a less radioactive shallow marine facies than the Kockatea Shale, is unconformable below the Mungaroo Formation, a series of generally non-marine siliciclastic and coalbearing cycles that contains proven reservoirs for hydrocarbons in the Carnarvon Basin. The exact boundary conditions of these two formations are unclear but there appears to be a change upward from the T. playfordii Oppel Zone to the S. quadrifidus Oppel zone at this level. However, a thick carbonate unit, the Cossigny Limestone Member, is widespread in the lower part of the Mungaroo Formation in the northern Carnarvon and Canning basins. This was laid down in a marine environment, possibly coincidental with a major marine flooding also seen in the in the Bonaparte Basin and equated with the Tethyan highstand between the An3 and An4 lowstands.
Gold lode deposits in Orogenic Belts of Russian Segment of the Pacific Rim Nikolay A. Goryachev^ 'North East Interdisciplinary Scientific Research Institute of Far East Branch of the Russian Academy of Sciences, Magadan, Russia, goryachev@neisri.ru The territory of Russian Far East consist of different Paleozoic, Mesozoic and Cenozoic orogenic belts. This belts are marked of the zone of interaction between Pacific oceanic plates and North Asia craton. They are formed in two different kinematic conditions - (1) frontal collision (thrust style) and (2) slip collision (strike-slip or transform margin style) (Geodynamics..., 2006). All this continued next page.. Australian Earth Sciences Convention 2008
116 ABSTRACTS alphabetically by surname of presenting author
orogenic belts are hosted of different orogenic gold deposits. This deposits can be combined into the Late Mesozoic (Northern, Yana-Kolyma, MongoloOkhotsk, Stanovoy, Sikhote-Alin) and Cenozoic (Koryak, Sakhalin-Hokkaido) gold belts. Few gold lodes are located within different fragments of Paleozoic belts (Omolon, Khanka terranes). We have distinguished three different types of the orogenic gold deposits: (1) gold-bearing sulfide disseminated within sedimentary rocks (Degdekan); (2) mesothermal Au-quartz veins within sedimentary rocks (Tokur, Svetloye, Utin, Karalveem etc.) and granitoid-hosted and (3) granitoid-related (Chistoye, Askold etc.). They formed in Paleozoic (Noddy Silurian), Mesozoic (Natalka, Utin, Chistoye - Late Jurassic - Early Cretaceous and Nezhdaninskoye, Shkol'noye, Glukhoye, Oemku, Askold, Krinichnoye - Early-Middle Cretaceous) and Cenozoic (Nutekin, Rukosuevskoye - Eocene) time. Largest orogenic gold deposits of Russian Far East (Natalka, Nezhdaninskoye) combined of two types disseminated and veined. The epithermal Au-Ag deposits (Kubaka - Carboniferrous, Jul'etta - Early Cretaceous, Kupol, Karamken - Late Cretaceous, Aginskoye - Quarter, etc.) are post- or pre-orogenic and are typically subduction related (Geodynamics..., 2006). Mesothermal Au-quartz veins are predominated for frontal collision setting whereas granitoid-related type are predominated for slip collision setting. According to geological and mineralogical-geochemical data orogenic gold deposits of Russian segment of the Pacific Rim have been formed as result of orogenic plutonicmetamorphic processes (granite-metamorphic dome formation).
Metamorphic evolution of the Eastern Goldfields Superterrane B. Goscombe^ R.S. Blewett^, K. Czamota^ ^ prnd^'CRC, c/o Integrated Terrane Analysis, 18 Cambridge Rd. Aldgate SA 5154, Australia (ben.goscombe@adelaide. edu. au) ^ pmd'^CRC, c/o Geoscience Australia GPO Box 378, Canberra ACT2601 Australia. A metamorphic database covering the entire eastern Yilgam Craton has been compiled from pre existing mapping, 14,500 sites with qualitative metamorphic information, and 470 key sites with detailed quantitative metamorphic data including P, T, average thermal gradient and P-T paths. The derived temporal and spatial patterns contrast with previous tectonic models and invariant crustal depth with the single prograde metamorphic event of the long-standing metamorphic paradigm. In particular, there are large variations in peak metamorphic crustal depths (12.3 to 30.5 km), and five metamorphic events can now be recognised. • Ma: very localised, low-P granulite of high average thermal gradient (>50''C/km). Australian Earth Sciences Convention 2008
•
M l : high-P (8.7kb), low average thermal gradient (=20'C/km) assemblages localised to major shear zones with clockwise isothermal decompression P-T paths. • M2: regional matrix parageneses with T ranging 300-550^C across greenstone behs and elevated average thermal gradients of 3040°C/km throughout. Tight clockwise paths evolved through maximum prograde pressures of 6 kb and peak metamorphic pressures of 3.5-5.0 kb. • M3a: an extension related thermal pulse localised on the Ockerburry Fault and postvolcanic late basins. Anticlockwise paths to peak conditions of 500-580^C and 4.0 kb, define moderately high average thermal gradients of 40-50^C/km. • M3b: multiple localised hydrothermal alteration events during a period of exhumation from 4 kb to 1 kb. Metamorphic patterns during each event have been temporally and spatially integrated with the new deformation framework (Blewett & Czarnota, 2007, GA Record 2007/15) by a process of metamorphic domain analysis and using metamorphic field gradients.
Ice-rafting in the Mid-Ediacaran (-580 Ma) Adelaide Geosyncline and Officer Basin, South Australia Victor A. Gostin. David M. McKirdy, Lynn J. Webster and George E. Williams Discipline of Geology and Geophysics, School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia (E-mail: victor.gostin@:adelaide.edu.auj The Late Neoproterozoic Bunyeroo Formation is a thick unit of mostly red, laminated mudstone that occurs widely in the Adelaide Geosyncline. Isolated pebbles of siltstone and quartzite, clusters of quartz granules, rare rectangular patches of poorly-sorted coarse-grained sandstone up to - 1 7 0 cm^ in area, and small ovoid pellets of poorly sorted quartz silt occur in laminated mudstone - 8 0 m above the base of the formation. Similar small pellets have been found in red laminated mudstone of the correlative Dey Dey Mudstone in the eastern Officer Basin. The anomalously coarse-grained deposits in the Bunyeroo Formation are interpreted as dropstones, dumps and frozen aggregates, respectively, and the siltstone pellets in the Bunyeroo Formation and Dey Dey Mudstone as till pellets, all dispersed by floating ice. Ice-rafted material in the Bunyeroo Formation occurs <10 m stratigraphically below and above a volcaniclastic ejecta horizon related to the ~90 km diameter Acraman impact structure in the Mesoproterozoic Gawler Range Volcanics -300 km to the west (WiUiams & Gostin 2005, AJES v.52: 607-620). In the lower Dey Dey Mudstone till pellets
ABSTRACTS alphabetically by surname of presenting author
occur 11-68 m below the ejecta horizon in Munta-1 and 4.4 m below the ejecta horizon in Murnaroo-1. Hence a glacial climate prevailed at the time of the Acraman impact. Mid-Ediacaran ice-rafting in South Australia is dated at about 580 Ma and therefore appears coeval with the Gaskiers glaciation in Newfoundland and identified elsewhere in Australia and in USA, China, Norway, Scotland and Brazil. Following glaciation and a major bolide impact, the Ediacaran succession hosts a prominent negative carbon isotopic excursion, diversification of planktonic microfossils, and unusual biomarker signatures (McKirdy et al 2006, Org. Geochem. v.37: 189-207), followed by the rise of the Ediacara biota. This suggests that together the impact and glaciation may have catalysed the subsequent dramatic Ediacaran evolution.
Elastic Behaviour of Earth's Lower Mantle Solids Under High Compression S.C. Goval^ Seema Gupta^ S K Pathak^ ^Department of Applied Sciences, FET, R.B.S.College, Bichpuri, Agra ^Department of Physics, Agra College, Agra ^Department of Physics, St Johns College,Agra The extreme compression value of the pressure derivative of bulk modulus i.e. K ^ has been treated as an adjustable parameter in recent studies on high pressure equation of state (EOS) for solids. The present study presents the elastic behaviour of lower mantle metals i.e. Iron, Aluminium and Copper under high compression with the help of Birch- Murnaghan,Bre- Stacey, Shanker, Bom, Vinet, Bardeen, Ullaman, Tait, Equation of State. Further these EOS have been critically examined by evaluating the values of pressure derivative of bulk modulus at infinite pressure . The value of this parameter is found out to be greater than 5/3 by some EOS in case of some earth' lower mantle solids . Such result is in good agreement with the seismic Study of these metals.
Understanding the landscapes of the Perth Region
Colony, later to become Perth, on the north bank of the Swan River, describing it as ideal for establishing a permanent settlement. In particular, he recognized the defensive prospects of Mount Eliza, situated as it is where the Swan River narrows, which would make defending the fledgling colony from gunships easy, with just a few cannon. The landscape is intimately related to the nature of the underlying geology and many striking landforms and geological sections in the Perth Region provide insights into the geological history of the region, and to the development of the landscape as we see it today. The landforms of the coastal areas record the fluctuating sea level and are the result of the glaciations of the Pleistocene; exposed river-banks and subtle landforms of the Swan Valley reveal the history of the migrating river systems of the past; sedimentary rocks of marine origin at the foot of the Darling Scarp are evidence for an ancient shoreline, when the ocean covered all of what is now the Swan Coastal Plain; and quarries on the Darling Plateau reveal the complex history of the Yilgarn Craton, where metamorphic belts were intruded by large volumes of granitic rocks, and then eroded and deeply and intensely weathered over millions of years. The landscape and geology will continue to affect the development of the Perth Region, understanding how geological processes in the past have shaped the landscape will help us understand how similar processes may change our future. For example, understanding the effects of past sea-level changes will help us understand the possible effects of sea-level changes predicted for the coming century as a result of climate change.
The Top Down paradigm - do plants control groundwater and weathering in semi-arid Australia? David J Gray^ Adam M. Lillicrap^ ^ CSIRO Exploration and Mining, Private Bag 5, Wembley, Western Australia, 6913, Australia (david.gray @ csiro.au) ^ Centre for Ecohydrology. Department of Agriculture and Food Western Australia / University of Western Australia, 444 Albany Highway Albany Western Australia 6330 Australia (alillicrap @ agric, wa. gov. au)
Bob Gozzard^ ^Geological Survey of Western 100 Plain Street, East Perth (bob. gozzard@ doir. wa. gov. au)
Australia, WA 6004
From the stability of the Darling Plateau to the dynamic coastal environments, the landscapes of the Perth Region have influenced the development of Perth from earliest colonial times. In 1829 Captain James StirUng established the Swan River
Across arid and semi-arid southern Australia there are sharp spatial differentiations between differing botanical, soil and groundwater zones, seemingly independent of geological variation. Based on our observations and extensive process modelling, we now contend that all these factors are highly integrated, and that these effects are also controlling any ongoing deep weathering within the Yilgarn Craton of Western Australia At approximately 30°S, the Menzies line, continued next page..
117
118 ABSTRACTS alphabetlcaify by surname of presenting author
represents a biogeographic boundary based on climate with subsequent influence on botany and soils. Hardpan soils and Acacia species are dominant to the north where the climate consists mainly of sporadic summer rainfall. Carbonate soils and Eucalyptus communities occur to the south where the climate is winter rainfall dominated. Southern groundwaters are highly saline, and acid in the upper 20 m. Previously this acidity was hypothesized to be due to "ferrolysis" (i.e., iron oxidation/hydrolysis) with Fe presumably released during weathering. However, we demonstrate that such a model is inconsistent with available data. Instead, we postulate that certain Eucalyptus species are controlling water budgets and soil chemistry so as to force calcite precipitation in the top 1 metre, with "potential" acidity (as Fe or organic intermediates) percolating deeper into the soil profile. This sub-surface water is concentrated by evapotranspiration processes, and rendered acid by oxidation, resulting in recharge of acid (pH 3-4) / saline (3-5% salinity) groundwater to the water table. In the upper oxidized regolith, this highly corrosive groundwater causes metal depletion and mobilization, and represents an environmental concern in agricultural areas where water-tables have risen following clearing. When this groundwater percolates into lower reduced regolith, dissolution of Fe-smectites and other minerals buffers pH back to 6.5, with release of significant dissolved Fe. The presence of this Fe-rich, saline, groundwater at the weathering front stabilizses most rock minerals, virtually stopping weathering. In contrast, north of the Menzies VmQ, Acacia is the dominant tree. Infiltration of rainwater is concentrated around the roots zones of plants on the valley floors. The hydrophobic soils resuh in the intermittent high-intensity rainfall, running off into valley floors where infiltration occurs in macropores around the root zones of vegetation - with little subsoil salinization as observed to the south. Upper soils are slightly acid, though the underlying hardpan suggests alkaline sub-soil - an opposite effect to that in southern areas. Groundwaters are fresh and neutral to alkaline (18% > pH 8), with low dissolved metals and little difference from shallow to deep regolith. Northern areas contain very high dissolved nitrate, presumably as a "leakage" from nitrogen fixation within Acacia root nodules. The presence of this potent oxidant, and lower salinity will lead to higher weathering rates than in the southern areas. As discussed above, we postulate that control over present soils and regolith is dominantly a complex feed-back between geology, soils, climate and vegetation, leading to relatively stabilized botanical differentiation. These effects move down through the regolith, leading to a "top-down" effect, swamping what might be considered "bottom-up" geological controls on these systems. Similar phenomena may be common in arid terrains of low relief elsewhere in the world. Australian Earth Sciences Convention 2008
The TasExplore Initiative and more: Updating the 3-D geological model of Tasmania Geoffrey R Green Mineral Resources Tasmania, PO Box 56, Rosny Park TAS 7018. Email: ggreen @mrt. tas.gov.au Tasmania was the first jurisdiction in the world to complete a 3-D geological model of an entire State. This 2004 model has highlighted gaps between modelled geology, using new geophysical data, and the older generation of 1:63,360 geological maps in central northern Tasmania. The model was deficient due to lack of detail in north-east Tasmania where there was little modem airborne geophysical coverage. The TasExplore Initiative is a four year project started in October 2006 and designed to stimulate mineral exploration through new geoscientific information and promotion: -
-
200 metre spaced aeromagnetic and radiometric data over NE Tasmania and the Furneaux Group; Infill gravity data over northern Tasmania; Geological mapping of selected areas of central northern Tasmania being updated published at 1:25,000 scale; Remapping of NE Tasmania and King Island for publication at 1:25,000 scale; Interpretations of the new geophysical data over NE Tasmania;
Metallogenic investigations of the Arthur Lineament, starting with the Savage River magnetite deposit; and - Updating of the 2004 3-D model to occur towards the end of the project. The recent mapping in the Central North of Tasmania has enabled better correlafion of the Mount Read Volcanics in the region with western Tasmania and specifically traced the key contact between the Tyndall Group and older units in this area. The geophysical interpretation of NE Tasmania has identified clusters of gold deposits associated with residual gravity highs and reduced magnetic response. Petrographic invesfigation suggests that the Savage River magnetite deposit is a high temperature skarn deposit of lOCG affinity (Bottrill and Taheri, this volume). Aeromagnetic data at 800 m line spacing and 25 km E-W spaced reflection seismic data is presently being acquired in selected areas of Bass Strait and along western Tasmania under a co-funded project with Geoscience Australia. This will provide information to extend the 3-D model northward, enabling sound correlation of key sequences in Tasmania and Victoria, as well as a better understanding of the formation of the Bass Basin.
ABSTRACTS alphabetically b y surname of presenting author
New South Wales, New Frontiers, New Opportunities. John Greenfield\ John Watkins^ , Richard Glen Bob Musgrave\ Gary Burton\ Nancy Vickery , Yvette Poudjom Djomani \ Phil Gilmore^ Geological Survey of NSW, PO Box 344 Hunter Regional Mail Centre NSW 2310 (John, watkins @ dpi. nsw. gov. au) The New South Wales Government has now completed the final year of its $8 million New Frontiers initiative (NFI), a program that has been
focused specifically on areas which are both under cover and under-explored. Building on the successes of Exploration NSW, NFI has paid particular attention to two frontier areas in the state's northwest and southwestern regions - the Thomson Orogen and extensions of the Stawell and Bendigo zones. The Thomson Orogen program has included the acquisition of deep crustal seismic reflection, high resolution magnetics, radiometrics and gravity, regolith studies, geochemistry, geochronology and drilling. The new data indicate that the Thomson Orogen may be an analogue of the Lachlan Orogen and contain an oceanic arc similar to the Ordovician Macquarie Arc that hosts the large porphyry systems such as Cadia, North Parkes and Cowal. Although most of the Thomson Orogen is under cover, basement is estimated to be less than 300 metres from surface in about 30 per cent of the area. Seismic data acquired in collaboration with PmdCRC, Geoscience Australia and ANSIR imaged the faulted boundary between the Thomson Orogen and the Lachlan Orogen. The Stawell-Bendigo program has also included the acquisition of high resolution magnetic and gravity data. The new data clearly shows extensions of the Stawell and Bendigo zones from Victoria into southern NSW. ModelUng of this data indicates that potential for structurally controlled gold deposits (similar to the Stawell and Magdala deposits) in the Stawell Zone extension north of Mildura is high. This abstract is published with the permission of the Deputy Director General Minerals, New South Wales Department of Primary Industries.
Structure and hydrothermal alteration associated with the Dahongshan iron oxide - copper (gold) deposit, SW China. Matthew Greentree^ Zheng Xian Li^, Mark Barley^
^Tectonics Special Research Centre, University of Western Australia (mgreentree@srk.com.au) ^Department of Applied Geology, Curtin University z.li@curtin.edu.au 3Centre for Exploration Targeting, University of Western Australia (mbarley@segs.uwa.edu.au)
The Dahongshan iron oxide - copper (gold) deposit is located in Yunnan Province, Southwest China. Mineralisation is hosted within the Dahongshan Group, a Paleoproterozoic (ca. 1675 + 8 Ma) metavolcano-sedimentary sequence (Greentree, 2007 unpubl. PhD thesis). Iron oxide - copper minerahsation is located on a major NW-striking fault zone. Within this high-strain zone the rocks are strongly foliated and tightly folded, with the foliation progressively steepening towards the west. Iron oxide mineralisation mostly occurs as magnetite or hematite. Most of the iron mineralisation is hosted by metavolcanic rock units proximal to major fault zones, and is typically conformable to the SI fabric. Within these rock units numerous individual magnetite lenses are identified, each up to 30 m in thickness and up to 1200 m in length .The texture and style of the magnetite mineralisation varies throughout the ore body, as do the iron grades, with the highest being obtained from the massive ores containing between 2 5 - 4 9 wt. %Fe. Copper mineralisation at Dahongshan occurs as stratabound, vein and disseminated massive sulphide mineralisation. A large portion of the copper minerahsation occurs within a zone of lowgrade (< 0.5 % Cu) disseminated minerahsation. Copper rich ore minerals include chalcopyrite, bornite and pyrite. Most of the copper ores also contain low-grade disseminated magnetite mineralisation (< 5%). Higher copper grades ('>0.8% Cu) occur within the biotite - chloritic schist and marble as discrete massive sulphide zones and as carbonate - sulphide veins. Mineralisation at Dahongshan has a broad halo of sodic and potassic alteration assemblages. Sodic alteration was the most significant during the iron oxide and copper minerahsation. Potassic alteration is a distal alteration phase and is closely associated with pyrite, sphalerite and gold mineralisation. Previous studies have suggested the Dahongshan deposit represents a VHMS style deposit. However, the structural controls, mineralogy of ores and hydrothermal alteration styles are more consistent with that of an lOCG style of mineralisation. continued next page.. Australian Earth Sciences Convention 2008
119
120
ABSTRACTS alphabetlcaily by surname of presenting author
A Collaborative Approach to Developing a Nickel Exploration Model in the Lake Johnston Greenstone Belt Ian Gregory^ John Miller^, Geoff Heggie^, Aurore Joly ^Norilsk Nickel Australia PTY LTD (ian.gregory@nomik.com.au) ^Centre for Exploration Targeting, The University of WA, Crawley WA The development of a predictive model for targeting nickel sulphide mineralisation is a critical element of future exploration in the Lake Johnston Greenstone Belt, Southern Cross Province of the Yilgarn Craton, Western Australia. The predictive model development is a collaborative research project between Norilsk Nickel Australia, The Centre for Exploration Targeting (UWA) and AMIRA (P710A). The aim is build upon previous studies to develop a holistic 4D geological, structural and geochemical model for the Maggie Hays and Emily Ann nickel sulphide deposits. This project provides a platform for academic research, with the ability to influence the directions of current and future exploration programs. The deposits occur within high strain zones, which are geometrically and structurally complex. Research is focused on developing a better understanding of stratigraphy, resolving a complex deformation history and developing models for the formation of nickel sulphide ore to aid in understanding terminations of the ultramafic units and the distribution of nickel mineralisation. Some key findings to date include; the development of an intrusive model for the emplacement of the ultramafic host rocks, a unique model for the formation of ore shoot geometry, strain analysis of the remobilized massive sulphides at Maggie Hays, and an understanding of deposit-scale PGE signatures.
Morphological Complexity and Diversity in the c.3.40 Ga Strelley Pool Chert, Pilbara Craton — Evidence for a Biogenic Origin Kathleen Grey ^ Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia (kath.grey @ doir. wa. gov. au) Objections to using coniform structure morphology as sole evidence for Paleoarchean life centre on the mistaken supposition that abiogenic processes can produce identical structures. For example, some researchers consider that coniform structures in bedded marine carbonates from the c. Australian Earth Sciences Convention 2008
3.40 Ga Strelley Pool Chert are misinterpreted as microbialites and that they either represent sedimentary structures or chemical precipitates. Such opposing opinions question the evidence for Paleoarchean life and undermine confidence in morphology as a biogenic indicator. However, recent studies of morphology in relation to facies distribution (Allwood et al., 2007, Precambrian Research, 158, p. 198-227) and detailed sedimentological work (Van Kranendonk in Van Kranendonk et al., (eds.). Earth's Oldest Rocks, Elsevier, p. 855-877) both demonstrate that morphology can be a reliable indicator of biogenicity. Both branching and tall-cylindrical columns exist alongside cones in the Strelley Pool Chert. Such structural diversity points to a biogenic origin. Proposed abiogenic mechanisms require a uniformity of chemical or sedimentary conditions, and are unlikely to produce highly complex mixed morphologies with discreet ranges of variability. Moreover, cones are difficult to generate abiogenically. No known, naturally occurring, abiogenic conical structures exhibit the association of characteristics typical of conical stromatolites. New morphological studies strongly support a biogenic origin for Strelley Pool Chert conical structures. Laminae are not isopachous when measured and therefore do not indicate precipitation. Moreover, some large Strelley Pool Chert cones have axial zones, a feature that differentiates conical stromatolites from abiogenic cones. Axial zones are diagnostic of several taxa of coniform stromatolites and are present in extant microbial mats, where their formation has been demonstrated to be a biological process (Walter et al., 1976 in Walter (ed.) Stromatolites, Elsevier, p. 273-310). Paleoarchean stromatolites are part of a morphological continuum extending from the Archean to the present day.
Perylene: a molecular marker for lignin degradation and a signal for the rise of vascular plants KM Grice\ Hong Lu^'^ Pia Atahan^ Christian Hallmann\ Erin James ^ Paul Greenwood^ and John Dodson"^ ^ Curtin University of Technology, Perth, Australia e-mail: (K.Grice@curtin.edu.au) ^ Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China ^ School of Earth and Geographical Sciences, University of Western Australia, Perth Australia ^ Austrahan Nuclear Science and Technology Organisation, Sydney, Australia Perylene is a polycyclic aromatic hydrocarbon (PAH) that has been extensively reported in recent marine, lake, and river sediments,
ABSTRACTS alphabeticafly by surname of presenting author
as well as peat. However, the source of perylene remains obscure and has been debated in recent years. The abundance and occurrence of perylene differs to that of other unsubstituted PAHs, which are largely attributed to combustion processes (Grice et al., 2007). One feature frequently reported for perylene is its increasing abundance relative to total organic carbon with burial depth in terrestrial soils, consistent with an in-situ source in the subsurface. Apart from sediments, perylene has also been observed in termite nests in tropical top-soils (Wilcke et al., 2002). We have studied the 6'^C and 6D and abundance of perylene and abundances of pollen and fungal spores in a soil profile from the Holocene. 6D values for perylene are in the order of those reported for methoxyl groups in lignin from extant wood (Bechtel et al., 2007). These results provide unequivocal evidence for a lignin degradation source for perylene. Lignin provides structural rigidity and plays other critical roles such as water transport in plants. Its recalcitrant nature makes it indigestible by mammalian enzymes, although some fungi and bacteria are able to degrade it readily. While a large number of studies report the occurrence of perylene in Mesozoic and Cenozoic sediments and oils, only a few published reports describe the presence of perylene in Palaeozoic sediments and oils. Perylene has never been reported from the Precambrian. Perylene is negligible in a large marine sedimentary sequence from the Neoproterozoic of Gondwana, and absent in Ordovician oils. This dataset suggests that perylene is absent in sediments pre-dating the evolution of vascular plants. In addition to the implications for the rise of vascular plants the significance of perylene across mass extinction boundary events will be discussed.
The Mt. Mulga barite-iron-oxide-coppergold mineralisation, Olary Domain, South Australia Griessmann. M \ Schmidt Mumm, A.^, Conor, C.^Seifert, T.^ ^ TU Bergakademie Freiberg, Freiberg, D-XXX, Germany (martin.griessmann@web.de) School of Earth and Environmental Sciences, The University of Adelaide, Adelaide, SA 5005 The Mt. Mulga barite-iron-oxide-copper-gold deposit lies about 25 km north of Olary and 120 km west of Broken Hill in the Olary Domain, Curnamona Province. The mineralisation is hosted by an overturned meta-volcano-sedimentary sequence within the lower Willyama Supergroup. The main ore body has BaO content of up to 60 wt.%, Cu-values up to 5050 ppm and Au-values up to 1.3 ppm. All other base metals besides Cu show inconspicuous values below 20 ppm. Barite,
coarse crystalline magnetite and quartz are the main minerals of the ore bodies. The Cu-Au mineralisation consists of disseminated chalcopyrite, bornite and native gold. From the main ore body, a seam-like extension of the mineralisation can be traced along strike for at least 1.6 km in southeasterly direction with a gradual mineralogical change to a quartzironstone. This change correlates to a systematic variation of the chondrite normalized REE-patterns along strike. Proximal samples from the main ore body have a strong, positive Eu-anomaly and frequently a negative Ce-anomaly while the distal quartz-ironstone extension has no or even a slightly negative Eu-anomaly and no Ce -anomaly. d^'^S-values of chalcopyrite ranging from -1.5 to +3.1 %o and in barite from +6 %o to +16.3 %o. The ^"^Sr/^^Sr-ratios of barite are in between 0.7089 and 0.713. The proposed model for the genesis of the mineralisation is that reducing, metakich hydrothermal fluids reacted with the non-marine oxidising water of the Willyama basin leading to the precipitation of barite and iron-oxides. Cu-Fesulphides and native gold are suggested to be syngenetic to this process. The ^^Sr/^^Sr of barite and the d^'^S values of chalcopyrite reflect the composition of the hydrothermal fluid derived from a crustal source. The (f'^S of barite relates to the sulphate from the basin water
Volcano and Earthquake Risk in the Asia-Pacific Region Jonathan Griffin^ Alanna Simpson\ Phil Cummins', John Schneider' ^ Geoscience Australia, GPO Box 378, Canberra, ACT2601, Australia (alanna.simpson@ga.gov.au) The Asia-Pacific region is home to well over half the world's population and is also the focus of some of earth's most intense geological activity. It is no surprise therefore that geological hazards, in particular earthquake and volcano hazards, make the Asia-Pacific region the scene of some of the worlds most lethal natural disasters. While this is evident form a perusal of historical data relating to natural disasters, it is not clear how well such historical data can be used as a guide for high-impact events that might be expected in the future. This uncertainty is due to (1) how poorly extreme geological events having long recurrence intervals are represented in the relatively short historical record, and (2) the failure of the historical record to account for recent demographic trends, in particular the explosive growth of population in the Asia-Pacific region and its rapid urbanisation during the century. We present here two novel techniques for assessing the potential impacts of volcanic and earthquake events on human population in the Asia Pacific region. continued next page... Australian Earth Sciences Convention 2008
121
122
ABSTRACTS alphabetically by surname of presenting author
For earthquake, risk, we have considered that the potential future high-impact events will be driven by the probability that an earthquake might occur in or adjacent to one of the many megacities of the Asia-Pacific region. Earthquake probabilities near megacities are calculated from catalogue data, and these are combined with a rough criterion for damage based on earthquake ground motion, to asses potentially affected populations. We present preliminary results of these analyses, which suggest the potential for earthquakes and volcanoes in the Asia-Pacific region to cause future 'mega-disasters', for which affected populations may be much larger than the numbers indicated by the historical record.
The impact of government precompetitive geoscience data on mineral exploration in WA. Tim Griffin
^ Geological Survey of Western Australia, Mineral House, 100 Plain Street, East Perth WA 6004 (tim. griffin @ doir. wa. gov. au) Western Australia is endowed with an impressive inventory of world class mineral deposits. In order to replace the resources currently being mined or developed as part of the resources boom in WA new discoveries are required. These will come from re-evaluating existing exploration data, and from stimulating exploration by providing precompetitive geoscience data in underexplored "greenfields" areas. Access and outcrop are often poor in greenfields areas, and deposits may be hidden beneath regolith or thin sedimentary cover with no obvious surface expression. For industry, exploration in these areas involves high cost, highrisk, model-driven target generation. For governments the challenge is in stimulating exploration by providing pre-competitive geoscience datasets that reduce the level of those risks. Since 2004/05, the Government of WA has provided an extra AU$3 million a year to the Geological Survey of Western Australia to accelerate delivery of pre-competitive geoscience information to explorers. In the first four years of this program, 2 million line kilometres of airborne magnetics and radiometrics surveys have been flown, a number of ground gravity surveys have been conducted, soil and laterite geochemistry surveys undertaken, and a deep seismic survey completed. Before the start of the program only 30% of Western Austraha's land area was covered by 400 metre line-spacing airborne magnetics. This has been increased to over 70%, and new surveys are planned that will increase the coverage even further. The new geophysical data is used as part of an integrated approach to geological mapping by GSWA, which is crucial to the provision of robust Australian Earth Sciences Convention 2008
interpretations of geological history, tectonic setting and of mineral systems. These interpretations can be fed into regional exploration models to generate exploration programs and targets. They are supported by the acquisition of new geochronology, isotope data and whole rock geochemistry, and by compilations of known mineral deposits and mineral occurrences from GSWA's mines and mineral deposits database and mineral exploration reports database.
The Proterozoic: Hiding Archean in the basement W.L. Griffin^ Graham Begg^Suzanne Y. 0'Reilly\ Lev Natapov^ ^ GEMOC, Dept of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia (bill, griffin @ mq. edu. au) ^ Minerals Targeting International PL, 17 Prowse Street, West Perth, WA 6005, Australia (graham, be^s @ hispond. com) The Global Lithospheric Architecture Mapping (GLAM) project integrates geophysical, geological, and geochemical data on the crust and lithospheric mande. Interpretation of this data over the past 5 years has generated a map of lithospheric composition and architecture that suggests that at least 60% of sub-continental lithospheric mantle (SCLM) may have an Archean parentage. Of particular significance is the inference that most preserved Proterozoic crust overlies Archean SCLM that has been variably refertilised and metasomatised by mande melts associated with convergent margin, post-collisional, and mantle plume processes. These interpretations suggest that consideration of lithospheric preservation and recycling is crucial to understanding Earth evoludon. In a recycling model, ancient, rigid, buoyant SCLM survives the rifdng and accredonary processes of supercondnent cycles, whilst juvenile, fertile, dense SCLM typical of island arcs is destroyed. At least 20% of the present SCLM may be such ferdle SCLM that has yet to be recycled. This SCLM has lower seismic velocities than the more depleted (Fe poor) SCLM that typifies Archean terranes. Although geochronological and isotopic (Hf, Nd) studies indicate that juvenile Proterozoic crust may be less extensive than previously believed, a recycling model must still account for significant amounts of juvenile Proterozoic crust. Only some of this crust can be attributed to obducdon. Rifting and detachment of variable thicknesses of crust, ranging from upper crustal to whole crustal secdons, may be a contribudng process. If emplacement of new crust occurs under extensional tectonic condidons, then detecdon of
ABSTRACTS 123
alphabetically by surname of presenting author
older crust may be difficult. Geodynamic reconstructions need to recognise that relatively rigid and bouyant depleted SCLM influences plate geodynamics through the transfer of stress and the termination and initiation of subduction. It is possible to reframe our understanding of crustal processes as secondary responses to processes affecting the SCLM from below as well as at plate boundaries.
Using Novel Prospectivity Mapping Tools, Self Organising Maps (SOMs), Fuzzy Neural Networks (FNNs), and Radial Basis Functional Link Nets (RBFLNs), to Evaluate the Orogenic Gold and lOCG Potential of Finland David Groves \ Vesa Nykanen^, Gary Raines^ ^University Of Western Australia ^GTK '^Consultant-USGS Rtd Artificial neural networks (ANN) are capable of dealing with non-linear relationships, which may provide interesting new insights into the formation of mineral deposits. The ANN's can be used to classify data into categories by using known examples for training as is done in supervised ANN techniques, such as Radial Basis Functional Link Nets (RBFLN). Alternatively, unsupervised ANNs, Self Organising Maps (SOMs) or Fuzzy Neural Nets (FNNs) can find the natural clustering within the data, without known examples for training. In this study, the SOM, FNN, and RBFLN techniques are applied to generate a series of prospectivity maps for orogenic gold and iron-oxide Cu-Au (lOCG) deposits within the Northern Fennoscandian Shield, Finland. The area is considered highly prospective, yet clearly underexplored. The supervised RBFLN performs better than previously-applied statistical weights-ofevidence or conceptual fuzzy logic methods, and equally well as the logistic regression method, when applied to the same geophysical and geochemical data layers that act as proxies for conceptual geological controls on orogenic gold deposits for the prospectivity mapping. By weighting the training feature vectors in terms of the size of the gold deposits, classification of the RBFLN results provides an improved prediction of the distribution of the more important deposits and occurrences. The SOM and FNN techniques, when applied to define natural clusters for the same data applied to lOCG prospectivity, produces results that are clearly analogous to the previously published conceptual fuzzy logic and new RBFLN models. This demonstration suggests the unsupervised neural nets can provide meaningful prospectivity maps in situations where insufficient training is available for supervised methods.
Australian Junior Exploration Floats, 2001-2006, And Their Implications For IPOs Pietro Gui^-^ Oliver P. Kreuzer^'^'^ Michael A. Etheridge^'^ ^ ARC National Key Centre for the Geochemical Evolution and Metallogeny of Continents, Macquarie University, North Ryde, NSW2109 Centre for Exploration Targeting, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009 (okreuzer@cylleneMwa.edu.au) ^ Western Australian School of Mines, Curtin University of Technology, Kent Street, Bentley, WA 6102 ^ Tectonex GeoConsultants Pty Ltd, 25 Darvall Street, Balmain, NSW 2000 An analysis of 179 junior mineral exploration floats, listed on the Australian Securities Exchange (ASX) between July 2001 and June 2006, helped to build a basic understanding of the strategy and business structure of these companies. The "typical" junior explorer raised A$4 million at initial public offering (IPO) to finance a two-year, mainly greenfields exploration program. The favourite project location was Western Australia. The preferred target commodities were gold and nickel, although uranium rapidly increased its share after the financial year 2004-05. The capital raised at IPO entitled its investors to approximately half of the company, with the balance in the hands of the promoters, vendors and/or seed capital investors. Of the A$4 million raised at IPO, it intended to spend approximately two-thirds on exploration, while the remainder was absorbed in corporate overheads and the costs of the IPO. Once these were paid, ongoing corporate overheads averaged approximately 28% of its total operational expenditure. However, given an average total annual expenditure of approximately A$2.6 million, most juniors held insufficient capital reserves to meet operational costs beyond a time frame of two years. As at October 2006, 9% of the companies were in the process of mine construcfion, whereas 6% had made it to producer status. The lead time from listing to production ranged from 1.5 to 53 months giving a median of 28 months.
Australian Earth Sciences Convention 2008
124 ABSTRACTS aiphabeticaiiy by surname of presenting author
Structural Controls on Mineralisation, Bonaventura Prospect, Kangaroo Island, South Australia. Gum. J . C \ Swain, G. \ and Schwarz, M.\ ^ Monax Mining Ltd, llA Croydon Road, Keswick SA 5035 (jgum@monaxmining.com.au, mschwarz@ monaxmining. com. au, gswain@monaxmining. com. au) Lead-zinc-copper mineralisation was originally discovered by prospectors in the Bonaventura-Perseverance area in the 1890s. The thin, oxidised zone and narrow vein systems discouraged any significant mining. Minimal follow-up exploration was undertaken until 100 years later when the South
Australian Department of Mines and Energy
conducted a N-S drilling traverse across the area. One hole intersected 10.8% Zn, which rekindled interest in the area. In 2004, Havilah Resources NL investigated the area, following up the earlier drilling. Havilah drilled 32 shallow aircore holes and intersected highgrade zinc mineralisation at shallow depth (less than 40 m), with assays ranging up to 26.9% Zn, accompanied by up to 9.4% Pb. This drilling was angled at 60° towards OSS^'mN. This is approximately perpendicular to the regional structural fabric and lithological layering. They were unable to effectively join mineralised intercepts together. Monax Mining Ltd followed this drilling with deeper RC drilling down to 175m. This drilling was angled at 60° towards 000°mN and was also unable to prove continuity of mineralisation between sections. The majority of the area contains shallow sub-crop but little outcrop and a costeaning program was undertaken to provide structural and lithological information to assist with the interpretation of the distribution of mineralisation. The costeaning showed that the mineralisation is contained in a 015° trending vein system. This broadly corresponds to historic soil sampling and the distribution of prospecting pits. The mineralisation sits in a flexure of the regional shear zone. The axis of this flexure corresponds to the distribution of the vein system. The mineralisation is interpreted to be either a younger primary system or remobilised from older mineralisation and deposited in a dilational zone within the Cygnet-Snelling Shear Zone. Further drilling is currently being undertaken perpendicular to this fracture zone with the expectation of improved resource delineation.
Australian Earth Sciences Convention 2008
Physical Properties of Ar, Kr and Xe In Earth's Deep Interior Seema Gupta\ S.C. Goyal^ 'Dept. Of Physics, Agra College, Agra-282002 ^Department of AppL Sciences, Faculty of Engineering and Tech., R.. B. S. College, Bichpuri, Agra-28200 In the present study the expressions for the Bulk Moduli, Young Moduh (E), Poisson's Ratio (a), First order pressure derivative of bulk and shear moduli, Seismic wave velocity (Vp & Vs) are derived for rare gas solids. The expressions are used to compute the values of these constants at different pressure for Ar, Kr and Xe. Further the computed values of these constants are used to evaluate Debye temperature (Oac) and Gruneisen parameter {y) parameter. The computed values of Acoustic Debye temperature and Gruneisen parameter are in excellent agreement with the experimental results. Thus this study may be useful in analyzing the Seismic wave velocities in earth deep interior. PACS number(s): 63.70.+h, 64.30.+t, 05.70.Ce, 65.40.-b
The giant Carajas jaspilite-hosted iron deposits: geological setting, fluid geochemistry and genetic model
Steffen Hagemann\ Rosaline Figueiredo e Silva^, Lydia Maria Lobato^ ^ Centre for Exploration Targeting, School of Earth and Geographical Sciences, University of Western Australia, Australia, Crawley, Western Australia 6009 ^Universidade Federal de Minas Gerais, Centro de Pesquisas Prof Manoel Teixeira da Costa-Instituto de Geociencias. Av. Antonio Carlos 6627, Campus Pampulha, Belo Horizonte, MG, 31270.901, Brazil The Carajas iron deposits located in the southern part of the state of Para in Brazil were discovered in 1967 and have produced about 70 million tons of iron ore annually. The protoliths to iron mineralization are greenschist facies metamorphosed jaspilites and basalts with the latter under- and over-laying the iron orebodies. The major Serra Norte Nl, N4E, N4W, N5E and N5S iron ore deposits of the Carajas Mineral Province are distributed along, and structurally controlled by, the Carajas fold. Varying degrees of hydrothermal alteration have affected jaspilites to form high-grade ore. The mineralogical, geochemical and isotopic changes from protore jaspilites to high-grade iron ores suggests a hydrothermal origin for hard-ore via interaction with an early-stage medium to high salinity Ca-rich and Ca-Fe-rich, relatively reduced
ABSTRACTS alphabetically by surname of presenting author
magmatic fluid, which leached silica and formed magnetite. This fluid evolved to more oxidizing conditions, with the advance of martitization, increased in the REE concentration and microplaty hematite precipitation in veins and martite in adjacent wallrocks. Low values of oxides in the ore zone suggest mixing with meteoric water during this intermediate hydrothermal alteration stage. The predominance of oxidized phases such as anhedral and euhedral/tabular hematites, low salinity, Na-rich fluids, increase in sulfur isotopic values, and decreasing oxygen isotopic values towards late hematite types indicate that the advanced alteration stage is dominated by meteoric waters. The magmatic-meteoric hydrothermal mineralization model for the Carajas hard ores may have a genetic link to the numerous Proterozoic magmatic hydrothermal mineral systems in the Carajas Mineral Province such as lOCG and intrusion-related Cu-Au..
The Upper Loddon ^Deep Lead' Palaeodrainage Systems are Discontinuous Due to Mid Tertiary ENETrending Faults. Sarah K. Hagerty^ Jon Fawcett^, John A. Webb^ ^ Environmental Geoscience, La Trobe University, Bundoora, Victoria (S.Hagerty@latrobe.edu.au, John. Webb @ latrobe. edu. au) ^ Future Farming Systems Research Division, Department of Primary Industries, Bendigo, Victoria {Jon. Fawcett @ dpi. vie. gov. au) The Upper Loddon Calivil Formation, or 'deep leads', have been intensely studied since the 1800's because they are an important gold-bearing alluvial system and, more recently, because they are an important aquifer. Despite this, the distribution of the sub-basaltic sediments has been a source of confusion; miners reported 'lost' leads and drilling often recorded the absence of deep lead sediments where they had been predicted to exist. With increasingly dry chmatic conditions within southern Australia there is an increasing demand to utilise groundwater resources. A detailed understanding of the distribution of deep lead sediments is critical in the development of sustainable groundwater management plans. Joint studies between DPI, Victoria and La Trobe University provide the most accurate and detailed mapping of the Upper Loddon deep lead sediments available, using an extensive bore log database. The studies concluded that the Upper Loddon deep lead sediments are discontinuous: they form a series of basin-like deposits up to 40-70 m thick, separated by areas where the sediments are thin to absent. This distribution is controlled by contemporaneous Miocene to Pliocene ENE-
trending faults that have now been more accurately located. The faults trend across the central highlands of Victoria, where numerous deep lead systems exist. A new conceptual model of deep lead deposition and faulting is presented that explains the current mapped extent of deep lead material within the Victorian Uplands and confirms the structural control on deep lead distribution that was recently identified. The implication of this work is that the complexity of deep lead distribution needs to be considered when models and groundwater management plans attempt to define hydrogeological parameters of the deep lead aquifer. The faults that control the outcomes of this research suggest that upland deep lead systems throughout central Victoria may require remapping and should not be assumed to be continuous deposits.
Foraminiferal tracers for climate and water-quality changes in Permian interior seas in northeastern Gondwana David W. Haig School of Earth and Geographical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia (david. haig@uwa. edu. au) Interior rift basins along the present western margin of the Australian continent, extending from Timor to the Perth Basin, provide a record of Permian marine incursions deep into the interior of eastern Gondwana. Climate and water-quality conditions are reflected by the marine biota preserved in the deposits of these seas that stretched along an approximately north-south transect with more open-marine conditions in the north. Following initial glacially influenced sedimentation during the Asselian, marine sedimentation took place in shallow basins that had a very low gradient seafloor. Biogenic carbonate deposition (e.g. during the late Sakmarian-early Artinskian, and during the Wuchiapingian-Changhsingian) alternated with siliciclastic sedimentation (e.g. during the Kungurian-Roadian). Pronounced sand/shale cyclicity is a feature of most of the deposits. Within the interior rift basin system, foraminifera are best known from the upper Sakmarian-lower Artinskian (dry, temperate climatic phase), Kungurian (wet, cool climatic phase), and the Wuchiapingian-lower Changhsingian (dry, temperate climatic phase). The Guadalupian is poorly represented in the interior rift basins. Foraminiferal assemblages in the carbonate units are dominated by lagenids, and at some levels by porcelaneous species, with rare endothyacean and tetrataxacean taxa. Fusulinaceans are confined to the Timor deposits. Assemblages from shales are characterized by an abundance of organic-cemented agglutinated foraminifera that resemble modern continued next page.. Australian Earth Sciences Convention 2008
125
126 ABSTRACTS alphabetically by surname of presenting author
estuarine species. This presentation aims (1) to review the distribution of foraminifera along the north to south transect and to differentiate possible climatic and water-quality (mainly salinity and dissolved oxygen) influences on the biota; (2) to examine faunal variability through time at selected locations along the transect; (3) to contrast the foraminiferal distributions with those of marine macrofossil groups; and (4) to recognize biogeographic affinities of the foraminifera.
Timor stratigraphy reconstructed: 155 Ma to present David W. Haig School of Earth and Geographical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia (david. haig@uwa. edu. au) Post Middle Jurassic sedimentary deposits in Timor belong to four tectonostratigraphic units. The Australian-Margin Megasequence of Late Jurassic to early Late Miocene age overlies the older Gondwana Megasequence. The Synorogenic Melange formed at least partly through diapirism during orogenesis. The Banda Terrane contains upper Mesozoic to Paleogene siliciclastic units as well as Eocene and Miocene shallow-water limestones of Asian affinity. The Synorogenic Megasequence accumulated in basins adjoining the emerging mountains of Timor during the Plio-Pleistocene. This presentation reports on some of our recent findings. (1) Limestones on Cablac Mountain belong to the Upper Triassic-Lower Jurassic rather than to the Miocene — with significant implications for the structural interpretation of Timor. (2) The first detailed map of a "fatu" (limestone mountain) complex in Timor has shown that this is a thrustfault stack containing units of various ages ranging from Triassic to Lower Miocene, rather than a monolithic Lower Miocene limestone as previously interpreted. (3) We have evidence suggesting that the Australian Margin Megasequence accumulated in deep water on an Australian continental terrace similar to Exmouth Plateau rather than on the Australian continental slope as previously interpreted, and have recognized that these sediments remained as friable chalk and carbonate ooze until deformation commenced during the Late Miocene — with significant implications for understanding the structural deformation and diagenetic history of the sediments. (4) By defining the age of the youngest carbonate pelagites of the Australian Margin Megasequence and the oldest units of the Synorogenic Megasequence we have placed 9.8-5.6Ma GTS2004 age constraints on the initial collision of the Banda Arc and the Australian continent. (5) We have recognized a very young (probably Pleistocene) crush breccia with clasts of Australian Earth Sciences Convention 2008
mixed tectonostratigraphic affinity along a highangle fault on the north-east side of Cablac Mountain, which was formerly interpreted as the basal conglomerate of a lower Miocene limestone unit — providing a window into the structural history of Timor post the main phase of thrust fauhing
Provenance of Paleozoic sandstone in the Canning Basin using SHRIMP U-Pb dating of detrital zircons. Peter W. Haines\ Michael T.D. Wingate^
^ Geological Survey of Western Australia, 100 Plain Street, East Perth, Western Australia 6004. (peter. haines@doir. wa.gov. au) (michael. wingate@doir. wa.gov. au) The Canning Basin is a large intracratonic sedimentary basin of Ordovician to Cretaceous age in northern Western Australia. It contains several recognized petroleum systems of Paleozoic age and is currently undergoing an exploration revival. Potential petroleum reservoir sandstones are present at a number of stratigraphic levels, but lateral distribution, thickness and facies changes are often poorly constrained due to scarcity of outcrop and drill core. Detrital zircon dating can help by potentially linking sandstone bodies to specific source terrains in the basin hinterland margin. Such studies may help to distinguish separate sand bodies with similar stratigraphic position but physically unconnected, provided they have distinct provenance. It may also constrain the timing, duration or even existence of the hypothesised Larapintine Seaway between the Canning and Amadeus basins because the abundant Ordovician sandstone in the latter has a uniform and well characterized detrital zircon age signature distinct from local basement sources. Preliminary data from the marine Ordovician Acacia Sandstone Member and age equivalent sandstone units suggest that these may represent several separate lowstand sand bodies derived from different source terrains, the North Australia Craton and recycled Neoproterozoic rocks respectively. The Carranya Formation around the NE basin margin also has a similar provenance to the latter. Only the Early Ordovician Wilson Cliffs Sandstone of the SE Canning Basin shows any similarity to coeval sandstones of the Amadeus Basin, and this potential link is being tested with further samples from SE Canning Basin. Non-marine Devonian (Tandalgoo Formation) and deltaic Carboniferous (Anderson Formation) sandstone shows a broad spread of ages suggesting a mixture of older centralian (Amnta) basement and overlying sedimentary sources, the age spectra being broadly similar to previously reported Silurian-Devonian sandstone from the Amadeus and Georgina basins. All are likely derived from the uplifted Alice Springs Orogen in central Australia.
ABSTRACTS alphabetically by surname of presenting author
The impact of impacts: impact as a geological process and significance in economic geology. Peter W Haines^ ^ Geological Survey of Western Australia, 100 Plain Street, East Perth, Western Australia 6004. (peter. haines@doir. wa.gov. au) Impact, or accretion, is the process by which all planets in the solar system formed, and for most rocky bodies it remains the most important surface geological process. Earth is an exception only because plate tectonics, and an active hydrosphere and atmosphere, act to rework the crust at a rate far in excess of the ongoing accretionary process. Nonetheless, Earth has an impact record of craters and their ejecta stretching back to the Archaean. Approximately 180 impact structures are confirmed world-wide, with a disproportionate abundance in the western half of Australia. Impact processes are unique in geology because of their ultra high strain rate and short duration, and the temperature* pressure* time relationship of shock metamorphism is well outside the field of other metamorphic processes. The extraordinary energy release in large impact events not only damages the crust, but can have profound effects on the biosphere as demonstrated by the Chicxulub impact at the Cretaceous-Tertiary boundary. Other mass extinctions may also be related to impact, but the jury is still out. Although impact is not traditionally linked with economic geology, it was ironically the desire to mine the supposed iron meteorite buried within Barringer crater (Meteor crater) in Arizona, which led to the first scientific examination and acceptance of an impact crater. It is not widely appreciated that an estimated 25% of the world's impact structures are associated in some way with economic or subeconomic mineral and petroleum resources. The relationship may be progenetic (modification or exposure of pre-existing resources, e.g. Vredefort), epigenetic (formed as a direct result, either during or shortly after impact, e.g. Sudbury) or epigenetic (from subsequent processes facilitated by the impact event, e.g. Red Wing crater, >130 million barrels oil; distal Chicxulub-related deposits, >30 billion barrels oil). In most cases economic discoveries related to impact structures and distal deposits preceded recognition of impact genesis. A better understanding and appreciation of impact as a geological process may accelerate the discovery of impact-related resources.
The Cleanskin Structure: A Preliminary Report on a Large Impact Structure in the Mesoproterozoic South Nicholson Group, Northern Australia. Peter Haines^, Ian Sweet\ Ken Mitchell^ ^31 Courtice Close, Fadden, ACT, 2904 (ian. sweet @ homemail com. au) ^ Geological Survey ofWA, 100 Plain St, East Perth, WA, 6004 (Peter.Haines@doir.wa.gov.au) ^ 81 Fern St., Gerringong NSW, 2534 (kandmitchell @ aapt. net.au) The Cleanskin Structure (Lat 18°09 S, Long 137°57 E) is a circular feature centred 320 km NW of Mount Isa, straddling the NT-QLD border. At least 15 km in diameter, the western half is poorly defined because of overlying Cretaceous strata. Anomalous fold and fault patterns in otherwise mildly deformed rocks were noted during remapping of the Mount Drummond 1:250 000 map area in 2001; the circular nature of the structure was recognised from Google Earth images during later map compilation. It lies wholly within the Constance Sandstone, in the lower part of the early Mesoproterozoic South Nicholson Group. The inner several kilometres is a structural dome with at least three repetitions of the same two members of Constance Sandstone separated by reverse (thrust?) faults. These faults are circumferential in pattern, and appear to be displaced by E-NE and W-NW oriented faults probably related to regional deformation. Preliminary field observations in the SE quadrant located shatter cones in sandstones 3.5 km from the centre, and bands of brecciated sandstone and siltstone tens of metres in extent. Melt rocks were not recognised, but most sandstone is strongly indurated and has a ''quartzite" appearance. Thin sections reveal low level shock effects in quartz grains — multiple planar fracturing, many showing "feather features", grain mosaicism, and probable planar deformation features. Shatter cones and petrographic shock effects indicate that the site is an impact structure, but the low levels of shock and structural relationships suggests it is deeply eroded. Because 1-3 km of South Nicholson Group is estimated to have existed above the preserved levels, it is likely that the original crater formed in the uppermost South Nicholson Group, implying an original crater over 20 km diameter. The time of impact is constrained between deposition of the South Nicholson Group (1400-1500 Ma based on regional correlation), and the overlying undeformed Cretaceous rocks, but most likely occurred prior to regional deformation during the Mesoproterozoic or Neoproterozoic.
Australian Earth Sciences Convention 2008
127
128
ABSTRACTS alphabetically by surname of presenting author
Capel and Faust basins — Geoscientific Assessment of an Offshore Frontier Region
Mineral Potential Mapping — Geoscientific Advice for Public Policy: an Example from Western Australia
Takehiko (Riko) Hashimoto \ Robert Langford^ Nadege Rollet\ Karen Earl\ George Bernadel^
L. Y. Hassan^
^Petroleum and Marine Division Geoscience Australia GPO Box 378 Canberra ACT 2601 Australia (riko.hashimoto@ga.gov.au) The Capel and Faust basins are located at water depths of 1300-2500 m in the Remote Eastern Frontiers region, offshore eastern Australia. Geoscience Australia has been investigating the geology and marine environment of this frontier area as part of the Australian Government's Big New Oil (2003-2007) and Energy Security (2007-2011) initiatives. Pre-existing geoscientific data coverage in the area is limited, consisting of seismic profiles acquired during the 1970s to early 2000s and two DSDP drill holes. Recent surveys by Geoscience Australia have acquired new data, which are undergoing analysis for petroleum prospectivity assessment and marine environment classification. The Capel-Faust S302 seismic survey (2006-2007) generated c. 6000 line km of high-quality 2D seismic and regional magnetic and gravity data. This survey revealed the existence of numerous new depocentres, some up to 150 km long and 40 km wide, with a possible total sediment thickness of up to 7 km. Initial interpretation has identified a pre-rift succession, up to three syn-rift phases, and two post-rift carbonate packages. The RV Tangaroa survey in late 2007 acquired high-resolution multibeam bathymetry, gravity and magnetic geophysical data. The multibeam bathymetry revealed large-scale features such as volcanic cones, sill-forced fold complexes, slumps, and polygonal faulting at the seafloor. 46 sites were also visited for the collection of basement, volcanic rock, sediment, and biological samples. Underwater camera footages of the seafloor morphology, biota and, in some instances, fluid escape were captured at all sampling sites. Further work will focus on the integration of the available data sets in order to define the rift basin architecture and tectonostratigraphic history. The project outputs will contribute to improving our understanding of the petroleum prospectivity of the frontier basins, and to underpinning future marine planning in the region.
^Geological Survey of Western Australia, 100 Plain St, East Perth, Western Australia 6004, (lee. hassan @ doir. wa. gov. au) The Western Australian Government is endeavouring to establish a conservation reserve system that is comprehensive, adequate and representative and aims to have 15% of the State in protected areas by 2029. To date, 54 whole and part pastoral leases totalling 5.79 million hectares have been purchased by Government which will increase the conservation estate from 6.7% to 9% of WA. These pastoral leases lie in some of the most prospective parts of the State. The Geological Survey of Western Australia (GSWA) was given 6 months to carry out a prospectivity study of these former pastoral leases. In areas recently covered by the GSWA's mineral prospectivity assessment program this was relatively straightforward. However, in areas not yet covered by this program in the southern half of WA, the assessment of mineral prospectivity was much more of a challenge especially in areas where there is minimal exposure, or no recent geological mapping. In these areas, GSWA's 1:500 000 solid geology dataset was not always reliable. Aeromagnetic, radiometric and Landsat images were used to assist with geological interpretation. Mineral deposits and historic and producing mines were located using GSWA's MINEDEX database. Open-file exploration reports and company reports to the Australian Stock Exchange were also used in the assessment of the geology and prospectivity. For each pastoral lease, tract maps were constructed for each commodity likely to be found in the area with tracts being ranked from low to high prospectivity; a level of certainty was also assigned to each tract. These tract maps were combined to form an overall prospectivity tract map for each pastoral lease. Parts of most pastoral leases are moderately to highly prospective for a variety of mineral commodities. For this reason. Government agreed that most of the former pastoral leases would be created as unclassified conservation parks in which exploration could continue. Government also agreed to exclude advanced projects from the reserves.
ABSTRACTS alphabetically by surname of presenting author
The Geophysical Signatures Australia's Meteorite Craters
of
P J Hawked M C Dentith^ ^ School of Earth and Geographical Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley 6009 (phil hawke @ optusnet. com. au) To date more than thirty impact structures have been discovered on the Australian continent. New structures are being discovered at a rate of about one every year, with geophysics being a key tool in the identification of candidate structures for further investigation. Past compilations of the geophysical signatures of impact structures, particularly of their potential field responses, have focused on structures formed in mainly crystalline targets (e.g. Pilkington and Grieve, 1992, Rev. of Geophys., v.30, p.l61181). From these studies, the expected gravity response is an overall low due to fracturing of the target rocks, with a possible local high due to structural emplacement of denser material in the central uplift. An overall demagnetisation of the target rocks by high shock pressures is also expected, although central magnetic highs may also be produced by remanently magnetised melt or the uplift of magnetic rocks from depth. The geophysical signatures of fifteen Australian impact structures are discussed. More than three quarters of these were formed in either Phanerozoic basins or mildly-deformed Proterozoic sedimentary rocks. The potential field responses of these structures show a greater variability than was expected, particularly between structures that were formed in different types of target rock. A positive gravity response covers four structures formed in clastic sedimentary rocks deposited in a Phanerozoic basin, which may be due to the emplacement of denser rock into the central uplift. A decrease in density due to brecciation is not apparent in this target rock type. Furthermore, it is suggested that by collapsing pore space and removing water, the density of wet sedimentary rocks may be locally increased by impact. Circular magnetic anomalies are found outside the central uplift of six impact structures formed in either Phanerozoic or weaklymetamorphosed Proterozoic sedimentary basins. These can be related to features reflecting the internal structure of the crater.
Discovery of a Large Palaeochannel During Exploratory Groundwater Investigations at Glen Innes, NSW Graham Hawkes^ and Ralf Stoeckeler^ Parsons Brinckerhoff, ghawkes @pb. com. au Glen Innes Severn RStoeckeler@ gisc. nsw. gov. au
Sydney. Council
The recent drought across regional New South Wales and the rest of Australia has caused water authorities to seek alternative sources to supplement existing water infrastructure during drought conditions. At Glen Innes, in northern New South Wales the Glen Innes Severn Council recognised that groundwater was a potential local valuable resource and initiated a groundwater resource investigation program to assess the groundwater resources close to the town and existing water supply infrastructure. Glen Innes is located within the Border Ranges in north eastern New South Wales, ten kilometres east of the Great Dividing Range. The geological targets include recent alluvium associated with the existing river systems, granites and metasediments of Permian age. Tertiary basalts and structural features such as regional fault systems, lineaments and axes of synclines or anticlines. Two of the four test bores, located 200 metres apart, penetrated vesicular Tertiary basalt and intersected a previously unknown six metre thick palaeochannel, 74 metres below ground level. The palaeochannel is composed of very well sorted medium to coarse grained quartzose sand and underlain by basalt. Palaeochannels in the Glen Innes region are also known as deep leads and have been previously mined as rich sources of tin. The two successful test bores were converted to production bores. Groundwater within the palaeochannel was of good quality and isotopic dating suggests the water is between 3700 and 6110 years old. Test pumping indicated the boreholes are hydraulically linked through the palaeochannel and can sustain yields of between 1.9 and 6.0 L/sec assuming no other boundaries are intersected. Additional work is required to map the extent of the palaeochannel and assess the long term groundwater potential of this groundwater resource.
Australian Earth Sciences Convention 2008
129
130
ABSTRACTS alpliat?ettealfy by mrmmB of prasentlitg author
Large Igneous Provinces, Mantle Plumes and Crust Generation Chris Hawkesworth^ ^Department of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 IRJ. UK (c.j.hawkesworth@bristoLac.uk) Large Igneous Provinces (LIP) represent major igneous events that are typically associated with the presence of mantle plumes. Mantle plumes are invoked in the generation of continental crust in the Archaean and the early Proterozoic; the implication is that they reflect deep-seated thermal instabilities, and that the associated magmatism is therefore unrelated to shallow level tectonic processes. In detail, the arguments are more complex. It remains difficult to identify mantle plumes on the basis of geochemistry, both because mantle plumes are physical phenomena, and because it is only occasionally possible to infer the depth of origin of intraplate material on the basis of geochemistry. Unless the potential temperatures are exceptionally high, melting will not occur in mantle plumes under thick continental hthosphere. Thus extensional tectonics may also be involved in the generation of large igneous provinces in continental areas. Geochemistry is used to distinguish intraplate basalts from those generated in other tectonic settings, but only some of those basalts may be associated with mantle plumes. The key aspect of magmas that have been associated with mantle plumes is that they have relatively high volumes, and melt generation rates - they are volume anomalies that necessarily reflect some form of physical anomaly in the melt generation zone, whether that is temperature or volatiles. Different LIPs appear to have different relative contributions from the plume material and the continental lithosphere, and they also appear to be characterized by different eruption rates, and hence by implication, melt generation rates. It therefore remains difficult to sustain a one model fits all for the generation of continental flood basalts. The Hnks between mineralization and certain continental flood basalts will be explored.
The Geodynamic Setting and Magmatic Controls on Genesis of World Class lOCG Ore Deposits Nick Hayward BHP Billiton, L34 Central Park, 152-158 St Georges Terrace, Perth, WA 6000, Australia Iron-oxide CuAu (lOCG) deposits are an attractive target for exploration and mining, especially in Australia which hosts the supergiant Australian Earth Sciences Convention 2008
Olympic Dam Mine. Compared to Porphyry Cu(Au,Mo) deposits, they typically have higher hypogene metal grades (>1% Cu eq.), stronger geophysical anomalism and better preservation potential, all better suited to exploration under cover. Against this, lOCG deposits are an order of magnitude rarer than porphyry deposits and less well understood. Controversies exist over the fluid and metal sources involved in lOCG ore genesis. Resolving these controversies depends on directly linking the range of deposit styles to the specific geodynamic and magmatic settings in which they form. It also requires advances in understanding magma evolution where melt mixing may be involved. Through better understanding of the large scale dynamic controls, more predictive exploration models have been developed and applied with success to lOCG ore discovery (WMC & BHPB). This presentation provides a comparative global review of the principal lOCG deposit classes, ranging from subvolcanic hydrothermal hematite breccias, through to mid-crustal pyroxenite-hosted magnetite lenses. It demonstrates that most economically-significant lOCG deposits have a magmatic origin and formed in specific rejuvenated paleo back-arc settings, typically lO'-lO^ myrs after subduction termination. The ultimate Cu source resides in domains of sub-backarc metasomatised subcontinental lithospheric mantle, where the metasomatic and partial melt products differ from conventional sub-arc lithospheric mantle. Although both base metal-poor iron-oxide (±P,REE) deposits and lOCG deposits can be hnked to diverse calc-alkahne to alkaline, I- and A-type intrusions, the key factor is mixing volatile- and metal-rich alkaline mafic melts, derived from lowdegree partial mantle melts, with larger volumes of oxidised silicic crustal melts. Under certain conditions, mixing drives Fe-O-S liquid immiscibihty and early C02-rich vapour exsolution. Deep exsolution typically leads to physical separation (<5 km) between hydrothermal lOCG deposits and their parental melts.
Anisotropy of Lithosphere Strength Dave Healy^ Jon Kirby^ Steve Reddy\ Chris Swain^ ^Department of Applied Geology, The Institute for Geoscience Research, Curtin University of Technology, GPO Box U1987 Perth WA 6845 ^Department of Spatial Sciences, The Institute for Geoscience Research, Curtin University of Technology, GPO Box U1987 Perth WA 6845 Recent work using the coherence between gravity and topography reveals a link between azimuthal variations in the flexural rigidity of the Australian continental lithosphere and the fast direction of seismic anisotropy. Flexural rigidity is a
ABSTRACTS alphabetically by surname of presenting author
measure of the elastic response of the Hthosphere to appHed loads. Anisotropy of flexural rigidity has also been reported for the Canadian and Indian cratons. The observed directional dependence of flexural rigidity (elastic response) coupled with the pervasive geological observation of anisotropy in rocks at all scales, prompts us to consider a more general possibility of azimuthal variation in Hthosphere yield strength (elasto-visco-plastic response). Traditionally, the yield strength of the hthosphere has been described with strength profiles derived from laboratory rock deformation experiments. These profiles plot strength (differential stress at yield) versus depth and are constructed for a certain combination of geothermal gradient (or surface heat flow) and constant strain rate. Combining equations for brittle failure (e.g. Mohr-Coulomb) with power law creep leads to 'serrated' curves reflected about the depth axis for tensile and compressive strength; these yield strength envelopes (YSEs) are colloquially known as 'Christmas Trees'. Spatially, these profiles are onedimensional (i.e. depth only, z); there has been no systematic consideration of azimuthal variations in strength in the horizontal plane (jc, y). In this contribution we explore the concept of a fully three-dimensional YSE reflecting azimuthal variations in Hthosphere strength. We combine theoretical models for the failure and flow of anisotropic materials with the sparse experimental data to outline a range of possible shapes for the YSEs appropriate for different continental settings e.g. craton, margin, orogen. Given the limitations inherent in constructing a YSE that accurately describes a specific section of Hthosphere and the complexity due to the many variables already involved (heat flow, strain rate, weakening), the indiscriminate use of previous (one-dimensional) YSEs has been widely criticised in the literature. However, we believe it is important to incorporate azimuthal variations in YSEs to better reflect the growing evidence for directional dependence of Hthosphere response to deformation.
Integrating deep Earth dynamics in paleogeographic reconstructions of Australia. Christian Heine^ l R. Dietmar Mueller^ Bernhard Steinberger^, Lydia DiCaprio^ ^ EarthByte Group, School of Geosciences, The University of Sydney, NSW 2006, Australia (christian® geosci.usyd.edu.au, dietmar@geosci. usyd. edu. au, lydia @gps. caltech. edu) ^Center for Geodynamics, Norges Geologiske Unders0kelse (NGU), Trondheim, Norway (Bernhard.steinberger@ngu.no) Now at.' StaoilHydro, Global Exploration Technology, Oslo, Norway
The Cenozoic flooding history of Australia is characterized by progressive inundation, contradicting the global eustatic sea level fall since the Late Cretaceous. We attribute this unique flooding history to increasing negative dynamic topography with the Australian continent moving towards the SE Asian subduction zone system. By combining plate kinematics with a global mantle convection model, paleogeographic data, eustatic sea level estimates and sediment backstripping, it is possible to reconstruct the Australia flooding history for the last 70 Ma on a continental scale. We use the well-established analytical flow model approach for mantle convection modeling during the Tertiary, based on mande density anomalies derived from the S20RTS shear-wave tomography model. Time-dependent dynamic surface topography is computed from this convection model using a free upper surface, and combined with a global sea level curve to model continental inundation. Sediments in two major Tertiary depocentres, the Murray-Darling and Eucla basins, are backstripped through time to adjust the topographic baseline of the elevation model. We show that a combined eustasy and mantle-driven dynamic topography effect, scaled with a factor that is chosen based on comparison with published geological observations, can successfully predict Australia's changing paleogeography through time and account for regional episodes of subsidence and uplift, whose origin were previously unknown. We find that eustasy and scaled mantle-driven dynamic topography are of similar magnitude for the Late Tertiary in Australia. As first-order sea level dropped due to progressive glaciation, much of Australia was drawn down as it moved towards the southeast Asian slab burial grounds, compensating and partly outpacing the eustatic effect for much of Australia during it's northward motion away from Antarctica. We conclude that understanding the interplay between eustasy and mande-driven dynamic topography is critical for understanding hinterLand uplift, basin subsidence, the formation and destruction of shallow epeiric seas and lakes and their facies distribution.
Imaging the Australian Continental Lithosphere with the National AuScope MT Facility Graham Heinson, Stephan Thiel, Goran Boren School of Earth and EnvironmentalSciences, University of Adelaide, Adelaide SA 5005 (Graham.Heinson@Adelaide.edu.au, Stephan.Thiel@Adelaide.edu.au, Goren.Boren @ Adelaide, edu. au) continued next page... Australian Earth Sciences Convention 2008
131
132 ABSTRACTS atphabetfcally by surname of presenting author
The National Collaborative Research Infrastructure Scheme (NCRIS) funded from 20072011 the AuScope Program for infrastructure development to better understand the "Structure and Evolution of the Australian Continent". A national facility magnetotelluric (MT) equipment and data facility is being established at the University of Adelaide (in close collaboration with Geoscience Australia and the ANU) which will be available to the wider scientific community to address geological problems of scales ranging from lOO's of metres to lOO's of kilometres. The equipment pool, which is under construction, will consist of about 25 broadband (0.001 to 100 seconds period-bandwidth) and up to 40 long-period (1 to 100,000 seconds period-bandwidth) MT land instruments. Broadband instruments use magnetic induction coils, and the bandwidth will typically provide conductivity information in the depth range of 100 m to 50 km. Long-period instruments use fluxgate sensors and have optimal resolution between 5 and 500 km. Thus, a combination of broadband and long-period instruments can yield images of two- and threedimensional conductivity structures from the regolith to the transition zone. We also anticipate making available up to 8 long-period marine MT instruments in collaboration with Flinders University for shallow (-100 m) to deep-water (<5000 m) deployment. Instruments will be available through proposal to AuScope and will typically include some technical training, potentially some field assistance and basic processing of time series to the industrystandard electrical data interchange (edi) format for MT responses. Additionally, legacy data from previous MT surveys across Australia will be archived and made available where possible, either as time-series and/or as processed MT response files in edi format. In this presentation, we will oudine the capabilities of the national MT facility, and examples of the how large-scale MT transect and arrays can be used to image the properties of the Gawler Craton in southern Australia.
State Survey Initiatives: What have we learnt from PACE? Paul Heithersay^ ^PIRSA - Division of Minerals and Energy
The PACE initiative was set in train in 2004 with an initial funding of $15 million for five years. Early success encouraged government to double the investment and extend the programme. Exploration investment in South Australia has increased ten fold between 2003 and 2007, a result achieved by a combination of record commodity prices, one of the world's largest drill-out programmes at Olympic Dam and a considerable upturn in exploration success with a direct contribution from PACE funding particularly through Australian Earth Sciences Convention 2008
drilling collaboration. This theme is now being replicated in other jurisdictions. Other critical themes and some welcome unexpected consequences will also be discussed.
Accretion of a Late Ordovician island arc terrane into the northern Tasmanides and its implications for orogenesis. R.A.Henderson\ B.M. Innes\ C.L. Fergusson^ ^ James Cook University, Townsville QLD 4811 (bob. Henderson @jcu. edu. au) ^University of Wollongong, Wollongong NSW 2522 (cferguss @ MOW. EDUMU) Siluro-Devonian tracts of the northern Tasmanides largely consist of accretionary complex rocks which formed outboard of forearc and arc elements. For the Broken River Province, the accretionary complex consists mostly of poly-deformed turbidites, extensively disrupted by melange, with minor components of MORE - type basalt and chert. However, Late Ordovician volcanics and marine strata form a distinctive terrane located on the inboard margin, the oldest part of the accretionary complex, faulted against pre-Silurian basement and subjacent to an extensive forearc assemblage. This distinctive Late Ordovician terrane includes Everetts Creek Volcanics consisting mainly of basalt and andesite and Carriers Well Formation which is mainly sedimentary in character. The two units show gradational contacts suggesting a close temporal association and Carriers Well limestones are of Late Ordovician (Ashgil) age. Trace element geochemistry shows the volcanics to be of oceanic island arc affinity. The assemblage represents subduction-related volcanism which built relief on ocean crust allowing the development of shallow marine sedimentary facies including carbonate shoals. Strata within the terrane are steeply dipping and generally west facing but some internal folding is indicated by facing reversals. Zones of melange are well represented, and the distribution of limestone as scattered pods and lenses ranging from metre to kilometre scale in length are indicative of internal disruption and zonal shear. We interpret the structural character of the terrane as due largely to subduction accretion. A basement-cover unconformity beneath the subjacent forearc sequence is attributed to Early Silurian (-430 Ma) contraction on the basis of the age assigned to a thick basal conglomerate interval of syntectonic origin. This contractional episode has regional expression in pre-Silurian rocks of the northern Tasman Orogenic Zone. Its likely cause was impact of the Late Ordovician oceanic island arc assemblage against the then continental margin in the initial stage of subduction complex development.
ABSTRACTS alphabetically by surname of presenting author
Experimental Constraints on the Slab Component of Arc Magmas Joerg Hermann^ Daniela Rubatto^ ^ Research School of Earth Sciences, The Australian National University, 0200 ACT (joerg. hermann@anu. edu. au; daniela. rubatto@anu. edu. au Trace elements of arc rocks provide key information on the formation of new crust. In order to understand the general trace element signature of arc lavas, phase and melting relations in metapelites at sub-arc depth are of first order importance. We performed experimental studies on trace element doped, hydrous (2-7 wt.% P^O), synthetic pelite and granite in the range 20-45 kbar and 600-1050°C, i.e conditions relevant for the slab at sub-arc depth. One surprising feature in the lun products is the presence of accessory phases such as rutile, apatite, zircon and allanite/monazite at subsolidus and at suprasolidus conditions, even at large melt proportions of 50%. In the presence of accessory phases, several trace elements are buffered (Ti by rutile, P by apatite, Zr by zircon, LREE by monazite/allanite) whereas K is buffered by residual phengite. This means that the concentration of these elements in the fluid phase is independent of the amount of the phase in the residue (as long as it is present) and independent of the amount of partial melting. However, the concentration is strongly dependent on the temperature and the nature of the fluid phase, and therefore provide excellent constraints on top slab temperatures. The most distinct feature of arc rocks is the addition of a subduction component containing LILE (K) and LREE (Ce). If we consider that in most cases, the subduction component constitutes less than 20% of a primitive arc magma and use for example primitive arc lavas of the Marianas having 5000-8000 ppm K and a subduction contribution of 3-15 ppm of Ce, the minimum concentration in the fluid phase released from the subduction zone must be 25'000-40'000 ppm K and 15-75 ppm Ce. From the experiments it is evident that this is only possible if the fluid phase is a hydrous melt and top slab temperatures are higher than 750°C.
Geological Society of America's Public Policy Programs JohnW. Hess^ ^PO Box 9140, Boulder, CO 80301-9140 (jhess @ geo society, org)
The Geological Society of America's (GSA) Mission and Vision includes "promoting the geosciences in the service of humankind" and "supporting the application of geoscience
knowledge and insight to human needs, aspirations, and stewardship of the Earth" respectively. This is being accomplished in part through a new initiative call the National Leadership Initiative (NLI). The NLI includes a Washington, DC based government affairs office and building strong relations with federal agencies including several public lands agencies. The National Leadership Initiative (NLI) represents GSA and its members on pubhc policy issues and activities, including federal support for the geosciences and the use of science in the decision-making process. The NLI works cooperatively with other societies to meet goals and objectives that reflect those of the GSA community. The NLI is an advocate for and a liaison between the GSA community and Congress, the White House, and federal agencies. The NLI is supported by the Society's Geology and Public Policy Committee and Council approved position statements. The Society with matching support from the U.S. Geological Survey participates in the Association for the Advancement of Science Congressional Science Fellow Program which places a geoscientist in Congress for a year.
A newly discovered meteorite impact crater, Opthalmia Range, Western Australia Arthur Hickman ^ Andrew Glikson^, and John Vickers^ ^Geological Survey of Western Australia, 100 Plain Street, East Perth, l^.A. 6004 ^Department of Earth and Marine Science, Australian National University, Canberra, A.C.T. 0200 A young, morphologically well preserved crater, with a circular rim 260-270 metres in diameter and 20-30 metres high, was recently discovered at 119^41'E, 23°02'S, in the northern part of the Opthalmia Range. Arthur Hickman first recognized the crater-like structure on Google Earth in July 2007, and advised Andrew Glikson. Andrew and John Vickers undertook a field inspection the structure in late August 2007. Evidence supporting a meteorite impact origin includes the presence of a distinct raised rim with steep inner slopes and shallow outer slopes. The crater lies on a conformable contact between Paleoproterozoic Woongarra Rhyolite and Boolgeeda Formation (banded iron-formation). The banded iron formation is extensively brecciated, and the rhyolite is penetratively fractured in the rim. The rhyolite is injected by a penetrative system of iron-rich veins accompanied by sharply defined alteration zones containing dark veins of carbon-bearing iron-rich cryptocrystalline material, possibly derived from explosive vaporization of a meteorite or, alternatively, from shock-melting of banded iron formation. Blocks of veined and deformed rhyolite breccia rest on
continued next page... iences Convention 2008
133
134 ABSTRACTS alphabetically by surname of presenting author
undeformed country rocks up to 300 metres from the crater. Other features suggestive of impact deformation include shatter fracturing of the rhyolite and banded iron-formation, and incipient intracrystaUine dislocations in quartz. As the crater is superposed on, and bars, the local drainage system, its age is estimated at less than 100,000 years. Alternative origins for the structure are not supported by available evidence. For example, a diatreme origin is considered highly improbable because only rhyolite and banded iron-formation are exposed in crater rim, and because aeromagnetic data provide no evidence of other rock types within the structure. In recognition of its first identification, Andrew Glikson has proposed that the crater be given the structural name Hickman Impact Crater.
An overview of four international geoscientific drilling projects, Pilbara Craton, Western Australia, 2003-2007 Arthur Hickman^
^Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia Between June 2003 and August 2007 four international collaborative geoscientific drilling projects were conducted in the Pilbara region of Western Australia, with cooperation and assistance from the Geological Survey of Western Australia (GSWA). Seven organizations from the USA, Japan, France, and Australia undertook the drilling: in 2003-2004, the Pennsylvania State Astrobiology Research Center (PSARC), Kagoshima University (KU), and the University of Western Australia (UWA); in 2004, Arizona State University (ASU), the University of Washington (UW), and the Institute de Physique du Globe de Paris (IPGP); and in 2007, Kyushu University (KYU). In total, fourteen holes were drilled to depths generally between 100 and 300 metres (the deepest hole was 960 metres) through formations ranging in age from 3.48 to 2.49 Ga. This diamond core drilling has provided continuous sections through carbonaceous and sulfidic shale (marine and freshwater), stromatolitic limestone (shallow marine or lacustrine), dolostone, chert, and iron formation (deep water), and basalt (deep water to subaerial). Additionally, one hole intersected a weathering horizon immediately beneath a 3.43 Ga Archean erosional unconformity. The research has been primarily geochemical, aimed at obtaining uncontaminated evidence on the changing nature of the Archaen biosphere and atmosphere over 1000 million years. Techniques employed have included microscopy (optical. X-ray chemical, transmission electron, and scanning electron). Laser Raman spectroscopy, geochronology, and fluid inclusion analysis. With numerous researchers involved, and the range of methods being applied, results and Australian Earth Sciences
Convention 2008
interpretations have varied. PSARC, ASU, and UW found compelling evidence that the Earth's atmosphere was not entirely anoxic in the Neoarchean, and PSARC found evidence that oxygen was present as early as 3.46 Ga. IPGP obtained petrographic and sulfur isotope data interpreted by GSWA to support previous interpretations (based mainly on morphology) that stromatolite-like structures as old as 3.48 Ga are biogenic, and not merely products of abiological chemical precipitation processes.
Geosyntax: A New Computing Language for Geology Data June mi\\ Cedric Griffiths^ ^ CSIRO Petroleum, 26 Dick Perry Ave, Kensington, WA 6151, Australia. (June.Hill@csiro.au Cedric. Griffiths @ csiro. au) The storage and manipulation of hard data on computers is a straightforward process. However, the process of digitisation of soft geological data is more problematic. By soft data we can include such items as the distribution of shapes and sizes of geological entities and the relative spatial arrangement of entities. We are developing a new method that will allow digitisation of such soft data as a geological language. Formal languages are specified by a grammar. The grammar incorporates a set of words (vocabulary) and a set of rules that describe how to construct valid sentences from the vocabulary. We are constructing geological grammars to represent different geological environments. Each grammar contains a set of geometric symbols (the vocabulary) that are used to represent all the geological entities in the environment. The symbols have attributes, these may be deterministic, such as facies type (e.g. channel fill), or probabilistic, such as a measurement of the entity (e.g. the parameters of a log-normal distribution for channel width). Each grammar has as set of rules which describe the valid arrangements of the geological entities; for example, that channel levee deposits should lie either side of channel fill deposits. Our vision is that when geologists are mapping a region, they would collect soft data (as well as hard data) in a consistent format that will form a new geological language. Digitised descriptions of several similar geological regions can be coalesced to derive a generalised grammar; for example a grammar which describes the typical deposits of any meandering river system. Currently we are working on developing grammars for sedimentary environments. We are also developing a program (a parser) that will be capable of using the grammars to generate examples of 3D geological models from a specified environment.
ABSTRACTS alphabetically by surname of presenting author
A Regolith and Landscape Evolution Framework for Mineral Exploration Under Cover in the Northern Flinders Ranges - Frome Embayment, South Australia
Predicting hydrological threshold events in response to climate.
S.M.Hiir
^ School of Earth and Geographical Sciences, The University of Western Australia, M087, 35 Stirling Highway, Crawley, 6009, Australia (christoph. hinz@uwa. edu. au)
'CRC LEME, School of Earth & Environmental Sciences, University of Adelaide, SA 5005 (steven.hill@adelaide. edu.au) The regolith and landscape evolution constrain the expression of bedrock-hosted and the development and expression of palaeodrainage hosted uranium mineralisation in the northern Flinders Ranges - Frome Embayment area of South Australia. Regolith and palaeo-landscape associated with the Mesozoic, Eromanga Basin include the palaeodrainage (fluvial and minor glacial) transport of uranium-rich detritus within a landscape of moderate topographic relief and variable bedrock exposure. Cretaceous marine transgressions extended across low-lying parts of the landscape and deposited chemically reduced clays and silts, which have potential to be important chemical traps for uranium. The Mesozoic sediments have since been tectonically disrupted, particularly during the Neogene. Cainozoic regolith and landscape evolution is associated with the Lake Eyre Basin and hinterland development. Palaeogene fluvial deposits associated with the Eyre Formation have been important hosts for uranium mineralisation at sites such as Four Mile Creek and Honeymoon. The landscape at this time hosted highly weathered Mesozoic sediments and hmited bedrock exposure. Pedogenic silcrete development was extensive in the later stages of Eyre Formation sedimentation, and was followed by fluvial and lacustrine sedimentation of the namba Formation. Redox-fronts in the Namba Formation have been important for the development of uranium mineralisation at Beverley. Ephemeral fluvial, lacustrine, colluvial and aeolian deposition as well as tectonism and pedogenisis have been spatially and temporally variable in the more recent geological evolution. The regolith and landscape context has provided an important framework for regolith geochemical and biogeochemical studies that characterise the surficial expression of buried uranium mineralisation. This has included soil, palaeosediment, contemporary stream sediment, regolith carbonate, vegetation, ant and macropod scat samples.
