Issuu

Geological Society of Australia

ABSTRACTS Number

21®^ Victorian Universities Earth and Environmental Sciences Conference

September 2007 La Trobe University

Victorian Universities Earthi and Environmental Sciences Conference

VUE LA

T RO B E

7 September 2007

La Trobe University

Geological Society of Australia Abstract Volume Number 88

Victorian Universities Earth and Environmental Sciences Conference Geological Society of Australia Abstracts Number 86

Editors:

Sarah Hagerty Dale McKenzie Yohannes Yihdego

ISSN: 0729 011X © Geological Society of Australia Incorporated, 2007

Preferred citation for this volume: Hagerty, S.H., McKenzie, D.S. and Yihdego, Y. (editors). 21®^ Victorian Universities Earth and Environmental Sciences Conference, September 2007, Geological Society of Australia Abstracts No 86.

Example citation for papers in this volume Hart, C.V., 2007 Surface and groundwater interactions of the Gleneig River, western Victoria, Australia. In: Hagerty, S.H., McKenzie, D.S. and Yihdego, Y. (editors). Victorian Universities Earth and Environmental Sciences Conference, September 2007, Geological Society of Australia Abstracts No 86.

Copies of this publication may be obtained from: The Business Manager Geological Society of Australia Incorporated Suite 706 Thakral House, 301 George Street Sydney NSW 2000 Australia

Victorian Universities Earth & Environmental Sciences Conference Geological Society of Australia Abstracts Number 88 Editors: Sarah Hegarty Dale McKenzie Yohannes Yihdego

ISSN: 0729 011X © Geolgical Society of Australia Incorporated, 2007

Preferred citation for this volume: Hagerty, S.H., McKenzie, D.S. and Yihdego, Y. (editors). Victorian Universities Earth & Environmental Sciences Conference, September 2007, Geological Society of Australia Abstracts No 88. Example citiation for papers in this volume Hart, C.V., 2007 Surface and groundwater interactions of the Gleneig River, western Victoria, Australia. In: Hagerty, S.H., McKenzie, D.S. and Yihdego, Y. (editors). 21^Wictorian Universities Earth & Environmental Sciences Conference, September 2007, Geological Society of Australia Abstracts No 88.

Copies of this publication may be obtained from: Publications Co-ordinator Geological Society of Australia Incorporated Suite 706, 301 George Street Sydney NSW 2000 Australia

21st Victorian Universities Earth & Environmental Sciences Conference

VUEESC t A T ROBE

TECHNICAL PROGRAM 8:00 am

Registration Opens

9:00 am

Opening and welcome by Prof. David Finlay (Dean, Faculty of Science, Technology & Engineering)

Yohannes Yfhdego

Martin Fusseil

Hydrogeological constraints on the hydrology of Lake Burrumbeet, southwestern Victoria

Surface and groundwater interaction In the Murrumbldgee Valley, New South Wales

10:00 am

Morning Tea

10:30 am

Session 2: Climatology 11:00

10:45

10:30

9:45

9:30

9:15

Catherine Hart

Salinity and surface and groundwater interactions of the Gleneig River, western Victoria

11:15

Linden Asiicroft

Belinda Meneghini

Catherine Ganter

Audrey Hasson

Polar outbreaks in southern Australia: synoptic and planetary links

Understanding the behaviour of the northern and southern modes in the past decade

A new climatology of the characteristics of atmospheric 'blocking' using modern reanalysis data sets

Assessing the impact of climate change on fire weather

11:30

12:00

11:45

Sara Jakaica

Jay Stafford

Kim Ely

Tectonic controls on largescale landscape processes In Australia

Pattern and timing of geological fault structures formed in extensional tectonic environments

Asian Origin for the Alleu Complex, East Timor

12:15 am

Lunch

(Poster Session 1:00 - 1:30 pm)

2:00 Katherine Coady

1:45 Matthias Raiber

1:30 Matt Ryan Using water and salt balance modelling to

Spatial variability of

Interpretation of salinity

quantify the effect of b(ue-gum planta-

groundwater recharge in the

processes on groundwater

tions on water resources in the Eastern

regional-scale basalt aquifer in

in the Bet Bet catchment,

Dundas Tableland, western Victoria

western Victoria

central Victoria

2:15 Rachel Brick

2:30 Louise Edwards

2:45 Christian Seiier

High-pressure rocks in the Palaeoproterozoic: geodynamic evolution of 2.0 Ga eclogltes in the Usagaran Orogen, Tanzania

Whole Rock Analyses. What are they good for? Melt inclusions and mineral chemistry in the Sulu Ranges, New Britain Arc

Thermal imprint of an incipient passive margin - an example from Baja California (Mexico)

3:00 pm

Afternoon Tea

3:30 pm

Session 6: Meteorology

3:30 Tristan Oakley

3:45 Luke Garde

4:00 Mobashwera Kabir

Terrain induced

The unusual cyclone "Donald": large scale perspectives and comparison with the first South Atlantic hurricane