Christoph Umz\ Gavan S. McGrath^ Amy J. Hearman^
Many hydrological processes such as runoff, preferential flow, erosion, and trace gas emissions amongst others are episodic and controlled by soil/rainfall thresholds. The goal of this paper is to analyse the temporal structure of such threshold events based on the statistical properties of rainfall and a simple conceptualisation of such thresholds. A probabilistic framework has been derived to assess the likelihood of thresholds events to occur. We distinguish between intensity thresholds such as a rainfall intensity that causes infiltration excess overland flow and a storage threshold such as a critical soil water content that triggers saturation excess overland flow or nitrous oxide emissions. Based on the assumption that the time in between storms are random and therefore following a Poisson distribution, we estimate the statistical properties of the time between hydrological threshold events. For intensity thresholds it is shown that the statistical structure of rainfall is preserved meaning that the time in between intensity threshold events are also randomly distributed but less frequent then the storms. This is very different for storage thresholds, for which the statistical structure changes from random to clustered behaviour. The clustering is caused by a memory effect of for example slowly changing soil water content. We compared the storage threshold behaviour for different climatic situations from hyper-arid to strongly humid situations. We found that the variability of the storage threshold triggering is greatest for semi-arid climates where evaporative demand is in the same order of magnitude as precipitation. The variability decreases for more arid and more humid climates which has very important implications for predicting impacts of climate change. The variability of hydrological threshold events will be most strongly affected by changes in semi-arid climate regions and hence may have severe effects on pulsed ecosystems. The theoretical finding have been backed up and applied to pesticide leaching by preferential flow, nitrous oxide emissions from soil and surface runoff for which examples will be presented.
Australian Earth Sciences Convention 2008
135
136 ABSTRACTS alphabeticaliy by surname of presenting author
Cyclicity in Late Devonian conglomerates, Lennard Shelf, Canning Basin, W. A.
Vines 1 revisited: Neoproterozoic successions in Western Australia.
Roger Hocking^ and Phillip E. Playford^
Peter W Haines ^ Roger Hocking \ and Kathleen Grey^
^ Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia froger. hocking(a\doir. wa. gov, au)
^ Geological Survey of Western Australia, 100 Plain Street, East Perth WA 6004, Australia, (roger. hocking@doir. wa.gov. au)
Conglomerates associated with Devonian reef complexes along the northern margin of the Canning Basin in northern Western Australia in places show marked metre-scale cyclicity. Cycles are characterized by the presence of cobble to boulder conglomerate, but also contain sandstone, fmer conglomerate, and bioclastic limestone. Cycles can be related to metre-scale cycles recorded in
Vines 1 is a 2017.5 m deep, fully cored stratigraphic hole drilled by the Geological Survey of Western Australia in 2001 near the Western Australian - South Australian border. The succession in Vines 1 was initially thought to be a single conformable stratigraphic package of Cambrian age, the Vines Formation, and could not be readily correlated with other successions in the Centralian Superbasin. It is now reinterpreted as four discrete sedimentary packages. Palynomorphs recovered throughout the hole and previously used to infer an age of no older than earliest Cambrian are now thought to be contaminants, but an older assemblage, interpreted as reworked from underlying rocks, provides a new maximum age constraint of mid-Neoproterozoic. Sedimentological interpretations of the four packages now recognized in Vines 1, and comparisons with other drillholes in the western Officer Basin, and the successions in the eastern Officer Basin and central Amadeus Basin, invite correlation with glacial successions in Supersequences 2 and 3 (mid to late Cryogenian) of the Centralian Superbasin equivalent units in the Adelaide Rift Complex of South Australia (packages 1 and 2, Pirrilyungka and Wahlgu Formations), eolian successions interpreted as Supersequence 4 in the western Officer Basin (package 3, Lungkarta Formation), and probable latest Neoproterozoic earliest Cambrian fluvial units of the Amadeus Basin and western Officer Basin (package 4, Vines Formation). Vines 1 can thus be regarded as a link between the western Officer Basin and the Neoproterozoic of South Australia and the Northern Territory. Older Neoproterozoic glacial deposits are now recorded in WA, and in Vines 1 may link to the uppermost Buldya Group (Supersequence 1), although it may not be possible to confirm this link from available data. Facies belts appear to be very broad and climate driven. Eolian deposits extend more than 800 km from outcrop in the northwestern Officer Basin, near Lake Disappointment, to the WA-SA border. Fluvial deposits above are similar in colour and facies in Vines 1, the Durba Sandstone of the northwest Officer Basin, and the Ammbera Sandstone of the Amadeus Basin.
correlative carbonate platforms, and in places are
transitional into such cycles. In the Sparke Range (SE Lennard Shelf) conglomeratic cycles are present in two fault compartments, each floored by a basal tectonic glide plane, within a thick, extensive conglomerate body that was deposited in both platform and basinal settings. Cycles average about 12 thick, and the cyclic interval spans about 1800 m deposited thickness. They shallow upwards, from subaqueous bases locally with bioturbated, sub-wavebase sandstone to shallow subaqueous or subaerial boulder conglomerate. Some have platform carbonate intercalations, and boulders of reworked reefal limestone are scattered throughout the section. No regular pattern or trend of clast composition can be recognized up the section. The cycles are entirely Late Frasnian in age. The periodicity of the cyclicity can be estimated by comparison with a nearby section of Late Frasnian platform, where metre-scale platform cycles have a calculated duration of 15 000 to 20 000 years. This suggests orbital forcing as a climatic control on the cyclicity. Around Mt Elma (NE Lennard Shelf), Late Frasnian and possibly Early Famennian cycles can be discerned where ephemeral patch reefs have developed on the sides of a large alluvial fan to fan delta conglomerate body. Counter-intuitively, the cycles consist of subaqueous conglomerate at the base, capped by shallow back-reef carbonates extending laterally from patch reef cores. The cycles are the same scale as those in Sparke Range, but the limestone caps to the cycles suggest a climatic control. Conglomerate influx must have waned to stopped on a regular basis, to allow shallow water limestones to develop. Laterally and slightly higher stratigraphically, conglomerates fme to sandstone and eventually siltstone and interfmger with backreef limestones. Fenestral desiccation polygons indicate the limestones cap the cycles.
ABSTRACTS alphabetically by surname of presenting author
Automated Polished Slab Image Analysis for Olivine Crystal Size Distribution Detection Eun-Jung Holden^ Mike Dentith\ Stephen Moss^, Kelly Russell^ ^ Centre for Exploration Targeting, The University ofWA, Crawley, WA (eiiniungCcv-cyUene, uwa. edu. an: mdentithCdlcvllene. uwa. edu. aid Mineral Deposit Research Unit, University of British Columbia, Vancouver, B.C., Canada (kriissellCdleos. iibc. ca: smoss@eosMbc.ca) This paper presents on-going research in automatically characterising olivine crystal size distributions (CSD) using polished slabs. Olivine crystal size distributions in kimberlite rocks are useful with respect to two aspects of kimberlite geology. 1) the characteristics of the diamond population can be estimated using olivine as a proxy. 2) the nature of the eruptive mechanism can be studied through comparison of olivines in kimberlite magma (un-erupted) with those in pyroclastic (erupted) kimberlite to determine how much the solid particles in the magma break up during the volcanic eruption. Olivine crystals are automatically identified b y a combination of nmltiple image cues such as brightness, shape, colour, and texture. This detection process uses grayscale foreground object segmentation combined with solid shape detection, texture analysis using standard deviation of pixel intensities in local neighbourhood, and model-based colour detection using the Mahalanobis distance measure. This resulted in some closely located crystals being detected as a single object. These joined objects are then segmented using an extended watershed algorithm to separate objects of varying sizes. The result of the automatic detection has been compared with manual detection. Approximately 80% of the manually detected olivine regions are detected automatically and 93% of the regions that are automatically detected correspond to the manually detected regions. This comparable result was achieved in less than a minute, whilst manual analysis took several hours.
Interpretation of Aeromagnetic Datasets for Gold and Diamond Exploration: An Image-Analysis Approach Eun-Jung Holden\ Mike Dentith^ ^ Centre for Exploration Targeting, The University ofWA, Crawley, WA (eunjim^CdlcvUene. uwa.edu.au: mdentith@cylleneMwa.edu.au) Automated analysis of digital imagery is a
mature discipline with applications in fields as diverse as surveillance, medicine and robotics. However, its use in the analysis of geoscientific datasets is in its infancy. The general availability of cheap regional-scale aeromagnetic datasets suggests their use for prospectivity analysis, in particular ground selection, during mineral exploration. The large size of the datasets requires a degree of automation. On-going research in the Centre for Exploration Targeting at UWA has led to the development of algorithms that seek to identify characteristics of aeromagnetic datasets that are considered to be of exploration significance. For example, responses coinciding with areas of structural complexity adjacent to major structural discontinuities are sought during exploration for Archean lode-gold. In diamond exploration discrete responses potentially due to kimberlites are sought. Techniques applied to date include quantification of data symmetry, entropy and the number and orientation of linears. By combining parameters representative of geologically favourable sites, the prospectivity of a region can be rapidly assessed for a variety of deposit types.
The Prohibition Gold Deposit (Murchison, Western Australia), A BIF Hosted Lode Gold Deposit With a Protracted Fluid-Rock Interaction History. Hollingsworth. D.lThebaud. N. ^Center for Exploration and Targeting, UWA, 35 Stirling Highway, Crawley, WA 6009 (nthebaud@cyllene. uwa. edu.au) ^Mercator Gold Australia Pty Ltd., Applecross, WA 6153 (david.hollingsworth@mercatorgold.com.au) The Prohibition deposit lies in the central part of the Paddy's Flat mining district, in the northern part of the Murchison goldfield, Yilgarn Craton. Exploited by both underground and open pit mining for over 100 years, the Prohibition deposit has produced -140,000 oz of gold. The current indicated resource for the Prohibition area stands at 2.5 Mt @ 4.0 g/t for 320,000 oz. The Prohibition deposit is hosted by an ironrich chert / BIF horizon within a sequence of pyroclastic sediments and basalt flows. The sequence has been folded and faulted during complex continuous deformation most likely associated with granitoid emplacement at around 2.7Ga. The mineralisation at Prohibition is associated with a set of westerly dipping faults. Where the faults intersect the iron-rich chert or BIF unit, brittle fracturing and mineralisation is widely developed. The gold related alteration is associated with quartz - chlorite - sulphides +/- feldspar and continued next page.. Australian Earth Sciences Convention 2008
137
138 ABSTRACTS alphabeticaity by surname of presenting author
carbonate mineral assemblage. Intense sulphidation of magnetite rich bands within the BIF is common within mineralised zones and represents up to - 4 0 % vol. of the rock in places. The dominant sulphide phase is pyrite but significant amounts of arsenopyrite (or lollingite) have been documented. In microscopic view, both populations coexist as separate mineral phases. Pyrite commonly displays inclusions of gold, arsenopyrite and gersdorffite (NiAsS). Fluid sources and detailed characteristics remain uncertain at this stage, however microtextural observation conducted during this study suggest that mineralisation resulted from the introduction of at least one fluid phase rich in Au, S, As and K +/- Si02.
Tectonic Controls on the Sequence Stratigraphic Architecture in a Nonmarine Rift-basin Setting: An Example from the Tertiary Bohai Bay, East China.
Formation shows a characteristic "triple-section" facies combination in their wireline (SP) log signatures from bathyal, abyssal lake to deltaic facies with reservoir quality increasing gradually from SQ5 to SQ7. On the basis of the different characteristics of cores, wireline log responses and seismic data, the seven stratigraphic sequences can be correlated consistently throughout the entire basin. The stratigraphic and sedimentary model developed for the Shahejie and the Dongying formations is believed to be strongly controlled by the tectonic evolution of the rift basin and may have important implications to basins with similar tectonic setting elsewhere.
New Insights into Landscape Evolution of the Eucla Basin and Palaeochannels, Southern Australia B. H o u \ L.A. F r a k e s ^ M . S a n d i f o r d ^ L. W o r r a l l ^ J. K e e l i n g ^ & N . F . A l l e y ^
H o n g t a o Z W ' ^ , K e y u Liu^, Y u a n s h e n g Du^ ^ Faculty of Earth Resources, China University of Geoscience, Wuhan 430074, China. Zhuht_oscar@yahoo. com. cn ^ CSIRO Petroleum Resources, P.O. Box 1130, Bentley, W.A. 6102, Australia. Keyu.liu@csiro.au ^ Faculty of Earth Science, China University of Geoscience, Wuhan 430074, China. dxyyz@cug. edu. cn The Bohai Bay region, east China has been actively explored for hydrocarbons for the last four decades. With the recent new discovery of the Giant Nanpu Oildfield with an estimated 3P reserve of over one billion tonnes a renewed exploration interest has been sparked in the region. The main reservoirs in the Bohai Bay Basin are the Tertiary Shahejie and Dongying formations, which comprise seven third-order sequences (SQ1~SQ7) from base to top. These sequences were developed in response to different tectonic stages of the basin evolution from an intensive rifting to a late stage of rifting. They represent a second-order tectonic sequence. The lower four third-order sequences (SQ1~SQ4) of the Shahejie Formation, developed during the intensive rifting to the stable rifting stage, form the ascending half-cycle of the second-order sequence. The top three third-order sequences (SQ5~SQ7) of the Dongying Formation developed during the atrophy stage of the rift basin, form the descending half-cycle of the second-order sequence. The Shahejie Formation consists of stacking sequences with a distinct "four-part" facies combination on the wireline (SP) log responses from deltaic, gravity-flow, bathyal to abyssal lake deposits from base to top with an overall relatively poor reservoir quality. In contrast, the Dongying Australian Earth Sciences Conventton 2008
^CRC LEME, Primary Industries and Resources SA, GPO Box 1671, SA 5001, Australia (hou. baohong @ saugov. sa. gov.au) ^The University of Adelaide, Adelaide, South Australia, 5005, Australia (larry.frakes @ adelaide. edu.au) ^School of Earth Sciences, University of Melbourne, Victoria, Australia (mikes@unimelb.edu.au) "^CRCEEME, Geoscience Australia, GPO Box 378, Canberra Act 2601, Australia (Lisa. Worrall @ ga. gov. au) ^Monax Mining & Marmota Energy, llA Croydon Road, Keswick SA 5035, Australia (nalley @ monaxmining. com. au) The Eucla Basin lies on the margins of the Yilgarn, Musgrave and Gawler cratons in southern Australia and owes its distinctive landscape to a unique set of interactions between eustatic, climatic and tectonic processes over the last - 5 0 Ma. Understanding of the history of the basin and the palaeovalleys that drained from the surrounding cratons is important because the cratons contain significant mineral and groundwater resources, including commodities such as gold, uranium and heavy minerals that have been reworked and concentrated within the sediment cover. In particular, a remarkably preserved palaeoshoreline sequence along the north-eastern margin of the Eucla Basin is highly prospective for heavy mineral deposits. The record of marine, marginal marine, estuarine, fluvial and lacustrine environments, as constrained mainly by an extensive borehole dataset, reflects major depositional events during Cainozoic. These events reflect the key role of eustatic sea-level variation which, during high stands, inundated the craton margins, flooding palaeovalleys to up to 400 km inboard of the present
ABSTRACTS alphabetically by surname of presenting author
coastline. However, a systematic eastward migration of the depocentre across the Eucla Basin during the Neogene, together with apparent flow reversals in a number of palaeovalley systems draining the Gawler Craton, suggests that the Eucla Basin has also been subject to differential vertical movements, expressed as a west-side up, east-side down tilting of -100-200 m. This differential movement forms part of a broader north-down - southwest-up dynamic topographic tilting of the Australian continent associated with relatively fast (6-7 cm/yr) northward plate motion since fast spreading commenced in the Southern Ocean at -43 Ma. We suggest that the evolving dynamic topography field has played a key role in facilitating development of placer deposits, largely through multistage, eastward reworking of near-shore sequences during highstand transgressive cycles on a progressively tilting platform under the influence of persistent westerly weather systems.
Predictive Modeling of gold deposits; Walhalla - Woods Point region, Eastern Victoria Megan Hough^ Laurent Ailleres\ Frank Bierlein^, Sean Sivasamy^ Stuart Hutchin^' Nick Thorp^ ^ School of Geosciences, Monash University VIC 3800 (Megan.Hough @ sci. monash. edu. au) Centre for Exploration Targeting, University of Western Australia VKA 6000 ^ Goldstar Resources, Rawson VIC 3825 The Walhalla-Woods Point Goldfield (>80 t Au produced) in eastern Victoria, hosts anomously large deposits, in comparison to similar-aged goldfields in the easternmost Western Lachlan Orogen. The ten highest yielding deposits are either hosted within, or spatially associated with, intrusions of the Devonian Woods Point Dyke Swarm. To understand the controls on mineralisation throughout the historically important goldfield, comparisons were made between a number of gold deposits; primarily the sediment-hosted, dykeassociated Cohen's Reef, and the dyke-hosted Eureka and Tubal Cain deposits near the historical township of Walhalla, It has been previously established (F. P. Bierlein et al., 2001, Lithos, v.58, p.l) that the individual dyke units are favourable hosts for gold mineralization due to their Fe-rich geochemistry and brittle response to deformation. In addition, the dyke swarm is favorably located in close proximity to the terrane boundary fault zone between the Western and Central Lachlan Orogens. This research has incorporated 3D modeling of recent and historical data, along with geochemical and petrological studies to estabhsh local and regional controls on the siting and grade of the gold deposits, including the role of competency contrast between the Devonian meta-sedimentary host rocks
and dykes, and the role of the varying petrology of the dyke swarm. This research has also incorporated FLAC 3D mechanical and fluid-flow modeling of the region to establish the role of the changing tectonic regime on the formation of dyke bulges, the formation and orientation of gold reef-hosting reverse faults, and the controls on the numerous hydrothermal events which formed the sequence of laminated veins and later brecciated veins with higher gold grades. Predictive modeling of the Walhalla-Woods Point region in regards to the controls on the siting of gold mineralization, will also establish the evolution of compressional to transpressional stress regimes in terms of the final amalgamation of the Lachlan Orogen.
A New View of Hypogene and Supergene Gold: Clues for Ore Paragenesis and Exploration Robert Hough\ Charles Butt^ Steven Reddy^ Martin Saunders^ Peta Clode^, Chris Ryan\ Ryan Noble\ David Belton^ ^CSIRO Exploration and Mining (CRCLEME), PO BOX 1130, Bentley, Perth. (Robert.hough@csiro.au) ^Institute of Geoscience Research, Curtin University of Technology, Perth. Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley, Perth. In studying the critical elements of ore fluid history in a gold deposit, the transport, timing, deposition, and mineral associations of gold itself are pivotal to any interpretation. Gold is, however, a relatively poorly studied component of such deposits, probably because it is often considered refractory and rarely free without genuine attempts to isolate and analyse it in detail being made. New developments in geochemical analysis for gold (LA-ICPMS, PIXE, SXRF) and high magnification electron microscopy are providing new data and images of the distribution of submicron gold in both hypogene and supergene samples. This is enabhng us to image considerd gold in systems such as calcrete, gossans, laterite gravels and hypogene ore veins, previously considered 'invisible'. Here the gold has been found to be particulate and crystalline in its form and distribution at all scales. By considering crystallography and composition, recent work on gold nuggets has shown that they are hypogene in origin. This includes nuggets found on salt lakes where the main mass may display an external surface coated in pure supergene gold but the core still comprises the primary hypogene Au/Ag alloy. Single crystal nanoparticles and nanoplates of pure colloidal supergene gold have been found continued next page.. Australian Earth Sciences Convention 2008
139
140
ABSTRACTS alphafoeticaily by surname of presenting author
precipitating through an evaporative process from southern Yilgarn sahne waters, providing the first direct evidence for the existence of colloidal gold transport during weathering, a long inferred process. Our results and approach suggest that all gold should be treated as crystalline. Considering crystal structure together with composition provides a new insight into gold paragenesis in all environments. Gold is the critical component of gold deposits, supergene or hypogene, and is yet to reveal its complete thermal, chemical and mechanical history.
of with
Geochemical and Nd Isotopic Signatures of Mafic Dykes in the Western Musgrave Complex
Dennis Arne^ and Jon
H. M. Howard\ R. H. Smithies^ and P. M. Evins^
Hyperspectral Interpretation Alteration Haloes Associated Victorian Orogenic Gold Deposits Emily House\ Huntington^
low levels of ferroan carbonate (generally much less than 20%) using the VNIR and SWIR data has proved difficult. A semi-quantitative measure of the Fe carbonate content was achieved by matching spectra against a custom spectral library of Fe carbonate samples. The resulting values correlate well with elemental CO2. Improvement in carbonate detection is also being addressed by looking in the thermal infrared wavelength region with the new TIR-Logger.
^ GeoScience Victoria, GPO Box 4440, Melbourne, VIC, 3001 (Emily, house @ dpi, vie, sov.au, Dennis.arne @ dpi. vie. gov. au). ^ CSIRO Exploration and Mining, PO Box 136, North Ryde, NSW, 1670 (ion.huntinston @ esiro.au). GeoScience Victoria (GSV) has recently assessed the application of proximal hyperspectral mineral mapping methods to identify alteration associated with orogenic gold deposits in central Victoria. The aim of the study was to identify any consistent trends in alteration mineralogy or mineral chemistry as gold deposits are approached, usmg hyperspectral techniques such as HyChips . Hyperspectral measurements of drill core samples from Bendigo, Ballarat, Casdemaine, Costerfield, Fosterville, Maldon and Wildwood were taken using a HyChips™ logger. A more detailed assessment of this approach is also in progress following continuous scanning of several drill cores in a recent HyLogging™ trial by GSV and CSIRO. Preliminary results show a distal white mica + chlorite + carbonate alteration assemblage and a more proximal white mica + carbonate alteration assemblage around most deposits. This is in agreement with findings from XRD data presented by Beirlein et al (2000, Economic Geology v.95, pp.283-312) that there is negative correlation between chlorite and ferroan carbonate around several central Victorian gold deposits. More significandy, the position of the main AlOH absorption peak associated with micas shows greater variability and shifts toward lower wavelengths (more 'muscovitic' composidons) within at least 50m of mineralisation at most deposits. A major goal of the trial was to idendfy and quandfy the spectral response of carbonates, as these define the broadest alteration haloes and are potentially the most useful when exploring for similar deposits under cover. However, quantifying Australian Earth Sciences Convent!
^ Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia (heather. howard@doir. wa. gov. au) Six geochemical suites of mafic dykes intrude the Mesoproterozoic rocks of the Musgrave Complex, central Australia. The oldest (c. 1170 Ma) intruded during the Musgravian Orogeny. The Alcurra dykes form part of the 1070 Ma Giles Event and, with associated mafic-ultramafic layered intrusions, form part of the Warakurna large igneous province. Several suites of post-Giles dykes include an un-named plagioclase-rich suite, the Kullal dykes (c. 1000 Ma), the Gairdner Dyke Swarm and Amata Dolerite (c. 800 Ma) and un-named LREE-depleted dykes (c. 750 Ma). Geochemical comparisons show that the dyke suites generally become more depleted in LREE (and other incompatible trace elements) with dme and that the involvement of a crustal component in the magmas decreases. The c. 1170 Ma and Alcurra dykes are strongly LREE-enriched (La/Sm = 4.1 to 4.5, and 2.6 to 3.3 respectively). They have the least radiogenic Nd-isotopic signatures, with epsilon Nd values of -2.42 to -6.20 and +0.89 to -0.92, respecdvely, and show significant negadve Nbanomalies on mantle-normalised plots. They were possibly generated from an enriched source, but were clearly contaminated by continental crust. The dykes of the Kullal Suite and Gairdner Dyke Swarm are only slighdy LREE-enriched and have epsilon Nd values ranging from +0.65 to -2.84 and +2.39 to +3.81, respecdvely. The un-named c. 750 Ma suite are LREE-depleted, have epsilon Nd values of +4.58 to +4.60, no significant Nb-anomaly but low mandenormalised Nb/La (-0.4) and La/Zr (-0.8) rados, suggesting they were derived from a source more depleted than MORE-source, and underwent minimal contamination by crust. Whilst there are secular changes towards incompatible trace element ratios reflecting progressively less-enriched magmas, and to higher epsilon Nd with decreasing age, there is no
ABSTRACTS alphabetically by surname of presenting author
systematic relationship between La/Nb ratios and epsilon Nd. These trends cannot simply relate to reduced crustal involvement. Mantle source enrichment, crustal assimilation, progressive source depletion or asthenospheric replenishment must all be considered.
U-Pb, Nd and Hf isotopic constraints on basin development and deformation in the Western Gawler Craton Katherine Howard\ Martin Hand\ Karin Barovich\ Elena Belousova^, Ben Wade^ ^ Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia (katherine. e. howard@adelaide. edu. au) ^ GEMOC Department of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia The Fowler Domain in the western Gawler Craton is of interest to the minerals industry due to perceived similarities in structure and lithologies with the Thompson Nickel Belt of Canada. Due to the paucity of outcrop, the tectonic history of the Fowler Domain is largely unknown. Some models suggest it records the oblique Palaeoproterozoic collision between the Mawson continent and the Yilgarn Craton via a southeastdipping subduction system. Other workers consider the crustal-scale near vertical shear zones to be evidence of a strike-slip dominated regime. Although these models attempt to explain the macroscopic location and deformation style within the Fowler Domain, there is little basic geological data to constrain the timing of deposition and metamorphism within the individual shear zone bounded domains. This study presents LA-ICPMS U-Pb age data, MC-ICPMS and Nd isotopic data from metasedimentary units intersected in drill core in the central and northeastern Fowler Belt. U-Pb data from a number of detrital zircon samples in the central region provide maximum depositional ages between 1780 and 1700 Ma, with rare older detrital components. In the bulk of samples, £Nd(i700Ma) values range between -4 to -2. The combination of these data suggests evolved and restricted aged source regions. The northeastern Fowler Belt contains Archaean and early Palaeoproterozoic domains which give SNd(2500Ma) values between -4 and 0. Hf isotopic data from the 1700 Ma zircons provides a wide range of values (cefdvooMa) +6 to -6) indicating derivation from a mixture of mantle and crustal material. Monazites from transitional granulite-grade metasedimentary rocks yield metamorphic ages of 1690 to 1670 Ma. The timing of basin development and metamorphism coincides with that of the northern
and eastern Gawler Craton, suggestmg the Fowler Domain may have originally formed part of a large c. 1750-1730 Ma basin system in the southern Australian Proterozoic.
Analysis and Classification of Cosmic Spherules from Lewis Cliff, Antarctica Simeon S. M. Hui\ Marc D. Norman\ Ralph P. Harvey^ Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia ^ Department of Geological Sciences, Case Western Reserve University, Cleveland, Ohio, USA A micrometeorite is an extraterrestrial particle less than 1mm in size and is found on Earth in the deep sea, sediments, swamps and more recendy the ices of Antarctica. About 30,000 tons per year of micrometeorites are estimated to enter the Earth's atmosphere and may be altered by frictional heating while passing through the atmosphere. We have separated, described and classified 120 cosmic spherules, a specific type of micrometeorite, from aeolian sediments at the Lewis Cliff Ice Tongue, Antarctica. This increases the number of previously studied spherules from this locality by about a factor of four. Major element compositional data was obtained using energydispersive and wavelength-dispersive electron microscopy while traces element compositions were obtained using laser ablation inductively coupled mass spectrometry. Cosmic spherules provide insights into the past and present meteoritic bombardment of Earth. It may also be possible to trace them back to their parent bodies. Similarities in petrography and major element chemistry among cosmic spherule collections from diverse localities around the Earth suggest a consistent source supplying the spherules, and analogous processes acting on the spherules during their entry through the atmosphere. The major and trace element data suggests that the majority of the cosmic spherules derive from material similar in chemistry to chondrites, leaning towards CM (carbonaceous) or H (ordinary) type chondrites in particular. Our data also suggest that the controversial iron oxide rich cosmic spherules can be formed by metal/silicate immiscibility, oxidation and fractionation of a common precursor. Enrichment of siderophile elements in iron oxide spherules coupled with complementary depletion in the silicate spherules, the residual, is strong evidence for this process. It is likely that heat alteration and oxidation during atmospheric entry is responsible for the variety of textures and chemistries seen in most cosmic spherules in our collections and possibly in other collections as well.
Australian Earth Sciences Convention 2008
141
142
ABSTRACTS aiphabetically by surname of presenting author
The AuScope National Virtual Core Library - Development of a New National Pre-Competitive Data Set
Constraints on the genesis of the Nolans Bore REE-P-U-Th deposit, Northern Territory, Australia.
Jon Huntington \ Mason^ Lew Woodcock^
Kelvin Hussey^ Goulevitch^
Peter Warren\ Peter Whitbourn\ Robert
^ CSIRO Exploration and Mining, PO Box 136 North Ryde NSW 1670, Australia, ^ CSIRO Exploration and Mining, 26 Dick Perry Ave, Kensington, WA 6151, Australia In a major new national collaboration each of the State and Territory Geological Surveys, CSIRO, AuScope and the Federal Government will be deploying to each jurisdiction in 2008 a suite of technologies for the hyperspectral scanning of drill cores held in the many public core libraries around Austraha. The project, extending to at least 2011, will gradually build-up a unique database of new mineralogical information products and core images to be served to the research and user communities via the Web. Based on CSIRO's HyLogging™ concept, the project involves the construction of seven new generation HyLogger-2 core scanners, their deployment to each jurisdiction, their operation by the State and Territory Geological Surveys to scan high priority cores, the creation of useful information products, and the publication of these via the Internet through a common AuScope-Grid portal. The initial data will cover visible and shortwave infrared wavelengths sensitive to oxides, hydroxide-bearing clays and phyllosihcates, sulphates and carbonates. Via a second iteration, addition of a thermal infrared sensor, sensitive to feldspars, quartz, olivines, pyroxenes and garnets, as well as a range of other minerals, it is hoped to create a truly unique dataset characterising the top 1-2 kilometres of type areas of the Australian continent. This database will in turn facilitate multidisciplinary research across the whole earth science community, as well as contribute to the development of the AuScope Earth Model, a live, on-line, four dimensional model of the Austrahan continent. The paper provides insight into the project's goals, examples from a variety of States of data already collected through the AuScope NVCL Precursor Program, and a glimpse of future information products, web-based services and downstream research opportunities.
Australian Earth Sciences Convention 2008
David
Huston^,
John
^Arafura Resources Ltd, Darwin, NT (khussey @arafurare sources, com. au) Geoscience Australia, Canberra, ACT. (david. huston @ ga. gov. au), ^Exploremin Pty Ltd, Cairns, Qld (goulepll @ bigpond. com)
The Nolans Bore REE-P-U-Th deposit occurs in the southeast Reynolds Range within the Aileron Province of the Arunta Region in the Northern Territory, Australia. Country rocks include Palaeoproterozoic felsic gneisses and subordinate meta-sedimentary rocks that have undergone granulite facies metamorphism during the 16001570 Ma Chewings Orogeny, and were subsequently locally deformed during the 330-330 Ma Alice Springs Orogeny. Locahsed pegmatites are also present. The mineralisation mainly occurs as swarm of massive fluorapatite-rich veins, currendy known over about 3 x 2 kilometre area in the vicinity of Nolans Bore. This mineralisation is clearly part of a large system, the lateral and vertical extents of which are yet to be fully determined. Resource definition drilling indicates that individual veins are up to lO's of metres in width and lOO's of metres in strike length. At the time of writing, the resources were estimated to be 18.6 MT @ 3.1% REO, 14% P2O5 and 0.018% U and 0.29% Th. The mineralisation is LREE-enriched and has a distinct Ca-Sr-P-REE-U-Th-E geochemical association. The REE are hosted in fluorapatite, cheralite, monazite, allanite and minute inclusions within apatite. The fluorapatite is widespread and typically has a relatively constant whole rock REE/P across the deposit. The cheralite-rich rocks are distinctly different. Widespread but variable calcsilicate alteration hosts fluorapatite-t-allanite mineralisation. Intense kaolinite and lesser smectite alteration is also locally present. Petrological, radiogenic, stable isotope and geochronological studies undertaken to better constrain the genesis and timing of this unique deposit are reported for the first time.
ABSTRACTS alphabetically b y surname of presenting author
In situ U-Pb, O, and Hf isotope measurements of I and S-type granites from tlie Berridale and Kosciuszko Batholiths. Ryan B. Ickert', Ian S. Williams', Bruce W. Chappelf ^ Research School of Earth Sciences, The Australian National University, Canberra ACT, 0200 (Ryan.Ickert@anu.edu.au) ^ School of Earth and Environmental Sciences, University of Wollongong, Wollongong NSW, 2522 Despite decades of research there is still controversy over the nature and origin of the diverse granites in the Berridale and Kosciuszko Batholiths. This stems in large part from differing interpretations of their whole-rock and isotopic compositions. Work currently under way takes a different approach, using in situ measurements of U/Pb, and ' ' ^ W ' ^ ' m on zircon from these granites and related rocks to study the processes of magma genesis. We report new SHRIMP UPb zircon ages from the granites and show that granites previously designated as S- and kype represent discrete, not synchronous or continuous, phases of igneous activity. As a result, it is difficult to envisage their being a related compositional continuum. New, high precision SHRIMP and LAMC-ICPMS ^^^HF^^^Hf data have also been collected. Co-existing melt-precipitated zircon crystals are in isotopic disequilibrium in some cases, but this is rarely pronounced and not ubiquitous. The presence of zircon crystals precipitated from isotopically distinct melts is evidence for open system processes in the generation of some granites, or a lack of homogenisation during the partial melting of heterogeneous source rocks.
U-Pb dating of monazites from Mt. Narryer metasedimentary rocks Tsuyoshi Iizuka^ Malcolm T. McCulloctf, Tsuyoshi Komiya^ ^ Earthquake Research Institute, University of Tokyo & Research School of Earth Sciences, The Australian National University (tsuyoshi. iizuka@anu. edu. au) Research School of Earth Sciences, The Australian National University ^ Department of Earth and Planetary Sciences, Tokyo Institute of Technology Metasedimentary rocks with ca. 3.0 Ga depositional ages exposed at Mt. Narryer, Western Australia contain Hadean (>4.0 Ga) detrital zircons. Previous studies have demonstrated that detrital
zircons from the metasedimentary rocks define two distinctive age groups, an older group from 4.284.00 Ga and a younger group from 3.75-3.25 Ga. We have studied the age of monazites from the metasedimentary rocks relative to zircon \J-?b ages to constrain their provenance as well as postdepositional thermal history. About 450 monazite grains were separated from five rock samples and their U-(Th-)Pb isotopes were measured by LAICPMS. All monazite populations show a prominent peak at 2.80-2.75 Ga in the ^^^Pb/^^Pb age histograms, indicating monazite recrystallization and/or growth during the metamorphism at that time. This is consistent with hornblende K-Ar ages and zircon overgrowth UPb ages from the sequence. While the 2.80-2.75 Ga grains are dominant in the monazite populations from four rock samples, one sample yielded a significant number >3.0 Ga monazite grains (ca. 50%). The older predepositional monazite population shows a small peak at 3.6 Ga and more dominant peaks at 3.303.25 and 3.15 Ga, approximately corresponding to the minimum age of the younger zircon group. This suggests that the age variation of younger zircon group may also be due to Pb-loss from -3.75 Ga zircon during the metamorphisms at 3.30-3.25 and 3.15 Ga, rather than due to mixing of multigeneration of zircons. Interestingly, no Hadean monazites have been found here: the oldest monazites identified have a maximum age of ca. 3.6 Ga. The lack of Hadean monazite can be interpreted as indicating that the source rocks experienced a sequence of metamorphic events from ca. 3.6, or alternatively, the source rocks might be maficintermediate in composition, rather than felsic, and hence did not contain igneous monazite.
Chronology of the Early Solar System through Short-lived and Long-lived Chronometers Trevor Ireland^ and Yuri Amelin^ ^ Research School of Earth Sciences, The Australian National University, Canberra ACT 0200 (Trevor.Ireland@anu. edu. au) Constraining events to an absolute chronometric framework in the early solar system is difficult because of the short duration of high temperature processes (1-10 Ma) and the complex evolutionary history since ca. 4567 Ma. The U-Pb system offers absolute time calibration for suitable samples and gives a history of events from the nebula phase through to the planetary phase. Shortlived chronometers have also been used for developing a chronometric framework, but their utility may be compromised if the assumptions of initial radionuclide homogeneity, closed system behaviour, and constrained initial daughter-nuclide continued next page.. Australian Earth Sciences Convention 2008
143
144 ABSTRACTS aiphabeticaiiy by surname of presenting author
composition are not fulfilled. The best behaviour for both short and longlived systems is provided by differentiated meteorites. These rocks represent wide-scale melting on the parent body so that all isotopic systems are reset. Over the past several years, the consistency between isotopic systems, in particular ^^Al-^^Mg, ^^Mn-^^Cr, ^^^Hf-^^^W, and U-Pb, has been steadily improving. However, some discrepancies in the chronometric systems require resolution. Some mterestmg issues include: the initial ^^Al/^^Al of the solar system as suggested by refractory inclusions (the oldest known materials from the solar system), the potential for radial distributions of ^^Mn (and ^^Cr) in the early solar system, and whether ^^Al and ^^Fe could be significant heat sources for planetesimals.
Large Volumes of Mafic Magmatism Affecting Meso-Neoarchean Crust, Murchison Domain, Youanmi Terrane, Yilgarn Craton, Western Australia Tim Ivanic
^ Geological Survey of Western Australia, Department of Industry and Resources, 100 Plain 6004 WA Street, East Perth, (tim. ivanic @ doir. wa. gov. au) Recent mapping and SHRIMP geochronology have identified possibly four generations of Archean greenstones in the Murchison Domain. The greenstones have been intruded by voluminous syn-volcanic gabbro and subordinate granites, and then by voluminous synand post-deformational granites. New mapping, targeted geochemistry, and geochronology have provided new insights into the relationships between the gabbroic and granitic intrusive rocks, and the broadly contemporaneous volcanic rocks. This provides a new framework for crustal evolution during the Mesoarchean and Neoarchean Eras, indicating large changes in: (1) heat flux; (2) styles of mantle and crustal melting; and (3) crustal composition and structure. The mineralogy and geochemistry of mafic magmas also reveal trends of magma evolution which may link several large mafic complexes in different parts of the Murchison Province. These include: Windimurra-Narndee layered intrusions (WNLI) -20,000 km^; the Barrambie, Youanmi, Atley and Range Bore intrusions (-30,000 km^); and numerous sill complexes within greenstone belt successions (e.g. Weld Range dolerites) -2000 km\ Four discrete periods of deposition are emerging from recent geochronology. The oldest greenstones, identified by conventional and SHRIMP dating, are c. 2950 Ma in age and contain a range of rock types including BIF, and mafic and felsic volcanic rocks. A felsic volcanic and BIF suite overly this and are 2814-2799 Ma. These are Australian Earth Sciences Convention 2008
followed by 2785-2745 Ma greenstones comprising basalts, felsic volcanics and BIF-quartzite sedimentary units. A final package was deposited at 2720 Ma. At least some of the voluminous maficultramafic intrusive rocks appear to be contemporaneous with the komatiite volcanism at 2800 Ma. The layered intrusions are characterised by lobate laccolith-lopolith geometries and several pulses of magma injection, indicative of up welling asthenosphere and lithospheric stretching possibly associated with impingement of a large mantle plume associated with the 2.7 Ga global LIP event.
An Exploratory laboratory Study of the Role of Water in Seismic-Wave Attenuation
Ian Jackson\ Yoshitaka Aizawa^'^, Auke Barnhoorn 1,3 Ulrich Faul 1,4 John Fitz Gerald^ ^ Research School of Earth Sciences, Australian National University (Ian.Jackson@anu.edu.au) ^ Institute for Study of the Earth's Interior, Okayama University, Misasa, Tottori 682-0193, Japan; now at Japan Manned Space Systems Corporation, Kawaguchi, Tsuchiura, Ibaraki 300-0033, Japan ^ Now at Department of Earth Sciences, Utrecht University, 3508 TA Utrecht, The Netherlands Now at Department of Earth Sciences, Boston University, Boston, MA 02215 USA As a pilot study of the role of water in the attenuation of seismic waves in the Earth's upper mantle, we have performed a series of seismicfrequency torsional forced-oscillation experiments on a natural (Anita Bay) dunite containing accessory hydrous phases, at high temperatures to 1300°C and confining pressure (Pc = 200 MPa) within gasmedium high-pressure apparatus. Both oven-dried and pre-fired specimens wrapped in Ni/Fe foil within the (poorly) vented assembly were recovered essentially dry after 50-100 h of annealing at 1300°C followed by slow staged cooling. In contrast, it has been demonstrated that a new assembly involving a welded Pt capsule retains aqueous fluid during prolonged exposure to high temperatures - allowing the first high-temperature torsional forcedoscillation measurements under high aqueous fluid pore pressure Pf. At temperatures > 1000°C, a marked reduction in shear modulus, without concomitant increase in strain energy dissipation Q ^ is attributed to the widespread wetting of grain boundaries resulting from grain-scale hydrofracturing and the maintenance of conditions of low differential pressure P^ - P^ - Pf. Staged cooling from 1000 °C is accompanied by decreasing Pf and progressive restoration of significantly positive differential pressure resulting in a micro structural regime in which the fluid on grain boundaries is
ABSTRACTS alphabetically by surname of presenting author
increasingly restricted to arrays of pores. The more pronounced viscoelastic behaviour observed within this regime for the Pt-encapsulated specimen compared to the essentially dry specimens may reflect both water-enhanced solid-state relaxation and the direct influence of the fluid phase. The scenario of overpressurised fluids and hydrofracturing in the Pt-encapsulated dunite specimen may be relevant to the high g"' and low-velocity zones observed in subduction-zone environments.
Fluid inclusion and mineral chemical constraints on magmatic origin for metals, Cloncurry iron-oxide-Cu-Au district, NW Queensland Jacob, J. A^. Bertelli, M.\ Oliver, N. H. Baker, T.^ and Williams, P. J.^ ^ EGRU, School of Earth & Environmental Sciences, James Cook University, Townsville, Australia J aib v. aonj acob@j cu. edu.au The origin of salinity in iron-oxide Cu-Au (lOCG) deposits is debatable, either magmatichydrothermal or evaporite-derived. The volatile rich late-tectonic -1530 Ma granitoids of the Cloncurry district may have provided metals for lOCG deposits in that area, but most previous studies have focused on deposits rather than intrusions. Primary fluid inclusions from 2 magmatic suites include high salinity, multi solid varieties as well as C02-rich and H20-rich, in granites and pegmatites. This association is similar to that found in the lOCG deposits, and is verified in detail by PIXE and LA ICPMS analysis with very high Na, Ca, K, Fe, Mn, Zn, Cu and Pb. Breccia pipes emanating from the intrusions contain albitized clasts suggesting interaction with hypersaline fluids, but the fluid inclusions show only CO2- and HO-rich varieties. This suggests that the energy for brecciation was provided by large fluid pressure variations accompanying CO2 (and H2O) release from the intrusions, potentially contributing to increase in the salinity of residual salty fluids in the intrusions (and a decrease in the 5D of associated hydrous minerals). This breciation may also have been necessary to make the breccia host rocks to many of the deposits (such as Ernest Henry). Secondary inclusions of L+V+S and L+V are present in all the rocks including lOCG deposits, intmsives, breccias and barren rock formations. These fluids may or may not influence the formation of ore deposits but may have contributed to the 'basinal' fluid signal recorded by some researchers. The halogen contents of magmatic biotite and amphibole in these intusions suggests that much of the salinity was derived from the melt source regions. This challenges the theory that high salinities were derived from interaction with (meta)evaporites at the intrusion emplacement level and
supports a predominantly magmatic model for derivation of the metals in the deposits.
Facies Patterns in Carbonates of the Aptian Stage in Parnaiba Basin, Brazil and Insights From Possible Modern Analogues. Ricardo J. Jahnert^ Lindsay B. Collins ^ ^ Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth 6845, (jahnert@ terra, com. br) ^Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth 6845, (L. Collins @ curtin. edu.au) An Aptian carbonate rock sequence characterised by stromatolite and microbial facies associations is well recognized in the coastal rift type Brazilian basins and in the interior cratonic Parnaiba Basin. The Parnaiba Basin is located in the northeast part of Brazil in a 600.000 km^ area. Outcrops in the Maranhao state on the flank of the Tocantins River exhibit a facies range of a complex microbial system that characterise the Codo Formation. The correlation between the exposed rocks and data recovered from the subsurface by oil wells is consistent and an initial facies association and distribution is under construction. In outcrop eight different facies are identified, including breccias, columnar stromatolites, ranging from gently convex to paraboUc forms, microbial laminates, grainstones and siltstones and shales. Important differences are identified in the distribution and continuity of the microbial system on the Parnaiba Basin and the rift type basins microbial system formed during Gondwana breakup. While the marginal basins present a widespread and flat area exposed to marine incursion, the Parnaiba system is narrow area between the supratidal and sub tidal environment with a quickly changing facies association. This facies association will be compared with modern examples to compare rock types, facies and geomorphologic elements.
Metallogenic Endowment of Cratons, Belts and Districts: Do Bull Elephants roam in Herds? Subhash Jaireth^ David Huston^, Lynton Jaques^ ^Geoscience Australia, GPO Box 378, Canberra, ACT 2601 (Subhash.iaireth@ga.gov.au) ^Geoscience Australia, GPO Box 378, Canberra, ACT 2601 (david.huston@ga.gQv.au) ^Geoscience Australia, GPO Box 378, Canberra, ACT 2601 (lynton.j aques@ga. go v. au) continued next page.. Australian Earth Sciences Convention 2008
145
146 ABSTRACTS afphabeticaliy by surname of presenting author
The global distribution of mineral deposits in cratons, belts and districts shows that they are not equally and uniformly endowed with metal. Some cratons are highly fertile (e.g. Yilgarn Craton for Archaean greenstone gold and nickel) and there are those which are almost barren (e.g. Archaen greenstone behs in the Pilbara Craton). Within belts the distribution is equally non-uniform. For instance more than 80% of gold resources in the Yilgarn are concentrated in the Kalgoorlie Terrane of the Eastern Goldfields. At a first level the total endowment can be used to compare mineralised belts and districts. The distribution of deposit sizes in them can provide a second level constraint on their fertility, in particular the nature and intensity of metal accumulation versus metal dispersion. More enigmatic from this point of view are belts and districts in which the total metal endowment is contained in one or two giant and/or super-giant deposits, such as the Broken Hill in New South Wales, Noril'sk-Talnakh in Western Siberia, and Olympic Dam in South Australia. These major deposits represent bull elephants' in an 'elephant country'. Cumulative frequency distribution curves of metals of major mineralized cratons, belts and districts are used to compare the nature of their metal endowment. The analysis shows that the curves of 'elephant-bearing' belts and districts are remarkably different from those of 'average' belts and districts, and that regional and/or district scale geological factors could have played a significant role in controlling metal endowment. A comparison of curves for belts and districts with similar endowment can be used to assess potential for yet to be discovered deposits and to assess their relative size.
Geotourism and geoparks promote education for sustainable development. Prof Patrick James \ A/Prof lan^' Prof Jane James^ ^Clark School of Natural cfe Built Environments, University of South Australia, Australia ^Flinders University, Australia
Geological tourism is a growing global recreational and educational activity. This activity has been promoted and enhanced by an increased awareness of the need to protect and conserve our rich and varied geological heritage (geoheritage). The great range of geological and geomorphological landscapes, terrains, forms, features and processes provide a natural geodiversity which is as precious and critical as the living equivalent so keenly and passionately defended by the biodiversity lobbyists. Geological conservation (geoconservation) movements have begun to find a rightful place amongst popular, educated and scientific groups as Australian Earth Sciences Convention 2008
the awareness of the fragility of our earth's substrate and material spheres (geosphere, hydrosphere, biosphere, atmosphere) become more critical and mainstream. The key drivers for this rise in public awareness and knowledge of the importance and relevance of geological indicators, has been particularly demonstrated in Europe and China with the almost parallel development and opening of large numbers of geoparks. A consortium of more than 30 geoparks which are organised under the banner of the European Geoparks Network EGN, provided the impetus in 2002-4 for the rapid expansion of this movement, and the UNESCO supported Global Geoparks network which have constituted more than 30 geoparks in China and a few others on most continents have paved the way for the promotion of geology to much larger swathes of the global populace. The geoparks have the remit to promote and conserve geosites of special geological interest and geoheritage in general. They are also charged with promoting and enhancing geological education in all forms, sustainable development of the local park areas and a strong community linking and management of the parks. As well as raising the awareness of geology, geomorphology, hydrogeology, hydrology, palaeontology and many other facets of geoscience, the geopark agenda requires a strong underpinning of local management, consultation with a great range of stakeholders, sustainable development of communities and also environmental awareness and action. Just as geoparks provide an ideal venue for demonstrating natural geoscientific wonders, they are also key locations to educate and demonstrate the many important attributes of social, economic and particularly environmental sustainability. Material recycling, water conservation and protection, landscape stability, natural hazards, alternative energy, links with urban and regional planning are all key messages to be promulgated. Climate change, sea-level change and even tectonic change can be most readily and convincingly be demonstrated as natural geological phenomena with appropriate interpretation of the big picture geotopics of geological time, climate records and plate tectonics. Keywords - sustainability, geotourism, geoheritage, Geoparks like many other natural parks are where people recreate, study, play and work. The geoparks also allow us to widen the knowledge of the spread of geological time, the scale of catastrophic geological events such as floods and sea level changes, and the magnitude of the geological influence on our lives which can be used as a critical means to awaken public understanding of the place of geology and its fundamental role in the sustainable continuation of life on earth.
ABSTRACTS 147 alphabetically by surname of presenting author
Compiling continent wide datasets for intelligent analysis David R Jenkins\ Sim D Beams^ 1 Terra Search Pty Ltd PO Box 2016 Carlisle WA 6101 2Terra Search Pty Ltd PO Box 981 Castletown Park QLD 4812
North Hyde
The compilation of previous work by prior explorers in an area is one of the principal ways of avoiding repeating the work of others. Open File systems reporting the data collected by a company over a licence has been meticulously stored over decades. To retrieve this data geologists have moved from pouring over multitudes of reports, to compiling the data into digital formats to be manipulated and analysed to identify areas of interest as well as areas that have been effectively sterilised by previous work. Terra Search has over the last 2 decades undertaken several province, state and country wide compilations and has along the way defined some of the key techniques to ensure this data is of the optimum use to modern explorers. The power of these datasets has been enhanced as technological advances in GIS and other analytical and visualisation software have occurred. These openfile datasets should be seen as precompetitive information that is supported by the industry and government to ensure the data is as accurate and up to date as possible. These datasets result in exploration dollars being spent more efficiendy and ultimately discoveries being made more quickly or in areas which may have been overlooked.
3D Time Series Mapping of Hydrothermal Plume Behaviour Associated with Seafloor Massive Sulphides in the Eastern Manus BackArc Basin, Papua New Guinea
behaviour in back-arc basins. From 1991 to 2006, a number of distinct hydrothermal plumes were identified and mapped in the Eastern Manus basin by over 120 deployments of a conductivitytemperature-depth (CTD) transmissometer rosette, which also collected water samples for chemical analysis. The subsequent CTD, light transmission and water chemistry data from two of the major vent fields (SuSu Knolls and PACMANUS) were processed and modelled using a new 3D visualization method. In the SuSu Knolls vent field, at least four hydrothermal plumes were distinguished in the water column between approximately 900 and 1800 m depth by strong decreases in light transmission. These complex plumes displayed significant and rapid (< 1 year) temporal variations in orientation, number, intensity and areal extent. Enrichments relative to background seawater were found in Al, Cd, Cu, Fe, Mn, Mo and Zn, with low pH values typical. In the PACMANUS vent field, two temporally stable hydrothermal plumes were distinguished by relatively weak light transmission anomalies between approximately 1300 and 1900 m depth, with anomalous concentrations of Al, Ba, Cd, Cr, Co, Cu, Fe, Mn, Mo, Pb, Se and Zn relative to background seawater. These results indicate that hydrothermal plumes in back-arc basins may be complex and relatively short-lived transient systems; which has implications for the genesis and accumulation of SMS deposits.
Possible lateritic paleosol beneath the Earth's oldest (-3.4 Ga) Land Surface in the Pilbara Craton, Western Australia. Ian Johnson^ Yumiko Watanabe\ Brian Stewart^, Hiroshi Ohmoto^ ^ Penn State Astrobiology Research Center (PSARC), at the Pennsylvania State University (ijohnson@geosc.psiL edu) Dept. of Geology and Planetary Sciences, University of Pittsburgh
Shannon M. Johns^ Christopher J. Yeats^ ^ Commonwealth Scientific and Industrial Research Organisation (CSIRO), Exploration and Mining, Australian Resources Research Centre, Kensington, WA, Australia (Shannon.Johns@csiro.au) ^ Commonwealth Scientific and Industrial Research Organisation (CSIRO), Exploration and Mining, Australian Resources Research Centre, Kensington, WA, Australia (Chris. Yeats@csiro.au) Over a 15 year period, hydrothermal plumes associated with seafloor massive sulphide (SMS) formation in the Eastern Manus back-arc basin of Papua New Guinea have been characterised and mapped in 3D, providing the first study of long-term time series variations in hvdrothermal plume
We have discovered hematite (Fe203)-rich pods below the Earth's oldest (-3.4 Ga) land surface in the North Pole Dome region of the Pilbara Craton. The angular unconformity separates the felsic-tomafic submarine volcanics of the Warrawoona Group (-3.5 Ga) from the overlying Strelley Pool Formation (3.43 Ga). The Fe-pods occur in a pyrophyllite/chlorite-rich alteration zone that is 10s of meters thick and occurs over a 100,000 km^ region in the craton. Previous researchers have attributed the alteration zone to the shallow circulation of hydrothermal fluid during the eruption of the Euro Basalt (-3.35 Ga)(Van Kranendonk and Pirajno, 2004). The pods have been discovered at 7 sites spanning a - 3 0 km linear distance. The 1-6 mthick by 1-50 m-long pods occur in horizons that are continued next page... 1 Earth Sciences Convention 2008
148 ABSTRACTS alphabeticaiiy b y s u r n a m e of presenting author
up to 150 m in length and are below and parallel to the unconformity surface. The pods contain well crystalline Fe203 in concentrations between 20 to 90 wt%. We have carried out systematic mineralogical and geochemical investigations to evaluate the various possible origin(s) of the Fe-rich pods and pyrophyllite/chlorite-rich alteration zone (e.g., submarine hydrothermal mineralization, mo dern weathering, etc). The results support a strong possibility that the alteration and hematite-rich pods developed during lateritic soil formation -3.4 Ga, and were subjected to regional metamorphism -2.7 Ga. Considering the requirements for the formation of lateritic profiles, we suggest that the land surface was colonized by microbial life and the atmosphere was fully oxidized -3.4 Gyr ago.
Securing Australia's Future Wealth The Role of Precompetitive Geoscience and Geoscience Australia's Program James Johnson^ ^Geoscience Australia Australia is enjoying great prosperity from a boom in mineral commodity prices and increasing production, fuelled by demand from Asia broadly and China in particular. To date this is in no sense matched by a discovery boom. According to Access Economics, over the last 5 years Australia has lost global market share in production, and Mineral Exploration Group figures also indicate a loss of market share in exploration expenditure since 2002. This is a combination of trends that should ring alarm bells. Australia could have a dramatic increase in wealth if we are able to maintain or grow production market share, if we can meet the challenges posed. However, higher production levels will be unsustainable in the long term without significant resource replacement through discovery. Geoscience Australia has adopted an approach and undertaken a program to address the national need for resource discovery. By design it aims to provide data, information and predictive products about prospectivity, to lower risk for explorers and thereby attract more exploration investment to our shores. The current Onshore Energy Security Program employs this approach. Acquisition of seismic, radiometric, AEM and geochemical datasets is providing new knowledge about the structure and composition of the continent. Integrative interpretation of these data is producing new insights into Australia's potential for the energy commodities petroleum, uranium, thorium and geothermal systems, and for mineral commodities more broadly. This program is making a fundamental contribution to Australia's energy security and future wealth.
Australian Earth Sciences Convention 2008
The Glenburgh Terrane: a record of subduction and collision in the Paleoproterozoic Capricorn Orogen of Western Australia S.P. Johnson^ S. Sheppard\ P.B Groenewald\ S. Bodorkos^ and K. Selway^ ^Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia (simon.johnson2 @ doir. wa. gov.au) ^Onshore Energy and Minerals Division, Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia ^Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia The Gascoyne Complex is located at the western end of the Proterozoic Capricorn Orogen, a major tectonic zone that separates the Archean Yilgarn and Pilbara cratons. The oldest crust in the Gascoyne Complex is the Glenburgh Terrane, which comprises orthogneisses with protolith ages of 26602470 Ma (Halfway Gneiss), unconformably overlying post-2300 Ma psammitic and pelitic metasedimentary rocks of the Moogie Metamorphics, and a 2005-1970 Ma granitic supersuite. The terrane is only exposed in the southern part of the complex, but a recent magnetotelluric survey suggests that it forms basement to the entire Gascoyne Complex. Post-2610 Ma components of the Glenburgh Terrane have no counterparts in the Yilgarn or Pilbara cratons, which suggests that the Glenburgh Terrane evolved independently of both. Furthermore, detrital zircon populations in the Moogie Metamorphics are consistent with derivation predominantly from the underlying Halfway Gneiss, with little evidence of significant Archean cratonic input. Both units were intruded by 2005-1970 Ma granites of the Dalgaringa Supersuite, which is geochemically and isotopically similar to present-day continental-margin-arc rocks. This supersuite formed above a northwest-dipping subduction zone along the southern margin of the Glenburgh Terrane. Its subsequent collision with the Yilgarn Craton passive margin (along a suture marked by the Errabiddy Shear Zone) is termed the Glenburgh Orogeny, and was marked by medium- to high-grade metamorphism and migmatization of the Moogie Metamorphics at ca. 1950 Ma. Part of the Glenburgh Terrane was thrust beneath the Yilgarn margin, and syn-tectonic 1960-1950 Ma granites (Bertibubba Supersuite), derived from this subducted crust and the overlying Yilgarn Craton, intruded and stitched the suture. These granites represent the first element common to the Gascoyne Complex and Yilgarn Craton. Within the shear zone, metasedimentary rocks of the Camel Hills Metamorphics contain detrital zircons as young as ca. 2020 Ma, consistent with deposition in an arc-related basin immediately prior to collision.
ABSTRACTS alphabetically by surname of presenting author
Get Closer to the Truth ... with Hyperspectral Mineral Maps from Queensland Mai Jones \ Tom Cudahy^, Matilda Thomas^ Carsten Laukamp^, Rob Hewson? ^ Geological Survey of Queensland, Block A, Natural Resource Sciences, 80 Meiers Road, Indooroopilly Queensland Australia 4068. (Mal.Jones@dme.qld.gov.au ) CSIRO Exploration and Mining, Australian Resources Research Centre, PO Box 1130 Bentley, WA Australia 6151 (Thomas.Cudahy@CSIRO.au; Rob.Hewson@CSlRO.au ) Matilda Thomas, Geoscience Australia, GPO Box 378, Canberra, ACT 2601 {Matilda. Thomas@ga.gov.au) ^ Carsten Laukamp, School of Earth and Environmental Sciences, James Cook University, Townsville, Queensland Australia 4811 (Carsten.Laukamp@Jcu.edu.au) A two year program of hyperspectral mapping in Queensland is providing pre-competitive data to explorationists. Over 25 000 sq km of terrain prospective for gold and base metals was flown in 2006-7. Fifteen kilometre wide swaths were collected in areas including Mount Isa in the northwest, Georgetown - Palmerville Fault in the east, and Pajingo-Wirralie in Central Queensland. A wide range of geological terrains has been covered, containing a broad range of minerals and mineralisation styles. Stage 1 of the survey focussed on Mount Isa, and 22 GIS-compatible image products were released in July 2007. Another three products were released subsequently. The results of the more extensive Stage 2 survey will be available from July 2008, and will provide a similar suite of products. For the first time, alteration styles along major structural features can be examined. In addition, contrasts between geological terrains can be investigated and alteration signatures from proven mineralised areas can be evaluated. The images that are available include several that identify minerals such as mica, chlorite, and epidote, others that show compositional variations (eg the transition from mica to phengite) and even crystal structure (eg water associated with mica). By mapping the surface mineralogy directly, the new mineral maps provide explorers with new data to review well-studied terrains, as well as nearby areas that may have previously been overlooked. The various image products are available for free download from the internet, and can be immediately incorporated into an explorer's own GIS dataset. The hyperspectral data are also compatible with hand held spectrometer measurements of outcrops and hand samples. When
the HyLogger core and chip scanning instruments become available in each State in late 2008, hyperspectral mapping will move to the dimension, by linking the surface and subsurface mineral distributions. Understanding the distribution of minerals in 3D will be a great benefit to the search for the resources of the future.
Queensland - Program Initiatives attract Exploration Investment
to
Mai Jones \ Dave Mason^, and John Tuttle^ ^ (maLjones@dme.qld.gov.au) (dave. mason @ dme. qld. gov. au) ^john. tuttle @ dme. qld. gov.au) The Queensland Government is committed to attracting increased exploration investment to the state to underpin the discovery of new mineral and energy resources. The Smart Exploration and Smart Mining-Future Prosperity funding programs are the vehicles to deliver that competitive edge in the quest to secure a greater share of national and global exploration funding. The Department of Mines and Energy is the lead agency for these programs with the Geological Survey of Queensland and Industry Development Divisions responsible for program implementation. Significant milestones have been achieved to date via the $49.08 million in funding allocated to these programs. Smart Exploration a $20 million, four year program, commenced in 2005-06 is targeting four areas across the state - Mount Isa, Bowen-Surat Basins, Drummond Basin and the Mt Rawdon Corridor. The Smart Mining - Future Prosperity program, a $29.08 million four year program, commenced in September 2006 is targeting the Charters Towers, Cooper Basin and Cape York areas of the State. $39 million of this funding is being directed towards the acquisition of a diverse range of precompetitive, strategic, geoscientific data and information including airborne magnetic and radiometric, ground gravity, airborne hyperspectral and deep crustal seismic reflection data, exploration geochemistry data, and updated geological mapping. Collaborative research projects are also being carried out to leverage further geoscientific knowledge from the acquired data. The remaining $10.08 million in funding is being directed towards providing financial assistance to the exploration industry. Significant progress has been achieved to date with the completion of airborne hyperspectral and deep crustal seismic surveys and over 60% of airborne geophysics and gravity surveys. Queensland is already seeing the benefits of this investment in data acquisition via significant growth in land area under exploration tenure and a surge in exploration expenditure.
Australian Earth Sciences Convention 2008
149
150 ABSTRACTS aiphabeticaiiy by surname of presenting author
Carbonate aeolianite systems within the Naturaiiste-Leeuwin region of southwest Western Australia: correlation with the Pleistocene-Holocene chronology of the Perth region Diane Jorgensen^ ^ Geoscience Australia, GPO Box 378, Canberra ACT 2601 (DianeJorgensen@ga.gov.au) Aeolian activity has played an important role in the Pleistocene-Holocene landscape evolution within the Perth Basin of Western Australia. However, little attention has been given to the Tamala Limestone within the Naturaiiste-Leeuwin region. For this study, three facies (aeolianite, protosol/palaeosol and littoral conglomerate) at two localities have been examined in the NaturaiisteLeeuwin region: Whitecliff at Hamelin Bay; and Shelly Beach at Bunker Bay. At Whitecliff, the aeolianite ridge was built up in rapid stages, with quiescent periods being indicated by formation of soil horizons that were generally not long in duration. The cliff exposure at Shelly Beach preserves a littoral conglomerate overlain by a palaeosol and a large, single-set of aeolianite. The well-rounded granite conglomerate was deposited in a beach environment and preserves a sea-level at least U.8m above ADSL. Similar controls upon aeolian formation in the Perth region (shelf profile, sea-level, topography and palaeoclimate) exist within the NaturaiisteLeeuwin region. Due to the distally-steepened ramp profile of the region, sea-level must be higher than 50m below present to produce and make available carbonate sediment for aeolian formation. Wholerock AAR samples from aeolianites at Whitecliff produced concordant ratios with Aminozone C from Garden Island Ridge of the Perth region. Taking into account possible affects to the AAR ratios by taxonomy, precipitation and temperature, the aeolianites at Whitecliff are correlated to dune formation during MIS5a. The AAR results from the aeolianite at Shelly Beach are slightly older than the aeolianites at Peppermint Grove and Fremantle Fort localities but not older in age to the aeolianites at Mt Eliza. By this association, the aeolian deposit at Shelly Beach was deposited during a highstand that was either MIS9 or older. The marine conglomerate is most likely emplaced during the actual highstand of MISll, where sea-level is documented (in sealevel curves) to have risen >10m RSL.
Australian Earth Sctences Convention 2008
Evaluating the geology and petroleum prospectivity of frontier exploration areas within the offshore north Perth Basin Diane Jorgensen^ and Barry Bradshaw^ ' Geoscience Australia, GPO Box 378, Canberra ACT 2601 (Diane. Jorgensen @ ga. gov. au) The Perth Basin is a north to north-northwest trending, onshore and offshore sedimentary basin extending about 1,300 km along the southwestern margin of the Australian continent. This is a large (172,300 km^), structurally complex basin that formed during the separation of Australia and Greater India in the Permian to Early Cretaceous. The Perth Basin contains commercial oil and gas fields, which are all focussed around an intra-basin high between the northern onshore and offshore basin areas. Most oil in the basin is sourced from the Upper Permian - Lower Triassic Hovea member of the Kockatea Shale. The northern offshore component of the Perth Basin is under-explored with only 32 wells drilled, most in the Permo-Triassic Abrolhos Sub-basin and adjoining Beagle Ridge. Exploration results in these offshore areas have demonstrated the presence of a working PermoTriassic petroleum system, with hydrocarbon accumulations at Cliff Head, Frankland, Dunsborough, and Perseverance, and evidence of palaeo-hydrocarbon columns in many other wells. The petroleum potential of the other components of the offshore northern Perth Basin, the Houtman and Zeewyck sub-basins, is unknown with only two wells drilled and variable seismic coverage. Geoscience Australia has begun a study of the offshore north Perth Basin's geology and petroleum prospectivity as part of the Commonwealth Government's Energy Security Program. The approach used in this study is to integrate our existing knowledge of the structure, stratigraphy and geochemistry of the Perth Basin with new geophysical and geological data to be acquired during a series of seismic, marine sampling and geopotential surveys in the Zeewyck and Houtman sub-basins. This integrated basin study will lead to an improved understanding of the geology of the offshore north Perth Basin, and identify potential exploration opportunities.
ABSTRACTS alphabetically by surname of presenting author
Status of Database.
the
Impact
Crater
Age
Does the Capricorn Orogen control seismicity in the Carnarvon Basin?
Fred Jourdan , Paul R. Renne , W. Uwe Reimold^
Myra Keep , Brian Kennett , Stefan Revets
^ Western Australian Argon isotope facility, Department of Applied Geology & JdL Center, Curtin university of Tech., GPO Box U1987, Perth, WA 6845; Australia (fjourdan@curtin.edu.au) ^ Berkeley Geochronology Center; 2455 Ridge Rd., Berkeley, CA94709, USA (prenne@bgc.org) Museum f . Natural History (Mineralogy), Humboldt-University, Invalidenstrasse 43, 10115 Berlin, Germany (Uwe.Reimold@MUSEUM.HUBerlin.de). The Earth impact crater database (http://www.unb.ca/passc/ImpactDatabase/) includes a total of 174 confirmed impact structures. Precise and accurate age constraints are crucial in (1) correlating causes and effects on the bio- and geosphere for these catastrophic processes, (2) better constraining the impactor flux through geological time and evaluation of potential impact periodicity, (3) calibrating the absolute chronostratigraphic time scale, and (4) calibrating the age of within-crater continental sedimentary deposits (e.g., for regional paleo-climatic analysis).. Of the 174 confirmed impact structures only a few have ages constrained precisely enough (mostly using radio-isotopic techniques, e.g. U/Pb and "^W^Ar), with 25 ages having a stated precision better than + 2% and 16 ages with a precision better than ± 1%. Yet, even in this very restricted subset of the database, the accuracy of some of these ages can be challenged and probably improved based on more detailed and statistically more rigorous interpretations. These ages tend to propagate into the literature without further critical evaluation and become "robust" and widely accepted ages. A quick review of the age data of the 25 shorthsted structures suggest that 11 ages seem accurate, 12 are at best ambiguous and should not be reported with any uncertainty and 2 are not well characterized at all. We report detailed examples of misleading ages and/or age uncertainties (e.g., poor stratigraphic constraints, data over-interpretations, ambiguity due to inconsistent results) and highlight the robustness of 11 well-defined ages. We also provide some suggestions based on observations and modeling, in order to obtain better ages. This brief review should be interpreted as a call for drastic qualitative and quantitative improvements of the crater age database in the near future.
^ School of Earth and Geographical Sciences, The University of Western Australia, M004, 35 Stirling Hwy, Nedlands 6009. myra.keep @ uwa. edu.au ^ Research School of Earth Sciences, Australian National University,Building 61, Mills Rd, Canberra. Brian, kennett@anu. edu. au The northwestern corner of Australia hosts considerable seismicity, including mini- and microevents, but also hosts Australia's largest recorded earthquake (Meeberrie, 1941, M7.9). In 2005 we deployed a small network of seismometers to record natural seismicity in the region, to understand the amount, magnitude, nature and distribution of these events, and to interpret these events within a tectonic and neotectonic context. Geologically the region is largely underlain by Precambrian material, ranging from Archaean craton to Proterozoic mobile belts, including various igneous/metamorphic elements (Gascoyne Complex, Glenburgh Terrane, Narryer Terrane), all of which may have responded differently to seismicity based on their rheology, thickness and deformation history. Data from our network to date was supplemented with traces from some of the instruments of the national network and proved adequate for the calculation of fault-plane solutions of some 13 mini- and micro-events in the region. Most of the recorded events occurred along or close to known faults, although field data for movement/reactivation on these faults is sparse. However, most of our calculated events occur in close proximity to mechanical boundaries between crustal elements, indicating that the mechanical response of these elements controls the location of seismicity. We present the results of our study to date, including earthquake epicentre locations, focal mechanism solutions and relationships to mechanical boundaries both at shallow- and midcrustal levels.
Timor stratigraphy deconstructed: Neogene and ongoing collision Myra Keep^ David Haig^ ^School of Earth and Geographical Sciences, The University of Western Australia, M004, 35 Stirling Hwy, Nedlands 6009. myra.keep@uwa.edu.au Young thrust deformation in East Timor involves rocks of all ages in both thick- and thinskinned contraction at various scales. Thrust stacks of mainly Triassic-Jurassic Australian-derived continued next page.. Australian Earth Sciences Convention 2008
151
152
ABSTRACTS alphabetlcaliy by surname of presenting author
carbonates with intercalated volcanics may record the early-stage collision and intercalation of an oceanic plateau that is now preserved as a chain of thrust-stack mountains across the island. The southdirected thrusts preserved in these mountains occur inboard of and coaxial to a line of oil and gas seeps that extend across the island, with the structural loading possibly controlling the locations of the seeps. Of additional interest, late, high-angle structures, some marked by tectonic breccias of mixed Asian-Australian derivation, mark the northern boundary of at least one of the thrust-stack mountains, implying strong structural control and possible late reworking and/or exhumation along these faults. Associations of these Australian-derived thrust stack mountains structurally above preserved remnants of oceanic material (MORBs and cumulates) of probable Asian derivation requires further investigation. These oceanic remnants appear to have been emplaced late in the deformation, possibly as late as the Pliocene, and have generated thick fault gauges at their basal contacts. We present results of our structural studies in East Timor, and their implications for the processes of early-stage collision in young orogenic belts.
compositions of the Jack Hills zircons hint at the existence of enriched (crustal) reservoirs by at least 4.3 Ga (Y. Amelin et al., 1998, Nature v. 399, p. 252-255; T. M. Harrison et al., 2005, Science, v. 310, p. 1947-1950). However, determination of crust formation ages is hampered by the notoriously complex age dispersions within these grains and the associated difficulty of reliably age-correcting hafnium isotope ratios at the time of zircon crystallisation. Here, we report an in situ Hf isotope study of the Jack Hills zircons in which the Pb isotope age information was measured concurrently with the Hf isotope ratios. The simple data arrays contrast markedly with the heterogeneity apparent from some earlier studies and provide clear evidence for Earth differentiation at 4.5 Ga, with the production of both continental crust-like material and a mafic crustal reservoir with higher Lu/Hf. The continued resampling of this reservoir over 1.5 Ga argues for a substantial stabilised volume of differentiated crust, and, in tandem with oxygen isotope data, supports the existence of Hadean continents.
Continental materials on Earth by 4.5 Ga from Hf-Pb isotope systematics of the Jack Hills zircons, Western Australia
Dr. Tony Kemp^
Tony Kemp\ Simon Wilde^ Hawkesworth^ and Sasha Nemchin^
The trace element signature of Earth's continental crust resembles that of modern arc lavas, but much of the continental mass apparently formed during ancient igneous pulses that may be difficult to reconcile with subduction zone magmatism. We explore the role of plate subduction in crust generation by considering the tectonic context of whole-rock Nd isotope and zircon Hf-0 isotope data from granites of the Australian Tasmanides (515-230 Ma), an accretionary orogen that evolved by alternating back-arc basin opening and closure. Crustal growth in this area is manifest by the emplacement of granitic suites with a sizeable, but latent, basaltic component (30-90%). Nd-Hf-0 isotope-time patterns reveal that juvenile input into the granites was enhanced during extensional cycles that followed crustal thickening, cementing a link between slab rollback and continental growth. Interaction between juvenile magmas and supracrustal material deposited during prior back-arc rifting masked the bulk-rock isotope evidence for crust generation, but was integral to the formation of stable felsic crust. Metasedimentary reworking peaked at the inception of slab rollback episodes with the emplacement of peraluminous 'S-type' plutons, but magmatism becoming increasingly juvenile and 'I-type' thereafter as extension and crustal thinning continued. Subduction zone retreat added large tracts of new crust to eastern Australia in <300 Ma, providing an additional perspective on the conundrum of rapid continental growth.
Chris
^ School of Earth and Environmental Sciences, James Cook University, Townsville QLD 4811 (tony, kemp @jcu. edu. au) ^ Department of Applied Geology, Curtin University of Technology, Perth WA 6845 ^ School of Earth Sciences, University of Bristol, Bristol, BS8 1 RJ, UK There is mounting radiogenic isotope evidence for wholesale differentiation of the terrestrial planets within the first few million years of accretion, as seen for example in the formation of feldspathic meteorite suites and samples from the moon and probably Mars. It thus seems difficult to escape the generation of some differentiated crust on Earth in the Hadean era, especially if early magma ocean scenarios are valid. However mere 'crumbs' of this ancient and potentially sizeable crustal reservoir survive as individual zircon crystals, most notably from the Jack Hills and Mt Narryer regions of Western Australia. These remarkable grains have yielded a treasure trove of information about conditions in the infant Earth, yet fundamental questions remain about the volume, composition and fate of the early crust and its 'depleted' mantle counterpart. The unradiogenic Hf isotope Australian Earth Sciences Convention 2008
Isotopic evidence for continental growth during accretionary orogenesis in the Tasmanides, eastern Australia
^Jamestown University
ABSTRACTS 153 alphabetically by surname of presenting author
Links between orogenic-gold and mantle degassing of ^^Ar plus methane
Lithospheric Edges and Sutures. B.L.N. Kennett
M.A. Kendrick^ J. Walshe^ M. Honda^ D. Phillips \ K. Petersen^ ^ pmd'^CRC, School of Earth Sciences, University of Melbourne (mark.kendrick@unimelb.edu.au) ^pmd'^CRC, CSIRO Mining and Exploration, ARRC, Perth, WA6151 (john.walshe@csiro.au) ^RSES, Australian National University, Canberra (masahiko. honda @ anu. edu. au) pmd'^CRC, CET, University of Western Australia (kjpeters @ cyllene. uwa. edu. au) Gold-only ore deposits have an episodic distribution through time with peaks at 2.7, 1.9 and 0.4 Ga. Gold is usually associated with CO2-H2O fluid inclusions. As a result, metamorphic fluids generated during periodic episodes of orogeny have been widely implicated in gold mineralisation. Here we show quartz from the St Ives gold camp. Western Australia, contains CH4 fluid inclusions with mande-like values of <48,000 (mantle = 40,000-50,000; Ballentine et al., 2005, Nature 433, p 33). In comparison, CO2-H2O fluid inclusions have ^^Ar/^^Ar values of <17,000 and H20-dominated fluid inclusions have "^^ArA^^Ar values of <2000. Preliminary data obtained by crushing mixed fluid inclusion assemblages in sulphide minerals indicates a value of >10.5. This is higher than the atmospheric value of 9.8 and confirms the involvement of mande-derived volatiles in gold mineralisation (the crust has < 9.8). Gold has a high solubility in reduced fluids, and we believe methane could have been critical for gold transport and minerahsation: 4CH4-H4AuHS-h4S02 = 3C02+2H204-8H2S-H 4Au-hC This reaction may explain the common occurrence of C proximal to gold-only ore deposits and suggests CO2-H2O fluid inclusions could be evidence for the deposidonal mechanism rather than the transpordng medium. Our data suggest that the most likely source of CH4 and gold, in basement rocks at St Ives, is via serpentinisation of underlying ultramafic rocks during mande metasomadsm. In contrast, SO2 is inferred to have had a magmatic origin, in the crust, and was probably associated with some 'primary' CO2. A mande source of CH4 and gold is compadble with several independent lines of evidence including the periodicity of recendy recognised mande depledon events with peaks at 2.7, 1.9 and 0.4 Ga (Parman, 2007, Nature 446, p900). The proposed mande depledon events have the same dming as peaks in gold mineralisadon.
Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia (Brian.Kennett@anu.edu.au) Various styles of seismic imaging provide evidence for variability within major lithospheric blocks such as the cratons of Australia. The cmstal components show clear differentiation that appears to link to the properties of the mantle lithosphere. Although some cratonic sutures have a clear impact on structure in the uppermost mantle, surface wave tomography does not provide support for the concept of near verdcal link zones penetrating the full lithosphere. The transidon from a craton to a Phanerozoic belt may not have a simple configuration in depth. In eastern Australia there is evidence for a set of steps in lithospheric thickness whose configuration differs markedly from the surface "Tasman Line" marking the easternmost extent of Precambrian outcrop. The substructure of the lithosphere provides much information on the evolution of the present assemblage. The subtle features appear most clearly when informadon from multiple styles of seismic probes can be combined, so that both large and small spadal scales can be resolved.
Fracture network evaluation of Samana Anticline: Implication for assessing secondary fracture porosity of the proven reservoirs in the adjacent foreland basin, NW Pakistan M. Man Khan^ Athar Ali\ Sajjad Ahmad^ Csiki Izabella^ ^MOL Pakistan Oil & Gas, Islamabad, (irfan. khan @ molpakistan. com, athar. ali @ molpakistan. com) ^Department of Geology, University of Peshawar (yahya_sajjad@yahoo.com) ^MOL Pic Hungarian Oil & Gas Co. B.V. Budapest, Hungary, (icsiki@mol.hu) Samana Andcline is a well developed faultrelated fold exposed along the front of Tirah ranges with its southern limb thrust over the PaleoceneEocene rocks of the Kohat Foreland Basin. It is cored by carbonate and sandstone rock assemblage of Jurassic to Paleocene age that is proven reservoirs in the adjacent foreland basin. These rocks have well developed fracture network including three basic forms that are extension, shear and pressure soludon seams of meso-macroscopic scale. Extension fractures, predominantly oriented at high angle to the bedding surfaces can be disdnguished into two orthogonal sets that are parallel and transverse to the fold axis. The shear fractures observed along the Samana Andcline define a conjugate set trending continued next page... Austraiian Earth Sciences Convention 2008
154 ABSTRACTS alphabetically by surname of presenting author
northeast and northwest. Almost all the bedding surfaces within Jurassic-Paleocene rocks are characterized by well developed stylolites. Fractures density calculations reveal that it is greatest at fold culmination followed by forelimb and back limb which implies that fracture porosity and connectivity is greatest at the hinge area of Samana Anticline. The entire fracture network bears close spatial coordination with Samana Anticline suggesting that their genesis is synfolding and the Samana Anticline has itself evolved as a flexural slip fold. The Samana Anticline can serve as a case example for the type of fracture system that should have been developed in similar sub crop reservoirs underneath Kohat Foreland Basin.
Elastic Thickness of Cratons - A Global Study
Precambrian
Dr Jon KirbV. Dr Chris Swain^ ^Curtin University of Technology Elastic thickness (Te), or alternatively, flexural rigidity, is a measure of the resistance of the lithosphere to flexure under applied vertical loads. Its estimation has recently been subject to some controversy, but extensive testing on synthetic models has demonstrated the robustness of a new wavelet-based technique to image horizontal variations in Te. Here we present Te maps for all the Earth's major continents, and show that there exists a high degree of correlation between regions of very high Te and known Precambrian cratons. We support our results with seismic and thermal data where available.
3.2 Ga Island Arc Oceanic Sedimentary Sequence: Preliminary Result of the Dixon Island-Cleaverville Drilling (DXCL-Dri) Project. Shoichi Kiyokawa^ ^Kyushu University
The 3.2 Ga Cleaverville Group is formed cyclic volcano-sedimentary sequences (Kiyokawa and Taira, 1998). It contains thick basaltic pillow basalt, black shale-chert and vari-colored iron rich chert rocks, which are repeated three times. Especially, the Dixon Island Formation contains hydrothermal volcanic sedimentary sequence which contains some of the microbial evidence from the black chert sequence (Kiyokawa et al., 2006). We focus to drilling the twe black chert-shale sequences in the Snapper Beach and Dixon Island formations in the Cleaverville Group. Three holes were drilled along the Cleaverville Beach which contains middle part of Snapper Beach Formations (site CLl), lower pert of Snapper Beach Formation (site CL2) and Australian Earth Sciences Convention 2008
upper Dixon Island Formation (site DX). Each Core angle is 51 degree. As a result, total 200 m long cores we drillied. First 40 m longs were highly weathered in each layer. Sites We took following core length from 40 m below surface; CLl, CL2 are 50m long and DX is 100m long, the Snapper Beach Formation contains mainly bedded black chert with few cross-laminated fine sandstones. The Upper part of the Dixon Island Formation is formed very fine laminated sequence; such as black organic chert, white chert and pyrite layers. Preliminary result of the organic matter is that total Organic content is up to 0.1-4.5% and delta 13C 32-28 per mil. Some portions are high organic contents than previous land samples. It might be caused by weathering and surface silisification. The well laminated bed and high content organic mater suggest that organic activity is very high in this time and some kind of steady cycles sedimentation might be preserved in this sequence (eg. varve).
Tectonic extrusion of the Thomson Orogen: Australia-Asia equivalent of India-Asia deformation. Chris Klootwiik^ ^ RSES/DEMSANU
(chrisk@ems.anu.edu.au)
Paleomagnetic results from the ignimbriterich Carboniferous succession of the Tamworth Belt, Southern New England Orogen (SNEO), show a northward excursion over more than 30° of latitude with an apex in middle-late Visean. The excursion is identifiable also in limited paleomagnetic data from the Australian craton and the Tasman Orogenic System (TOS) and may have started in the Early Devonian. By middle-late Visean the promontory of the Australian craton in New Guinea reached 30''40°N, well within the latitudinal range of the Central Asian Orogenic Belt (CAOB). DevonianCarboniferous convergence/collision of northeastern Gondwana (Australia) and southern Laurasia (CAOB) is thought the cause of contemporaneous, Variscan, tectonism in the CAOB and in Australia (Alice Springs Orogeny [ASO], Quilpie and Kanimblan Orogenies). Compressional deformation in Australia was largely confined behind the New Guinean promontory, between the Lasseter Shear Zone and the Bowen-Gunnedah-Sydney Fault Zone. Convergence-driven N-S compression, hot crust in the Larapintine Graben and a free oceanic boundary, constituted Variscan Australia-Asia conditions that were comparable to the Cenozoic India-Asia indentation/ extrusion. Tectonic extrusion of ductile lower crust (and melt?) from the central Larapintine Graben caused eastward displacement of the Thomson Orogen and the Northern New England Orogen (NNEO) along the Diamantina River Lineament-Clarke River FZ in the north and along the Darling River/Cobar-Inglewood Lineaments and Cato Fracture Zone in the south. The buttress of the NNEO caused telescoping of an unpinned SNEO during Stephanian reversal of Gondwana's rotation.
ABSTRACTS alphabetically by surname of presenting author
Different tectonic grains (ASO, Quilpie, Kanimblan, kinkbanding) represent the integrated effects from the convergence/coUision on the brittle upper crust (direct N-S compression) and on the ductile, partially molten?, lower crust (hydraulic transmission, fanning out from N-S compression toward alignment with E-W pressure gradient). Seismic tomography shows continental-like velocities in the lower crust/upper mantle of the TOS and E-W fanning of SV azimuthal anisotropy in support of the extrusion model. Low (negative) magnetic anomalies in the Larapintine Graben and the TOS may represent hematite-residing Kiaman reverse remanence in the lower and upper crust and may outline lower cmstal flow throughout the TOS.