Understanding the inconsistencies between two different sources of Morton's aaet data for Ranger Uranium Mine site, Northern Territory, Australia

turbulence: case study of Mount Archer, Queensland, Australia

4:15 pm

Session 7: Geodynamics and Economic Geology 4:45 Megan Hough

4:15 Robin Armit

4:30 Larriana Morgan

Geodynamic evolution of a

Depositional history of the

The nature of gold

Proterozoic crustal-scale shear

Corunna Conglomerate and its

minera I isation in the Woods

zone: constraints from deformation,

stratlgraphic relationship to the

Point - Walhalla Goldfields/

metamorphism and geochemistry

Gawier Range Volcanics

eastern Victoria

5:00 pm

Buffet Dinner and Drinks

5:30 pm

Award Presentation and Closing Remarks

SPONSORS The Organising Committee for the 21®^ Victorian Universities Earth & Environmental Sciences Conference would like to thank the following sponsors for their generous support:

ExxonMobil

E^i^onMobil

http://www.exxonmobil.com.au

Department of Primary Stat«Covemment ^

Department of

Primary Industries

Industries http://www.dpi.vic.gov.au

Faculty of Science, Technology and

LA TROBE

• • u n T V E R S IT Y

Engineering, La Trobe University http://www.latrobe.edu.au/ scitecheng

Geological Society of Australia, Victoria Division http://www.vic.gsa.org.au

VICTORIA DIVISION

International Association of Hydrogeologists, Victoria Branch http://www.iah.org.au

Geological Society of Australia http://www.gsa.org.au

Predictive Mineral Discovery Cooperative Research Centre http://www.pmdcrc.com.au

pmd CRC School of Earth Sciences, University of Melbourne http://www.earthsci.unimelb.edu.

THE UNIVERSITY OF

MELBOURNE

PostGraduate Niche www.pgn.com.au

PostGraduate Niche

Environmental Jobs Network http://www.envjronmentaljobs.

environmental

jobs network

com.au

CONTENTS Groundwater/Surface Water Interactions SURFACE AND GROUNDWATER INTERACTIONS OF THE GLENELG RIVER, WESTERN VICTORIA, AUSTRALIA C. V. Hart and J. A. Webb

HYDROGEOLOGICAL CONSTRAINTS ON THE HYDROLOGY OF LAKE BURRUMBEET, SOUTHWESTERN VICTORIA Y. Yihdego and J. A. Webb

SURFACE AND GROUNDWATER INTERACTION IN THE MURRUMBIDGEE VALLEY, NEW SOUTH WALES M. Fussell

Climatology POLAR OUTBREAKS IN SOUTHERN AUSTRALIA: SYNOPTIC MECHANISMS AND PLANETARY LINKS L. Ashcroft

UNDERSTANDING THE BEHAVIOUR OF THE NORTHERN AND SOUTHERN ANNULAR MODES IN THE PAST DECADE B. Meneghini and I. Simmonds

A NEW CLIMATOLOGY OF THE CHARACTERISTICS OF ATMOSPHERIC 'BLOCKING' USING MODERN REANALYSIS DATA SETS C. J. Ganter and I. Simmonds

ASSESSING THE IMPACT OF CLIMATE CHANGE ON FIRE WEATHER A. Hasson, K. Walsh, B. Timbal and G. Mills

Tectonics TECTONIC CONTROLS ON LARGE-SCALE LANDSCAPE PROCESSES IN AUSTRALIA S. Jakica and M. Sandiford

PATTERN AND TIMING OF GEOLOGICAL FAULT STRUCTURES FORMED IN EXTENSIONAL TECTONIC ENVIRONMENTS J. L. P. Stafford

ASIAN ORIGIN FOR THE AILEU COMPLEX, EAST TIMOR K. S. Ely and M. Sandiford

Hydrogeological Processes USING WATER AND SALT BALANCE MODELLING TO QUANTIFY THE EFFECT OF BLUE-GUM PLANTATIONS ON WATER RESOURCES IN THE EASTERN DUNDAS TABLELAND, WESTERN VICTORIA M. Ryan

SPATIAL VARIABILITY OF GROUNDWATER RECHARGE IN A REGIONALSCALE BASALT AQUIFER IN WESTERN VICTORIA M. Raiberand J. A. Webb

INTERPRETATION OF SALINITY PROCESSES ON GROUNDWATER IN THE BET BET CATCHMENT, CENTRAL VICTORIA K. CoadyandJ.A. Webb

Geochemistry and Crustal Processes HIGH-PRESSURE ROCKS IN THE PALAEOPROTEROZOIC: GEODYNAMIC EVOLUTION OF 2.0 GA ECLOGITES IN THE USAGARAN OROGEN, TANZANIA R. A. Brick and A. S. Collins

WRA (WHOLE-ROCK ANALYSES)! WHAT ARE THEY GOOD FOR? MELT INCLUSIONS AND MINERAL CHEMISTRY IN THE SULU RANGES, NEW BRITAIN ARC L. Edwards, L. Danyushevsky, J. Hergt and J. Woodhead

THERMAL IMPRINT OF AN INCIPIENT PASSIVE MARGIN - AN EXAMPLE FROM BAJA CALIFORNIA (MEXICO) C. Seller, A. J. W. Gleadow, B. P. Kohn, J. M. Fletcher and R. Mendoza-Borunda

Meteorology TERRAIN INDUCED TURBULENCE: CASE STUDY OF MOUNT ARCHER, QUEENSLAND, AUSTRALIA T.W.N. Oakley

THE UNUSUAL CYCLONE "DONALD": LARGE SCALE PERSPECTIVES AND COMPARISON WITH THE FIRST SOUTH ATLANTIC HURRICANE L. A. Garde, A. B. Pezza and J. A. T. Bye