The Role of Land Use Geoscience in Urban Planning and Development in the Goldfields of Western Australia C. J. Kojan^ ^ Geological Survey of WA, Department of Industry and Resources, 100 Plain Street, East Perth, W. A. 6004 (chris. kojan @ doir. wa.gov. au) Land use in the Goldfields of Western Australia is guided by the State Planning Framework and associated policies, and specifically by the Goldfields Esperance Regional Planning Strategy (Western Australian Planning Commission, 2000) and town planning schemes for individual towns. Goldfields towns such as Kalgoorlie, Coolgardie and Ravensthorpe are experiencing strong growth and development as mining companies expand existing operations or commence new projects in the region. There is a growing demand for industrial land for service industries and housing for industry and government employees. The land use geoscientist's main objective is to ensure that the community has the opportunity to realise the full economic potential of the available land. This requires helping to ensure that adequate amounts of land are available for urban development but also ensuring that the mining industry retains access to prospective undeveloped land. The land use geoscientist initially contributes to the planning process in the Goldfields by providing geoscientific input to regional planning strategies and town planning schemes. Section 16 (3) of the Mining Act 1978 requires that a change of tenure from Crown land to private cannot occur without the approval of the Minister for Resources. The geoscientist can therefore ensure that sites proposed for development in prospective areas are adequately tested for mineralization before development is approved. Examples from Kalgoorlie, Coolgardie, and Ravensthorpe show that the provision of geoscientific advice at the planning stage has prevented the zoning and development of areas of known resources and very high resource potential, in
or adjacent to these towns. Conversely, some areas with moderate to high resource potential, in and around Kalgoorlie and Wiluna, have been rezoned for industrial or residential development. These areas are underexplored with no history of mining. Strategic sterilization drilling has been undertaken in several of these areas to enable their release for development.
Crustal architecture of Central Victoria: results from the 2006 deep crustal reflection seismic survey R J . Korsch\ D.H. Moore^ R.A. Cayley^ R.D. Costelloe^ A. Nakamura^ C.E. Willman^ T J . Rawling^ V J . Morand^ P J . O'Shea^
^ prnd'^CRC, Geoscience Australia, GPO Box 378, Canberra ACT2601 (RussellKorsch@ga.gov.au) ^ GeoScience Victoria, Department of Primary Industries, GPO Box 4440, Melbourne VIC 3001 ^ pmd'^CRC, GeoScience Victoria, Department of Primary Industries, GPO Box 4440, Melbourne VIC 3001 The -400 km long Central Victorian deep cmstal reflection seismic survey was carried out in 2006 as a collaborative project between the pmd*CRC, Geoscience Australia, the Victorian Government, Ballarat Goldfields NL, Gold Fields Australasia Pty Ltd and Perseverance Corporation Ltd, using the facilities of ANSIR. The aim was to cross several basement zones and provide information on the crustal architecture, particularly across the highly prospective Palaeozoic rocks occurring along strike to the north of the major Victorian goldfields. The Moyston Fault is a major east-dipping planar fault near the eastern edge of the Delamerian Orogen. It cuts through the entire crust to the Moho. The boundary between the Stawell Zone and the Bendigo Zone farther to the east is the Avoca Fault, which appears to be a west-dipping listric fault that links to the Moyston Fault at a depth of about 22 km, forming a Y-shaped geometry. Internal faults in the Stawell and Bendigo zones are almost entirely west-dipping listric faults, that cut the highly reflective lower crust of these zones. The boundary between the Bendigo and Melbourne zones, the Heathcote Fault Zone, forms a zone of strong westdipping reflections about three kilometres wide to a depth of at least 20 km, and possibly to the Moho. The Governor Fault, separating the Melbourne Zone from the Tabberabbera Zone, dips to the north at about 10° where the survey crosses it. The seismic character of the lower crust below the Melbourne Zone (the "Selwyn Block") is significantly different to that observed below the Bendigo and Stawell zones, and consists of several very strong subhorizontal reflections about 5-6 km thick starting at about 18 km depth, with a less reflective zone below it. Australian Earth Sciences Convention 2008
155
156 ABSTRACTS alphabetically by surname of presenting author
Geological structure of the Kumbruf volcanic arc (Bismarck Range, PNG Highlands)
Mineralogy of Mesoproterozoic high heat producing granite and mafic dyke from Mount Painter Province
Peter Kovac ^ & Isabella Abiari_^
Kromkhun^ Kamonporn and Foden^ John,
^Sancova 39, Bratislava, Slovakia (geolpeto @ gmail. com) ^Mineral Resource Authority, Papua New Guinea (iabiari @ mra. gov.pg)
Geology and Geophysics, School of Earth Sciences, University of Adelaide ^ (Kamonporn.kromkhun @adelaide. edu.au) ^ (john.foden@adelaide.edu.au)
The Kumbruf volcanic arc system along the northern margin of the Bismarck Range (PNG Highlands) consists of the Cretaceous to Eocene volcanics, volcano-sedimentary and sedimentary sequences. Kumbruf volcanics are represented by calc-alkaline lavas, basalt - andesite flow breccias, pyroclastic flows and tuffs. Eruptions were (at least partially) sub-aqueous, as indicated presence of pillow lavas and pillow breccias. Around volcanic islands barrier reefs developed, now preserved as a metamorphosed, organodetritic limestone. The marginal basin, between the continental margin and continental margin island arc was formed as a result of mantle flow driven flexure and subsidence caused by the sinking of the subducting Pacific Plate beneath the over riding Australian Plate. The sedimentary fill of this basin consists of deep-marine sequence, which gradually shallows upward and laterally towards to the volcanic arc. At the margin of the basin, periodic influxes of pyroclastic and epiclastic debris and lavas from nearby calc-alkaline volcanoes occurred, and sequence of alternating sediment-dominated and pyroclastic flow-dominated successions prevailed. On the ocean side of the volcanic arc the fore-arc basin was formed. Its sedimentary fill interfingers with the volcanic rocks. The sedimentary fill is represented mostly by lowgrade metasediments. Black thin bedded sandstone, siltstone and shale upwards gradually give way to feldspathic maroon sandstone and siltstone, intercalated by pyroclastic flows. During the Oligocene, fragments of the oceanic crust (Marum ophiolites), were thrusted over island arc and continental margin. In Early Miocene, the oblique subduction beneath the Kumbruf volcanic arc caused the partition of strain into an orthogonal component resulting in thrust faulting and right-lateral strike component expressed by NW-SE oriented faults. Mid-Miocene intrusive bodies postdate accretion of the Kumbruf volcanic arc to Australian continental platform. Back-arc basin fill hosts syngenetic sulphide mineralization; hydrothermal Cu-Mo mineralisation is connected to Mid-Miocene intrusive bodies and Marum ophiolites host Ni-Co lateritic deposits. Primary source of alluvial gold is suggested to be related to volcanic rocks.
Enriched uranium and thorium contents in the Mesoproterozoic Yerila Granite (YG), and composite dykes from the Mount Painter Province produce high heat production values. They are mainly contained within accessory minerals including allanite, zircon, apatite and sphene. Electron microprobe and LA-ICPMS analysis of major and accessory minerals is used for petrogenesis modelling. Major minerals such as biotite, amphibole and feldspar indirectly control concentrations of U and Th. They contain accessory mineral inclusions that have high U and Th concentrations. Geothermobarometry from amphibole and biotite suggests that both the YG and mafic dykes crystallised at high temperature. However, magnesio-hornblende, ferro-tschermakite and actinolite in mafic dykes formed at higher temperatures than potassium hastingsite in the YG enclave. Chemical composition of zircon, Ceallanite, Y-rich adzhikite, uraninite, coffinite, xenotime, frankdicksonite, Y-rich fluroapatite, Thrich synchysite display compositional variations which are related to saturation in the bulk magma and high fractionation. REE patterns of zircon, allanite and apatite exhibit negative Eu values caused by plagioclase fractionation. Apatite is more abundant in the mafic unit, crystallizing early in the magma cooling process. REE patterns in latecrystallised zircon exhibit both negative and positive Ce anomalies that could be the result of cocrystallization between zircon and allanite in the felsic zone of hot and dry fluorine-rich magma. Original magmatic minerals such as allanite, zircon, fluorite, sphene, apatite, amphibole, biotite and feldspar have been altered by a later hydrothermal event.
Australian Earth Sciences Convention 2008
ABSTRACTS alphabeticafly by surname of presenting author
An integrated sedimentological, geochemical and geochronological analysis of Georgetown: Constraints on basin development and paleo reconstructions. Alexis Lambeck\ George Gibson^ Narelle Neumann^ David Huston^ Ian Withnall^ ^ Geoscience Australia, GPO Box 378, Canberra, ACT260L (A lexis.Lambeck@ga.gov. au, George. Gibson@ga.gov. au Narelle.Neumann@ga.gov. au David. Huston@ga. gov. au) ^ Geological Survey of Queensland, Department of Mines & Energy, Block A, 80 Meiers Rd, Indooroopilly, QLD 4068. (Ian. Withnall@dme.qld.gov.au) Facies analysis of the Proterozoic rocks of the Georgetown inlier suggest the black shales of the Etheridge Group were formed from distal toes of deep water debris flows, below storm wave base. These results combined with whole-rock, trace elements, and Nd Sm isotope analyses, and with detrital SHRIMP U-Pb studies constrain the depositional setting and provenance of both the Robertson River Subgroup and overlying Langlovale Group. The inferred deep water setting for the Robertson River Group Subgroup contrasts with previous interpretations. The Etheridge Group is intruded by 16701690 Ma magmatic rocks providing a minimum age for sedimentation. These results suggest that the Etheridge Group may be time equivalent to the Calvert and lowermost Isa Superbasin. This study places constraints on paleo reconstruction models between Georgetown and the deep water debris flows in the Eastern succession, the Solders Cap Group. Understanding these tectonic relationships is critical to understanding the prospectivity of U and Cu within the Georgetown inlier.
Government's Energy Initiative in August 2006, a new geothermal project has been started at Geoscience Australia. This paper outlines the development, implementation and progress to date of the Geothermal Energy Project. Extensive consultation with State and Territory geological surveys and geothermal companies identified a list of key impediments faced by geothermal companies exploring in Australia. The Geothermal Energy Project aims to address those impediments that may be mitigated through geoscience input. The greatest identified geological need is an improved understanding of the distribution of temperature in the upper crust of Australia. The two existing datasets that map temperature and heat distribution - the Austherm05 map of temperature at 5 km depth, and a database of heat flow measurements - both suffer from insufficient data points compounded by poor data distribution. Predictions of heat distribution can also be made based on geological models, such as the location of high-heat-producing granites and overlying lowthermal-conductivity sediments. Geoscience Australia aims to compile further information for all of these datasets, and acquire new data where possible. Other geoscience inputs that will help improve discovery rates and/or reduce risk to explorers and investors include a comprehensive and accessible geothermal geoscience information system, a better understanding of the stress state of the Australian crust, better access to seismic monitors during reservoir stimulation, and a Reserve 6 Resource definition scheme. Increasing the awareness of Australia's geothermal potential will also assist the development of industry. The Geothermal Project has an involvement in all of these activities.
The International Geological Congress - AUSTRALIA 2012 Progress and Prospects
Geoscience Australia's Onshore Energy Security Program - the Geothermal Energy Project.
Ian Lambert \ Neil Williams \ Trevor Powell-
Ian Lambert^ Anthony R. Budd\ Fiona L. Holgate\ Edward Gerner^ Bridget F. Ayling^
^ Geoscience Australia (Ian.Lambert@ ga.gov.au, Neil. Williams @ ga. gov. au) t.powell @actewagl. net. au
^Geoscience Australia. GPO Box 378, Canberra, ACT, 2601. (Anthony.Budd@ga.gov.au, Fiona.Holgate@ ga.gov.au, Ed.Gerner@ga.gov.ay, Bridget.Ayling@ga.gov.au)
The IGC is to be held from - 10^' August 2012, in the Brisbane Exhibition and Convention Centre. This presentation will outline the opportunities that the IGC brings for the region, the status of preparations for AUSTRALIA 2012, and some attendant international geopolitics. The IGC is likely to attract at least 4000 delegates from over 100 countries. It will open up new opportunities for international research
Work conducted at the Bureau of Mineral Resources (now Geoscience Australia) in the early 1990s was instrumental in bringing hot rocks geothermal research and development to Australia. Following the announcement of the Federal
continued next page..
157
158 ABSTRACTS aiphabeticaify by surname of presenting author
alliances, encourage the careers of young geoscientists and present important opportunities for business and industry-based investment. Through an agreement with the Australian Academy of Science, the Austrahan Geoscience Council (AGC) is the legal entity responsible for the financial and legal aspects of the Congress. AGC member societies are investing financially in the IGC. Most positions on the Preparatory Committee have been confirmed; Neil Williams is the President, Ian Lambert is the Secretary General and Trevor Powell is the AGC representative. An agreement has been completed with Queensland Events, which secures financial support from the Queensland government. The theme of the Congress will be Unearthing our Present and Future; which is broadly aligned with Australia's National Strategy for the Geosciences and the UN Year of Planet Earth. The wide-ranging scientific program will include strong components on mineral and energy resources and innovative applications of geosciences in support of societal needs Over 30 field trips are planned, covering every state and territory, and selected parts of the region. A major promotion will be staged at the 33'^ IGC in Oslo, in August 2008, where feedback will be sought on our plans for the field trips and scientific program. Our role in hosting the 34^^ IGC has already presented opportunities for us to influence arrangements in relation to the International Union of Geological Sciences and the international IGC Committee.
Australia's Uranium Deposits, Resources and Production in a Global Context Ian Lambert\ Aden.McKay\ Leesa Carson-
^ Geoscience Australia, (Ian.Lambert@ ga.gov,au, Aden.McKay @ga.gov.au, Leesa. Carson @ga.gov.au) There are almost 90 significant uranium deposits across Australia, including those that have been mined. Following the announcement of major additional resources at Olympic Dam in September 2007, Austraha has approximately 33% of the world's total Reasonably Assured Resources (RAR) of uranium recoverable at <US$80/kg U. In order of decreasing importance the known resources occur in hematite breccia complex (or iron oxide copper-gold-uranium), unconformity, sandstone and calcrete deposits. Olympic Dam is the largest known uranium deposit, containing approximately 25% of global RAR (and over 22% of global Inferred Resources) recoverable at <US$80/kg U. Most of Australia's other identified resources are within Ranger, Jabiluka, Koongarra, Kintyre and Yeelirrie, the last four of which require a change in State government policy or approval from traditional owners before they can be mined. Australian Earth Sciences Convention 2008
Australia's world-leading uranium endowment appears to result from the emplacement of uranium enriched felsic igneous rocks. Some uranium deposits appear to have formed during these widespread igneous-thermal events, including Olympic Dam, but most formed subsequendy where oxidising fluids dissolved uranium which precipitated under reducing conditions. Australia accounted for some 19% of global uranium production in 2006. Canada was the only country to produce more uranium (25%) and Kazakhstan (13%) ranked third. Considerably increased uranium production has been foreshadowed from Australia (Olympic Dam expansion), Canada (opening of the Cigar Lake mine), and Kazakhstan (developing several new in situ leach mines). If all of these increases proceed as planned, uranium supply is set to exceed demand in the short to mid-term. However, significant new discoveries will be required by 2020, by which time it is forecast that the availability of secondary supplies will have decreased significantly.
Discovery of Paleodictyon in Brackish Water Environment From the Permian Of The Carnarvon Basin, Western Australia. Zhongw^u Lan\ Z.Q. Chen^
School of Earth & Geographical Sciences, The University of Western Australia, WA 6009, Australia (lanzOl @student. uwa. edu. au) Paleodictyon is one of the most distinct inchnogenera preserved on sediment surfaces. It is morphologically characterized by the pentagon- or hexagon-shaped nets. They develop as cast on top of the sandstones and outlines of the periphery are somewhat obscured. Apart from the pronounced shapes, Paleodictyon, typical of the Nerites ichnofacies of Selacher's (1967), has long been regarded as indicator of deep-water turbidite facies restricted to the bathyal and abyssal environments. However, there is increasing evidence showing that Paleodictyon is not confined to the deep-water habitat. This distinct ichnogenus is also present in shallow marine settings (e.g. Fiirsich et al., 2007), even in non-marine environments (Pickerill, 1990; Hu, 1991; Wang et al., 2005). More recently, we also found relatively well-preserved trace fossils assignable to Paleodictyon from the Early Permian brackish facies sediments of the Carnarvon Basin, Western Australia. This ichnogenus is associated with several other ichnogenera typical of brackish inchofacies assemblage. The presence of Paleodictyon in the brackish facies setting of the Western Australia not only has broadened its distributions spatially and temporally, but also further extended its bathymetry range. This fact also reveals that the ichnoassemblage rather than a single inchnotaxon can be reliable palaeoenvironmental indicator. In addition, the new material also provides some insight into biological evolution and behaviour
ABSTRACTS alphabetically by surname of presenting author
ecology of trace-producers during the climate changeover from icehouse to greenhouse in the Early Permian. 1. Seilacher, A., 1967. Bathymetry of trace fossils. Marine Geology, 5, 413-428. 2. Pickerill, R.K., 1990. Nonmarine Paleodictyon from the Carboniferous Albert Formation of southern New Brunswick. Atlantic Geology, 26, 157-163. 3. Fiirsich, F.T., Taheri, J. and Wilmsen, M., 2007. New occurrences of the trace fossil Paleodictyon in shallow marine environments: examples from the Traissic-Jurassic of Iran. Palaios, 22, 408-416.
Visualising Landscape Evolution with SRTM Data: Regional Landform Mapping in the Tanami
making them increasingly accessible to the exploration industry. The technique has also been applied to assist exploration in South America and Africa, and also in planning an Orangutan Sanctuary in Sumatra. Understanding landscape evolution, both within and between widely separated regions, will be significantly enhanced using GSWA's new SRTM landform images.
An Alternative Model for the Genesis of Gold-Arsenic Deposits Hosted in Black Shale and Turbidite Successions Ross R Large^ ^CODES ARC Centre of Excellence in Ore Deposits, School of Earth Sciences, University of Tasmania.
Richard L Langford^ ^ Geological Survey of Western Australia, Department of Industry and Resources, 100 Plain Street, East Perth, WA 6004, Australia (richard. langford@doir. wa. gov. au) Good landform visualisation is an essential first step in understanding landscape evolution, particularly in a continent that is so flat. Digital topographic data from the Shuttle Radar Topography Mission (SRTM), flown in 2000, covers 80% of the Earth's land surface with high quality but potentially undervalued elevation data, mostly at 3-second (~90-metre) resolution. The uniform quality of these data means that effective landform comparisons can be made not only across large regions in WA but also between different continents. However, this potential is only reached if visualisation techniques effectively discriminate different landforms at a range of scales. Multi-scale surface characterisation is a new approach to manipulating and visualising SRTM data that has revealed a complex landscape wherever it has been applied. LandSerf software (Jo Wood, 1996) uses a multi-scale quadratic parameterisation algorithm that is particularly effective at extracting complex landform patterns in areas of low relief. Applied to the Tanami region this visualisation method has uncovered a hitherto unknown or poorly understood pattern of large-scale dissected pediplains, sheetflood fans and relicts of a much older, possibly glaciated landscape. Relatively small-scale landforms, including the Wolfe Creek Meteorite Crater, are still well represented, further enhancing the use of the images in regional regolith-landform mapping. Effective visualisation of the landscape is essential for understanding geochemical and hydrologic vectors, and therefore of direct benefit in planning and implementing regional exploration programs. Images created by the new method of SRTM visualisation are now a component in some digital exploration packages produced by GSWA,
Organic-rich mudstones or shales, within thick packages of calcareous or siliciclastic turbidites, have long been recognised as important host rocks for major gold deposits (e.g. Victorian Goldfield, Carlin District, Lena Gold Province, Otago Schist belt). Many of the deposits in these districts are referred to as orogenic gold deposits, emphasising the tectonic and metamorphic processes involved in the concentration of gold (Groves et al., 2003; Goldfarb et al., 2005). The current genetic models propose that the organic-rich sedimentary host rocks are the traprock for gold precipitated during deformation-related fluid flow, with the gold being transported by deepsourced fluids of mantle or lower crustal origin, or in some cases from felsic magmas. Recent research at CODES (Wood and Large, 2007; Large et al., 2007) suggests the possibility that organic-rich black shales are potential source rocks for gold, arsenic and vanadium, and that the gold was originally trapped on seafloor organic material by chemical process during sedimentation and concentrated in arsenian pyrite during diagenesis. Later deformation leads to gold concentration in structural sites.
Detection of K-alteration in the Cloncurry District, NW Queensland, using Hyperspectral Mineral Maps C. Laukamp^ T. Cudahy^ N.H.S Oliver^ J.S. Cleverley^ ^ James Cook University, Townsville, QLD, Australia, 481 (Carsten.Laukamp@jcu.edu.au,Nick.Oliver@jcu. edu.au) ^ CSIRO Exploration and Mining, PO Box 1130 Bentley, WA Australia 6151 (Thomas. Cudahy @ CSIRO. au, James. Cleverley @ csiro. au) Potassic alteration in the Cloncurry District is spatially and genetically related to lOCG deposits in the eastern Mount Isa Inlier, NW Queensland. continued next page... Australian Earth Sciences Convention 2008
159
160 ABSTRACTS aiphabetlcaliy by surname of presenting author
Hyperspectral images, released by the collaborative Queensland NGMM project between GSQ and CSIRO, were validated as new tool for the detection of mineralisation related hydrothermal footprints. At the lOCG deposit of Ernest Henry geochemically discrete alteration shells correspond to distinct mineral distributions. Regional sodic-calcic alteration was overprinted by potassic alteration with coeval biotite- and magnetite-veining, which was in turn altered by Cu-Au mineralisation and K-feldsparalteration. The various envelopes of potassic alteration are interpreted as a general indicator for lOCGs in the Mount Isa Inlier (Mark et al., 2006, Min. Dep., V. 40, 769 - 801). A combination of specific mineral maps, derived from hyperspectral imaging in the VNIR to SWIR-range, is used to detect potassic alteration in the Cloncurry District. "MgOH composition-" and "Fe^^ associated with MgOH-maps" enable us to separate amphibolite facies metasediments from hydrothermal breccias and various mafic units in the field area, based on their distinct amphibole and chlorite chemistry. Within some of the mafic intrusives these maps exhibit a change in the chemistry of the MgOH-bearing silicates, characterised by an increase of the Mg-content from core to rim. A change of the whole-rock chemistry is also characterised by an increasing K-feldsparcontent towards the rim. Although K-feldspar can not be detected in the VNIR- to SWIR-range, weathering products of K-feldspar like muscovite and Illite are picked up by the "White mica abundance-" and "White mica composition-maps". The remotes sensing results are confirmed by PIMA analyses and will be compared with XRD-results. Our study shows that hyperspectral mineral maps successfully identify hydrothermal alteration patterns and can be used as a powerful tool for exploration of lOCGs in the Mount Isa Inlier.
Redox-controlled Supergene Gold Enrichment within the Sunrise Dam Palaeochannel Deposit, Laverton, Western Australia Louisa Lawrance^
watersaturated sedimentary regolith cover, including a multiphase Eocene to Miocene palaeodrainage system. Three gold enrichment types are identified associated with active iron and sulphur redox fronts within the regolith and demonstrate that gold enrichment is strongly redox-controlled. Approximately 450,000 ozs of gold were recovered from high-grade bonanza deposits, in excess of lOOOg/t, within quartz-rich sand, gravels and conglomerates at the base of the palaeochannel. Some of this gold was detrital, preserved in oxidised sediment, but most occurred in partially reduced sediment characterised by distinctive yellow goethitic staining and showed evidence of in situ chemical reworking, such as highly irregular morphologies with branching protrusions, that extend along microfractures and partially wrapped matrix detrital grains, and high-fineness gold margins, inclusion-rich extremities, micron-sized octahedral and hexagonal crystal growths on their surfaces. An upper, sub-horizontal gold enrichment zone at 18-25 m depth, extended laterally over a strike length of 700 m at a cut-off of 0.10 ppm Au, independent of sedimentary horizon and coincident with an upper iron redox front marked by strong yellow goethitic staining. Gold in high-grade portions, up to 20 g/t Au, was as high-fineness, finegrained crystals and dendrites indicative of a multiphase chemogenic origin. Less extensive, subtle gold anomalous zones also occurred at 2-8 m and 12-15 m depth. In addition to enrichment at the iron redox fronts, some of the supergene resource comprised low-fineness, micron-sized refractory gold grains encapsulated in alunite at grades of up to 5 g/t, within strongly reduced grey clay above a secondary sulphide zone characterised by supergene sulphides, mainly fine-grained framboidal pyrite and marcasite.
Recent advances in the application of hydrogeophysics and regolith geoscience for groundwater and salinity mapping and management Ken Lawrie
^ School of Earth and Geographical Sciences, The University of Western Australia, Crawley, WA, 6009 (llawrance @ ozemail. com. au)
Cooperative Research Centre for Landscape, Environments and Mineral Exploration (CRC LEME), c/o Geoscience Australia, GPO Box 378, ACT2601, Australia (ken.lawrie@ga.gov.au)
Sunrise Dam is a world-class gold deposit located on the margin of a playa. Lake Carey, near Laverton, in the Eastern Goldfields Province of Western Australia. Coarse-grained, high-grade primary mineralization within shear-controlled quartz-ankerite-pyrite veins and ankerite-silicasericite and pyrite alteration zones in Archaean sedimentary (BIF facies), volcaniclastic and volcanic rocks, has been exposed to weathering and buried by up to 80 m of semi-reduced and hypersaUne-
Efforts to manage Australia's water resources more sustainably are hampered by inadequate knowledge of groundwater resources. In many aquifers, estimates of total resource and sustainable yields are often limited by a lack of geospatial and temporal hydrogeological data, and gaps in our understanding of key hydrogeological processes. More specifically, there are gaps in our understanding of surface-groundwater connectivity, inter-aquifer leakage, and water quality variations
Australian Earth Sciences Convention 2008
ABSTRACTS alphabetically by surname of presenting author
within aquifers, inadequate mapping and quantification of groundwater recharge and discharge, and an inadequate understanding of the spatial distribution, internal characteristics and continuity of aquifers. Furthermore, our understanding of groundwater flow systems is largely conceptual and often limited by data availability. The knowledge gaps are particularly acute in Austraha's shallow regolith aquifers, many of which were deposited in complex fluvial depositional environments, modified by low temperature regolith-groundwater interactions. These aquifers are also those most heavily impacted by climate variability and change, and anthropogenic influences that are not well documented. This paper explores how recent advances in hydrogeophysics and regolith geoscience have been used to map and characterise regolith aquifer systems. A 4-D landscape analysis approach utihses an understanding of landscape evolution and scale and modern investigative approaches to the conceptualisation of aquifer systems. Of particular benefit are advances in geophysical data inversion techniques that permit the ready inclusion of constraints - geological and petrophysical, that help define spatial variations in the geometry, character, and water quality of aquifers, and inform on surfacegroundwater inter-connectivity and inter-aquifer relationships. Overall, a systems approach to the mapping and characterisation of groundwater systems enables groundwater resource and salinity management questions to be addressed more effectively.
Mathematical Relationships of Solar System Bodies Revealed Using the Single Body Breakup Hypothesis Indicate Radical Rethinking Required of Early Earth Models. T. Frank Lee ^ www.franklee-geologist, com Poster will show by diagrams how the result of inductive reasoning gave the following origin of our planets and satellites. A single, differentiated body orbiting the Sun shed its outer shell - Saturn - to give protoJupiter (pj), which had to break up internally to retain closed force-field equality. Its core broke into two bodies - terrestrial Ogaseous/"icy" - which in turn broke discontinuously into three strings of bodies. The strings were impulse ejected, the first being the major satellites, including Mars, and the last Earth, Venus, Mercury O Neptune, Uranus. Ejection of the last was two-stepped, first EarthOUranus then Venus/MercuryONeptune. Study of the sequence reveals many qualitative (chiefly chemical and isotopic) and quantitative (chiefly physical) relationships between bodies, e.g., radii, masses, densities, tilts (e.g.
tilturanus/tiltEarth=Ru/RE) planct rotations (e.g., rotationsatum = rotationjupjterxRpj/Rsatum), etc. and definitive methods for revealing relationships between, until now, seemingly unrelated bodies. Example: orbit distances of Jupiter satelhtes (in Rj) ^26.2X0.724" for n= 0, 2, 3, 5. Place Moon at n=4 and calculate its speed. Lay Europa, Moon, lo. Mars in line, touching. Calculate impulse pressures MV/H-R^ for each (V= orbit speeds. For Mars V about Sun minus Vpj [12.9]) and plot on verticals from their centres. Join line is straight. Bodies therefore originated at same time. Similarly for Titan. Several of the simpler relationships will appear on the poster. None of the above can be explained by the Nebula Theory. Some Geological Conclusions. No colhsion origin of Earth and Moon. No Earth expansion, as otherwise the body relationships discovered could not exist. No variation in tilt over time, minor wobble excepted, so Proterozoic glaciation not due to tilt. Models of Primordial and Archaean Earth and the origin of life based on Nebula Theory will prove false. Inner core of Earth should be displaced.
Reconciling Neotectonic and Seismic Recurrence Rates in SW Australia Mark Leonard , Dan Clark 1 Geoscience Australia, Canberra, ACT, Australia (mark. leonard@ga.gov.au, dan. dark@ga.gov.au) The Precambrian bedrock geology of the southwest of Western Australia has not been affected by significant tectonic activity since the Cretaceous and is considered to comprise stable continental region (SCR) crust. However, over the last 50 years the region generated the highest level of seismicity for any SCR worldwide. A cool dry climate that has persisted throughout the last several hundred thousand years combined with a many million year absence of major landscape modifying events such as glaciations provides an ideal environment for the preservation of evidence for large earthquakes. Over 30 new scarps thought to be related to surface rupturing earthquakes have been identified using high resolution digital elevation data, bringing the total for the area to sixty (Clark 2008). Half of these features have been subject to reconnaissance field verification and one has been trenched and the presence of Quaternary faulting confirmed (Estrada et al. 2006). The scarps have been used to generate a neotectonic earthquake catalogue using recently developed fault scaling relations (Leonard 2007). Fault length and displacement were used to estimate magnitude and in some cases infer multiple events. Key results include: 1. Under the right conditions fault scarps from >M6.5 earthquakes can be preserved for lOOka or more and scarps from >M7.3 earthquakes for perhaps >150ka. Approximately 20% of >M6.2
continued next page..
Australian Earth Sciences Convention 2008
161
162
ABSTRACTS afphabeticaily by surname of presenting author
and 1UU% >M6.5 earthquakes in SCK are expected to form scarps. 2. Maximum magnitude in SCR crust is likely to be ~M7.3. 3. The contemporary level of seismicity in SW WA is an order of magnitude higher than that needed to generate the scarps. However, the level of seismic activity required to generate the scarps is consistent with the historic earthquakes in the whole SCR of Australia. This supports the hypothesis that seismicity in SCR is episodic and migrates on time frames of 1-1 Oka.
Nano-Aragonite Associated With Organic Globules Supports a Biogenic Origin Of 2.7 Gyr Old Stomatolites. Kevin Lepot\ Karim Benzerara^, Pascal Philippot^ Gordon E. Brown^ ^ Equipe Geobiosphere Actuelle et Primitive, Institut de Physique du Globe de Paris, CNRS & Universite Denis Diderot, case 89, 4 place Jussieu, 75252 Paris, France (lepot@ipgp.jussieu.fr & ph il ippot@ipgp.jussieu.fr). ^ Institut de Mineralogie et de Physique des Milieux Condenses, 75015 Paris, France (benzerar@impmc.jussieu.fr). ^ Department of Geological & Environmental Sciences, Stanford University, Stanford, CA 943052115, USA (gordon@pangea.stanford.edu). The macroscale morphology of Archean stromatolites has been used as evidence of early microbial ecosystems. But as Archean stromatolites only rarely contain fossil microbes, their biogenicity is tacitly assumed on the basis of macroscopic morphological comparisons with modem structures. Biogenetic definitions, however, require microscopic examination of suspected stromatolites. We obtained an unique collection of pristine samples from a diamond drillhole that intersected the 2.7Ga Tumbiana Formation, Australia (Pilbara Drilling Project). We report the occurrence of micron-sized globules of organic carbon intimately associated with the host micritic carbonate. Scanning Transmission X-ray Microscopy (STXM) analysis revealed that these organic globules are composed of organic carbon with aromatic, aliphatic and carboxyl functional groups. High Resolution Transmission Electron Microscopy (HRTEM) analysis revealed that the organic material occurs in intimate association with clustered, 50-200nm rounded bodies of aragonite. These nano-aragonite aggregates show striking similarities with nanocarbonate spheroids associated with microbial cells and polymers in modem microbialites. The organic globules are moreover cell-like. They might have been preserved owing to their encapsulation in carbonates. Our results indicate that Tumbiana stromatolites were likely formed via in-situ microbial lithification. They also extend the geologic record of aragonite back more than 2,300 million years, with profound implications on the environmental conditions prevailing on Early Earth. Australian Earth Sciences Convention 2008
Education & Outreach - an outline of the efforts of the Geological Society of America. Gary B. Lewis ^ ^Education and Outreach Geological Society of America,3300 Penrose Place, Boulder, CO 80301, USA (Glewis@geosociety.org) The Geological Society of America (GSA) operates a highly successful and innovative Education and Outreach program which involves activities such as K-12 resource development and teacher training, interns in national parks and other public lands, mentor programs, an employment service center and the general public EarthCache program. The Teacher Advocate Program (TAP) aims to develop a pool of excited and enthusiastic teachers across the country who will be advocates for our science to their students and peers. This program has developed over 15 teaching resources and trains hundreds of teachers at conferences each year. The GeoCorpsTMAmerica program places geoscientists for 12 weeks positions within National Park and other public lands over summer. Last year 43 people were places in a wide range of sites across the country. The Mentor programs provide the opportunity for students to discuss career paths and options with a wide range of applied geoscientists at GSA meetings throughout the year. This provides students with ideas of options outside of academia. The Employment Service Center allows GSA members to upload their resume online for free and then companies to search for prospective employees from those resumes. Interviews are held at the annual meeting each year. The EarthCache program has volunteers developing Earth science related 'cache' sites around the world which the general public visit with the aid of their GPS. These sites aim to teach the visitors interesting facts about our planet. There are over 1750 sites already established in over 30 countries. All of these programs operate with the generous support of the GSA Foundation and other sponsors and donors.
ABSTRACTS alphabetically by surname of presenting author
How to Recognise Flat-Slab Subduction And Foundering: An Example In Orogenic, Magmatic And Basin Records Of Mesozoic South China Zheng-Xiang Li\ Xian-Hua Li^ ^ The Institute of Geoscience Research (TIGeR), Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia (z.li&,curtin.edu.au) Institute of Geology and Geophysics, Chinese Academy of Sciences, Qijiahuozi, P.O. Box 9825 Beijing 100029, China (E-mail: lixh@gig.ac.cn) Orogenic and accompanying magmatic belts are sometimes up to >1000 km wide and their abnormal width could not be explained by terrane accretions. We present here an example in Mesozoic South China where a ca. 1300 km-wide orogen is accompanied by a similar-sized magmatic province and an unusual basin history reflecting repeated kilometre-scale vertical tectonic movements. In our model (Z.X. Li and X.H. Li, Geology 35, 179-182, 2007) we use the subduction and subsequent foundering of a flat-slab to explain a puzzling chain of events: (1) the flat-subduction of an oceanic plateau, coupled with the overlying continental lithosphere, led to the migration of the orogenic front from coastal South China in Late Permian ca. 1300 km into the continental interior by the Early Jurassic; (2) downward pulling of the subducted flatslab at the rear of the migrating orogen, due to eclogite facies metamorphism, led to the formation of a shallow-marine basin at the wake of the orogen; (3) the eventual delamination and foundering of the flat-slab from its centre led to widespread anorogenic magmatism, lithospheric rebound and extension; (4) coastward retreat of a regenerated steep subduction system caused the coastward migration of the Jurassic-Cretaceous magmatic belt that has mixed extensional and arc signatures. In view of the extensive presence of oceanic plateaus and plume tracks in the present oceanic floor, and the geological record of plume activities dating as far back as Archean time, it is likely that flat-slab subduction has occurred throughout Earth history (J.B. Murphy et al.. Geology 27, 653-656, 1999). The South China example may thus serve as a classic case for the multiple effects of flat-slab subduction including migrating orogenesis and foreland flexure, syn-orogenic sagging behind the orogen, post-delamination lithospheric rebound, and the development of a Basin-and-Range style broad magmatic province.
Plate vs. Plume: Clues from Neoproterozoic Geodynamic Record Zheng-Xiang Li\ Shijie Zhong^ ^ The Institute of Geoscience Research (TIGeR), Department of Applied Geology, Curtin University of Technology, GPO Box UI987, Perth, WA 6845, Australia (z.li@curtin.edu.au) ^ Department of Physics, University of Colorado, Boulder, Colorado 80309, USA (szhong@Colorado, edu) The Neoproterozoic Era witnessed a serious of global geodynamic events that may be causally related: (1) the formation of the supercontinent Rodinia at 1000-900 Ma led to circum-Rodinia oceanic subduction; (2) simultaneous sinking of the subducted slabs to the lower mantle, plus supercontinent thermal insulation, led to the formation of a Rodinia superplume at ca. 825 Ma off the palaeoequator; (3) the superplume-related mass anomaly caused true polar wander event(s) between 800 Ma and 750 Ma and brought Rodinia and the superplume to the palaeoequator, and (4) superplume broke up Rodinia by ca. 750 Ma (Z.X. Li et a l , Precamb. Res. 160, 179-210, 2008). Parallels can be drawn with the Phanerozoic Pangaean history: both supercontinents had life spans of ca. 150 My, both had mantle superplume (superswell) developed beneath them, which eventually led to the breakup of the supercontinents. No true polar wander events occurred to Pangea because the superplume was on the palaeoequator. Four-D mobile-lid mantle convection modelling with reaUstic mantle viscosity structure, convective vigour and internal heating rate replicated the above processes and suggests that the Earth's geodynamic system could have been dominated by cyclic alternations between the degree-1 planform (with a major up welling in one hemisphere and a major down welling in the other) and the degree-2 planform (with two major antipodal upwellings and a girdle downwelling between them) (S. Zhong et al., 2007, Earth Planet. Sci. Lett. 261, 551-564). If the above observations and interpretations are correct, they imply that (1) the earth's history since at least the late Precambrian was dominated by cycles of supercontinent assembly and breakup, (2) circum-supercontinent subduction lead to the formation of mantle superplumes (and secondary plumes above the superplumes) that cause the breakup of the supercontinent, and (3) plumes and superplums can move rapidly relative to the Earth's rotation axis.
s Convention 2008
163
164
ABSTRACTS alphabeticaUy by surname of presenting author
The Geodynamic Map and Evolution History of the Supercontinent Rodinia. Z.X. \ S.V. Bogdanova^ A.S. Collins^ A. Davidson^ B. De W a e l e ^ R . E . E m s t ^ LC.W. Fitzsimons^ R.A. Fuck^ D.P. Gladkochub^ J. Jacobs^^ K.E. Karlstrom^^ S. Lu^^ L.M. Natapov^^ V. Pease^^ S.A. Pisarevsky^^'^ K. Thrane^^ V. Vemikovsky^^ ^The Institute of Geoscience Research (TIGeR), Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia (z. curtin.edu.au) ^Formerly at: Tectonics Special Research Centre, School of Earth and Geographical Sciences, The University of Western Australia, Crawley, WA 6009, Australia ^Department of Geology, Lund University, Solvegatan 12, 223 62 Lund, Sweden Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, Adelaide, SA 5005, Australia ^Geological Survey of Canada (retired), 601 Booth Street, Ottawa, Canada KIA 0E8 ^BGS International, British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, UK. ^Ernst Geosciences, 43 Margrave Ave. Ottawa, Canada KIT 3Y2 & Dept. Earth Sciences, Carleton U, Ottawa, Canada KIS 5B6 ^Universidade de Brasilia, 70910-000, Brasilia, Brazil ^Institute of the Earth's crust SB RAS, Lermontova St., 128, 664033 Irkutsk, Russia ^^Department of Earth Science, University of Bergen, Allegaten 41, N-5007 Bergen, Norway ^^Department of Earth and Planetary Sciences Northrop Hall University of New Mexico Albuquerque NM87131, U.S.A. ^^Tianjin Institute of Geology and Mineral Resources, CGS, Tianjin, 300170, China ^^GEMOC ARC Key Centre, Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW2109, Australia ^"^Department of Geology and Geochemistry, Stockholm University, 10691 Stockholm, Sweden ^^ School of Geosciences, The University of Edinburgh, Edinburgh EH9 3JW, U.K. ^^Geological Institute, University of Copenhagen, 0ster Voldgade 10, 1350 Copenhagen, Denmark ^ institute of Geology & Mineralogy of Russian Academy of Sciences, Koptyug ave., 3, Novosibirsk, 630090, Russia We present a synthesis of the evolution of the Neoproterozoic supercontinent Rodinia, and the first geodynamic map of Rodinia - a final product of IGCP440. We based our work on both palaeomagnetic constraints and on geological correlations of basement provinces, orogenic histories, sedimentary provenance, the development of continental rifts and passive margins, and the record of mantle plume events including Large Australian Earth Sciences Convention 2008
Igneous Provinces. The full paper (Z.X. Li et al., Precamb. Res. 160, 179-210, 2008), the Rodinia Map, and an animation of global palaeogeography between 1100 Ma and 530 Ma, are available online at: http://dx.d0i.0rg/l 0.1016/i .precamres.2007.04.021. Rodinia assembled through worldwide orogenic events between 1300 and 900 Ma, with most of the continental blocks known to exist at that time being part of it. In our preferred Rodinia model, the assembly process featured the accretion or collision of continental blocks around the margin of Laurentia. Like the supercontinent Pangaea, Rodinia lasted about 150 million years after complete assembly. Sinking of stagnated slabs accumulated at the mantle transition zone surrounding the supercontinent, as well as thermal insulation by the supercontinent, led to the formation of a mantle superswell (or superplume) beneath Rodinia 40-60 million years after the completion of its assembly. As a result, widespread continental rifting occurred between ca. 825 Ma and 740 Ma, with episodic plume events at ca. 825 Ma, ca. 780 Ma and ca. 750 Ma. The break-up of Rodinia also occurred diachronously. The first major break-up event occurred along the western margin of Laurentia (present coordinates), possibly as early as 750 Ma. Rifting between the Amazonia craton and the southeastern margin of Laurentia started at approximately the same time, but only led to breakup after ca. 600 Ma. By this time, the western Gondwanan continents were assembling, although the formation of Gondwanaland was not complete until ca. 530 Ma.
Acidic Groundwater in the South West Western of Western Australia: Its Distribution and Causes. Lillicrap, A M \ Gray, D J . ^ George, R J . ^ and V e r b o o m , W.H."^ ^Centre for Ecohydrology. Department of Agriculture and Food Western Australia / University of Western Australia, 444 Albany Highway Albany Western Australia 6330 Australia (alillicrap @ agric, wa. gov. au) ^ CSIRO Exploration and Mining, Private Bag 5, Wembley, Western Australia, 6913, Australia (david.gray @ csiro. au) ^ Centre for Ecohydrology. Department of Agriculture and Food Western Australia / University of Western Australia, PO Box 1231 Bunbury Western Australia 6230 Australia (richa rdg @ agric. wa. go v. au). ^ Department of Agriculture and Food Western Australia, 10 Doney Street, Narrogin, Western Australia 6312, Australia (wverboom @ agric. wa. gov. au) Over a million hectares of the south west of Western Australia are affected by rising watertables
ABSTRACTS alphabetically by surname of presenting author
and dryland salinity. Deep rooted plants, one main management tools for salinity, are not economically viable over much of the grain producing areas and modelling indicates vast areas of the landscape needs to be revegetated to have a significant impact on salinity. Therefore farmers are looking to engineering solutions such as deep open drainage to lower groundwater levels to reclaim saline land. However, groundwaters of this region are highly saline and commonly acidic, and when drained potentially pose an additional environmental risk to receiving water-bodies due increased metal solubility. With the increased use of engineering options such as drainage or groundwater pumping to manage saline watertables, we require a better understanding of the origins of acidic groundwaters and a riskmanagement approach based on spatial information on where acid groundwater occurs . Using groundwater bore data from government and research agencies, each bore was assigned a vegetation type, rock type, regolith type, soil landscape and depth class, where available, using spatial and groundwater datasets. Logistic regression statistical models were used to determine the statistical significance and relative importance of each of the variables (vegetation, geology, depth and regolith) in explaining the occurrence of acidic groundwater. Groundwater bores showed a distinct bimodal distribution in pH. The main population (2338 bores) had a median pH of 6.6 however; the other smaller population (694 bores) was distincdy acidic, with a median pH of 3.6. The groundwaters have high salinities, often above seawater with ion ratios similar to seawater. There was a regional trend in the occurrence of acidic groundwater with acidic groundwater least common in the steeper, higher rainfall areas and more common in the dryer, inland palaeodrainages. Within regions, the distribution was heterogenous. The hnear regression models showed that all the variables; vegetation, geology, depth and regolith had a relationship with acidic groundwater. The results were statistically significant (p <0.05). Vegetation was the strongest predictor of acidic groundwater occurrence (explaining about a third of the variability) followed by geology (10%). Acidic groundwater had the highest occurrence under certain Eucalyptus woodlands and shrublands. Two of the most common species associated with acidic groundwaters were salmon gum {Eucalyptus salmonophloia) and sand mallee {Eucalyptus eremophila). The percentage occurrence of acid groundwater is also strongly correlated (r^ = 71.7%) with percent of subsoil alkalinity in soil landscapes. Additionally, groundwaters in the wooded Kalgoorlie area showed an enrichment of iron and sulfate and depletion of calcium. Groundwaters in cleared area around Narembeen showed a depletion of sulfate and an enrichment of calcium. A conceptual model has been developed for
the origin of acidic groundwaters. Many Eucalyptus species alter the chemical and physical characteristics of the soils around their roots zones in order to command key resources such as nutrients. The Eucalypts associated with acidic groundwater utilise calcium from aerosol and/or wind-borne gypsum from playas to secrete calcrete around their roots, causing groundwater enrichments in iron and sulfate. Upon clearing for agriculture, the process at some locations has in effect been reversed as groundwaters have risen. Dissolved iron has oxidised, generating acid, and soil carbonate has dissolved with gypsum precipitating. This process leads to calcium enrichment of groundwaters and sulfate depletion.
Quantitative Assessment of Undiscovered Gold Endowment in Central Victoria Process and Implications V. Lisitsin^ A. 01shina\ D.H. Moore^^ C.E. Willman^ ^ GeoScience Victoria, Department of Primary Industries, GPO Box 4440, Melbourne VIC 3001 (Vladimir.Li sitsin@ dpi. vic.gov.au, Avi. Olshina @ dpi. vie. gov. au, David.Moore @ dpi. vie. gov.au, Clive. Willman@dpi. vic.gov. au) A recent quantitative resource assessment conducted by GeoScience Victoria indicated a rich undiscovered gold endowment under Cainozoic cover in central Victoria and a high probability of the occurrence of at least one undiscovered worldclass multi-million-ounce gold ore field. The study was based on the USGS 3-part form of assessment. It was restricted to a single deposit model - mesozonal orogenic gold. The assessment process consisted of the following steps: (1) compilation of a conceptual deposit model specific for the assessment terrane, (2) definition of permissive areas under cover (where undiscovered deposits may occur) consistent with the local deposit model, (3) compilation of a local grade and tonnage model which was compared to the available global model; a decision was made to base the assessment on the local model, (4) estimation of the likely number of undiscovered ore fields under cover through extrapolation of the local ore field density in the well explored part of the same geological terrane, (5) modelling of the total undiscovered gold endowment through a Monte Carlo simulation that combined both grade and tonnage distributions and the estimated numbers of undiscovered ore fields. The assessment indicated that: (1) quantitative results are dominated by properties of a limited number of the largest deposits, (2) the use continued next page.. Australian Earth Sciences Convention 2008
165
166
ABSTRACTS surname of presenting author
alphabetfcaliy by
of a stable grade and tonnage sub-model, which excludes the bottom 50%-70% of small-tonnage deposits, would not significantly affect modelling results while potentially simplifying the assessment process, (3) when the estimated number of undiscovered deposits is consistent with a grade and tonnage model, uncertainties in delineation of individual deposits in the model do not substantially affect assessment results, (4) assessment results can imply the presence of more than one giant deposit in the same terrane; an explicit decision on the validity of this assumption can dramatically affect quantitative results.
The Accretion Model for Orogenesis. Gordon Lister^ Mamie Forster^ ^ Research School of Earth Sciences, The Australian National University, Canberra 0200 Australia The evolution of many mountain belts occurs in the over-riding crust and mantle above subduction zones. In consequence therefore, orogens act as plate tectonic bumper bars, and they constantly react to changes taking place in the way the global assemblages of plates interact. This concept has far-reaching implications because torque balance must be maintained for each plate individually, but also amongst the entire assemblage defining the planet's lithosphere. This consequence of Newton's second law means that any event (such as a slab tearing, or the accretion of a continental ribbon, island arc, or oceanic plateau) has the potential to alter movements throughout the entire planetary lithosphere. The effects of any change will be reflected in changes in the magnitude of deviatoric stress intensity, and in the pattern of stress trajectories within the lithospheric plates. Some changes will be minor, and readily overlooked, or they will appear part of a smoothly varying continuum. Other changes will have global impact. The latter effects will remain enigmatic if geologists consider only the local environment in seeking an explanation for their cause. The build up of deviatoric stress as an accretion event gets under way may be gradual, but nevertheless abrupt changes can take place, and these may be out of all proportion to the perturbation that is modifying the system. A logical consequence of the notion that orogens act as plate tectonic bumper bars is that abrupt changes in the mode of deformation should take place in the orogenic lithosphere. Significandy, since pulses in the magnitude of deviatoric stress associated with any change the pattern of plate motions will transmit rapidly throughout the planetary lithosphere, the model predicts episodic rather than continuous evolution of orogens, and a global synchronization of the 'events' that can be recognised. Australian Earth Sciences Convention 2008
Earthquake Magnitude in the Context of Rupture Harvesting Efficiency in Different Geodynamic Environments Gordon Lister \ Brian Kennett^Marnie Forster^ Simon Richards^ ^ Research School of Earth Sciences, The Australian National University, Canberra 0200 Australia Earthquakes take place because elastic potential energy stored in stressed rock is abrupdy released as the result of catastrophic failure. In rock mechanics terms this takes place because a yield stress is exceeded, leading to formation of a fracture and its propagation. The fracture, however, runs only as long as elastic potential energy stored in the stressed rock mass can be harvested. Earthquake magnitude therefore is a function of the magnitude of the deviatoric stress intensity integrated over the region from which the propagating earthquake rupture is able to collect energy. Assuming newly broken faults are weak, the magnitude of a large earthquake is thus primarily determined by the ability of the propagating rupture to collect energy from a large area. Earthquakes therefore must be regarded not only as releasing stored elastic potential energy during catastrophic failure, but as harvesting stored elastic potential energy over the area traversed by the propagating rupture. The harvesting efficiency can be formulated as the contraction of two 3x3 matrices: 1) reflecting spatial distribution of stored elastic potential energy, here approximated by the locations of known hypocentres; 2) reflecting the orientation of the fault plane and of the slip line for an individual earthquake. The technique is investigated using known hypocentre concentrations, in particular those that define planes, such in intermediate depth seismic zones beneath the Japanese islands, Tonga, or Myanmar. What emerges is somewhat surprising, since planar hypocentre concentrations rarely coincides with the orientation of earthquake ruptures. The harvesting efficiency of ruptures in such geodynamic environments is therefore remarkably low. However, ruptures on giant megathrusts above gentiy dipping subduction zones offer highly efficient harvesting mechanisms. Such tectonic environments are also capable of storing planar lenses of elevated deviatoric stress over large areas. Therefore giant megathrusts often mark the locations of great earthquakes.
ABSTRACTS alphabetically by surname of presenting author
A Tectono-sedimentary Model for Intracratonic Basin Fill: Examples from the Jurassic Surat Basin, Australia and the Lower Permian Ordos Basin, China
QEMSCAN chemical imaging of textures and structures within carbonaceous chondrites and iron meteorites Chi V. Ly\ A. Biondo^ D.R. Nelson^
Keyu Liu\ Trent C. K. Liang^ and Hongtao Zhu^ ^ CSIRO Petroleum, P.O. Box 1130, Bentley, W.A. 6102, Australia. (Keyu.liu@csiro.au) ^ Geological Survey of Western Australia, 100 Plain Street, East Perth, W.A. 6004, Australia ^ Faculty of Earth Resources, China University of Geoscience, Wuhan 430074, China. Intracratonic basins are characterised by stable tectonic regimes, extremely low geomorphic gradients and enclosed depositional systems with finite accommodation. Compared with sequence stratigraphic models for classic marine sequences the characteristics of intracratonic sequences are unique in terms of tectonic setting, sediment supply, base-level variations and basin physiography. During the intracratonic basin fill, the receiving basin would be filled up gradually by sediments derived from within the craton. As the basin is being infilled, sediment supply diminished and depositional gradients lowered, more distal depositional environments can migrate towards the basin margins accordingly. Assume the volume of water in the basin remains relatively constant; sediment accumulation in the basin depocentre can increase the base-level elsewhere within the basin. The relatively low gradients (<1:1000) would facilitate a large margin-ward shift in facies with only a relatively minor rise in base-level. The overall sequence succession in such a basin is characterised by back stepping. The extremely low morphological gradients can result in a huge littoral zone around the receiving basin. Excellent reservoir deposits may be developed at the distal part of the fluvial system near the littoral zone. Two intracratonic sediment sequences from the Surat Basin, Australia and the Ordos Basin, China exemplify the characteristic stratigraphicsedimentary features of the tectono-sedimentary model proposed. The Early to Middle Jurassic Precipice Sandstone-Evergreen Formation succession in the Surat Basin is characterised by two asymmetrical upward fining (retrogradational) fluvial and fluvial-lacustrine successions including a progression from braided stream deposits at the base through to meandering stream, floodplain and overlying lacustrine deposits at the top. The Lower Permian Shanxi Formation in the Ordos Basin, China, which is a major hydrocarbon producing interval, also comprises three asymmetrical retrogradational sequences from sandy braided channel deposits to shaly swamp deposits with well developed lowstand systems tracts as the major reservoirs.
^ Research Resources, CSIRO Minerals, Bentley, WA (Chi.Ly @ csiro. au) Discipline of Applied Physics, Curtin University of Technology, Perth, WA (andreaatuni@gmail.com and d.nelson@curtin.edu.au) A new non-destructive method applying a QEMSCAN instrument fitted with four x-ray detectors for the determination of the mineralogy and for the imaging of chemically distinctive textures and structures within carbonaceous chondrites and iron meteorites has been developed and applied to investigate the genesis of CAI and chondrule inclusions that may have formed within the solar nebula and matrix minerals that may have formed within disrupted differentiated planetesimals. Preliminary results from the application of this new analytical technique at a resolution of <10 |am have been obtained from CAI's and chondrules within the Allende meteorite. Analysis of an Allende CAI a few mm in diameter has distinguished ca. 10|am-sized hibonite dust grains and metallic iron fragments embedded in one of two Ca/Al phases that are heterogeneously distributed and incompletely mixed, possibly as a result of thermal metamorphism. The low Ca/Al phase also forms a thin rim around the exterior of the CAT Detailed mineral textures and intergrowths, including textures that might have arisen as a result of quenching and impacts, have also been distinguished in a number of Allende chondrules. Radiogenic decay products of more than 12 short-hved radionuchdes have been identified within primitive meteorites, affirming that a stellar nucleosynthesis event occurred within 2 Ma of the onset of formation of our solar system and may have triggered its formation. The nature of the last stellar source that contaminated our solar system's precursor molecular cloud with freshly synthesized elements may be inferred from determination of the relative abundance of short-lived nuclides in the earliest-formed and best-preserved inclusions identified within meteorites. The newly developed QEMSCAN imaging technique will provide not only information directly regarding the evolution of differentiated planetesimals, but also facilitate identification of minerals within inclusions of interest for future isotopic analysis.
Australian Earth Sciences Convention 2008
167
168 ABSTRACTS alphabeticaily by surname of presenting author
Confirmed LL Chondritic Meteorite Within The Melt Sheet of the Giant Morokweng Impact Crater, South Africa W. D. Maier^ M.A.G. Andreoli^ I McDonald^ 1. Franchi^, R. Greenwood"^ ^ Centre for Exploration Targeting, University of Western Australia, Crawley 6009. ^South African Nuclear Energy Corporation, Pretoria 0001 South Africa, and School of Geosciences, University of the Witwatersrand, Wits 2050. South Africa. ^School of Earth, Ocean & Planetary Sciences, Cardiff University, Cardiff CFIO 3YE, UK. "^Planetary and Space Sciences Research Institute, The Open University, Milton Keynes, UK. The 145 My Morokweng impact crater is one of the largest impact structures on Earth (probably -250 km diameter), and it contains one of the thickest melt sheets (> 900m). Towards the base of the melt sheet we found a large (25-cm), unaltered, fossil meteorite. This discovery was surprising as large objects are widely beheved to be completely melted or vaporized during high-angle impact with the Earth. The large clast resembles an LL6 chondrite breccia, but contains anomalously ironrich silicates, Fe-Ni sulphides, and no troilite or metal. It has chondritic chromium isotope ratios, O isotope ratios typical of LL chondrites =3.92, 6^^0=5.00), and identical platinum-group element ratios to the bulk impact melt. These features allow the unambiguous characterization of an impactor at a large crater. The unusual composition of the meteorite could suggest that the Morokweng asteroid came from part of the LL chondrite parent body not represented by objects presently reaching the Earth.
The Kabanga Nickel Deposit, Western Tanzania. W.D. Maier\ S.-J. Barnes^ T. J. Livesey^ ^Centre for Exploration Targeting, University of Western Australia (wdmaier@cyllene.uwa.edu.au) ^Sciences de la Terre, Universite du Quebec, Chicoutimi G7H 2B1, Canada ^Barrick Gold Corporation, PO Box 212, Toronto, Ontario M5J 2S1, Canada The ca. 1.4 Ga Kabanga Ni deposit (inferred resources ca. 45 Mt @ 2.6% Ni) occurs within the Kibaran orogenic belt of western Tanzania and Burundi. The ores are hosted by a cluster of ultramafic-mafic sill-like intrusions emplaced into low- to medium-grade metamorphosed mica schists and graphitic schists which may contain abundant sedimentary sulfides. The largest deposit occurs within the relatively small Kabanga North intrusion (10s to a few 100s of metres wide). Mass balance calculations indicate large ratios of sulfides to silicates and ultramafic to mafic lithologies in the intrusions, suggesting emplacement of olivinepyroxene-sulfide crystal mushes. The parental magma to the intrusions was originally picritic (ca. 16.5% MgO, 52 % Si02,), but has been variably contaminated with the host rocks during emplacement. The sulfide- and Ni rich intrusions assimilated up to ca 20% crust, resulting in a magma with ca. 14% MgO, 54% Si02, Fo 70-90, Ni/CUsuiMes ca. 8, Pd/Ir 5-20, strongly enriched incompatible trace element contents, distinct negative Nb-Ta and Ti anomalies, heavy S isotopic signatures (S^'^S -hlO to +24), and highly Ni depleted olivines (<100-1600 ppm Ni). The key factors in Ni ore genesis are (i) Crystallization of the intrusions from relatively primitive (MgO, Cr-, and Ni-rich) mantle-derived magmas that were capable of heating the country rocks sufficiently for assimilation to occur, (ii) the presence of S-rich sedimentary country rocks that provided a source of external S, and (iii) the occurrence of relatively small and dynamic magma conduits in which magmatic sulfides could be concentrated to form economic deposits.
ABSTRACTS alphabetically by surname of presenting author
Systematic PGE Depletion in Early- to Mid-Archean Komatiites from the Pilbara and Kaapvaal Cratons WD Maier\ S-J Barnes^ RH Smithies^ ^ Centre for Exploration Targeting, University of Western Australia, Crawley 6009, (wdmaier@cyllene.uwa.edu.au) ^Sciences Appliquees, Universite du Quebec a Chicoutimi, G7H2B1, Canada ^Geological Survey of Western Australia, East Perth 6004 Early to mid Archean (3.5-3.2 Ga) komatiites from the Kaapvaal and Pilbara cratons are systematically depleted in PGE relative to late Archean (2.7 Ga) komatiites from the Yilgarn, Zimbabwe and Superior cratons. The most significant depletion applies to Pt and Pd (by a factor of ca. 50-70%), with Rh, Ru, and Ir being less depleted (10-30%). These observations could be explained in several ways: (i) Sulphide melt saturation and PGE extraction from the magma during emplacement in the crust. This model is inconsistent with the variable depletion of the individual PGE in the magma. It is also difficult to understand why the early- to mid-Archean komatiites should be more amenable to sulfide saturation during emplacement than the younger komatiites. (ii) Incomplete dissolution of mande sulfides in the komatiites during relatively low degree, high-P melting of hot Archean mantle. This model is also inconsistent with the enhanced depletion of PPGE relative to IPGE in the komatiites. (iii) Melting of a depleted, subsequently refertilized (metasomatised) mantle source. This model is most consistent with the observed PGE distribution patterns, but is difficult to reconcile with the unmetasomatised nature of Pilabara mande xenohths (Griffin & O'Reilly, 2007, in van Kranendonk M, Smithies RH, Bennett VC, Earth's Oldest Rocks, 1013-1035).
A Benchmark for Best Practice in Assessing Australia's Mineral Endowment Antony Mamuse^ ^University of Western Australia & Curtin University of Technology Quandtative mineral resource assessments provide useful information for policy decisions concerning mineral supply, land use and the environment. Superior unbiased geoscience is a must in these assessments given their impact on decisionmaking. Traditionally, these assessments have employed the United States Geological Survey's (USGS) three-part method, which consists of (1) delineadon of permissive tracts, (2) estimation of grades and tonnages of undiscovered deposits, and (3) estimation of the number of undiscovered deposits. This study aims to develop an alternative approach to assessing Australia's mineral endowment. The Eastern Goldfields Superterrane (Yilgan craton. Western Australia), a world class mineral province, will be the training and testing ground for the benchmark study which will initially focus on komatiite-hosted nickel sulphide deposits. In the USGS approach, the mineral deposit density for a particular type of mineral deposit in well explored 'control areas' is often used to estimate the number of undiscovered deposits of that type in less explored geologically similar areas. Although this approach can provide useful global estimates of the number of undiscovered deposits within the targeted less explored areas, it is not indicative of the usually more important local distribution of mineral deposits. Spatial statistics will be used to extend the concept of mineral deposit density to encompass the degree of deposit dispersion or clustering. Key neighbourhood statistics will be employed to identify and define hierarchical deposit clusters. An attempt will be made to utilise these statistics in an appropriate Poisson, binomial, fractal or other distribution model. The distribution patterns will be explained in terms of existing descriptive mineral deposit models. The new spatial mineral deposit model, coupled with deposit attributes such as tonnage and grade, will be modelled to estimate total and residual nickel sulphide endowments. Applicability of power law distributions, such as Zipf's Law, in such estimations will be tested.
Australian Earth Sciences Convention 2008
169
170
ABSTRACTS aiphafoetlcally by surname of presenting author
The Significance and Origin of the Biomarker Crocetane in Devonian Source Rocks and Crude Oils (Western Canada Sedimentary Basin and Canning Basin, WA) Ercin Maslen\ Kliti Gnce\ Brian Horsfield
Julian D. Gale\
^Department of Applied Chemistry, Curtin University of Technology, GPO Box U1987,Perth, WA,6845, Australia (E. Maslen @ exchange, curtin. edu. au, K.Grice@curtin.edu.au, J.Gale@curtin.edu.au ) ^GeoForschungsZentrum (GFZ) Potsdam Section 4.3 Telegrafenberg, D-14473 Potsdam, Germany (horsf@ gfz-potsdam. de) Two most pronounced mass extinction events of the Phanerozoic include those spanning the Permian-Triassic (P/Tr) and Frasnian-Famennian (F/F) boundaries. Biomarkers derived from green sulfur bacteria (GSB) in a petroleum drill core from Western Australia spanning the P/Tr event have been recendy reported (Grice et a l , 2005, Science, V.307, p. 706). GSB are strict anaerobes that require light and hydrogen sulfide in stratified water columns to carry out photosynthesis and are thus markers for photic-zone euxinia (PZE) in depositional environments. Crocetane, an irregular tail-to-tail C20 isoprenoid in sediments derived from gas hydrate settings and methane-rich-mud volcanic sediments, is a molecular indicator for the anaerobic oxidation of methane (e.g. Thiel et al., 1999, GCA, V. 63, p.3959). This compound has been detected in sediments comprising archaea mediating oxidation by reverse methanogenesis in co-operation with sulfate reducing bacteria (e.g. Thiel et al., 1999). Moreover, crocetane has been reported in Western Australian crude oils from the Canning Basin of Devonian age (Barber et al., 2001, Org.Geochem., v. 32, p. 943; Greenwood and Summons, 2003, Org. Geochem., v. 34, p. 1211). However, the discrete source of crocetane in Devonian samples and especially crude oils remains ambiguous. The present study comprises detailed molecular study of crocetane and PZE biomarkers in sediments of the Western Canada Sedimentary Basin (WCSB, Devonian) covering a range of thermal maturities. In addition, a series of oils generated from source rocks of the basin have been analysed for crocetane. Crocetane was found to be present throughout the WCSB and all crude oils of Devonian age globally. The biomarker crocetane was found to increase in abundance with thermal maturity. Based on structural similarities of crocetane to GSB biomarkers we propose crocetane is a diagenetic product of PZE biomarkers and thus a new marker of these speciaHsed conditions. Crocetane can still be identified in samples that have Australian Earth Sciences Convention 2008
undergone significant thermal maturity and is a molecular indicator of PZE in highly matured F/F boundary samples. Interestingly the highest abundances of PZE markers are recorded in the Larapintine petroleum system, Australia, which includes Late Devonian reef complexes. It is becoming apparent that PZE conditions were pervasive through certain periods of geological time, and were particularly associated with mass extinction events (P/Tr and F/F).
Thermochemical Controls on Subduction of Oceanic Plateaus.
the
Mason W. G.\ Moresi L^^ Betts P. G.^ ^ School of Geosciences, Monash University, Clayton, VIC, Australia (Wendy. Mason@sci. monash. edu. au; Louis. Mores i@sci. monash. edu. au; Peter.Betts@sci. monash. edu. au) ^ School of Mathematical Sciences, Monash University, Clayton, VIC, Australia Elevated regions on the ocean floor such as oceanic plateaus and aseismic ridges eventually arrive at subduction zones, where they may influence trench shape and morphology of the subducted slab. New two and three dimensional thermochemical numerical models of a convergent zone have been developed, using the finite element Geoscience research code Underworld, in which an oceanic plate embedded with a plateau subducts beneath an overriding continental or oceanic plate. Model parameters such as size, age, density and thickness of the plates and plateau were varied, to investigate how these elevated features may influence subduction zones. Model results are compared with relevant geographic locations.
Palaeozoic Granites in Central Queensland: A Transect Across the Thomson - New England Orogen Boundary; Implications of the Role of Crustal Composition for Granite Formation. Emma Mathews\ Dave Champion^ Bob Bultitude^ ^ Geoscience Australia, GPO Box, 378, Canberra, A CT 2601 (david. champion @ ga. gov. au, emma. mathews @ ga. gov. au) ^ Geological Survey of Queensland, Department of Mines and Energy, Block A, 80 Meiers Rd, Indooroopilly, QLD 4068 (robert. bultitude @ dme. qld. gov. au) The Ravenswood - Bowen region of central Queensland, straddles the boundary between the Thomson (TO) and the New England (NEO)
ABSTRACTS alphabetically by surname of presenting author
Orogens. The widespread Carboniferous to Permian granites (Kennedy Province) which occur in both orogens have been studied to determine if they can be used as indicators of tectonic and crustal differences across this boundary. The northern NEO is characterised by dominandy mafic to intermediate rocks (gabbro, mafic granodiorite), ranging in age from about 310 to 275 Ma (e.g., Allen et al., 1998). Field relationships are often complex with abundant evidence of magma mingling and mixing. The rocks are geochemically and isotopically primitive. Widespread magmatism continued until the Cretaceous (ca. 130-120 Ma). In contrast, the TO is dominated by rocks of granite to (locally) granodioritic composition. Mafic rocks such as gabbros are locally present but there is minimal evidence for interaction with the felsic rocks. The TO rocks are in general more potassic and LILErich, and more isotopically evolved, than their NEO counterparts. High heat-producing granites (with strong radiometric signatures) are common in this eastern part of the TO. Comparable rocks also occur within the NEO but where present are typically younger (Mesozoic). The boundary between the two orogens appears to correspond to the Millaroo Fault Zone, which is evident on regional magnetic and radiometric images. The change in granite character across the boundary is interpreted to reflect both differing tectonic environments and the response to the nature and age of pre-existing crust within the respective orogens, i.e., older, more evolved continental crust in the TO. The changes in magmatism also has implications for metallogeny, with the TO being more favourable for lithophile element mineralisation such as. Mo, U and intrusionrelated gold; whereas the NEO is more prospective for Cu, Cu-Au and Cu-Mo.
A regional landslide programme in Tasmania
susceptibility
Colin Mazengarb^ ' Mineral Resources Tasmania, PO Box 56, Rosny, Tasmania 7018. Debris and earth flows, rock falls and deep seated landshdes pose significant risks to communities in Tasmania. In response to this risk the Tasmanian Government, with support from Local and Federal governments, is undertaking a regional scale (1:25000) mapping programme to provide an assessment of landshde susceptibility of major urban areas. The methodology involves assembling information about the geology, geomorphology and mapped landslides. Extensive use of GIS and database technology allows storage and analysis of the spatial data and associated attributes. A fieldwork component aims to detail processes relevant to landscape evolution and measure
landslide parameters for use in modelling and validation purposes. A geomorphic approach to dating landscape features is attempted in some instances. Deterministic GIS modelling techniques are employed to produce predictive susceptibility maps. Hazard maps (sensu stricti) are currently not attempted because of insufficient knowledge of likelihood. The maps represent a major advance in the knowledge base available for stakeholders. Councils are using the information to flag the need for geotechnical assessment in susceptible areas in response to development applications. Additionally, councils are gaining confidence in insisting that geotechnical investigations are in accordance with Australian Geomechanics Society Guidelines.
Toward an Understanding of Tsunami Risk in Tasmania Colin Mazengarb^ ^ Mineral Resources Tasmania, PO Box 56, Rosny, Tasmania 7018. When emergency managers in Tasmania considered the potential effects from tsunami after the 2004 Boxing Day event, the risks to the State were virtually unknown. There had been little previous research into this hazard preventing informed planning for future events (assuming that future events were in fact possible). A research project involving several organisations was undertaken to seek the answers. The project included: identification of likely sources and their wave generating potential; deep water wave modelling; shallow water wave modelling to determine inundation; and risk modelhng. The most likely source for a tsunami is a subduction event along the Puysegur Trench, an area about which very little is known other than its geometry. While geometry can be used to constrain maximum tsunami amplitude, it is not known whether large waves have been generated in the past and, assuming they are possible, how often they are likely to occur in the future. To address this deficiency a paleotsunami investigation was undertaken on several coastal sites in the greater Hobart area. The results suggest that two large events possibly occurred in the Holocene. Further work is in progress including investigations of other sites to confirm the paleotsunami hypothesis as well as a search of historical records to identify previously overlooked events. The combined evidence of past events will allow construction of size-frequency curves and likelihood prediction. In addition the tsunamites will be back-analysed to determine the minimum wave height necessary to form the deposits and thus constrain the shallow water inundation models. A superior DEM will be acquired from a planned continued next page... I Earth Sciences Convention 2008
171
172 ABSTRACTS alphabetically by surname of presenting author
LIDAR survey to enable better modelling ot the coastal inundation zone. The final step in the science will be the risk modeUing component. The effective communication of the results to key stakeholders is a component that is gready assisted through the close interaction of the science providers and the local emergency management agency. The ongoing challenge from the perspective of a science provider perspective is ensuring that future investment in tsunami science is commensurate with the identified risks.
Investigations of the Cultana Subsuite: An Outcropping Felsic Intrusive Hosted Olympic Dam - Style Alteration System. Stacey McAvaney^ ^ Primary Industries and Resources South Australia, GPO Box 1671 Adelaide, SA. 5001 (mcavaney. stacey @ saugov. sa. gov. au) The Cultana Subsuite is a low level intrusive / sub-volcanic felsic igneous suite which is found in the Cultana Inlier, in the north-eastern Gawler Craton, South Australia. It is part of the -1590 Ma Gawler Range Volcanics and Hiltaba Suite igneous system, a co-magmatic volcanic and intrusive system which hosts the mineralisation at Olympic Dam. The Cultana Subsuite consists of a range of comagmatic felsic lithologies, including granite, micro-granite, aplite, feldspar - quartz granophyric porphyry and quartz - feldspar porphyry. The subsuite is unique in that it represents a depth interval of the GRV - Hiltaba suite system that is rarely seen in outcrop, and similar low level porphyritic and granophyric intrusives may extensively underlie the Gawler Range Volcanics. The subsuite has been effected by a number of alteration phases; sericite, tourmaline - quartz and haematite - quartz alteration. Feldspar phenocrysts and groundmass feldspar in the porphyritic and aplitic lithologies have undergone extensive sericitisation. A phase of tourmaline - quartz alteration has effected all the lithologies in the suite, in the form of tourmaline suns and tourmaline and tourmaline - quartz veining. Haematite alteration is pervasive, and haematite occurs as a common late stage or secondary mineral in all lithologies. The strongest haematite alteration is localised in the quartz - feldspar porphyry, as network haematite and haematite - quartz veining and jig-saw - style haematite brecciation. Tourmaline and haematite vein orientation is largely controlled by a prominent steeply dipping fracture system with a principle set striking NNE to ENE and a minor set striking SE, which shows evidence of extensional and hybrid movement. The Cultana Suite has potential for lOCG - U mineralisation, but is under-explored due to land
Australian Earth Sciences Convention 2008
access restrictions. Geochemical sampling has revealed significantiy elevated REE across the suite, and localised anomalies in Au, Cu, andCo in haematite - altered lithologies.
William Blandowski's 1850s Explorations of the Geology and Landscape of Southeastern Australia Doug McCann^ ^School of Life & Environmental Sciences, Deakin University, Melbourne Campus, 221 Burwood Highway, Burwood VIC 3125. William Blandowski was an influential member of the scientific community in Victoria in the early 1850s and a founding member of the Philosophical Society of Victoria (PSV), a precursor organisation to the Royal Society of Victoria. Blandowski was one of a number of Germanspeaking immigrants who made significant contributions to the exploration, collection and documentation of the natural history of the fledgling colony. He was appointed Government Zoologist on March 1854 and was a knowledgeable all-round naturalist. He had received a geological education during his training as a mining engineer in Silesia, and in 1851 he is reported to have had some success as a gold miner at Forest Creek (Castiemaine). He was co-founder of a short-lived Geological Society in 1852, and in 1854 set up a new Museum of Natural History (now the Melbourne Museum). In 1854 and into 1855 he undertook several excursions to coastal areas of the Mornington Peninsula and Western Port, and inland to Central Victoria. In December 1856 he led an expedition to the junction of the Murray and Darling Rivers collecting numerous specimens. The results were published in seven papers in the Transactions of the Philosophical Society. Blandowski left Victoria for Silesia in March 1859 where he became a successful photographer. He died 18'^ December 1878.
Timor stratigraphy reconstructed: Permian to Middle Jurassic E. McCartain^ ^School of Earth and Geographical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia (mccareOl @ student.uwa.edu.au) One of the problematic aspects of Timor geology has been the juxtaposition of Permian to Middle Jurassic strata of similar age but contrasting facies. Earlier workers reconciled this juxtaposition by interpreting two different palaeogeographic origins for the strata. Some units were placed in what is today known as the Banda Terrane
ABSTRACTS alphabetically by surname of presenting author
indicating Asiatic origins whereas other units were placed in what is now known as the Gondwana Megasequence. Based on recent field work we interpret all the Permian to Middle Jurassic strata in East Timor as the Gondwana Megasequence. The contrasting strata of similar ages are interpreted to reflect the heterogeneity of depositional environments present on the northeastern Gondwana margin during many intervals of the Permian to Middle Jurassic. The original architecture of these environments is now obscured due to intense structurally deformation with many of the contrasting strata now structurally juxtaposed. This diversity in depositional environments resulted primarily from the extensional nature of the northeastern Gondwana margin during this period. The extension, driven by a series of rifting events, led to the formation and reactivation of horst and graben across the margin. This provided topography to the margin and divided the margin up into semiisolated depositional basins. As a result of this throughout the Permian to Middle Jurassic at any one time there were a wide range of depositional environments from shallowwater carbonate dominated environments, to basinal hemipelagic carbonate dominated environments, and to siliciclastic dominated basinal environments. These environments overlapped both spatially and temporally. This presentation presents a stratigraphic framework, based on integrated conodont, palynomorph, foraminiferal and ammonoid biostratigraphy, for interpreting the Permian to Middle Jurassic palaeogeography of Timor.
The gold mineral system: do we know what we don't know? T. Campbell Beresford^
McCuaig^
Stephen
W.
^Centre for Exploration Targeting, The University of Western Australia, (cmccuaig@cyllene.uwa.edu.au) Research into gold systems, be them epithermal Au, Porphyry Au, or Orogenic Au has largely focused on understanding the processes operating at the deposit to near-mine scales, so that we can better predict where similar processes may have occurred when exploring for analogues of these deposits. However, work on several Tier 1 Precambrian Au deposits (Boddington, Hemlo, Timmins, Val d'Or Camp, Kalgoorlie, Laverton district, Ashanti) has revealed that the largest deposits have often been affected by multiple periods of gold introduction/remobilisation. Moreover, between deposits in a single terrane (e.g. Wallaby, Sunrise, Granny Smith in the Laverton district; Kalgoorlie versus St, Ives in the Kalgoorlie area; Hemlo versus Timmins in the Abitibi-Wawa belt) the main period of gold introduction differs between deposits.
Given this observation, the question becomes: 'what made those particular blocks of lithosphere so well endowed in Au over time'. Answering this question takes us out of the deposit scale, where we can directly observe and sample the effects of geological processes more easily, and into the realm of the entire mineral system. Using a mineral system approach, one can define the key questions regarding the genesis of Au deposits that research should focus on in order to have the maximum impact on how we explore. If one breaks down the system to its simplest elements of (1) sources of heat, melts, fluids, solutes, (2) transport from source regions to site of deposition, and (3) mechanisms of concentration of metals at the site of deposition, the key questions that emerge strongly lean towards the source and transport problems. Future research needs to focus on designing experimental programs to constrain (1) the processes that control the source of melts and fluids (2) how metals partition between melts, fluids and minerals at different P, T, Xrock and Xfiuid, (3) how melts and fluids are physically transported from the mantle lithosphere through to upper crustal conditions. Only when these processes are more thoroughly constrained will we be able to derive more effective proxies in geoscience datasets to aid in the prediction of the location of Tier 1 gold deposits.
Rediscover Victoria in 3D Paul McDonald^ ^ GeoScience Victoria GPO Box 4440 Melbourne Victoria 3001 (Paul.A.McDonald@dpi.vic.gov.au) The Victorian Government is currently investing over $23 million into supporting the minerals and petroleum industry in Victoria. Building on the successful Victorian Initiative for Minerals and Petroleum (VIMP), which has seen over $32 milhon invested to date, are the Gold Undercover and Rediscover Victoria initiatives. Gold Undercover is a $9 million initiative which will deliver the new pre-competitive geoscience data, insights and techniques required to discover the potentially large undiscovered gold resources presently concealed under cover. More specifically Gold Undercover aims to accomplish increased investment in gold exploration in Victoria via; - Increased drilling and discovery rates - Increased investment in developing new gold mines - Job creation in provincial Victoria - Creation of new mining services businesses in provincial Victoria Rediscover Victoria is a new $5 million geoscience program to encourage minerals and petroleum exploration in parts of the State where little exploration has occurred to date. The initiative is made up of two key projects. continued next page... Australian Earth Sciences Convention 2008
173
174
ABSTRACTS alphabetically by surname of presenting author
The Rediscover Victoria Drilling project (RDV) will provide funding assistance to industry to encourage exploration drilling in greenfield areas. The RDV aims to promote the minerals potential to Victoria and speed-up the rate of discoveries The Rediscover Victoria 3D project will deliver a state-wide 3D geological framework required to stimulate the research and exploration communities in Victoria and help establish regional Victoria as a leading minerals and hydrocarbon producer. Specifically the project will develop a fully attributed 1:250 000 scale 3D model that integrates the onshore and offshore geology of the State. As such the model will provide a unique dataset on which to 'value-add'. For example geometrically constrained 3D simulations of complex geological regions will allow a better understanding of: 1. Plumbing networks associated with mineralisation 2. Interactions between CO2 injection sites, hydrocarbon accumulations and onshore groundwater resources 3. Heat flow and potential geothermal resources.
Age and Stratigraphic Constraints On The Evolution of Mega-Lake Bungunnia: Insights Into Plio-Pleistocene Climate Change In Southern Australia. Sandra McLaren\ Malcolm W. Wallace\ Brad Pillans^ Stephen J. Gallagher^ ^ School of Earth Sciences, University of Melbourne, Victoria, Australia, 3010 (mclarens@unimelb. edu. au) (mww@unimelb. edu.au) (sjgaU@unimelb. edu. au) ^ Research School of Earth Sciences, Australian National University, Acton, ACT, Australia, 0200 (brad.pillans@anu. edu. au) Modem and ancient lake sediments preserve a record of the effects of both climatic and tectonic change (Carroll & Bohacs, 1999, Geology v. 27, p. 99-102). Megalake Bungunnia in southern Australia, covering more than 40 OOOkm^, is one of the largest known palaeo- or modem lakes in an intracontinental setting. The formation and demise of Lake Bungunnia has been previously used to make inference on the nature and timing of PlioPleistocene climate cycles, including the onset of aridity in the Australian continent. However, the age and origin of the lake remain controversial and the stratigraphic architecture is poorly constrained. In part this is because the low average topography of the region means the lake sediments are only exposed in discontinuous outcrop, mainly along the modem river valley, and because of a general absence of useful dating material, such as fossil assemblages. The lake sediments comprise the Blanchetown Clay and the Bungunnia Limestone, a thin (l-3m) overlying lacustrine carbonate unit. A series of
Australian Earth Sciences Convention 2008
outcrops of Blanchetown Clay in the eastem portion of the Murray Basin allow the establishment of a regional Plio-Pleistocene stratigraphy and also the recognition of important regionally correlative units. We tie this stratigraphic framework to the time scale with new magnetostratigraphic age data. These data, from almost certainly the most complete section of Lake Bungunnia sediments exposed anywhere within the Basin, show that the Blanchetown Clay could not have been deposited any earlier than Gauss-Matuyama transition around 2.5 Ma. This is significantly younger than the 3.2 Ma age previously reported for the oldest Blanchetown Clay (An Zhisheng et al., 1986, Palaeo^ v. 54, p. 219-239). We use this stratigraphic and chronologic framework, together with geochemical, sedimentologic and biostratigraphic observations to make inference on the nature of climate cycles throughout the lake's history.
Fact-ites, Quizzicles and EarthCaching: The Geological Society of Australia Education and Outreach Initiatives. Where to from here? Greg McNamara^ ^ Geoscience Education and Outreach Services, PO Box 70 Buchan, Victoria, Australia 3885 (geoservices@geoed. com. au) The Geological Society of Australia has recognised for some time that many science teachers are not comfortable teaching the Earth and Beyond components of the curriculum. To address this problem the GSA has embarked upon an education and outreach program that provides plain English information for many of the topics covered in Earth and Beyond curricula in several highly engaging formats. Fact-ites are easy to understand, informative readings with easy to complete questions or activities based on the readings. They are photocopy ready and can easily be used as adjuncts to the teaching of Earth and Beyond topics by teachers with limited experience in these subjects. Quizzicles are web-based interactive games that are available in a variety of engaging formats. Each Quizzicle is based around a reading that is available in a separate window. Quizzicles provide clues, information about incorrect selections and scores and encourage the computer literate students of today to find out more about Earth and Beyond topics. EarthCaching is a GPS-driven educational adventure game in which people are the search engine and the planet is the teacher. Teachers and students who create Earthcaches leam a lot about their environment as they develop and submit their proposal. Teachers, students and members of the public who seek and find EarthCaches are rewarded by the experience and leaming that goes with it. Fact-ites, Quizzicles and EarthCaching will be demonstrated and their appeal to teachers and students analysed and discussed. Methods of
ABSTRACTS alphabetically by surname of presenting author
promoting these products will also be highlighted. Future developments in the GSA education and outreach program, including ideas for ongoing lYPE activities, will be presented and discussed.