UNDERSTANDING THE INCONSISTENCIES BETWEEN TWO DIFFERENT SOURCES OF MORTON'S AAET DATA FOR RANGER URANIUM MINE SITE, NORTHERN TERRITORY, AUSTRALIA M. Kabir, G. M. Mudd and A. R. Ladson

Geodynamics and Economic Geology GEODYNAMIC EVOLUTION OF A PROTEROZOIC CRUSTAL SCALE SHEAR ZONE: CONSTRAINTS FROM DEFORMATION, METAMORPHISM AND GEOCHEMISTRY R. J. Armit, P. G. Betts and B. F. Schaefer

DEPOSITIONAL HISTORY OF THE CORUNNA CONGLOMERATE AND ITS STRATIGRAPHIC RELATIONSHIP TO THE GAWLER RANGE VOLCANICS, GAWLER CRATON, SOUTH AUSTRALIA L. M. Morgan, P. G. Betts and B. F. Schaefer

THE NATURE OF GOLD MINERALISATION IN THE WOODS POINT WALHALLA GOLDFIELDS, EASTERN VICTORIA M. Hough, F. P. Bierlein, L. Ailleres, S. Hutchin and A. Seymon

Posters HYDROGEOLOGY & SALINITY PROCESSES IN THE MOUNT MERCER ILLABAROOK AREA G. D. Mockunas

A PLIOCENE SEA SURFACE TEMPERATURE RECONSTRUCTION FOR SOUTHEASTERN AUSTRALIA USING THE MODERN ANALOGUE TECHNIQUE C. L. Li, S. J. Gallagher and J. Bye

SOLUBLE AND MINERALIZABLE CARBON FROM ORGANIC AMENDMENTS INFLUENCE AGGREGATION IN HIGH CLAY, SODIC SOIL G. J. Clark, C. Tang and P. W. G. Sale

STRONTIUM ISOTOPES AND RADIOCARBON DATING HELP TO DETERMINE GROUNDWATER FLOWPATHS IN THE UPPER LODDON CATCHMENT, CENTRAL VICTORIA S. K. Hagerty, J. A. Webb and G. E. Jacobsen

THE EFFECT OF NITROGEN FORM, DCD AND EDDS ON ZINC PHYTOEXTRACTION BY THLASPI CAERULESCENS, LUPINUS ALBUS AND L PILOSUS A. C. Monsant, C. Tang and A. J. M Baker

LAKE WATER-MASS BALANCE MODELLING AS A PREDICTIVE TOOL FOR WATER QUALITY MANAGEMENT M. Raiber and J. A. Webb

PHOSPHORUS STRATIFICATION UNDER DIFFERENT TILLAGE SYSTEMS IN THREE CONTRASTING VICTORIAN SOILS D. T. Vu, C. Tang and R. Armstrong

EIGHT YEARS OF DISTICHLIS SPICATA GROWTH IMPROVES SOIL PROPERTIES IN A SALINE DISCHARGE ZONE M. Sargeant, C. Tang and P. Sale

SALT PRIMING IMPROVES THE ESTABLISHMENT OF DISTICHLIS SPICATA IN SALINE CONDITIONS M. Sargeant, P. Sale and C. Tang

ORGANISING COMMITTEE Sarah Hagerty

Katherine Coady

Conference Convenor

Catering Coordinator

Website and Communication Abstract Editor

Matthias Raiber Facilities Coordinator

Catherine Hart Program Coordinator

Yohannes Yihdego Abstract Editor

Matthew Ryan Sponsorship and

Dale McKenzie

Marketing Coordinator

Abstract Editor

Session 1 Groundwater/Surface Water Interactions

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

SURFACE AND GROUNDWATER INTERACTIONS OF THE GLENELG RIVER, WESTERN VICTORIA, AUSTRALIA C. V. Hart^ a n d J. A . W e b b ^ ^Department of Environmental Science, La Trobe University, Bundoora, Victoria, Australia The surface and ground water of the Gleneig River in western Victoria are used extensively for agricultural and domestic/urban supplies, but are under threat due to the rise in salinity levels of the Gleneig River even though environnnental flows are diverted into the river from Rockland Reservoir to maintain the water quality. A preliminary study identified a major input of saline groundwater using chemical and isotopic analysis. A more detailed study covering a greater area was required to assess the impact of the groundwater input from the Dundas Tablelands to the south and to model the effect on water quality of various environmental flows and change in climate. The salinity levels in the Dundas Tablelands regional groundwater flow system fluctuates, however generally increases from east to west (1500-7000mg/L). Salt is exported through runoff Key words: salinity, stable isotopes, hydrogeology Email: cathart6@hotmail.com

from surface and baseflow into streams. Local systems, highly dependent on rainfall and local landscape, are of higher salinity with EC values from 1000-18000MS/cm, also increasing from east to west, significantly contributing to salinisation through stream discharge. The salinity of the Gleneig River is highly variable laterally and seasonally. A peak in salinity is present downstream of Rocklands Reservoir, (5000-13150|jS/cm). This decreases downstream due to dilution by surface water, but there are sharp fluctuations further downstream due to further groundwater input, particularly form the saline lake systems found within the Douglas Depression. Ongoing analysis of major ions and stable isotope analysis of O^® and H^ will be used to supply further evidence of surface and ground water interactions.