The Teacher Earth Science Education Programme [TESEP]: A national scheme to assist teachers and help students discover Earth Science and associated career paths. Greg McNamara^^ Len Stevens \ Mike Fittall^
Altman ,
Jill
Esso Australia Pty Ltd 12 Riverside Quay, Southbank, Victoria 3006, Australia (jilL stevens @ exxonmobil com; mike, e.fittall @ exxonmobil com) Geoscience Education and Outreach Services, PO Box 70, Buchan, Victoria, Australia (geoservices @ geoed. com.au) ^Marden Senior College The purpose of TESEP is to enhance the quality of earth science teaching and learning in Australian schools and to assist in addressing the critical national shortage of young people in the trades and professions in the Energy, Minerals & Environmental Sciences industries. TESEP aims to raise the profile of Earth and Environmental Sciences (EES) in secondary schools to a level matching the strategic importance of these industry's to the Australian economy. TESEP aims to improve Year 7-10 Earth and Environmental Science teaching resource materials nationally and to run a series of two day "The Challenging Earth " Professional Development (PD) workshops for Years 7-10 secondary teachers. PD workshops will be run in multiple centres in each state/territory through 2008 and 2009, except for Western Australia, which will follow later. TESEP has the potential to improve the teaching of science nationally particularly Earth and Environmental Science in the current curricula junior to middle high school years 7 to 10. TESEP can increase the awareness of Energy, Minerals (^Environmental Science career options for trades and professions. This presentation will report on progress to date in establishing TESEP, funding the programme and the impact 2008 operations have had to date. Future plans and aspirations for TESEP will also be outlined.
Testing Deposit Models in the Eastern Goldfields Province, WA: The Geochronology Perspective Using Hydrothermal Monazite and Xenotime Neal J. McNaughton^ Noreen Vielreicher ^, David 1. Groves ^
M.
1 John de Laeter Centre of Mass Spectrometry, Applied Physics, Curtin University of Technology, n. mcnaughton@curtin. edu. au 2 School of Earth and Geographical Sciences, University of Western Australia Deposit models for hydrothermal ore systems are constantly being reassessed in the light of new information and ideas. Recent observations that the datable hydrothermal minerals monazite and/or xenotime are commonly associated with, and are petrographically coeval with, ore minerals in many hydrothermal ore deposits, coupled with technical developments in the in situ geochronology of these minerals, now provide a reliable timeframe of mineralization which can be compared with the evolution of the local to regional terrain. These techniques have been applied to a number of major lode-gold deposits in the Eastern Goldfields of the Yilgam Craton in WA. The results allow the timing of mineralization and other events to be compared between deposits and regions, and provide a robust assessment of most deposit models for a range of typical(?) Archaean lode-gold deposits in the Yilgam, and probably elsewhere. Not surprisingly, the new data support the widely held view from historical times (i.e. >10 years ago) that mineralization is late in the tectonic history of the terrains. Despite a variety of local structural and rock competency and chemical controls, gold mineralization in the Eastern Goldfields is confined to two relatively restricted time periods. These two gold epochs correlate with different terrains and do not appear together in a single terrain. Further, multiple mineralization events within one camp (e.g. Golden Mile and Mt Charlotte mineralization at Kalgoorlie) seem to occur within a paragenetic continuum and overlap in time (within the analytical errors of the age determinations). In situ U-Th-Pb geochronology of monazite and xenotime have been widely applied to dating metamorphism, early to burial diagenesis, magmatic events and detrital mineral grains in (meta)sedimentary rocks. Reliable geochronology of hydrothermal ore deposits can now be added to this list.
Australian Earth Sciences Convention 2008
175
176 ABSTRACTS alphabetically by surname of presenting author
Key Geochemical Parameters of the Regolith
Isotopic Tracers of Fluid Sources in the Lachlan Orogen
Kenneth G. McQueen^
Terrence P. MemaRh\ Richard A. Glen^,
^CRC LEME, Australian National University, ACT 0200 (Ken.McQuee @ Canberra, edu.au)
^ Geoscience Australia, GPO Box 378, Canberra, ACT, 2601, Australia (Terry.Mernagh@ga.gov.au) ^ Geological Survey of New South Wales, NSW Dept. of Primary Industries, PO Box 344, Hunter Region Mail Centre, NSW, 2310 (dick.glen@dpi. nsw.gov. au)
Geochemical data from the regohth are routinely used by mineral explorers to detect anomalous abundances of target and pathfinder elements. However, regolith geochemistry can also provide information on the origin, history and nature of the regolith, useful for understanding the context of element dispersion and for selecting appropriate geochemical samples. Modern geochemical surveys typically take a multi-element approach, but rarely is full value gained from the large amount of data collected. In many cases these data, combined with some additional analyses of key elements, can be used to: distinguish different regolith materials; determine parent rock type; estimate the degree of weathering and leaching of in situ profiles; and locate ferruginous zones and redox fronts, which are potential sites for accumulation/fixation of target and pathfinder elements. Elements with limited weathering mobility provide templates for identifying parent rock compositions (e.g. Ti/Zr, TiA^, Ti/Cr, Al203-Ti02Zr). Chemical changes during weathering involve progressive loss of Na"^, K"^, Ca^^, Mg^"^ (some Si"^^) and retention of Si^^ Al^"" and Fe^^ The K/Al and Mg/Al ratios provide a simple index for characterising different regolith materials where they are at different stages of mineralogical/chemical evolution on the path to end-stage regolith. The Chemical Index of Alteration (CIA = 100 x Al203/(Al203 + CaO + Na20 -h K2O) can quantify degree of rock weathering, but estimates the total history of chemical weathering including that already present in sedimentary rocks prior to further weathering. Although it does not give a direct measure of the in situ weathering of a particular regolith sample, it can be very useful for comparing weathering within profiles developed on a common rock type. Studies in western New South Wales have shown that fractionation of rare earth elements (particularly Ce/Nd ratios) can be used to evaluate the intensity of chemical weathering and leaching. A ferruginisation index based on Fe/Ti ratios (alternatively Fe/Al) of regolith samples through the weathered profile can usefully locate redox zones.
Australian Earth Sciences Convention 2008
A study of lead and sulfur isotopes from mineralised and sulfide-bearing rocks has been conducted across the Lachlan Orogen. When combined with other geologic and geochemical data, the stable isotope data provides information on (1) source of metals, (2) the pathways of hydrothermal fluids as they pass through the rock column, (3) temperatures of mineral deposition, (4) the importance of redox variations in mineral systems, and (5) guides for exploration. The plumbo-tectonic model of Carr et al. (Econ. GeoL, 90, 1467-1505, 1995) provides an indication of the relative timing of mineralisation and hydrothermal events in the Lachlan Orogen. Pb model ages generally correspond well with the orogenic cycles. Exceptionally young model ages may indicate selective leaching of radiogenic Pb from cmstal rocks. The presence of both mantle fluids (associated with igneous rocks) and cmstal fluids (dominant in basins) indicates that fluid mixing has occurred along faults and boundaries. Variations in sulfur isotopes can arise from changes in source, changes in temperature, and oxidation/reduction reactions acting upon the sulfur. This last process allows the sulfur isotopes to be divided into reduced and oxidised groups. The reduced signatures correlate well with the mantle fluids, while juxtaposed oxidised and reduced signatures elsewhere, indicate fluid mixing. In contrast, oxidised (magnetite-bearing) mineral assemblages are associated with intrusive rocks while reduced (pyrrhotite-bearing) assemblages are mainly associated with basins. The major mineral deposits generally occur at the boundaries between regions with oxidised and reduced signatures and are also associated with the larger regional faults. With a few exceptions, the major deposits in the Eastern Lachlan Orogen tend to be associated with magnetite-bearing assemblages and reduced sulfur isotope signatures implying a requirement for the involvement of (oxidised?) mantle fluids.
ABSTRACTS author
alphabetically by surname of presenting
Position of the end-Permian mass extinction level and Permian Triassic boundary in Australia Ian Metcalfe \ Robert S. Nicoll ^ R. J. Willink ^ ^ School of Environmental & Rural Science, University of New England, Armidale NSW 2351, Australia (imetcal2@une.edu.au) Earth and Marine Sciences, Australian National University, Canberra ACT 0200, Australia (bnicoll@goldweb. com.au) ^ Origin Energy Ltd, Ground Floor, South Tower, John Oxley Centre, 339 Coronation Drive, Milton QLD 4064, Australia Late Permian (late Changhsingian), Early Triassic Induan (Dienerian), and early Olenekian (Smithian) conodonts have been recovered from the Hovea Member of the Kockatea Shale in the exploration well Corybas-1, northern Perth Basin, Western Australia. Ongoing studies of the Kockatea Shale from other Perth Basin wells are providing additional conodont material that further refine the international calibration and correlation of the Australian Upper Permian - Lower Triassic. Based on the recovered conodonts, coupled with megaspore data and previously reported Cisotope, macrofossil and geochemical data, the Permian Triassic boundary (GSSP level) is placed in the lower part of the Sapropelic Interval of the Hovea Member of the Kockatea Shale, and the mass-extinction level at the Inertinitic-Sapropelic boundary within the Hovea Member. The presence of Clarkina jolfensis Kozur internationally calibrates the Australian endemic Protohaploxypinus microcorpus palynofloral zone and the basal part of the Sapropelic Interval of the Hovea Member as late (but not latest) Changhsingian age. The Permian-Triassic boundary, based on international calibration using conodonts, carbon isotope stratigraphy and new radio-isotopic dating, is placed in the lower part of the Kraeuselisporites saeptatus and Lunatisporites pellucidus Zones of Western and Eastern Australia respectively which corresponds approximately to a position low in the Saggitarius Sandstone of the basal part of the Rewan Group and equivalents in Eastern Australia.
Multiple gold events at Laverton, Eastern Goldfields Superterrane, W.A. John Miller\ Paul Henson^ ^Centre for Exploration Targeting/ pmd^CRC, University of Western Australia, Western Australia ^pmd'^CRC, Geoscience Australia, GPO Box 378, Canberra, ACT The role of early versus late-stage gold events, and the role of intrusions, has been the subject of debate in the Laverton region of the Yilgarn Craton, W.A. Structural correlation between the world class Wallaby and Sunrise Dam gold deposits has been integrated with a regional 3-D model. Multiple gold events linked to more than one stress field occur at Wallaby and Sunrise Dam, nearly all phases of veining are associated with gold, with major differences in endowment. The first phase of low grade gold at Sunrise Dam was synchronous with the deposition of the conglomerate at the Wallaby deposit. Initial low grade gold at Wallaby is syenite-associated, with major hematite-associated lodes having an inferred genetic relationship to the syenite (analogous to syenite-associated deposits in the Abatibi Belt, Canada). A later phase of major orogenic-style gold lode development was linked to NNW-SSE shortening, with the two deposits located on symmetrically opposed regional, right-stepping, contractional sinistral-slip jogs. The timing of this orogenic-style gold has previously been constrained, and is not within error of the age of the Wallaby syenite. Late-stage ultrahigh grade veins at Sunrise Dam, with tellurium and base metal associations, are associated with later dextral movement, by this stage Sunrise Dam was a regional dextral-slip dilational jogThe structural complexity reflects low strain, with deformation driven by fluid over pressure, probably in a weak far field stress field. Major periods of gold introduction at Wallaby and Sunrise Dam are not identical, which makes each deposit unique. The application of a single model for worldclass deposit formation is not valid, be it either "orogenic" versus "intrusion-associated" genetic models, or simple exploration targeting of contractional versus dilatant jogs (both are prospective). In reality, a spectrum of variable deposit-types have developed through geological time. Acknowledgements This paper is part of the Y4 pmd'^CRC program and is published with permission of the CEO.
Australian Earth Sciences Convention 2008
177
178 ABSTRACTS
atphafoetlcaliy by surname of preserttlng author
Stimulating Greenfields Mineral Exploration: The West Yilgarn Laterite Geochemistry Database Paul Morris \ Matthias Cornelius-, Ian Robertson^ ^ Geological Survey of Western Australia, 100 Plain Street, East Perth WA 6004 (pauL morris @ doir. wa. gov. au ^ Cullen Resources Limited, Unit 4/7 Hardy Street, South Perth WA 6151 (M Cornelius @ cullenreosurces. com. au) ^ CRC LEME/CSIRO Exploration & Mining, 26 Dick Perry Avenue, Kensington WA 6151 {Ian. Robertson @ csiro. au) Lateritic residuum represents, in large part, the in-situ weathering product of the underlying bedrock. As a sample medium, it is ubiquitous on the Yilgarn Craton, and the process of lateritization has been shown to sequester either elements of economic interest, or elements that point towards areas of mineralization. Furthermore, as much of this material is found as pisoliths, the mineralization fingerprint can be enlarged due to mechanical dispersion. In order to provide a regionallyextensive, comprehensive geochemical database suitable for mineral exploration, samples of ferruginous nodules or pisoliths ('laterite') collected at a nominal density of one sample every 70 km in the western part of the Yilgarn Craton and analysed for 53 elements. The 3142 samples making up this geochemical database not only confirm the presence of know mineral deposits but show that some areas of mineralization may extend beyond their currentlyknown extent. The database can also be used to identify lithologies typically associated with different styles of mineralization (e.g. greenstones and gold mineralization) which are not apparent from regional mapping due to poor exposure. In contrast to the strong lithological control on the distribution of some elements, others (e.g. Hg) are found in higher concentrations close to certain regional faults, indicating that these structures may be tapping buried mineralization. The use of a single sample medium, one laboratory, project-specific standards, and a multielement analytical suite means that the database is well suited to quantitative analysis related to mineral exploration for a variety of different mineral commodities. As government agencies are not restricted by jurisdictional boundaries such as exploration tenements, they are well suited to provision of such regional databases. The impact of the data release is shown by a three-fold increase in tenement pegging in the project area in the month following data release compared to the month preceding. Australian Earth Sciences Convention 2008
Mineral Exploration in New Zealand: New Research Framework and Tools Nick Mortimer\Tony Christie^ ^GNS Science, Private Bag 1930, Dunedin, New Zealand ^GNS Science, PO Box 30368, Lower Hutt, New Zealand New Zealand usually ranks fairly low on league tables of investment attractiveness based on perceptions of mineral potential. Some recent and ongoing research initiatives aim to improve New Zealand's appeal by supplying relevant geoscience research results and data to the mineral exploration community: REGIONAL GEOLOGICAL CONTEXT New Zealand's Paleozoic-Mesozoic terranes and batholiths are the continuation of the continental orogenic belts of eastern Australia, and New Zealand's Cenozoic volcanic belts are the prolongation of the Melanesian arc systems. Regional geological studies of specific trans-Tasman connections e.g. Paleozoic and Cretaceous igneous suites that host Cu-Mo-Au, Paleozoic terranes (mesothermal Au), and Miocene volcanics (epithermal Au, Ag) are being undertaken within GNS Science's six year FRST-funded Programme "Mineral Wealth of NZ and its EEZ". TARGETED PROSPECTIVITY STUDIES Regional mineral resource assessments (e.g. Coromandel 2001 and Northland 2007) highlight overall prospectivity to both explorers and local governments. Reports by GNS Science and Crown Minerals (e.g. Mesothermal Au 2002, and Epithermal Au, 2003) emphasise prospective areas specifically for gold deposits. DIGITAL DATABASES GNS Science databases include QMAP, a 1:250 000 digital geological map of New Zealand that provides a new information platform for prospectivity and area selection. MINMAP and PETLAB are web-accessible databases that provide mineral deposit information and geochemical and petrophysical analytical data direct to explorers. The Ministry of Economic Development's Crown Minerals unit also offers many reports and technical resources.
ABSTRACTS alphabetically by surname of presenting author
Widgiemooltha Mine Observations of a Type 1 Komatiite Nickel Deposits and Implications for Exploration. Peter Muccilli' ^Mincor Resources NL, Level 1, 1 Havelock Street West Perth 6872 The Widgiemooltha district has produced a total of 165KT of Ni Metal to Jan 08. Most of the current mines at Widgiemooltha show good correlation with a Type 1 Komatiite Volcanological geological model for nickel sulphides accumulation. Mincor now has been mining at Widgiemooltha since 2001. The following geological observations have been obtained at these mines; 1. The significant variations in minerahsation and dimension along the plunge of ore, interpreted as controlled by the primary volcanological ore environment. Examples of this primary control will be shown at our least deformed mine. 2. The varying degrees of structural modification and subsequent remobihsation of mineralisation, and how to 'see through' this subsequent modification to primary controls on ore. At each mine we can show the history from the initial discovery/geological model of an ore body through to today. The initial geological model, particularly the plunge, for the Mariners, Miitel and Wannaway mines were different when compared to the current understanding of these mines. As a result of point 1 and 2, the true size of these systems was not initially appreciated. The long exploration history of each these Widgiemooltha mines and the lessons learned is valuable for any explorer of Type 1 Nickel deposits.
High-Mg Monzodiorite-Tonalite ± Syenite Intrusions, Skarns, and Gold Deposits in The Eastern Goldfields Province, Yilgarn Craton, Western Australia. Andreas G. Mueller^ ^12a Belgrave Street, Maylands W.A. 6051 (andreas @ conceptual, net. au) Magnetite-series monzodiorite-tonalite and lesser kersantite and syenite intrusions constitute a distinctive high-Mg suite in the Eastern Goldfields orogen of the Archaean Yilgarn craton. The main suite (Mg# = 0.30-0.65, Cr = 35-350 ppm, Ni = 20160 ppm) formed by hornblende fractionation of monzodiorite magma sourced from mantle peridotite. High-Mg stock-dike complexes cut across regional folds and thrusts, and cluster along sinistral strike-slip faults. Along the Boulder-Lefroy Fault, they occur in the Golden Mile (1435 t Au) and in deposits at Kambalda. At Mt Shea, faulted quartz monzodiorite is replaced by Cu-Au epidote-magnetite skarns (0.5% Cu, 0.3 g/t Au) up to 40 m thick. Local postskarn sericite-ankerite schist is also mineralised with magnetite + pyrite -i- chalcopyrite (<0.62% Cu, 1.6 g/t Au). At Granny Smith (37 t Au) northeast of Kalgoorlie, a monzodiorite-granodiorite stock (2665+3 Ma) cuts across folds and E-dipping thrusts in greywacke. The stock is fractured and contains gold in sericite-dolomite lodes. Monazite-xenotime U-Pb (2660+5 Ma) and molybdenite Re-Os ages (2661+6 Ma) indicate mineralization shortly after granodiorite intrusion. At Wallaby (180 t Au) west of Granny Smith, dikes of monzonite and kersantite intrude folded and thrust-faulted conglomerate, overprinted by barren epidote-actinolite skarn forming a 600 m wide pipe. The skarn is intruded by syenite altered to muscovite + calcite. Biotite-calcite veins containing low-grade gold and silver cut across skarn and syenite. Structural relations and the U-Pb age of skarn titanite constrain intrusion-related gold to 2662+3 Ma. The main-stage gold ore forms sericite-dolomite lodes in thrust faults displacing skarn, syenite, and veins. Its molybdenite Re-Os age (2661+10 Ma) is within error of its monazite U-Pb age (2651+6 Ma).
Australian Earth Sciences Convention 2008
179
180 ABSTRACTS alphabetically by surname of presenting author
Dating high-grade metamorphic events in the Narryer Terrane by U-Pb SHRIMP analysis of monazite and zircon Janet R Muhling^ Ian R. Fletcher^ and Birger Rasmussen^ ^ Centre for Microscopy, Characterisation and Analysis MOW, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia (ianet. muhling @ uwa. edu. au) Department of Applied Geology, Curtin University of Technology, GPO Box U 1987, Perth, WA 6845, Australia Monazite is the chronometer of choice for deciphering the timing and duration of tectonometamorphic events. U-Pb SHRIMP analysis of both monazite and zircon from high-grade metasedimentary rocks has been used to constrain the P-T-t path of the northern part of the Narryer Terrane. The Narryer Terrane forms the northwestern portion of the Yilgarn Craton between the Youanmi Terrane and the Glenburgh Terrane of the Capricorn Orogen. The deepest part of the terrane now exposed is around Mukalo Creek, about 10-20 km south of the Errabiddy Shear Zone, which marks the boundary between the Narryer and Glenburgh terranes. Metamorphic assemblages of opx-grt-sil-qtz in metapelitic rocks indicate metamorphism at lower crustal conditions of ~800°C and 7-10 kbar. Dating of both monazite and zircon from pelitic rocks indicates that metamorphism occurred over an extended period from 2620-2660 Ma. Monazite from a kyanite-bearing quartzite preserves a similar age range (2590-2650 Ma), whereas zircons from the quartzite preserve detrital ages, in excess of 3.0 Ga. These data indicate that the Narryer Terrane experienced extended residence at lower crustal levels in the Neoarchaean, probably during its accretion to the Yilgarn Craton. Mineral coronas in pelitic rocks show that uplift of the Narryer Terrane initially occurred at high temperatures (~700°C), with coronas of cordierite forming between orthopyroxene and silhmanite, and pseudomorphous replacement of sillimanite by kyanite. Rims on monazite grains in these rocks record U-Pb ages of -2.0 Ga showing that uplift occurred during collision between the Narryer and Glenburgh Terranes. Zircons in the pelitic rocks do not record the uplift event, and neither do monazites from the quartzites despite replacement of sillimanite by kyanite. Care needs to be taken in interpreting the P-T-t paths of metamorphic terranes since different chronometers from different bulk compositions may record different parts of its history.
A Potential New MVT Province in Laos Ian R Mulholland^ ^Rox Resources Limited, PO Box 1167, West Perth WA 6872, Australia (imulholland@roxresources. com. au) A potential new Mississippi Valley Type (MVT) mineral province has been identified at Pha Luang in Laos. Exploration by Rox Resources has intersected ore grade lead-zinc mineralisation of the MVT style at a number of prospects. Soil sampling has outlined extensive zones of strong secondary mineralisation at surface, with soil values exceeding 10% Zn, 10% Pb and 100 ppm Ag in some locations. Mining of the surface oxidised deposits is being undertaken by a local Lao company, and Rox is exploring under joint venture for the deeper sulphide bodies. Oxide outcrops have been mapped over at least 15km of strike along the limestone sequence. Drilling at the Nam Yen prospect has returned intercepts such as 33 metres grading 2.7% Zn, 8.7% Pb, 19 g/t Ag, and 19 metres grading 3.8% Zn, 4.8%) Pb, 36 g/t Ag. The galena-sphalerite mineralisation is hosted in undolomitised brecciated limestone, with the sulphide replacing the fme grained carbonate breccia matrix. At the Pha Sod prospect drilling has intersected lower grade, but significant sphalerite, with intercepts of 28 metres grading 1.6% Zn, 0.4% Pb, 6 g/t Ag being typical, although exploration is still at an early stage. The mineralisation shows a number of classical MVT textures, including colloform and breccia textures. All sphalerite is visually of the lowiron variety, although electron microprobe analyses have not been undertaken. There is a strong structural control to the emplacement of mineralisation, although this work is still at an early stage.
ABSTRACTS alphabetically by surname of presenting author
What Drives Major Episodic Reorganisations of the Plate-Mantle System?
Provenance of Ophiolitic Sand: Comparison of Ancient and Modern Sand
Dietmar Mtiller^ Joanne Whittaker , Maria Sdrolias^
Melissa MurphY^ Ryan Portner\ Nathan Daczko\ Julie Dickinson^ and Shelley Allchurch^
^EarthByte Group, School of Geosciences, University of Sydney, Australia, NSW 2006, dietmar@geosci. usyd. edu. au A long-standing controversy in global tectonics concerns the ultimate driving forces that episodically cause major plate tectonic reorganizations. Proponents of "top-down" mechanisms argue that plates themselves drive instabilities of the plate-mantle system, whereas others have argued that major mantle overturns drive plate tectonic punctuations. The most prominent manifestation of this controversy is the HawaiianEmperor seamount chain bend (HEB). While there is ample evidence from hotspot trails, paleomagnetism, geodynamic models, and intraplate volcanism to support a mantle flow mechanism, the recent redating of bend initiation to -50 Ma correlates the HEB with major tectonic events from around the Pacific. Revised Pacific ocean-floor reconstructions suggest that subduction of the Pacific-Izanagi spreading ridge and subsequent Marianas/TongaKermadec subduction initiation may have been the ultimate causes of the HEB. Rapid subduction of the Pacific-Izanagi ridge, over a vast distance, may have triggered a chain reaction of tectonic plate reorganizations. With subduction of the PacificIzanagi ridge at 55 Ma, forces acting on the Pacific changed from ridge-push to slab pull, which changed Pacific absolute plate motions from northwest to west. Increased slab pull north of Australia, due to a westerly progression of the subducting Wharton Basin mid-ocean ridge, changed Australian absolute plate motion from northwest to north. A combination of Australian and Pacific plate motion changes between 53 Ma and 50 Ma then initiated both the Tonga-Kermadec subduction system and the Izu-Bonin-Marianas subduction systems. We suggest that the observed slowdown of sub-Pacific mantle flow at 47 Ma was due to progressive impediment of lateral sub-Pacific mantle flow by the descending slabs of the IzuBonin-Marianas and Tonga-Kermadec subduction zones. Our model emphasizes top-down mechanisms for major reorganizations of mantle flow patterns and plate motions. Fully dynamic mantle flow simulations are required to test this model.
^ Department of Earth and Planetary Macquarie University, Australia (mmurphy @ els. mq. edu. au)
Sciences,
Macquarie Island, located 1500 km southeast of Australia, is a sub-aerial exposure of Miocene oceanic crust/upper mantle situated within the oceanic basin in which it formed. The seafloor spreading related 'Finch Langdon Fault' juxtaposes upper mantle serpentinised peridotites, gabbro and sheeted dolerite dykes in the northern quarter of the island with volcanic rocks (pillow basalts, massive flows, hyaloclastites) that form the southern part of the island. Interbedded within the extensive volcanic sequences are ancient sandstones containing gabbroic clasts, indicative that gabbro was exposed at the mid-ocean ridge during active volcanism. We use the major and trace element composition of spinel and clinopyroxene in the sandstones to test if upper mantle was also exposed during active sedimentation at the mid-ocean ridge. We compare this data set with analyses of zircon separated from modern colluvium derived from the presently exposed upper mantle serpentinised peridotites, gabbro and sheeted dolerite dykes. Zircon was characterised for trace elements. Laser ablation ICP-MS ^^^U dating and Hf isotope ratios to determine the age and provenance of grains. Our preliminary analysis confirms that gabbro was exposed at the mid-ocean ridge during seafloor spreading. A lack of any peridotite signature in spinel and clinopyroxene grains suggests that it is unlikely that the upper mantle was exposed during deposition of the sandstones. We present new ^^^U - ^^^Pb zircon detrital ages that range between approximately 7.5 to 9 Ma (n = 84). The average ^'^Hf/^^'Hf isotope ratio of the grains is 0.283144 + 0.00004 (2o, n = 30). This corresponds to a range of sHf = 11.55 - 14.63 and TDM model ages averaging approximately 240 Ma, indicative of an inhomogeneous mantle.
Australian Earth Sciences Convention 2008
181
182 ABSTRACTS alphabetically by surname of presenting author
New Geophysical Constraints on the Extent of the Stawell and Bendigo Zones in New South Wales Robert J. Musgrave\ Michael Hallett^, Astrid Carlton^ Yvette Poudjom Djomani'^ ' Geological Survey of New South Wales, NSW Department of Primary Industries, PO Box 344, Hunter Region Mail Centre, NSW 2310 {rohert. musgrave @ dpi. nsw. gov.au) ^ Geological Survey of New South Wales (michael. hallett @ dpi. nsw. gov. au) 3 Geological Survey of New South Wales (astrid. carlton @ dpi. nsw. gov. au) 4 Geological Survey of New South Wales (yvette.poudjom. djomani @ dpi. nsw. gov. au) Interpretation of aeromagnetic imagery acquired during the Exploration NSW program led to a reconsideration of the role of the Governor Fault as a terrane boundary, and indicated that the Bendigo and Stawell zones continue northwards from Victoria into New South Wales. Fresh questions have arisen concerning the relationship between the Delamerian Stawell Zone and the Lachlan and Thomson orogens. New initiatives within the New Frontiers program of the Geological Survey of NSW have improved the definition of the Stawell and Bendigo zones in New South Wales through programs of gravity and teleseismic data acquisition. Wavelet edge analysis of the new gravity data has helped define the major bounding structures of the two belts, and teleseismic tomography has revealed the large-scale lower crustal and upper mantle terrane elements. Recognition of belts of negative magnetic anomalies within the Stawell Zone in New South Wales resembling those associated with gold prospects within the Victorian Stawell gold field has stimulated exploration interest. Gold in the Victorian Stawell Goldfields is associated with basalt domes and their mantle of deformed, pyrrhotitic black shales. Zones of high fluid flow in the black shales are associated with preservation of a reversed palaeoremanence in pyrrhotite, leading to the observed negative anomalies. Chloritisation has lowered the magnetic signature in the basalt domes. Within the NSW prospects, the negative magnetic anomalies are flanked by gravity highs, suggesting a similar association of black shales with zones of concentrated fluid flow on the flanks of chloritised basalt domes. This abstract is published with the approval of the Deputy Director-General, NSW Department of Primary Industries.
Potential Field Models of the Bancannia Trough - Koonenberry Belt System, NSW: Tectonics of a Rifted Arc. Robert J. Musgrave^ John Greenfield^, Yvette Poudjom Djomani^ Rosemary Hegarty"^, Stephen Dick^ ^ Geological Survey of New South Wales, NSW Department of Primary Industries, PO Box 344, Hunter Region Mail Centre, NSW 2310 (robert.musgrave@dpi.nsw.gov.au) ^ (john.greenfield@dpi. nsw.gov. au) ^ (yvette.poudjom. djomani@dpi. nsw.gov. au) ^ (rosemary. hegarty@dpi. nsw.gov. au) ^ (stephen.dick@dpi.nsw.gov.au) Together, the Delamerian Koonenberry foldand-thrust belt and the Bancannia Trough, with its Cambrian basement and 5-km-thick Devonian to Mesozoic fill, form a prominent paired system of NW-striking, high-amplitude features in gravity and magnetic imagery of north-western NSW. A series of detailed potential field models, informed by a deep seismic section and incorporating recent geological mapping, geophysical image interpretation, and wavelet edge analysis, has allowed the development of a 3D geological model for the paired belt, and stimulated revised interpretations of the Delamerian and Benambran orogenies in the region. Within the Bancannia Trough, a series of high-amplitude, long-wavelength magnetic anomalies result from large, buried sources with density and magnetic properties typical of intermediate to mafic igneous rocks. Draped over these is a volcanic sequence, apparently correlating with the Early to Middle Cambrian Gnalta Group (Mt Wright Volcanics), covered in turn by the Devonian basin. Modelling of the Koonenberry foldand thrust belt reveals a series of east-dipping thrusts which sole out on a 5-7 km thick, high-susceptibility feature, which we interpret as a magma chamber. The Koonenberry fault dips SW at about 45°. Both the aeromagnetic expression and the inversion model of the magnetic basement of the Bancannia Trough closely resemble features of the Central Volcanic Zone of the North Island of New Zealand, and we infer a similar rifted arc setting for the Bancannia Trough in the Early to Middle Cambrian. Compression in the Koonenberry beh appears to have included a stage of transpression on the Koonenberry Fault. Bending of the fault at the Cobham Kink Zone occurs opposite a gap in the chain of magnetic anomalies marking large volcanic edifices; rheological weakness at this part of the backstop may have caused the development of the kink zone, in an analogous fashion to the bend in the Alpine Fault of New Zealand. This abstract is published with the approval of the Deputy Director-General, NSW Department of Primary Industries.
ABSTRACTS alphabetically by surname of presenting author
Archean plate tectonic processes in southwest Greenland
What Does The Regional Setting of The Voisey's Bay Nickel Deposit Tell Us About Where To Find Similar Deposits?
John S. Myers John S. Myers Applied Geology, Curtin University of Technology, Perth, WA 6845 (myersm@iinet.net.au) Plate tectonic processes resulted in the assembly, thickening and tectonic and metamorphic reworking of continental crust throughout Archean time since -3.8 Ga. Previous studies have interpreted the Godthaabsfjord region of southwest Greenland as being composed of several units of Archean continental crust that evolved independently before being assembled during the late Archean. This hypothesis is essentially founded on U-Pb zircon ages of igneous and metamorphic events with little information on tectonic processes. In contrast, this presentation illustrates the plate tectonic processes that led to crustal thickening and stabilization of continental crust. Disruption of the well preserved igneous stratigraphy of the Fiskenaesset and Nunataarsuk anorthosites demonstrates late Archean subhorizontal translation, imbrication and stacking of thrust sheets, similar processes to those well known from Proterozoic and Phanerozoic orogenic belts. The best preserved Ivisaartoq and Isua greenstone belts, mainly derived from basaltic volcanic rocks, indicate similar processes at ~ 3.1-3 Ga and ~ 3.83.7 Ga. These tectonic events were accompanied by the generation of large volumes of tonalite and the emplacement of tonalite as sub-horizontal sheets along active thrusts over thousands of km^. This led to the layered nature of the Archean gneiss complex of Greenland that was essentially sub-horizontal until subsequendy folded and refolded. In contrast, Proterozoic and Phanerozoic plate tectonic processes generally led to continental growth that was primarily linear, with magmas generated and emplaced into relatively narrow, steep to subvertical belts of continental accretion hundreds of km wide and thousands of km long. Sub-horizontal translation in thrust belts was generally limited to these narrow orogens and only the margins of adjacent cratons. The rock record of southwest Greenland indicates that the tectonic processes and resulting structures that formed between -3.8 and -2.8 Ga were similar to those of more recent Earth history, although there was a change in the nature of crustal growth.
Applied Geology, Curtin University of Technology, Perth, WA 6845 ( myersm@iinet.net.au) The Voisey's Bay nickel deposit of Labrador is associated with troctolite in an anorthosite-granite batholith. The diverse magmas were generated in a lithosphere-scale fault zone, - 5 0 km wide and >1000 km long, within the continent of Laurentia. Repeated episodes of sinistral transtension along the fault zone triggered pulses of mantle melting, and facilitated the rise of magmas to middle and upper crustal levels between -1365-1140 Ma. In Labrador, where this fault zone intersected a Paleoproterozoic orogen, the magmas extended -250 km along the orogen and formed the anorthosite-granite Nain batholith. The Voisey's Bay nickel deposit is located in the centre of the fault zone, near the centre of the batholith close to the former continental suture within the Paleoproterozoic orogen. Space for the rising magmas was produced by obhque extension within shear zones followed by brittle fracturing, stoping and cauldron subsidence. In detail, magma was emplaced in pulses related to cycles of alternating upward pressure that formed cone sheets and funnel-shaped intrusions followed by downward collapse that formed ring dykes and tabular magma chambers. At Voisey's Bay, these processes transported magma with Ni-Cu-Co sulphides, already concentrated in a lower magma chamber, upwards along cone sheets and ring dykes to be injected into an upper magma chamber. The prerequisite for a Voisey's Bay type of mineral deposit appears to be a continental, lithosphere-penetrating, fault zone in which tectonic movements led to repeated generation of large volumes of mantle-derived magma. The active fault zone provided the conduits by which the magmas rose in pulses over tens of millions of years, successively fractionating, melting existing crust and rising to the middle and upper crust through increasingly hot and dry host rocks. A close analogue of the Nain batholith is the Kunene complex in the Congo craton. This complex forms a batholith similar in structure, composition, size and age, and is a likely location for Voisey's Bay type mineral deposits.
Australian Earth Sciences Convention 2008
183
184
ABSTRACTS alphabetically by surname of presenting author
Global Significance of Stable Carbon, Sulfur and Hydrogen Isotope Signals Together With Higher Plant Derived Components of Sedimentary Organic Material From the Permian/Triassic Boundary. Birgit Nabbefeld\ Kliti Grice\ Richard Twitchett^, Arndt Schimmelmann^, Roger Summons"^, Lindsay Hays^, Michael Bottcher ^ Curtin University of Technology, Perth, Australia, (B.Nabbefeld@ exchange, curtin. edu.au) (K. Grice @ curtin. edu. au) ^ University of Plymouth, Plymouth, UK ^Indiana University, Bloomington, USA Massachusetts Institute of Technology, Cambridge MA, USA ^ Institut fur Ostseeforschung Warnemiinde, Rostock, Germany Near to the Permian/Triassic (P/Tr) boundary approximately 252 million years ago one of the most severe mass extinctions in Earth's history occurred (Benton & Twitchett, 2003, Trends in Ecology and Evolution, V. 18., p. 358). Volcanism, methane release from the melting of gas hydrates, bolide impact, global anoxia, oceanic overturn of stagnant deep ocean waters, and outcropping of hydrogen sulphide are mechanisms invoked and debated. Several stable isotope excursions ( • ^^Cbiomarkers, • ^^Ckerogen, •^'^Spynte) occur near this boundary and suggest a global perturbation of carbon and sulfur cycles (e.g. Grice et al., 2005, Science, v. 307, p. 706; Fenton et al., 2007, EPSL, v. 206, p. 230). Stable hydrogen isotope (DD or D/H) data of kerogen (of comparable type and thermal history) from different P/Tr sections globally (China, Western Australia, East Greenland and Spitsbergen) can provide information on paleoenvironment and the source of the organic matter (e.g. Lis et al., 2006, Organic Geochemistry, v. 37, p. 342, Schimmelmann et al. 2006, AREPS, v. 34, p. 501). A dramatic negative excursion in DD of kerogen (ca. 35 %c) is evident in several of the sections and correlates with parallel excursions in D^^C of kerogen and S^'^S of pyrite. The significance of these changes along with DD/D^^C of biomarkers will be presented in terms of source/facies, paleoenvironment and the extinction event itself. Throughout the same period of time, significant changes are observed in the type and abundance of selected biomarkers, particularly those derived from woody plants. Aromatic compounds such as dibenzothiophene (DBT), dibenzofuran (DBF) and biphenyl (BP) are of particular interest. Recent data from samples from Greenland and Western Australia show high abundances of DBT, DBF and BP just before the extinction horizon (e.g. Fenton et al., 2007, EPSL, v. 206, p. 230). We have proposed a common lignin source for these Australian Earth Sciences Convention 2008
components. We found a dramatic decrease in the abundance of these compounds just above the extinction level which coincides with a sudden decrease in S^'^S of pyrite due to marine redox changes (Grice et al., 2005, Science, v. 307, p. 706). It is suggested that two processes are operating here, namely a change in redox conditions and the extinction and/or sea level transgression which could account for the absence of woody material. Further data from other sections (Spitsbergen, Western Canada) will help establish whether these processes are represented globally.
Bio-activity in the 3.46 Ga ferruginous Marble Bar chert, Pilbara, Western Australia M. Nedachi^ 'Kagoshima
University
It has been debated among researchers on the Fe precipitation in the 3.46 Ga Archean Marble Bar ferruginous chert. We discuss on the bio-activity in the chert to understand the Fe precipitation. We examined the fresh core of Marble Bar chert drilled by Archean Biosphere Drilling Project. The ABDP#1 core of the Marble Bar chert is composed of two kinds of chert; banded sedimentary chert and hydrothermal quartz vein (or dyke). The former is composed of rhythmical bands, rich in Fe oxide, rich in Fe carbonate, and free from Fe. In the ferruginous chert, numerous hematite and/or magnetite grains are accumulated as small spherical to euhedral grains in the central portion of quartz crystal, which shows botryoidal texture, resembled that of modern microbe mat of benthic coccoid cyanobacteria in appearence. SFM image shows microbe like cell connecting with and enveloping hematite grains in the botryoidal quartz, resembled also modern Fe bacteria. The carbon Is X-ray photoelectron spectra (FSCA) acquired from banded cherts contain the peak of C-C and C-H bonding. Furthermore, the Raman spectrum obtains the peaks derived from organic carbon. The Raman spectrum image reveals the heterogeneous distribution of organic carbon in the botryoidal quartz, and suggests that the quartz originated from silica gel or amorphous silica. The C isotopic ratios suggest the inhabitation of microbe. The fluid inclusions suggest the boiling at rather shallow depth. Although the carbon content of ferrugious chert is very low, synthesis of quartz from Fe-C bearing silica-gel shows the depletion of carbon during implantation, suggesting the leaching of organic carbon from Fe rich Marble Bar chert during migration and diagenesis. The evidences suggest that the microbe remain is from Fe bacteria, which precipitated iron oxides to form ferruginous chert, using hydrogen ion under solar ray (or using dissolved oxygen gas).
ABSTRACTS alphabetically by surname of presenting author
Shallower Submarine Ecosystem at 2.72.8 Ga, Pilbara, Western Australia M. Nedachi^ Y. Nedachi^ ^ Kagoshima University ^Kagoshima Immaculate Heart University The 2.7-2.8 Ga shallower submarine ecosystem is discussed, using the fresh core of 2.77Ga Mt Roe basalt (ABDP#6) and the 2.74 Ga Tumbiana Formation (ABDP#10), Pilbara, Western Australia, in the standpoint of the late-Archean environment. Two fresh and consecutive cores are studied mineralogically, paleomagnetically and organo-geochemically, to give new and more detailed insight into this concern. The Mt Roe Basalt core is characterized by the alternation of subaerial basaltic lava, clastic sediments (conglomerate to mudstone) rich in organic carbon, and carbonaceous hydrothermal alteration zone overlain by sediments. The Tumbiana Formation core is composed of basaltic lava overlain by stromatolite member of shallow sediments. The basaltic lava in both cores erupted mainly on subaerial zone. The basalt lavas show the downward (reversed?) paleomagnetic direction. The magnetic mineral in the basaltic lava is mainly primary magnetite coexisting with ilmenite, but the minor flow unit contains only secondary magnetite oxidized from ilmenite, which might be the weathering production. The same paleomagnetic direction through core succession suggests that the weathering occurred subsequendy after the eruption and magnetized. The absence of hematite suggests, however, that the oxidation level in atmosphere should not be so high. The carbon isotopic composition of kerogen from two cores ranges mainly from -40 to -60 permil with minor evidence from -20 to -30 permil. The isotopic evidences and occurrences of organic carbon suggest the followings; (1) microbes inhabited in the shallow seafloor as well as hydrothermal system in shallow submarine, (2) cyanobacteria (stromatolite) inhabited in the seafloor near coast in the Mt. Roe Basalt and Tumbiana Formation, suggesting that the environment shallow depth were oxic, (3) sulfide reducing/oxidizing bacteria could also inhabitate around the hydrothermal system, (4) methanogene could inhabit in Mt. Roe hydrothermal vein, producing methane to make the fluid strongly reduced the country rocks, and ,however, (5) methanotroph could inhabit using the oxygen produced by cyanobacteria. These evidences suggest that oxic environment was completed at the top of the seawater column in 2.7 to 2.8 Ga and saturated in oxygen to be transferred to the atmosphere near coast.
Stromatolites as a record of the biodiversity and physiology of early Earth Brett Neilan^ Malcolm Walter^ Roger Summons \ Brendan Bums^ ^ Australian Centre for Astrobiology at The University of New South Wales and Massachussetts Institute of Technology Hamelin Pool at Shark Bay, Western Australia contains a wide variety of unique stromatolite structures and is considered to be one of the most important stromatolite sites in the world. This geological novelty is a result of different microbial communities colonising various regions along the intertidal desiccation gradient. Despite their evolutionary significance, little is known about the associated microbial communities. By employing culture dependent and cultureindependent methods, we report the dis covery of a wide range of microorganisms associated with these biosedimentary structures, many possessing physiologies consistent with their hypersaline habitat. There are no comparable reports combining these methodologies in the survey of cyanobacteria, bacteria, and archaea in marine stromatolites. Based on this study, a wide diversity of bacteria, cyanobacteria and archaea have been detected. The community was dominated by organisms of the cyanobacterial genera Synechococcus, Xenococcus, Microcoleus, Leptolyngbya, Plectonema, Symploca, Cyanothece, Pleurocapsa, and Nostoc. We also found levels of diversity corresponding to novel sequences that are unrelated to those of any other cyanobacteria, and sequences that seem to represent early branches in the cyanobacterial tree. In addition, we report the discovery of potentially free-living Prochloron. Other bacterial isolates and clones from the stromatolite sample clustered into 7 phylogenetic groups: 0P9, OP 10, Marine A group, Proteobacter, Low G+C Gram-positive, Planctomyces and Acidobacteria. The presence of sequences corresponding to members of halophilic archaea from the divisions Euryarchaeota and Crenarchaeota, and methanogenic archaea of the order Methanosarcinales has also been demonstrated. This is the first report of such archaeal diversity being present in this environment. Re-applying the molecular data to optimise culturing, several novel isolates have been obtained, including new species of archaea. The production and potential communal distribution of adaptive features, such as osmolytes, has also been characterised and the molecular basis for coping with fluxes in temperature, desiccation and UV will be presented. In combination with stable lipid signature data, the molecular diversity and various microbial physiologies provide a picture of life on early Earth that has been associated with these
continued next page..
Australian Earth Sciences Convention 2008
185
186 ABSTRACTS alphabetically by surname of presenting author
geological structures. Stromatolites are rare biological systems that present unique opportunities to address fundamental questions in fields ranging from microbial ecology, evolution, chemical biology, functional genomics, and biotechnology. This study provides a better understanding of the dynamic balance between microorganisms and their environment in the formation of these living rocks.
Early evolution of Earth and Moon A.A. Nemchin^ R.T. Pidgeon^
^ Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth, WA 6845 The Moon and the Earth appear to have developed through similar stages in the first 500-600 m.y. of their histories, although the subsequent evolution of both planets cannot be more different. During the first stage both the Moon and the Earth experienced global differentiation of their mantles as a result of crystallisation of their respective Magma Oceans. However, it is still unclear if the terrestrial and lunar magma oceans were both formed after the separation of the two planets as a result of a giant impact, or global differentiation of Earth took place prior to the impact. Both sides of the argument rely on isotopic constraints that are often model dependant (e.g. ^'^^Nd-^'^^Nd systematics that suggests differentiation of the Earth within 30m.y. of planetary accretion, while requiring nearly 200m.y for complete crystallisation of the lunar magma ocean). Crystallisation of the lunar magma ocean was accompanied by differentiation resulting in the formation of reservoir enriched in incompatible elements called KREEP. Our recent results on the UPb systems of lunar zircons have shown that the KREEP reservoir formed at 4420+10 Ma. The final product of fractionation of the magma ocean on Earth is less evident. Early studies of inclusions in the ancient zircons from the Jack Hills (Western Australia) suggest that this reservoir was granitic in composition. The age of the oldest Jack Hills grains indicates that the enriched source was present on Earth at least at 4360+10 Ma (or may be even at 4.4 Ga). It has been proposed that the final stage on early evolution of both planets is characterised by a short period of intense meteoritic bombardment at about 3.8-3.9 Ga. This is evident on the Moon from the resetting and primary ages of variety of rocks obtained using different isotopic systems with relatively low closure temperatures. There is a general lack of evidence of this cataclysmic event on Earth where it is implied from observations on the Moon and the close proximity of the two planets. However, our investigations of resetting patterns of lunar zircons that both the Moon and the Earth experienced several periods of intense bombardment during their early history, rather than a single late cataclysm. Australian Earth Sciences Convention 2008
New Geochronological Constraints on Sedimentation in the Georgetown Inlier: Correlations With The Mount Isa Inlier. Narelle Neumann , George Gibson , Ian Withnall^ Peter Southgate, Alexis Lambeck^ ^Geoscience Australia, GPO Box 378 Canberra, ACT 2601, Australia (Narelle.Neumann@ga.gov.au; George. Gibson@ga.gov.au; Peter. Southgate@ga.gov. au; Alexis.Lambeck@ga.gov.au) ^Geological Survey of Queensland, Department of Mines & Energy, Block A, 80 Meiers Rd, Indooroopilly, QLD 4068, Australia. (ian.withnall@dme.qld.gov.au) The Georgetown Inlier contains Proterozoic metasedimentary rocks, volcanic rocks and granites which were metamorphosed at -1560-1550 Ma (Bain and Draper, 1997, AGSO Bulletin 240). Metasedimentary packages include the Etheridge and overlying Langlovale Groups. The Etheridge Group is interpreted to be 6-11 km thick, with the metamorphic grade increasing eastwards. Parts of the Etheridge Group have been correlated with the high-grade Einasleigh Metamorphics to the east. New U-Pb SHRIMP data on detrital zircons from stratigraphic units within the Etheridge Group have been used to determine maximum depositional ages and provenance characteristics for these sedimentary packages. Stratigraphic units within the lower Etheridge Group have maximum depositional ages of -1695 Ma, consistent with previous constraints from associated intrusive rocks. These ages suggest that lower units are equivalent to the Calvert and lowermost Isa Superbasins of the Mount Isa Inlier. Provenance spectra for lower units of the Etheridge Group have large proportions of late Archaean-early Palaeoproterozoic ages, significantly different to the age distributions for the Calvert and Isa Superbasins. Stratigraphic units higher within the Etheridge Group have younger maximum depositional ages of -1650 Ma, indicating that they are time-equivalents of the upper Isa Superbasin. Provenance spectra for these units are also similar to those of sedimentary rocks of the Isa Superbasin. In combination with previous work, these new geochronological constraints provide a detailed stratigraphic event framework for the Georgetown Inlier, and allow comparisons and correlations with other Proterozoic terranes.
ABSTRACTS alphabetically by surname of presenting author
Keys to the Production of Eastern Yilgarn Au deposits: Chemical and Structural Architecture Controls on Sites of Fluid Mixing P. Neumayr , J.L. Walshe , K. Petersen 3 ^ pmd^CRC, CET, University of Western Australia (pneumayr@cyllene. uwa. edu. au) ^ pmd'^CRC, CSIRO Mining and Exploration, ARRC, Perth, WA6151 (john.walshe@csiro.au) ^ pmd'^CRC, CET, University of Western Australia (kjpeters @ cyllene. uwa. edu. au) Whilst the structural analysis of an area reveals sites which are suitable to host gold deposits for example in dilational sites, it produces false positives with sites which did not have the right fluid chemistry, i.e. the fluid did not contain gold or gold complexes were not destabilized. It is argued here that combining the structural architecture with the chemical architecture has the potential to reduce the search area significantly more then with simple structural analysis alone. A number of Eastern Goldfields gold deposits are located at sites where the hydrothermal alteration assemblages change over short distances (e.g., deposits in the St. Ives gold camp, Kanowna Belle and Wallaby deposits). Typically the chemistry changes from reduced and acid hydrothermal alteration (e.g., muscovite, paragonite, pyrrhotite, arsenopyrite) to oxidized and alkaline assemblages (e.g., pyrite, magnetite, hematite, phengitic mica). At a regional scale, oxidized assemblages relate to porphyry intrusive complexes situated in subsurface domal structures as indicated by seismic profiles and gravity data. Reduced fluids are likely to be associated with deeply-tapping, transcrustal structures. At the chemical gradient between the two hydrothermal cells, fluid - fluid interaction occurred and gold complexes were destabilized. At a deposit scale (e.g., Victory-Defiance), stable isotope and mineral assemblage mapping in 3D identified distinct subvertical, oxidized fluid flow at intersections of E-W trending structures and subvertical NW- or NNW-trending structures, all of which are outlined by porphyry intrusions. Shallowly SW dipping structures typically contain reduced hydrothermal fluid flow distal to the oxidized upflow zones. Gold deposition occurred proximal to the oxidized upflow zone at sites with clear evidence of both reduced and oxidized hydrothermal fluids (i.e. mixing zone). At an ore shoot scale, mutual overprinting relationships between oxidized and reduced alteration assemblages indicate that both systems were synchronous.
The Permian Conodont biostratigraphy of Western Australia - an update Robert S. Nicoll ^, Ian Metcalfe ^ ^ Earth and Marine Sciences, Australian National University, Canberra ACT 0200, Australia (bnicoll@ goldweb.com.au) ^ School of Environmental & Rural Science, University of New England, Armidale NSW 2351, Australia (imetcal2@une.edu.au) Earlier reports on the Permian conodont biostratigraphy of Western Australia have documented faunas from the Canning Basin (Noonkanbah Formation) and Carnarvon Basin (Callytharra, Coyrie, Wandagee and Coolkylia formations) that ranged in age from the Late Sakmarian to the Roadian. New studies have now documented additional Permian conodont faunas from the Perth Basin (Beekeeper Formation) and from the Canning Basin (Nura Nura Member of the Poole Formation, from throughout the Noonkanbah Formation, in the Lightjack Formation and from the Kirkby Range and Cherrabun Members of the Hardman Formation). These faunas range in age from the Late Sakmarian to the Wuchiapingian. In the high latitude faunas of the Western Australian basins the conodont fauna has been dominated by the genus Vjalovognathus with only occasional occurrences of the genera Hindeodus and Mesogondolella and only a single occurrence of the genus Sweetognathodus in the Noonkanbah Formation. In the lower latitude conodont faunas from Timor, Pakistan, Tajikistan and Nepal/Tibet, the generic and species diversity of the conodont faunas is greater and this has been attributed to warmer water temperatures. These cold water Tethyan faunas have been sparsely document from localities in the Salt Range of Pakistan, the Pamirs of Tajikistan, the Himalayas of Nepal and Tibet, and from Timor and the western margin of Australia. This study has been able to recognize a total of 9 species of the Genus Vjalovognathus based on prominent morphologic trends. Several of the key taxa have yet to be recognised in localities outside Australia.
Australian Earth Sciences Convention 2008
187
188 ABSTRACTS alphabetically by surname of presenting author
The Cambro-Ordovician, the Centralian Superbasin (Part 2) and transGondwanan Seaways. Robert S. Nicoll^
open flow of marine waters across Gondwana may have been only periodic, but it played an important part in the Ordovician geologic history of Australia.
Transport and Deposition of Colloidal Gold in Saprock Fractures.
^ Earth and Marine Sciences, Australian National University, Canberra ACT, 0200, Australia hnicoll&gokhveh. com, an
Ryan Noble^ Robert Hough^ Elizabeth Grenik\ Martin Saunders^, Peta Clode^
The Centralian Superbasin was originally defined to only include the Neoproterozoic fill of the Amadeus, Georgina, Ngalia and Officer basins. However, during the Cambrian, sedimentation was more widespread over central Australia than in the Neoproterozoic, with marine sedimentation occurring in the Early Cambrian in the Amadeus, Georgina, Ngalia, Officer, Wiso, Daly, Ord, Bonaparte and Arafura basins. However, during the Early Cambrian the superbasin started to fragment with the commencement of a temporally extensive tectonic event. SHRIMP dating of detrital zircons and metamorphic zircon growth in the Harts Range Complex has demonstrated that the Amadeus and Georgina basins were contiguous and that they lay either side of a deep intracratonic rift in which sediments, coeval with those in the present remnant basins, accumulated. Further west a similar situation is found between the northern margin of the Amadeus Basin which thickens northwards and the southern margin of the Wiso Basin, which thickens southwards, with the added complication of the Ngalia Basin which is interspersed between the two. If a similar arrangement existed between the Amadeus-NgaliaWiso as existed between the Amadeus and Georgina, there is little current evidence to support it. Reworked Late Cambrian and Ordovician conodonts in the Devonian Pertnjara Group indicate that deeper water environments existed to the north of the current structural Amadeus Basin boundary, but no indication of a deep rift is found in the poorly outcropping Arunta Block. If such a rift did exist it would have to be north of the Ngalia Basin as the Cambrian sediments in that basin are similar to those of the Amadeus and are mostly shallow marine. The possibility exists that there may have been as many as 3 trans-Gondwanan seaways that crossed parts of what became the Australian Plate. The northern-most of these is represented by Cambro-Ordovician sediments of the Arafura Basin. The second possible seaway links the Georgina, Wiso, Daly, Ord and Bonaparte basins. The Georgina-Wiso-Daly-Ord-Bonaparte seaway could have been intermittently active from the Early Cambrian to the mid-Ordovician. The southern-most of the seaways, the Larapintine Seaway, extending from the eastern Gondwanan margin through the Amadeus and Canning Basins and on across the North or South China Blocks to the Palaeo-Tethys Ocean. For the Larapintine Seaway, at least, the
^CSIRO Exploration and Mining (CRCLEME), PO BOX 1130, Bentley, Perth, (ryan.noble@csiro.au) Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Crawley, Perth.
Australian Earth Sciences Convention 2008
The Golden Virgin pit, south of Southern Cross in Western Australia, is a small gold deposit where primary mineralisation occurs as small, high grade quartz veins, blanketed by 30 m of weathered cover. The veins near the base of the regolith contain visible primary Au in the quartz (up to 1 mm) and have weathered fracture surfaces lined with different generations of secondary iron oxides, clays and sulphates together with an exceptionally rich population of supergene Au crystals (500 |um). Gold is normally bright in Back Scattered Electron microscopy; however, some of the supergene Au grains are darker grey, being nanoplates partially transparent to the electron beam. These single crystals also occur with a separate population of 100 nm and smaller single crystals of nanoparticulate colloidal gold. The specific process(es) leading to the reduction of the gold colloid and therefore the precipitation of the gold in this environment is not known. Supergene gold is Ag-poor, commonly closely associated with halite crystals and sometimes intergrown with barite. This supports the premise that pure gold was precipitated from the saline and slightly acidic groundwater, with the occurrence indicating rapid gold deposition, on the order of days or less. Inorganic laboratory experiments have confirmed this process. This form of gold is likely elsewhere in the world where similar conditions exist.
Microbially Induced Sedimentary Structures - Signs of Life in Archean to Modern Sandy Marine Settings. Nora Noffke^ ^Old Dominion University, (nnoffke @ odu. edu)
Norfolk,
VA
23529;
Fundaments of Archean paleontological research are the reef-like, solid stromatolites, and filigrane body fossils of tiny bacterial cells preserved in chert. Those structures and fossils are abundant in aquatic paleoenvironments, where mineral precipitation and cementation fostered the formation
ABSTRACTS alphabetically by surname of presenting author
and preservation of those features. However, siliciclastic shallow-marine settings also include signs of ancient life. Here, "microbially induced sedimentary structures - MISS" indicate the former presence of microbial mats constructed by benthic cyanobacteria and/or bacteria. The structures differ significantly in appearance from stromatolites, and 21 main types have been found so far. MISS rise exclusively from the interaction of microbial mats with the physical sediment dynamics that governs clastic environments. Investigations conducted in modern tidal flats document how benthic microbiota respond to various hydraulic conditions by biostabilization, or baffling, trapping and binding. This bacterial interaction with the sediments causes structures such as 'wrinkle structures', 'erosional remnants and pockets', 'multidirected ripple marks', and many others. The MISS occur not only in the modern, but fossil structures have been found in equivalent tidal and shelf deposits of all Earth ages including the early Archean. The 2.9 Ga old Pongola Supergroup, South Africa, contains outstanding examples for MISS that record a multitude of microbial mats colonizing different facies zones of an ancient tidal flat. The same microbial mats (constructed by benthic cyanobacteria) occur today in modem tidal areas as well. Because of the striking similarity between the ancient and modern MISS, the 2.9 Ga old Pongola Supergroup may include perhaps the oldest cyanobacteria in the fossil record.
New Perspective on the Lunar Cataclysm from Crater Density Populations Marc Norman^ Charles Lineweaver ^ ^ Research School of Earth Sciences, Australian National University, Canberra ACT 0200 Australia Crystallisation ages of impact melt breccias from the near-side equatorial regions of the Moon show a pronounced clustering between 3.75 and 3.95 billion years. This age distribution was unexpected and produced competing hypotheses for the early impact flux in the inner Solar System. A currently popular idea is that the impact flux spiked dramatically at about 3.9 Ga. In this iate heavy bombardment' scenario several of the nearside lunar basins formed within a relatively brief interval of time (200 million years). A late cataclysmic bombardment would have significant implications for Solar System dynamics perhaps involving migration of the outer planets. Alternatively, the impact flux may have declined steadily with relatively small fluctuations since formation of the Moon. In this scenario older impact deposits were destroyed and/or buried by more recent events. We have evaluated the long-term lunar impact flux using crater density populations preserved on ejecta deposits of large basins. This analysis provides strong evidence for a steep cratering flux early in the stratigraphic sequence of lunar basins but the implications for changes in the cratering flux through time depends on the absolute
ages of lunar basins, which are not well established. A late cataclysm would be strongly supported if the South Pole-Aitken (SPA) basin, stratigraphically the oldest basin on the Moon, has an absolute age not much older than the younger basins (i.e. 4 Ga). Older assumed ages for SPA (e.g. 4.4 Ga or 4.2 Ga) produce cratering flux curves indicating an early heavy bombardment, and weaker evidence for a late cataclysm. Better constraints on the absolute ages of stratigraphically intermediate basins such as Nectaris are critical for evaluating the late cataclysm hypothesis.
Mapping Mineral Alteration Associated with Onshore Hydrocarbon Seepage using ASTER and Hyperion Data Yulia Novikova^ Thomas Cudahy^, Simon Wilde^ and Simon Lang^ ^ Curtin University of Technology, Perth, (yulia.novikova@ postgraduate.curtin.eduMu) ^ CSIRO Exploration and Mining, Perth, WA Woodside Energy Ltd, Perth, WA
WA
Previous studies suggested that hydrocarbonrelated alteration can be mapped through changes in mineralogy generated by near-vertical migration of hydrocarbons leading to the development of secondary carbonate, pyrite, uranium, elemental sulphur, magnetic iron oxides and sulphides; bleaching of red sandstones and clay mineral alteration. To test it we investigated field samples and remote sensing data collected from the study area located in Al Qarqaf arch between Murzuq and Ghadames basins in Western Libya which is under exploration by petroleum geologists and where subsurface hydrocarbons are known from drilling and seismic data. Field samples were collected from outcropping sandstones and limestones from both potentially altered areas above known hydrocarbonbearing field and the background areas as well as nearby wells. Surface samples collected over the potentially altered areas show fracturing and veining. The analysis using an ASD spectrometer, XRD and SEM showed the presence of kaolinite, calcite, dolomite, pyrite and ferrous silicate/carbonate in the potentially altered area with iron oxide and calcite as a background. ASTER and Hyperion data were collected from over the study area to see if these minerals could be detected with current operational satellite systems as a potential tool for onshore hydrocarbon exploration. Of particular importance are the issues of spectral and radiometric resolutions. Pre-processing for ASTER involved correction for additive effects, including aerosols in the VNIR bands and instrument cross-talk effects in SWIR. Pre-processing of Hyperion data involved characterisation of the detector array using statistical methods which located and removed bad detector continued next page.. Australian Earth Sciences Convention 2008
189
190
ABSTRACTS aiphabeticaily by surname of presenting author
elements. Next step removed systematic column noise. Bad bands were also determined and culled to leave as residual 190 bands of the original 242 bands for a 255 pixel swath. This radiance sensor data were then reduced to apparent surface reflectance using the log-residuals technique. Mineralogical information extraction for both ASTER and Hyperion was based on spectral band combinations that target diagnostic mineral absorption features, including those of hematitegoethite, ferrous silicates/carbonates, kaolinite and calcite/dolomite as well as water associated with soils/rocks. The results of the ASTER processing showed that it was moderately useful for mapping some mineral groups including carbonates, kaohn group, ferrous and ferric iron and silicates/carbonates but was not able to detect precise mineral composition of each group. The results of Hyperion processing showed that kaolinite can be identified more confidently compared with ASTER but the poor radiometric resolution in the 2.3 - 2.4 nm region made it difficult to detect carbonate composition. The interpreted altered area over the known hydrocarbon reservoir is associated with kaolinite and ferric oxide in the northern part, carbonate with ferrous iron in the south and strong water absorption within carbonate rocks located between these areas. More work is being done to understand the relationship of this water to the hydrocarbon seepage and the role of fluid chemistry, especially REDOX and pH.
Tracing Paleo-Seismic Events in the Eastern Mediterranean (Turkey & Israel): U-Series Dating and Stable Isotope Studies Of Co-Seismic Carbonate Veins. Perach Nuriel\ I Tongue Uysal^ Gideon Rosenbaum^ Ram Weinberger^, Volkan Karabacak^ Suzanne D Golding^ ^ Earth Sciences, The University of Queensland, QLD, Australia 4072 (p.nuriel@uq.edu.au; t. uysal@uq. edu. au; g. rosenbaum@uq. edu. au; s.golding@uq. edu. au) ^ Geological Survey of Israel, 30 Malkhe Israel St., Jerusalem, Israel 95501 (rami@geos.gsi.gov.il) 3 Eski^ehir Osmangazi University, Department of Geological Engineering (karabacak@ogu.edu.tr) The challenge of dating and identifying fault movement is essential for understanding plate tectonic dynamics and earthquake reoccurrence. Here we present preliminary results from a study on the active plate boundary zone of the Dead Sea Fault Zone System (DSFZ) and the East Anatolian Fauh Zone (EAFZ). These faults are seismically active but direct information on the timing of fault initiation and prehistoric earthquakes is limited and controversial. We sampled carbonate veins of co-seismic Australian Earth Sciences Convention 2008
fissures from three key localities along the central EAFZ in Turkey (SW Maras), and the northern and southern DSFZ in Israel (Qiryat-Shemona and Barak Faults, respectively). All samples are directly related to fault movement as indicated by field structural relationship. We sampled carbonate veins from fault planes with clear slickenlines indicators in SW Maras, Turkey. In northem Israel a systematic and widespread banded carbonate vein system that strikes perpendicular to major fault planes suggests several distinct episodes of fault movement resulting in extensional vein opening, followed by accumulated carbonate precipitation. We have also sampled carbonate minerals from tension gashes and other asymmetrical features from southern Israel. While the U-series dating results are used for constraining the timing of carbonate minerals precipitation, mineralogical investigation (SEM and CL studies) will confirm the authigenic nature of these minerals, thus providing a robust record of fault movement. In addition, stable isotope studies (oxygen and carbon) will also provide important information about the role and origin of such earthquake mobilized fluids related to major earthquake events.
Ophiolite in the Eoarchaean (>3700 Ma) Isua supracrustal belt (Greenland): A 41 year-old debate Allen P. Nutman^ Clark R.L. Friend^ ^ Institute of Geology, Chinese Academy of Geological Sciences, 26 Baiwanzhuang Road, (nutman@bjshrimp.cn, Beijing, China crlfriend @ yahoo, co. uk) Hindering the identification of Precambrian ophiolites is that increasingly back in time, diagnostic lithological and structural features related to ophiolite formation become obliterated during metamorphism and deformation by unrelated younger superimposed tectono-thermal events. Within the most scanty and hard to interpret Eoarchaean geological record, maximum diligence is required to establish the presence of an ophiolite complex - given the significance for understanding Earth's early geodynamics. It is 41 years since the first proposal of an ophiolite assemblage in the Eoarchaean Isua supracrustal belt (Kurki & Keto, 1967 - report lodged at the Geol. Surv. Denmark and Greenland). But most recendy. Fumes et al. (2007, Science, v. 315, p. 1704) proposed that they had found a plagiogranite cutting a sheeted dyke complex in the western end of the Isua supracrustal belt, and claimed 'A vestige of Earth's oldest ophiolite'. We have seen the outcrops figured in Science. The 'plagiogranite' is a late discordant quartz vein cutting more deformed strongly foliated compositionally-layered amphibolites of equivocal origin - which Fumes et al. claimed as sheeted dykes. At another outcrop, figured as 100% sheeted
ABSTRACTS aiphabeticaiiy by surname of presenting author
amphibolites contain a -0.5 m thick concordant layer of quartzo-feldspathic schist. These are not contenders for plagiogranite and unequivocal 100% sheeted dyke complex. The part of the belt studied by Fumes et al. is a package of mostly strongly deformed amphibolites with island arc basalt chemistry (Polat & Hofmann, 2003, Precamb. Res. v. 126. p. 197), in which relict volcanic pillows and gabbroic texture are preserved. These are interleaved with highly magnesian dunites and harzburgites whose chemistry shows them to be mantle rocks, and with banded iron formation / chert (with rare 3715 Ma volcanic zircons). This interleaved assemblage is intruded along its eastern edge by 3715 Ma tonalite. It is discussed if this assemblage is Earth's oldest ophiolite.
Geochemical Evidence for the Development of a Fully-Oxygenated Atmosphere-Oceans And Modern-Style Ecosystems By -3.5 Ga
H. Ohmoto\ M. Hoashi^ Y. Watanabe\ D. Bevacqua\ E. Altinok^ T. Otake\ M. Mobilia\ 1. Johnson^ ^ NASA Astrobiology Institute and Dept. of Geosciences, Penn State University, University Park, PA 16802 USA (hqo@psu.edu) Center for the Promotion of Frontier Science, Kagoshima University, Kagoshima, 890-0065, Japan Current popular models of the early biosphere postulate extremely slow evolution of Hfe and the environment until ca. 2.5 Ga ago: the dominant organisms in the oceans were anaerobic (e.g., S- and Fe-oxidizing bacteria; methanogens); the land surface was mosdy sterile; the atmosphere remained H2- and CH4-rich and 02-poor; and the oceans remained O2- and S04^" -poor and Fe-rich. However, various types of data obtained from our recent investigations of cores from the Archaean Biosphere Drilling Project (ABDP) and other Archaean rocks, are difficult to explain by the popular evolution models. Such data include (but are not restricted to): (1) the absence of massindependently-fractionated sulphur isotopes (MIF-S) in major sedimentary formations; (2) the abundance of primary hematite crystals, and the distinct signatures of Ce and Y anomalies, in Algoma-type banded-iron-formations (BIFs) and associated submarine volcanic rocks that formed in deep oceans; (3) the occurrence of hematite-rich paleosols (laterites); (4) the occurrence and isotopic compositions of organic matter in paleosols; (5) the behaviour of redox-sensitive elements in the products of subaerial weathering (paleosols) and submarine weathering (altered submarine basalts); (6) the occurrence of red beds; and (7) the mineralogy, chemistry, and isotopic compositions of
black shales and carbonates (e.g., C and N of organic matter; S in sulfides and sulfates; Fe in sulfides, oxides and carbonates; redox-sensitive elements). Our new data are better explained with scenarios that include the early development (by -3.5 Ga) of: modern-style microbial ecosystems (consortiums of aerobic and anaerobic microbes, such as cyanobacteria, sulfate reducing bacteria, methanogens, and other microbes) in the oceans and on land; an O2- and C02-rich and CH4-poor atmosphere; and Fe- and H2S-poor, and O2- and SO4 -rich, oceans that hosted local euxinic basins, much hke today.
Possible Generation of MIF-S During Hydrothermal Alteration of Organic Rich Sediments. Hiroshi Ohmoto^ Yumiko Watanabe^
^ Penn State Astrobiology Research Center & Dept. of Geosciences, The Pennsylvania State University. University Park, PA 16802 USA (yumiko @ geosc.psu. edu) The presence of mass-independently fractionated S-isotope (MIF-S) signatures in pre-2.4 Ga sedimentary rocks, contrasting to the general absence in younger rocks, has been regarded by many investigators as the most conclusive evidence for the GOE (Great Oxidation Event) -2.4 Ga ago. This is because photochemical reactions of volcanic SO2 by UV in an 02-free atmosphere have been thought as the only mechanisms to create MIF-S. However, our discovery of the absence of MIF-S in major Archean sedimentary formations casts serious doubt on this model. We analysed -100 samples recovered from the NASA Astrobiology Biosphere Drilling Project (ABDP) in the Pilbara district. Western Australia. These samples represent a -150 m section of a lacustrine sandstone/shale unit (the 2.76 Ga Hardey Formation), a -180 m section of a marine shale/sandstone unit (the 2.92 Ga Mosquito Creek Formation), and a -100 m thick jasper/black-chert unit and an underlying -30 m thick black-shale unit (the 3.46 Ga Duffer Formation). Sedimentary rocks with strong MIF-S signatures by previous and this studies have the following characteristics: (a) a high concentration of organic-C (>1 wt%); (b) highly matured (altered) kerogen (H/C ratios <0.1); (c) an abundance of carbonates with unusually low d'^C values (<-8%o); and (d) strong hydrothermal alteration signatures (enrichment of Zn and Cu). In contrast, one or more of these characteristics are absent in samples with no MIF signature. Together with our recent discovery of large MIF-S signals (up to 2.1%o) in products during thermochemical sulphate reduction (TSR) experiments, we suggest that MIF-S signals in pre2.4 Ga sedimentary rocks may have created during early diagenesis of organic-rich sediments.
Australian Earth Sciences Convention 2008
191
192 ABSTRACTS alphabetically by surname of presenting author
Breccia Mechanics as an Explanation for Extreme Geochemical Micro-Gradients and Fluid Mixing in the Genesis of IronOxide-Cu-Au Deposits Oliver N . H . S . \ Williams, P J . \ Cleverley, Mark, G. \ Keys, D.L. \ Blenkinsop, T.G.^ ^ EGRU, School of Earth & Environmental Sciences, James Cook University, Townsville, Australia ^ CSIRO Division of Exploration & Mining, Kensington, Australia Geochemical zonation in the breccia-hosted Ernest Henry iron-oxide-Cu-Au deposit of the Proterozoic Mt Isa Block occurs in an oscillatory fashion at micro-scales and irregular to broadly concentric fashions at broader scales. Oscillatory zoning includes alternations between arsenical- and non-arsenical pyrite with no concomitant variation in S isotopes, and variations in the S, As, and CI contents of extremely unusual apatites, the latter pattern being mimicked in district-scale breccia pipes. Fluid inclusions analysed to date in the deposit are insufficiendy spatially or temporally constrained to confidently point towards fluid mixing, but span a broad range of compositions indicating a very diverse range of fluids was involved in ore genesis, from granite or mantlederived through to basinal brines (Kendrick et al., 2007). The oscillatory zoning suggests large fluctuations in S and As supply to the sulfides, which could be achieved either by pressuredependent changes in speciation (e.g. due to fluid pressure pulsing accompanying brecciation) or fluid mixing. Neither process is well modelled by thermodynamic data for As in sulfides or apatite for which the pressure dependence of solubility is poorly constrained. However, mass balance equations and geochemical models can emulate ore assemblages by fluid mixing whereas fluid-rock reactions by sulfidation and carbonatization explain neither the paragenesis nor the zoning patterns. Although the likely difference in viscosity and wetting character between S-rich and S-poor mineralizing fluids would inhibit fluid mixing, the ore assemblage represents the matrix to a milled breccia. We suggest that fluid mixing was achieved by the dynamics accompanying fluidized breccia behaviour, with cyclical pressure changes allowing ingress to two or more fluids and fragment collisions allowing mixing of the fluids in a natural geological ball mill.
Australian Earth Sciences Convention 2008
The Emergence of Steady-State Plate Tectonics in Dynamic Mantle Models Craig O^Neill^ ^ GEMOC, Department of earth and Planetary Science, Macquarie University, Sydney, NSW, coneill@els. mq. edu. au A fundamental criterion for a successful plate tectonic simulation is the reproduction of steady spreading rates and regular plate behaviour. Additional criteria include asymmetric subduction zones, plausible ridge migration and realistic interaction of subducting slabs with the transition zone. However, high Rayleigh number convection is typically erratic and chaotic. The development of plate-like motions require highly viscous surface boundary layers, and a plastic deformation mechanism. However, convection with such ingredients is, under most circumstances, highly time-dependent. Inclusion of mantle phase transitions constrained by mineral physics, most notably an endothermic transition 670km, exacerbates the problem, causing punctuated mantle exchange between the upper and lower mantles. Given the non-linearities in the Earth-system, it is fairly remarkable that anything approximating steady-state behaviour occurs at all. Part of the resolution of this problem lies in incorporating realistic mantle structures. Previous work has shown that the inclusion of a low viscosity asthenosphere contributes to steady spreading rates by minimizing viscous sublithospheric dissipation. This has the carry-on effect of producing large (Pacific-scale) plate widths, as well as regular spreading rates. Here we show that the interaction of descending slabs into the transition zone exerts a fundamental control on the surface dynamics of plates. The viscosity change at 670km, as well as the buoyancy effect of the phase transition, impede the dynamics of subducting plates, which at the surface results in the reproduction of such features as asymmetric subduction and slab rollback. We suggest many features characteristic of plate tectonics are, at least in part, a function of mantle structure.
A Spectrum of Hadean Geodynamics From Diamond Stability Constraints. Craig O^Neill^ ^ GEMOC, Department of earth and Planetary Science, Macquarie University, Sydney, NSW, coneill@els. mq. edu. au Recent work has shown the coexistence of diamond inclusions in felsic derived zircons. This is problematic, as shallow felsic magma chambers should not be conducive to diamond stability. Most recent examples of diamond inclusions in zircon come from ultra-high pressure massifs in Kazakhstan, where diamond replaced the original
ABSTRACTS alphabetically by surname of presenting author
graphite. The most plausible geodynamic scenarios for conversion of graphite->diamond in igneous zircons are either subduction, sagduction (ie. some undisclosed vertical tectonic process), or involvement in a whole-scale mantle overturn event, as has been postulated for the Archaean. Here we present simulations for a number of these scenarios, and track the PT conditions of entrained zircons through their history. We summarize the key features of each geodynamic model, and discuss plausible styles of Hadean dynamics based on diamond-stability constraints.
Two New lODP Paleoceanographic Drilling Opportunities in the Timor Sea: Late Quaternary Paleoceanography and Tracking Sea Level change from the Late Miocene Bradley Opdyke^ ^Research School of Earth Sciences, ANU, ACT 0200 (Bradley.Opdyke@anu.edu.au) Research in and around the Timor Trough over the past decade has opened up several new, exciting and unique opportunities for ocean drilling. The Timor Trough started to form and deepen in the Latest Miocene. At this time carbonate platforms started growing on the Australian side of the Trough margin. The steady subsidence and buildup of the "Sahul Shoals" has resulted in carbonate platforms that are 400 to 600m thick and cover an area of 10,000 square km. Like many carbonate platforms these probably only have significant growth phases during high stands of sea level. Because of the relatively high subsidence rates found here this could be a good place to test at the "dipstick" model for the relationship between sea level change and carbonate platform growth A second opportunity for coring exists in a small embayment between these carbonate build-ups in an area called the "Cartier Trough". The Cartier trough cuts at into the Australian shelf edge at roughly right angles from the main Timor Trough. The eastern side of this little basin is protected from the rapid currents which flow down the Timor Trough. This, combined with tidal flows spilling off the shelf have resulted in a spectacularly rapid accumulation here of hemipelagic sediments continental slope depths. Coring this would give us a brilliant paleoceanographic/paleoclimate record surface and thermocline depth waters for the late Quaternary, including the time interval when Indigenous Australians were first crossing the Timor Trough to this continent.
Archean Lithospheric Mantle: Formation, Composition and Today's Refertilised Remains. Suzanne Y. 0'ReillY^ W.L. Griffin^ Graham Begg 1,2 GEMOC ARC National Key Centre, Dept of Earth and Planetary Sciences, Macquarie University, NSW 2109, Australia (sue.oreilly@mq,edu,au; bill.griffin@mq.edu.au) ^ Minerals Targeting International PL, 17 Prowse Street, West Perth, 6005, Australia (graham, begg @ bigpond. com) Archean subcontinental lithospheric mantle (SCLM) is distinctive in its highly depleted composition, common stratification, and unique rock types absent in younger SCLM. Was the Archean mantle formed in a different way in a distinctive tectonic regime? What is the composition of original Archean mantle and how much persists today? The "typical" Archean mantle composition used by geochemists is derived mainly from xenoliths in kimberlites from the SW Kaapvaal Craton and Siberia. However, most such "typical" Archean xenoliths have experienced repeated metasomatism, leading to a progression from dunite/harzburgite through to "fertile" Iherzolite. Similar refertilisation processes can be studied in situ in peridotite massifs (eg Western Norway, Lherz), showing the Iherzolites to be due to melt infiltration into dunite/harzburgite protoliths. These depleted rocks are poorly represented in the published record; this bias partly reflects collection of rocks useful for P-T studies, but also has a geological basis. High-resolution tomography of Archean cratons shows high-Vs volumes surrounded by zones of lower Vs. The low-Vs parts can be modelled using "typical" garnet Iherzolite compositions, while the higher-Vs volumes require much more depleted rocks. In detail, kimberlites avoid the high-Vs regions, biasing "mantle samples" toward the metasomatised zones. Seismic tomography suggests this material still underlies the bulk of Archean cratons to depths of 150-200 km. Hf-isotope data on zircons show that much Proterozoic crust has Archean protoliths, suggesting underlying SCLM also was originally Archean. Seismic tomography shows high-Vs roots, requiring depleted compositions and low geotherms, under many such areas. Re-Os isotopic data for the underlying mantle preserve Archean signatures. This suggests progressive reworking of original buoyant Archean SCLM, rather than secular changes in the mechanisms of SCLM production. Seismic tomography suggests that >50% of existing continental crust is underlain by relict Archean SCLM, modified to varying degrees. This implies a much larger volume of originally Archean crust than currently accepted, and hence very high early crustal growth rates.
Australian Earth Sciences Convention 2008
193
194 ABSTRACTS
alphabetically by surname of presenting author
Titanium-zircon Minerals - Using Geoscience in Western Australia to Ensure Future Resource Extraction
Input of geomorphic and regolith mapping to the Interim Biogeographic Regionalisation for Australia (IBRA)
W R Ormsby^ M J Freeman^
Colin Pain^
^ Geological Survey ofWA, Department of Industry and Resources, 100 Plain Street, East Perth, WA 6004 (warren.ormsby@doir.wa.gov.au) Mineral Titles Division, Department of Industry and Resources, 100 Plain Street, East Perth, WA 6004
^CRC LEME, % Geoscience Australia, PO Box 378, Canberra ACT 2601 (colin.pain@ga.gov.au)
Western Australia has been a world leader in the production of titanium minerals (rutile, ilmenite and leucoxene) and zircon for over 50 years. In 2006, WA accounted for 29% of world production for rutile, 20% for ilmenite, and 35% for zircon. With downstream processing, exports for 2006-07 were valued at $1.41 billion. The Swan Coastal Plain dominates production, with two main centres in the BunburyCapel and Eneabba regions, about 200 km south and 240 km north of Perth respectively. Mineralization is within Pliocene to Holocene beach or nearshore dune deposits at three broad altitudes related to the present coastline, and two older higher sea-level still-stands. The titaniumzircon minerals presumably were derived from the underlying Mesozoic sediments of the Perth Basin. Contrary to expectations, age dating suggests that the ultimate source of most of the mineralization was not the adjacent Yilgarn Craton. With the co-operation of industry, the Geological Survey of Western Australia has mapped all known significant titanium-zircon mineralization on the southern Swan Coastal Plain. This identified areas that: - should be set aside for future mining (Strategic Mineral Resource Protection Areas), - are effectively sterilized (no longer restrict land use options), and - with exploration potential that may contain mineral deposits. The Swan Coastal Plain is currently undergoing rapid residential and industrial development. By informing all stakeholders of the locations of potential mining areas, the mapping of titanium-zircon mineralization has the potential to reduce future land use conflicts, and facilitate sequential land use planning. Appropriate planning measures are being implemented to ensure the sustainability of the titanium-zircon minerals industry in Western Australia.
Australian Earth Sciences Convention 2008
The Interim Biogeographic Regionalisation for Australia (IBRA) divides the Australian continent into 85 bioregions. 404 sub-regions have now also been defined Australia-wide based on major geomorphic features in each bioregion. The bioregions and sub-regions are the reporting unit for assessing the status of native ecosystems, their protection in the national reserve system and for use in the monitoring and evaluation framework in the Australian Government's current Natural Resource Management initiatives. The latest version is 6.1 [http://eied.deh.gov.au/parks/nrs/ibra/version61/index.html]. IBRA Version 6.1 consists of two datasets: - IBRA bioregions, which is a broad-scale regionalisation; and - IBRA sub-regions, which are more localised and homogenous geomorphological units in each bioregion. Recently, a revised map of the Jennings and Mabbutt (1977) Physiographic Regions of Australia has been prepared for the Australian Soil Resources Information System (ASRIS). The revision was carried out by digitising the original map and then overlaying it on the Shutde Radar Terrain Model (SRTM), which has a resolution of 90 m. The first step was to adjust the original boundaries to more closely reflect the landforms as depicted on the SRTM. This initial revision was then passed to state agencies for revision in light of more detailed information held at the state level. The final revision will be level 2 of the 6-level ASRIS hierarchy. This paper will assess the contribution the new map of physiographic regions can make to the IBRA regions, and look at a mapping hierarchy and other matters relating to scale, mapping and land unit characterisation. Jennings, J.N. and Mabbutt, J.A. 1977. Physiographic oudines and regions. Australia: a Geography, Jeans, D.N. (Editor), Sydney University Press, 38-52.