Session 1 Groundwater/Surface Water Interactions

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

HYDROGEOLOGICAL CONSTRAINTS ON THE HYDROLOGY OF LAKE BURRUMBEET, SOUTHWESTERN VICTORIA Y. Yihdego^ and J. A. Webb^ ^Departnnent of Environmental Science, La Trobe University, Bundoora, Victoria, Australia

using borehole data, show that the deep lead drained towards the north, in the opposite direction to the present drainage. The influences of rainfall, evaporation, runoff and groundwater input and output have been modelled to construct a water budget for Lake Burrumbeet. The results indicate there is significant groundwater outflow from the lake, in contrast to other lakes in western Victoria which have been modelled. Determination of the geological cause of the ground water leakage is difficult due to the complexity of the hydrogeological system, but the lake may be leaking into the deep lead system through the volcano. To verify this groundwater flow path, the use of geochemical constraints, including isotopic data, will be necessary, to complete the development of 3D conceptual hydrogeological model, including boundary conditions.

Lake Burrumbeet in southwestern Victoria is underlain by Newer Volcanics basalt lavas, which overlie deep lead sediments deposited in a buried palaeovalley incised into Palaeozoic basement. The voluminous basalts completely filled the deep lead valleys, closing down their well established drainage system and changing the location of the drainage divide. Using digital elevation models, drill logs and airborne geophysics maps geological cross sections have been constructed for the Lake Burrumbeet aquifer system to improve our understanding of the complex hydrodynamics of the system. Hydrographs from nested bores show that the deep lead and basalt are not acting as a single aquifer, but the confining layer between them (the weathered surface of the deep lead system) is breached by the intrusive neck located beneath a volcano at the margin of Lake Burrumbeet. The basement paleo-topography and deep lead sediment thickness, constructed

Key words: conceptual model, pre-basaltic surface, water budget, deep lead system, hydrogeology Email: vvihdegowoldevQhanne@students.latrobe.edu.au

Session 1 Groundwater/Surface Water Interactions

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

SURFACE AND GROUNDWATER INTERACTION IN THE MURRUMBIDGEE VALLEY, NEW SOUTH WALES M. F u s s e i r ^Department of Environmental Management and Ecology, La Trobe University, Albury-Wodonga, Australia

Since the nnid 1990's and increasingly throughout the recent drought, there has been an increase in the reliance upon groundwater in the Murrumbidgee valley for both civil and agricultural uses. The Department of Natural Resources in New South Wales has an interest in quantifying the impact of groundwater extraction on the Murrumbidgee River, including within region of the valley between Wagga Wagga and Narrandera where groundwater extraction is prevalent. The aim of the work detailed here is to determine the amount of recharge to the groundwater the groundwater system in this area from different sources. Two aquifers are recognised, the lower one consisting of unconsolidated quartz sand of late Tertiary age. This aquifer generally has better quality and higher yield volumes and is relied upon more heavily as a source of water. The upper aquifer is unconfined and contains various

levels of water bearing sand or which the degree of connection between the river and the upper aquifer also needs to be determined. Previously, the lower aquifer has been considered largely confined, but there may be a variable degree of connection between the two aquifers throughout the valley. Evidence from hydrographs indicates that the river in the study area is a losing stream and that there is some connection between the river and the aquifers, as changes in river level appear to produce a response in both aquifers. Longer term decreases in the storage levels of the lower aquifer indicate that full recharge is not occurring. Initial chemical data indicate that the connection between the two aquifers is spatially variable and recharge from the upper to the lower aquifer may be due as much to precipitation and flow through as the river.

Key words: Murrumbidgee, groundwater-surface water interaction, recharge Email: M.Fussell@latrobe.edu.au

Session 2 Climatology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

POLAR OUTBREAKS IN SOUTHERN AUSTRALIA: SYNOPTIC MECHANISMS AND PLANETARY LINKS L. Ashcroft^ ^School of Earth Sciences, University of Melbourne, Parkville, Victoria, Australia Polar outbreaks are an important feature of southern Australian weather. Although they may only occur infrequently, these incursions of air from higher latitudes can have a significant impact on the agricultural industry. Much environmental and economical damage has occurred in the past due to frosts and other phenomena associated with a polar outbreak. These unseasonably cold changes can also impact greatly on day to day living. The synoptic situations associated with extremely cold days in Melbourne and Perth from 1958-2001 are examined, and the temporal and spatial tracks of both cyclones and anticyclones plotted using the University of Melbourne cyclonic tracking scheme. A cyclone/anticyclone

dipole is apparent as the dominant pattern leading to polar outbreaks, although other patterns are present. These tracks are analysed seasonally in conjunction with upper level variables. These analyses allow for the exploration of a link between polar outbreaks on the east and west coast of Australia, as well as a potential connection between Australian outbreaks and those in South America. A possible correlation between outbreak frequency and ENSO is explored, as well as the impact of the SAM on outbreak dates and intensity. Seasonal trends are also analysed, to determine if a climate change signature is evident in the presence of polar outbreaks over southern Australia.