ABSTRACTS alphabeticaUy by surname of presenting author
Prospectivity Analysis in Action: The Auzex Resources Ltd. (AZX) Story as Applied to Granite Related Mineral Systems in Eastern Australia and New Zealand. Greg Partington^ ^Auzex Resources Limited The business of mineral exploration has changed in the last five years with mergers and acquisitions reducing the number of experienced mineral exploration companies. In addition most major mining companies still prefer to depend on acquisitions to replace and grow their companies. Consequently, few significant new mineral resource discoveries have been made in the last few years, while demand for metals such as gold, molybdenum and tungsten has increased significantly. The greatest value for investors in mineral exploration is created when new mineral resources are discovered. However, the discovery of new mineral resources is based on probability of about 1 in 3000, which makes the discovery of new mineral resources a rare event. Therefore for any company to be successful at the exploration end of the value chain they have to be able to increase their chances of success. This can be done by assessing the probabihty of occurrence of a commodity through efficiendy integrating and statistically analysing the large volumes of historical data, including mineral occurrence data, geology and geochemistry, that have been collected by previous mineral explorers in a region. Spatial data modelling is a rapidly developing predictive technique that is increasingly being used in geology. There are a growing number of mineral exploration companies who now believe that by using such modern statistical techniques and state of the art ore deposit models it is possible to add the greatest value to mineral assets and increase the probability of discovery of new mineral resources. Auzex Resources, who are an Australian Mineral Exploration company, are an example of such a company. The company integrated a large amount of historic geological information with a new deposit model to develop a national scale and regional scale prospectivity models for the East Coast of Australia and the West Coast of New Zealand to assess the potential for new discoveries. Tenements were acquired over the most prospective of these areas in Eastern Australia and New Zealand and field data checking carried out to assess the validity of the prospectivity models. To date seven prospects have been drilled, one has advanced to feasibility level and three others are at the resource development stage.
Morphological, Depositional and Temporal Controls on Sulfur Isotopes in Pyrite from the Hamersley Basin, Western Australia Michaela A. Partridge ^, Suzanne D. Golding^ Kim A. Baublys^ Elisa Young^ ^Earth Sciences, University of Queensland, QLD 4072, Australia (m.partridge@uq.edu.au) Pyrite in sedimentary facies of the late Archean and early Paleoproterozoic Hamersley Basin in Western Australia can be grouped into distinct isotopic populations that share common morphological, depositional and temporal characteristics. These results indicate that sulfide paragenesis is significant for interpretation of late Archean and early Paleoproterozoic multiple sulfur isotopes. Depositional environment is also important although this distinction is less pronounced in the early Paleoproterozoic than it is in the late Archean Late Archean fine grained pyrite from deep, presumably anoxic environments has positive correlations between and A^^S. They display proportional variations in the magnitude of each variable, potentially reflecting a mixed sulfur source comprising both positive A^^S atmospheric sulfur and -zero A^^S terrestrial sulfur (cf Kaufman et al., 2007, Science, v. 317, p. 900). Alternatively, moderate d^^S fractionations may also correspond to low positive A^^S values, possibly due to greater mixing with terrestrial sulfur. Fine grained pyrite from a late Archean platform environment has negative d^^S and positive A^^S that suggest microbial sulfate reduction of previously oxidised, positive A^^S atmospheric sulfur. Archean pyrite nodules comprise a further isotopic population with low negative A^^S and more variable (positive and negative) S^'^S. This may suggest these nodules were formed by microbial sulfate reduction in a depositional environment sufficiently oxidised to allow preservation of atmospherically derived negative A^^S sulfate. Thus an oxidative sulfur cycle was established by 2.6 Ga in near shore regions. In the early Paleoproterozoic, there is less distinction between pyrite morphologies, as fine grained, nodular and layer parallel pyrite from a deeper water environment has a restricted range of ^^S values and near zero or negative A^^S values that may reflect both seawater and hydrothermal sulfur sources. Regardless of morphology, pyrite from an early Paleoproterozoic platform environment trends towards modern sulfur isotope values that are consistent with the transition from an anoxic to oxic atmosphere.
Australian Earth Sciences Convention 2008
195
196 ABSTRACTS alphabetically by surname of presenting author
The Yamarna Shear Zone, NE Yilgarn Craton, AustraUa: Geometry, Kinematics, Constraints & Implications. MJ. Pawlev^ S.S. Romano\ M.T.D. Wingate^ ^Geological Survey of Western Australia, PO Box 1664, Kalgoorlie, WA, 6433, Australia. (mark.pawley @ doir. wa. gov. au) The Yamarna Shear Zone (YSZ) in the NE Yilgarn Craton is a crustal-scale, NNW-trending structure that can be traced along strike on aeromagnetic images for almost 300 km. A seismic survey across the Eastern Goldfields Superterrane suggested that the YSZ is east-dipping, listric, and extensional, flooring into a detachment at a depth of 35 km, similar to the terrane-bounding Laverton Tectonic Zone and Ockerburry shear system (Goleby et al, 2004, Tectonophysics, v. 388, p. 119133). The Mount Venn greenstone belt, located in the footwall on the western side of the shear zone, is dominated by upright folding, with axial-planarparallel, high-strain zones. A central zone, between the Mount Venn and Yamarna greenstone belts, comprises layered and foliated granites that contain lenses of greenstones. A granite from this zone with a U-Pb zircon SHRIMP age of 2662 ± 4 Ma, and sub-horizontal lineations and C-S-C relations, indicates dextral strike-slip shearing. The eastern zone comprises sheeted granite and greenstones — mainly metasedimentary rocks and metabasalts. Minor metamorphosed felsic volcanic rocks are preserved as "boudins" along the strike of the belt. Layer-parallel shear zones have sub-horizontal lineations, and C-S-C relations that indicate a sinistral sense of shear. The YSZ is interpreted to form a >30-kmwide zone with discretely partitioned sinistral and dextral shearing. Dextral shearing is constrained at <2662 + 4 Ma, consistent with the deformation history proposed for the Eastern Goldfields Superterrane (e.g. Blewett & Czarnota, 2007, GA Record 2007/14, p. 27-32). No dip-slip movement has been recognised, but strike-slip shearing may have overprinted earlier extensional deformation. The YSZ has a similar geometry to the Laverton Tectonic Zone and Ockerburry shear system, and may share a common structural history. As these crustal-scale zones are interpreted as terrane boundaries (Cassidy et al., 2006, GSWA Record 2006/8) that tap deep fluids, the YSZ may also be geodynamically important with considerable economic significance.
Australian Earth Sciences Convention 2008
Early Mesoproterozoic Crustal Anatexis in the Gawler Craton, South Australia. Justin L. Payne^ Martin Hand, Karin M. Barovich, David E. Kelsey and Peter Kinny^ ^Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, Adelaide SA 5005. ^Department of Applied Geology, Curtin University of Technology, GPO Box 1987, Perth, Australia 6845. The Mesoproterozoic Munjeela Suite, southwestern Gawler Craton, is a group of muscovitebiotite-gamet-bearing peraluminous granites. New U-Pb SHRIMP zircon geochronology demonstrates the intrusions crystallised at -1590-1580 Ma. The -1590-1580 Ma age of crystallisation demonstrates the Munjeela Suite is coeval with the voluminous and economically important Gawler Range Volcanics and Hiltaba Suite graniotoids. However, trace and rare earth element data indicate the Munjeela Suite was not generated as an end-member of fractional crystallisation of the Hiltaba Suite, but rather formed by muscovite-dehydration melting of a meta-sedimentary protolith. One Munjeela intrusion, Pt James, displays relatively unique mineralogical and geochemical characteristics. This intrusion contains rapakivi feldspar textures (interpreted to represent decompression during granite crystallisation) and spessartine-rich xenocrystic garnet. Garnet is demonstrated to be xenocrystic as REE compositions of the gamet demonstrate that, for known REE partitition coefficients between gamet and melt, the gamet could not have grown in equilibrium with the host granitic magma. Nd-isotope data indicates the relatively juvenile (8Nd(T)= -3.2 - +2.5) Munjeela Suite was likely to be generated from melting of a metasedimentary protolith similar to gametmuscovite-biotite-bearing metasedimentary enclaves found within the granite (8Nd(T)= -3.4 - -0.1). U-Pb detrital zircon geochronology indicates maximum depositional ages for the protoliths of these metasedimentary enclaves range from c. 16701625 Ma. The youngest maximum deposition age constrains the timing of metamorphism evidenced by gamet-muscovite-biotite-assemblages to the age range c. 1625-1580 Ma. Calculated mineral equilibria P-T conditions ( up to 7 kbar, 650°C) and petrographic observations provide evidence that metamorphism was associated with crustal thickening. This further highlights the syndeformation, and potentially syn-orogenic, setting for the 'anorogenic' Hiltaba Suite magmatism.
ABSTRACTS alphabetically by surname of presenting author
Evolution of the Gawler-Adelie Craton: Links With Antarctica, Northern Australia and Basement Of The TransHudson Orogen Justin L. Payne^ Martin Hand, Karin M. Barovich and Anthony Reid^ ^ Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, Adelaide SA 5005. Geological Survery, Primary Industries and Resources South Australia, 101 Grenfell St, Adelaide SA 5000. The late Archaean to early Mesoproterozoic evolution of the Gawler-Adelie Craton in Australia and Antarctica is poorly understood. Much of the two terrains are unexposed due to sediment or ice cover. On a global scale, this time period is documented to represent significant cmstal growth by subduction-related magmatic activity and accretionary processes. Although the Gawler-Adelie Craton preserves evidence for at least four orogenic events, there is evidence for only two subductionrelated magmatic events, while orogenic events appear to be dominated by high geothermal gradients. The 2460-2420 Ma Sleafordian Orogeny is correlatable with orogenesis in only three other terrains: the North Australian Craton, Sask Craton of the Trans-Hudson Orogen and the North Korea Peninsula. Evidence based upon event timing, detrital zircon provenance and isotopic data suggests the Sask Craton represents the equivalent of unexposed basement to the Gawler-Adelie Craton. Sleafordian-aged orogenesis occurs shortly after orogenesis in the Napier Complex and Vestfold Hills, Antarctica, and Dharwar and North China Cratons and represents the fmal period of orogenesis before global tectonics underwent a period dominated by extension or tectonic quiescence. The second major tectonothermal event within the Gawler-Adelie Craton is the craton-wide 1730-1690 Ma Kimban Orogeny. The Kimban Orogeny is thought to be a collisional event which is interpreted to correlate with the Strangways and Nimrod Orogenies in the North Australian Craton and Trans-Antarctic Mountains, respectively. Combined with other shared timelines, the Kimban Orogeny provides evidence to suggest the GawlerAdelie Craton and North Australian Craton formed a single landmass for much of the Palaeoproterozoic. Such a model requires re-interpretation of current thinking on the evolution of the Australian continent during the early Proterozoic.
Chemical Composition of Seawater In Neoproterozoic and Paleozoic: A Contribution Based On Study of Fluid Inclusions In Halite From Australia. Tadeusz Marek Peryt , Volodymyr M. Kovalevych^, Wenlong Zang^, Torey Marshall"^ ^ Panstwowy Instytut Geologiczny, Rakowiecka 4, 00975 Warszawa, Poland (tadeusz.peryt@pgi.gov.pl) ^ Institute of Geology and Geochemistry of Combustible Minerals, NASU, Naukova 3A, 79060 Lviv, Ukraine (igggk@mail.Iviv.ua) ^ Division of Minerals and Energy, Department of Primary Industries and Resources, Adelaide, SA 5000, Australia (zang.wen-long@saugov.sa.gov.au) ^ Northern Territory Geological Survey, GPO Box 3000, Darwin, NT 0801, Australia Data on chemical composition of brines in primary inclusions of marine halites and on mineralogy of marine evaporites and carbonates lead to the conclusion that during the Phanerozoic two long-term cycles of chemical composition of seawater existed (V.M. Kovalevich et al., 1998, J. Geology, v. 106, p. 695). During each of those cycles, seawater dominantly a Na-K-Mg-Ca-Cl (Carich) type changed to a Na-K-Mg-Cl-S04 (S04-rich) type. Upper Neoproterozoic halites from Salt Range Formation in Pakistan and Ara Formation of Oman contain fluid inclusions indicating S04-rich brines. In turn, samples of recrystallised halite from the Bitter Springs Formation (840-830 Ma) contain inclusion brines that are entirely Ca-rich, indicating that basin brines and seawater were Ca-rich during deposition of central Australian evaporites, and that during the Proterozoic, significant oscillations of the chemical composition of marine brines, and seawater, occurred, which are similar to those known to exist during the Phanerozoic. Ca-rich seawater dominated for a substantial period of time (more than 200 Ma), at 650 Ma, this was replaced by S04-rich seawater, finally returning to Ca-rich seawater at 530 Ma, as indicated by study of fluid inclusions in halite from the eastern Officer Basin (and other coeval halite basins). Late Ordovician Mallowa Salt in the Canning Basin also contains fluid inclusions of a composition indicating that parent brines (and thus the seawater) were of a Ca-rich type during Late Ordovician. The data points of the Mallowa Salt are located close to the fields of the Early Cambrian and Late Silurian basins. The Late Ordovician seawater was characterized by a K content similar to that of modern seawater whereas its Mg content was about 30% lower, its Ca content was approximately three times higher, and the SO4 content was three times less. For a more quantitative reconstruction of the seawater composition, halite samples from the lowest part of the evaporite formation should be studied.
197
198 ABSTRACTS
atphatsetieallytofsurname of presenting author
Findings from Regolith-landform Studies at Coyote Au-deposit, Western Australia. A n n a E. Petts^ ^ Steven M. Hill^'^ Lisa Worrall^'^ ^ Cooperative Research Centre for Landscape, Environment & Mineral Exploration ^ Department of Geology & Geophysics, School of Earth & Environmental Sciences, University of Adelaide, Adelaide, South Australia 5005. (anna.petts @ adelaide. edu. au) In south-eastern Australia regolith-landform mapping allows mineral explorers to constrain geomorphic processes (which influence physical and chemical dispersion) - regolith-landform mapping is now common practice. Regolith-landform mapping is not as common in greenfields terrains such as the Tanami Desert region. The landscape of the Tanami Desert varies from rolling hills, to vast sandplains and wide palaeochannels. Whilst there has been regional scale regolith-landform mapping (Wilford, 2000; Regolith- landform mapping and GIS synthesis for mineral exploration in the Tanami Region. Canberra, CRCLEME: 146R), within the Tanami Region, there are no publicly available regolith-landform maps at tenement scale. Regolith-landform mapping has been undertaken at a tenement scale. These maps have been used as the framework for research activity in the CRC LEME Tanami Collaborative Regolith Research Project. This project aims to establish effective strategies for exploring through the regolith in the Tanami. Additional postgraduate work by Petts (2008, In Process) has been specifically directed towards testing the effectiveness of using termite mounds (termitaria) as sampling media and also as mappable regolith-landform attributes (Petts, Hill & Worrall, 2007; Abstract No 87, Geological Society of Australia). A regohth-landform map of the Coyote Audeposit (now being mined) was compiled from data collected between February 2005 and January 2006. Using ArcGIS software, datapoints were added as layers over an orthophoto of the deposit. Polygons were constructed from draft polylines based on remote sensing images, which was then verified with field data. Important findings from this mapwork include the transition from distal, sand-dominated colluvial sheetwash fans in the north of the mapping area, to silt-rich colluvial depressions and alluvial plains south of mineralisation, bordering a wide valley dominated by a west-flowing palaeochannel. The surficial expression of mineralisation occurs at the boundary between these two main regolithlandform types, potentially impacting future exploration models for the Tanami Desert as explorers struggle to understand the transportation of anomalous geochemical signatures in the landscape. Australian Earth Sciences Convention 2008
Studying surface attributes to reveal hidden regolith profiles: Geochemistry and mineralogy of termite mounds around the Coyote Au-deposit and surrounds, Western Australia. Anna E. P e t t s ^ Steven M . Hill^' ^ Lisa Worrall^'^ ^ Cooperative Research Centre for Landscape, Environments & Mineral Exploration ^ Department of Geology & Geophysics, School of Earth & Environmental Sciences, University of Adelaide, Adelaide, South Australia 5005. [anna.petts @ adelaide. edu.au) ^ Onshore Energy & Minerals Division, Geoscience Australia, Corner of Jerrabomberra Dr and Hindmarsh Ave, Symonston, Australian Capital Territory 2690. The most daunting aspect for geoscientists conducting research in Australia's north is the lack of bedrock exposure. Prompted by the minerals industry and agencies conducting fieldwork in areas of significant transported cover, innovative new developments in both ground-based and airborne geophysics have allowed for the characterisation of the uppermost layers of the Earth. These new techniques however do not give insight into the mineralogy or chemical composition of these overlying sediments. Sampling ready-made mounds of earth, created over many years by soil organisms has been a well-documented technique in Ancient Times (Herodotus) through to modern day exploration in West Africa. These well-cemented, often giant above-ground nests offer the modern day mineral explorer a type of regolith "x-ray glasses" which 'see through' the upper regolith profile to the weathered bedrock, which may be potentially hosting mineralisation. This study introduces key issues from recent PhD research in the Tanami Desert at the Coyote Au-deposit, now an active gold mine along the Tanami Track in Western Australia. Over two years site data including regolith-landform descriptions and termite mound locations and termitaria samples integral to this geochemical and mineralogical study were collected. Preliminary results showed that termitaria geochemistry, analysed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS), effectively delineated mineralisation along a single transect, justifying the collection of additional samples. These have been analysed by ICP-MS, XRD and XRF. Results from these and the original analyses will be discussed with respect to mineralisation. Analytical results from select field sites will be compared and discussed in relation to geochemical exploration in areas of transported
ABSTRACTS alphabetically by surname of presenting author
cover, such as the study site in the Tanami Desert, offering new technologies to geologists working in this terrain.
The Pilbara Drilling Project: Results and Perspectives
Multiple Sulfur and Carbon Isotopic Chemostratigraphy of the 2.73 Ga Carbonated Tumbiana Formation, New Insights for the Fortescue Excursion.
Pascal Philippot^ Martin Van Kranendonk^
Pl^ilippot^,Christophe. Thomazo^'^ , M. er , J. Farquhar ^ Laboratoire de geochimie des isotopes stables, Institut de Physique du Globe de Paris, France: (thomazo @ ipgp.jussieu.fr) ^ Laboratoire Geobiosphere actuelle et primitive, Institut de Physique du Globe de Paris, France: (philippo @ ipgp.jussieu.fr) ^Department of Geology, University of Maryland, College Park,Maryland, USA: (jfarquha @ essic. umd. edu) In order to bring further insights into the environmental conditions prevailing during the negative Fortescue Excursion attributed to an increase in methanotrophic biomass, we carried out a detailed carbon (^^C, ^^C) and multiple sulfur (^^S, ^^S, ^"^S) isotopic study through the entire pristine core drilled from the 2.7 Ga Tumbiana Formation (Pilbara Drilhng Project). Organic 5 CpDB values vary markedly at meter scale and display a bimodal distribution with two maxima at -43 and -28%o. This isotopic record, together with petrological and other geochimical evidence, cannot be explained by secondary processes including diagenesis or metamorphism and argues for the occurrence of two distinct pools of biomass likely produced by different metabolic pathways, photosynthesis and methanotrophy. S^'^ScDT values of sedimentary pyrite vary from -5.8 to 2.7%c (average -0.5%o). Lithologically independant heterogeneities (at centimeter scale) in isotopic composition (>5%o), sulfur content and S/C ratio are best interpreted by coexisting microbial sulfate reduction and sulfur oxidation metabolisms. Sedimentary pyrite display Mass Independent Fractionnation (MIF-S) with A^^SCDT anomalies ranging between -0.24 and 1.64 %c (average 0.46 %c) and correlating positively with the '^C enrichment of organic matter. This observed negative correlation between A^^SCDT of pyrite and S^^CPDB of organic matter suggests that the sulfur components derived from photochemically-processed volcanic gases and delivered to the Tumbiana sediments were ultimately involved in the metabolic activity of sulfureta. It also contrasts with the prediction that an abiotic hydrocarbon haze derived from methane photochemistry explains the ^^C enrichment of organic matter in the sedimentary record because UV shielding by the haze would turn off the MIF-S production.
^ Institut de Physique du Globe de Paris, CNRS & Universite Denis Diderot, case 89, 4 place Jussieu , 75252 Paris 05, France (philippot@ipgp.jussieu.fr) Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia (martin.vankranendonk@doir.wa.gov.au) To investigate the presence and type of life on early Earth and evaluate potential contamination by modern microbial life, a joint scientific project between the Institut de Physique du Globe de Paris and the Geological Survey of Western Australia drilled three diamond drillholes that intersected the 2.72 Gyr carbonateous Tumbiana Formation (Fortescue Group, Hamersley Basin, one drill hole) and the 3.5 Gyr chert-barite Dresser Formation at North Pole (Warrawoona Group, Pilbara Craton, two drill holes). All diamond drill cores were oriented for paleomagnetic studies. Here we present a summary of the investigations performed so far. These include: C, multiple S and Fe stable isotope systematics, Sm-Nd isotope dating of North Pole hydrothermal and sedimentary rocks, noble gas analysis of inclusion fluids, characterization of carbonaceous material using high resolution spectroscopic techniques, DNA extraction of selected drill core samples in order to evaluate the potential occurrence of a modern deep biosphere. Some important new clues on Earth's early habitats are discussed.
Early Archaean Microorganisms Preferred Elemental Sulfur, Not Sulfate Pascal Philippot\ Mark van Zuilen\ Kevin Lepot\ Christophe Thomazo\ James Farquhar^, Martin Van Kranendonk^ ^ Institut de Physique du Globe de Paris, CNRS & Universite Denis Diderot, case 89, 4 place Jussieu , 75252 Paris 05, France (philippot@ipgp.jussieu.fr) ^ Earth System Science Interdisciplinary Center, Department of Geology, University of Maryland, College Park, MD 20742, USA (jfarquha @ Glue. umd. edu) ^ Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia (martin. vankranendonk@doir. wa. gov. au) It has been known for some time that sulfatereducing organisms preferentially process hght over heavy sulfur isotopes (^^S relative to ^"^S) leading to H2S and sulfide minerals such as pyrite (FeS2) that are depleted in heavy sulfur isotopes (negative S^'^S). continued next page... Australian Earth Sciences Convention 2008
199
200
ABSTRACTS alphabetically by surname of presenting author
Ihe isotopic ditterence between pyrites and contemporaneous sulphate-minerals (e.g. gypsum, CaS04 or barite, BaS04) in sediments can therefore be used to trace microbial sulfate-reduction over time, down to 2,500 Myr ago. In rocks older than ca. 2,500 Myr, a much smaller isotopic difference is generally preserved, which could either indicate that microbial sulfatereduction was absent in the Early Archean or that microbial sulfate-reduction operated under low sea water sulfate concentration. An exception are the strongly negative d^'^S values of microscopic sulfides hosted in barite of the 3,490 milhon year old chertbarite deposit at North Pole (Dresser Formation, Western Australia). On the basis of this finding it has been suggested that the record of microbial sulfate-reduction extends into the Early Archean. We show here that the microscopic sulfides at North Pole have a mass independently-fractionated sulfur isotopic anomaly (A^^S) that differs from that of their host sulfate (barite, Philippot et al., 2007, Science, 317, 1534-1537). These microscopic sulfides cannot have been produced by sulfate reducing microbes, nor by abiologic processes that involve reduction of sulfate. Instead, we interpret the combined negative b^'^S and positive A^^S signature of these microscopic sulfides as evidence for the early existence of organisms that disproportionate elemental sulfur.
Geochronology of regolith-landform evolution in Australia: a brief review Brad Pillans^ ^Research School of Earth Sciences, The Australian National University, Canberra, ACT, 0200 (brad.pillans@anu.edu.au) Austraha is often described as an ancient continent, not only for the antiquity of its rocks but also for its landscapes. For example, PermoCarboniferous glacial landforms, weathering profiles and caves at or near the present landsurface, in diverse parts of the Australian continent, suggest a significant Late Paleozoic inheritance in the modern landscape (Pillans, 2007, J. Quat. Sci., v. 22, p. 439). Survival of ancient landforms and weathering profiles in Austraha is commonly explained as being the result of prolonged tectonic stability, coupled with postulated low rates of weathering and erosion. However, while measured rates of long-term (10^10^ year timescales) weathering and erosion in Australia may indeed be low by world standards, they are not low enough to explain the continuous subaerial survival of pre-Cenozoic landforms and weathering profiles. Even at a low mean erosion rate of say 1 m/Ma, more than 100 m could be lost from surfaces that formed prior to 100 Ma. Burial and exhumation must therefore be significant contributing factors in the preservation of such ancient features in the Australian landscape. Australian Earth Sciences Convention 2008
consistent with the evidence from apatite fissiontrack thermochronology (Kohn et al., 2002, Aust. J. Earth Sci., v. 49, p. 697). In this talk I will briefly review the geochronology of Australian regolith-landform evolution in relation to major boundary conditions of chmate, sea-level, atmospheric composition and tectonics. In doing so, I hope to provide some new insights into the antiquity and evolution of Austrahan landscapes.
Hydrothermal Systems Associated with Meteorite Impacts Franco Pirajno^ ^Geological Survey of Western Australia, 100 Plain Street, East Perth WA 6004, Australia (Franco, pirajno @ doir. wa. gov. au) Hypervelocity impacts by comets and asteroids, if sufficiendy large, cause melting of the target rocks due to the instantaneous conversion of kinetic to thermal energy. This thermal energy spreads through a large volume of rock with postshock temperatures estimated at > 2000°C resulting in severe thermal perturbations around the impact site. Additional heat release may also occur from the central structural uplift, which brings hot crust near to the surface. The combined thermal effects result in a spectrum of phenomena from partial melting to high-temperature metamorphism and hydrothermal fluid flow. The effects of impact-related hydrothermal circulation on target rocks, which can extend well below the crater to depths of several kilometres. It is also likely that impact-related hydrothermal fluids can vent at the surface as hot springs and geysers, forming silica-rich deposits, similar to those observed in geothermal areas of active volcanic environments. The effects of hydrothermal fluid flow would be presumably greatly enhanced if the impact occurs in ocean, where seawater would rush into the heated and fragmented target rocks, as probably was the case for Chicxulub. The flow of hydrothermal fluids overprints the mineral assemblages of the target rocks resulting in secondary mineral assemblages, with processes that principally involve cation and H^ metasomatism resulting in hydrothermal alteration. Hydrothermal circulation systems associated with meteorite impact events have been reported from numerous impact structures including: Ries (Germany), Lockne and Siljan (Sweden), Roter Kamm (Namibia), Manson (USA), Vredefort (South Africa), Kardla (Estonia), Sudbury and Haughton (Canada), Shoemaker and Woodleigh (Australia).
ABSTRACTS alphabetically by surname of presenting author
The Yanshanian Tectono-Thermal Event in China and associated Mineral Systems
Devonian Reef Complexes of The Canning Basin: 50 Years On.
Franco Pirajno^
Phillip E. Playford^
^Geological Survey of Western Australia, 100 Plain Street,East Perth, WA 6004, Australia (franco.pirajno@doir. wa.gov.au)
^Geological Survey of Western Australia (phil.playford@doir.wa.gov.au)
Mesozoic-Cenozoic intraplate tectonism and magmatism affected much of the eastern margin of mainland Asia, extending from Far East Russia, through the Baikal and Mongolia regions, to northeastern and eastern China. These phenomena are broadly linked with a complex series of events, involving subduction, collision, post-collision collapse and rifting. The 210-90 Ma Yanshanian tectono-thermal event is a manifestation of this intraplate geodynamic evolution and is characterised by a range of intrusives from gabbro to granitic rocks, including A-type alkaline rocks and Basin-andRange style rifting with volcano-sedimentary basins (Shanxi Rift System). Volcanic rocks are bimodal in composition but dominated by alkali basalt. Intrusive activity particularly affected regions extending for up to 1000 km westward along major zones of weakness, such as the boundaries between the North and South China Cratons and the North China and Siberian Cratons, and the crustal-scale NNE-trending Tan Lu Fault. A wide range of mineral systems are associated with the Yanshanian magmatism. These include intracontinental Au-Ag lodes, porphyry CuMo, Au-bearing breccia pipes, skarns, Kiruna style magnetite deposits and low-sulphidation epithermal systems. Age data indicate three main periods of magmatic activity and associated mineralisation at approximately 160 Ma, 140-130 Ma and 100-90 Ma. The Yanshanian event may be linked to subduction systems and rifting following collision between Siberia and Mongolia-North China (Jurassic-Cretaceous) and in the western Pacific (Cenozoic). The thermo-tectonic evolution of the lithospheric mande beneath eastern China that led to the Yanshanian event is envisaged to have resulted from lithospheric extension, lower crust and lithospheric keel delamination and asthenospheric upwelling. Comparable geodynamic settings of the same age are present in eastern Australia and western Europe (e. g. Wilson and Downes, 1991, J. Petr. 32: 811-849).
The first detailed study of a Devonian reef complex in the Canning Basin was undertaken at the Oscar Range in 1956, followed by more detailed work at Windjana Gorge in 1958. Those two ground-breaking studies, by geologists of West Australian Petroleum (WAPET), laid the foundation for future research on these rocks. Many of the subsequent studies have been by staff of the Geological Survey of Western Australia and its various collaborators. The magnificently exposed and intensively studied Canning Basin reef complexes now serve as a model for interpreting reefal deposits throughout the world. Fundamental advances made over the past 50 years in interpreting the reef complexes include recognition of: steep depositional dips in marginalslope deposits; facies equivalence of platform, marginal-slope, and basin deposits; the major role of microbes in limestone deposition; fracturing of early-cemented limestones leading to networks of neptunian dykes, platform-margin collapse, and major debris-flows; large microbial bioherms that grew in water more than 100 meters deep; welldefined cement stratigraphy; precise biostratigraphic zonation using conodonts and ammonoids; the role of Devonian tectonism and sea-level change in controlhng development of the reef complexes; the interrelationships between facies of the reef complexes and contemporaneous conglomerates; growth over cool-water seeps of stromatolite mounds with associated barite and iron-sulfide mineralization; and the role of the Permian glaciation in planing-down the reef complexes and forming subglacial karst and Nye channels.
Geochemical Survey in the Highlands of Papua New Guinea Benny Poke . Knut Derkmann ^MSSP-GEOMAP c/o Mineral Authority of Papua New (kderkmann@mra.gov.pg)
Resource Guinea,
The MSSP-GEOMAP project is a 5-year programme of geological mapping, geochemical reconnaissance surveying and enhancement of capabilities of the Geological Survey of Papua New Guinea (PNG). The basic remit of the project is to survey 24 quarter-degree sheets covering and area of approximately 73,600 km^ of the PNG Highlands. The project will carry out new field surveys aimed at understanding the
continued next page..
Austraiian Earth Sciences Convention 2008
201
202 ABSTRACTS aiphabeticaiiy by surname of presenting author
geology and evolution of the PNG Highlands, and providing a comprehensive set of geological maps (at 1:100,000 scale) and metallogenetic maps (at 1:250,000 scale), together with accompanying detailed sheet explanations. The main topics of the geochemical survey are a drainage geochemical survey (sampling density, analytical techniques), a geochemical orientation survey, heavy mineral survey and rock sampling (bedrock & floats) to gather additional geological information. An orientation survey was carried out in 2006 on two known and accessible prospects in the Mount Hagen area, which reflect typical styles of minerahzation likely to be found in the Highlands region were sampled. These were the Mount Ambra - River Komun prospect, which appears to have a porphyry-style Cu-Au-Mo anomaly; and the Kuta prospect which is reported to be an epithermal system with Au and a weak As anomaly as well as sporadic Bi-Te-Ba anomalies. The target of the orientation survey was to find out the grain size fraction, representative for the areas. Therefore 3 different fractions were sieved. The stream sediment samples where dissolved with different digestion techniques (aqua regia & four-acid digestion) and different analytical methods (AAS & ICPMS). 50 elements including Hg were analyzed. For the discussion of the results of the orientation survey the elements Au, As, Sb, Hg, Ba, V, Cu, Mo, Pb, Zn and Ag, characteristic for the epithermal gold and porphyry style mineralization, were selected. The 80 mesh fraction gives a good geochemical response and is the more feasible to collect from high energy rivers. The aqua regia digestion method permits Hg to determine on the same solution as part of an ICP-element package. It produces lower absolute element concentrations than the fouracid method, but gives better anomaly/background contrast for several key elements. Sampling strategy, after the experience of 2 field campaigns, was modified and adopted to the extremely rugged terrain of the Highlands of PNG. Even with helicopter support the areas are in great parts inaccessible because of dense vegetation. Especially the headwaters which are interesting from the geochemical point of view are very difficult to reach. Higher order drainage sampling combined with higher sample quantities were carried out to get a calculated sampling density of 1 sample per 3 km^. Excluded areas were defined on the basis of not significant unprospective areas especially in the karstic ground and some pristine Quaternary volcanic centres like Mount Hagen and Mount Giluwe.
Australian Earth Sciences Convention 2008
Bayesian Network Classifiers for GISbased Mineral Prospectivity Mapping Alok Porwal^ ^ Centre for Exploration Targeting, WA (alok.porwal@gmaiLcom)
UWA,
Crawley,
High performance levels of neuro-fuzzy and neural network models in empirical mineral prospectivity mapping indicate that machine learning algorithms can efficiently recognize and account for possible conditional dependencies amongst input predictor patterns. Considering that the most serious theoretical objection to Bayesian probabilistic models is posed by the violation of the conditional independence assumption, suitable parameter learning algorithms can be used to induce Bayesian models to recognize and account for possible conditional dependencies amongst input predictor patterns. This paper presents a Bayesian network classifier that uses probabilistic machine learning algorithms for dealing with conditional dependencies amongst input predictor patterns. In order to examine the tolerance of Bayesian classifiers for the violation of the conditional independence, three Bayesian classifiers are developed: (a) a naive Bayesian classifier that assumes complete conditional independence of input predictor patterns, (b) an augmented naive Bayesian classifier that uses probabilistic machine learning algorithms to recognize and account for conditional dependencies amongst input predictor patterns and (c) a selective naive classifier that uses only conditionally independent predictor patterns. The training of the classifiers involves determining dependencies amongst predictor patterns and estimating conditional probability of each predictor pattern given the target deposit-type. The output of a trained classifier determines the extent to which an input feature vector belongs to either the mineralized class or the barren class and can be mapped to generate a favorability map. The procedures are demonstrated by an application to base metal prospectivity mapping in the Proterozoic Aravalli Province (western India). The results indicate that (a) although the naive Bayesian classifier performs well and shows significant tolerance for the violation of the conditional independence assumption, the augmented naive Bayesian classifier performs better and exhibits finer generalization capability, and (b) the rejection of conditionally dependent predictor patterns degrades the performance of a naive classifier. The augmented naive Bayesian classifier matches the performance of the neural network and neuro-fuzzy models in base-metal prospectivity mapping of the Aravalli Province. In addition, the Bayesian classifier offers a significant advantage over the neural network and neuro-fuzzy models, namely, it is not a black box
ABSTRACTS 203 alphabetically by syrname of presenting author
and its parameters can be easily interpreted for gaining insights into the data and genetic processes.
Spatial Mathematical Models for Mineral Prospeetivity Mapping
Using Numerical Modelling to Target Undiscovered Gold in a Brown-Fields Environment, an Example from Tarmoola WA
Alok Porwal^
Warren Potma^
^University of Western Australia, Centre For Exploration Targeting, 35 Stirling Highway, Crawley, H^A, 6009
^ CSIRO Minerals Down Under National Research Flagship/prnd'^CRC. PO Box 1130, Bentley, WA, 6102.
A key problem in spatial-mathematicalmodel-based mineral prospeetivity mapping is the selection of appropriate functions that can effectively approximate the complex relationship between target mineral deposits and recognition criteria. This paper describes a series of spatial mathematical models based on different linear and non-linear functions and evaluates them by applying to base-metal prospeetivity mapping of the Aravalli province, western India. Linear models described in this paper are an extended weights-of-evidence model and a hybrid fuzzy weights-of-evidence model, while non-linear models are knowledge and data-driven fuzzy models, a neural network model, a hybrid neurofuzzy model and an augmented naive Bayesian classifier model. The parameters of the knowledgedriven fuzzy model are estimated from the expert knowledge, while those of the neural network and Bayesian classifier model are estimated from the data. The two hybrid models use both expert knowledge and data for parameter estimation. The results indicate that, as compared to the linear models, the non-linear models generally perform better. This is attributed to the ability of non-linear functions to (a) better approximate the relation between mineral deposits and recognition criteria and (b) recognize and account for possible dependencies amongst recognition criteria. Although the linear models do not fit the data as efficiently as the non-linear models, they are easier to implement using basic GIS functionahties and their parameters are more amenable to geoscientific interpretation. In addition, the linear models are less susceptible to the curse of dimensionality as compared to non-linear models, which makes them more suitable for applications to mineral prospeetivity mapping of the areas where there is a paucity of training mineral deposits. The hybrid models that conjunctively use both knowledge and data for parameter estimation generally perform better than purely knowledgedriven or purely data-driven models. This is attributed to the capability of the hybrid models to cross-compensate the deficiencies in either the knowledge-base or in the database.
Numerical modelling of coupled geological processes have been successfully applied to understanding mineralisation processes in many ore systems. At Tarmoola, coupled deformation and fluid flow modelling was used, firstly, to reproduce the observed distribution of gold mineralisation at the camp and lode-scale, and secondly, to identify similar targets under cover The "reverse engineering" or forward modelling phase provided constraints on the key controlling the location of known mineralisation at Tarmoola, such as far-field stress, rheology and permeability contrasts. Constraints derived from this phase were then used as the basis for predictive modelling around the remaining margin of the Tarmoola granodiorite, which is hidden under cover. The shape of the granodiorite was derived from interpretation and modelling of the geophysics (detailed gravity & magnetics inversion & worming), along with precise contact information derived locally from mining and drilling activities. Numerical models highlighted three new high priority drill targets on the margins of the granodiorite away from the known Tarmoola ore body. Tarmoola, like the Granny Smith deposit, is interpreted to have formed as a result of syn-gold strain and fluid-flow partitioning proximal to a large granitic intrusive. Such intmsives are easy to identify from regional geophysical datasets, but provide a prohibitively large drill target if the mineralisation halo is not exposed at surface. This work shows that numerical modelling can predict distinct regions on the margins of such intrusives where dilation and fluid focussing is more likely to occur. Such locations are almost entirely dependant upon intrusion shape, which can be gleaned with sufficient resolution from detailed aeromagnetics and gravity inversions and worming.
Australian Earth Sciences Convention 2008
204 ABSTRACTS alphabetically by surname of presenting author
New Sediment Datasets Help Characterise Seabed Habitats for Australia's Margin: Implications for Marine Environmental Planning Potter, Anna\ Baker, Christina^ Tran, Maggie^ ^Marine & Coastal Environment Group, Petroleum and Marine Division, Geoscience Australia, Canberra, ACT 2601, Australia. The Department of the Environment and Water Resources (DEW) are currently identifying Marine Protected Areas (MPAs) on the AustraUan Margin with the intention of preserving species and habitats that are under pressure from human activities. One challenge facing marine scientists is to provide quantitative spatial information on regional scale biodiversity to support this decision making process. Studies have indicated that some physical variables, including geological properties such as seafloor sediment texture and composition that can be mapped at regional scales, may have significant influence on the distribution of benthic biota. Since 2003, the Seabed Mapping and Characterisation project at Geoscience Australia has been producing seabed sedimentology information to support marine environmental planning. Although sediment properties have the potential to be mapped efficiendy at regional scales, a relative paucity of quantitative data for certain regions of Australia's marine jurisdiction, especially the deep-sea, has previously limited the application of this information in marine planning. Between 2005 and 2008, Geoscience Australia in collaboration with DEW have completed the first synthesis of the regional seabed sediment properties for Australia's Southwest, Northwest and Eastern Margins. Results were based on around 1,700 existing and >2,000 new quantitative sediment data points generated for the project. This work has added significandy to previous knowledge and confirmed the need for these data, not only for environmental management but for other regional-scale applications, including regional geological studies and margin evoludon studies. A consistent data set for the region makes it possible for the first dme to quantify the distribution and extent of specific seabed sedimentary environments within the study areas for example gravel-dominated marginal terraces, and regions of abyssal plain dominated by non-carbonate mud. Geoscience Australia aims to continue to increase the coverage, resolution and accuracy of sediment distribudon maps for Australia's marine region.
Australian Earth Sciences Convention 2008
Tertiary Geoscience Education in Australia: What future? Trevor Powell^ ^Australian Geoscience Council, c/o 15 Jaeger Circuit, Bruce ACT 2617 {tpowell@actewaglnet.au) University geoscience condnues to lose status and visibility through merger of departments and reduction in staffing levels. This reflects the unfavourable economics of maintaining teaching capacity in minority disciplines, such as geoscience, under current funding arrangements. Many of the 'geoscience departments' in the 16 universities having the capacity to teach a geoscience major, are uneconomic based on teaching the current number of students. They are dependent upon for their survival upon internal cross subsidy. Differentiation in degree types has emerged where some universides have created 'geoscience degree' from a blend of physical geography or environmental courses and traditional 'solid earth science' courses whilst others have maintained a disdnction between degree types. This change in teaching profile is reflected in areas where thesis topics can be supervised. Nationally, student enrolments have increased 18% over the last 5 years, but all have occurred in levels 1 -3 with enrolments in Honours declining a further 6% over the 50% that occurred in the previous decade. Retention of students into honours and higher degree courses is a major problem and further threat to the economic viability of many departments. At the Austrahan Geoscience Council's 2007 Summit on Tertiary Geoscience Education, there was a consensus that without acdon it was unlikely the current situation would improve and there was a significant chance of further deterioration. It was recognised that a range of initiatives would be required and that no single measure or agency acdon is likely to impact the current situation. It was also recognised that a national framework was required for these initiatives and within which individual institutions could pursue their own interests. Some characteristics of a national system were identified and processes put in place to develop the national framework. The current state of development of this national framework and actions will be discussed.
Three Dimensional Modelling of Natural Hazards Using Geographic Information Systems Dr. D. John Prabaharan^
^ Department of Planning and Infrastructure, Perth Western Australia - 6000 (jdp27@yahoo.com) Three dimensional visualisation models have a variety of applications in natural hazards and disaster management studies. Geographic Information System (GIS) provide a new approach to show the natural hazard details in 3D model, and offers a domain to deliver the processed data
ABSTRACTS aiphabatfcally by surname of presenting author
efficiently. The construction of visualisation model can facilitate the interpretation of natural hazard details in 3D and is crucial for the purpose of disaster management. In this study, GIS unique functionality of 3D modeling capability is utilised to model the earthquake details of Western Australia. The importance of development of 3D model is discussed in the context of disaster management.
Tsunami Hazard in South-Eastern Australia: Preliminary Findings From Palaeotsunami Investigations On The NSW Coast. Amy Prendergast^ ^Geoscience Australia, Canberra (amy.prendergast@ga.gov. au)
Palaeotsunami investigations can enhance our understanding of tsunami hazard in the Australian region, providing a means of assessing future risk. Previous researchers have suggested that at least six large tsunami impacted the NSW coast during the Holocene, some with run-up in excess of +100 m asl and inundation of 10 km inland. However, this evidence is contentious as it focuses on poorly understood rocky shoreline features and proposes tsunami signatures that have not been described in other parts of the world. If such evidence is substantiated, it has profound implications for the tsunami preparedness of the NSW communities. This study focuses on late Holocene coastal sedimentary records from backshore environments in NSW to develop an assessment of whether catastrophic marine inundation such as tsunami played a significant role in coastal evolution. The advantages of studying backshore environments are that a more continuous sedimentary record is likely to be preserved than on rocky shorelines and an estimate of tsunami recurrence can be obtained if several tsunamigenic units are found in sequence. Fifty cores from sixteen coastal water bodies in southem and central NSW were studied for evidence of past tsunami inundation. Potentially tsunamigenic sediment horizons were identified in some water bodies, which may be a resuk of localised submarine slump-induced palaeotsunami. However the small size and discontinuous distribution of these sedimentary units does not support the theory of 'mega-tsunami' inundation. If such 'mega-tsunami' had occurred, definitive evidence for them should be preserved on a wider scale in the backshore sedimentary record. This suggests that previous research for mega-tsunami on the NSW coastline needs to be re-evaluated.
Formation of the Inner Solar System: new insights revealed by spacecraft data. Andrew Prentice ^ School of Mathematical Sciences, University, Clayton, Victoria 3800, (Andrew.prentice@sci. monash. edu. au)
Monash Australia
The first flyby of Mercury in January 2008 by the NASA MESSENGER spacecraft, the arrival at Venus of the ESA Venus Express in April 2006 and the steady stream of data from the Mars fleet of rovers and orbiters has aroused fresh interest in understanding the origin of the terrestrial planets. The avalanche of new data from these probes will give a basis for finding the exact thermo chemical and thermophysical conditions which existed at the time these bodies condensed from the solar nebula. Each planet has its own distinct chemical signature and story to tell. Mercury is extremely dense for its size. Fe-Ni makes up 67% of its mass. Venus is very dry relative to the Earth while Mars may hold more water per unit mass than the Earth, as well as twice as much S. A strong case can thus be made that (i) each body formed from materials close to its current location and (ii) that there was no widespread orbital mixing of condensate material during accretion (M. Drake & K. Righter, 2002, Nature, v. 416, p. 39). This situation finds a ready explanation within the Modem Laplacian theory of Solar system origin (hereafter MET) (A. Prentice, 2001, Earth, Moon & Planets, v. 87, p. 11; ibid, 2006, PASA, v. 23, p.l). According to the MLT, the planetary system condensed from a concentric family of orbiting gas rings. These rings are shed by the contracting protosolar cloud as a means for shedding excess spin angular momentum during gravitational contraction. It is proposed that very strong supersonic turbulent convection is the mechanism that causes gas ring shedding. (A. Prentice & C. Dyt, 2003, MNRAS, v. 341, p. 644). The temperature and mean orbit pressure of each gas ring (n = 0,1,2,..) vary with mean orbital distance Rn according as T„ - \/ R^'^ and pn - 1/ rI'^ . Mercury formed at 1628 K and consists mostly of Fe-Ni-Cr alloy (mass fraction: 0.671) and gehlenite (0.190). For Venus (910 K), the condensate contains metal (0.313) and Mg0-Si02 (0.589). (Fe-Ni)S (0.107) and tremolite (0.094) first appear at Earth's orbit (673 K). At Mars (454 K), Fe condenses as fayalite (0.192) and FeS (0.196). H2O ice first condenses at Jupiter's orbit (158 K). Titan formed in a solar orbit, prior to capture by Saturn. In this lecture, the most recent spacecraft data for the inner planets are discussed alongside the various theories of planetary origin which have been put forward to explain the data.
Australian Earth Sciences Convention 2008
205
206
ABSTRACTS aiphabeticaily by surname of presenting author
Understanding Natural Hazards Using Field Geology and Geochronology Mark Quigley^ ^ School of Earth Sciences, The University Melbourne (mquigley@unimelb.edu.au)
of
Terrestrial landscapes and sediments record the impacts of infrequent but potentially catastrophic natural hazards, including large earthquakes, landslides, super-floods and climate change. Integrated geologic-geochronologic studies of fault scarps, alluvial sequences, speleothems, and continental landscapes are crucial in order to better understand these natural hazards, many of which operate on time-scales longer than historical records. I will discuss how the use of field geology has been integrated with emerging analytical methodologies such as cosmogenic nuclide dating, optically stimulated luminescence, and U-Th dating to quantitatively investigate natural hazards in southcentral Australia. From such investigations, many interesting hypotheses regarding the relationships between tectonics, climate change, catastrophic weather and landscape evolution have emerged (e.g., Quigley et al., 2007, Basin Research, v. 19, p. 491505; Quigley et al., 2007, EPSL, v. 261, p. 120-133; Quigley et al., 2007, ESPL, v. 32, p. 929-944; Quigley et al., 2006, AJES, v. 53 , p. 281-301).
A Kinematic, Metamorphic and Geochronological Framework For Intracratonic Reworking In The Western Musgrave Block, Central Australia: Evidence For Lower Crustal Extrusion? Raimondo, T.^ Collins, Hand, M.\ Walker-Hallam, A.^ Smithies, H.^ Evins, P.^ ^ Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, Adelaide SA 5005 (thomas. raimondo @ student, adelaide. edu. au; alan. collins @ adelaide. edu. au; martin, hand @ adelaide. edu. au) ^ Heathgate Resources, 45 Grenfell St, Adelaide SA 5000 (althea. walker@heathgateresources. com. au) ^ Geological Survey of Western Australia, Mineral House, 100 Plain St, East Perth WA 6004 {hugh. smithies @ doir. wa. gov.au; paul. evins @ doir. wa. gov. au) The crustal architecture of central Australia has been profoundly affected by periods of intracontinental deformation. Within the western Musgrave Block, Western Australia, the Neoproterozoic to Early Cambrian (600-520 Ma) Petermann Orogeny resulted in pervasive mylonitic Australian Earth Sciences Convention 2008
reworking of Mesoproterozoic granites and granitic gneisses at deep crustal levels (P = 10-13 kbar and T = 700-780°C). SHRIMP and LA-ICPMS analysis of zircon and titanite indicate that peak metamorphic conditions were attained at c. 570 Ma, followed by progressive cooling to c. 600-660°C by c. 540 Ma driven by exhumation along the Woodroffe Thrust. A slight increase in average geothermal gradients moving south of this location suggests that deeper crustal sections experienced more rapid exhumation. This is supported by good correspondence between the record of thermal equilibration retained by equilibrium mineral assemblages and the crystallisation conditions of zircon and titanite identified using Ti and Zr thermometry. Shearing conditions during deep crustal mylonitisation appear to be dominantly anhydrous, although evidence of fluid influx into discrete shear zones is indicated by solid-state zircon recrystallisation and relatively hydrous mineral assemblages. This suggests a complex pattern of fluid partitioning and limited structural connectivity between mylonitised domains. At the outcrop scale, the correlation between distinctive structural expressions and strain intensity is interpreted to represent the simultaneous development of pure and simple shearing, resulting in the progressive partitioning of coaxial and noncoaxial strain components into discrete rock packages. This has implications for the genetic interpretation of lineations that plunge at oblique angles to the predominant regional orientation. At the orogenic scale, the relationship between kinematic partitioning and an anomalous lobate geometry of the Woodroffe Thrust trace suggests that north-directed emplacement of a broad thrust sheet was accompanied by southwest-directed lateral extrusion driven by gravitational collapse. This is indicated by the rotation of regional lineation patterns from orogen-parallel adjacent to the approximately linear fault trace to highly oblique at the point of greatest curvature further west, representing a change in the trajectory of material flow caused by lateral escape towards the orogen margin. Pervasive extensional deformation was thus produced in the hanging wall of the Woodroffe Thrust whose kinematic polarity is decoupled from the bulk tectonic transport of the Petermann Nappe Complex.
Moving From 2D to 3D Geological Maps Of New Zealand. Mark S. Rattenburv\ Robert Pamer^ ^GNS Science, PO Box 30-368, Lower Hutt, New Zealand (m. rattenbury @gns. cri. nz) In 2010 New Zealand will have a completely revised second edition series of printed geological maps at a publication scale of 1:250,000. These maps have been funded through the QMAP
ABSTRACTS alphabetically by surname of presenting author
programme and have been designed and constructed through Geographic Information Systems (GIS) software. The underlying GIS geological map database is attribute-rich and will become "seamless" with a nationally consistent and unified stratigraphic lexicon and will be downloadable from the web by 2010. There are many limitations inherent in any conventional 2D geological map, for example, only near-surface geological units with a scale-dependent minimum thickness are portrayed, litde information can be conveyed about underlying geological units, and the detail the map can show is limited by the publication scale. These limitations are being addressed through the design and prototyping of a systematic 3D geological mapping campaign intended for economically significant areas of New Zealand. Input data of variable density but generally sparse and surface-biased have a large influence on the quality and method of 3D map construction. Other geological issues of scale, scope, reproducibility, uncertainty and data input diversity, and software issues of model construction, versioning, updating, compatibility and visualisation have been identified. Compared to 2D GIS software, 3D geological mapping software is evolving rapidly and a spectrum of products, each with their own niche capabilities, are currently available. Methodological differences between the software packages and inherent complexities in constructing geologically plausible 3D volumes mean that there is no "one-stop" solution for geological survey needs. For GNS Science, a key requirement of 3D mapping software is some compatibility/connectivity with 2D GIS where there has been considerable investment in data and expertise.
WOMBAT: An evolving seismic array experiment in Australia N. Rawlinson. B. L. N. Kennett, H. Tkalcic Research School of Earth Sciences, Australian National University, Canberra ACT 0200 Over the last decade, a rolling array of seismometers (known as WOMBAT - SE) has been sequentially deployed throughout southeast Australia to record passive seismic activity. To date, nearly 400 separate sites have been occupied with nominal station spacings of 40-50 km on the mainland and 15-20 km in Tasmania. Deployment periods for each of the 10 arrays installed so far have varied between 4-10 months, and the number of simultaneously recording instruments has ranged between 20-80. The majority of sites have been equipped with vertical component short period instruments, but a recent upgrade of the seismometer pool means that the last three arrays use 3component sensors only. A long term goal of the
experiment is to continue deploying stations throughout eastern Australia in order to achieve high density coverage of the Palaeozoic Orogens that underpin the Tasmanides. The shear volume and diversity of passive seismic data recorded in southeast Australia by WOMBAT - SE makes it a valuable resource for many classes of study, including teleseismic tomography, ambient noise tomography, shallow receiver funcdons (using the three-component data), and array seismology (e.g. illumination of the coremande boundary). One current line of research aims to combine teleseismic data from all arrays in a single inversion for a unified image of the 3-D structure beneath southeast Australia. In this talk, recent results from tomographic imaging of the crust and mande beneath the Tasmanides will be presented, with particular focus on the deep structure beneath the Lachlan Orogen. 3D wavespeed images of this region provide evidence for the presence of a substandal piece of Proterozoic lithosphere incorporated within the subductionaccredon terrane, which has important implicadons for the tectonic evoludon of southeast Australia. WOMBAT
Deformation, Chemistry and Hydrogen in Olivine: Consequences for Mantle Flow Characterisation and Seismic Anisotropy of the Lithosphere. Steve Reddv\ Erin Gray\ Chris Clark\ Kate Wright^, Katy Evans\ Bill van Bronswijk^, Dave Healy\ Brent Mclnnes^ Jon Kirby"^ ^ The Institute for Geo science Research, Dept of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia. (S.Reddy@curtin.edu.au). ^ Nanochemistry Research Institute, Dept of Applied Chemistry, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia. ^ CSIRO Exploration and Mining, 26 Dick Perry Avenue, Kensington WA 6151, Australia The Institute for Geoscience Research, Dept of Spatial Sciences, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia The Theological properties of the Earth's upper mantle are controlled by the most volumetrically important mineral, olivine ((MgFe)2Si04), and thus the physical properties of olivine have significant implications for models of mantle evolution and dynamics. In the Earth's upper mande, dislocadoncontrolled flow associated with large-scale convection leads to strain-induced crystallographic preferred orientations (CPOs) that reflects the operation of a range of different slip systems in olivine. These CPOs control large-scale seismic anisotropy which in turn allows mantle flow directions to be inferred. However, the presence of water in olivine is correlated with different types of
continued next page..
Australian Earth Sciences Convention 2008
207
208 ABSTRACTS atphabetlcaily by surname of presenting author
CPO fabric types such that the interpretation of seismic anisotropy data is not unique. The presence of hydrogen (in the form of water) in the oHvine lattice is considered by many to reflect defect concentrations associated with trace element compositional variations in olivine. Consequently, there are important relationships among olivine deformation, chemistry and hydrogen that are currently unclear. Here we shed light on these relationships by integrating quantitative microstmctural and microchemical analyses from mantle xenoliths from the Pacific island of Lihir. Integration of results from electron backscatter diffraction, electron microprobe and synchrotron infrared spectroscopic analyses of deformed Lihir olivine indicates new constraints on the relationships among mantle olivine deformation, chemistry and hydrogen content that have fundamental implications for our understanding of mantle geodynamics.
dislocations associated with a <001> {100} slip system. Analysis of minor boundaries in area A indicates deformation by either 0 1 0 (001) edge, or [100](100) screw dislocations. In other parts of the grain, [oTo cross slip on (111), ( i l l ) and (112) planes seems likely. These data provide the first detailed microstmctural analysis of naturally deformed zircon and indicate crystal-plastic deformation by the formation and migration of dislocations into low-angle boundaries. Minimum estimates of dislocation density in the low-angle boundaries are of the order of -3.10^^ cm"^. This value is sufficiently high to have a marked effect on the geochemical behaviour of zircon, via enhanced bulk diffusion and increased dissolution rates. Therefore, crystal plasticity in zircon may have significant implications for the interpretation of radiometric ages, isotopic discordance and trace element mobility during high-grade metamorphism and melting of the cmst.
Quantitative Characterization of Plastic Deformation in Zircon.
Multi-scale Earth System Dynamics: Coupling Chemistry and Mechanics
Steven M. Reddy^ Nicholas E. Timms\ Wolgang Pantleon^, Patrick Trimby^
Klaus Regenauer-Lieb^'^, Thomas Poulet^'^ , Delphine Siret\ Florian Fusseis^ , Jie Liu\ Klaus Gessner^'^, Oliver Gaede^, Gabriele Morra^ Bruce Hobbs\ Alison Ord\ Hans Muhlhaus^'"^ , Dave Yuen^ Roberto Weinberg^ and Gideon Rosenbaum^
^ The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia. (s. reddy@curtin. edu. au; n. timms@curtin. edu. au) ^ Materials Research Department, Riso National Laboratory, Frederiksborgvej 399, 4000 Roskilde, Denmark (e-mail address) ^HKL Technology A/S, Majsmarken 1, 9500 Hobro, Denmark, ^ow at: LINK Nordiska AB, LINK Analytical AB, Lejonvdgen 28, 181 22 Lidingo, Sweden. (Patrick. trimby@linknordiska.se) The deformation-related microstructure of an Indian Ocean zircon hosted in a gabbro deformed at amphibolite-grade has been quantified by electron backscatter diffraction. Orientation mapping reveals progressive variations in intragrain crystallographic orientations that accommodate 20° of misorientation in the zircon crystal. These variations are manifest by discrete low-angle (<4'') boundaries that separate domains recording no resolvable orientation variation. The progressive nature of orientation change is documented by crystallographic pole figures which show systematic small circle distributions, and disorientation axes associated with 0.5-4° disorientation angles, which lie parallel to rational low index crystallographic axes. In the most distorted part of the grain, this is the [100] crystal direction. A quaternion analysis of orientation correlations confirms the [100] rotation axis inferred by stereographic inspection, and reveals subtle orientation variations related to the local boundary structure. Microstmctural characteristics and orientation data are consistent with the low-angle boundaries having a tih boundary geometry with dislocation line [100]. This tilt boundary is most likely to have formed by accumulation of edge Australian Earth Sciences Convention 2008
^CSIRO Exploration and Mining, PO Box 1130, Bentley, WA 6102, Australia (klaus.regenauer-lieb@csiro.au) ^Earth & Geographical Sciences, University of Western Australia, WA 6009, Australia ^ETH Zurich, Institute of Geophysics, 8093, Honggerberg, Switzerland ^ESSCC, The University of Queensland, St Lucia, QLD 4072, Australia ^ Department of Geology and Geophysics and Supercomputer Institute, University of Minnesota Minneapolis, Minnesota 55455, United States ^School of Geosciences, Monash University, Clayton, Victoria 3800, Australia ^School of Physical Sciences, University of Queensland, Brisbane, Queensland 4072, Australia Recent advances in computational geodynamics are applied to explore the link between Earth's heat, its chemistry and its mechanical behavior. Computational thermal-mechanical solutions are now allowing us to understand Earth patterns by solving the basic physics of heat transfer. This approach works well at global scale where the basic convection pattern of terrestrial planets can be solved. Applying the same methodology to smaller scales delivers promising similarities between observed and predicted structures which are often the site of mineral deposits. The new approach involves a fully coupled solution to the energy, momentum and continuity equations of the system at all scales, allowing the prediction of fractures, shear
ABSTRACTS alphabetically by surname of presenting author
zones and other typical geological patterns out of a randomly perturbed initial state. The results of this approach are linking a global geodynamic mechanical framework over regional-scale mineral deposits down to the underlying micro-scale processes. Ongoing work includes the challenge of incorporating chemistry into the formulation. For this, we use computational experiments on micro-scale processes and build a Preliminary Reference Earth Material Database PreMDB. Gibbs energy minimization techniques are used to solve equilibrium compositions in chemistry and to predict the basic mechanical properties from chemistry. Physical properties that cannot be extracted directly from the thermodynamic potential functions are complemented by empirical data. The next level of models concerns itself with a homogenization of the mechanical properties to larger scale reproducing micro-chemical and microstructural observations. The predictive power of these models is currently tested based on field data from mineral deposits at micro-decameter scale. The next steps will be to upscale the approach to meter and km scale for mine scale mineral and metal gradients. The global scale modelling will provide better forward simulations for the genesis of giant ore/mineral deposits and other processes of global interest.
From the Strengthening, Emergence and Erosion of Continents in the Neoarchaean, to the Coupling Of Earth's Geochemical Reservoirs. Patrice Rev', Nicolas Coltice^ ^Earthbyte Research Group, School of Geosciences, The University of Sydney, Sydney NSW 2006, (prey@geosci. usyd. edu. au) Laboratoire des sciences de la Terre, Ecole Normale Superieure de Lyon, et Universite de Lyonl, France (coltice@univ-lyonl.fr) Using a thin sheet model of continental lithosphere under a triaxial state of stress, we explore the secular evolution of the height of isostatically balanced collisional mountain belt in the context of ongoing convergence. Our numerical experiments show that until the late Archaean, ongoing collisional convergence was unable to produce topography >2500 m as the continental lithosphere was too weak to support large gradients in gravitational potential energy. During the Neorchaean, the continental lithosphere evolved through a rheological treshold allowing for the development of significant topography. We relate this evolution to the cooling of the upper lithospheric mantle to a temperature at which its rheology contributes significantly to the overall strength of the continental lithosphere. The consequence of the strengthening of the continental lithosphere is fundamental for the
coupling between exogenic and the endogenic envelops. As it happens, the Neoarchaean is a long period (300 Ma) of global changes during which exogenic and endogenic envelops recorded major shifts in composition towards modern values. This transition from primitive to modern Earth has often been presented in the context of a major pulse of crustal growth and differentiation, super-plume activity and/or orogenic crisis. Here we propose that during the Neoarchaean the exogenic envelops, that were until then coupled to the mantle through hydrothermal vent, volcanism and oceanic floor alteration, also became coupled to the continental crust through relief-generating tectonics processes and erosion, hence changing the balance between mantle versus crustal interaction with the exogenic Earth.
On The Dynamics of Active Continental Margins Patrice Rey^ and Dietmar Miiller^
^Earthbyte Research Group, School of Geosciences, The University of Sydney, Sydney NSW 2006, (prey@geosci. usyd. edu. au, dietmar@geosci. usyd. edu. au) Slab rollback is a favourite amongst the processes leading to the fragmentation of active continental margin and the opening of marginal basins. On the basis of 2D thermo-mechanical numerical experiments we argue that gravitational forces acting on cordilleran orogens and magmatic arcs can drive a range of tectonic processes including extensional gravitational collapse and fragmentation of the continental margin, the formation of marginal basins, slab rollback and the dispersion of microplates. In this model, slab rollback is a consequence of extension rather than its cause and exhumation of the deep crustal root is a response of centripetal flow underneath marginal seas while contractional deformation is still active at the contact between the ocean and the continent. We apply this model to the Mid CretaceousPaleocene evolution of the Pacific margin of Gondwana, a ca-5000 km long active continental margin built along the edge of the AustraliaAntarctica craton in response to the convergence between Gondwana and the Pacific plate. We propose that during the Mid Cretaceous (120 to 95 Ma) this active margin collapsed in response to a counterclockwise change in the absolute motion of the Phoenix Plate, which had been - until then subducting under the eastern Gondwanaland margin. This change imposed along the margin a new tectonic regime mostly characterized by strike-slip. We envision that this change in plate motion reduced the traction that until then promoted and sustained crustal thickening along the east margin of Gondwana. From Mid to Late Cretaceous, the buoyant rise of the mantle-wedge led to the continued next page... Australian Earth Sciences Convention 2008
209
210 ABSTRACTS alphabeticaily by surname of presenting author
formation of marginal basins such as the Tasman Sea and the Ross Sea (between East and West Antarctica), while forcing slab rollback and the dispersal of continental blocks amongst them: Dampier Ridge, Lord Howe Rise, Challenger Plateau, New Zealand, Campbell Plateau and Mary Bird Land.
Sediment Quality as a Factor of the Distribution of Damage at Bam, Iran Earthquake Khalil Rezaei^ ^Lmu University Germany, Arcis Str.17 Z.3 80333, Munich, Bavaria, Germany, 8033 The physical and mechanical properties of the soil and sediment formations were related to the damages observed in Bam area, in Southeast of Iran, after the earthquake of 26th December 2003(Ms=6.6). Properties such as grain size distribution, sorting, plasticity, electrical resistivity, shear strength, compression index, permeability and P and S wave velocities were measured in order to classify the suitability of the soil and sediments formations, for urban planning, and correlate their mechanical behavior with the damage observed in the construction. According to our observations, a great number of recent buildings were damaged also in points of city far away the faulted zones, where silty and clayey soils dominate, presenting very low permeability, low wave velocity together with high plasticity and compressibility.
Strength of High-Geotherm Lithosphere: Weak, Strong, or Failing? 1
12
Shane Richardson , Klaus Gessner ' , Klaus Regenauer-Lieb^'^ ^Centre for Exploration Targeting, The University of Western Australia, Crawley WA 6009 ^Computational Geoscience, CSIRO Exploration and Mining, Bentley, WA 6102 ^School of Earth and Geographical Sciences, The University of Western Australia, Crawley WA 6009 Estimates of heat production in Precambrian continental lithosphere imply higher temperatures in the crust and upper mantle. We explore the nature of extensional deformation in high temperature lithosphere by solving the fully coupled continuum, momentum and energy equations. The radiogenic element distribution is approximated by a simple exponential parameterisation, and we use a temperature dependent flow law to describe the rheology at depth. Our results show that deformation in the upper crust is extremely thin skinned, with shear
Australian Earth Sciences Convention 200^
zones forming only within the upper 5-10 km of the crust. Due to the high geothermal gradient the lower crust deforms via distributed sub-horizontal flow. The rheological contrast between the lower crust and the upper mantle, which is a defining feature of Phanerozoic lithosphere, is significantly reduced by the higher geothermal gradient. The overall weak lower crust and upper mande result in significantly different deformation behaviour compared to Phanerozoic lithosphere. Lithospheric scale failure, which is a requirement for the formation of rifted passive margins, is unlikely in high geotherm lithosphere.
Neoarchean Siliciclastic Sedimentary Successions of the Central Yilgarn: An Equivalent to the Eastern Goldfields Superterrane Late-Stage Basins? Riganti. M o r r i s , P.A.^
Chen,
S. ¥ . \
Wyche,
^ Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia (angela. riganti@doir. wa.gov. au) Neoarchean siliciclastic successions in the central and northern Southern Cross Domain of the Youanmi Terrane (central Yilgarn Craton) share many similarities with the late-stage basins of the adjacent Eastem Goldfields Superterrane (EGS) and many other Archean provinces worldwide. They are preserved as scattered, linear or synclinal remnants of sedimentary depocentres that evolved late in the tectonic history of the terrane. Like the EGS latestage basins, the central Yilgarn successions typically post-date an earlier regional folding event in the underlying greenstones, and are themselves strongly deformed by later tectonic events. Although not as well endowed as their EGS equivalents, central Yilgam late-stage successions do host structurally controlled gold mineralization. Whilst there are notable similarities, the central Yilgam and EGS late-stage basins also show important differences. Most significantly, basins in the Central Yilgam are temporally associated with calc-alkaline volcanic centres, and there appears to be a substantial hiatus between the probable age of the regional greenstone succession and the clastic central Yilgam late-stage sediments compared to those in the EGS. The sediments of the central Yilgam basins are dominantly fluvial deposits, whereas those of the EGS late-stage basins record transitions from fluvial to deep-marine facies and from distal to proximal deep-marine environments. Recently acquired geochemical data for the Diemals Formation in the central Yilgam are consistent with a local, predominantly easterly, detrital source, as opposed to a south-propagating uplift for the EGS. The similarities and differences related above need to be assessed in the broader context of the Yilgam Craton evolution. The association between some of the central Yilgam late-stage basins and felsic volcanic rocks that are slightly older than possible arc-related volcanic rocks in the EGS
ABSTRACTS 211 alphabetically by surname of presenting author
suggests that they may have formed during the early stages of the arc-continent colhsion that accreted the EGS to the Yilgam proto-craton.
Hyperspectral Modelling in Mining & Exploration: Advances in the Understanding of StructurallyControlled Mineralisation Tony Roache^ ^ prnd'^CRC, School of Earth Sciences, University of Melbourne, Victoria, Australia, (tony, roache @ csiro.au)
The 3010
Hyperspectral modelling incorporates threedimensional querying and plotting of large drill hole-derived Short Wave InfraRed (SWIR) spectra datasets in order to spatially characterize mineralogical distribution. At the St Ives gold mine, Western Australia, two examples of hyperspectral models identified that it is possible to identify the distribution of structurally-focussed hydrothermal fluids, and thus create comprehensive 3D maps that resolve the genesis of structurally controlled deposits. Gradients in the abundance and composition of alteration defined planar surfaces that represented spatially continuous geological structures. The existence and orientation of hyperspectrallyinterpreted structures were validated through the geological logging of oriented diamond drill core. Within the Greater Revenge Area (GRA), three previously unidentified shallow-dipping foliation planes - W H l , WH2 and WHS - were modelled from hornblende, Fe-biotite and Fechlorite hyperspectral indices. W H l - 3 are defined by Fe-biotite and contain gold mineralisation if they intersect with rheologically-controlled, hyperspectrally-derived haematite, epidote, gypsum, muscovite and chlorite-rich domains. Distal to mineralisation, W H l - 3 contain hornblende and an overprint of the latter, Fe-chlorite. Areas of greatest gold mineralisation are coincident with the intersection of shallowly-dipping W H l - 3 structures. Hyperspectral modelling validated the structural controls on mineralisation at the Bellerophon gold deposit. Steeply NE-dipping mineralogical gradients are defined by the separation of muscovite and phengite+chlorite+epidote. Moderately WSW-dipping paragonite gradients represent surfaces that separate high paragonite abundance from little or no paragonite. The steeply NE-dipping and moderately WSW-dipping mineralogical gradients represent the main penetrative foliation and a relatively late crenulation cleavage, respectively. Most of the gold mineralisation at Bellerophon is contained between the two muscovite-phengite-f-chlorite+epidote and paragonite gradients, and the intersection of the two is parallel to the moderately northerly plunge of gold mineralisation.
Mineral Exploration-related research in the Minerals Down Under National Research Flagship Paul Roberts, David Gray^ ^CSIRO Exploration and Mining, PO Box 1130, Bentley WA 6102, Australia (paul. a. roberts @ csiro. au) The Minerals Down Under National Research Flagship ("MDU") is part of the CSIRO-led Australian National Research Flagship program which commenced in 2002. These Flagships involve important collaborative links with most Australian research institutions and are aimed at solving problems of national importance. MDU received funding in the May 2007 Commonwealth Budget and commenced full operations in October of that year. MDU's major goal is to assist the Austrahan minerals industry to exploit new resources with an in-situ value of $ 1 trillion by the year 2030. The research program designed to address this goal consists of four research Themes: (1) Discovering Austraha's Mineral Resources ("the Discovery Theme"), (2) Transforming the Future Mine, (3) Securing Australia's Future Ore Reserves and (4) Driving Sustainable Processing through System Innovation. The Discovery Theme aims to assist the Australian mineral exploration sector discover $250 billion of new mineral resources by 2030. Its research program is aimed at developing techniques and technologies of particular importance to Austrahan explorers. With an annual budget greater than $20 million and staffing in CSIRO alone of approximately 80 researchers, it is well placed to do so. This core effort is being expanded through close collaborative relationships with Geoscience Australia, State Geological Surveys and a number of Australian universities and delivery to the Australian mineral exploration sector. The most important exploration challenge in Australia today is the need to discover new high value ore deposits at greater depths and/or under post-mineral cover for a lower cost than is possible today. To do so, explorers must be able to achieve the following far more efficiently and effectively than is now possible: (1) map all minerals at surface and down drill holes, (2) develop new low cost geophysical technologies for mapping the Australian continent, (3) integrate all data together (geology, geophysics and geochemistry) to interpret 3D geology at all scales, (4) develop predictive tools based on a quantitative understanding of geochemical behaviours in post-mineral cover, (5) predict the observable characteristics and/or location of new mineral deposits at depth, and (6) drill exploration targets more cheaply. The Discovery Theme is working on solutions to the first five of these issues, and the "Transforming the Future Mine" Theme is addressing the sixth.
Australian Earth Sciences Convention 2008
212
ABSTRACTS afphabeticaily by surname of presenting author
Resource Mapping: A key ingredient for the mineral resources and development balancing act in South Australia. R. Stuart Robertson^ 'Primary Industries and Resources SA, Minerals and Energy Resources Division, Geological Survey Branch. GPO Box 1671, Adelaide, South Australia 5001 (robertson. stuart@saugov. sa. gov.au) The Adelaide region has excellent geological resources of construction materials. Neoproterozoic (Adelaidean) and Cambrian metasediments uplifted in the Cainozoic to form the present Mt Lofty Ranges are the source of hard rock resources for road construction and concrete aggregate for metropolitan Adelaide. Fault bounded Tertiary basins provide construction and filling sand and brick-making clay. Industrial minerals, such as Cambrian marble used in sodaash production, are important for local manufacturing industries. Copper, lead, zinc and gold mining in the Adelaide region were historically important and metallic mineral exploration and development is currently being revived. Urban development has already 'sterilised' some significant mineral resources close to the city and put pressure on some operating quarries. Problems faced by quarries relate both to the encroachment of residential development and visibility on the fault scarps ('Hills Face Zones') that provide a backdrop for much of Adelaide. Partly in response to these pressures some construction material operations have been established further from the city. The mining of construction sand from a Tertiary palaeochannel on northern Yorke Peninsula, about 130km by road from the city centre is an example. Greater transport distances impose a considerable cost and environmental penalty on construction materials. Even these more distant sources are under threat from conflicting land uses, including growth of regional centres and change of land use from rural to hobby farm/residential use. Paradoxically this peri-urban growth relies on the availability of construction materials at reasonable cost. To enable the full incorporation of mineral resource considerations into planning processes PIRSA Geological Survey Branch has recently commenced a program of mineral resource potential mapping. Although conventional geological mapping underpins this process, the approach adopted is to translate mapping and other resource information into GIS polygons with a straightforward three level categorisation of resource potential and suggested planning response. Although information, particularly drilling information, is often inadequate for Australian Earth Sciences Convention 2008
confident resource estimation the provision of such GIS data is now essential to preserve resource availability.
Fortescue Metals Group Ltd - Creating Shareholder Value from Exploration Stuart Robinson\ Eamon Hannon^and Mark Glassock^ ^ Manager of Exploration, Eortescue Metals Group Ltd ^ Head of Development and Exploration, Eortescue Metals Group Ltd ^ Mining Geology Manager, Eortescue Metals Group Ltd Fortescue Metals Group Ltd (Fortescue) has been an ASX success story over the last 5 years. The market capitalization of the company has gone from $6 milhon July 2003 to about $30 billion as at June 30 2008. While this achievement is due to exceptional performance by all divisions of the company a critical underpin has been the discovery by the Exploration Division of over 2.5 biUion tonnes (Bt) of quahty iron ore in the Chichester Range. Fortescue is now producing from its Cloudbreak deposit in the Chichester Range ramping up to an initial rate of 45 Mt per annum. The Company has announced its intention to increase its production levels four-fold which will require ore sourced from locations other than the Chichester Range. This will require some innovative production scheduling as well as further successful exploration. In 2007 Fortescue announced the discovery of a further 1.7 Bt of Inferred Resources at its Solomon and Serenity projects north of Tom Price. This paper outlines the exploration of the Christmas Creek and Cloudbreak deposits in the Chichester Range and preliminary lessons learned from initial grade control work at Cloudbreak. An initial review of the geology and exploration of the Solomon/Serenity areas is also included.
Spatial variability of mercury distribution in Spanish Islands soil. Jose Antonio Rodriguez Martin\ Manuel Lopez Arias\ Jose Manuel Grau Corbi\ 'LN.LA-CIEOR. Dpto. Proteccidn forestal Carretera de A Coruna 7.5 km. 28040 Madrid. Spain (rmartin@inia.es) Mercury is not abundant in nature, although its presence in soils poses an important risk (Mark and Ralph, 2001). The naturally occurring concentration of mercury in arable soil depends primarily on the geological parent material. However, it has become widespread as a result of many industrial practises that often cause enrichment.
ABSTRACTS 213 alphabeticaify by surname of presenting author
Mercury is a highly toxic environmental contaminant. Human activities, including combustion of fossil fuels, waste incineration and other applications, have significantly increased the emission of Hg into the atmosphere. In general, mercury accumulations in soils are associated with atmospheric deposition (Engle et al., 2005). The anthropogenic emission of Hg is about 60 - 80 % of global Hg emissions. This can remain present in the atmosphere between 0.5 and 2 years before being deposited in the soil (Navarro et al., 1993), and may then be transported over long distances. This study assesses Hg concentration in topsoil, as opposed to its content in the original matter, using geostatistical methods in the two Spanish archipelagos. The Canaries are an archipelago formed by 7 islands of volcanic origin. They are located in the Atlantic Ocean to the southwest of Spain near the Tropic of Cancer and the western Moroccan coastline. The Balearics (limestones) are formed by 4 islands which are located to the east of the Iberian Peninsula and to the extreme west of the Mediterranean Sea. Spatial variation in the Hg content of rocky fragments can be attributed to inherent geographical properties and to geochemical processes, and correspond to mineralogical structures and a bedrock influence. Variations in relation to the Hg concentration in topsoil can be largely attributed to mercury from atmospheric deposition at a large spatial scale. The objectives of this study were to provide a basic understanding of the concentration of mercury in soils and to distinguish the "natural" mercury contribution from that of human-induced pollution in Spanish islands.
How CRC LEME has Provided Breakthroughs in Exploration through Cover-14 Years of Innovative Regolith Geoscience R&D Stephen L Rogers^ ^CRC Landscape Environments Exploration, PO Box 1130, Bentley,
and Mineral 6102
In partnership with our industry end users, regolith geoscience research in CRC LEME has applied the traditionally disparate scientific disciplines of geology, geophysics, geochemistry, soil science, microbiology, molecular biology, biochemistry, hydrogeochemistry, hydrology, plant biology and ecology, to the identification of potential zones of mineralisation and determination of mineral transport and transformation processes in landscapes dominated by cover. Hydrogeochemical techniques to vector in on buried mineralisation, have been successfully trialled in the Tanami and Yilgarn, and the application of high energy X-ray techniques has led to significant advances in gold mineral host understanding. Hyperspectral analysis of surface illite has been identified as a mineralisation vector, and
application of hyperspectral surveys to diamond exploration has aided the discovery of two new kimberlites at Pine Creek SA, employing spectral analysis of HyMap data. The CRCs strategy to focus on biological mechanisms of regolith trace element and mineral transport has delivered significant advances. A highlight has been the isolation of bacteria that precipitates gold in the regolith. The development of phyto-exploration as an effective explorationthrough-cover tool has delivered encouraging results. Highlights include the discovery of an extension to the Pinnacles Pb/Zn lode near Broken Hill, partially the result of a River Red Gum leaf geochemical survey, and the detection of anomalous gold concentrations in leaves of the common native grass Spinifex with the observation that its roots penetrate up to 30 metres down into the regolith. The uptake of uranium and thorium by a variety of native Australian plant species has also been demonstrated by LEME researchers in collaboration with Heathgate Resources, demonstrating that phyto-exploration is a viable method for uranium exploration through cover. In addition the CRC has made significant advances in the dating and understanding of Australian landscape evolution, geochronology and regolith mapping techniques.
Palaeoclimate Driven Eustatic Signature of the Middle Devonian Anoxic Pumilio Event from Reef Complexes of the Emanuel Range, Lennard Shelf Matthew J. Rolfe^ ^School of Earth and Geographical Sciences, University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia (rolfeym @ hotmail com) The reef complexes of the Emanuel Range developed in low palaeolatitudes during late Eifelian to early Erasnian (Middle to early Late Devonian) incipient tectonic subsidence. The reef complexes form an uninterrupted, up to 1 km thick, excellently preserved shallow-platform limestone succession providing a record of palaeoclimate driven highfrequency eustatic, palaeoceanographic and palaeotectonic events. This presentation investigates, using sequence stratigraphy, the relationship between these events and Middle Devonian global anoxic events. Sedimentological investigations of the reef complexes have found that the platform strata consist of two alternating depositional systems. These are: (1) distally steepened ramps; and (2) deep rimmed platforms. Conodont dating has correlated the distally steepened ramp strata with the global late Eifelian Kacak and mid Givetian Pumilio anoxic events and this correlation is confirmed by their
continued next page.. Australian Earth Sciences Convention 2008
214
ABSTRACTS alphabetically by surname of presenting author
variable black carbonaceous (bituminous) mud content, typical of marine anoxic events. Sedimentary fabrics and algal borings of bioclasts have been used to determine the palaeobathymetry of the parasequence facies during these events. The studies indicate that the amplitude of eustatic sealevel change varies across Pumilio event strata from a few tens of meters initially to negligible during the latter half of the event. These results suggest a period of moderate climatic variability occurred coincident with the commencement of the Pumilio Event. Similar patterns of parasequence arrangement have also been interpreted from mid Frasnian distally steepened ramp strata in Belgium.
Granite-Greenstone Associations of the Yamarna - Irwin Hill region, Burtville Terrane, Yilgarn Craton, Australia S.S. Romano , MJ. Pawley\ C.E. Hall\ M.P. Doublier^ , M.T.D. Wingate^ and S. Wyche ' Geological Survey of Western Australia, Cm Hunter & Broadwood Streets, West Kalgoorlie, WA 6430, Australia (sandra.romano@doir.wa.gov.au) ^ Geological Survey of Western Australia, 100 Plain Street, East Perth, WA 6004, Australia Recent 1:100 000-scale mapping in the Merolia and the Yamarna domains, in the eastern part of the Archean Burtville Terrane of the Eastern Goldfields Superterrane (EGST; Cassidy et al. 2006, Geological Survey of Western Australia, Record 2006/8), covered four substantial greenstone belts and several minor areas of greenstones. The domains are separated by the north-northwesterly trending Yamarna Shear Zone. The Irwin Hills - Lake Lightfoot and Ulrich Range greenstone belts in the Merolia Domain have similar lithological assemblages. Both contain mainly mafic to ultramafic rocks, which pass into a basalt-dominated sequence with local interbeds of ultramafic, chert and metasedimentary rocks. The succession at Ulrich Range is also intruded by c. 2660 Ma microgranite sheets. The lower part of the succession in the Mount Venn greenstone belt, also in the Merolia Domain, consists of mafic and ultramafic rocks, with minor sedimentary interbeds. These are overlain by felsic volcaniclastic rocks that grade up into andesitic extrusive rocks and finally into rhyolites, dated at 2770 Ma. The upper part of the succession is intruded by a layered gabbro complex. The Yamarna - Mount Gill greenstone belt in the Yamarna Domain is dominated by a mafic succession with minor ultramafic, clastic sedimentary, and chert components. The belt contains several lens-shaped bodies of felsic volcanic and volcaniclastic rocks that are aligned sub-parallel to the NNW trend. Australian Earth Sciences Convention 2008
The new U - P b zircon SHRIMP ages from the Mount Venn greenstone belt are similar in age to the previously determined protolith ages of gneiss and migmatite in the western Burtville Terrane. These ages, and the c. 2805 Ma age for felsic volcanic rocks in the northwestern Burtville Terrane, have not been encountered elsewhere in the EGST. This suggests that rocks of the Burtville Terrane may have more in common with similarly aged rocks in the Youanmi Terrane farther to the west.