Key words: polar outbreak, synoptic patterns, planetary patterns Email: lindenashcroft@gmail.com

Session 2 Climatology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

UNDERSTANDING THE BEHAVIOUR OF THE NORTHERN AND SOUTHERN ANNULAR MODES IN THE PAST DECADE B. Meneghini^ and I. Simmonds^ ^School of Earth Sciences, University of Melbourne, Parkvilie, Victoria, Australia

Atmospheric circulation can exhibit recurring patterns of variability. In the extratropical regions of both hemispheres the dominant patterns are known as the Northern Annular Mode (Northern Hemisphere) and the Southern Annular Mode (Southern Hemisphere). These modes are typically characterised by atmospheric anomalies (difference from the mean) of one sign in the midlatitudes and anomalies of opposite sign in the high-latitudes. It is common to observe such patterns in pressure, wind and temperature for example. Hence, they have become important modes to study from the point of view of their climate impacts. Over the past several decades strong positive trends have dominated in annular mode behaviour (i.e. there has been a tendency towards the positive phase of these modes, or in other words higher pressures over the midlatitudes and lower pressures over the highlatitudes). The positive trends are thought to be the result of greenhouse gas increases and

stratospheric ozone depletion. However, since the early 1990's (Northern Annular Mode), and around the year 2000 (Southern Annular Mode), these modes appear to have experienced a negative trend. This negative trend is unexpected to a large degree because the direction of greenhouse gas and stratospheric ozone changes has remained constant. The aim of this study is to try to explain the cause of the recent negative trend in the Northern and Southern annular modes. One possible explanation could be that greenhouse gas and atmospheric circulation changes have produced large climate trends (e.g. sea-ice and surface temperature), which in turn have began to force the annular modes. This may also be able to account for the negative trend in the Northern Annular Mode commencing before the negative trend in the Southern Annular Mode. Results of our analysis will be presented and discussed.

Key words: Northern Annular Mode, Southern Annular Mode, large-scale circulation, trends, climate change Email: b.meneqhini@pqrad.unimelb.edu.au

Session 2 Climatology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

A NEW CLIMATOLOGY OF THE CHARACTERISTICS OF ATMOSPHERIC ^BLOCKING' USING MODERN REANALYSIS DATA SETS C. J. Ganter^ and I. Simmonds^ ^School of Earth Sciences, University of Melbourne, Parkville, Victoria, Australia responsible for the extensive droughts throughout Eastern Australia in 1982. A modern climatology of blocking in the Southern Hemisphere is formed, and analyzed for climate trends to deduce whether or not global warming has altered the frequency of this phenomenon. We have also examined how well a large-scale global climate model is able to reproduce particular regions of blocking in order to perform sensitivity tests on blocking locations with alterations in sea surface temperature and topography.

Atmospheric blocking is a regular occurrence in the Australian region, and several other areas of the world, and has the potential to greatly affect the surrounding region's seasonal climate. Episodes of prolonged fine weather during summertime over south-eastern Australia can often be attributed to the blocking high pressure system in the adjacent Tasman Sea. These prolonged episodes of fine weather can sometimes contribute to droughts, for example a particularly persistent blocking event that occurred from early June until mid-July in the Tasman Sea was found to be partially

Key words: blocking, climate trends, Australian region Email: c.qanter@uqrad.unimelb.edu.au

Session 2 Climatology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

ASSESSING THE IMPACT OF CLIMATE CHANGE ON FIRE WEATHER A . H a s s o n \ K . W a l s h \ B . T i m b a l ^ a n d G. Mills^ ^School of Earth Sciences, Melbourne University, Melbourne, Victoria, Australia ^ Bureau of Meteorology Research Centre, Melbourne, Victoria, Australia Bushfires of extrenne violence are a nnajor danger to the Australian population since they can claim tens of lives and thousands of houses and animals. To inform the relevant emergency services of the possible hazard for forest fires associated with particular meteorological situations, complex fire indices have been developed based on small scale features such as rainfall, soil moisture, wind speed and direction, and so on. Historic disastrous fire days have also been associated with abnormally deep tropospheric trough systems. These have been analysed using both National Center for Environmental Prediction (NCEP) reanalysis and the European Centre for Medium Range Weather Forecast reanalysis (ERA-40) datasets. These unusual Key words: bushfires, climate change Email: a.hasson@bom.qov.au

synoptic situations are characterised by their intense thermal gradient at the 850 hPa level. The question arises whether the incidence of fire hazard will change in a warmer world. A diagnostic tool based on 850 hPa thermal gradients is applied to 10 IPCC climate models, avoiding the need of the wide range of variables involved in the computation of the complex fire indices. The uncertainty and reliability of the approach are examined for simulations of the twentieth century for each model as well as in the reanalyses. The model results for two contrasting the Special Report on Emissions Scenarios (SRES) scenarios of low and high emissions (A2 and B1) over two twenty-years periods centred on 2050 and 2090 are analysed.

Session 3 Tectonics

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

TECTONIC CONTROLS ON LARGE-SCALE LANDSCAPE PROCESSES IN AUSTRALIA S. Jakica^ and M. Sandiford^ ^School of Earth Sciences, University of Melbourne, Parkville, Victoria, Australia dimensions, is crucial for further understanding of the Cainozoic evolution of Australian landscapes and the active deformation of the continent. Three main study regions have been chosen to demonstrate and better understand the three deformational modes: • The Cainozoic shorelines of the Eucia Basin in southern Australia and their comparison with the shorelines in the offshore region in north and northeast continental margin - for the long wavelength tilting-mode. • The Lake Eyre Region in the central part of South Australia. The stratigraphy, palaeolake strandlines of the Billa Kalina palaeolake, and the undulations in the elevations between the Billa Kalina, Lake Eyre and Torrens basins- for the intermediatewavelength buckling- mode. • The origin of the Darling escarpment. Western Australia, and how does it relates to the rate and deformation to the Australian continent- for the short-wavelength faulting mode. This talk will cover the work performed and results obtained from all three study regions.

Landscape evolution depends on the interactions between crustal defornnation, erosion, and the material properties of the landscape. Intraplate crustal defornnation may be driven from plate boundary forces and/or mantle convection, implying a link between crust and mantle processes and the evolution of Earth's surface. In many settings, the nature of these interactions and the process rates are poorly determined. The Australian plate, one of the world's fastest moving plates, provides an ideal opportunity to study different modes and processes of intraplate deformation and landscape evolution in a variety of structural settings and climates. This research proposes three distinct modes that have been deforming interior of the Australian continent since the onset of the Australian- Antarctic fast spreading (AAD) some 43 Ma. These modes are: 1. A long wavelength continental scale tilting mode, in the order of 10^ km 2. An intermediatewavelength buckling mode, in the order of 10^ km 3. A short wavelength faulting seismogenic mode, in the order of 10^ km. Understanding these modes and their characteristics, such as their spatial and temporal

Key words: dynamic topography, geoid, modes of deformation, Lake Billa Kalina, Lake Eyre, Lake Torrens Email: s.iakica@pqrad.unimelb.edu.au

Session 3 Tectonics

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

PATTERN AND TIMING OF GEOLOGICAL FAULT STRUCTURES FORMED IN EXTENSIONAL TECTONIC ENVIRONMENTS J. L. P. Stafford^ ^School of Geosciences, Monash University, Clayton, Victoria, Australia Two common methods of simulating tensional environments are analogue and numerical models. Numerical models are limited by the computing power available, which restricts the size and detail, which can be modelled. Due to this limitation 2D simulations are common and can be done at high resolutions. While this is a positive step forward in the ultimate understanding of tensional tectonics, direct relationships between 2D models and true life are still relatively difficult to establish. By the use of a numerical modelling code called Underworld, which employs a Langrangian

particle-in-cell finite element scheme, I am examing the patterns and timings of brittle fault structures within the crust in 3 dimensions. Firstly I determine the patterns of fault generation within a 2D model. A third dimension is introduced to these models and the resultant patterns are compared to the 2D simulations. The correlations between the 2D and 3D models are determined. From this it is determined if the 2D models can be of any genuine value for predicting the patterns produced in known geological environments.

Key words: 3D numerical modelling, extension, 2D correlations Email: ilsta3@student.monash.edu.au

Session 3 Tectonics

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

ASIAN ORIGIN FOR THE AILEU COMPLEX, EAST TIMOR K. S. Ely^ a n d M. S a n d i f o r d ^ ^School of Earth Sciences, University of Melbourne, Victoria, Australia becoming the favoured model in more recent times. These alternative sediment sources have very different tectonic implications, particularly concerning the previously suggested link between the deformation of the Aileu Complex and the ongoing collision event. U-Pb dating of detrital zircon using LA-ICPMS demonstrates that sedimentary rocks of the Aileu Complex have a strong affinity with a South East Asian (Sundaland) continental origin. Samples spaced 70 km apart have very similar zircon age spectra, suggesting a single source region for at least this part of the Aileu Complex stratigraphy. Around half of the sample zircons are of Palaeozoic age, with the youngest population indicating a maximum depositional age of around 270 Ma. Proterozoic age modes occur at 9001200 Ma and 1450-2000 Ma. These populations correlate well with the Palaeozoic Malay Peninsula Tin Belt Granites' and underlying Proterozoic basement. It is proposed that the Aileu Complex rifted from Sundaland and moved to near its present day location during the extensive rearrangement of the region that occurred during the Tertiary.

The Neogene collision of the northern nnargin of the Australian continent with the Banda Arc provides an opportunity to investigate the early stages of arc-continental collision processes. East Timor, part of the non-volcanic outer Banda Arc, is a surface expression of this collision; however interpretation of the geology is complicated by the effects of older deformation events. In order to better define pre-collisional deformation events and constrain the tectonic history of East Timor the provenance of the Aileu Complex has been investigated using U-Pb dating of detrital zircon. The Aileu Complex is an intensely deformed and metamorphosed Permian succession extending for 100 km along the north coast of East Timor, representing the collision front. The western part of the Complex comprises subgreenschist grade politic schists with dolerite intrusions. Metamorphic grade increases progressively to the east, reaching upper amphibolite facies in a sequence dominated by mafic gneisses. Both Asian and Australian continental sources have been suggested for the Aileu Complex, with an Australian origin

Key words: U-Pb age, detrital zircon, East Timor, arc-continent collision Email: k.elv@pqrad.unimelb.edu.au