Fighting the Plight: Earth Science on the March in Western Australia James Ross^ ^Earth Science Western Australia Widespread concerns about the national plight of earth science in the Australian Tertiary sector contrast with the positive developments and outlook that now prevails in Western Australia (WA). Whilst the recent remarkable turnaround in demand and pricing of mineral commodities has had a major impact on student numbers, this outlook is also being underpinned by strategic initiatives dating back to 2003, and outhned in this paper. Their common aim is to strengthen earth science in WA commensurate with the State's exceptional resource endowment and strategic needs. Foremost is Earth Science Western Australia (ESWA) which embraces all earth science stakeholders in the State. ESWA focuses on earth science in secondary schools by enabling the new Earth and Environmental Science Course of Study (EES) introduced into upper secondary in 2007. Effective cooperation, and strong industry support, has resulted in 13 EES schools and 240 year 11 EES students in 2007, and 30-38 EES schools and a much larger student cohort in 2008. Continuing increases are anticipated. A complementary initiative targeting lower secondary school science has commenced. Next is the UWA Geoscience Foundation, launched by UWA Geology Alumni in 2004. More than $2.5 million of new funding has been committed for strategic initiatives, including a proposed joint appointment in hydrogeology at UWA and Curtin. UWA and Curtin are also linked in the UWA-based Centre for Exploration Targeting which opened in 2005 with strong support from the State Government and industry. Its research staff of 24 now forms one of the largest applied research groups committed to minerals exploration targeting. UWA and Curtin geoscientists are also supported by an exceptional array of equipment and expertise for geochronology and stable isotope studies at the world ranking De Laeter Centre for Mass Spectrometry, largely based at Curtin. It includes two SHRIMP ion probes and future access t o a C A M E C A 1280.
ABSTRACTS 215 alphabetically by surname of presenting author
A Reassessment of the Evidence for Sulphur-Based Microbial Metabolic Activity in the Early Archean at North Pole, Western Australia. Bruce Runnegar^ and Sorel Fitz-Gibbon^ Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 900951567, U.S.A. ^ Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 900951567, U.S.A. The compositional dispersion among ratios of the four stable isotopes of sulfur has proved to be a window into the nature and behavior of the atmosphere, hydrosphere, and biosphere during the early (Archean) evolution of Earth. However, as more data are accumulated from any particular geological setting, they become increasingly challenging to interpret. Here, we review the evidence from three independent datasets for microbial versus abiological processes in the 3.5 Gaold North Pole succession of Western Australia. One of the crucial parts of the puzzle centers around the interpretation of the host minerals, now barium sulfate (barite), intimately associated with pyrite. We also address the genomic evidence for the early history of sulfur metabolisms.
Mirror Images in East and West Papua Bryan P Ruxton^ ^University of Canberra (janet.palmer-allen @ Canberra, edu.au) The East Papua ultrabasic belt is the mirror image of the West Papuan ophiolite belt though separated by 830km. The nearby Managalase volcanic field has its equivalent in the Minjah volcanic field where shoshonites, calc-alkali suites and lamprophyres are common to both. Both are due to collisional delamination where obduction of oceanic plate played a major role. Underneath lithospheric and asthenospheric mantle underwent heating and expansion with stretching and tearing separating shoshonites in East Papua. It is possible that an original vogesite became under-saturated due to vein-plus-wall-rock assimilation with chromebearing ultrabasic rock and now plots in the middle of the lamprophyre field in the triangular diagram of K2O, AI2O3, MgO. Its whole rock composition is half way between a lamproite and a lamprophyre (Bergman 1987). Events in East Papua are 3-4 million years behind equivalent events in West Papua. In the Managalase volcanic activity has continued into recent time. It includes shoshonite, rhyodacite and an intermediate hybrid "andesite." A compositional gap in the calc-alkali series is filled
by the accidental discovery of a buried dacite lapilli pumice. This pumice is of special interest because near its source it has the same size distribution as experimentally fragmented dacite melt of Mount Saint Helens under rapid decompression from 760°C and 120 bar. The 6500 year old pumice is sparsely phyric with a quenched rind rim. Inside fine vesicles (0.1mm) coarsen to a polygonal centre with cells 5mm across. The cells are stained pink probably due to former iron bearing gases within. Also a higher water content (>2%) led to higher oxygen partial pressure resulting in a greater amount of magnetite dust in some of the pumice lumps. The pumice fall lapilli are well rounded due to shearinduced decoupling of distributed flow along annular fracture walls around a cone ring structure.
Schorlomite and Hydrogrossular in a skarn in the Northern Red Sea Hills. Bryan P Ruxton^ ^University of Canberra (janet.palmer-allen @ Canberra, edu.au) A thick complex lens of norite and some anorthosite at Dirbat well in the northern Red Sea hills intrudes a series of Proterozoic greywacke, andesite and calcareous beds. The resulting skarn has undergone metamorphic differentiation to form beds and lenses of monomineralic wollastonite, grossular hydrogrossular, Schorlomite, idocrase, zoisite, diopside, ilmenite and marble. Some of the marble has a speckled appearance due to granules of forsterite, talc, scapolite, serpentine and galena. Other small lenses include zoisite-calcite, apatitecalcite and serpentine-calcite. In between these lens high grade hornfels of sillimanite, graphite and titaniferous magnetite occur with patches of altered norite looking like lit-par-lit injection. These rocks also contain chlorite, biotite, tremolite, hedenbergite and cordierite. The schorlomite is black, up to 2mm diameter, dodecahedral and magnetic. It contains up to 16% titania. Titania also occurs in sphene, rutile, leucoxene and titaniferous idocrase. The hydrogrossular is green, idiomorphic with some crystals several centimetres in size. The two new features of this skarn are the replacement of hornblende-plagioclase rock by grossular-diopside-wollastonite and the local melting of hydrogrossular some of which still shows flow structure. The northern Sudan is made up of a series of wide strips (terranes) of greywacke and andesitic volcaniclastics aligned northeast-southwest. Several strips are margined by ophiolites marking former island arc obductions at 760Ma. Dirbat Well is in the centre of the Gebeit terrane between Halaib and Port Sudan. The area was regionally continued next page... Australian Earth Sciences Convention 2008
216 ABSTRACTS aiphabetically by surname of presenting author
metamorphosed to greenschist facies in the late Proterozoic. Locally granite intrusions produced hornblende-plagioclase complexes. Epidiorite is typical of much of southern Egypt. Mafic rocks were then intruded and followed by late Precambrian little metamorphosed sediments and acid volcanics.
Consequences of Geohazards on Rock Slope Instability Along a Mountain Road, Southern Saudi Arabia. B.H. Sadagah^
^Engineering and Environmental Geology Department, Faculty of Earth Sciences, King Abdulaziz University, P.O.Box 80099, Jeddah 21589, Saudi Arabia, email, bsadagah@ vahoo.com Mountainous roads are the most difficult project to build in a difficult terrain, Saudi Arabia. The most difficult of which are those high-rising mountains in the southwestern and western parts of the country. The road connects the Red Sea coastal plain at the west with the top of the high-rising mountains, and from there to the eastern part of the country. These descents roads play a vital role in tourism, trading, transportation, security of the Kingdom. Abha-Al-Darb mountain road of almost 50 km long. A 12 km portion of such mountain road that lies along sharp cliff suffers from frequent rock failures, mainly in rainy seasons. The man-made rock slope cuts are 70°-90°. Many of these slopes are dangerous and potentially unsafe due to rockfalls, different modes of rock slope failures especially on rainy days. Failures in both natural and man-made rock slopes are formed mainly of wedge, planar, and toppling failures, and rockfalls. Slope stability analyses were performed to identify the stability/instability zones. Plane and toppling failures, belong to the geologic condition of the genesis. The rock masses are mainly schists, with high grade of metamorphism. The foliation of the schistosity dipping towards the rock slope cuts, causing a frequent occurrence of plane and toppling failures, in spite of the remedial measures which form a continuous problems of instability due to the genesis of the rock mass. The aim of this research is to study 1) the effect of the rock type and the block size on the stability of the rock slopes, 2) the role of geohazards on the slope stability problems at selected parts along Abha-Al-Darb mountain road, in order to identify the hazardous zones, utilizing stereographic projection technique Geographic Information Systems (GIS), and 3) recommend safety measures along the mountainous road.
Australian Earth Sciences Convention 2008
Geological Setting, Mineralisation and Geochronology of Chatree Epithermal Gold-Silver Deposit, Phetchabun Province, Central Thailand Abhisit Salam\ Khin Zaw\ Sebastian Meffre\ Paulo Vasconcelos^, Holly Stein^, Phil Maclntyre"^ ^ CODES ARC Centre of Excellence in Ore Deposits, University of Tasmania, Tasmania, Australia: (asalam @ utas. edu. au) ^Department of Earth Sciences, University of Queensland, ^Department of Geosciences, Colorado State University, Fort Collins, CO 80523-1482 USA Kingsgate Consolidated Limited, Sydney, Australia The Chatree deposit is located on the eastern edge of the Tertiary Chao Pray a Basin, lying within the Loei Fold Belt. Low-sulphidation epithermal gold-silver mineralisation at Chatree occurs as veins/veinlets and stockworks with minor breccias hosted by volcaniclastic and volcanic sedimentary rocks of andesitic to basaltic andesite composition. Lithologic and petrographic studies indicate that the Chatree volcanic and volcanic sedimentary host sequence can be divided into porphyritic andesite (lava flow), fiamme breccia, monomicticpolymictic and volcanic sedimentary and epiclastic rocks. Five mineralisation stages have been recognised at Chatree based on textural and crosscutting relationships and mineral assemblages: Stage 1 - silica breccia filling and viens/veinlets; Stage 2 quartz + carbonate ± chlorite ± adularia - sulphide electrum veining; Stage 3 - quartz + carbonate ± adularia + chlorite + epidote ± sulphide; Stage 4 quartz ± carbonate veins/veinlets; and Stage 5 zeolite - quartz - carbonate veins/veinlets. The timing of emplacement of the volcanic rocks (coherent lava and volcaniclastic rocks) which host the epithermal gold-silver mineralisation in the Chatree area was constrained from the age of feldspar phyric andesite which yields a LA ICP-MS U-Pb zircon age of 250 + 6 Ma (Early Triassic). Adularia from Stage 2 (ore-bearing stage), was dated by laser incremental-heating ^^Av/^^Ar analysis, and it yields an age of 250 ± 0.8 Ma (Early Triassic). The minimum age of epithermal mineralisation can be bracketed by the ages of two post-mineralisation dykes (xenolithic granodiorite in basaltic dyke and hornblende diorite dyke), which yield LA ICP-MS U-Pb zircon ages of 238 + 6 Ma (Middle Triassic) and 244 + 7 Ma (Early Triassic), respectively. Re-Os dating of molybdenite from sub-economic porphyrystyle mineralisation at the 'N' Prospect, located about 1 km south of the Chatree epithermal deposit, yields an age at 244 ± 1 Ma (Early Triassic), which suggests that the Chatree gold-silver epithermal deposit pre-dates the 'N' porphyry mineralisation.
ABSTRACTS alphabetically by surname of presenting author
Investigation of Guno storm and their effects on Coastlines Geomorphology of Oman Sea. A.R.Salehipour^ K.Nejad Afzali^ ^Geological Survey of Iran, Marine Geology Management, Marine & Coastal Geomorphology and Hydrodynamic Group (Ar.salehipour@gmail.com) The Gunu storm, due to its severe intensity, caused substantial damages to the coasts of Sistan and Baluchestan and Hormozgan providencesS. Tropical storms develop in the form of enormous hurricanes which suck the surrounding air towards them. We feel such rapid movement of air as strong winds; in satellite images, it is seen as the movement of clouds (water vapor) towards the core or the eye of the storm. With a velocity of 150 km/h and rain reaching 160 mm, the storm has made considerable geomorphologic changes in the coast of Oman gulf as well as damages. Such geomorphologic changes were studied using ETM, TM and LISS III satellite data and were compared before and after the Guno storm. Also the early results taken from satellite images were coordinated with field Study after the storm. These inquiries show that acute changes have been made in the opening of important estuaries such as Shur, Sorgan, Kahir, Bir and Bandini. Also change of river way due to migration channel on river meander and limitation of flooded area on coastal plain was determined. Cooperation of satellite data shows, discharge of sediment to the bays such as Pozm, Chabahar that it can be a serious problem for navigation and coastal structures in this area
Timing of the Lawn Hill Impact Crater and Relationship to the Century Zn-Pb Deposit, Northwest Queensland Jess A. Salisbury^ Andrew G. Tomkins^ and Bruce F. Schaefer^ School of Geosciences, PO Box 28E, Monash University, Melbourne VIC 3800 Jess. Salisbury @ sci. monash. edu. au Andrew. Tomkins @ sci. monash. edu. au Bruce. Schaefer@sci. monash. edu. au The Lawn Hill circular structure contains unambiguous evidence for an extraterrestrial impact into a Mesoproterozoic basement, including planar deformation features in quartz, impact diamonds, shatter cones and impact melt breccias. Interestingly, the giant Mesoproterozoic Century Zn-Pb deposit is situated at the intersection of this impact structure and the 100+ km Termite Range Fault, enticing the thought that its genesis may be tied to the impact event. The annulus of low hills that defines that shape of the impact structure consists of Cambrian
limestone, which we have found to contain features indicating that it was impacted, including (1) extremely convoluted folding and brecciation compared with the flat lying and undeformed nature of the limestone away from the structure, (2) the presence of limestone breccia "dykes" penetrating hundreds of meters into the Century deposit, and (3) the presence of a 1 Mt megaclast of Century ore encapsulated within the limestone. The highly convoluted fold structure within the limestone annulus suggests that this unit was wet or only semiconsolidated during impact, and may represent slump-filling of an annular trough in response to impact-induced partial liquefaction of a thin sediment veneer. This suggests a timing for impact concurrent with, or shortly after, limestone formation. Preliminary "^Vr/^^Ar isotope dating, performed on samples of impact melt glass and K-feldspar spherules from the centre of the crater, gives ages of 483.6 + 1.6 Ma and 477.9 + 1.2 Ma respectively, which suggest an earhest Ordovician age for impact. Thus, formation of Century is found to be unrelated to impact-generated hydrothermal activity, although some minor hydrothermal chemical remobilisation of metals did occur. In addition, however, macro-scale physical remobihsation of gigantic ore fragments did occur, driven by impact-induced lateral and vertical injection of limestone into the Proterozoic sediments.
The Formation and Early Evolution of the Solar System Raquel Salmeron^ ^The Australian National University Star formation is induced by the gravitational collapse of molecular clouds cores. During this phase, angular momentum conservation results in the progressive increase of the centrifugal force, which eventually halts the collapse and leads to the development of a central mass ("protostar") surrounded by a disk of material. In the presence of an angular momentum transport mechanism, mass accretion onto the protostar proceeds through this disk, and it is believed that this is how stars typically gain most of their mass. The mechanisms responsible for this transport of angular momentum are not well understood. The most promising are turbulence viscosity induced by the magnetorotational instability and the centrifugal acceleration of outflows. Both processes are powered by the action of magnetic fields and are, in turn, likely to play key roles in the structure, dynamics and evolution of protostellar disks. For example, magnetically-driven turbulence may impact disk chemistry and the properties of dust grains mixed with the gas. Magnetic resonances alter the tidal torque exerted by the disk on a forming planet and can modify the speed -and direction- of its migration through the disk. Finally, the magnetically inactive ("dead") zones are the regions where planets are
continued next page..
Australian Earth Sciences Convention 2008
217
218
ABSTRACTS alphabetically by surname of presenting author
thought to form, and have also been invoked as a mechanism to stop their inward migration. The weak ionization of protostellar disks, however, may prevent the magnetic field to effectively couple to the gas and drive these processes. In order to study the magnetic activity of these disks under realistic conditions, we have developed a quantitative scheme that incorporates their detailed ionization structure and all relevant field-matter diffusion mechanisms. In my talk I examine the viability and properties of magnetically driven processes in protostellar disks, present our solutions and explore the implications of the resulting disk structure to planet formation and migration.
The Tilting Continent and Other Geomorphic Signals of Mantle Flow Beneath Australia Mike Sandiford^ 'School of Earth sciences, University of Melbourne (mikes @ unimelb. edu. au) Large-scale flow of mantle should produce a dynamic topographic expression that causes progressive downward tilting of continents as they approach zones of long-lived convergence. A -300 m continental scale tilting over the last - 1 5 myrs explains many hitherto enigmatic aspects of the Australian Cainozoic stratigraphic record which in turn provides and important constraint on the amplitude of the dynamic topographic signal and warns about the difficulties in extracting long-term eustatic sea level records. Deciphering even more subtle surface deflections (amplitude 100 m, wavelength 100-1000 kms) caused by small-scale convection in the upper mantle has proved difficult because they are small compared those associated with isostatic compensation of loads within or on the lithosphere. In the Australian continent, extraordinarily flat landscapes, combined with low rates of lithospheric deformation, extremely inefficient fluvial regimes, and the absence of widespread glaciation, have meant that it ideally suited to seeking such dynamic signals. Transient dynamic surface deflections of appropriate spatial scale and characteristic timescale of ~1-10 milhon years, are indicated by tracking the record of past megalake and marine shorelines, thereby providing geomorphic tracers of the growth and detachment of convective instabilities from the upper thermal boundary layer beneath the northward moving Australian plate, as well as the relative direction of mande flow. Understanding the subtle pattern of landscape alteration, that has caused significant rearrangement of drainage patterns, helps explain hitherto enigmatic biodiversity of Australia's inland faunas, and provides new clues to understanding distribution of strategic metal reserves such as sedimentary U-deposits and other placers. Australian Earth Sciences Convention 2008
Collie Coal Technology.
and
the
Clean
Coal
Krishna K. Sappal ^ Department of Applied Geology, Curtin University of Technology, Australia (K. K. Sappal @ curtin. edu. au) The Early to Late Permian coal of the Collie Group, Collie Basin is referred to as the Collie Coal. The bilobate intracratonic Collie Basin is located 160 km south south east of Perth, Western Australia, and the coal has been mined since 1883.The identified coal resources of the basin are 2.1 BT, and the current open cut production is 6MT, and mostly it is used for power generation at Muja. The extractable coal resources exceed 500MT for open cut mining and 320 MT for underground methods. Besides Collie Coal, other substantial Permian coal has been identified in the Vasse Shelf of the Perth Basin. The coal has subdued lustre due to fine laminations of lithotypes, and the dominance of dull and dull banded lithotypes with minor bright, bright banded and fusinous types.The maceral composition of the coal is variable from seam to seam and even with the seam, the macerals of vitrinite and inertinite groups dominate, and the exinite macerals and mineral matter is low. Overall lithotypes have low concentrations of ash, sulphur and the trace elements. The vitrinite reflectance has a range between 0.42% to 0.47%, and the coal ranks as subbituminous as per the Australian Classification. On the basis of organic petrology, inter seam sediments, flora and the very low concentrations of boron, the depositional environment postulated for the coal is braided, fluvial and fluvio-lacustrine with marked fluctuations in the water table, as marked by the presence of fusain and inertodetrinite in the coal. The clean coal technologies for the reduction in the green house gas emissions during utilisation of the coal include Integrated Gasification Combined Cycle (IGCC), Coal Seam Gas (CSG), Geosequestration and the Pressurised Fluidised Bed Combustion (PFBC).
Hydrogeology of the Leederville aquifer near Margaret River David Schafer\ Seth Johnson^ 'Department WA, 6000 ^Department WA, 6000
of Water, 168 St Georges Tee, Perth, (david.schafer@water.wa.gov.au) of Water, 168 St Georges Tee, Perth, (sethfohnson@water.wa.gov.au)
A groundwater investigation has been undertaken to reassess the groundwater allocation limits for the Leederville aquifer in the Cowaramup groundwater subarea to the east of Margaret River.
ABSTRACTS alphabettcaffy by surname of presenting author
Fourteen investigation/monitoring bores were drilled into the Leederville Formation in 2006. The Leederville Formation is a Cretaceous sequence consisting predominantly of discontinuous, interbedded sandstone, siltstone and shale. Some conglomerate beds occur at the base of the formation and fine organic sediments and lignites occur near the top. The Leederville Formation forms a major aquifer in the southern Perth Basin. Results from previous coal exploration drilling were combined with the new drilling results to improve the understanding of stratigraphic relationships of the Leederville Formation. A comprehensive geological model was constructed using the 3-D visualisation package PETREL. Geophysical logs in combination with the Uthological logs and palynology results were used to subdivide the Leederville Formation into six distinct members (Yelverton, Lower Vasse, Upper Vasse, Lower Mowen, Upper Mowen, and Quindalup). Hydrochemistry and isotopic groundwater age studies complement the drilling investigation. Carbon-14 groundwater ages enabled identification of an area of higher recharge on the Blackwood Plateau. Water-rock processes such as the formation of bicarbonate with depth and sulphide oxidation are currently being analysed by PHREEQC modelling of the water chemistry results. Initial results indicate there is a sharp redox/pH interface above which sulphide oxidation occurs and below which bicarbonate forms. The geological model was a major input for a MODFLOW numerical groundwater model. Sand percentage contour maps for each of the members of the Leederville aquifer were generated using the PETREL software based on lithological logging and borehole gamma. The sand percentage distributions were used as a proxy for the distribution of hydraulic conductivity in the groundwater model. A number of model scenarios were simulated. These included the sustainability of current abstraction, effects of increasing allocation limits in the Cowaramup groundwater subarea and impacts on groundwater dependent ecosystems. From the modelling results recommendations were made regarding the reassessment of the groundwater allocation limits for the Leederville aquifer for the horticultural and viticultural industries.
Structural Controls on Mineralisation At the Wyoming Gold Deposits, NSW: Inferences From Deformation - Fluid Flow Numerical Models. P.M. Schaubs^ P.A. Roberts^ D. 1. Chalmers^ T.W. Ransted^ and D.G. Meates^ ^ pmd^CRC, CSIRO Exploration & Mining, PO Box 1130, Bentley, WA, 6102 (Peter.Schaubs@csiro.au) ^Alkane Resources Ltd., PO Box 8178, Perth Business Centre, WA, 6849 (ichalmers@alkane. com.au) The Wyoming prospects are located approximately 40km north of Parkes, NSW and lie within the Tomingley Gold Project which Alkane Resources Ltd. has developed over the last 7 years. Mineralisation occurs within a series of andesitic feldspar porphyry intrusions which are surrounded by volcaniclastic sandstones and siltstones. Within the Wyoming One porphyry (WYl), mineralisation occurs throughout the porphyry but is associated with sericite-carbonate alteration, steeply dipping (NNE) quartz veins and a number of E-W striking, steeply dipping faults. Mineralisation also occurs in adjacent carbonaceous mudstones whose orientation parallels the overall NNW strike of the contact with the porphyry. In contrast to WYl, the nearby Wyoming Three (WY3) porphyry is thicker and mineralisation is only associated with a cross-cutting shear zone. Numerical models of the WYl porphyry were designed to establish the stress fields under which folding of the adjacent NNW striking stratigraphy, vein formation within the porphyry, and fault movement could have occurred. Field observations and numerical modelling results show that E-W contraction was most likely responsible for the folding of the stratigraphy. The formation of steeply NNE dipping veins, precipitation of gold and movement on E-W striking faults, however, is interpreted to be synchronous with sinistral transpression. This is consistent with the orientation of inferred structures in the Tomingley area. Generic numerical models were aimed at determining the effects of porphyry shape and size on the formation of tensile fractures and zones of dilation. These models show that dilation and tensile failure occur in the thinnest portions of porphyry regardless of plunge. Thin porphyries are more likely to fracture throughout, while thick porphyries fracture only at the contact with the surrounding matrix. This may be one reason why the thin WYl porphyry contains more mineralisation than the thicker WY3.
Australian Earth Sciences Convention 2008
219
220 ABSTRACTS alphabetically by surname of presenting author
A Parametric Study of Overriding Plate Shortening and Extension Above Subduction Zones: Explaining The Formation of The Andes. W. P. Schellart^ ^ School of Geosciences, Monash Melbourne, VIC 3800, (wouter.schellart@sci. monash. edu. au)
University, Australia
The Andes mountain belt in South America formed above a subduction zone and is the type example of a non-collisional orogen. Such mountain building above subduction zones is enigmatic, and the key parameter controlling the underlying dynamics remains a matter of considerable debate. A global survey of subduction zones is presented, illustrating the correlation between overriding plate deformation rate and twelve physical parameters: overriding plate velocity, subducting plate velocity, trench velocity, convergence velocity, subduction velocity, subduction zone friction, subducting plate age, lateral slab edge proximity, ridge subduction, subduction polarity, shallow and deep slab dip. All correlation coefficients are low (|R| < 0.38), irrespective of the "absolute" reference frame, relative plate motion model or overriding plate deformation model, except for the trench velocity (0.32-0.68) and subduction velocity with an anticorrelation (0.55-0.57). This implies that no individual parameter can explain overriding plate deformation, except that trench retreat corresponds to extension while a -stable trench or trench advance corresponds to shortening. Understanding of the variety of strain patterns is obtained when slab edge proximity and overriding plate velocity are combined. Orogenesis occurs in overriding plates bordering central regions of wide subduction zones (> -4000 km) when the overriding plate is moving trenchward at 0-2 cm/yr (e.g. Andes, Japan). Because the centre of a wide slab offers large resistance to lateral migration, the overriding plate effectively collides with the subduction hinge, forcing the slab to attain a shallow dip angle (e.g. Nazca and Japan slabs). Overriding plate extension is only found close to lateral slab edges or during overriding plate motion away from the centre of a wide subduction zone.
Constraints From Subduction Models On Mantle Flow Patterns and The Slab To Mantle Viscosity Ratio. W. P. Schellart^ ^School of Geosciences, Monash Melbourne, VIC 3800, (wouter. schellart@sci. monash. edu. au)
University, Australia
Three-dimensional fluid dynamic laboratory simulations are presented that investigate the subduction process with upper mantle models and deep mantle models, and for various subducting Australian Earth Sciences Convention 2008
plate/mantle viscosity ratios (r|sp/r|M = 59-1375). The models investigate the mantle flow field, geometrical evolution of the slab, sinking kinematics, and relative contributions of subducting plate motion and trench migration to the total rate of subduction. All models show that the subducting plate is always moving trench-ward resulting from slab pull. Furthermore, all deep mantle models show trench retreat, as do upper mantle models in the initial stage of subduction before slab tip-transition zone interaction. Upper mantle models with a low rjsp/'HM (66, 217) continue to show trench retreat after interaction. Upper mantle models with a high 'nsp/'HM (378, 709) show a period of trench advance after interaction followed by trench retreat. Upper mantle models with a very high r|sp/riM (1375) show continued trench advance after interaction. The difference in trench migration behavior and associated slab geometries is attributed to both rjsp/TlM and the mantle depth to plate thickness ratio TulTs,?, which both affect the slab bending radius to mantle thickness ratio r^ITu- Four subduction regimes can be defmed: Regime I with r^lT^ < -0.3, trench retreat, slab draping and a concave trench; Regime II with -0.3 < r^/Tu < ~0.5, episodic trench migration, slab folding and a concave trench; Regime III with r^ITu - 0.5, trench advance, slab roll-over geometries and minor trench curvature; Regime IV with r^ITu > ~0.8, trench retreat, slab draping and a rectilinear trench. Finally, comparison between the slab geometries observed in the upper mantle models and slab geometries observed in nature imply that the effective viscosity ratio between slab and ambient mantle in nature is less than 10^ and of the order 1-7 x lOl
Discovery of a Fossil Slab in the Lower Mantle Below The Tasman Sea Using Plate Reconstructions And Mantle Tomography. W. P. Schellart\ B. L. N. Kennett^ W. Spakman^ M. Amaru^ ^ School of Geosciences, Monash University, Melbourne, VIC 3800, Australia (wouter. schellart@sci. monash. edu. au) ^ Research School of Earth Sciences, The Australian National University, Canberra, ACT 0200, Australia ^ Department of Earth Sciences, Utrecht University, Utrecht, The Netherlands Traditional models for the Cenozoic evolution of the Southwest Pacific region include two distinct subduction zones, a northwest-dipping subduction zone in New Caledonia and a southwest-dipping subduction zone in the Northland region. In more recent tectonic models the Northland and New Caledonia regions are interpreted to bear the hallmarks of a -2500 km wide fossil northeastdipping subduction zone along which the South Loyalty Basin was subducted (Crawford et al, GSASP 22, 37-397, 2003; Schellart et al., Earth-Science Reviews 76, 191-233, 2006). Eocene-Early Miocene volcanic activity along the Loyalty-Three Kings-
ABSTRACTS alphabetically by surname of presenting author
Northland plateau seamount chain is interpreted as arc volcanism and its timing constrains subduction activity. Post-subduction and syn- to post-obduction Late Oligocene to Early Miocene volcanism in New Caledonia, Northland and the Norfolk Basin is interpreted as slab-detachment induced volcanism, and therefore constrains the timing of slab detachment (Schellart, Terra Nova 19, 211-218, 2007). Such data thus constrain the longevity of subduction and the timing of slab detachment. The geological and geochronological data have been incorporated into regional tectonic reconstructions and coupled to different "absolute" global reference frames to be able to predict the geographical location and depth of the detached South Loyalty slab. Global S-wave and P-wave tomography models have been used to see if the predictions fit with the regional tomography. It is found that the S-wave and P-wave models show a good agreement between predicted and observed slab signature in terms of geographical location, size, geometry and depth. The agreement between the plate reconstructions and mantle tomography provides strong support for the existence of a continuous 2500 km wide subduction zone and negates earlier models involving two distinct subduction zones. The agreement also provides constraints on the viscosity of the lower mantle and lower mantle sinking velocities.
Subduction Zone Dynamics on Earth: Insight From Geodynamic Models, Kinematic Calculations And Observations Stegman^, L. Moresi^
J. Freeman^ D. R.
^ School of Geosciences, Monash University, Melbourne, VIC 3800, Australia (wouter. schellart@ sci. monash. edu. au) ^ Bureau of Meteorology, Melbourne ^ School of Mathematical Sciences, Monash University, Melbourne, VIC 3800, Australia A key first-order observation of the plate tectonic behaviour on Earth is that subducting plates move trenchward, thereby accommodating subduction. Another first-order observation is that subduction zone plate boundaries (i.e. the trenches and their associated hinges) migrate across the globe, and thus also accommodate subduction. Recent estimates indicate that -25% of global rate of subduction is realized by such trench retreat (Schellart et al., Nature 446, 308-311, 2007). Furthermore, some -75% of the subduction zones retreat, while -25% advances. There is a general geodynamic consensus on the underlying driving force of subducting plate motion. Observational studies, analytical calculations and geodynamic modelling indicate that such motion is caused by a pull force that is exerted by the subducted slabs to their trailing plates at the
surface. Indeed, it is thought that subducted slabs are the main driving force for plate tectonics and mantle convection on Earth. For the diversity of trench migration velocities observed on Earth, there appears to be no general consensus on the primary physical parameter(s) that is(are) responsible for such diversity, and the last few years have seen a plethora of conceptual and geodynamic models. In this keynote presentation, a review will be presented of geodynamic models and plate kinematic models from the past -20 years. Many insights have been obtained from both numerical and laboratory models of subduction. In addition, many insights have been obtained from global subduction zone studies that focus on their kinematics or geometry, and from regional and global plate reconstructions. New results from geodynamic modelling and global kinematic calculations will be presented, which imply an important role for the width (trench-parallel extent) of subduction zones, the slab to mantle viscosity ratio and the mantle depth.
The Crustal Evolution of the Musgrave Province. Ailsa Schwarz^'^, Martin Hand^, Karin Barovich^, Ben Wade^, Elena Belousova^ Elizabeth Jagodzinski^ ^Department of Primary Industries and Resources of South Australia, GPO Box 1671, Adelaide, South Australia 5001, (schwarz.ailsa@saugov.sa.gov.au) Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide South Australia 5005 ^GEMOC, Department of Earth and Planetary Sciences, Macquarie University Sydney, NSW 2109
The Musgrave Province, central Australia, separates the three main crustal elements of Proterozoic Australia: the Northern, Southern and Western Australian Cratons. Restricted access to key locations, combined with overprinting effects of the pervasive upper-amphibolite to granulite facies Musgrave Orogeny {ca. 1230-1150 Ma), has limited our understanding of the earliest stages of the Province's crustal development. Metasedimentary rocks deposited prior to the Musgrave Orogeny are common throughout the Province. Determination of their provenance utilising robust isotopic, geochronological and geochemical tools provides insight into the crustal evolution of their source regions during an enigmatic time interval in the evolution of the region. Whole rock Sm-Nd isotopic analyses of metasedimentary rocks give 8Nd(1300 Ma) values ranging from -10.1 to -0.2 (n=28), and TDM values ranging from 2800 - 1840 Ma. In situ Lu-Hf zircon analyses suggest two distinct source regions. Metasedimentary rocks appear to be derived either from a comparatively isotopically juvenile source terrain, with the majority of Snf TDM (crustal) values ranging from 2200 - 1500 Ma, or from a comparatively older and increasingly isotopically continued next page.. Australian Earth Sciences Convention 2008
221
222
ABSTRACTS alphabeticaify by surname of presenting author
evolved reworked source, with the majority of enf TDM (cmstal) values ranging from 3200 - 2500 Ma. Partial recrystallisation of inherited zircons during granulite facies metamorphism resulted in variable Pb loss, but the bulk of analyses were <10% discordant. This incomplete resetting of the U-Pb system was concealed because the resetting event formed a line of discordia near parallel to concordia. In contrast, Lu-Hf in zircon is far less susceptible to alteration resulting in the decoupling of the U-Pb and Lu-Hf systems. Consequently the combination of in situ zircon U-Pb and Lu-Hf isotopic data not only provide a powerful tool to discriminate between discrete source regions, but also allow for discrimination between accurate ages and those affected by Pb loss during high grade metamorphism.
3D Modelling and The Implications For Resource Assessment. Margaretha Scott^ ^Geological Survey of Queensland, Department of Mines and Energy, Indooroopilly, 4068, Brisbane. (margaretha. scott@dme. qld.gov. au) Mineral resource assessments have a long history and are associated with a large number of methodologies. The estimation methodology adopted by the Geological Survey of Queensland (GSQ) reflects a number of factors, the most critical being the relationship between GSQ products and its main client groups. Resource assessments have the potential to provide a number of different outputs. The products that are released as part of the GSQ assessments aim to maximise gains to the State both by stimulating effective exploration investment as well as supporting government planning processes. The estimation procedure used is based on the USGS three-part assessment process. This framework is designed to: (1) be applied over large regions, (2) maximise information conveyed by incorporating geological uncertainty, and (3) provide results that can be included in economic analyses aimed at assessing the risks and potential financial returns associated with mineral development within large land parcels. A major advantage of this methodology is its flexibility in regard to the information that can be used, lending itself to incorporate advances in technology and applications. A significant modification to the three-part assessment process by the GSQ has been the incorporation of 'prospectivity' modelling. 'Prospectivity' modelling provides detailed analysis of deposit favourability, which is then used to support estimates of undiscovered resources. Importantly, this modelling is also used to develop exploration models and test new concepts which can have a major impact on perceptions of prospectivity and the re-invigoration of exploration, much in the same way as the release of new geoscientific data. The Northern Drummond Resource
Assessment is an example of how formal quantitative assessment processes have incorporated 3D-GIS and modem 2.5 and 3D numerical modelling to explore the various geological aspects considered to be important in the genesis of epithermal deposits and test structural scenarios aimed at developing better constrained exploration models.
Resource Assessment in The Drummond Basin, Developing New Concepts. Margaretha Scott^ Melanie Fitzell\ Kate Wilkinson \ Owen Dixon \ Leonardo Feltrin ^Geological Survey of Queensland, Department of Mines and Energy, Indooroopilly, 4068, Brisbane. (margaretha. scott @ dme. qld. gov.au) School of Earth and Environmental Sciences, James Cook University, 4811, Townsville. (Leonardo. Feltrin @jcu. edu. au) The Northern Drummond Resource Assessment is incorporating 3D-GIS reconstructions and numerical modelling (UDEC, FLAG 3D and WofE) to develop a better understanding of the local controls on epithermal mineralisation. Epithermal deposits are characteristically associated with subaerial volcanic fields, with mineralisation located in structurally and permeability focused fluid flow zones. 3D architecture and modelling of fluid flow processes provides opportunities to test a number of local relationships and structural scenarios. Construction of the 3D architecture necessitated the development of stratigraphic, magmatic and structural frameworks. A space-time plot summarised stratigraphic relationships and tectonic events, as well as highlighting an association between changing basement stratigraphy and structural domains. A more comprehensive picture of magmatic activity was generated by combining the existing knowledge of intrusive outcrops with an interpretation of potential field data (aeromagnetics and gravity) to identify and classify intrusives undercover. Depth constraints for these bodies were generated in ModelVision. A comparison of existing structural models with results of recent mapping and newly generated datasets ('worms') revealed inconsistencies. As a consequence, the reevaluation of constraints to the architecture of the basin became a prerequisite to the numerical modelling phases. As the basin is extensively overlain by younger sediments and volcanics, the interpretation of the structural architecture relied heavily on an understanding of the outcropping regions and extrapolating undercover using potential field data and where available seismic data.
ABSTRACTS alphabetically by surname of presenting author
Key datasets underpin the scenario that was developed to constrain pre-, syn- and postepithermal structures, their kinematics and their relationship to the stratigraphic architecture of the basin and related magma emplacement. We subdivide the deformational history of the basin into two rifting events and at least two phases of compressional deformation. Structural domains reflect the partitioning of deformation across the northern basin, which has variously favoured the development of early extensional features and in other regions compressional structures.
Exploring for Porphyry Cu-Au-Mo in the Gilmore Fault Zone at Temora, NSW Martin M. Scott^ ^Goldmineo Corporation PO Box 2403 Orange 2800. (martin. seott@goldmineo. eom) North of Temora NSW, the Gilmore Fault Zone and Gidginbung Volcanics are mosdy obscured by regolith. Oriented drillcore is important for obtaining geological information, particularly for solving whether the Gilmore Fault Zone dips to the ENE or WNW in this area. There are two geological units of interest, the Ordovician - Early Silurian Gidginbung Volcanics and the Siluro-Devonian Ootha Group. The Gidginbung Volcanics consist of andesitic volcaniclastics intruded by hornblende gabbro, diorite to tonalite, and late stage monzodiorite dykes to sills with associated porphyry Cu-Au-Mo mineralisation at numerous prospects. Typically the mineralisation is low grade chalcopyrite, molybdenite, gold and rare bornite, although the new Monza prospect contains a high grade intercept of 12.7m @ 8.88% Cu, 6.15 g/t Au, 85 g/t Mo around porphyritic monzodiorite. Porphyry prospects are aligned along a NNW-SSE trend, parallel to the Gilmore Fault Zone. Plunging shallowly to the NNW or SSE are stockwork vein axes for porphyry-style mineralised quartz-pyrite seam veins, and beta (p) axes for monzodiorite contacts. Along the same trend and adjacent to faults with the Ootha Group at the Yiddah and The Dam prospects, cleavage in the Gidginbung Volcanics dips steeply ENE. Mineral lineations on veins, cleavage and faults at numerous prospects indicate strike slip movement, both dextral and sinistral. Bedding and cleavage in the Ootha Group also typically strike NNW-SSE parallel to the Gilmore Fault Zone, cleavage dips steeply ENE, and folds plunge shallowly N-S and verge west. These structural orientations and quartz tension veins indicate sinistral strike slip fault movement of the Ootha Group and adjacent Gidginbung Volcanics by the Gilmore Fault Zone in the Devonian. Concluding, faults of the Gilmore Fault Zone
north of Temora dip steeply ENE, displacing the Gidginbung Volcanics and Ootha Group by strike slip. Porphyry Cu-Au-Mo mineralisation and monzodiorite intrusions are oriented NNW-SSE, parallel to the Gilmore Fault Zone.
Opening up New Base Metals, Uranium and REE Provinces in Central Australia Through Pre-Competitive Geoscience Ian Scrimgeour^ Dorothy Close^ ^ Northern Territory Geological Survey, GPO Box 3000, Darwin NT 0801 (ian. scrimgeour@nt.gov.au ) The Northern Territory remains highly prospective and underexplored, and a wealth of geoscientific data is available to explorers looking to unlock its greenfields potential. The Northern Territory Geological Survey (NTGS) retains a strong focus on getting geologists into the field to collect baseline geological and geochemical data and provide improved geological frameworks, backed up by regional gravity acquisition, 3D modelling and geochronology. This forms the basis for the NT Government's 4 year, $14.4 million 'Bringing Forward Discovery' initiative. A high priority for NTGS in recent years has been to develop a comprehensive geological framework for the complex Palaeoproterozoic Arunta Region in central Australia. The Arunta Region is interpreted as a long-lived Palaeoproterozoic plate margin that was subjected to widespread reworking and fluid flow in the Palaeozoic. New NTGS geoscience is identifying discrete tectonic domains and basin packages that is providing industry with the critical understanding required for effective targeting and discovery. This is being further enhanced by a current program to complete regional gravity coverage over the entire Arunta by mid-2009. NTGS interpretations suggest the existence of a significant zone of rare earth element anomalism in the Arunta Region, along with high potential for base metals and uranium in areas that have undergone little or no modern exploration. This has the potential to become one of Australia's significant mineral provinces. NTGS is further promoting the Territory's greenfields prospectivity through new drilling and geophysical partnerships with industry, and is now increasing its focus on the untapped potential of shallow basement beneath the Territory's widespread Cambrian and Mesozoic basins.
Australian Earth Sciences Convention 2008
223
224 ABSTRACTS alphabetically by surname of presenting author
Crustal to Lithospheric-Scale Structure of the Capricorn Orogen from Magnetotellurics
3D Magnetotelluric Array Measurements Over the Olympic Dam and Carrapateena Regions, South Australia
K. S e l w a y \ S. Sheppard^ A.M. Thorne^ S.P. Johnson^ P.B. Groenewald^
K. S e l w a y \ G. H e i n s o n ^ D. Giles^ L. Vella^ J.A. de W e t ^ M . C a w o o d ^ N. H a y w a r d ^ R. Gill^
^ Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia. (katherine. selway @ adelaide. edu. au) ^ Geological Survey of Western Australia, Mineral House, 100 Plain Street, East Perth, 6004. WA (Steve, sheppard @ doir. wa. gov.au) The Capricorn Orogen in Western Australia is one of the best-exposed Proterozoic orogens in Australia. It includes reworked crust of the Archean Yilgarn and Pilbara Cratons, and metamorphic and granitic rocks of the Gascoyne Complex, which comprises latest Archean to Paleoproterozoic rocks of the Glenburgh Terrane in the south, and Paleoproterozoic rocks in the centre and north. Gascoyne Complex rocks are unconformably overlain by Mesoproterozoic sedimentary deposits of the Edmund and Collier Basins. The Capricorn orogen is widely interpreted as the product of collision between the two Archean cratons, with the suture in the centre of the complex marked by the Minnie Creek batholith. A 300 km-long magnetotelluric (MT) survey was conducted across the Capricorn Orogen to increase our understanding of the juxtaposition of these crustal elements by obtaining information about their electrical structure with depth. Phase tensor analysis of the data showed that 2D MT inversion could only be carried out for stations in the centre of the profile, crossing the Gascoyne Complex. The model shows that there is no electrical distinction between the Glenburgh Terrane and the remainder of the Gascoyne Complex, and that the Glenburgh Terrane is distinguishable from its bounding cratons. Therefore, we infer that the Glenburgh Terrane forms basement to the whole Gascoyne Complex, and that there is no suture in the centre of the complex. 3D forward modelling carried out for the entire survey line, incorporating the basement blocks as well as the surrounding ocean and sedimentary basins is most consistent with a model in which the margin between the Glenburgh Terrane and the Yilgarn Craton (the Errabiddy Shear Zone) dips south, with crust of the Glenburgh Terrane wedged beneath the northern Yilgarn Craton. Forward modelling also suggests that the boundary between the Gascoyne Complex and the Pilbara Craton to the north is a steeply dipping structure beneath the Edmund and Collier Basins that may correlate with the Taiga Fault.
Australian Earth Sciences Convention 2008
^ Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide ,5005 (katherine.selway@adelaide.edu.au) ^ Centre for Mineral Exploration Under Cover, School of Earth and Environmental Sciences, University of Adelaide, SA 5005, (david.giles@adelaide.edu.au) ^ Teck Cominco Australia Pty. Ltd., PO Box 91, Belmont, WA 6104 (lisa.vella@teckcominco.com) ^BHP Billiton Ltd. 180 Lonsdale Street, Melbourne, VIC, 3000 (barry.dewet@bhpbilliton.com) The eastern Gawler Craton/Stuart Shelf region is one of the most prospective mineral provinces on Earth and houses both the Olympic Dam and Carrapateena lOCG deposits. However, the mineral systems and the crustal architecture that provides their framework are poorly understood because the (ca 1590 Ma) prospective rocks are largely covered by Neoproterozoic-to-recent sediments. To address this, long-period and broadband magnetotelluric (MT) data are being collected in regional grids around the deposits, extending some 200 km north-south and 100 km east-west. MT is a passive electromagnetic geophysical technique that can penetrate beneath cover sequences to provide an image of the electrical resistivity structure of the earth to depths of up to several hundred kilometres. The 3D, lithosphericscale structural information that will result from this dataset will have direct implications for the understanding of lOCGU systems with applications for mineral exploration within South Australia and Australia. Results from currently collected data show that the region towards the eastern margin of the Gawler Craton is significandy more electrically conductive that the centre of the craton. Phase tensor analysis of the MT data shows that the region trends towards electrical one-dimensionality at crustal depths, with increasing two- to threedimensionality and approximately north-south preferential current flow in the upper mande.
ABSTRACTS aiphabeticaiiy by surname of presenting author
Earth's oldest subduction zone? Magnetotelluric and Structural Investigations into the Ubende/Usagaran eclogites, Tanzania K. Selwav^ R. Brick\ A. Collins^ M. Hand\ G. Heinson^ ^ Continental Evolution Research Group, School of Earth and Environmental Sciences, University of Adelaide, SA 5005, Australia. (katherine. selway @ adelaide. edu. au) While subduction-related processes are responsible for much of the tectonism in the modern Earth, the extent to which these processes existed in the Archaean and Palaeoproterozoic Earth is the subject of contentious debate. Eclogites form in high pressure/low temperature (HP/LT) regimes that are characteristic of, but not exclusively limited to, the conditions in the footwalls of subduction zones. The presence of eclogites is therefore a strong indicator for the existence of a palaeo-subduction zone. The oldest confirmed eclogites in the world are in the 2.0 - 1.8 Ga Ubende/Usagaran Orogen in Tanzania, presenting this as a vitally important rock system since it may contain the record of the oldest preserved subduction zone on Earth. A multi-disciplinary project, incorporating metamorphic petrology, structural mapping, geochronology, isotope geochemistry and magnetotellurics (MT) is being undertaken to investigate the tectonic setting and evolution of the Ubende-Usagaran eclogites. MT data have been collected along a 42 km long profile crossing from the Archaean Tanzanian Craton eastwards into the Usagaran Orogen, which contains the Proterozoic eclogites. A lower resistivity feature was modelled that has been interpreted to represent the mid- to lower-crust of the Tanzanian Craton, with a steep easterly-dipping eastern boundary that may represent the truncation of the eastern margin of the Tanzanian Craton at depth. Structural mapping from the Tanzanian Craton through the Usagaran Orogenic belt and into the Pan African Orogenic belt show structures, fabrics and shear sense mosdy consistent with sinistral transpression during oblique convergence. Fabrics generally dip eastwards and the MT data suggest that these easterly dips continue to lowercrustal depths.
The Australian Mineral Occurrence Data Exchange Model. Adele Seymon^ Bruce Simons\ Oliver Raymond^, Lesley Wybom^ ^ GeoScience Victoria, Department of Primary Industries. GPO Box 4440 Melbourne 3001 (adele. seymon@dpi. vic.gov. au; bruce.simons@dpi.vic.gov.au ) ^ Geoscience Australia (oliver.raymond@ga.gov.au; lesley.wyborn@ga.gov.au ) The Australian Mineral Occurrence model is a high-level data exchange standard. It will facilitate data transfer between government, industry and other organisations and can enable a more formal structure for reporting resources and reserves that can comply with national and internationally accepted reporting codes. The mineral occurrences model has been developed under the leadership of the Australian Government Geoscience Information Committee (GGIC). There is currently no easy way to share this data because each State and Territory Geological Survey has its own database, each with its own format and sets of attributes and vocabularies, storing information on mineral occurrences, commodities, historical production, reserves and resources, deposit classification etc. Web services offer a cost efficient technology that permits transfer of selected data, removing both the inconsistencies between datasets, and the need for data to be regularly uploaded to the national database. They offer a chance to access the latest data from the originating agency and return the data in a consistent format. The model is compatible with GeoSciML, the lUGS developed language for exchange of geological map features, and uses patterns and features common to GeoSciML. GeoSciML is based on ISO and Open Geospatial Consortium (OGC) standards using Geographic Mark-up Language (GML) as an encoding for geographic information. Australian Mineral Occurrence Model key points: 1) Describes Earth Resources independent of associated human activities (i.e. mining); 2) Caters for description of Earth Resource using mineral deposit models that describe the actual deposit type; mineral systems that describe the processes associated with deposit formation; and supergene processes; 3) Utilises GeoSciML Mapped Feature to describe spatial representation and Earth Material to describe host and associated materials; 4) Describes a mine as made up of a number of Mining Activities, each producing some commodity; 5) Provides the ability to describe commodity resources formally or informally.
Australian Earth Sciences Convention 2008
225
226 ABSTRACTS alphabeticaily by surname of presenting author
The Meeting of Two Fluids: Mechanisms For Fluid Mixing In The Crust.
^ http://www.bgs.ac.uk/cgi_web/ (cgisecretariat@bgs.ac.uk)
Heather A. Sheldon^ Yanhua Zhang^
The CGI Interoperability Working Group has developed GeoSciML as a geoscience mark-up and interchange language for the information generally shown on geological maps. The UML data model follows the ISO 'General Feature Model' pattern and, in particular, adopts IS019107 for spatial information, which allows for direct implementation as a GML Application Schema. At present, the scope of the model is largely interpreted information, but the intention is to extend it to include more observational data. The incorporation of boreholes using the Open Geospatial Consortium's Observation & Measurement specification is the main current implementation of this. The two types of geological feature modelled are geological units and geological structures. Lithostratigraphic, lithodemic, chronostratigraphic and deformation units are the current specialisations of geological units, but more are planned. Geological structures include shear displacement structures (brittle faults and ductile shears), contacts, folds, foliations, lineations and structures with no preferred orientation (e.g. 'miarolitic cavities'). The earth material package allows for the description of both individual components such as minerals, and compound materials such as rocks or unconsolidated material. Provision is made for weathering, metamorphic, particle geometry, fabric and physical descriptions. Mapped features describe the shape of the geological features using standard GML geometries, such as polygons, lines, points or 3D volumes. Geological events provide the age, process and environment of formation of geological features, and the model accommodates relationships between geological features. GeoSciML incorporates a structure for controlled concepts that can be defined as dictionary terms or as normative descriptions of geological units or earth materials. Each controlled concept has a language independent identifier to allow mapping to various language specific terms. The CGI_Value data type is of particular use in reproducing common patterns for geological properties, as it allows terms, number and range values, all of which may be qualified. A 'geometric description' data type allows recording of linear and planar structural measurements along with a code for the recording convention used (e.g. 'right hand rule') and polarity (e.g. 'overturned').
^ CSIRO Exploration & Mining, PO Box 1180, Bentley, WA 6102, Australia (heather.sheldon@csiro.au) ' CSIRO Exploration & Mining, PO Box 1130, Bentley, WA 6102, Australia (yanhua.zhang@csiro. au) Formation of an ore deposit by fluid mixing requires convergence of fluid pathways from separate sources, followed by mixing on the molecular scale. This contribution examines two ways in which convergence may be achieved, which we describe as fluid ponding and fluid focusing. Fluid ponding occurs when fluids move towards and accumulate at a local minimum of hydraulic head within the crust. This behaviour is driven by dilatant deformation. For example, dilation associated with extensional deformation creates a minimum in hydraulic head at some depth in the crust, which depends on the balance between downward movement of shallow-sourced fluids (e.g. basinal brine, meteoric water) and upward movement of deep-sourced fluids driven by processes such as metamorphic fluid production. Fluid accumulates and remains at this depth until the deformation regime changes. Fluid ponding can also occur during contractional deformation, e.g. at locally dilatant sites along faults, depending on the balance between localised dilation and the regional fluid pressure gradient. Another mechanism of fluid convergence is focusing of fluids into permeable pathways that cross a gradient in hydraulic potential, such as faults or shear zones. For example, magmatic volatiles from an intrusion in the upper crust may be focused into a fault zone that also carries fluid from a deeper source. Unlike fluid ponding, the mixed fluid moves away from the site of convergence. Fluid focusing into permeable pathways may be enhanced by localised dilation (in fact, dilation may be responsible for the increase in permeability); this can occur in both extensional and contractional settings. Fluid focusing is likely to be more effective for mineralisation than fluid ponding because the mixed fluid is removed from the site of convergence and replaced with fresh fluid, thus increasing the amount of fluid that can be mixed in a given volume of rock.
The GeoSciML Logical Data Model of Geological Concepts B. A. Simons ^ CGI Interoperability Working Group^ ^ GeoScience Victoria, Department of Primary Industries, GPO Box 4440 Melbourne, Victoria, 3001. (Bruce. Simons @dpi. vie.gov.au) Australian Earth Sciences Convention 2008
ABSTRACTS alphabetically by surname of presenting author
Quantitative Resource Assessment— A Precursor to Prospectivity Analysis Donald A. Singer^ ^US Geological Survey, Ms901, 345 Middlefield Road, Menlo Park, California, USA 94025 Before decisions are made on where to explore, decisions must be made about what to explore for and whether it is worth the risk. To provide unbiased information, we use three-part resource assessments. This includes: general locations of undiscovered deposits that are delineated from a deposit type's geologic setting; frequency distributions of tonnages and grades of well-explored deposits that serve as models of grades and tonnages of undiscovered deposits; and number of undiscovered deposits that are estimated probabilistically by type. Integrated mineral deposit models are at the core of three-part assessments because they reduce uncertainty about locations, amounts, and values of resources. Grade and tonnage models can provide unbiased representations of grades and tonnages of undiscovered mineral deposits in a permissive tract. Density of deposits (deposits/area) in well-explored control areas can serve to estimate number of deposits. Empirical evidence indicates processes affecting number and quantity of resources in geologic settings are general across many deposit types. Number of mineral deposits is also proportional to the type's size. Total amount of mineralized rock is also proportional to permissive area size and the type's median size. Regressions using these variables provide a means to probabilistically estimate number of deposits and total amounts of mineralization. Despite diverse and complex geologic settings of deposit types, relationships observed indicate universal controls on accumulation and preservation of mineral resources that operate across all scales. Deposit densities can now be used to provide a guideline for expert judgment or used directly for estimating the number of most kinds of mineral deposits. To consistently assess undiscovered mineral resources, areas are delineated where geology permits existence of deposits of one or more specified types. After deciding to explore a tract for a deposit type, tools such as probabilistic neural networks, logistic regression, or weights-of-evidence can be used to identify specific targets.
Relationships Between Magnetite Trace Element Compositions and Mineral Paragenesis Blackwell Singoyi^ Garry Davidson^ Khin Zaw^, Ross Large ^ ^ CODES ARC Centre of Excellence in Ore Deposits, University of Tasmania, Private Bag 79, Hobart, Tasmania 7001, (bsingoyi@utas.edu.au) A wide range of elements including Mg, Al, Ti, V, Mn, Fe, Co , Zn, Ga, Y, Zr, Nb, Mo, Sn, Eu, W, Au, Pb, and U were analysed in magnetite grains from several hydrothermal deposits in Australia (e.g. Kara Fe-W skarn, Sylvester Pb-Zn-Ag skarn and Mt. Lyell Cu-Au volcanic-hosted massive sulphide deposit in Tasmania and the Cannington Ag-Pb-Zn Broken Hill Type deposit in Queensland) using the laser ablation inductively coupled plasma mass spectrometry (LA ICP-MS) technique at CODES, University of Tasmania to determine the significance of compositional variations between magnetites from different mineral paragenetic stages. Magnetites from different spatial-temporal mineral paragenetic stages appear to show some systematic compositional variations. At Kara and Sylvester, magnetites associated wit h early prograde mineral assemblages proximal to the fluid sources (Housetop and Heemskirk Granites, faults) generally contain a wider range of trace elements (e.g. Ti, V, Co, Ni, Zn, Ga, Zr, Nb, Sn) in higher concentrations than magnetites in distal or later mineral assemblages. At Mt. Lyell, early anhedral magnetites associated with pyroxene-plagioclase also have wider trace element compositions in higher concentrations than euhedral or aggregate magnetites in later veins or replacement mineral assemblages containing chlorite and the major chalcopyrite mineralisation. At the Cannington deposit, the same trend is repeated. This investigation appears to show that elements such as Ti, V, Co, Ni , Mn, Zn, Ga, Sn are incorporated into magnetite in high concentrations during the early stages of deposit formation and less so during the later stages of deposit formation. This observation may be attributed to physical-chemical changes during deposit formation. These systematic magnetite compositional variations may prove a useful exploration tool.
Australian Earth Sciences Convention 2008
227
228 ABSTRACTS alphabetically by surname of presenting author
Field Portable XRF for geological in-situ sampling: calibration and refinement of instrumental precision and accuracy for field measurements K. Sircombe^ D. Jorgensen\ N. Coleman^ E. Webber^ ^ Geoscience Australia, GPO Box 378, Canberra A CT 2601 (Keith. Sircombe @ ga. gov.au) Field portable X-ray fluorescence (FPXRF) complements conventional geological sampling and laboratory analysis via in situ analysis at the rock outcrop. While FPXRF is capable of accurate and precise measurement of silicate rock samples prepared and analysed as powder pellets, limitations can arise when considering the use of this instrumentation upon rock surfaces in the field. A series of laboratory and field experiments were conducted to test and refine instrument precision and accuracy and also field analytical procedures to ensure representative sampling. Tests included recalibration of factory settings against known reference materials, exploring potential correlations between x-ray response and rock composition (mafic/felsic), x-ray response and sample temperature and x-ray attenuation due to air gap between detector and sample. Because of obvious instrument size constraints on beam strength, limits of detection and quantitation are always going to restrict the application of the FPXRF to certain elements that typically occur in higher concentrations (for instance Zr in felsic country rocks or Pb-hZn in mineralised strata). Analysed rock surfaces need to be as flat and clean as possible, and the number of repeat measurements required for statistical adequacy varies from 2 to 5 depending on the rock grain size. Despite these limitations, the capability to undertake a preliminary assessment of results during a field survey and to modify the sampling and analysis programme interactively is the greatest attraction to geologists.
A Prototype Information Model and Markup Language For Geochemical And Geochronological Information. K.N. Sircombe^ N. Ardlie\ L. Sullivan\ T. Memagh\ L. Wybom\
^ Geoscience Australia, GPO Box 378, Canberra ACT2601 (Contact: Keith.Sircombe@ga.gov.au) The ability to integrate data from multiple sources and subsequently synthesise geological interpretations is a critical aspect of modem geological research and resource exploration. However, such research remains limited because of the burden of integrating disparate data. Although Australian Earth Sciences Convention 2008
there are several 'on-line' resources for accessing geochemical and geochronological data, there is no standard format for exchanging these data among users. Current exchange formats include commadelimited text files, spreadsheets and PDFs. These formats lack schematic or semantic maturity, assume prior specialist knowledge, are poorly documented, and are often platform dependent. The incorporated data typically require manual processing, which is both costly and error-prone. These problems can be eliminated by interoperability of data exchange based on canonical XML (extensible Markup Language) information models. Geoscience Australia and its partners are using this methodology to develop a standard exchange format for geochemical and geochronological data. This format leverages internationally recognised information models, open standards and related schema such as Chemical Markup Language, Geography Markup Language, Geoscience Markup Language, Observations and Measurements and Sensor Markup Language. The use of these standards ensures that shared features (such as sample location, time of analysis or instrument settings) are described in a consistent manner and maximises the broader relevance and applicability of the model. The prototype model largely focuses on the exchange of 'published' data, and in an attempt to avoid method-specific design it includes: - A core description of analytical values and uncertainties based on molecular measurements and ratios. - A 'Specimen container' description separate from analyses. - Interpretation' descriptions separate from analyses to enable linking of multiple interpretations to single data sets. This presentation will discuss developments at Geoscience Australia and the opportunities for collaboration.
Uranium Mineralising Systems: A Continuum of Deposit Styles? Roger G. Skirrow^ Subhash Jaireth\ David L. Huston^ Andrew J. Barnicoat\
^ Geoscience Australia, GPO Box 378, Canberra, A CT 2601 (roger. skirrow @ ga. gov. au) Most current classification schemes for uranium deposits emphasise differences in host rock type, resulting in a plethora of apparently separate deposit styles. While this scheme has been useful in categorising uranium resource data, it has limitations when assessing greenfields regions for undiscovered or unrecognised styles of uranium deposits. We propose an alternative scheme that describes a continuum of possible deposit styles. It is based on the fundamental properties of uranium and its physico-chemical behaviour during earth processes. Three end-member fluid types are typically responsible for the transport and deposition of U ^
ABSTRACTS alphabetically by surname of presenting author
and magmatic-hydrothermal, 'metamorphic' (including fluids reacted extensively with metamorphic rocks), and hydrosphere-derived. The endmember fluids are principal components in three uranium mineralising systems: magmatic-, metamorphic-, and sedimentary basin-related. Each system contains a range of deposit styles, reflecting the continuum in properties between end-member fluid types as well as differing geological settings. Magmatic-related uranium systems encompass a range of deposit styles from 'orthomagmatic' to hybrid styles dominated by magmatic-hydrothermal fluids but with contributions of hydrosphere-derived or metamorphic fluids. Uraniumrich iron oxide Cu-Au deposits form by the action of hydrosphere-derived fluids either mixing with hybrid magmatic-metamorphic fluids or overprinting the oxides and sulfides. 'Metasomatic' deposits probably derive from a range of magmatichydrothermal to metamorphic fluids. Sedimentary basin-related uranium systems contain a suite of deposit styles that share several fundamental characteristics and processes. One endmember fluid is oxidised water from the hydrosphere. Reaction with basin and/or basement rocks with leachable uranium may result in U-rich groundwaters, formation waters and connate brines. End-member metamorphic (including diagenetic) fluids may mix with these waters. Uranium is deposited via fluid-rock or fluid-fluid reactions predominantly involving reduction or evaporation. We support the growing recognition that 'sandstonehosted', 'unconformity-related' and 'Westmoreland' type deposits are members of a continuum of styles within basin-related systems. Hybrid deposit styles are a predicted consequence of the proposed scheme.
Were There Two Or Three Proterozoic Supercontinents? Quantitative Tests of Craton Connections In Geon 24. Smimov,
W.B.^
Evans, D.A.D.^ Rathbun,
^ Michigan Technological University, Houghton, MI, 49931, USA (asmirnov@mtu.edu) ^ Dep't. of Geology & Geophysics, Yale University, New Haven CT 06520-8109, USA (dai. evans@yale. edu) Although a supercontinent cycle is suggested by persistent global peaks in isotopic ages that could reflect periods of continental assembly at ca. 27002600 Ma (Geon 26, forming Kenorland), 1900-1800 Ma (Geon 18, forming Nuna a.k.a. Columbia), and 1100-1000 Ma (Geon 10, forming Rodinia), none of these proposed supercontinents have been reconstructed with confidence. Even the existence of Kenorland is in doubt, as the geologic record can be interpreted instead in terms of several paleogeographically distinct supercratons. One of these, "Superia" (including Superior, Kola, Karelia, Heame, Wyoming, and perhaps Nain and Yilgam) is
linked via ca. 2700 Ma cratonization followed by extensive 2500-2100 Ma dyke swarms. We report high-quality paleomagnetic data from the Widgiemooltha dyke swarm, which strikes east-west across the Yilgam craton. Our samples represent 22 sites from 15 dykes, including the Binneringie dyke that extends >500 km subparallel to a paleomeridian. The data imply a moderate-high paleolatitude for Yilgam at 2415 Ma, which contrasts the lower-paleolatitude results from nearly coeval mafic rocks on Superior and Karelia. Our data appear to exclude Yilgam from the immediate vicinity of Superia. However these paleolatitudes may be biased if the Paleoproterozoic field contained significant non-dipolar components. The large extent of the Widgiemooltha dykes allows a test of the dipole assumption by comparing the observed paleodirections with those predicted by a dipolar field model. Although this test is still inconclusive, our project is continuing with more sample collection and analyses. We also report preliminary Thellier paleointensity results from Widgiemooltha dykes, providing insight into the field geometry and perhaps also the timing of inner core nucleation. We expect that the next decade of globally active geochronologic/paleomagnetic research on Paleoproterozoic dykes will determine whether a supercontinent existed before 2 Ga, and thus whether a supercontinental cycle can be constmcted through the entire latter half of Earth history.
Technology Advances; Neutron Activation Borehole Logging for Measurement of Elemental Abundance, Mineralogy, Lithology, Porosity and Hydraulic Conductivity Craig Smith\ Chris Waring^ ^ CSIRO Exploration and Mining, Technology Crt, Pullenvale QLD, Australia 4069 (Craig. Smith @ csiro. au) ^ ANSTO Institute for Environmental Research, PMB #7, Menai NSW 2234, Australia. (clw @ ansto. gov. au) Prompt gamma neutron activation borehole logging technology has been developed by CSIRO and used in the mining industry for 15 years. PON A logging has been apphed to diverse applications, such as ash content of coal, Ee & Cu grade, and S content of gangue. ANSTO has appUed PGNA logging to hydrology, developing a method of measuring hydraulic conductivity at 20cm increments along boreholes. New LaBrsCe detectors have recendy become commercially available in a size range suitable for efficient borehole logging (50 x 100mm). Improved spectral resolution offered by LaBrsCe detectors allows measurement of elements previously not able to be resolved (eg. Ti, U series daughters, +) and significantly improved
continued next page..
Australian Earth Sciences Convention 2008
229
230 ABSTRACTS aiphabeticaify by surname of presenting author
quantification limits for H, Si, CI, Fe, & S. New software for gamma spectral analysis has also improved elemental quantification. These advances in technology now allow direct grade measurements for a larger range of elements. Most rock forming elements can be detected by the new PGNA logging system and combining these allows inference for most common minerals. Other useful parameters such as lithology and porosity can also be calculated. Measurement of hydraulic conductivity requires injection of a tracer solution (NaCl) and measurement of the variable distance the tracer has moved by PGNA geophysical logging. Subde variations in lithology not apparent by visual inspection such as degree of cementation or clay pore filling in sandstone may also be detected. Porosity and lithology estimation by PGNA logging does not require a tracer solution to be injected and may be measured through borehole casing with screened or unscreened intervals.
Lake Muir-Unicup Natural Diversity Recovery Catchment — Groundwater Chloride/Bromide Ratios Margaret G. Smith\David J. Gray^ ^ CRC LEME/Environmental Inorganic Geochemistry Group, Curtin University of Technology, Bentley GPO Box U 1987, Perth WA 6845 (margaret.smith@csiro.au) ^ CRC LEME/Exploration and Mining CSIRO PO Box 1130 Bentley WA 6102 (david.gray@csiro.au) The Lake Muir-Unicup Natural Diversity Recovery Catchment has groundwater ClVBf mass ratios ranging from 280 to 1070 (compared to 292 for seawater) suggesting Br" depletion even in areas where Br' enrichment would be expected. The catchment covers an area of 700 km^ and is located about 300 km south of Perth. Annual evaporation of 12 000 mm exceeds the average annual rainfall of 700 mm. This internally draining catchment has at least two hydrofacies: 1) The Na-Cl type waters are found in the north of the catchment and under Lake Muir. The TDS ranges from 1000 to 30 000 mg/L (in the north), and between 34 000 and 77 000 mg/L at 1 m depth below Lake Muir (in the south) and are typical of groundwater in the wheat belt of Western Australia. 2) The Ca-Na-Cl type waters are found in the south of the catchment, to the east of Lake Muir. The TDS is between 20 000 and 50 000 mg/L. Groundwater CI" and Br" in the south west of Australia are mainly marine and are deposited from rainfall. Anthropogenic sources (CI", fertiliser; Br", pesticides) are considered negligible for this forested catchment. Therefore, an initial seawater CI/Br" ratio of 292 is assumed. In water CI" and Br" are conservative ions until halite saturation occurs. The Australian Earth Sciences Convention 2008
Br" is excluded from the halite crystal and the residual brine becomes enriched in Br". Bromide appears to be depleted throughout the catchment even in areas where Br" enrichment is expected, such as groundwater discharge sites. At these sites, halite forms on surface as the groundwater evaporates. Removal of this halite by wind or the first winter rains should results in Br" enrichment not depletion as currently seen. Could plants be the explanation for the depletion? Plants are known to utilise Br". Recent study looked at emission rates of methyl halides (CH3CI, CHsBr) from tropical ferms and have found that the emission ratio of CK^Cl/CH^Br is about 120 and 30 for Cyathea podophylla and C. Lepifera respectively (Saito and Yokouchi, 2006). If native Australian plants have similar emission ratios then the Br" will be utilised before reaching the groundwater.
Sequence Stratigraphy and Seismic Facies of the Eucla Basin, Great Australian Bight, South Australia Sian Smith \ Dietmar Muller^ Peter Co well ^ and Jennifer Totterdell^
^Earthbyte Group, School of Geosciences, University of Sydney, Australia, NSW 2006 ^Geoscience Australia, GPO Box 378, Canberra, ACT, 2601 The Eucla Basin is the largest Cenozoic basin on Australia's southern, passive continental margin, which developed by the extension and rifting between Antarctica and Australia. A recent collection of high-resolution seismic reflection data and the combination of core data from ODP Leg 182 drill sites presents an opportunity to improve our understanding of the margin's response to local and global processes. These include paleoceanography, regional tectonics and carbonate deposition in a mid- and high-latitude setting against the background of an evolving Southern Ocean and northward drift of the Australian continent. The Eucla Basin is divided into seven seismic sequences that reflect four major depositional phases. The basal sequence of Paleocene to Early Eocene age, unconformably overlies the Cretaceous succession of the Eucla Basin. It comprises of a sequence of shallow-water terrigenous sands and carbonates, with extensive incisions and canyons at the basal sequence boundary. Mid-Eocene to Pleistocene sequences (~1 km thick) are dominated by a monotonous cool-water carbonate succession with numerous incisions, progradational units and biogenic mounds. The deposition of cool-water carbonates coincides with accelerated sea-floor spreading and an increase in the vigour of the Antarctic Circumpolar Current. This initiated widespread in
ABSTRACTS alphabetically by surname of presenting author
margin has been essentially tectonically stable, but was affected by vertical motions driven by mantle convection. The resulting regional tectonic tilting (<lkm) in the Miocene caused exposure of the Nullarbor Plain, hmiting Neogene sedimentation to the modern day outer-shelf and upper-slope. The continental shelf edge has migrated seaward, forming spectacular cool-water carbonate ramp geometries with numerous and extensive biogenic mounds. Periods of margin instability, seismicity, or lowered sea level are characterised by slumps, sediment gravity-flow deposits, and/or unconformities.
The Neves Corvo (Portugal) massive sulphide deposit: depositional instability in the Lombador lens, and the origin of the sulphur Mike Solomon^Carlos Inverno^, Nelson Pacheco^, Paulo C. Noiva^ Gongalo Barriga^, Alfredo Ferreira"^, Orlando C. Caspar^ ^ CODES, University of Tasmania, GPO Private Bag 79, Hobart, Tasmania 7001, Australia ^INETI - Servigos Geoldgicos, Estrada PortelaZambujal, Apartado 7586, 2720-866 Alfragide, Portugal; CREMINER, Universidade de Lisboa, Edificio C6, 1749-016 Eisboa, Portugal ^ SOMINCOR, Mina de Neves-Corvo, 7780 Castro Verde, Portugal ^ Rua Jose Ary dos Santos, 1, 7780 Castro Verde, Portugal ^ Rua Marechal Saldanha, 935-2''Dto., 4150-659 Porto, Portugal The Lombador massive sulphide deposit, one of five comprising the Neves Corvo deposit, Hes north of the Sn-Cu-rich Corvo and Graga lenses. Six drill-hole intersections show that it is stratiform and dominantly finely grained pyrite plus sphalerite, galena and chalcopyrite, with up to 0.3 wt.% Sn; it is underlain by barren, Cu-rich and Zn-rich stock works. Framboidal and colloform textures abound, suggesting that it represents the quenched product of sea-floor venting hydrothermal fluids. While the lower parts are dominantly massive the upper parts are commonly fragmental and bedded (with graded bedding and load casts), and include units of siliceous grey shale, the main host rock. Fragments show delicate textures and poor sorting, suggesting minimal transport. The textures and shale beds point to intermittent mineralization repeatedly interrupted by minor tectonic(?) disturbances. Metal grades within the massive ore show no systematic variation with respect to stratigraphy or texture. d^'^S values range from -14.2 to 4.8 %c
(n=61). Most of the negative values occur in the top 0 to 9 m with values increasingly negative upward; below, they average 1.3 %c in massive ore and 1.6 %c including stockworks. The negative trend in the upper parts suggests a component produced by biogenic reduction of seawater sulphate, the proportion apparently increasing with time, perhaps related to a declining sulphur content in the ore-forming fluids. The main sulphide sulphur has a signature close to that seen in Sn-W deposits, for example, in the Mole granite (-4 to 3.5 %o), the Aberfoyle Sn-W veins (-3.3 to 3.6) and the Mount Bischoff Sn deposits (-0.7 to 3.8), all closely related to granites. The metal content of Neves Corvo in toto is not unlike that of deposits like Renison and Mount Bischoff except for low Zn/Pb which is also low compared to other pyrite belt ores.
Geoscience Australia, Offshore Energy Security Program: an Update of Planned Marine Surveys and Initial Results. Peter Southgate , Clinton Foster , Edward Bowen', Marita Bradshaw^ Barry Bradshaw 1, Robert Langford ^ — ^ Jennie Totterdeir ^Geoscience Australia GPO Box 378 Canberra ACT 2601 (peter, southgate @ ga. gov. au) The Australian Government's Offshore Energy Security initiative will provide precompetitive data and information to stimulate petroleum exploration in Australia. The program will focus its efforts in three frontier regions: 1) the Southwest margin, including the Mentelle, north Perth (Houtman and Zeewyck basins) and southern Carnarvon basin; 2) the Southern margin including the Bight and Sorell basins and 3) the Remote Eastern Frontiers region, offshore eastern Australia. Three styles of marine survey are planned. Reconnaissance marine surveys will collect gravity, magnetics, multibeam swath and sub-bottom profiler geophysical data. An accompanying seafloor sampling program will acquire geological and biological samples from potential seepage sites and representative areas of the sea floor, to search for indications of active petroleum systems and to document marine biodiversity and habitats. These datasets will inform marine planning and environmental policy decisions. A marine reconnaissance survey in the Capel and Faust basins of the Remote Eastern Frontiers region was undertaken in October/November 2007 using the RV Tangaroa. Subsequent marine reconnaissance surveys are scheduled for the period November 2008 to March 2009 and will include acquisition in the Houtman and Zeewyck basins of the southwest margin and possibly the Bight and Sorell basins of the southern margin. continued next page.. Australian Earth Sciences Convention 2008
231
232 ABSTRACTS alphabetically by surname of presenting author
2D seismic acquisition surveys will use industry standard, 6-8 km length solid steamers with the objective of imaging the crust to depths of 12 seconds TWT. Subject to vessel availabihty a 2D seismic survey is scheduled for late 2008 to early 2009 for acquisition in the Mentelle, Abrolhos, Houtman and Zeewyck basins of the SW Margin. Prospectivity assessment surveys will involve the collection of sea floor samples to ground-truth seismic interpretations, including the key petroleum system element of source and potential sites of hydrocarbon seepage and fluid flow identified from seismic and multibeam/sub-bottom profile data interpretations. These surveys will be undertaken in the later stages of the program.
Using Time-Constrained Faeies Belts & Sequence Models to Correlate the Western and Eastern Successions of the Mt Isa Inlier: Implications for Fluid Migration P.N. Southgate\ G.M. Gibson\ N.L. Neumann\ L. Hutton^ ^Onshore Energy and Minerals Division, Geoscience Australia, PO Box 378, Canberra, ACT 2601 (peter, southgate @ ga. gov. au) ^Geological Survey of Queensland, Indooroopilly, QLD 4068 In the Mt Isa Inlier the lack of detailed facies models and insufficient age information have inhibited regional correlations. To understand if rocks of the Eastern and Western Successions comprise a single depositional system or several accreted terrains it is necessary to understand the evolution of time-equivalent depositional systems and test the proposed correlations using SHRIMP geochronology. Sedimentary rocks of the Western Succession comprise two depositional systems each composed of six siliciclastic and six carbonate facies. These systems developed in response to storm-dominated sediment transport and dispersal mechanisms on a platform. Siliciclastic facies developed on the landward portions of the platform; carbonate facies accumulated further offshore. Most of the facies in the Eastern Succession correspond to those of the Western Succession and accumulated on a platform, with deeper water facies more common in the east. In marked contrast, tubidites of the Soldiers Cap Group and Kuridala Formation accumulated in significandy deeper water, basinal facies, lacking counterpart rocks in the west. Turbidite sediments of the Soldiers Cap Group and Kuridala Formation accumulated as supersequence lowstand deposits, basinward of a platform margin. Deposition occurred when the platform was subaerially exposed, leading to erosion and the development of a break-up unconformity. Australian Earth Sciences Convention 2008
the Gun Supersequence boundary. Siliciclastic and carbonate facies belts accumulated in transgressive and highstand systems on the platform as rift-related extensional processes were replaced by thermal sag. Based on this geometric analysis, the Mt Isa Pb-Zn-Ag deposits are restricted to supersequence transgressive and highstand deposits of the platform and contrast with the basinal supersequence lowstand, sediments that host the Broken Hill type deposits. Palaeogeographic models developed from improved correlations between the Western and Eastern successions require a geometric separation of fluids associated with these styles of deposits.
The C. 1680 Ma Dalyup Gneiss of The Albany-Fraser Orogen, Western Austraha: What is it, and Where Did it Come From?
Catherine V. Spaggiari\ Simon Bodorkos^, Ian M. Tyler\ Miriam Barquero-Molina^ ^ Geological Survey of Western Australia, 100 Plain Street, East Perth, WA, 6004, Australia (catherine.spaggiari@doir.wa.gov.au) ^ Geoscience Australia, GPO Box 378, Canberra ACT2601, Australia ^ Department of Geological Sciences, The University of Texas at Austin, 1 University Station CI 100, Austin, TX 78712-0254, USA The Albany-Fraser Orogeny is widely accepted as representing the 1345-1260 Ma collision of the West Australian (Yilgam) and Mawson Cratons (Stage I), followed by 1215-1140 Ma intracontinental reworking (Stage II; (Clark et al., 2000, Precam. Res. 102, p. 155-183). Within the orogen, the tectonic affinities of the granitedominated Munglinup and Dalyup Gneisses have long been uncertain; however new geochronological data and geophysical interpretation show that the two are separate lithotectonic units. Late Archean ages have been confirmed for protoliths of the Munglinup Gneiss, which represents the reworked Yilgam margin. In contrast, the Dalyup Gneiss is an exotic, c. 1680 Ma, -25 by -800 km mid-crustal belt that wraps around the southern and southeastern craton margin, with no Yilgam affinities. Both are intmded by c. 1300 Ma granitic rocks, and in the absence any c. 1680 Ma event affecting the southem Yilgam, suturing of the Dalyup Gneiss to the craton margin is interpreted to have taken place during Stage 1 of the orogeny. This suggests that the Dalyup Gneiss was accreted either to the southem Yilgam margin during the early stages of Yilgam-Mawson convergence, or to the northwestem Mawson Craton margin (Nomalup Complex) prior to collision. The origin of the Dalyup Gneiss is unknown, but possible correlatives occur within the northwestem Gawler Craton, which contains various granitic and arc-like rocks of similar age (e.g. Ifould and Tunkillia Suites), formed during the early stages of the Kararan Orogeny. Geochemical data for the Dalyup Gneiss are limited but Sm-Nd data indicate a cmstal source (Nelson et al, 1995, Aust. J. Earth
ABSTRACTS alphabetically by surname of presenting author
Sci., 42, p. 481-495). The Dalyup Gneiss may represent a continental ribbon rifted off during subduction retreat along a major, long-lived northdipping subduction zone that extended across a broad part of central Australia (e.g. Betts and Giles, 2006, Precam. Res. 144, p. 92-125).
Architecture of Archean Greenstones at St Ives: A Vector to Au and Ni Ore Squire, RJ. , Stolz, E.^ Cas, R.A.R^ Champion, D.C?, Halley, S.^ Tunjic, J.^ School of Geosciences, Monash University, VIC, 3800 (Rick. Squire @ sci. monash. edu. au; Ray. Cas @ sci. monash. edu. au) Geoscience Australia, Canberra, ACT, 2609 (Ned. Stolz @ ga. gov. au; David.Champion@ ga.gov.au) ^Mineral Mapping, Perth WA (minmap @ westnet. com.au) ^ Goldfields Australia (Stives Gold Mine), WA, 6442 (Janet. Tunjic @ goldfields. com. au) The structural and stratigraphic architecture of Archean greenstone successions is widely recognised as a crucial control on the distribution of world-class gold and nickel deposits in the Yilgarn Craton. Unfortunately, the paucity of surface outcrops and a heavy reliance on data from singlediscipline (e.g., regional geophysical surveys) and/or deposit-scale investigations have resulted in a relatively poor understanding of the camp-scale architecture of these important terranes. However, we will show that substantial and rapid improvements can be made to our understanding of the camp-scale architecture by assessing the temporal and spatial distribution of the region's principal volcanic and intrusive units. In the St Ives district, located near Kambalda in Western Australia, we used differences in the characteristics of the greenstone units, felsic volcaniclastic successions (i.e.. Black Flag Group) and late (porphyritic) intrusions to identify several previously unrecognised northwest-trending fault-bounded domains. The most important outcome of this investigation was that all the major gold deposits in the region are located near the margins of these newly identified domains. In addition, different types of gold deposits appear to be confined to particular domains: the + IMoz deposits at Junction and Argo are restricted to one domain, and porphyry-style deposits such as Bellerophon to a particular package of the Black Flag Group in another domain. Differences in the geochemical, geophysical and/or textural characteristics of the greenstone units in the different domains were also identified, indicating important and long-lived controls on the region's tectono-magmatic evolution. These controls, we believe, were also important during genesis of the region's world-class nickelsulfide deposits.
Coastal Geographic Information System (GIS) for the Northern Agricultural Region (NAR) of the Western Australian Coast Alexandra Stevens ^ Lindsay Collins ^ Brad Rushforth^ ^ M.A.Stevens@curtin.edu.au This project aims to design and build a Geographic Information System (GIS) for the Northern Agricultural Region (NAR) Coast. The project focuses on the coastal zone of the NAR of Western Australia extending from Guilderton to Kalbarri. 'The coast in the NAR is defined as the narrow strip of mainly sandy deposits of Holocene age along the coast, varying in width between 1 and 10 km, with most areas being about 5 km' (NACC 2005). The GIS layers will cover between 2.5 and 10 kms depending on the nature of the layer. The project aims to assess and address threats to the coastal strip through the creation of a coastal GIS with multiple user groups in mind and to deliver a GIS product and Metadata set that will be an invaluable tool for coastal planners and managers. The GIS will be essential for identifying the present status of our coastline and will provide a valuable monitoring tool for environmental change and for future coastal planning at strategic, local and site levels. An appropriate combination of layers will identify areas susceptible to future change or at greatest risk. The results of this process will enable the implementation of management strategies in a more cost effective manner. The GIS provides a dynamic database, with data presented in mapped form, of the coastal zone that will also allow for documentation of onground works and coastal remediation. Initial stages of implementation of coastal management goals have commenced based on the data provided by the GIS.