Session 4 Hydrogeologicai Processes

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

USING WATER AND SALT BALANCE MODELLING TO QUANTIFY THE EFFECT OF BLUE-GUM PLANTATIONS ON WATER RESOURCES IN THE EASTERN DUNDAS TABLELAND, WESTERN VICTORIA M. Ryan^ ^Department of Environmental Science, La Trobe University, Bundoora, Victoria, Australia

In recent years the introduction of high-density plantation has occurred at a large scale across the Eastern Dundas Tableland. In some areas, data on sub soil salinity and groundwater levels is available prior to the establishment of the plantations. This has provided a unique opportunity to determine the impact over time of the plantations on recharge and soil, surface and groundwater salinities and resources as the trees reach maturity, and thus a model can be developed to determine possible future effects on water use. A paired catchments study was employed, using a three year-old blue-gum (Eucalyptus globulus) plantation, and a control catchments, used primarily for grazing. The two sites are

adjacent to one and both are small catchments of similar physical and chemical properties, with local groundwater flow systems, and creeks that usually flow throughout the wetter months. Surface- and groundwater samples were taken and analyzed for major ions, to gain further insight into the groundwater-surface water interactions. Stream- and piezometer loggers, together with a small weather station were installed to monitor climatic events and changes to stream-flow and EC, and groundwater levels. The plantation tended to show more extreme seasonal groundwater fluctuations than the control farm, probably due to both preferential recharge (in winter) and groundwater utilization (in summer).

Key words: recharge. Eucalyptus globulus, salinity, plantation Email: ml6rvan@students.latrobe.edu.au

Session 4 Hydrogeological Processes

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

SPATIAL VARIABILITY OF GROUNDWATER RECHARGE IN A REGIONAL-SCALE BASALT AQUIFER IN WESTERN VICTORIA M. Raiber^ and J. A. Webb^ ^Departnnent of Environmental Science, La Trobe University, Bundoora, Victoria, Australia

from the remaining plain are generally old, with the oldest radiocarbon groundwater giving an age of about 22000 yrs BP. These groundwater age and groundwater salinity distribution patterns correlate well with the recharge rates estimated using chloride mass balance. These show that in the vicinity of young eruption points average annual recharge is up to approximately 50 mm/yr (equal to about 7% of the average annual rainfall), whereas the estimated recharge rates in the remaining plain are less than 1 mm/yr (equivalent to less than 0.2% of the annual rainfall). The results of the groundwater and soil analysis indicate that the basalt aquifer is preferentially recharged through the volcanic cones and the youngest basalt phase, where rocky outcrops with highly fractured rock dominate, whereas groundwater recharge through the thick (up to about 10 m), clay-rich soils of the remainder of the basalt plain is very low.

Due to the prolonged drought, the demand for good quality groundwater has increased substantially in recent years in south-western Victoria. A basalt aquifer extends over a large part of this area and contains groundwater of variable composition ranging from fresh water suitable for human consumption to saline brines. In order to manage this precious water resource in a sustainable way, it is important to define the major recharge areas and quantify groundwater recharge across the basalt plains. An array of methods has been applied including remote sensing, reactive and non-reactive natural tracers and unsaturated and saturated zone chloride mass balance. Tritium analyses of fresh shallow groundwaters sampled from the vicinity of eruption points gave modern ages. Radiocarbon analysis of groundwaters from deeper sections within the basalt aquifer in close proximity to the volcanoes also gave comparatively young ^"^C ages, whereas the more saline groundwaters

Key words: basalt aquifer, groundwater salinity, recharge estimation, natural tracers Email: mraiber@students.latrobe.edu.au

Session 4 Hydrogeological Processes

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

INTERPRETATION OF SALINITY PROCESSES ON GROUNDWATER IN THE BET BET CATCHMENT, CENTRAL VICTORIA K. Coady^ and J. A. Webb^ ^Departnnent of Environmental Science, La Trobe University, Bundoora, Victoria, Australia

The upper Bet Bet Catchment, central Victoria, is one of the most saline catchments in Victoria and because of this it has been widely studied. Surface water and groundwater are used heavily for stock and domestic supplies. Dryland salinity is extensive throughout the catchment, saline groundwater contributes high salt loads to the Bet Bet and Loddon River systems. Visible effects can be seen in salt scalds around the central western region and tributaries of the Bet Bet Creek are characterised by severe gully erosion, up to 5 m deep in some areas. To remediate the salinisation of the groundwater and subsequent inflow into the Bet Bet Creek requires a detailed understanding of the hydrology and salt movement through the area. The basement geology of the Bet Bet catchment is Ordovician marine sediment intruded with Devonian granites to the west which have formed the metamorphic ridges of the Ben More and Ben Major ranges, which define the western catchment boundary. There is a

minor basalt outcrop on the eastern boundary from the basalt flows of Mount Mitchell and surrounding volcanic cones. The central valley is blocked at the northern end by the edge of the basalt flow which backed up Bet Bet Creek, filling the valley with Quaternary and Tertiary alluvial sediments. Much of the western slopes are covered by low permeability clay and weathered sandy colluvium, including White Hills Gravel. Recharge occurs primarily along the granite and metamorphic ridges to the west. Groundwater discharge can be seen at the midslope break of slope but primarily discharge occurs in the gullies and streams. Groundwater baseflow into the Bet Bet Creek is between 5000 and 10 000 pS/cm. The general groundwater trend is of moderate salinity on the upper slopes, increasing down slope to extreme salinities in the valley. It is believed that the primary source of saline groundwater is from slow infiltration through heavy clay soils causing concentration of salts in infiltrating rainfall.