A Gawler Orocline? YarlbrindaOolabinnia Shear Zone Connections. John R. Stewart^ Peter G. Betts ^ ^ School of Geosciences, Monash University, Clayton VIC 3800, Australia (John. Stewart @ sci. monash. edu. au) Analysis of potential field datasets over the central Gawler Craton show that the Yarlbrinda and the Oolabinnia Shear Zones, previously treated as separate structures, are in fact one single, continuous structure. This connection is previously unrecognized possibly because it is folded, offset and overprinted during subsequent tectonic episodes. The ~N-S trending Yarlbrinda Shear Zone is interpreted to have been truncated by dextral movement along the E-W trending Yerda Shear Zone to its north. However, the sense of drag of the
continued next page..
Australian Earth Sciences Convention 2008
233
234 ABSTRACTS
alptiabetlGaliy by surname of presenting author Yarlbrinda Shear Zone into the Yerda Shear Zone is opposite to that expected by well-constrained kinematic indicators from within the Yerda Shear Zone. The structural grain of the Yarlbrinda Shear Zone does not intersect with the Yerda Shear Zone, rather it is folded through -90"" to continue in an ~EW direction as the Oolabinnia Shear Zone. The Oolabinnia Shear Zone has not undergone detailed analysis and has not been placed into a regional tectonic context. Moreover, previous interpretations show it terminating against the ~NESW trending Koonibba Fault, just west of the Yarlbrinda Shear Zone. Folding of the Yarlbrinda-Oolabinnia Shear Zone can be constrained by several regional tectonic events: 1) Emplacement of ca. 1680 Ma Tunkillia Suite plutons within the Yarlbrinda-Oolabinnia Shear Zone; 2) Folding of the shear zone; 3) the folded shear zone is offset by the ~NE-SW Koonibba Fault system which deforms ca. 1620 Ma St Peters Suite rocks but ceased activity during the ca. 1595-1575 Ma Hiltaba Event; 4) YarlbrindaOolabinnia Shear Zone is overprinted by Hiltaba Suite plutons and mylonites of the Yarlbrinda Shear Zone are underlying/in contact with undeformed ca. 1592 Ma Upper Gawler Range Volcanics. These observations provide a time frame in which to place terrane-scale folding that has produced the oroclinal geometry of the Gawler Craton. This oroclinal folding may also be related to tight folding of the Karari and Tallacootra Shear Zones in the Western Gawler Craton. The continuation of the Oolabinnia Shear Zone and the Yalbrinda Shear Zone may have some exploration implications because the Yalbrinda Shear Zone is host to several significant zones of gold mineralization.
The --3.43Ga Strelley Pool sandstone as an environment for early life.
David Wacey, Cris Stoakes^, Matt Kilburn^ ^Department of Earth Sciences, University of Oxford, Parks Road, Oxford 0X1 3PR, UK. Email: davidwa&,earth, ox. ac. lik ^C.A Stoakes and Associates Pty Ltd, 3185 Victoria Road, Hovea, W.A. 6071, Australia Email stoakescaimoptusnet. com., an ^Centre for Microscopy, Characterisation and Analysis, University of Western Australia, Stirling Highway Crawley, W.A. 6009, Australia. Email: matt.kilburn(a),uwa. edu. cm Ancient sedimentary environments are considered to be the most likely to contain evidence of early microbial and extremophile life. Low metamorphic grade together with good exposure and preservation makes the basal sandstone of the Strelley Pool Formation a Australian Earth Sciences Convention 2008
favourable place to search for traces of early organisms. Detailed mapping and sampling of a 12 kilometre section determined that the sandstone was likely deposited as a placer in shallow water. Local darker zones within the sandstone were found to contain numerous clasts of crypto-crystalline silica associated with significant quantities of pyrite and carbon. Microscopic analysis of the lithic grains from these darker sandstones identified numerous microtubular structures which can be shown to be of either syngenetic or diagenetic age. To date, none of these structures have met the criteria as endolithic borings similar to those identified in the overlying Eurobasalt. However, some of the microstructures proved to have a strong similarity to Ambient Inclusion Trails (AIT) as recognized in younger rocks. These enigmatic microtubes are considered to be the result of mineral crystals migrating through a liquefied substrate, the possible driving force being gases generated by the decomposition of organic material. AIT structures were identified from the centre of sandstone grains where they have been sealed from later fluid flow preserving the primary Archean biological signature. NanoSims technology has demonstrated a unique opportunity to combine sub-micron scale imaging with in-situ chemical analysis. Enrichment of key elements and isotopic fractionation can be powerful tools to identify the presence of distinctive bio-signatures. As early organisms are unlikely to directly concentrated on finding secondary traces of their metabolic processes. In order to sustain a claim for early life, abiotic processes need to be thoroughly excluded.
Titanite as a Tracer of Crustal Evolution
Craig StoreY\ Chris Hawkesworth\ John Craven^ ^ Dept. of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol, BS8 IRJ, UK (c.storey@bristolac.uk) ^ NERC Edinburgh Ion Microprobe Facility, School of Geosciences, Grant Institute (Earth Sciences), University of Edinburgh, Kings Buildings, West Mains Road, Edinburgh, EH9 3JW, UK Titanite (CaTiSiOs) is a common mineral in a variety of rock-types and is an important repository of a variety of trace and rare earth elements, U and Th. It has been utilised fairly widely for U-Pb dating of igneous events, metamorphic reactions and hydrothermal activity. Its success is largely due to its common presence, relative large size, robustness and easier to interpret reaction history compared to zircon. In contrast, the closure temperature for Pb is rather lower than that of zircon at c.650T (>900T
ABSTRACTS alphabeticafty by surname of presenting author
for zircon). As such, it is often viewed as a mineral appropriate for recording the cooUng history of magmatic rocks or metamorphic terranes. However, there are well documented cases of titanite recording the same, or very close to the same ages as zircon even in Archaean terranes. Furthermore, unlike zircon where the emphasis over the last 20 years has been towards in-situ measurements to date both cores and overgrowths, little such work has been done on titanite. A few recent studies have shown that such an approach for titanite may be both valid (Storey et al, 2006) and insightful (Storey et al, 2007). In the study of Storey et al (2007) it was shown that titanite retained core ages and mineral chemistry distinct and older than the rims and, as such, this may be more common than generally considered and offers hope for titanite as a long-term recorder of crustal processes. This could be of particular utility since titanite begins to crystallise in less evolved (diorites), generally I-type melts and may therefore record a more thorough history of the evolution of a craton, particularly since bulk crust is andesitic in composition. In this study we present in-situ U-Pb, O and Nd data on titanite and discuss how the data complement similar studies on zircon.
Highly elaborate putative microfossils from >2.97 Ga chert, Pilbara Craton: indications of cell division? K ^ ^ u g i t a n i ^ K. Gre>^' ^ T. N a g a o k a ^ K. M i m u r a \ M.R. Walter^ ^ Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan (sugi@info. human, nagoya-u.ac.jp) Geological Survey of Western Australia, Department of Industry and Resources, 100 Plain Street, East Perth, WA6004, Australia (kath.grey@doir. wa.gov. au) ^ Australian Centre for Astrobiology, Macquarie University, Sydney, NSW2109, Australia School of Informatics and Sciences, Nagoya University, Nagoya 464-8601, Japan A diverse assemblage of probable microfossils is present in the sedimentary succession at Mount Grant and Mount Goldsworthy, Pilbara Craton, now assigned to the >2.97Ga Farrel Quartzite (Gorge Creek Group) (Sugitani et al., 2007, Precambrian Research, v. 158, p. 228-262). Four major morphological types have been identified: thread-like, film-like, spheroidal and lenticular to spindle-like. Biogenicity of most of the microstructures is inferred from indigenousness, syngenicity, the sedimentary origin of the host chert, narrow size distribution, composition, evidence of flexible and/or breakable walls, taphonomic features and the presence of colony-like aggregations.
In addition to the major morphological types, highly elaborate, complex morphologies were found. They include 1) coupled spheroids, 2) chain-like arrangements of lenticular structures, 3) oblique arrangement of lenticular structures, and 4) large spheroids containing internal objects. These "composite" morphologies are suggestive of colonial and reproductive styles observed in modern microorganisms. If some of the Farrel Quartzite microstructures represent reproducing cells, this coupled with the unusually large size for prokaryotic microorganisms (up to 30 jum or more), would have important implications for evolution. Based on the examination of ca. 2000 specimens, we infer that some Farrel Quartzite microstructures could represent reproductive stmctures, providing a framework on which to base future taxonomic and phylogenetic studies.
Ngukurr Groundwater Investigation, Northern Territory, Australia Jonathan Sumner^ ^ Water Resources Branch, Department of Natural Resources, Environment and the Arts, Goyder Building, Chung Wah Terrace, Palmerston, Northern Territory, Australia (jon.sumner@nt.gov.au) The groundwater supply at the remote Aboriginal community of Ngukurr in the eastern Northern Territory is becoming increasingly saline. A groundwater investigation was conducted by the Water Resources Branch of the Northern Territory Government in order to identify the source of salt affecting the current borefield and to identify an alternative groundwater supply. The community has a water requirement of IML/day. Ngukurr is situated on the upper estuarine reaches of the Roper River which experiences increased salinity in the late Dry season due to evapoconcentration and excessive turbidity in the Wet season due to mobilisation of sediments. This renders the river water unpotable for a significant portion of the year. The investigation area covers Proterozoic Nathan and Vizard Group geology comprising sandstone, basalt and dolostone. Downhole geophysical logging, EM31 ground electromagnetics and VLF techniques assisted stratigraphic interpretation and fracture targeting. Of significance were the extent of clays in the Roper palaeochannel and a perched aquifer in the Yalwarra Volcanics basalt. Alternative aquifers were identified and three production bores were constructed at 2km, 2.8km and 6km from the current borefield.
Australian Earth Sciences Convention 2008
235
236 ABSTRACTS afphafoeticai!y by surname of presenting author
Gem Corundum Sources, West Pacific Margins, Links to Former Spreading Rifts. F.L. Sutherland ^ LT. Graham^ Khin Zaw^ ^School of Natural Sciences, University of Western Sydney, Penrith South DC, NSW 1797 ^School of Biology, Earth & Environmental Sciences, University of NSW, Sydney NSW 2052 ^Centre of Excellence in Ore Deposits, University of Tasmania, Hohart, Tas 7001 Many gem corundum deposits lie along continental edges to former spreading rifts behind West Pacific arcs (South New Zealand, East Australia, Southeast Asia, East China, and East Russia). Much corundum comes from sub volcanic magmatic and metamorphic sources via basalt transport. Corundum can be categorised through inclusion mineralogy, trace element contents and ratios (Cr/Ga, Ga/Mg) and O isotope (d^^O) values. U-Pb isotopic dating of syngenetic inclusions, particularly zircon, indicate magmatic corundum may pre-date the carrier basalts by <1 to >70 myrs. Such sapphires suggest syenitic to ne syentic sources. Metamorphic sapphires and rubies suggest derivation from plumasitic or granulitic sources; they do not match ruby and sapphire found in carbonates within the Asian fold belts, as those corundums have distinctly high d^^O values. The magmatic sapphires have several postulated sources. In some regions, host basalt geochemisty suggests magmatism from metasomatis ed (amphibolised) mantle, which is also capable of generating minor volume corundumcrystallising salic melts. Higher d^^O values among these corundums, also indicate hybrid, crystal origins. A gem-forming process is proposed, linked to continental margins over-riding former spreading root zones (thermal mantle metasomatising events). In East Australia, magmatic sapphire forming events are relatively older (<85 >2 Ma) and match progressive northern lithospheric drift over old Tasman-Coral Sea sutures. In Southeast Asia and East China sapphire formation events are generally younger (<30 >0 Ma) and match easterly lithospheric drift over old South China and Japan Sea sutures. Thus, deep root zones for former, but now detached spreading floors may provide ascending thermal fluids and melts for facilitating salic gem formation and basalt magmatism beneath migrating continental plates.
Australian Earth Sciences Convention 2008
A genetic model for regional zonation and evolution of mineralized pegmatites from the Archaean Wodgina pegmatite district, Pilbara Craton, Western Australia. M.T. Sweetapple^ P.L.F. Collins^ and G.R. Lumpkin^ ^Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth W.A. 6845 ^ Materials Division, ANSTO, PMB 1, Menai, NSW. 2234 (m.sweetapple(d),exchange, curtin. edu. au) Regional zonation between different types of rare metal pegmatites within single pegmatite fields or districts are well documented world-wide, but have been poorly explained to date. In the Archaean Wodgina pegmatite district there is a regional zonation between groupings of albite, albitespodumene and beryl-columbite pegmatite types. The albite and beryl-columbite pegmatites are hosted in mafic -ultramafic sequences and the albitespodumene pegmatites are hosted in a metasedimentary sequence within a greenstone belt. The albite-spodumene pegmatites include the world-class Mt. Cassiterite tantalum pegmatite. Strong spatial, geochemical and geochronological evidence indicates that these peraluminous LCT rare metal pegmatites of the Wodgina district were derived as high level fractionates of the Numbana Monzogranite of the 'younger granite suite' (2880-2830 Ma). In the model presented, the three pegmatite groups have an unconventional regional vertical zonation. The sheeted Mt. Cassiterite pegmatite group is interpreted to have been derived from underlying less-fractionated pegmatite dykes intruding shear zones. These dykes have been derived in turn from a cupola-like zone of pegmatitic granite underlying the greenstone belt. The less-fractionated beryl-columbite pegmatite group on the outer edge of the greenstone belt adjacent to the monzogranite are equivalent to the dykes underlying the Mt. Cassiterite pegmatite group. Vertical zonation within the Mt. Cassiterite pegmatite group indicates an upward concentration of increasingly sodic and volatile-enriched fractions. Conventional crystal-liquid fractionation is interpreted to have been enhanced by liquid-state processes. The albite type Wodgina mainlode pegmatite was in turn derived from the upper parts of the Mt. Cassiterite pegmatite due to separation of a residual sodic fraction from a highly fractionated semi -consolidated melt.
ABSTRACTS 237 presenting author
alphabetically by surname of
The Geotourism Potential Investigation of Kashmar Township (Northeast of Iran)
The Creation Ability of Tsunami in the South Caspian Basin (North Iran)
Morteza Taherpour Khalil Abad^ Ibrahim Fazelvalipour^, Habib Allah Torshizian^, Mitra Taherpour Kahlil Abad^
Morteza Taherpour Khalil Abad^ Ardaln Fazel Valipour\ Mitra Taherpour Khahl Abad\ Morteza Taherpour Khalil Abad^
^Islamic Azad University, Mashhad branch, department of geology (mortezataherpoor@yahoo. com) Islamic Azad University, Mashhad branch, faculty of science, department of geology ^Islamic Azad University, Mashhad branch The remains of natural and human activities in some parts of the earth register as geopark. Actually, geopark is one or more geological phenomenon which is important from ecological, historical, cultural and archeological view. The aim of geotourism description in an area and creating a geopark is trying to keep the earth's inheritance and locality the economic of the area. Iran with an old history, diversity of the environment and a lot of geological phenomenon has a great potential in creating geoparks. From this point of view, we can divide it into 5 geotourism area which are North, South, East, West and Central of Iran. One of the deposed area is Kashmar which is located in Kharasan Razavi province in northeast of Iran. This area because of the nearness into the desert is hot and dry. The main rocks of the area are volcanic rocks and from stratigraphical view, there are Paleozoic (Cambrian - Ordovician - Silurian - Devonian), Mesozoic (Triassic Jurassic - Lower Cretaceous) and Cenozoic (Middle Eocene - Upper Miocene) units. There are Ophiolithic complex outcrops in the Northwest of this area. The volcanic rocks of the area are because of the activity of the Iran's first volcanic which are located in this part. The area has an active tectonic because of two main strike-slip faults (Darouneh & Taknar faults). The area is rich of mines like bentonite, kaolin, malachite, iron-ore and etc. the other geological point in the area is hot-water spring which called Garmab and is located in Khalil Abad (a town which depends into Kashmar township).
^ Islamic Azad University, Mashhad Branch, Khorasan province, Mashhad City, Rahnamaei Street, Abousaeid Abolkheir Ave., plaque: 143, Iran 9183996898 (mortezataherpoor@yahoo.com, maharattadris2@yahoo.com ) Earthquakes happen because of sudden releasing of the gathered strain energy in rocks. Although the time that earthquakes happen is within seconds, it is caused by a process that has happened slowly under the ground before. As we know, Iran is located on the Alp-Himalayan seismic belt and has the high seismic potential and because of the movements of the Arabian plateau toward northeast and Indian plateau toward north, so it is correct to say that the earthquake's distribution in Iran is large and wide, when earthquake happens, it releases considerable elastic energy in the focal zone, but due to the structural differences and heterogeneous environment, the ways of distribution of energy in various areas are different. The Caspian sea has been interesting to and studied by geologists and geophysicists since many years ago. The Caspian sea block has a rather low seismic rate, but the neighboring areas are very active. In this paper, we have studied the process of the releasing energy in the Caspian sea region from 36 to 42 degrees northern latitude and from 48 to 57 degrees eastern longitude, with Using of local data (Mazandaran Seismic Network), we studied systematic and historical data of GuttenbergRichter coefficients, the most probable seismic rate (seismic risk), return period and distribution of energy in the region. Although in the decade of 1960's, with respect to other regions, east and northwest part of the southern Khazar block have released much energy and were active in seismic, but in decade 70-80 they were less active and in decade 90, the northwest part became active again and great energy has been released in the region. We studied the tsunami in this area by using experimental relations and concepts which are governing on the region and faults and mud volcanoes and also diapirism phenomenon.
Australian Earth Sciences Convention 2008
238 ABSTRACTS alphabetically by sumama of presenting author
Customised Products Derived Using Airborne Electromagnetic and Hydrogeological Data to Assist in Land Use Management Along the Murray River in New South Wales and Victoria, Australia. Kok Tan\ Heike Apps\ Kenneth Lawrie^ ^Geoscience Australia. GPO Box 378, ACT 2601. Australia. (kokpiang.tan@ga.gov.au) Extensive areas along the Murray River trench and surrounding mallee plains are under cultivation, either irrigated or dryland farming. The associated environmental and land management issues include potential irrigation impacts on salinisation of the floodplain and river, rezoning of new irrigation developments away from the river to low impact areas, and conservation of forests and sustaining wetlands with the employment of artificial flooding. The success of managing these issues is underpinned by the availability of comprehensive biophysical datasets. Recendy airborne EM data, using Fugro's Resolve frequency domain system, have been acquired over 5 study areas along the middle to upper reaches of the Murray River. These areas include LindsayWallpolla, Nangiloc-Colignan-Hattah, LiparooRobinvale-Boundary Bend, Nyah-Speewa, and Barr Creek-Gunbower. The AEM data are processed using a holistic inversion method to derive various depth slice intervals, which are tilted based on the average floodplain surface gradient along the river. Together with existing literature on the hydrogeology, borehole information and litho-petrophysical results from new drilling program, these raster data form the basis of several customised GIS products to assist in land management issues. These products include the river flush zone map, conductive groundwater map, Blanchetown Clay distribution and thickness, extent of Coonambidgal Formation, map of potential groundwater mounding and perching, and near surface salt store. This paper presents the methods of deriving these maps, models and results, including the presence of a deep flush zone between Liparoo and Robinvale.
Victoria's Proterozoic Basement Intimately Controlled the Distribution of its Coastal Petroleum Basins and the Subsequent Cainozoic Landscape Evolution of the Highlands David H Taylor^ , Geoffrey O'Brien^ ^GeoScience Victoria. GPO Box 4440 Melbourne. (david. taylor@ dpi. vie. gov. au) Australian Earth Sciences Convention 2008
There are three petroleum basins of different character off the Victorian coast: the Otway, Bass and Gippsland. These Basins and the inboard landscape evolution were responses to Gondwanan continental break-up. Marked east-west variation in the development of both the basins and the highlands appears to have largely been controlled by Proterozoic basement under central Victoria. This 'Selwyn Block' is contiguous with Proterozoic crust exposed southward in Tasmania. With regard to basin formation, rifting preceded smoothly along the southern margin of Australia to form the Otway Basin. This region has extensive basin development over thinned continental crust to suggest a lower plate margin. Rifting failed to successfully propagate across the Selwyn Block. Limited rifting here led to the Bass Basin, whilst true continental separation was transferred southward to go around the bottom of Tasmania/Selwyn Block. The Gippsland Basin lies east of the Selwyn Block. Its development reflects initial southern margin break-up overprinted by Tasman Sea opening along the eastern margin of Australia which is upper plate. The landscape evolution in the highlands also reflects the distribution of the Proterozoic basement. West-central Victoria is underlain by basement and was also a lower plate in break-up. Here uplift was subdued and remnants of old landscapes are widely preserved. There appears to be remnants of prebreakup landscapes, a widespread early Cainozoic post-breakup landscape, and a well developed middle Cainozoic 'deep lead' drainage system - all being dissected by the current drainage. In the east, uplift was much more vigorous since this region has no Proterozoic basement and was an upper plate. Uplift and erosion has completely removed many of the older surfaces. The oldest surfaces preserved are 'high plains' remnants that are most likely equivalent to the young 'deep leads' surface in the west.
Extremes of Igneous Fractionation in the Moon G. Jeffrey Taylor^ ^Hawaii Inst, of Geophysics and Planetology, SOEST, Univ. of Hawaii, Honolulu, HI 96826 USA (gjtaylor@higp. Hawaii, edu) Evolved lunar rocks are important for both understanding the formation of the lunar crust and as potential resources when humans setde the Moon. By "evolved" lunar scientists mean rocks that have experienced extreme igneous differentiation through extensive fractional crystallization. Evolved rocks have high concentrations of potentially useful elements such as the rare earths (REE), Y, P, Zr, Nb, K, Li, Th, and U; they are often described by the term "KREEP," which refers to enrichments in K, the REE, and P. Not only were the magmas from
ABSTRACTS alpfiabetlcally by surname of presenting author
which evolved rocks crystalhzed rich in these elements, but crystallization further concentrated them into host minerals, such as Zr in zircon, P and the REE in phosphate minerals, and K and Li in Kfeldspar. Rock types include KREEP basalts, a variety of alkalic rocks, quartz monzodiorites, and granites. Granites are not like terrestrial granites: they are water-free, crystal size is only about 1 mm, and they do not form large batholiths. Evolved components are also represented among mineral clasts in impact melt breccias. Chemical compositions indicate that formation involved fractionation of late-stage phases, such as phosphate minerals, and silicate liquid immiscibility, possibly accompanied by separation of the two chemically-distinctive melts from one another. The rocks record processes that operated in the lunar magma ocean, the vast magma body that surrounded the Moon when it formed, and in magma produced subsequently by melting of magma ocean products. Unraveling the details of all this melting and crystallization is important to understanding the initial formation and igneous evolution of the lunar crust. Once lunar settlement expands beyond an outpost and there is a need for more commodities than bulk regolith, solar wind volatiles, or oxygen produced from the regolith, evolved rocks could become important ores.
The Paddy's Flat Gold District (Murchison, W.A): Insight Into Rheologically and Structurally Controled Gold Mineralisation. Thebaud. N. ^ and Hollingsworth, D.^ ' Center for Exploration and Targeting, UWA, 35 Stirling Highway, Crawley, m 6009 (nthebaud@cyllene. uwa. edu. au) ^Mercator Gold Australia Pty Ltd., Applecross, WA 6153 (david.hollingsworth@mercatorgold.com.au) In the North-West of the world class gold producing Yilgarn craton lies the Murchison Goldfield (Western Australia). Several rich deposits mined since the turn of the 1 c e n t u r y advocate for the attractive prospectivity of this neo-Archaean terrane and recent exploration and mining activities conducted by Mercator Gold Australia have rejuvinated this long-neglected terrane. Located in the northern part of the Murchison goldfield, the Paddy's Flat District has a recorded historic production of ~2 Moz of gold. The Paddy's Flat District is situated on an N-S trending, steeply E dipping shear on the north western limb of an upright isoclinal fold known as the Polelle syncline. It is hosted in a strained and metamorphosed volcanic and minor sedimentary sequence. Mineralisation within the Paddy's Flat District is associated with a wide range of lithologies including: (i) intermediate to felsic extrusive
volcanics, (ii) intrusive porphyrytic microgranite, (iii) ultramafic volcanic assemblage and (iv) ironrich banded chert. Mineralisation is highly structurally controled by the Paddy's Flat shear zone which provided pathways for the mineralising fluid. Regardless of the lithological composition, the mineral assemblages associated with mineralisation contain varying combinations of quartz, carbonate (ankerite, siderite, magnesite), sulphides (pyrite, arsenopyrite), fuchsite and sericite suggesting an homogeneuos fluid source. At Paddys Flat the mineralisation is spatially associated with rheologically competent units or with domains located at the boundary between rheologically distinct lithologies within the main shear. The fluid pathways provided by the shear zone and the rheological contrast are suggested to be key parameters in the formation of economic lode gold deposits.
Three-Dimensional Magnetotelluric Imaging of the Central-Western Gawler Craton Stephan Thiel^ Rachel Maier^, Graham Heinson^ Kate Selway^ Stewart Greenhalgh^, Nick Direen^ ^ School of Earth and Environmental Sciences, University of Adelaide, Adelaide SA 5005 (Stephan.Thiel@ adelaide.edu.au,Rachel.Maier@ ade laide. edu.au, Graham, heinson @ adelaide. edu.au, Kat e. Selway @ adelaide. edu.au , Nick. Direen @ adelaide. edu. au) School of Chemistry and Physics, University of Adelaide, Adelaide SA 5005 (Stewart. Greenhalgh@ adelaide. edu.au) Long-period magnetotelluric (MT) data were collected over the last four years along a line across the Nuyts and Fowler Domain (with about 15 km site spacing) and in a 2-D grid across the central and western Gawler Craton (with 100 km site spacing) in South Australia. The main outcome of this project is an apparent resistivity model of the Gawler Craton for the crust and upper mantle, which can be jointly interpreted with existing gravity and TMI data to achieve a better understanding of the nature of the deep Gawler Craton crust and mande. MT data was analysed using 2-D and 3-D inversion routines, inverting both vertical magnetic fields and electrical impedance tensor information. The models show good correlation with potential field datasets in most regions. Sedimentary basins are conductive and distort the magnetotelluric impedances. However, information could still be retrieved from basement geology, using robust phase tensor analysis and constrained inversion. Results from the 2-D inversion across the Fowler and Nuyts Domain indicate a resistive core continued next page... Austraiian Earth Sciences Convention 2008
239
240 ABSTRACTS alphabetically by surname of presenting author
underneath the Nuyts Domain, representing the source region of the St. Peters Suite granitoids. The Fowler Domain is represented by a 10-20 km thick sequence of more conductive material, which is truncated by a crustal conductor to the west. The crustal conductor spatially coincides with sedimentary sequences of the Eucla Basin.
RIO Tinto Iron's concealed high grade #2 lens; product of hypogene and hydrothermal fluid processes, Paraburdoo Western Australia.
Neil B. Thompson^
^ Centre for Exploration Targeting, School of Earth and Geographical Science, University of Western Australia, Crawley, Western Australia, 6009 Australia (thornwOl@student.uwa.edu.au)
Canning Basin Oil and Gas Potential
^ ARC Energy Limited, 679 Murray Street, West Perth, Western Australia 6005 (neilthompson@ arcenergy. com. au) Petroleum exploration began in the Canning Basin in the early 1920s. 250 wells have since been drilled onshore and 79,000 km of seismic data have been acquired over 500,000 sq km. A comprehensive review indicates that many of the wells have significant oil and gas shows and that the basin remains substantially under-explored with limited valid structural and stratigraphic tests. The low oil price in the mid 1980s to late 1990s coupled with remoteness and the small size of pools in the primary exploration area has meant that exploration has languished. In 2008 the dynamics of exploration in the basin has now been transformed by the new reality of high oil prices, and the need to develop domestic gas resources in Western Austraha. Exploration targets in the basin are varied in both area and age. In the north, the Fitzroy Trough is still considered one of the most prospective areas due to its proximity to the oil-fields of the Lennard Shelf, large central anticlines and the knowledge that most of the known hydrocarbons were generated in the trough. Other prospective areas include the adjacent Jurgurra and Barb wire Terraces, and the Broome Platform. In the south, exploration is targeting world class Ordovician source rocks and associated reservoirs in sub-salt plays, encouraged by the intersection of a significant, but tight, oil column in Looma 1 by Shell in 1996. These salt related, stratigraphic and structural plays in the Kidson and Willara Sub-basins offer tempting large oil targets with analogues to other major Palaeozoic hydrocarbon basins from around the world. The key to success in the basin has been thought to be the recognition of traps that were in place prior to the Permian, the time of the last main period of generation and migration. Subsequent early Mesozoic structural inversion has breached many earlier traps and created numerous structures, thought to be too late to capture any hydrocarbons. However evidence of secondary migration to some of the late features does exist and many of these younger traps with new seismic mapping have strong merit for exploration drilling. Reservoir quality is also an important issue, there are many tests that have proved to be tight or have intersected rocks with very low deliverability. These problems can be overcome with modern reservoir characterization, horizontal drilling and fracture stimulation techniques. Australian Earth Sciences Convention 2008
Warren Thome\ Steffen Hagemann\ David Sepe^ Hilke Dalstra^
^Rio Tinto Exploration Pty., Ltd., 37 Belmont Avenue, Belmont, Western Australia, Australia
The 2 Lens high-grade (>63 wt. % Fe) BIFrelated iron ore body in the Paraburdoo area represents a concealed ore body about 300 meters below the original topographic surface. High-grade microplaty hematite-anhedral hematite-martite ± goethite ore is hosted by BIF of the Joffre Member within the Brockman Iron Formation. Detailed diamond drill core-logging identified three distinct hydrothermal alteration zones of variable width (0.5-30m): (1) Distal magnetitecalcite-iron silicates-anhedral hematite-pyrite zone, (2) Intermediate magnetite-dolomite-iron silicatesanhedral hematite-pyrite ± microplaty hematite zone, and (3) Proximal magnetite-anhedral hematitedolomite-iron silicates- microplaty hematite zone. Petrographic observations, microthermometric measurements and ion chromotography on quartz and carbonate from veins associated with hypogene alteration (V2-V6) showed that the hydrothermal fluids were warm (~190°C) basinal brines (9-35 eq. wt% CaCls/NaCl) with Ca>Na>K. The high CI/Br, low Na/Br ratios and high-salinity of the fluids suggest that one fluid population are likely evolved basinal brines. A two-stage hypogene alteration model is proposed for the formation of the 2Lens high-grade iron ore body. Stage 1 involves the interaction of a warm (190°C) basinal brine (9-35 eq. wt% CaC^ with Ca>Na>K and interpreted meteoric waters (<5 eq wt% NaCl with the unmineralised BIF of the Joffre Member. The BIF is transformed into a magnetite-carbonate-iron silicate rock. Stage 2 involves the interaction of modified meteoric water of low temperature (estimated to be <120''C) and sahnity (<5 eq. wt% NaCl). This process involves the dissolution of carbonate, remobilization of phosphorous, and oxidation of remaining magnetite to martite. The results from this work provide new insights in the fluids responsible for the transformation of unmineralised BIF to high-grade ore in the 2 Lens deposit at Paraburdoo. The work also demonstrates the control of normal faults that provide fluid pathways for hypogene fluids from the underlying Wittenoom Formation to interact with the BIF formations. Ultimately given the correct
ABSTRACTS 241 aiphabeticaify by surname of presenting
mineralising conditions, large high-grade iron deposits have the potential to exist deep beneath unmineralised cover sequences.
The Effects of Crystal-Plastic Deformation on the U, Th, Pb, REE and Ti Geochemistry of Zircon Nicholas E. Timms^ Steven M. Reddy^, Peter D. Kinny\ Desmond Moser^, Alexander Nemchin^ P. Joseph Hamilton^ ^ The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia. (n. timms@curtin. edu. au; s. reddy@curtin. edu. au; p. kinny@curtin. edu. au; a. nemchin@curtin. edu. au; p. hamilton@curtin. edu. au) ^ Department of Earth Sciences, University of Western Ontario, London, Ontario, N6A 5B7 Canada (desmond.moser@uwo.ca) The trace element, radiogenic isotope and stable isotope geochemistry of zircon (ZrSi04) is extensively used for constraining the nature and timing of Earth processes throughout geological history. This widespread usage is underpinned by a thorough understanding of the mechanisms by which zircon geochemistry may be modified. One potentially important but generally overlooked mechanism, is the modification of zircon diffusivity via the formation of deformation-related fastdiffusion pathways throughout the mineral lattice. Electron backscatter diffraction (EBSD) analysis provides a means of quantifying lattice orientations and allows the recognition of low-angle boundaries associated with dislocation formation and migration. Application of this technique to zircons from a range of different geological environments (samples of mantle xenoliths, continental crust, oceanic crust & lunar rocks) indicates that the crystal-plastic deformation of zircon is common. Integration of quantitative orientation maps, derived by EBSD, with chemical data obtained from electron microprobe, cathodoluminescence and ion microprobe analyses, shows that U-Th, Pb REE, and Ti chemistries of zircon may be modified in the vicinity of deformation-related microstmctures. The extent of this modification is dependant upon a number of factors, including the element concentration in the original zircon, the presence of a reservoir for geochemical exchange and the geometry of dislocations and low-angle boundaries. These resuhs provide some new constraints on geological processes, for example allowing U-Pb systematics to be directly linked to the timing of lower crustal deformation. The integration of quantitative micro structural and microanalytical techniques therefore provides a new approach to unlocking zircon as a geological tool.
author
Structural Controls And U-Pb Age Constraints For Gold Mineralisation at Yaloginda, Murchison Province, Western Australia. Nicholas E. Timms\ David Hollingsworth^, Peter D. Kinny\ Steven M. Reddy\ Chris Clark^ The Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University of Technology, GPO Box UI987, Perth, m 6845, Australia. (n. timms@curtin.edu.au; s.reddy@curtin.edu.au; c.clark@curtin.edu.au) ^ Mercator Gold Australia Pty Ltd, Applecross, Perth, WA 6153, Australia. (david.hollingsworth@ curtin. edu.au) This study presents detailed geological field mapping of numerous (n = 12) gold deposits in the Yaloginda area, a greenschist facies greenstone belt 12km south of Meekatharra, east of the large-scale NW-trending dextral Meekatharra shear zone and north of the Archaean Norie pluton. Mapping shows that the location of gold mineralisation at Yaloginda is hosted in a range of rock types and strongly controlled by complex and heterogeneously distributed macroscopic structures. Sparsely preserved early regional-scale inclined, isoclinal folds with heterogeneously developed layer-parallel foliation is followed by upright NNENNW trending folds with hinges that plunge shallowly to the N and S. Progressive deformation of upright folding has led to the development of steeply-dipping, dominantly reverse dextral fault/shear systems with moderate strike continuity approximately parallel with the fold axial planes. Gold mineralisation is hosted by complex overprinting of ductile (shear zone style) and britde (lode style) structures. In the shear zone style mineralisadon, pervasive zones of metasomadsm and associated low-grade gold mineralisadon (< 0.7 g/t Au) have resulted from gold-bearing fluid that has exploited the vertically connective fault/shear systems. Vein-related high-grade lode gold is associated with zones of intense, variably orientated quartz carbonate +/- chlorite veining, commonly with sulphides within veins and/or their selvedges. Such high-grade lodes tend to overprint rocks with coarse textures at structurally complex sites. Numerous small-scale felsic porphyry dykes and sills with different phenocryst phases have intruded along and across structures that have controlled gold mineralisation early during their development. SHRIMP U-Pb dadng of zircon from these intrusions provides dming constraints on important gold-hosdng structures. The results are compared with intrusion ages of granite in the immediate vicinity of the greenstone belt. The results are also compared with U-Pb ages of similar porphyries in the Eastern goldfields to the southeast. Australian Earth Sciences Convention 2008
242 ABSTRACTS alpliafoetlcally by syffiame of presenting author
Zircon Deforms in a Magma Chamber! Nicholas E. Timms\ Steven M. Reddy\ P. Joseph Hamilton^ Helen R. Smyth^ ^ r/ze Institute for Geoscience Research (TIGeR), Department of Applied Geology, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia. (s. reddy @curtin. edu. au; n. timms@curtin. edu. au; p. hamilton@curtin. edu. au) " CASP, 181A Huntingdon Road, Cambridge, CB3 ODH, UK. (helen.smyth@casp.cam.ac.uk) An undeformed glomeroporphyritic andesite from Java, Indonesia, contains zoned plagioclase and amphibole glomerocrysts in a fine-grained groundmass and records a complex history of adcumulate formation and subsequent disaggregation and magmatic replenishment. A suite of xenocrystic zircon records Proterozoic and Archaean dates whilst a second population of zoned, euhedral, igneous zircon yields a SHRIMP crystallisation age of 9.3 ± 0.2 Ma. Quantitative microstmctural analysis (via electron backscatter diffraction - EBSD) show no deformation in the inherited xenocrysts, but intragrain orientation variations of up to c.30° in over 80% of the young zircon population. These variations are typically accommodated by both progressive crystallographic bending and discrete low angle boundaries that overprint growth zoning. Misorientation axes of adjacent analysis points in EBSD maps are dominantly parallel to <001>, and less commonly <100>, and account for the dispersion patterns of crystallographic orientations. These observations are consistent with zircon deformation by dislocation creep and the formation of tilt and twist boundaries associated with the operation of <001>{100} and <100>{010} slip systems. The restriction of deformation microstmctures to glomerocrysts and the young magmatic zircon population and the absence of deformation within the groundmass and inherited zircon grains, indicate that zircon deformation took place within a low melt fraction crystal framework stage prior to fragmentation during magmatic replenishment of the magma chamber. These results provide the first evidence of crystal plastic dislocation creep in zircon associated with magmatic processes and indicate that the development of crystal-plastic microstmctures in zircon is not restricted to high-strain rocks. Such microstmctures have previously been shown to enhance bulk diffusion of trace elements (U, Th and REE) in zircon. The results therefore have significant implications for the interpretation of geochemical data from magmatic zircon and the trace element budgets of melts due to the potential enhancement of bulk diffusion and dissolution rates.
Australian Earth Sciences Convention 2008
The 'Lusi' Mud Eruption, Sidoarjo, East Java - A Unique Geological Disaster Mark Tingay^ ^ School of Earth & Environmental University of Adelaide, SA (mark, tingay @ adelaide. edu. au)
Sciences, Australia
Early in the morning of the 29th of May 2006, hot mud started erupting from the ground in the densely populated Porong District of Sidoarjo, East Java. With initial flow rates of approximately 5000 cubic meters per day, the mud quickly inundated neighbouring villages. Over 18 months later and the 'Lusi' (coined from 'Lumpur Sidoarjo') eruption has increased in strength, expelling over 0.04 cubic kilometres of mud at rates of up to 170,000 cubic metres per day. The mud flow has now covered over 700 hectares of land to depths of up to 17 meters, engulfing eight villages and displacing approximately 40000 people. The Lusi eruption is an example of a mud volcano, a relatively common feature in sedimentary basins that have been rapidly deposited or are in tectonically active areas. However, controversy remains regarding what triggered the eruption. Some scientists believe the eruption was triggered by the Magnitude 6.3 Yogyakarta earthquake that occurred on the 27th of May. However, other researchers believe the mud eruption resulted from a drilling accident in the adjacent Banjar Panji-1 exploration well. This presentation reviews the events leading up to and following the East Java eruption and examines the competing theories about what triggered the eruption.
Increasing the scope of mineral prospectivity in the Cobar-Bourke region, New South Wales Gary R B u r W , Steven J Trigg\ Lorraine M Campbell^ ^ Geological Survey of New South Wales NSW Dept Primary Industries 161 Kite St, Orange NSW 2800 (gary. burton@dpi. nsw.gov. au; Steven. trigg@dpi. nsw.gov. au; lorraine. campbell@dpi. nsw.gov. au) The geology of the Cobar-Bourke area in central New South Wales consists chiefly of Ordovician Girilambone Group overlain by and in faulted contact with rocks of the Late Silurian to Early Devonian Cobar Supergroup. Known mineral deposits within the area consist of copper deposits within the Girilambone Group and Au±Cu±Pb, Zn, Ag Cobar-type deposits within the Cobar Supergroup.
ABSTRACTS afphabaticaffy by surname of presenting author
Recent geological mapping and reconnaissance field work by the Geological Survey of New South Wales within the Cobar-Bourke area has delineated previously unrecognised or disputed fault-bounded synclinal keels of Cobar Supergroup rocks. The Mount Boppy gold deposit occurs within a similar sliver and has produced over 13 t of gold. SHRIMP U-Pb zircon dating of felsic intrusive rocks associated with tin skarn mineralisation at the Doradilla prospect indicates a Middle Triassic age. Similarly aged tin-mineralising granites are known from the New England area of New South Wales. It is therefore possible that further tin-mineralising granites are present at depth in the Brewarrina area with potential for vein and pegmatite-hosted tin deposits. Company drilling has intersected andesites beneath approximately 100 m of cover to the northeast of Bourke. They have arc-type characteristics and are associated with a northeasterly trending magnetically high zone which may be a remnant volcanic arc. Porphyry style Au±Cu and epithermal to mesothermal Au mineralisation could be associated. A further result of the mapping is that lithological patterns and conodont age determinations suggest a possible stratigraphic differentiation of the Girilambone Group. Reconnaissance work indicates that a quartzmagnetite-haematite rock associated with mineralisation at the Tritton copper deposit is chertlike and may be syngenetic. It follows that the establishment of a stratigraphic subdivision for the Girilambone Group may assist in delineating areas prospective for Tritton-style mineralisation.
Assembling the western North Australian Craton: Linking the King Leopold, Halls Creek, Granites-Tanami and Arunta orogens L M. Tyler\ S. Sheppard\ L. Bagas 1,2 ^ Geological Survey of Western Australia, Mineral House, 100 Plain Street, East Perth WA 6004 {ian. tyler@doir. wa. gov. au, steve.sheppard@doir.wa.gov.au) ^ Centre for Exploration Targeting, School of Earth and Geographical Sciences, University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (leon. bagas @ doir. wa. gov. au) The King Leopold and Halls Creek Orogens are interpreted to be part of a larger collisional orogen that sutured the Kimberley Craton with the rest of the North Australian Craton. At c. 1872 Ma a turbidite-filled rift formed marginal to the Kimberley Craton. This was intruded by granitic and mafic-ultramafic rocks, and together with associated felsic volcanic rocks, was deformed and metamorphosed during the Hooper Orogeny (18651850 Ma) when a c. 1865 Ma oceanic island arc was
accreted outboard of the rift. Rifting of the accreted arc at 1855-1845 Ma was accompanied by the emplacement of layered mafic-ultramafic intrusions, the intrusion of tonalite sheets, peak granulite facies metamorphism, and the eruption of felsic and mafic volcanic rocks. Along the North Australian Craton margin a 1910-1880 Ma passive continental margin sequence evolved into to an active margin setting at c. 1855-1845 with the development of a foreland basin. Collision and suturing took place during the 1835-1805 Ma Halls Creek Orogeny. In the Granites-Tanami Orogen, Archean to early Paleoproterozoic basement is preserved underlying a c. 1864 Ma deep water sedimentary rock, turbidite and mafic volcanic-dominated sequence deposited in an extensional, back-arc setting to the Halls Creek arc. Further sequences of deep water sedimentary rock and turbidites were deposited in a series of foreland basins during the 1835-1810 Ma Tanami Orogeny, which may represent far-field effects of the Halls Creek Orogeny. In the Arunta Orogen, the Aileron Complex is dominated by turbiditic rocks probably deposited at c. 1835 Ma and is separated from the GranitesTanami Orogen by a fossil (>1864 Ma) suture zone. The Warumpi Complex accreted to the southern margin of the North Australian Craton between 1690-1610 Ma during the Liebig Orogeny, prior to colUsion with the Mawson Craton at 1590-1570 Ma. The geological histories of the King Leopold, Halls Creek, Granites-Tanami, and Arunta orogens are linked by a common plate tectonic system with progressive cratonization of the North Australian Craton from north to south (1865 Ma to 1590 Ma).
Petroleum Hydrogeology: Application to Groundwater Management J. R. Underschultz^ ^COICRC at CSIRO Petroleum, Box 1130, Bentley WA. 6102. Australia (James.underschultz@csiro.au) Since King Hubbert published "Entrapment of petroleum under hydrodynamic conditions" in the American Association of Petroleum Geologists Bulletin in 1953, the study of Petroleum Hydrogeology has had growing apphcation towards understanding aspects of petroleum systems such as long distance hydrocarbon migration, hydrodynamic traps, tilted hydrocarbon-water contacts, membrane seal capacity of top seals and fault seals, and hydrocarbon biodegradation. There has also been growing application in over-pressure prediction, identification of bypass pay, and prediction of production compartmentalisation. Many of the techniques developed in petroleum hydrogeology research, has application to the groundwater resources industry; but what is the added value? Australia has a growing track record of continued next page.. Australian Earth Sciences Convention 2008
243
244
ABSTRACTS alphabeticalty by surname of presenting author
multidisciplinary research on hydrodynamic processes in the subsurface related to water resources. This is partly driven by the nature of Australia's Sedimentary Basins and the distribution of water and hydrocarbon resources within them. Many of the fresh to brackish groundwater resources occur at significant depth, such as the Great Artesian Basin, the Perth Basin and the Gippsland Basin. In the Gippsland Basin, the bulk of known hydrocarbon accumulations are reservoired in the Latrobe Gp. strata offshore. On-shore the same reservoir unit hosts significant formation water and coal resources. To adequately characterise and manage the natural resources within the Latrobe strata an approach is required where petroleum hydrogeological techniques are integrated with groundwater resources techniques. Advances in seals analysis in the petroleum domain have been aimed at pre-drill prediction of membrane (capillary) seal capacity. These same techniques can be used to estimate permeability of fault zones in the shallow subsurface aquifers. A parallel application of petroleum hydrogeology techniques has been to emerging requirements for CO2 sequestration. The increasing interest by governments and industry in geosequestration of CO2 punctuates the requirement for a multidisciplinary approach. Solutions for CO2 avoidance while at the same time protecting the groundwater and hydrocarbon resources, requires a range techniques and expertise. Issues of storage capacity, containment security, saline water displacement, and the need for robust monitoring and verification prose technical challenges in complex geological environments. Addressing these topics in a holistic way has the potential to solve many of the big issues around the protection and management of our water resources, the cohabitation of hydrocarbon extraction, and the need to reduce CO2 emissions.
A Volcanic Caldera Habitat For Earth's Oldest Stromatolites (C. 3.5 Ga) From The North Pole Dome, Western Australia. Martin J. Philippot^
Van
Kranendonk\
Discovery trails to early Earth — A traveller's guide to the east Pilbara. Martin J. Van Kranendonk\ Jean Johnston^ ^ Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia (martin. vankranendonk@ doir. wa. gov. au)
Pascal
^ Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia (martin. vankranendonk@doir. wa.gov. au) " Laboratoire Geobiosphere Actuelle et Primitive, Institut de Physique du Globe de Paris, Case 89, 4 place Jussieu, 75252 Paris Cedex 05, France (ph ilippot@ipgp.jussieu.fr) Results from geological mapping and a detailed study of diamond drillcore obtained from beneath the zone of oxidative weathering through the 3.5 Ga Dresser Formation in the North Pole Dome, Pilbara Craton, show that Earth's oldest stromatolites have a range of morphology and
Australian Earth Sciences Convention 2008
occupied diverse habitats within an active volcanic caldera. Petrographic observations indicate that the stromatolitic chert-barite unit consisted of interbedded micritic and stromatolitic carbonates, volcanogenic sandstones and polymict diamictites that were variably affected by multiple episodes of hydrothermal fluid circulation and variably replaced by hydrothermal minerals including silica-baritesphalerite, pyrite, and silica-haematite. Stromatolitic laminates are largely replaced by pyrite, but relict carbonate grains between pyrite crystals suggest a carbonate protolith, supporting a biogenic origin of the original rocks. Stratigraphic and fault offset analysis shows that periods of quiet-water carbonate precipitation altemated with deposition of coarse clastic rocks during periods of growth faulting related to development of the caldera. Hydrothermal fluids utilised growth faults and escaped along these pathways to the ocean floor. Shallow-water carbonates contain coniform stromatolites. In contrast, domical to wavy laminated stromatolites occur adjacent to, and downflow from, growth fault tips, most often encased in hydrothermal precipitates. This relationship, combined with sulfur isotope data, is used to suggest stromatolite growth during periods of hydrothermal fluid circulation and therefore the presence of chemoautotrophic communities, most likely organisms that disproportionate elemental sulphur (Philippot et al., 2007, Science, v. 317, p. 1534-1537). In combination with evidence of methanotrophy in subsurface hydrothermal veins from the same formation (Ueno et al., 2006, Nature, V. 440, p. 516-519), these results suggest that hfe at 3.5 Ga was already diverse and occupied several habitats.
A self-drive guidebook to the geology and landforms of the east Pilbara is being published by the Geological Survey of Western Australia as part of its plan to enhance the public knowledge of our geoheritage. The guidebook presents information for places of interest along all of the main tracks radiating out from the town of Marble Bar (some 2000 km north of Perth), to Port Hedland, Nullagine, Shay Gap and Auski Roadhouse. Stops focus on the geological history of the Archean basement (3.5-2.8 bilHon years old [Ga]), on the unconformably overlying Fortescue Group (2.78-2.63 Ga), on the regolith, and on recent landforms, and give insights into how the basement geology has influenced development of these latter features.
ABSTRACTS alphabetically by surname
1. 2. 3. 4. 5. 6. 7.
Introductory chapters cover: Welcome and how to use this book What you will need for travel in the outback Pilbara region today How rocks are formed Dating of the rocks Early Earth and deep time — Pilbara geology Trails through the Pilbara
This comprehensive and interesting guidebook helps to bring to life an ancient and fascinating part of our geoheritage.
Depositional controls on stromatolite growth in Earth's oldest-known stromatolitic carbonate platform: the 3.40 Ga Strelley Pool Chert, Pilbara Craton. Martin J. Van Kranendonk^ Kenichiro Sugitani^ ^ Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia (martin. vankranendonk@doir. wa.gov. au) ~ Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan (sugi@info. human, nagoya-u. ac.jp) The 3.40 Ga Strelley Pool Chert is Earth's oldest-known carbonate platform, deposited unconformably on >3.43 Ga rocks across the -220 km diameter of the East Pilbara Terrane. A broadly tripartite stratigraphy includes: a lower unit of up to 1 km of supermature, cross-bedded and rippled quartz-rich sandstone with a local basal beach conglomerate; a middle unit of dominantly shallowwater carbonate that is commonly stromatolitic and locally interbedded with quartz-rich sandstone and finely laminated black chert; and an upper unit of conglomerate and sandstone. Deposition was under generally shallow water conditions, with local areas of deeper water, but all sections contain a broadly recognizable and correlatable stratigraphy. Coniform to branching, columnar stromatolites occur only in areas of demonstrably shallow water carbonate deposition, suggestive of phototrophy. On steeper paleoslopes, stromatolites are asymmetric and form local biostromes. Evidence for microbial binding of loose carbonate sediment is preserved in well laminated, broadly-rippled carbonates at the terminus of the biostromes. Coarse, upward-fanning crystal splays of probable nahcolite indicate hypersaline periods and a probable C02-rich atmosphere. Small columnar stromatolites and thin microbial mats formed on shallow mud flats under possibly reducing conditions. Stromatolite growth was terminated by periods of prolonged exposure, represented by thinly laminated sediment with windblown ripples and erosional unconformities. Clasts of kerogenous organic matter in overlying sandstones support morphological evidence for stromatolite biogenicity (see M. Van Kranendonk, and also C. Marshall, 2007, in Van Kranendonk et
of presenting
author
al., (eds.), Earth's Oldest Rocks, Elsevier, p. 855877 and 897-921). Similar crystal splays in stratigraphically overlying, c. 3.0 Ga rocks, are developed in thinly bedded black chert within quartz-rich sandstones (Sugitani et al., 2003, Precambrian Research, 120, 55-79). The black cherts contain highly probable microfossils (Sugitani et al., 2007, Precambrian Research 158, 228-262). IN both of these examples, the close association of biogenic activity with shallow, evaporitic conditions is indicative of one environment of earlv life on Earth.
Early Archean tectonics and the start of modern subduction Martin J. Van Kranendonk\ Smithies^
R. Hugh
^ Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia (martin, vankranendonk @ doir. wa. gov. au) Paleoarchean high-grade gneiss terranes (HGTs) and granite-greenstone terranes (GGTs) differ as follows: - high vs. low grade; - dominandy tonalite-trondhjemite-granodiorite (TTG) gneisses vs. dominantly monzogranite; - small, dismembered supracrustal imbricates vs. widespread, thick, contiguous greenstones; - horizontal vs. vertical tectonics; East Pilbara data indicates GGT formation from deep mande plumes. Greenstones were erupted first as an oceanic plateau, which then internally differentiated to form stable condnental crust on thick, depleted lithosphere. TTG magmas derived from high- and medium-pressure melting of mafic underplate and enriched crustal sources in a nonsubducdon setdng (see Van Kranendonk et al., this symposium). Geochemical data on TTG from HGTs also preclude formadon in a steep, modern-style subducdon zone (Smithies, 2000: Earth and Planetary Science Letters 182, 115-125). However, HGT zircons show multiple growth stages over long dme periods that, together with evidence for muldple TTG formadon periods, suggests multiple meldng episodes under reladvely constant condidons; unusual for modern convergent margin setdngs. This data, in combinadon with the evidence for horizontal tectonics, is used to suggest HGT crust formation through basalt imbricadon and meldng in symmetrical downwelling counterflow zones to up welling mande plumes (cf. Park, 1997: South African Journal of Geology 100, 23-35). The intuitive concept of more abundant mande plumes to dissipate greater heat in early Earth is used to suggest that GGTs and HGTs represent end-member crust types that formed over mande upwelhngs and crustal downwellings, continued next page... Australian Earth Sciences Convention 2008
245
246
ABSTRACTS alphabetically by surname of presenting aytHor respectively. It was only when one or both of these types of crust became large enough and developed a thick keel that counterflow zones became asymmetric and subduction commenced. The Artemis Corona on Venus is shown for comparison of how this process may have started.
Environments ot nie at ija; evidence from the East Pilbara Terrane, Western Australia. Martin J. Van Kranendonk^ ^ Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia (martin. vankranendonk@doir. wa.gov. au) Data from the East Pilbara Terrane of the Pilbara Craton suggest that life was already diverse and occupied at least 4 different habitats by 3.5-3.3 Ga. 1) Shallow water, nearshore to intertidal environments; as microbial mats and domical and coniform stromatolites. Examples include the 3.49 Ga Dresser Formation and 3.40 Ga Strelley Pool Chert. Evidence for shallow water suggests phototrophy. Stromatolites grew predominantly by precipitation, rather than by trapping and binding, and mats locally bounded the surfaces of loose carbonate sediment (Van Kranendonk et al., 2003, Geobiology 1,91-108). 2) At the mouths of, and downflow from active, lowtemperature hydrothermal fluid vents. Microbes formed wrinkly laminated mats and domical stromatolites. Sulphur isotope data suggests microbes were chemoautotrophs that preferred elemental sulphur (Philippot et al. 2007, Science 317, 1534-1537). This habitat occurs in the Dresser Formation. 3) Within low-temperature hydrothermal fluid systems in fractures in the subsurface, where Cisotope data on kerogen shows extreme fractionation indicative of methanotrophy (Ueno et al., 2006, Nature 440, 516-519). Examples include the Dresser Formation and 3.46 Ga Apex chert locality. 4) In the glassy margins of 3.35 Ga pillow basalts, where titanate-filled tubular ichnofossils indicate the presence of Archean chemoautotrophs that gained nutrients from dissolution of volcanic glass (Banerjee et al.. Geology 35, 487-490). The combined data, from multiple convergent lines of evidence, provides compelling support for a diverse microbial community at 3.5-3.3 Ga.
Austraiian Earth Sciences Convention 2008
Formation of Archean continental crust from an oceanic plateau in a nonsubduction setting: the east Pilbara example Martin J. Van Kranendonk^ R. Hugh Smithies^ D.C. Champion ^ Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia (martin, vankranendonk @ doir. wa. gov. au; hugh. smithies @ doir. wa. gov. au) ^ Geoscience Australia, GPO Box 378, Canberra ACT2601, Australia (David.Champion@ga.gov.au) The ancient East Pilbara Terrane was initiated as an oceanic plateau from 3.72 Ga and transformed, via plateau-like magmatism and intracrustal melting over a 500 My period, into mature continental crust. Processes involved in this transformation involved multiple (or pulsed) episodes of mantle melting that produced a thick crust comprised of basaltic lavas, intraplates and underplates. The presence of komatiitic lavas and ultramafic sheeted sills throughout the succession reflects the role that mantle plumes played throughout this stage. Early melting at the base of the thickened mafic crust produced minor TTG melts. These mixed with, or were assimilated by, large mafic magma batches emplaced into the crust, and these then fractionated to produce enriched tholeiitic basalt and andesite, up to c. 3.5 Ga. Subsequent high-pressure melting of mafic crust, and particularly of these enriched sources, produced voluminous TTG magmas. Incorporation of significant amounts of TTG into 3.4 Ga large mafic magma batches led to the formation of andesitic to dacitic calc-alkaline magmas. This entire succession was again recycled during 3.353.29 Ga and 3.27-3.24 Ga plume events to produce voluminous K-rich granites. The younger granites include transitional TTG-type rocks that range from Al-rich and Y-poor to Al-poor and Y-rich compositions, reflecting melting over a wide range of crustal depths. Magmatic overthickening was accommodated by extension of the upper to middle crust, as indicated by synvolcanic growth faults and dyke swarms throughout the volcanic pile. This extension facilitated periods of partial convective overturn of the upper and middle crust at the end of major volcanic episodes. Extreme depletion of the subcontinental mantle lithosphere accompanied progressive fractionation of the crust and formed a thick, stable and buoyant lithospheric keel. Together, these contemporaneous and complementary/reciprocal processes resulted in the stabilization of some of Earth's earliest lithosphere in a non-subduction setting.
ABSTRACTS alphabetically b y surname of presenting author
Issue with the Precambrian Timescale: or, Should We Stick With What We've Got? Martin J. Van Kranendonk^ ^ Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia (martin.vankranendonk@doir.wa.gov.au) The Precambrian covers >4 Ga of Earth history, which includes the onset of an oxygenated atmosphere and the development of multicellular hfe. Dividing this long period into meaningful time slices is challenging, primarily because plutonic rocks dominate and biological development was primitive and poorly preserved. Except for the Ediacaran Period, the current Precambrian timescale (Robb et aL, 2004, Chapter 9; in, A Geologic Timescale 2004, Cambridge University Press) utilizes chronometric divisions rounded to hundreds of millions of years, based on Plumb and James' (1986, Precambrian Research, v. 32, p. 65-92) broad global geodynamic scheme that ignores stratigraphic principles (cf. Cloud, 1987, Precambrian Research, v. 37, p. 257-264). Since this scheme was proposed, it has been argued that the wealth of newly acquired geoscience data should allow for a chronostratigraphic Precambrian timescale that is firmly based on stratigraphy, may include (some) golden spikes, and is better able to more accurately reflect key events in Earth history to the general public (Bleeker, 2004. Lethaia, v. 37, p. 1-4). Suggestions for a revised Precambrian timescale include: 1) a Hadean Eon, from 4.567 Ga to the age of Earth's oldest rock (4.03 Ga Acasta Gneiss); 2) a change in the Archean-Proterozoic boundary to c. 2.45 Ga, at the transition from BIFshale to clastic deposition at the top of the Hamersley Basin; 3) revised Eo-, Paleo-, Meso- and Neoarchean Eras, with stratigraphic boundaries; 4) an Eoproterozoic Era, from end Archean to the end of global glaciations and onset of redbed deposition; 5) revised Paleo-, Meso- and Neoproterozoic Eras. These suggestions will be presented to the geoscience community for discussion and developed into more firm proposals over the coming year. Pending some kind of consensus, it is hoped that formal proposals will be submitted to the lUGS by 2010.
New insights on the development of the northeastern Murchison domain, Yilgarn Craton. Martin J. Van Kranendonk^ ^ Geological Survey of Western Australia, 100 Plain St., East Perth, WA, 6004, Australia (martin. vankranendonk@doir. wa.gov. au)
Recent mapping by the Geological Survey of Westem Australia in the northeastern Murchison domain, Yilgam Craton, has identified up to 4 volcanic packages, 5 episodes of granitic intrusion, and 2 main deformational events between c. 30002623 Ma. Early crust formed at between 3034-2900 Ma, including c. 2970 Ma supracrustals in the Weld Range (volcanic package 1). >2814-2800 Ma tholeiitic basalt-felsic volcanics (package 2) are preserved in the Meekatharra area at the base of the Polelle Syncline. This is conformably overlain by the more widespread komatiitic to felsic volcanic rocks of package 3, erupted at between 2785-2747 Ma and accompanied by syn-volcanic hornblende tonalites (e.g. Cue Tonalite). Volcanic package 4 consists of another komatiitic to felsic volcanic succession erupted at 2720-2704 Ma, and accompanied by synvolcanic layered ultramaficmafic sills. Volcanism was followed by emplacement of widespread granitic rocks at 2676-2644 Ma. Early components were emplaced during D1 deformation that involved sinking of greenstones and magmatic inflation of granites at between 2676-2660 Ma. D2 structures include gold-bearing, northeast-striking dextral shear zones, north-northwest striking sinistral shear zones, and north-south zones of pure shear flattening that resulted from regional east-west compression at c. 2640 Ma. Post-tectonic granites are 2623 Ma. The similar and contemporaneous nature of events in the latter part of Murchison domain history (2720-2630 Ma) with those in the Eastern Goldfields Superterrane suggests that terrane accretion models for the craton may need to be critically re-examined. The presence of komatiites at the base of Murchison domain volcanic packages 3 and 4, as well as in Eastem Goldfields successions, suggest a plume influence on craton evolution that may be more widespread and significant than currently appreciated.
Photosynthesis in a 3.5 Ga Old Shallow Marine Depositional Environment; Clues from Carbon and Iron Isotope Systematics Mark van Zuilen^ Christophe Thomazo\ Beatrice Luais^, Pascal Philippot^ ^ Laboratoire Geobiosphere Actuelle et Primitive, Institut de Physique du Globe de Paris, CNRS & Universite Denis Diderot, France, (vanzuilen @ ipgp.jussieu.fr, thomazo @ ipgp.jussieu. fr, philippot@ipgp.jussieu.fr) CRPG-CNRS, Vandoeuvre-les-Nancy, France, (luais @ crpg. cnrs-ancy.fr) Different abiologic and biologic models exist for the oxidation of Fe(II)aq in the upper part of the Early Archean ocean. Here we discuss the origin of Ee-oxides that occur in the 3.49 Ga old Chert-BariteUnit of the Dresser Formation at North Pole (Pilbara continued next page.. Australian Earth Sciences Convention 2008
247
248
ABSTRACTS alphabetically by surname of presenting author
Drilling Project, Western Australia). This unit represents a shallow water depositional environment within a volcanic caldera, and has experienced lower greenschist-facies metamorphism. It consists from bottom to top of bedded cherts, barite-sulfide beds, and bedded Fe-rich carbonates. An underlying network of barite- and silica-feeder dikes suggests synsedimentary hydrothermal activity. Towards the top of the unit, a succession of thin alternating bands of hematite and Fe-rich carbonate occurs, that includes kerogenous laminations that resemble microbial mats. Within the carbonate bands kerogen appears to be closely associated with hematite microcrystal inclusions. Laser Raman spectroscopy confirms that the organic matter in these laminations is indigenous (it has experienced greenschist facies metamorphism). The carbon isotope ratio of these laminations 30 to -18%o) is distincdy different from that of kerogen in the underlying sihca dikes (-34 to -31%o). The hematite bands display a strong positive (-hO.l to +l%c), compared to the Fe-rich carbonates (-0.6 to +OA%c) and underlying barite-sulfide beds (0.7 to -0.4%o). These petrographic, Raman spectroscopic and isotopic observations exclude a direct hydrothermal origin of these hematite-rich bands and suggest that oxygenic and/or anoxygenic photosynthesis was directly involved in the oxidation of Fe(II)aq in this Early Archean shallow marine depositional environment.
A Record of Late Palaeoproterozoic Metamorphism and Reworking in the Cadney Metamorphics, Strangways Metamorphie Complex, Central Australia Wade. B.P.\ Hand, M \ Kelsey, D.E. \ Barovich, K M \ Scrimgeour, LR. Close, D.F.^ ^ Continental Evolution Research Group, Department of Geology and Geophysics. University of Adelaide, Adelaide, Australia, South Australia, 5005, Australia (benjamin.wade@adelaide.edu.au) ^ Northern Territory Geological Survey. GPO Box 3000. Darwin, Northern Territory, 0801. Australia {dorothy. close @ nt. gov. au) The Cadney Metamorphie package is an enigmatic suite of variably reworked calc-silicate, metapelitic, and metaigneous rocks within the Strangways Metamorphie Complex in central Australia, that have remained largely unstudied in recent times. Field and petrographic relationships provide evidence of a high-grade (orthopyroxenesillimanite-bearing) reworking event, which deforms an older (peak) migmatitic granulite facies fabrics that trend N-S in areas with limited reworking. Prior to reworking the granulite-assemblaees were Australian Earth Sciences Convention 2008
extensively intruded by ~ N-S trending mafic dykes. The reworking produced F-W trending fold systems and was associated with the development of largescale mylonite zones and km-scale sheath folds characterised by NF-plunging linear elements. Kinematic indicators within bulk of the mylonite zones indicate extensional (N and F-side down) movement. Preliminary age constraints suggest that reworking occurred at around 1690 Ma, approximately coincident with voluminous felsic magmatism in the Warumpi Province in the southern Arunta. Depositional age constraints on the metasedimentary protoliths are not well established. Minium depositional ages are c. 1725 Ma which corresponds to the timing of peak granulite-grade metamorphism. This study integrates structural data with LAICPMS detrital zircon and in-situ monazite analyses to determine the timing of the metamorphie events, the depositional age, and provenance of the Cadney Metamorphics. These constraints then direcdy feed into and inform current tectonic models of late Palaeoproterozoic Australia.
Provenance of Metasedimentary Rocks From the Entia Dome, Eastern Arunta Region, Central Australia: A Combined U-Pb SHRIMP, LA-ICPMS And Sm-Nd Isotope Study. Wade. B.F\ Hand, M,\ Maidment, D.W. ^ Close, D.F. Scrimgeour, LR. ^ ^ Continental Evolution Research Group, Department of Geology and Geophysics. University of Adelaide, Adelaide, Australia, South Australia, 5005, Australia (benjamin.wade@adelaide.edu.au) ^ Geoscience Australia, GPO Box 378, Canberra, ACT 2601, Australia.(david.maidment@ga.gov.au) ^ Northern Territory Geological Survey. GPO Box 3000. Darwin, Northern Territory, 0801. Australia (dorothy. close @ nt. gov. au) Metamorphie monazite from two metapelitic lithologies from within the Entia Dome display age populations of -1770, 1720, and 340 Ma. The age of -1770 Ma is the first direct evidence of monazite growth during the Yambah Event (ca. 1780-1770 Ma), and is attributed to high-grade contact metamorphism associated with emplacement of a local granodiorite of the calc-alkaline trondjhemite suite (CAT suite). The age of -1720 Ma is attributed to metamorphism associated with the Strangways Orogeny (1730-1715 Ma), and the Carboniferous age of -340 Ma to pardal resetting and growth of new monazite during the Alice Springs Orogeny (340-330 Ma). Sm-Nd isotope systematics of the metasedimentary rocks display a large variation
ABSTRACTS alphabetically by surname of presenting author
ranging from eNd 1750=-1.4 to -8.8. When coupled with the detrital zircon age populations, the isotopes allow for a locally derived (North Australian Craton) source for the metasedimentary rocks, however sources from the South Australian Craton cannot be excluded. Igneous zircon from a felsic intrusive of the Entia Gneiss Complex returned a weighted average age of 1778±8 Ma, interpreted as recording the crystallisation of the igneous precursor. The approximately coincident ages of metamorphism (-1770 Ma), deposition of at the metasediments (ca. 1780-1770 Ma), along with the intrusion of voluminous felsic and mafic magmatism (1778±8 Ma), suggests that the precursor to the metasedimentary rocks deposited rapidly, possibly related to the intrusion of arc-related granitoids generated by active subduction along the southern margin of the North Australian Craton.
Keys to the Production of Eastern Yilgarn Au Deposits: Mixing Oxidized and Reduced Mantle Fluids L L , _ W a l s h e \ P. Neumayr^, K. J.S. Cleverley^
Petersen^
^ pmd^CRQ CSIRO Mining and Exploration, ARRC, Perth, WA6151 (john.walshe@csiro.au) ^pmd^CRC, CET, University of Western Australia (pneumayr@cyllene. uwa. edu.au) ^pmd^CRC, CET, University of Western Australia (kjpeters @ cyllene. uwa. edu. au) ^pmd'^CRC, CSIRO Mining and Exploration, ARRC, Perth, WA6151 (james.cleverley@csiro.au) Three end-member fluids are required to account for the chemical characteristics of Eastern Yilgarn Au deposits and the spatial associations of deposits and camps with trans-crustal structures, intrusive complexes and district-scale domical structures. Fluid 1, an ambient crustal fluid, was aqueous with low concentrations of salt and volatiles. It is likely that the major reservoirs of water, late in the metamorphic history, were in syn - orogenic sedimentary basins. Fluids 2 and 3 were volatile-rich fluids that ultimately controlled the physicochemical gradients (redox, pH, activities of S, C, CI ) driving gold transport and deposition. Both were sourced from the mantle and tomographic studies have identified structure to depths of > 100 kms suggesting possible fluid pathways to at least depths of that order. Fluid 2 was of magmatic affinity, dominated by CO2 and SO2, but with capacity to transport elements such as Te, V, Mo, Bi, W and possibly K. of CO2 is estimated at -5 to -6 and of SO2 at ~ 0 consistent with a mande origin for CO2 and SO2. Radiogenic Pb and Sr? may have been acquired by fluids stored in crustal domes but
ultimately the oxidized magmatic fluids probably originated from melting of metasomatized upper mantle. Fluid 3 was a highly reduced CH4 - N2 - H2 fluid that transported acid volatiles (H2S, HCl +HF), noble gases (Ne and Ar) of mantle origin, possibly metal hydrides (e.g. NaH, MgHs, AIH3 and SiH4) and probably gold. Thermodynamic calculations suggest the reduced fluid was stable at depths greater than 300 to 400 km. Mixing of "deep-Earth" fluids with oxidized magmatic volatiles appears to be the salient mechanism of gold deposition in the crust. Mixing of "deep-Earth" fluids with ambient aqueous fluids drove district-scale acidic alteration and dispersion of Au.
Distinguishing Microbial Carbonates Using In Situ LA-ICP-MS Vital Trace Element Geochemistry: Implications For Biogenicity G r e g o r y E . W e b b \ B a l z S. K a m b e r ^ ^ Queensland University of Technology, Australia (ge.webb@qut.edu.au) ^ Laurentian University, Sudbury, Canada
Brisbane,
Determining the origin of putative microbialites is critical for understanding the early distribution of life on Earth, but increasingly, the biogenicity of ancient microbialite-like structures has been questioned. Criteria for evaluating the biogenicity of such structures include such attributes as preservation of in situ fossil microbes and/or delicate 'crinkly' mat microstructure. However, such features are rarely preserved, even in welldocumented modern microbialites. Hence, additional analytical tools are required. It has been shown recently that some undisputable microbialites (e.g., the Devonian calcimicrobe Renalcis) take up certain vital trace elements at concentrations that readily distinguish them from coeval cements and skeletal carbonates (Kamber and Webb, 2007, Geobiology, v. 5, p. 375389). In this study we used laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) to compare the trace element signatures of two different coeval microbialites, in this case Renalcis and Rothpletzella from the Devonian of the Canning Basin, Western Australia. The two calcimicrobes can be readily distinguished from each other both petrographically and on the basis of their trace element inventories. For example, in preliminary results Rothpletzella has higher V/La (mean = 0.46; SD = 0.26) and Sn/La (mean = 0.015; SD = 0.00087) ratios than Renalcis (V/La = 0.22; SD = 0.15 and Sn/La = 0.0068; SD = 0.0027) or cement (V/La = 0.016; Sn/La = 0.0044, n=l). The Renalcis and cement data are consistent with previous analyses. Consistent differences in the trace element behaviour of these two calcimicrobes may reflect continued next page.. Australian Earth Sciences Convention 2008
249
250 ABSTRACTS
alpfiabetlcally by symame of pmmntlng author biological differences in the microbial communities responsible for their precipitation. If such biological signatures can be confirmed, they may be applicable to more ancient microbialites providing independent evidence for biogenicity and for distinguishing different microbial communities.
Trace Element Geochemistry of Neoproterozoic Stromatolites: a Tool for Interpreting Accretionary Processes G r e g o r y E. W e b b ^ J o s h u a J. Moulds^ ^Queensland University of Technology, Australia (ge.webb@qut.edu.au)
Brisbane,
Stromatolite accretion reflects two major processes: 1) trapping and binding of detrital sediment; and 2) induction of mineral precipitation. Although trapping and binding is relatively well understood, microbially-induced precipitation of carbonate minerals is probably more important through geologic time. The trace element signature of detritus is readily distinguished from hydrogenous carbonates, but difficulty in distinguishing microbially-induced precipitates from early marine cements is more challenging. Regardless, microbial carbonates take up some trace elements at high concentrations relative to cements. We analysed a stromatolite bioherm from the Neoproterozoic Bitter Springs Formation, Northern Territory using laser ablation-ICP-MS. The bioherm contains three stromatolite morphologies in vertical succession: 1) planar laminae at the base; passing into 2) wavy laminae; which pass into 3) isolated columns. Associated detrital sediment was also analysed. On cross plots of La versus V and Zr, planar laminae plot in the same field as detrital sediment suggesting that they contain abundant clastic detritus, an interpretation supported by insoluble residue studies. Columnar stromatolites plot in a tight, separate field with relatively low V and Zr. They appear to be free of trapped detritus. The morphologically intermediate wavy laminae contain significandy higher La concentrations than the columns, and lower V and Zr concentrations than detritus, although rare analyses overlap the detritus field. They do not represent a simple mixture of columnar laminae and detritus. Hence, the three lamina types show differing trace element characteristics. Columns may be volumetrically dominated by the growth phase of hydrogenous calcite following microbially-induced nucleation. La enrichment in the wavy laminae may reflect more influence of the microbial biofilm (more abundant nucleation) relative to crystal growth. Thus, they may have a more concentrated microbial trace element signature than the columns. Regardless, the different lamina types show major differences in trapping and binding behaviour. Australian Earth Sciences Convention 2008
Tectonic/Volcanic Control On Salinisation of Bet Bet Creek, Central Victoria. Webb. John A..^ Coady, K.,^ Reid, M.^ and Fawcett, J.^ ^Environmental Geoscience, La Trobe University, Victoria 3086 (John. Webb@latrobe.edu.au;) ^Future Farming Systems Research Division Department of Primary Industries, FO Box 3100, Bendigo Delivery Centre VIC 3554 (mark. reid@dpi. vic.gov. au; Jon.Fawcett@dpi.vic.gov.au) The Upper Bet Bet catchment in central Victoria is a targeted priority salinity area, as it exports extremely high levels of salt (-1.5 tonnes per hectare per year). In the mid-Tertiary the drainage system across much of central Victoria was disrupted by ENE-trending faults. One of these intersected the ancestral Bet Bet Creek, which flowed northnorthwest. Uplift of the northern side of the fault diverted the lower (northern) part of the creek east into the Madame Hopkins paleovalley; the upper Bet Bet Creek maintained its original course. In the Pliocene-Pleistocene, Newer Volcanics basalt flows filled the Madame Hopkins paleovalley. A basalt tongue flowed a short distance up into the upper Bet Bet valley, damming the creek and filling the paleovalley with 15-20 m of mostly fine-grained alluvial and swamp deposits. Bet Bet Creek was diverted around the western edge of the basalt constriction, but the valley has never significantly incised. The relatively low permeability sediment fill of the upper Bet Bet valley, including thick ligneous clay, constrained the water table to very shallow depths across the lower parts of the catchment. Preserved wetland soils show that water tables have always been high. Evapotranspiration above the shallow watertable resulted in the accumulation of very high salt concentrations in the soil and groundwater. Land clearing has caused up to 3 m of incision in the drainage lines but has not caused a significant fall in the water table, which is held at high levels by the low permeability alluvial fill of the catchment. Thus the primary cause of salinity in the catchment, the high water table, was not caused by clearing of trees but results from the landscape evolution, whereby fault diversion of the stream allowed the basalt flows to dam the creek. Bet Bet Creek is unique in its tectonic/volcanic history and the way that this is directly responsible for its extreme salinisation.
ABSTRACTS 251 atphabeticafly by surname of presenting author
Drowned Reefs in The Great Barrier Reef And Hawaii: a New Era in lODP Coral Reef Drilling Jody M. Webster^ ^School of Earth Sciences, James Cook University, Townsville, Qld 4811, Australia The success of the recent lODP Tahiti Sea Level Expedition 310 has paved the way for a new era in shallow water carbonate drilling and research. This paper will summarize the scientific rationale and progress towards lODP drilling of drowned reefs off the GBR and Hawaii. The site survey has now been completed for the GBR with EM300 bathymetry, seismic, AUV imaging and rock dredging data collected on a 2007 RV Southern Surveyor cruise. Similar to the Tahiti expedition, the scientific objectives of the GBR drilling are three fold; (1) to establish the nature of sea level rise since the last ice age about 20 ka; (2) reconstruct associated changes in sea surface temperature and salinity; and (3) determine how the GBR responded to these changes in terms of geometry, composition and community structure. Scientific drilhng in the GBR will provide not only an important comparison with the Tahiti record but also a unique archive of Western Pacific sea level variabihty, climate change and reef evolution. Observational and numerical modehng data from the drowned Hawaiian reefs indicate that the internal stratigraphy and tops of the reefs are highly sensitive to sea-level and climate changes. Furthermore, as a direct result of Hawaii's rapid but constant subsidence, thick (100-200 m) expanded reef sequences are preserved. These reefs span important periods in Earth climate history that are either not available or are highly condensed, due to a lack of accommodation space and/or unfavorable shelf morphology, on stable (eg., GBR, Tahiti) or uplifted margins (eg., PNG, Barbados). The Hawaiian reefs grew throughout (albeit episodically) the majority of the last six glacial cycles. Therefore, scientific drilling through these reefs will generate a new record of sea-level and associated climate variability during several controversial and poorly understood periods over the last 500 kyr.
Sediment Flux and Composition Changes in Canyons on a Carbonate-Siliciclastic Margin: Evidence From Turbidite Deposits Along The Great Barrier Reef Margin. Webster, J. Ludman, D., Wust, R., Beaman, R., Renema, W, Moss, P. Jacobsen, G. ^James Cook University The shelf edge and slope of the Great Barrier Reef is heavily incised by submarine canyons which terminate in the Queensland Trough. Traditionally, sedimentation on the margin has been investigated within the framework of idealized siliciclastic or carbonate systems, depending on whether rivers or shallow marine carbonate producers dominate supply. The widely accepted paradigm ('reciprocal' sedimentation) states that sea-level strongly influences shelf, slope and basin sedimentation, with siliciclastics dominating lowstand periods and carbonates dominating transgressions/highstands. However, recent work (e.g., Dunbar and Dickens, 2003) on cores from the slope and basin has challenged this view. These workers argue that accumulation of both siliciclastic and carbonate sediments varies in phase, with the highest rates observed during transgressions, lowest rates during lowstands and moderate sedimentation during highstands. Irrespective of which model is correct, exactly how the sediment (carbonate or siliciclastic) moves from the shelf to the basin, and the role of submarine canyons in this process is not understood. We address this problem directly by investigating sedimentation in the canyons bordering the GBR. Combining new multibeam bathymetry and seismic data with x-radiograph, magnetic susceptibihty, insitu reflectance spectroscopy, grain size, CNS, petrologic, pollen and '"^C AMS analyses of canyon cores off Cooktown and Cairns, we aim to establish the source, timing and frequency of turbidite events deposited in the canyons over the last glacial to interglacial cycle, thereby testing the competing models. Our preliminary data confirm that: (1) the canyons record a distinct sedimentary shift from siliciclastic turbidites to calciturbidites; (2) the siliciclastic turbidites were deposited before 28 ka - providing strong support for the "reciprocal" model of margin sedimentation; and (3) the canyons have been active throughout the last deglaciation and into the late Holocene.
Australian Earth Sciences Convention 2008
252 ABSTRACTS alphabetlcaily by surname of presenting author
Higher Order Neighbour Statistics of Martian North Polar Crescentic Dune Fields.
Attenuation of High-Strain Zones in the Wyangala Granite, Lachlan Fold Belt, NSW, Australia
A. J. W h e e l e r \ M.A. Bishop^'^
Mr. Lloyd White^' ^ Dr. Paul Lennox^
^ School of Natural and Built Environments, University of South Australia, Adelaide, SA, 5095 (andrew. wheeler@postgrads. unisa. edu.au) ^ Planetary Science Institute, 1700 East Fort Lowell Road, Tucson, AZ 85719, USA (bishop@psi.edu)
^ Current Address: Geoscience Australia, Canberra, Australia (lloyd_white @ hotmail. com) ^ School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia (p.lennox@unsw.edu.au)
Dune fields are self-organizing and correspond to environmental changes in climate, sediment availability and particle transport. The geographical self-organization of dune fields using spatial statistical techniques has been little explored and may offer significant insight into the evolution of aeolian systems. Nearest Neighbour Analysis (NNA) is founded upon the concept of complete spatial randomness through analysis of the R-statistic. Firstorder NN statistics identify a particular pattern (clustered, random, dispersed) at the local scale, while higher order statistics are capable of discerning spatial patterns at regional or global scales. Such spatial characterization can imply an understanding about underlying geomorphic processes. Interpretation of the R-statistic indicates several major findings have been determined for the spatial characterization of Martian North Polar crescentic dunes. 1. The nearest neighbour R-statistic expresses the most significant degree of dispersion relative to the R-statistic of all other higher ordered neighbours; 2. Crescentic dunes have a tendency towards increasing spatial randomness as the distance between neighbours increases (i.e. at higher order neighbours); 3. The R-statistic is a geographical signature with which to measure the degree of self-organization in a dune field; 4. An R-statistic of R 1.42 is the geographic signature which represents the greatest degree of dune self-organization measured for a martian high latitude crescentic dune field at this time. In summary, it has been shown that the nearest neighbour distance correlates with those dunes that are most organized and regular in distribution, while higher-order neighbours indicate spatial indices characteristic of lesser organization and pattern regularity. The relationship between location, degree of dispersion and morphology implies that the effects of positive spatial autocorrelation are present.
High-strain zones occur on the eastern margin of the Wyangala Granite and are classified as part of the Wyangala Fault System. The high-strain zones are localised areas of ductile deformation and are not laterally continuous south of Wyangala Dam. The high-strain zones were mapped and classified into components of relative strain intensity on the basis of k-feldspar grain-size reduction, the presence of S-C fabrics and the development and thickness of mylonite zones. The acute angle between S and C fabrics was also used to map strain variation across the field area, however the results obtained from this analysis often conflict with more obvious signs of higher-strain, such as outcrops of ultramylonite. In general, strain intensity increases from west to east, an observation that is also supported by microstructural analyses of samples of the Wyangala Granite across the field area. Net-slip vectors derived from S/C plane intersections and stretching lineations indicate the high-strain zones developed with a component of sinistral strike-slip displacement and a component of west-over-east reverse faulting. The two movement components could have developed as a result of two deformation events, or synchronously during transpression. However it makes more sense kinematically if the two components developed synchronously in a transpressional regime. The region has a complex structural history. The Benambran event led to the formation of a pervasive axial planar cleavage and tight isoclinal north-south trending and doubly plunging folds in the Adaminaby Group. Granite emplacement occurred in the latest Early Silurian and is possibly associated with the oblique opening of the Hill End Trough. East-West shortening in the Tabberabberan event led to the development of S-C foliations and high-strain zones in the Wyangala Granite. Subsequent deformation of the area during the Kanimblan event probably uplifted the region and led to the reactivation of structures.
Australian Earth Sciences Convention 2008
ABSTRACTS 253 alphabetically by surname of presenting author
A Hydrogeologicallandscape framework providing new insights into salinity processes and management approaches.
Evidence for a Massive H2S Release To Surface Waters at the Precambrian Cambrian (PC-C) Boundary From Mo Isotopes.
John Wilford', Jeremy James ^ and Larysa Halas^
Martin Willed Thomas F. Nagler^ Bemd Lehmann^ Stefan Schroeder"^, Jan D. Kramers^
^Cooperative Research Centre for Landscape Environments & Mineral Exploration (CRCLEME), c/o Geo science Australia, PO Box 378, Canberra ACT2601, Australia (john.wilford@ga.gov.au) The hydrologeological-landscape concept provides a new framework for understanding hydrological and sahnity processes, and guide natural resource management actions. Hydrogeological-Landscape units consist of several key components including; lithology, bedrock structure, regolith (including soils) and landforms. These components are defined from both existing and newly acquired data (e.g. geology and soil maps), and modelling techniques. This information is integrated with groundwater and surface water attributes climate and vegetation data to describe different hydrological systems. The components are compiled and aggregated across a range of landscape scales to describe regional and local groundwater processes. Because the regolith has a major influence on groundwater chemistry and flow pathways, a long-term landscape evolution perspective with an emphasis on understanding palaeo- to present-day regolith-landform processes is an important element in the new approach. Several case studies (Adelaide Hills, Bet Bet catchment central Victoria and the Central west catchment in NSW) located in contrasting landscapes within eastern Australia are used to illustrate the approach and show how improved knowledge of surface and groundwater characteristics from both spatial and conceptual perspectives can be used to support management across a range landscape scales. The case study areas show a high degree of variability in the nature and distribution of regolith materials, salt stores and groundwater flow systems that operate over a range of different scales. These characteristics are not unusual but instead, typify many Australian landscapes that have had a protracted weathering and erosional history. In each area detailed nested HL units have been compiled that classify the landscape based on soil/regolith, bedrock (type and structure), landform and salinity characteristics. Broader-scale HL are linked to conceptual hydrological and salinity models, whereas finerscale landform and regolith attributes enable the land manager to target land and creek salinisation in specific parts of the catchment
'Research School of Earth Sciences, Australian National University, Canberra, Australia (martin. wille@and. edu. org) ^ Institute for Geological Sciences, University Bern, Bern, Switzerland (naegler@geo.unibe.ch) Insitute of Mineralogy, University of Clauthal, Clausthal-Zellerfeld, Germany (Lehmann@min.tuclausthal.de) ^ Total E&P, Ave Larribau, F-64018 Pau, France The environmeltal circumstances which have caused the rapid decline in of the soft-body Ediacara fauna at the end of the Precambrian is still a question of debate. Besides several triggers and associated kill mechanism, shallow water euxinia caused by upwelling of euxcinic bottom waters could provide an explanation for this biotic crisis. Here we present Mo isotope signatures in black shales from two sample sets (Ara group, Oman and Yangsee Platform, China) which were deposited at and shortly after the PC-C boundary. At the first view, the overall Mo isotopic signature of the early Cambrian black shales from Oman and China are similar to the signature found in Mesoproterozoic shales (Arnold et al. 2004). Canfield (1998) proposed that the Paleoproterozoic and Mesoproterozoic ocean was strongly chemically stratified with sulfidic deep deep waters and modestly oxygenated surface waters. Our new early Cambrian data support the idea that this stratification might have been a common situation until the end of the Proterozoic. On an closer inspection, a transient Mo isotopic signal following immediately after the PC-C boundary in both sample sets indicates a short but intense global non-steady state situation. Combined with the extreme Mo enrichment, found in the Chinese sulfide marker bed at the PC-C boundary, this signal can not be explained with recent Mo scavenging mechanism known from recent oceans. We put forward the working hypothesis of an upwelling of euxinic bottom water masses of an chemically stratified ocean as explanation for this Mo anomalies. This scenario not only explains the transient isotopic signal and the metal enrichment found at the PC-C boundary in several localities, it can also be responsible for the sudden extinction of the Ediacarian fauna caused by H2S poisoning.
Australian Earth Sciences Convention 2008
254 ABSTRACTS alphabetically by surname of presenting author
Advances in SHRIMP Zircon U-Pb Geochronology and Oxygen Isotopic Analysis Ian S. Williams ^ Ryan B. Ickert^ Joe M. Hiess^ Peter Holden\ Bruce W. Chappelf ^Research School of Earth Sciences, The Australian National University, Canberra, ACT, 0200 (ian.williams@anu.edu.au) ^School of Earth and Environmental Sciences, University of Wollongong, NSW, 2522 Zircon is well known as a robust mineral for UPb geochronology, but it is also an excellent host for other isotopic systems (O, Hf). Zircon crystals are commonly zoned, each zone preserving a record of the local environment in which that zone crystallised. Zircon precipitated from a magma records part of the isotopic evolution of that magma, commonly even if the host rock is subsequently altered. Zircon U-Pb geochronology using high resolution ion microprobes is a long-established technique, but only in the last few years have methods been developed for using ion probes to measure oxygen isotopic compositions in situ with high (sub-permille) precision. Until recently such work could only be done using Cameca 1270/1280 ion probes outside Australia. Following upgrades to the SHRIMP II ion probe and the development of new analytical procedures, this capability is now available in Australia. SHRIMP developments include installation of a Cs primary ion source and an electron gun, and implementation of analysis by multiple collector. These permit high precision analysis of oxygen isotopes in non-conducting minerals, but do not alone guarantee high accuracy. The latter has been achieved by other methods, including local nulling of the Earth's magnetic field, changes in mount design, and the development of procedures to stabilise instrumental isotopic fractionation. These changes have also improved the accuracy of U-Pb age measurements. The benefits of these developments will be discussed using work on the granites of the Bega Batholith (SE Australia) as the main example of what can now be achieved.
Transfer of Research Initiatives into Practice - How Effectively Are New Concepts Driving Exploration Outcomes? Peter Williams ^ Paul Roberts^
' SRK Consulting, 10 Richardson St, West Perth (pwilliams @ srk. com.au) ^ CSIRO Exploration and Mining, 26 Dick Perry Avenue, Kensington (paul.a.roberts@csiro.au) The uptake of the outcomes of research Australian Earth Sciences Convention 2008
program by exploration practitioners varies considerably. Where new technologies can be transformed into practical techniques that are provided as a contract or a service, uptake has been excellent. However, in the more conceptual areas, and in areas where outcomes require significant investment of either a capital or intellectual nature, the uptake has been quite sporadic. In this contribution, we examine some of the fundamental difficulties in transferring expertise that is potentially critical to the discovery rate for new deposits. As has been demonstrated by more than a decade of research in successive CRC's, an understanding of the geometry of ore forming systems in 4D is a critical aspect in both explaining the location of ore deposits and searching for more. However, despite the vast amount of research done over those years, almost invariably, this exploration is conducted using traditional 2D geochemical techniques, generally with an overlay of electrical geophysics (EM/IP) or potential field targeting through modelling. There is still a poor integration of advanced interpretation skills to control the 2D targeting, even before 3D is considered. Access to the research also remains a problem, although there have been steps to advance facilitation of knowledge transfer through the more recent pmd*CRC innovations. However, models for funding of research as practiced in Australia seem to favour larger companies. Also, the consulting industry is in a strong position to provide leveraged delivery of conceptual research outcomes, but is generally not in a position of access to or ownership of outcomes that could be more widely disseminated. There is some evidence for declining discovery rates over the past few years, despite accelerated exploration expenditure. In this presentation, we review if impediments to implementation of research outcomes may be one of the factors contributing to this apparent decline.
Molecular and Isotopic Evidence For A Microbial Response To The TriassicJurassic Mass Extinction Kenneth H. Williford^ Peter D. Ward^'^ Julien Forief, David Kring^, Valerie Schwab^ Stuart Wakeham^ Julian Sachs^ Kliti Grice^ ^ Stable Isotope and Molecular Biogeochemistry Group, Curtin University of Technology, GPO Box U1987, Perth, WA 6845, Australia ^ Department of Biology, University of Washington, Seattle, WA 98195, USA ^ Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA ^ Lunar and Planetary Institute, 3600 Bay Area Blvd., Houston, TX 77058, USA ^ School of Oceanography, University of Washington, Seattle, WA 98195, USA ^ Skidaway Institute of Oceanography, Savannah, GA 31401, USA
ABSTRACTS alphabetically by surname of presenting author
An extended record of stable organic carbon isotopes (? ^^Corg) from the Triassic-Jurassic (Tr-J) R.. boundary section at Kennecott Point, Queen Charlotte rec Islands (QCI), British Columbia, Canada shows a long Qi term trend of isotopic lightening attributed to an Pa increase in atmospheric CO^ due to volcanism 24 associated with the opening of the Atlantic Ocean, including the Central Atlantic Magmatic Province (CAMP). This trend is interrupted by a negative excursion of 2 % o (Ward et al, 2 0 0 1 ; 2 0 0 4 ) and a newly discovered 5%o positive excursion (Williford et al, 2 0 0 7 ) . A record of stable organic and pyrite sulfur isotopes (? ^"^Sorg+pyrite) from this section shows a large positive excursion coincident with the excursion in carbon. ? ^"^Sorg+pynte values shift from -30%o to 20%o over 3 m of section, suggesting that isotopic fractionation associated with bacterial sulfate reduction (BSR) was reduced or eliminated due to a rapid drawdown of seawater sulfate via increased BSR, increased evaporite flux, or a decoupling of the water column and sediments due to increased turbiditic deposition. A record of lipid biomarkers from the QCI section shows that organic material is of low to moderate thermal maturity and highly biodegraded. Abundant C29 steranes are indicative of a significant terrestrial component. Samples from strata containing the positive excursion in ? Corg and ? Soi-g+pynte are much less biodegraded and contain few hopanes and steranes but abundant high molecular weight ^-alkanes. A spike in C30 hopane abundance just before the Tr-J boundary, coincident with the negative excursion in ? ^^Corg and a major radiolarian extinction (Carter and Hori, 2005), suggests a decline in net primary production as bacterial heterotrophy outstripped primary productivity in the wake of the Tr-J event, contributing to the negative excursion in ? ^^Corg. These findings demonstrate that the Tr-J extinction, and the recovery that followed, were accompanied by major perturbations in carbon and sulfur cycling. A microbial response to boundary events is evident. Processes associated with the early rifting of the Pangean supercontinent including sea level change, evaporite deposition and CAMP volcanism are the most likely primary causes for the global biogeochemical perturbations, and volcanically induced warming remains the most likely cause for the Tr-J extinctions. References Carter, E. and Hori, R., 2005. Global correlation of the radiolarian faunal change across the TriassicJurassic boundary. Canadian Journal of Earth Sciences 42(5): 777-790. Ward, P. D., Garrison, G. H., Haggart, J. W., Kring, D. A., and Beattie, M. J., 2004. Isotopic evidence bearing on Late Triassic extinction events. Queen Charlotte Islands, British Columbia, and implications for the duration and cause of the Triassic/Jurassic mass extinction. Earth and Planetary Science Letters 224: 589-600. Ward, P. D., Haggart, J. W., Carter, E. S., Wilbur, D., Tipper, H. W., and Evans, T., 2001. Sudden productivity collapse associated with the Triassic— Jurassic boundary mass extinction. Science 292: 1148-
1151.
Williford, K., Ward, P., Garrison, G., and Buick, R., 2007. An extended stable organic carbon isotope record across the Triassic-Jurassic boundary in the Queen Charlotte Islands, British Columbia, Canada. Palaeogeography Palaeoclimatology Palaeoecology 244(1-4): 290-296.
Central Victorian Deep Crustal Reflection Seismic Survey 2006: Implications for Mineralisation. C.E. Willman^ RJ. Korsch^ D.H. Moore\ TJ. Rawling^ R.A. Cayley^ ^ GeoScience Victoria, Department of Primary Industries, GPO Box 4440, Melbourne VIC 3001 (Clive. Willman@dpi. vic.gov. au) pmd^CRC, Geoscience Australia, GPO Box 378, Canberra ACT2601 (Russell.Korsch@ga.gov.au) ^ pmd'^CRC, GeoScience Victoria, Department of Primary Industries, GPO Box 4440, Melbourne VIC 3001 The -400 km long Central Victorian deep crustal reflection seismic survey was carried out in 2006 as a collaborative project between the ;?m(i*CRC, Geoscience Australia, the Victorian Government, Ballarat Goldfields NL, Gold Fields Australasia Pty Ltd and Perseverance Corporation Ltd, and using the facilities of ANSIR. The survey aimed to reveal the crustal architecture of Palaeozoic rocks under one of the most productive gold provinces in Australia. The survey has provided insights into possible fluid pathways during Early Palaeozoic mineralisation. The bilateral distribution of historic gold production in the Stawell and Bendigo zones suggests that the transport of hydrothermal orefluids was strongly controlled by the overall Vshaped crustal architecture of the two zones. Greenstone-associated gold deposits are located in the hangingwalls of a few major boundary faults that have exhumed the normally deeply-buried volcanic rocks. The best example is the Stawell mine in the hangingwall of the Moyston Fault. This major east-dipping fault cuts through the entire crust to the Moho, close to the western margin of the Lachlan Orogen. Sediment-hosted gold deposits have produced most of Victoria's gold. Deposit clusters are generally in the hangingwalls of major unmineralised internal faults within the Stawell and Bendigo zones. These faults are mainly west-dipping listric faults that penetrate the seismically highly reflective lower crust. Most gold production has come from a section of the Bendigo Zone where these listric faults penetrate to >20 km into a region interpreted as mostly mafic volcanic rocks. The Heathcote Fault Zone forms the eastern boundary to all Early Silurian mineralisation—it is a major fault zone that extends to at least 20 km depth and possibly to the Moho. All Late Devonian gold deposits in the eastern Bendigo Zone and Melbourne Zone are underlain by horizontally layered lower crust, the Selwyn Block.
Australian Earth Sciences Convention 2008
255
256 ABSTRACTS alphabeticaily by surname of presenting author
Technology and Integration: Improving Exploration Success - the Australian Mineral Fields Philosophy. Marcus Willson^ Carl Young\ Greg Hall\ Scott Halley^ 1 Australian Mineral Fields Ltd, Suite 18, 44 Parliament Place, West Perth, 6005 (mwillson @ australianmf. com, cyoung @ australianmf. com, ghall @ australianmf. com) 2 Mineral Mapping Pty Ltd , 24 Webb Street, Rossmoyne, W.A. 6148 (minmap@westnet.com.au) Modern exploration is about the discovery of blind or buried deposits that traditional exploration techniques are unlikely to detect. In order to be successful in this environment, maximum value must be derived from all data. Traditional exploration has focussed on ore deposit discovery by the use of direct mineralisation indicators (surface geochemistry) and indirect mineralisation indicators (geophysics). More drilUng is a cost prohibitive solution. A single drill hole must represent a square kilometre, not 100m2. Significant value is often destroyed in the initial stages of exploration either through overdrilling of poorly understood near-surface anomalism, or failing to recognise an ore system due to absence of grade. Modern exploration for blind ore deposits under deep cover must focus on the definition of the mineral system, rather than ore intersection only. Techniques such as hydrogeochemistry and primary lithogeochemistry and hyperspectral mineral mapping, are the new methods of detecting the mineral system and help to increase the probability of exploration success by defining the exploration 'Stadium'. This can be achieved given that the footprint of ore-related systems is generally 1 to 2 orders of magnitude larger than the ore body. Once within the 'Stadium', quality geology and further integration can decrease discovery lead-time and exploration costs. The application of some of these non-traditional exploration techniques is equally applicable to greenfield exploration programs and brownfield project evaluations
Cenozoic Carbonate Response to Climatic Change Due to a TectonicInduced Latitudinal Shift Movra EJ. Wilson^ Ben Kilhams^ Peter Lunt^ ^ Dept. of Applied Geology, Curtin University, Perth, WAustralia (m.wilson@curtin.edu.au) ^ School of Environmental Sciences, University of East Anglia, Norwich, UK ^ Murphy Oil Sarawak, Petronas Twin Towers, Kuala Lumpur, Malaysia Australian Earth Sciences Convention 2008
The research hypothesis being tested is that the limestones of Christmas Island (Indian Ocean) will preserve a unique record of how reefs respond to climatic change due to tectonic induced latitudinal change. Lying on the leading edge of the Australian tectonic plate, Christmas Island has moved northwards from temperate to tropical latitudes over the last 50 million years due to plate tectonic drift. Limestones originally formed in shallow marine, reef-related environments are excellent indicators of environmental and climatic change. Those now uplifted on Christmas Island formed over much of the last 50 million years during this phase of northward drift. Initial results reveal changes in carbonateproducing biota, platform structure and diagenesis consistent with the inferred climatic warming related to plate tectonic drift. Geochemical results from stable isotopic analysis are also suggestive of warming, although there is a strong meteoric overprint. The importance of this research is in providing an insight into how marine communities respond to climatic warming. This is pertinent to understanding the likely response of temperate marine ecosystems to present day anthropogenicallyinduced global warming. The study therefore has implications for how the carbonates of the NW Shelf have changed over the Cenozoic, and how the reefs of Australia may respond to future global warming.
South Jimblebar,Newman - an integrated team approach to an iron ore discovery. Steve Wilson\ Brad Baker\ Matt Crowe\ Asmita Mahanta^ ^REG, Technical Services South Jimblebar is located on the south eastern margin of the Hamersley basin, 50km east of Newman, and comprises approximately 22km of east-west striking Marra Mamba Iron Formation. Surface outcrop presents difficulties in stratigraphic interpretation and mineralisation is largely concealed by recent colluvial deposits and regolith. The deposit is hosted within a north-dipping deformed sequence with enrichment developed within all three members of the Marra Mamba Iron Formation and the West Angela Member of the Wittenoom Formation. Mineralisation is dominantly martite-goethite with minor occurrences of ochreous goethite, in contrast to historically mined Marra Mamba deposits in Newman. Preliminary investigations show differences in the stratigraphy compared to that documented elsewhere within the Hamersley Basin. The discovery and ongoing rapid assessment of this concealed deposit is the result of the following key steps: - Reinterpretation of the stratigraphy of outcropping Marra Mamba Iron Formation through surface geological mapping.
ABSTRACTS alphabetically by surname of presenting author
- Structural interpretation ot the geometry and thickness of potential host stratigraphy. - Interpretation of high resolution gravity and magnetic data to identify zones of potential iron ore mineralisation within the overall Marra Mamba sequence. - Drill testing of targets generated from the above three steps.
Integrating remote-sensing with airborne electromagnetics for vegetation and crop health along the River Murray Corridor Vanessa Wong\ Ken Lawrie^ Medhavy Thankappan^ and Larysa Halas^ ^ Geoscience Australia, GPO Box 378, ACT 2601, Australia (Vanessa.wong@ga.gov.au) The Murray River floodplain is host to unique ecosystems, protected in a series of National Parks, Ramsar-listed wedands, and State forests. The Murray River itself sustains many regional communides by providing water supplies for widespread irrigation largely adjacent to the floodplain, and for town water supplies. There has been significant degradation of biodiversity assets on the floodplain, with 70% degradation in some Icon sites. This is attributed both to the effects of increasing river regulation and a significant decline in river levels and the frequency and magnitude of flood events, and to increasing sahnisation of groundwaters. It is thought that continued drought and salt accumulation pose significant additional risks to biodiversity assets in the Murray floodplain. Previous approaches to assessing vegetation and crop dynamics have largely focussed on responses to rainfall and temperature, with only a brief consideration given to below-ground processes. However, in groundwater dependent ecosystems, such as those found on the Murray River floodplain, vegetation and crop dynamics are also likely to be driven by changes to groundwater processes. Previously, a range of electromagnetics (EM) techniques have been used to successfully map aquifer and groundwater systems, identify gaining and losing stream components and understand the spatial patterns of salt accumulation in many catchments including the Murray River floodplain. This study uses a time-series analysis of satellite imagery (SPOT, Landsat and MODIS) integrated with AEM and other hydrogeological data to assess vegetation health on the Murray River floodplain, and crop yields in parts of the floodplain and in bordering terrace and upland landscapes. This approach maps changes in temporal and spatial patterns of key elements of the biophysical system linked to vegetation health The approach provides a framework for examining the drivers for fluctuations in seasonal and inter-annual time scales process-based studies involving soil-water, regolithwater, and plant-water interactions at. As a result.
the primary drivers for land cover and vegetation health change can be determined, with new groundwater resources delineated and improved hydrogeological frameworks developed for management strategies on the floodplain.
Auscope: Australian Earth Science Research Information Infrastructure Dr Robert Woodcock^ Dr Simon Cox\ Mr Ryan Fraser\ Dr Lesley Wyborn^ ^CSIRO Exploration and Mining, 26 Dick Perry Ave, Kensington, WA 6151, Australia (Robert. Woodcock@csiro.au, Simon. Cox@csiro.au, Ryan. Eraser @ csiro. au) ^Geoscience Australia, GPO Box 378, CANBERRA ACT2601, Australia (Lesley.Wyborn@ga.gov.au) In 2006 the Australian Government announced a new funding inidative, the National Collaborative Research Infrastructure Strategy (NCRIS). NCRIS aims to provide Australian researchers with access to major research facilities, supporting infrastructure and networks necessary for world-class research. As a component of this strategy, $42.8 million was allocated to the Australian earth science research community to build an integrated national geoscience infrastructure system called AuScope. Auscope will provide a number of infrastructure components to assist in understanding the structure and evolution of the Australian continent. These include the acquisition of subsurface earth imaging and earth composition and age analysis, a virtual drill core library, geological process simulation, and a high resolution geospatial reference framework. To draw together information from these new initiatives and from other existing sources in academia, industry and government, AuScope is developing a world-leading geoinformatics network. The Auscope Data Grid will use open geospatial standards to allow real time access to data, information and knowledge stored in distributed repositories. The Data Grid will be built on 'endtoend' science principles whereby there will be access to the highly processed information and knowledge as well as the original raw data and the processing programs used to generate the results. The key to linking resources on the AuScope infrastructure will be web service based access to the geoscience information holdings and computational services using common service interface and information models, including the emerging international standard for geoscience information, GeoSciML. GeoSciML is being developed through the Interoperability Working Group of the Commission for the Management and Application of Geoscience Information (CGI), a commission of the International Union of Geological Sciences (lUGS). Australian Earth Sciences Convention 2008
257
258 ABSTRACTS alphabetically by surname
of presenting author
An Organogenic Model for Carbon Sequestration David T Wright^ ^Department of Geology, University of Leicester, University Road, Leicester LEI 7RH, UK (dtwl@le.ac.uk) Increasing CO2 emissions are causing climate change and ocean acidification with predicted severe consequences for ecosystems and for human society. A portfoho of strategies are being sought to mitigate emissions, including the storage of CO2 within different parts of the geosphere. Although capture of CO2 from large point sources is a practical option, most anthropogenic releases of CO2 come from smaller, more widely-distributed sources that do not lend themselves to current capture technologies. Investigating methodologies that can remove CO2 from the atmosphere may therefore play a crucial role in reducing overall anthropogenic CO2 build up. Under the terms of the Kyoto Protocol (now ratified by a majority of countries), signatories can meet part of their obligations to reduce greenhouse gas emissions from fossil fuel consumption by increasing land carbon sinks. However, there are serious concerns about the permanence of current carbon sinks (typically involving afforestation), and the accuracy with which carbon sequestration can be quantified and verified. A novel organogenic model for carbon sequestration in dolomite, based on natural systems and proven in laboratory experiments, is offered as a long-term option for large-scale carbon management. The model employs microbially-induced mineralisation with the potential for significant sequestration of atmospheric carbon and can satisfy the Kyoto criteria for permanence, quantification, verification and additionality. The technique uniquely provides a lowenergy technological solution for significantly reducing atmospheric CO2 levels by mineral sequestration. It can be located where land is unsuitable for agriculture, and requires low levels of capital investment and maintenance costs. Model projections indicate annual sequestration of some 45 MT of atmospheric carbon with sufficient engineered systems, while initial rates of dolomite precipitation achieved in the laboratory indicate that this can be increased by at least an order of magnitude.
rth Sciences Convention 2008
Multiphase Palaeochannel Development on the Great Barrier Reef Shelf, Australia Raphael Wust\ Jody Webster \ Rob Beaman^ ^School of Earth and Environmental Sciences, James Cook University, Townsville, 4811, QLD, Australia (raphael. wust@jcu. edu. au) Multiple paleochannel systems across the Great Barrier Reef Shelf have long been recognised and several studies conducted that showed channel width and depth and have been assigned to modern fluvial systems. In most cases, simple cross-section have been presented and interpreted to be the result of the sea level lowstand during the last glacial maximum. This despite the fact that channel tracking, for example of the Paleo-Burdekin River Channel, has been proven to be difficult because of several "branches" that apparently developed in the mid and outer shelf area. Here we present a high-resolution analysis of a short section (1 km x 1 km) of the Paleo-Burdekin River system in the mid shelf area that illustrates that both erosional as well as infilling structures are complex and are the result of multi-phase channel development rather than from the last glacial lowstand only. This is in contrast to most published work but in agreement with studies from the Fraser River Paleochannel system. The analysis shows that several erosional features can be depicted based on seismic analysis. The sedimentary structures also demonstrate that the infilling of the channel features was complex. In addition, we show new evidence of the shelf edge Paleo-Burdekin River system that exceeded well our expectations of magnitude of the "delta" system. The size illustrates that during the lowstand, significant erosion and deposition must have occurred along the shelf slope as a result of the River system discarding directly onto the shelf slope.
ABSTRACTS alphabetically by surnatne of presenting author
MWP-IA and its implication for the moisture regime change over Borneo evidence from peat archives Raphael Wust\ Sander van der Kaars^, Geoff Hope^ Geraldine Jacobsen"^, Andrew Smith^ School of Earth and Environmental Sciences, James Cook University, Townsville, 4811, QLD, Australia raphaeL wust@ jcu. edu.an
Geochemical Evidence for Oxygenated Oceans 3.46 Ga ago: REE Geochemistry of the Marble Bar Chert Recovered by the Archean Biosphere Drilling Project (ABDP) Kosei E. Yamaguchi^ Yasuhiro Kato^, Kentaro Nakamura^, Katsuhiko Suzuki^, Yumiko Watanabe"^, Munetomo Nedachi^, Hiroshi Ohmoto"^
2
Department of Palynology and Climate Dynamics, Alhrecht-von-Haller-Institute for Plant Sciences, University of Gottingen, Untere Karspiile 2, D37073 Gottingen, Germany ^Department of Archaeology and Natural History, Australian National University, Canberra, Australia ^Australian Nuclear Sciences and Technology Organisation, Lucas Heights, Menai, Sydney, Australia We investigated a peatland in central Kalimantan, Borneo, that showed that peatland evolution in SE-Asia occurred throughout the late Pleistocene but was mainly absent during the LGM when conditions may have been drier and more seasonal. Several peat deposits indicate though that shortly after Meltwater Pulse-1A (-14,000 years ago), peat accumulation commenced and peatlands expanded during the following few thousand years, through to the early Holocene. Although most peat deposits that actively accumulated ruing that period, the central Kalimantan deposits are the only lowland peat domes that started shortly after MWP-IA. This is unique as peat formation and accumulation started well before sea level transgression flooded the Sunda Shelf and that peat accumulation was maximal with accumulation rates ~2-3 mm/yr. This peat record is part of the many large peat domes that exist in this part of Borneo. The deposits indicate that rapid changes in moisture regimes must have occurred during that time associated with changes in sea surface temperatures (as provided by planktonic foraminifera records). This is the first peat archive from lowland Indonesia that illustrates that peat accumulation was possible even with a sea level well below its present position and therefore entirely driven by increased precipitation. The hypothesis of moisture regime changes is also supported by speleothem records from Borneo. Weaker seasonality and/or more precipitation due to a strengthening of the monsoon systems (stronger trade winds) are the most likely explanations.
^Precambrian Ecosystem Lab, Extremobiosphere Research Centre, JAMSTEC (kosei@jamstec.go.jp) and NASA Astrobiology Institute (NAI) ^Dept. Earth System Eng., Univ. Tokyo, and NAI ^Inst.forRes. Earth Evolution (lEREE), JAMSTEC ^Dept. Geosciences and Astrobiology Res. Ctr., Penn State Univ., and NAI ^Dept. Phys. Kagoshima Univ. and NAI Drillcore samples of the -3.46 Ga Marble Bar Chert (MBC), Western Australia, were recovered by the Archean Biosphere Drilling Project (ABDP). In order to constrain geochemical environments for deposition of the chert/jasper beds, a full spectrum of elemental analyses were performed on -140 bulkrock banded cherts from the drillhole ABDP#1 (50~200m depth). The cherts apparently lack sedimentological features indicating shallow-water deposition. We have found that, compared to clastic sediment-containing impure cherts, the leastcontaminated cherts (jasper) possess higher and variable atomic Y/Ho ratios (55-120 vs. -60), higher Fe203/Ti02 ratios (>100 vs. <100), prominent positive Eu anomalies (Eu/Eu* up to - 2 vs. ~1), and modestly negative Ce anomalies (Ce/Ce* down to -0.8 vs. -1.0). Since these characteristics were most likely created during, rather than after, deposition of the sediments, they likely reflect the chemistry of seawater (or hydrothermal fluids) 3.46 Ga ago. Fractionations of Y/Ho ratios are caused by different affinity of those elements for Fe(oxy)hydroxides surface. Y/Ho ratios are typically - 5 0 in normal igneous and sedimentary rocks, but are increased to >90 in modern oxygenated seawater. Therefore, our findings of similarly high but variable Y/Ho ratios for the MBC suggest that the deep oceans were at least locally oxygenated to allow significant Y/Ho fractionation accompanying with Fe-(oxy)hydroxides precipitation. Such precipitates were formed by mixing of Fe^'^-rich submarine hydrothermal fluids (reflected in Eu anomalies) and 02-rich deep seawater (reflected in Ce anomalies).
Australian Earth Sciences Convention 2008
259
260 ABSTRACTS alphabetically by surnanne of presenting author
Subsurface alteration associated with actively forming seafloor massive sulfide mineralisation in the Brothers Caldera, Kermadec Arc, New Zealand Christopher J Yeats\ Melissa Quigley^ ^CSIRO Exploration and Mining, PO Box 1130, Bentley WA 6102, Australia (chris.yeats@csiro.au) The Kermadec 2005 Expedition to the Brothers Caldera in New Zealand in December 2005 was the first attempt to drill seafloor massive sulfide mineralisation for commercial purposes. Exploration centred on two areas on the northwestern caldera wall (Zones A and B), with a final hole drilled into the summit of a dacitic resurgent cone (Zone C) which rises to 1250 metres below sea level (mbsl) from the southern caldera floor. At Zone A, ~1450mbsl, mounds and spires of Fe-Mn-Si oxyhydroxide are actively precipitating from low temperature oxidised fluids ascending through the volcanic rocks of the caldera rim and overlying volcaniclastic sediments. Subsurface alteration is muted and is limited to localised development of Ee-oxyhydroxides, nontronitic and magnesian clays and opaline silica within the glassy volcanic grit. These results are consistent with low temperature («100°C), near neutral pH hydrothermal activity. At ~1650mbsl, the sulfide chimney fields of Zone B are underlain by pale grey altered material dominated by quartz and muscovite/illite, with minor kaolinite and chlorite, locally overprinted by less-widespread greenish intervals that contain significant chlorite and muscovite/illite, with minor quartz and kaolinite. The pervasive quartz-illite(pyrite) alteration is controlled by primary volcanic textures, principally perlitic fracture. The presence of quartz as an alteration phase at or near-surface within Zone B requires widespread high temperature (>150°C) alteration close to the seafloor, or exhumation of a deeper portion of the alteration system. Chlorite is commonly observed in quartz veins and with quartz in amygdales, implying a temporal relationship between the chloritic alteration event and the quartz veining. Anhydrite-rich veins typically contain traces of base metal sulfides, as well as pyrite, indicating a direct link between these veins and current seafloor hydrothermal activity. However, it is not clear whether the quartz- and anhydrite-dominant veins are related. Altered rock from Zone C has a markedly different mineralogy to the material from Zones A and B, with an advanced argillic alteration assemblage featuring native sulphur, cristobalite and natroalunite as the dominant species, implying low pH, most probably magmatically derived, hydrothermal fluids. The advanced argillic alteration assemblage drilled in Zone C is similar to that seen at the Solwara 1 field (formerly Suzette) in the
Eastern Manus Basin and the alteration associated with most terrestrial high sulfidation epithermal copper-gold deposits, suggesting that this area is worthy of further exploration.
Numerical Modelling of Strain Localisation in the Laverton Region, Western Australia Y. Zhang^ P.M. Schaubs\ P.A. Henson^ K. Czarnota^ A. Ord\ H.A. Sheldon^ & R.S. Blewett^ ^prnd'^CRC, CSIRO Exploration & Mining, PO Box 1130, Bentley, WA 6102 (Yanhua.Zhang@csiro.au) ^pmd'^CRC,Geoscience Australia, GPO Box 378, Canberra 2601 (Paul. Henson @ga.gov. au) The Laverton region in Western Australia is richly endowed with Au mineralization (e.g. Sunrise Dam and Wallaby deposits). Extensive work has been carried out to understand the key regional deformation events and their relationship to Au mineralisation. These studies suggested that Au mineralisation was influenced by major deeptapping faults, dome structures, and multiple deformation events with different far-field stress orientations. Variation in far-field stress orientation activated structures of different orientation at differing stages in the history, thus controlling the timing and location of mineralisation. This study uses 3D numerical models to explore the effects of far-field stress orientations on shear strain and dilation localization in the region. Our aim is to understand relationship between farfield stress orientations and fault reactivation and its control on mineralization. The structure of the numerical model represents a simplified version of the Laverton architecture constructed by Geo science Australia. The model contains the Celia fault, Childe Harold fault. Wallaby fault and Sunrise shear zone. The model is subject to a range of deformation orientations and conditions. NW-SE to NNW-SSE shortening leads to sinistral shearing in the Laverton fault system. These shortening directions are favourable for structural reactivation (shear and dilation) at the Wallaby deposit site. The Sunrise site also shows some shear localization and dilation under such conditions but to a lesser degree. ENE-WSW shortening leads to dextral shearing in the fault system. This produced enhanced shear and dilation on the Sunrise fault at the Sunrise deposit, while the Wallaby system showed decreased dilation under this stress regime. Several other far-field stress orientations are unfavourable for fault reactivation in the Laverton region. These results support the hypothesis that the Wallaby fault system was more favourably oriented for mineralisation under sinistral shearing, whereas the Sunrise fault system was more favourably oriented for mineralisation during dextral shearing.
THE lEOLOGICAL SOBETY OF AUSTRALIA INBORPORATED
MEMBERSHIP APPLICATION MEMBER BENEFITS • Subscription to the Australian Journal of Earth Sciences • Four issues of The Australian Geologist per year • Affiliation witli your State or Territory division • Reduced registration rates to the leading biennial national geoscience conference, the Australian Geological Convention • Bivisional meetings and field trips held regularly across Australia • Specialist Groups offering events and information focussing on your discipline • Opportunities to connect and engage with Earth Science professionals around Australia
Send applications to the Sydney Business office: Geological Society of Australia Suite 706, 301 George Street Sydney N S W 2000 Tel: (02) 9290 2194
TO PROMOTE, ADVANCE A N D SUPPORT THE EARTH SCIENCES W I T H I N THE SCIENTIFIC A N B WIDER COMMUNITIES
International Tel:
+ 61 2 9290 2194 Fax: (02) 9290 2198
International Fax:
+ 61 2 9290 2198 Email: info@gsa.org.au
W e b : www.gsa.org.au
Geological Society of Australia Incorporated Objectives
A u s t r a l i a n Geological C o n v e n t i o n
Joint M e m b e r
The Society's objectives are to promote,
The 19th convention is held in conjunction
Joint Members are recognised partners of
as the Australian Earth Sciences Convention
category requirements. Joint Members have
2008 in Perth (AESC).
Member privileges excluding the journal.
Publications
Retired Member
advance and support the Earth Sciences
within the scientific and wider comnnunities. Benefits The Geological Society of Australia gives members an outstanding opportunity to
keep in touch with scientific developments,
present the results of their work, and contribute to discussions on vocational and scientific
topics. As the premier Australian geoscience society, membership provides an essential
network of contacts as well as publications, meetings, events, field trips, symposia and benefits including:
• Subscription to an internationally recognised and peer-reviewed scientific journal. The Australian Journal of Earth Sciences or an alternative membership journal choice of Alcheringa, the publication of the Association of Australasian Palaeontologists. • Subscription to the GSA's magazine The Australian Geologist and to geoz, the GSA's international electronic bulletin. • Divisional meetings held regularly
an existing Member and fulfil the Member
with the Australian Institute of Geoscientists
Australian Journal
of Earth
A Member of the Society of at least ten years
Sciences
standing who has retired from professional
(Scientific journal, 8 issues p.a.), Alcheringa (Palaeontology journal, 4 issues p.a.). The
practice is eligible to apply for Retired Mem-
Abstracts of Conventions, Divisional and
and have the option of membership with or
Australian
bership. Retired Members retain all privileges
Geologist (TAG, 4 issues p.a.);
Specialist Group books and field guides. AJES
without the journal.
on-line only. All Members receive TAG.
Student Member
is available as either hard copy & on-line, or
Student members are enrolled full/part-time
Member
studying Earth Sciences at a tertiary institu-
tion or a secondary school, and must provide
Members are usually graduates of a university or other tertiary institution with a major in Earth Sciences, or graduates actively engaged in work relating to Earth Sciences. In special circumstances the Executive Committee may approve for Membership:
certification from their Head of Department on this application form. Includes students
at undergraduate and postgraduate level. Stu-
dent members receive the Australian Journal of Earth Sciences and the GSA online newsletter and a hard copy of The Australian
(a) people who have been employed in some technical aspect of Earth Sciences for a period of at least five years or
higher fee, rather than the Australian
with a Specialist Group for additional charges
published the results of research
or receive a hard copy of the Australian
in the Earth Sciences.
on current topics.
various Specialist Groups.
Graduate Member
There shall be no specific qualifications
• Reduced registration rates for the biennial Australian Geological Convention.
• Member prices for the GSA's Special
required of Associate Members, but every
Graduate Members are recently qualified
old, and should produce evidence of a genuine
for two years, normally immediately after
other non-commercial group may become an
AJES via internet only.
Earth Scientists. This category is only available
candidate for election must be at least 18 years
applicants complete studies and includes
interest in the Earth Sciences. A school or
Publication series. • Member Advantage - The GSA membership benefits package.
Associate Member. People who are eligible for Membership cannot be Associate Members,
unless normally a resident outside Australia.
Annual Membership Fees: All fees quoted are in Australian dollars Membership is f r o m January t o D e c e m b e r ; members joining after July have the option to pay 50% of the fees and receive publications from
July to December only (this option excludes 'Student Membership with journal online only and without journal', and Specialist Group subscription fees). Overseas m e m b e r s please add additional postage of AU$25 for the journal and AU$ 15 for The Australian
Journal hard copy + on-line
Journal on-line only
Geologist
OVERSEAS - GST EXEMPT
AUSTRALIA - GST INCLUSIVE Membership rates and category
Without journal
Membership rates and category
Journal hard copy + on-line
Journal on-line only
Without journal
MEMBERSHIP
$165.00
$150.00
N/A
MEMBERSHIP
$165.00
$150.00
N/A
ASSOCIATE
$165.00
$150.00
$90.00
ASSOCIATE
$165.00
$150.00
$90.00
RETIRED
$85.00
$75.00
$45.00
RETIRED
$85.00
$75.00
$45.00
STUDENT (AJES)
$85.00
$10.00
$10.00
STUDENT
$85.00
$75.00
$45.00
STUDENT (ALCHERINGA)
$20.00
N/A
N/A
GRADUATE
N/A
$88 00
N/A
GRADUATE
N/A
$88.00
N/A
JOINT WITHOUT JOURNAL
N/A
N/A
$90.00
JOINT WITHOUT JOURNAL
N/A
N/A
$90.00
S P E C I A L I S T G R O U P S U B S C R I P T I O N F E E S ((CATERING FOR SPECIAL INTERESTS). AUSTRALIAN COSTS INCLUDE GST Aust.
Aust.
O/seas
O/seas $5.50
APPLIED GEOCHEMISTRY
$5.50
$5.50
GEOCHEMISTRY, MINERALOGY & PETROLOGY
$5.50
COAL GEOLOGY
$16.50
$16.50
PALAEONTOLOGY (ALCHERINGA)
$38.50
38.50
EARTH SCIENCE HISTORY
$8.80
$8.80
PLANETARY GEOSCIENCE
$5.50
$5.50
ECONOMIC GEOLOGY
$3.30
$3.30
SEDIMENTOLOGY
$5.50
$5.50
EDUCATION
$5.50
$5.50
SOLID EARTH GEOPHYSICS
$13.20
$13.20
TECTONICS & STRUCTURAL GEOLOGY
$1 1.00
$1 1.00
VOLCANOLOGY
$1 1.00
$1 1.00
ENV., ENG. & HYDROGEOLOGY
Journal
of Earth Sciences for an additional fee.
Associate M e m b e r
• Optional membership to
Journal
of Earth Sciences. Students may be associated
(b) people who have undertaken and
across Australia featuring speakers
Geologist.
Students may choose Alcheringa for a slightly
$5.50
$5.50
Application for membership
Suite 706, 301 George Street Sydney N S W 2000 Tel: (02) 9290 2194 Fax: (02) 9290 2198
of the Geological Society of Australia Incorporated
Email: info@gsa.org.au W e b : www.gsa.org.au
PERSONAL DETAILS
DIVISIONAL AFFILIATION I W I S H T O BE AFFILIATED TO THE F O L L O W I N G DIVISION:
SURNAME: (Prof. / Ass. Prof. / Dr / Mr / Mrs / Ms / Miss) O T H E R NAME(S):..
..DATE O F BIRTH:.
PHONE: (Business hours)
PHONE: (After hours)
FAX: (Business hours)
FAX: (After hours)
•
!\CT
•
vJSW
•
•
>A
•
^LD
•
nC
•
/VA
•
>JT
•
"AS
IH
•
JOURNAL
IV
1 HAVE PREVIOUSLY BEEN A MEMBER OF THE SOCIETY
BUSINESS NAME:
•
DNLINEONLY
•
DNLINE A N D H A R D C O P Y
BUSINESS ADDRESS:
OR . STATE:.
•
. P/CODE:..
HARDCOPY :MAIL ,FOR ACT NSW, SA, QLD, VIC, TAS)
MEMBERSHIP HISTORY
AUSTRALIAN J O U R N A L OF E A R T H S C I E N C E S (AJES)
SUBURB:
• •
A S PART O F M E M B E R S H I P I W I S H T O RECEIVE:
EMAIL: .
DIVISIONAL NEWSLETTER
•
<ES if yes resignation date:
•
MO
\ L C H E R I N G A (Palaeontology)
OR H O M E ADDRESS:
•
....
SUBURB:. PREFERRED A D D R E S S FOR: (TICK A BOX)
SWE:
P/CODE:
CORRESPONDENCE (Including publications)
•
BUSINESS
•
/VITHOUT J O U R N A L
MEMBERSHIP CATEGORY HOME
i, T H E U N D E R S I G N E D , APPLY FOR:
MEMBERSHIP REGISTER • BUSINESS • HOME The nnembership register includes contact details for nnembers of the society and is produced every two years and is only available to members.
SPECIALIST GROUP AFFILIATION
I.
•
\DMISSION TO THE CATEGORY INDICATED B E L O W
•
FRANSFERFROM
2.
•
MEMBER
•
\SSOCIATE MEMBER
I W I S H T O BE AFFILIATED W I T H T H E F O L L O W I N G SPECIALIST G R O U P S : (OPTIONAL - FOR ADDITIONAL FEE REFER TO PREVIOUS PAGE)
• APPLIED GEOCHEMISTRY • COAL GEOLOGY • EARTH SCIENCE HISTORY • ECONOMIC GEOLOGY • EDUCATION • ENVIRONMENTAL, ENGINEERING & HYDROGEOLOGY
• GEOCHEMISTRY, MINERALOGY
SPONSORS' CERTIFICATION FOR ADMISSION OF APPLICANT TO SOCIETY W E , BEING MEMBERS OF THE G E O L O G I C A L SOCIETY OF
•
O I N T MEMBER W I T H (NAME)
•
RETIRED M E M B E R
•
& PETROLOGY
• PALAEONTOLOGY • PLANETARY GEOSCIENCE • SEDIMENTOLOGY • SOLID-EARTH GEOPHYSICS • TECTONICS & STRUCTURAL GEOLOGY • VOLCANOLOGY
>TUDENT M E M B E R .COMPLETE CERTIFICATE ON FOLLOWING PAGE)
•
J F E MEMBER
•
GRADUATE MEMBER
PAYMENT Fees are for a calendar year or 50% for half year (see previous page for details) O P T I O N A L C O M M E N C E M E N T DATES: •
^ULLYEAR Jtarts 1st January
•
MEMBERSHIP FEE:
$
C O N S I D E R H E R / H I M T O BE E L I G I B L E T O J O I N T H E S O C I E T Y .
SPECIALIST G R O U P S : (Optional)
$
SIGNATURE:.
OVERSEAS POSTAGE: $ (If applicable)
AUSTRALIA CERTIFY THAT W E K N O W THE A P P L I C A N T A N D
NAME:
SIGNATURE:.. NAME:
TO:
TOTAL:
HALF Y E A R itarts I St July
(not available for $10 Students or Specialist Groups subscription fees)
$
BY C H E Q U E : A T T A C H E D IS A C H E Q U E FOR
AUS $
OR
BY CREDIT CARD:
APPLICATION DECLARATION
DEBIT MY:
•
/ISA
•
'lASTERCARD
I C O N F I R M T H A T T H E I N F O R M A T I O N P R O V I D E D IN T H I S A P P L I C A T I O N IS T R U E A N D C O M P L E T E A N D , IF E L E C T E D , I A G R E E T O A B I D E BY T H E R U L E S OF THE SOCIETY A N D THE SOCIETY'S C O D E OF ETHICS FOR GEOLOGISTS. DATE: SIGNATURE:.
EXPIRY DATE: SIGNATURE:
T U R N OVER FOR STATEMENT OF QUALIFICATIONS
Statement of qualifications Please complete the relevant section OR attach current curriculum vitae
..OTHER NAME(S):.
SURNAME: ....
APPLICANTS FOR MEMBER, JOINT, ASSOCIATE, STUDENT AND GRADUATE MEMBERSHIP . YEAR: .
FIRST DEGREE OR DIPLOMA HELD: UNIVERSITY OR INSTITUTE:.
. YEAR:
SECOND DEGREE OR DIPLOMA HELD: UNIVERSITY OR INSTITUTE: MAJOR SUBJECTS STUDIED IN UNDERGRADUATE COURSE (E.G. GEOLOGY MATHS): IF GEOLOGY/GEOPHYSICS WERE NOT MAJOR SUBJECTS TO WHAT LEVEL WERE THEY STUDIED:... EMPLOYMENT HISTORY: LIST IN CHRONOLOGICAL ORDER STARTING WITH MOST RECENT EMPLOYMENT EMPLOYER(S)
FROM
TO
POSITION HELD
EMPLOYMENT CATEGORY:
(TICK ONE BOX ONLY)
•
MINERALS INDUSTRY
•
PETROLEUM INDUSTRY
•
SURVEYS, CSIRO, G O V DEPTS
•
ENGINEERING
•
SELF-EMPLOYED. CONSULTANT
•
TERTIARY INSTITUTE
•
ENVIRONMENTAL
•
OTHER
APPLICANTS FOR ASSOCIATE MEMBERSHIP SPECIAL INTERESTS:.,
APPLICANTS FOR STUDENT MEMBERSHIP UNIVERSITY OR INSTITUTE: UNDERGRADUATE / HONOURS / POST GRADUATE
COURSE BEING STUDIED: STUDENT CERTIFICATE:
I CERTIFY THAT (NAME): IS A STUDENT AT (INSTITUTE): NAME (HEAD OF SCHOOL/DEPT):.. DATE: .
SIGNATURE:
OFFICE USE ONLY DIVISION
DATE
DATE
RECEIVED
LISTED
APPROVED
ADMITTED
FEDERAL
DATE
MEMBER #
Supporting
Geoscientists
AUSTRALIAN INSTITUTE OF GEOSCIENTISTS Supporting Geoscientists
Application for Membership
The Australian Institute of Geoscientists (AIG) is a non-profit professional association which represents geoscientists in fields ranging from regional geology, geophysics and geochemistry, information geoscience, metalHferous, coal and petroleum exploration, development and production, industrial minerals, environmental geoscience, hydrogeology, geotechnical engineering/geology and other speciahst geoscience areas. Members are employed in all sectors of industry, research, education and government throughout Australia and overseas. The AIG aims to advance the skills, status and public perception of geoscientists and geoscience in the community. The broad base of the AIG encourages transfer of technical expertise and awareness of both professional development and employment opportunities both within and outside traditional, resource-based geoscientific activities.
Australian Institute of Geoscientists P.O. Box 8463 PERTH BUSINESS CENTRE WA 6849 e-mail aig@aig.Qrg.au web site v^ww.aig.org.au
Australian Institute of Geoscientists
GENERAL INFORMATION
The objectives for which the AIG is established are to:
Promote interaction between geoscientists Promote community respect for geoscience and geoscientists Promote professional development of geoscientists Represent geoscientists
BENEFITS OF AIG MEMBERSHIP
Benefits of AIG Membership include:
Membership of a dynamic Institute focussed exclusively on the professional interests of members. Eligibility to sign mineral resource statements and reports issued for public information under the JORC Code (with appropriate relevant experience required of the Competent Person). Optional registration as a Registered Professional Geoscientist (RPGeo), provides a verifiable, personal commitment to ongoing professional development. Discounted registration fees for AIG seminars and conferences. Exclusive access to professional mentoring services. AIG News, distributed to all members four times a year. Full access to AIG's on-line information services, providing up to date news and information of interest to professional geoscientists across Austraha (visit AIG's web site at www.aig.Qrg.au) AIG Journal - AIG's technical journal, published on-line and providing members with a forum for the rapid publication of papers and short technical notes dealing with any aspect of applied geoscientific practice and research in a peer reviewed publication
AIG Members contribute to:
• Representation of geoscientists at a national and state level in professional matters within industry, the broader scientific community and government. • Monitor, maintain and strive to continuously improve the professional standards and ethics of geoscientists. • Support for geoscience education. • Promotion of the role and standing of geoscientists within the community.
Membership
INFORMATION FOR APPLICANTS
Members of the Institute may be (a) Fellows, (b) Members, (c) Graduates, (d) Associates, (e) Students or (f) Retired Members, being persons who have been transferred or elected to these respective grades. An additional voluntary grade of Registered Professional Geoscientist is available. To be eligible for election as, or transfer to a Fellow (FAIG), an applicant must be a geoscientist with not less than fifteen years experience in their Field(s) of Practice who has in the opinion of the Council, achieved prominence in such field. A supporting statement must accompany this form and applicants are advised to refer to guidelines, which can be found at www.aig.org,aji in preparing this statement. To be eligible for election as a Member (MAIG), an applicant shall be a geoscientist having not less than five years experience in their Field(s) of Practice, such experience having been of a responsible nature and involving the exercise of independent judgment during at PO Box 8463 Perth Business Centre WA 6849
e-mail aig@aig.org.au
web site www.aig.org.au
Australian Institute of Geoscientists
least three of those years. An applicant having worked towards completion of a post graduate qualification recognised by the Council may count up to two years of post-graduate training towards the requirement of five years of experience necessary to be eligible for membership as a Member. A Member shall also possess a degree, diploma, certificate of qualification or some other qualification recognised by the Council demonstrating competence in their Field(s) of Practice. Members and Fellows (with the appropriate relevant experience required of the "Competent Person") are entitled to sign resource statements and reports issued for public information under the JORC Code. To be eligible for election as a Graduate, an applicant must possess a degree, diploma, certificate of qualification or some other qualification recognised by the Council demonstrating competence in their Field(s) of Practice. To be eligible for election as an Associate, an applicant should be a person or organisation (e.g. a non commercial organisation such as a school) who does not hold formal qualifications in geoscience but displays appropriate interest in the objectives of the Institute. A statement supporting the applicant's interest should accompany this application. To be eligible for election as a Student, an applicant will not as yet have achieved the educational qualifications to apply for membership as a Graduate and will be enrolled in undergraduate or honours degree studies majoring in a geoscience field at a recognised Tertiary Institution. A member of staff of the Tertiary Institute must verify this in Section 6 of this form. To be eligible for transfer to Retired, an applicant will have been a Member or Fellow continuously for at least ten years and have retired from active employment.
Documentation required to accompany this application Academic Qualifications Copies of degree(s) certificate(s) or certified statements from institutions of academic qualifications MUST accompany this form. Qualifications must be in a geoscience related field except in the case of Associates. Where geology or geoscience is not specified in the award, an academic transcript detailing subjects studied should also be provided. Proposers and Seconders This application MUST be endorsed by proposers and seconders who are AIG members. If you do not know any AIG members to act as proposers, persons of equivalent standing in your industry sector may be considered. Please contact the Membership Committee or your State Branch for assistance. Relevant Employment and Experience Applicants for admission as a Fellow, Member, Graduate or Associate, or for transfer of membership from Graduate to Member or Member to Fellow MUST submit a Curriculum Vitae documenting their employment history, publications and education details. Each entry in Section 4 of this form must be verified by your proposer and seconder. Payment Payment MUST accompany this application. Registration Existing Members and Fellows may apply for election as a Registered Professional Geoscientist (RPGeo). A registration kit will be sent to applicants upon request. Applications for RPGeo will be processed by the Registration Board of the AIG. A once only application fee of $90 ($99 incl GST) and annual membership fees of $100 ($110 incl GST) apply for RPGeo Members. To receive an RPGeo application kit, please tick the box (Application Checklist) on page 6.
PO Box 8463 Perth Business Centre WA 6849
e-mail aig@aig.org.au
web site www.aig.org.au
Australian Institute of Geoscientists
APPLICATION FOR MEMBERSHIP OF THE AUSTRALIAN INSTITUTE OF GEOSCIENTISTS Section 1. Personal Details
P L E A S E P R I N T U S I N G B L O C K CAPITALS Date of Birth:
Surname: Given Name(s):
Title:
Preferred Name: Residential Address:
Address for Correspondence:
Home
Business Telephone: Facsimile: Mobile Phone: E-mail Address:
YES / YES /
Do you wish to be notified of AIG meetings, seminars and ottier events by e-mail? Do you wish to receive AIG newsletters by e-mail
Please tick the appropriate item
Section 2. Application Details New Applicants
NO NO
(Note: fees to accompany application)
Tick
GST*
Total
$50.00
$5.00
$55.00
Subscription
I wish to apply for membership as a Student
FREE
I wish to apply for admission as a Graduate
FREE
I wish to apply for admission as an Associate
$70.00
$7.00
$77.00
I wish to apply for admission as a Member
$90.00
$9.00
$99.00
I wish to apply for membership as a Fellow
$90.00
$9.00
$99.00
Subscription
GST*
Total
Transfers
(Note: fees to be paid on invoice)
I wish to apply for transfer of membership from Graduate to Member
$90.00
$9.00
$99.00
I wish to apply for transfer of membership from Member to Fellow
$90.00
$9.00
$99.00
I wish to apply for transfer of membership to Retired
$35.00
$3.50
$38.50
* Note GST not applicable to overseas applicants. Membership concessions (such as for citizens/residents of developing countries) can be considered on a case-by-case basis at the discretion of the Council. Please contact the Membership Committee for more information.
PO Box 8463 Perth Business Centre WA 6849
e-mail aig@aig.or.g.au
web site www.aig.org.au
Australian Institute of Geoscientists
Section 3. Academic Qualifications To be completed by applicants for/transfer to Graduate, Member or Fellow.
Qualification Awarded
^ e.g.
Tertiary Institution
Year Conferred
Major Geoscience Subjects*
geochemistry, hard-rock geology, mining geology, coal geology, sedimentology, petroleum, geophysics, hydrogeology, environmental geoscience
Section 4. Summary of Relevant Employment and Experience To be completed by applicants for/transfer to Graduate, Associate, Member or Fellow and MUST be verified by Proposer.
From
To
mm/yyyy
mm/yyyy
Employer
Position Held
Proposer's Initials
Section 5. Proposer's Declaration To be completed by proposers and seconders on behalf of applicants for/transfer to Graduate, Associate, Member or Fellow. INFORMATION FOR PROPOSERS 1.
Proposers should initial each entry in Section 4 above (Proposer's Initials) of which they have personal knowledge.
2.
If a proposer cannot vouch for part of the experience in Section 4, then the applicant must nominate a responsible person who can provide verification.
3.
The maintenance of AIG standards depends to a great extent on the degree of responsibility exercised by proposers. They must not rely on hearsay; when initialling an item in Section 4, they must know this information to be true.
W e the undersigned A I G m e m b e r s certify that w e have personal k n o w l e d g e of the applicant and their professional career and consider the applicant fulfils the conditions f o r a d m i s s i o n as a G r a d u a t e / Associate / M e m b e r / Fellow, or transfer of m e m b e r s h i p f r o m G r a d u a t e to M e m b e r / M e m b e r to Fellow (cross out where not applicable). Name (Block Letters)
Signature
Date
M'Ship Number (office use)
Proposer: Seconder:
PO Box 8463 Perth Business Centre WA 6849
e-mail aig@aig.org.au
web site www.aig.org.au
Australian Institute of Geoscientists
Section 6. Confirmation of Student Status To be completed by a Staff member of Geoscience Department (University of enrolment) on behalf of applicants for Student Membership.
I certify that the applicant is currently undertaking part time or full time undergraduate/honours studies majoring in a geoscience field at the following tertiary institution. Signature:
Position: Institution
Date:
Institution:
Expected Date of Completion
Ordinary
Honours
Section 7. Applicant's Declaration To be completed by all applicants
I certify that the information provided is true and complete and agree to be bound by the Australian Institute of Geoscientists Code of Ethics (copy attached). Date:
Signature:
Section 8. Membership subscription Please find enclosed my CHEQUE for $
payable to Australian Institute of Geoscientists, or
Please Charge $
Bankcard
to my CREDIT CARD
Card No:
Expiry Date!
Mastercard 1
Visa
(mm/yy) Signature:
Name on Card:
SUBMISSION OF APPLICATION Completed forms should be forwarded to AIG's business office - PO Box 8463 Perth WA 6849. Receipt of apphcations for membership will be confirmed by mail or e-mail. Successful applicants will be notified of acceptance of their application in writing. If you have any queries about how to fill in this form, please telephone 08 9427 0820, or email aig@aig.org,au Further information regarding AIG may be obtained from the Institute's office at the address above, or from the Institute's web site at w ^ m M & M Z m
Application Checklist Please complete the checkhst to confirm your application is complete. ALL information MUST be supplied with application unless where greyed out except in the case of transfers where subscriptions will be invoiced in July. Student
Graduate
Associate
Member
Fellow
Retired
Personal details complete Application Details confirmed Summary of academic qualifications provided Certified copy of qualifications attached (if not previously supplied) Summary of employment history provided Continued over page ... PO Box 8463 Perth Business Centre WA 6849
e-mail aig(j
web site www.aig.org.au
Australian Institute of Geoscientists
Student
Graduate
Associate
Member
Fellow
Retired
CV / supporting statement attached Employment summary items confirmed by proposers Statement of professional achievement/prominence attached Confirmation of Student Status complete Proposer's declaration complete Application signed Membership Subscription included
I am interested in becoming an RP Geo. Please send me an RP Geo Application Kit
THE AIG AND YOUR PRIVACY The AIG recognises the importance of your privacy and understands your concerns about the security of your personal information. We care committed to protecting any personal information about you that we hold. From December 2001, the AIG is bound by the National Privacy Principals as set out in the Commonwealth Privacy Act 1988. The AIG will only collect that personal information which is necessary to fulfil its functions and activities. Personal information will not be passed on to third parties for commercial purposes under any circumstances. The following is information the Privacy Act requires us to communicate to all members and non-members of the AIG. It is recommended that you keep this information for future reference. All AIG office bearers, secretariat, staff, contractors and appointed volunteers must adhere to the provisions of the AIG privacy policy. Your Personal Information Personal information held by the AIG may include: Name Address Telephone Numbers Email Addresses Facsimile Numbers Qualifications Other information, such as employment history, comments by peers, etc as at the time of membership or RPGeo application. How the AIG collects Personal Information The AIG may collect personal information direcdy from individuals at time of application for membership or RPGeo or in regular requests for updated information. The AIG may also collect information when you use our website (www.aig.org.au). The only personal information the AIG collects when you use our website is what you tell us about yourself; for example when registering for a conference we may record your contact details and email address or when you register on the Directory of Austrahan Geoscientists or the AIG Geoscience Professional Guide we may record contact details and information about your qualifications and experience. How the AIG uses your Personal Information Your personal information may be used in order to: • Provide the professional and membership services you require; • Inform you of ways the services to you could be improved; • Research and develop our services. When we disclose your Personal Information • The AIG may disclose personal information to statutory and regulatory authorities (such as the Australian Stock Exchange (ASX) upon request. • The AIG may confirm an individual's membership when membership of the AIG is claimed. • The AIG may confirm qualifications held by a member, when that member publicly claims such qualifications. Access, Accuracy and Secure Storage Individuals may request and be provided with access to their personal information. Requests for access should be made in writing and will, wherever possible be granted as soon as possible. The individual making the request must be able to confirm their identity prior to disclosure of any personal information. The AIG undertakes to treat personal information in a confidential and secure manner to maintain this information's accuracy and completeness. The AIG recommends that you promptly advise of any changes in your personal information such as your name, contact details and qualifications. Should your require any further information concerning privacy please contact the AIG at aig@aig.org.au or phone 08 9427 0820 fax 08 9427 0821.
PO Box 8463 Perth Business Centre WA 6849
e-mail aig@aig.org.au
web site www.aig.org.au
Australian Institute of Geoscientists
AUSTRALIAN INSTITUTE OF GEOSCIENTISTS CODE OF ETHICS 1. Definitions For the purposes of this Code, unless the context otherwise requires, member shall mean any person admitted to any grade of membership of the Institute; Institute shall mean the Australian Institute of geoscientists; Council shall mean the board of directors and governing council of the Institute; Ethics and Standards Committee shall mean the Ethics and Standards Committee duly constituted and regulated by the Council under Article 55 of the Institute's Articles of Association; the male gender shall include the female gender and the singular shall include the plural, and vice versa. 2. Principle Members shall discharge their duties with fidelity to the public, their employers and clients, and at all times in their professional or employed capacities carry out their work with competence, integrity and professional responsibility. 3. Application This Code shall apply to all members including Graduates, Members, Fellows and Registered Professional Geoscientists of the Institute. 4. Duties In all working decisions and recommendations, a member shall have due regard for the welfare and safety of the community which may be affected by the work for which he is responsible or which may result from his recommendations. All members are required to conform to this Code so as to uphold the dignity of their profession and to maintain the highest possible level of conduct in all professional matters. 5. Matters of Fact A member shall avoid and discourage exaggerated and unwarranted statements. If called upon to give evidence or otherwise to speak on a matter of fact a member shall state what he believes to be the truth with scrupulous impartiality. 6. Matters of Opinion Provided that the matter is clearly expressed as an opinion, a member may, where require, give a considered professional opinion based on facts, experience, interpretation, extrapolation or a combination of these. 7. Public Comment In any public written or verbal comment, a member shall be careful to state whether the statements or assertions made therein represent facts, an interpretation of facts, an opinion, or a behef. In all such circumstances, a member shall act only with propriety in criticising the ability, opinion or integrity of another member, person or organisation. 8. Intra-Professional Conduct A member shall neither intentionally nor negligently do anything to injure, direcdy or indirecdy, the reputation, prospects or business of another member. However, if he considers a member to be guilty of unethical, illegal or unfair practice, it is his duty to present his views and the relevant information to the Council. 9. Unfair Advantage A member shall not use the advantages of former or present status or position to compete unfairly with members in private practice, nor use unfairly the advantages of private practice to the detriment of salaried members. 10. Limitation A member shall engage or advise his employer or client to engage, and cooperate with, other experts and specialists whenever the employer's or client's interests would be best served by such service. He shall not accept a concealed fee for referring a client or employer to a specialist or for recommending services other than his own. 11. Training of Subordinates When in a position of authority over other members of the profession, a member shall take care to see that those under his direction are afforded every reasonable opportunity to advance their knowledge and experience. 12. Credit to Others A member shall ensure that proper credit is given to any associate, subordinate or otherwise, who has contributed to work for which he is responsible or whose work is being reviewed. 13. Acceptance of Favours A member shall avoid placing himself under any obligation to any person or organisation who might deal with his employer or client. He shall not accept any substantial favours from such person or organisation. 14. Patents or Information A member shall not receive, either directiy or indirectiy, any royalty, gratuity or commission in respect of any patented or protected article or information or process used in any work with which he may be connected unless he shall have fully disclosed the fact, in writing, to his employer, client or fellow professionals and associates in this matter. 15. Confidential Information A member shall not use for any personal gain or advantage, nor shall he disclose, confidential information which he may acquire as a result of special opportunities arising out of work done for his client or employer, without the consent in writing of his client or employer or until it is clear that there can no longer be a conflict of interest with the original client or employer. 16. Contract Preparation and Supervision In the planning of work, preparation of plans, reports, specifications and contract documents and in the supervision of work, a member shall have due regard for and protect the interests of his client or employer, who he shall represent with the utmost good faith. However, in the interpretation of all contract documents, he shall maintain an attitude of scrupulous impartiality as between his client and employer on the one hand and the contractor on the other and shall, as far as he can, ensure that each party to the contract shall discharge his respective duties and enjoy his respective rights as set down in the contract or agreement.
PO Box 8463 Perth Business Centre WA 6849
e-mail aig@aig.org.aii
web site www.aig.org.au
Australian Institute of Geoscientists
17. Consulting Practice
A member shall not describe himself, nor permit himself to be described as a consultant in his particular branch or branches of the profession unless he occupies a position of professional independence and is able to act as an unbiased and independent adviser. When acting as a consultant he shall conform in all respects with the Code of Ethics of this Institute. He shall not knowingly accept professional work in connection with which another member has been appointed to act, except in collaboration with such other member, unless he be formally notified by the Client that he is required to act, and that the other member has been appropriately notified. He shall not tender nor knowingly compete with any other member for employment on the basis of professional charges. He shall not conduct himself in a manner or act in any capacity nor hold any appointment which, in the opinion of the Council, prejudices his status as a Consultant or the interests of the Institute. Members who are directors or responsible officers of companies carrying on a practice as Consultants should endeavour to ensure at all times that the professional practice of the company conforms to the spirit of the Institute's Code of Ethics.
18. Governmental and Organisational Requirements
A member shall have knowledge of and strictly comply with all laws and regulations relating to his professional activities and shall comply with the rules of any related professional organisation to which he belongs.
19. Financial Market Regulatory Authority
A member shall comply strictly with the Code for the Technical Assessment and Valuation of Mineral and Petroleum Assets and Securities for Independent Expert Reports ("VALMIN Code") and the rules, regulations and practices as established and promulgated by the Australian Stock Exchange with respect to the Australian Stock Exchange Listing Rules for mining and other companies
20. Responsibility
The administration of this Code and matters related to it shall, subject to Article 55 of the Institute's Articles of Association, be vested in the Ethics and Standards Committee. Any matter of misconduct or negligence related to this Code shall be referred by the Council to the Ethics and Standards Committee for recommendation on appropriate action to be taken.
21. Non-Compliance with the Code
Where the Ethics and Standards Committee is of the opinion that a member has breached any provision of the Articles or this Code, the member shall be: disciplined including being suspended from membership under the provisions of Article 15 and AIG's Complaints Management System as amended from time to time, or expelled by the Council from membership of the Institute, subject to Article 15 of the Institute's Articles of Association.
ARTICLES OF ASSOCIATION REFERRED TO IN THE CODE OF ETHICS
Article 14. A member may at any time by giving notice in writing to the Secretary resign his membership of the Institute but shall continue to be liable for any annual subscription and all arrears due and unpaid at the date of his resignation and for all other moneys due by him to the Institute and in addition for any sum not exceeding $50.00 for which he is liable as a member of the Institute under Clause 5 of the Memorandum of Association of the Institute. Article 15. If any member shall wilfully refuse or neglect to comply with the provisions of the Memorandum or Articles of Association of the Institute or the Code of Ethics or shall be guilty of any conduct other than that specified in Regulation 14 hereof which in the opinion of the Council is unbecoming of a member or prejudicial to the interest of the Institute, the Council shall have the power to discipline or suspend the membership of a member under the provisions of the Code of Ethics by imposing one or more penalties as it thinks fit or expel the member from the Institute and erase his name from the Register of Members provided that at least fourteen days before the meeting of the Council at which a resolution for his expulsion is passed the member shall have had notice of such meeting and of what is alleged against him and of the intended resolution for his expulsion and that he shall at such meeting and before the passing of such resolution by at least two thirds of members of Council ehgible to vote have had an opportunity of giving orally or in writing any explanation or defence he may think fit. The Code of Ethics may be amended from time to time by the Council. Article 55. The Council may delegate any of its other powers (not being duties imposed on the Council as directors of the Institute by the Act or general law) to sub-committees consisting of such member or members of the Council or Institute as it thinks fit; any sub-committee so formed (herein called a Permanent Committee) shall in the exercise of the powers so delegated conform to any regulations that may be imposed on it by the Council and subject thereto shall have power to co-opt any member or members of the Institute. All members of such Permanent Committee shall have one vote. All decisions of Permanent Committees shall be subject to ratification by Council. There shall initially be a: (i) Quahfications Committee; (ii) Ethics and Standards Committee; (iii) Legal Committee; and (iv) Registration Board. [Note there is now a Complaints Committee in addition to those above]
EXTRACT FROM MEMORANDUM OF ASSOCIATION REFERRED TO IN THE CODE OF ETHICS
Clause 5. Every member of the Institute undertakes to contribute to the assets of the Institute, in the event of the same being wound up while he is a member, or within one year after he ceases to be a member, for payment of the debts and liabilities of the Institute contracted before he ceases to be a member, and of the costs, charges, and expenses of winding-up and for the adjustment of the rights of the contributories among themselves, such amount as may be required, not exceeding $50.00.
Supporting
PO Box 8463 Perth Business Centre WA 6849
G®osci
e-mail aig:@aig.org.au
web site www.aig.org.au
274 EXHIBITOR DETAILS Anglo American Exploration (Australia) Pty Ltd Kristen Mann, Executive Assistant Suite 1,16 Brodie-Hall Drive Bentley, WA 6102, Australia T: +61 8 6250 8100 / F: +61 8 6250 8199 E: kristenmann@angloamerican.com.au www.angloamerican.co.uk Stand No: 46
Consolidated Minerals Tim Craske, Chief Geologist 28 Ventnor Avenue West Perth WA 6005, Australia T: +61 8 9321 3633 / F: +61 8 9321 7533 E: tcraske@consminerals.com.au www.consminerals.com.au Stand No: 10
Department of Industry and Resources WA Geological Survey of Western Australia Dr Tim Griffin, Executive Director 100 Plain Street East Perth, WA 6004, Australia T: +61 8 9222 3168/F:+61 8 9222 3633 E: geological.survey@doir.wa.gov.au www.doir.wa.gov.au/gswa Stand No: 47-48
AuScope Ltd Ms Tracy Paroz, Business Manager Sir James Foots Building (47A) University of Queensland St Lucia, QLD 4072, Australia T: +61 7 3346 4133 / F: +61 7 3346 4134 E: tracy@auscope.org www.auscope.org Stand No: 75
CRC Leme Steve Rogers, Chief Executive Officer 26 Dick Perry Avenue Kensington, WA 6151, Australia T: +61 8 6436 8695 / F: +61 8 6436 8555 www.crcleme.org.au Stand No: 77
Department of Mines and Energy Queensland John Tuttle, Geoscience Manager Block A, 80 Meiers Road Indooroopilly, QLD 4068, Australia T: +61 7 3362 9360 www.dme.qld.gov.au Stand No: 16
Australian Institute of Geoscientists Ron Adams, Secretariat 36 Brisbane Street East Perth WA 6004, Australia T: +61 8 9427 0820 / F: +61 8 9427 0821 E: aig@aig.asn.au www.aig.asn.au Stand No: 44
CSA Global Patrick Maher, Senior Geologist Level 1, 47 Burswood Road Burswood, WA 6100, Australia T: +61 8 9355 1677 / F: +61 8 9355 1977 E: patrick.maher@csaglobal.com www.csaglobal.com Stand No: 81
Digirock Pty Ltd Peta Libby, Director 7 Beverley Terrace South Guildford, WA 6055, Australia T: +61 8 9477 3747 / F: +61 8 9477 4388 E: peta@digirock.com.au www.digirock.com.au Stand No: 85
Australian Mineral Fields Marcus Willson, President & CEO Suite 18, 44 Parliament Place West Perth, WA 6005, Australia T: +61 8 9215 4222 / F: +61 8 9226 1799 www.australianmf.com Stand No: 91
CSIRO Exploration i&Mining Dr David Gray, Acting Theme Leader, Discovering Australia's Mineral Deposits PO Box 1130, Bentley, WA 6151, Australia Ph: +61 8 6436 8678 / Fax: +61 8 6436 8555 E-mail: david.gray@csiro.au www.csiro.au Stand No.: 69
Downing Teal Pty Ltd Russell Boylan, Team Leader - Mining Level 1, 76 Kings Park Road West Perth, WA 6005, Australia T: +61 8 9481 2424 / F: +61 8 9481 0159 E: rboylan@downteal.com www. do wningteal. com Stand No: 6
Boart Longyear Sean Fitzgerald, Sonic Drilling Operations Manager 21 Carolyn Way Forrestfield, WA 6058, Australia T: +61 8 6216 8500 / F: +61 8 9454 5487 E: sjfitzgerald@boartlongyear.com www.boartlongyear.com Stand No: 15
EGRU at James Cook University Curtin University of Technology Economic Geology Research Unit WA School of Mines WASM Administration, WA School of Mines James Cook University Acting EGRU Manager Locked Bag 22 Townsville, QLD 4811, Australia Kalgoorlie, WA 6433, Australia Ph: +61 8 9088 6179 / Fax: +618 9088 6179 T: +61 7 4781 4726 / F: +61 7 4781 4020 E: egm@jcu.edu.au E-mail: WASMadmin@curtin.edu.au www.es.jcu.edu.au/research/egm www. wasm. curtin .edu.au Stand: 82 Stand No.: 14
Centre for Exploration Targeting, University of Western Australia Prof T. Campbell McCraig, Director 35 Stirling Highway Crawley, WA 6009, Australia T: +61 8 6488 2 6 6 7 / F : + 6 1 6488 1178 E: norae.fisher@uwa.edu.au www.cet.uwa.edu.au Stand No: 4
Datamine Australia Steven Hodgson, Technical Services Manager 23 Belgravia Street Belmont, WA 6104, Australia T: +61 8 9479 1771 / F:+61 8 9479 1115 E: steve@datamine.com.au www. datamine .co.uk Stand: 73
Fugro Airborne Surveys & Ground Geophysics Pty Ltd Tim Taylor, Business Development Manager Locked Bag 6 Wembley, WA 6014, Australia T: +61 8 9273 6400 / F: +61 8 9273 6466 E: ttaylor@fugroairbome.com.au www. fugroairbome .com Stand No: 18
CODES University of Tasmania Prof Ross Large, Director Private Bag 126 Hobart, TAS 7000, Australia T: +61 3 6226 2472 / F: +61 3 6226 7662 E: ross.large@utas.edu.au www. codes, utas. edu. au Stand No: 92
Datgel Phil Wade, Managing Director 8, 89-97 Jones Street Ultimo, NSW 2007, Australia T: +61 2 9281 6118 / F:+61 2 9281 6137 E: phil@datgel.com.au www. datgel. com. au Stand No: 72
Genalysis Laboratory Services Pty Ltd Gary Wheeler, Business Development Manager 15 Davison Street Maddington, WA 6109, AustraUa T: +61 8 9251 8100/F:+61 8 9751 8110 E: genalysis@genalysis.com.au www.genalysis.com.au Stand No: 93
Australian Earth Sciences Convention 2008
EXHIBITOR DETAILS 275 Geoforce Pty Ltd Reece Foster, Geophyicist 1,288 Victoria Road Malaga WA 6090, Australia T: +61 8 9209 3070 / F: +61 8 9209 3071 E: reece@geoforce.com.au www. geoforce. com. au Stand No: 12
Gold Fields Sharon Andrews, Mineral Resource Administrator PO Box 359 Kambalda WA 6442, Australia T: +61 8 9088 1168/F:+61 8 9088 1112 E: sharon.andrews@goldfields.com.au www.goldfields.co.za Stand: 17
Mineral Resources Tasmania Geoff Green, Managing Geologist PO Box 56 RosnyPark Tas 7018, Australia T: +61 3 6233 8335 / F: +61 3 6233 8338 E: ggreen@mrt.tas.gov.au www. mrt. tas. go V. au Stand No: 71
Geological Society of America Gary Lewis, Director of Education & Outreach 3300 Penrose Place Boulder CO 80301, USA T: +303 357 1043 / F: +303 357 1000 E: glewis@geosociety.org www.geosociety.org Stand No: 8
GPX Airborne Greg Reudavey, Chairman 11 Willcock Street Ardoss WA 6153, Australia T: +61 8 9316 8111 / F : + 6 1 8 9316 8033 E: greg.reudavey@gpxair.com.au www.gpxairbome.com.au Stand: 9
Mira Geoscience Asia Pacific Pty Ltd Tim Chalke, Senior Geoscientist Level 1, 1 Swann Road Taringa QLD 4068, Australia T: +61 7 3377 6789 / F: +61 7 3377 6701 E: timc@mirageoscience.com www.mirageoscience.com Stand No: 95
Geological Society of Australia Inc Sue Fletcher, Executive Director / Anna Roulette Hobley, Membership & Publications Co-ordinator Suite 706, 301 George Street Sydney, NSW 2000, Australia T: +61 2 9290 2194 / F: +61 2 9290 2198 E: info@gsa.org.au www.gsa.org.au Stand No: 97-98
Innov-X Systems Australia Pty Ltd Andrew Somers, General Manager Suite 27, 45 Ventnor Ave West Perth WA 6872, Australia T: +61 8 9389 4496 / F: +61 8 9389 4400 M:+61 448 810 111 E: ASomers@innovxsys.com Stand No: 78
Norilsk Nickel Australia Kate Luke, Team Assistant - Geology Level 3, 88 Collins Street West Perth WA 6005, Australia T: +61 8 9426 0102 / F: +61 8 9481 4077 E: kate.luke@nomik.com.au www.nomik.ru/en/our_products/ norilsknickelaustralia/ Stand: 96
Geological Survey of NSW NSW Department of Primary Industries Simone Meakin, Senior Geologist - Publications 57 High Street, Maitland, NSW 2320, Australia T: +61 2 4931 6666 / F:+61 2 4931 6700 E: simone.meakin@dpi.nsw.gov.au www. dpi. ns w. gov. au/minerals Stand: 45
Jabiru Metals Ltd Gary Comb, Managing Director PO Box 1114 West Perth WA 6872, Australia T: +61 8 9426 8300 / F: +61 8 9426 8399 E: info@jabimmetals.com.au www.jabimmetals.com.au Stand No: 94
Portman Limited Catarina Forzatti HR& Payroll Advisor Level 11,1 William Street "The Quadrant" Perth WA 6000, Australia T: +61 8 9426 3361 / F: +61 8 9426 3350 E: cforzatti@portman.com.au www.portman.com.au Stand: 43
Geoscience Australia Peter Southgate GPO Box 378 Canberra ACT 2601, Australia T: +61 2 6249 9206 E: peter.southgate@ga.gov.au www.ga.gov.au Stand No: 2-3
J Mills Distribution Panasonic Toughbook Mark Stevens, Sales Manager 8 Cressall Road Balcatta WA 6021, Australia T: 0401 045 106 / Fax: +61 8 9345 1308 E: marks@mills.com.au www.jmills.com.au Stand: 70
Predictive Mineral Discovery ^Cooperative Research Centre Dr Bob Haydon, Chief Executive Officer School of Earth Sciences, The University of Melboume, Melboume, VIC 3010, Australia T: +61 3 8344 6514 / F:+61 3 8344 8359 E: rhaydon@unimelb.edu.au www.pmdcrc. com. au Stand No: 80
GeoScience Victoria Department of Primary Industries Damia Ettakadoumi, Project Liaison GPO Box 4440 Melboume Vic 3001, Australia T +61 3 9658 4532 / F: +61 3 9658 4555 E: damia.ettaadoumi@dpi.vic.gov.au www.dpi.vic.gov.au/minpet Stand No: 5
Krucible Metals Limited Marcus Harris, Chairman PO Box 499 Townsville Qld 4812, Australia T: +61 7 4772 5880 / M: 0417 965618 F:+61 7 4772 4999 E: marchus.harris@kmciblemetals.com.au www.kmciblemetals.com.au Stand: 83
Resource Information Unit (RIU) Rob Tyson / Nina Dimitrova General Manager / Marketing Manager 79 Hay Street Subiaco WA 6008, Australia T: +61 8 9382 3955 / F: +61 8 9388 1025 E: rtyson@riu.com.au; adimitrova@riu.com.au www.riu.com.au Stand: 76
Geosoft Australia Pty Ltd Tanya Brown, Marketing & Business Assistant Unit 14, 400 Railway Road Subiaco WA 6008, Australia T: +61 8 9382 1900/F:+61 8 9382 1911 E: tanya.brown@geosoft.com www.geosoft.com Stand No: 99
Maxwell GeoServices Viv Preston, Director Level 1, 25 Cantonment Street Fremantle WA 6160, Australia T: +61 8 9432 1777 / F: +61 8 9432 1778 E: vpreston@maxwellgeoservices.com www.maxwellgeoservices.com Stand No: 74
Rio Tinto Shannon Garcia, Communications and Extemal Relations 152-158 St Georges Tee, Perth, WA 6000, Australia T: +61 8 9327 2000 E: extemalrelationswa@riotinto.com www.riotinto.com Stands: 88/89/90 Australian Earth Sciences Convention 2008
276 EXHIBITOR DETAILS & FLOOR PLAN Taylor & Francis Customer Service Co-ordinator Level 2,11 Queens Road Melbourne Vic 3004, Australia T: +61 3 9866 2811 / F: +61 3 9866 8822 E: enquiries@tandfcom.au www. informaworld. com Stand No: 87 Terra Search Pty Ltd David Jenkins, Director Level 12, 120 Briggs Street Welshpool, WA 6106, Australia T: +61 8 9472 8546 / F: +61 8 9472 8548 E: sarah.ts@iinet.net.au www.terrasearch.com Stand No: 86
Sietronics Pty Ltd Fred Hoetmer, WA Sales Manager 19/24 Baile Road Canning Vale WA 6155, Australia T: +61 8 9455 5781 /F:+61 8 9455 5651 E: spl@sietronics.com.au www.sietronics.com.au Stand No: 13 Society of Economic Geologists Brian G Hoal, Executive Director 7811 Shaffer Parkway Littleton, Colorado 80127-3732, USA T: +1 720 981 7882 / F: +1 720 981 7874 E: seg@segweb.org www.segweb.org Stand No : 79
UTS Geophysics David Abbott, General Manager Fauntleroy Avenue Perth Airport WA 6105, Austraha T: +61 8 9479 4232 / F: +61 8 9479 7361 E: info@uts.com.au www.uts.com.au Stand No: I Wiley" Blackwell Suneel Jethani, Senior Marketing Manager Frontier Koishikaw^a Bldg Level 2, 155 Cremome Street Richmond, VIC 3121, Australia T: +61 3 9274 3171 / F: +61 3 9274 3342 E: suneel.jethani@asia.blackwellpublishing.com www.wiley.com/wiley-blackwell Stand No: 84
178 771 [ 179 761 180
1
1
1
L.^
Buffet
L
13 6 1 14 5 1 15 4 1 J
116 3 |17 2 | 1 8 1?
j
94 93 92 91 95 90 96 89 97 88 98 87 99 iTi—II
Australian Earth Sciences Convention 2008
181 741] 182 731 183 7 2 !
1
184 711 185 701 186—J 691 1
j
1
— f l s
a
VENUE FLOOR PLAN PC EC - Level 1
PAVILION 2
! PAVILION 3
c I
EXHIBITION PAVILION 4
EXHI ITION PAVILI H
CONVENTION CFNTRE & BACK Of HOOSt
:mci ' »UFT j
(
!
I
ACCESS FROy A MOUNTS BAY ROAD I
CITY i
MEDINA GRAND HOTEL
PCEC ~ Level 2 SWAN RIVER
STAIRS & E S C A L A T O R S TO L E V E L 1
VIEWS DISABLED L I F T F A C I L I T I E S
S U M M E R GARDEN
I