Key words: dryland salinity, saline discharge, recharge Email: katherine.coadv@ekit.com

Session 5 Geochemistry and Crystal Processes

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

HIGH-PRESSURE ROCKS IN THE PALAEOPROTEROZOIC: GEODYNAMIC EVOLUTION OF 2.0 GA ECLOGITES IN THE USAGARAN OROGEN, TANZANIA R. A. Brick^ and A. 8. Collins^ ^Continental Evolution Researcii Group, University of Adelaide, 5005, Australia temperature conditions recorded by these eclogites is -18 kbar & -750 °C with amphibolite facies metamorphism recorded throughout the rest of the Usagaran with the exception of the underthrust greenschist facies metasedimentary rocks of the Konse Group. The structural setting of these eclogites is uncertain with suggestion that they formed either during subduction of a stretched or rifted continental margin with subsequent sinistral oblique convergence or that formation was associated with strike-slip tectonics in an island arc regime. A newly completed structural section across the entire Usagaran Orogen is presented here showing structures indicating the presence of at least 2 temporally separate periods of deformation recognised both in field observations and in petrological studies. The timing of these events is investigated using U-Pb zircon geochronology.

High-pressure low-temperature rocks such as eclogites of Palaeoproterozoic age or older are rare in the geological record, a fact which is generally considered to be due to changing geothernnal regimes in the cooling earth. Eclogites 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 Orogen in Tanzania. Eclogite lenses in this location are found amongst felsic gneisses, amphibolites and boudins of ultra basic rocks. The pressureKey words: Tanzania, Palaeoproterozoic, eclogite Email: rachael.a.brick@adelaide.edu.au

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Session 5 Geochemistry and Crustal Processes

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

WRA (WHOLE-ROCK ANALYSES)! WHAT ARE THEY GOOD FOR? MELT INCLUSIONS AND MINERAL CHEMISTRY IN THE SULU RANGES, NEW BRITAIN ARC L. Edwards\ L. Danyushevsky^ J. Hergt^ and J. Woodhead^ ^School of Earth Sciences, University of Melbourne, Victoria, Australia ^CODES, University of Tasnnania, Hobart, Tasmania. Australia

The New Britain arc, lying off the eastern coast of mainland Papua New Guinea, offers a unique insight into the 3D chemical structure of an island arc; in addition to typical arc-front and near reararc ranges (approximately 100km and 200km above the subducting slab, respectively), subaerial volcanism extends to 500km above the subducting slab. Previous studies of quaternary volcanism in the New Britain arc have shown striking chemical trends related to the distance to the Benioff zone; however these data have included only bulk rock analyses of a limited and general sample set taken from across the whole arc. To verify these general across arc trends, detailed study of individual volcanoes in the New Britain arc is required. The Sulu Ranges are a group of arc front composite volcanoes on the central north coast of New Britain. Whole-rock XRF analyses of Sulu lavas give compositions ranging from basalts to

rhyolites, with samples typically containing 3040% phenocrysts supported by a microcrystalline groundmass. Coexisting minerals and olivine-hosted melt inclusions from the most primitive sample from the Sulu Ranges were analysed for major and trace elements. Large variations in olivine, clinopyroxene and plagioclase feldspar compositions and dissolution textures indicate that the majority of crystals were not in equilibrium with a single liquid and are thus xenocrystic. The liquid line of descent (LLD) shown by bulk rock compositions cannot be recreated by simple fractional crystallisation. Estimates of groundmass compositions are used to show whether whole-rock compositions may be used as a proxy for melt compositions, and how melt inclusions are related to macro-scale magmatic reservoirs.

Key words: island arc, melt inclusions, mineral-melt equilibria Email: I.edwards4@pqrad.unimelb.edu.au

Session 5 Geochemistry and Crustal Processes

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

THERMAL IMPRINT OF AN INCIPIENT PASSIVE MARGIN AN EXAMPLE FROM BAJA CALIFORNIA (MEXICO) C. Seiler\ A. J. W. Gleadow\ B. P. Kohn\ J. M. Fletcher^ and R. MendozaBorunda^ ^School of Earth Sciences, University of Melbourne, Victoria, Australia ^Centre de Investigacion Cientifica y de Educacion Superior de Ensenada, Baja California, Mexico

escarpment, with corresponding mean track lengths generally found in the top of an exhumed Partial Annealing Zone (PAZ) of apatite (<7080°C). A sample taken along strike at the base of the escarpment has an AFT age of -BMa and suggests activity on the range-bounding fault in the late Miocene. AFT ages to the east of the escarpment range from 33-42Ma and reflect rotational segmentation of the hanging wall. Activity on the Ballenas transform fault - one of the en echelon transform faults within the gulf axis - is constrained to about 2Ma by partially annealed to reset AFT ages. The thermal signal of the transform fault reflects in the AFT thermo chronometer up to 12km away from the proposed location of the transform fault before ages return to 35-44Ma and mean track lengths to 12-13|Lim, values common to rocks unaffected by the Neogene deformation.

Transfer of the Baja California microplate from the North Annerican to the Pacific plate has been ongoing since the middle Miocene. Early extension occurred within the Gulf Extensional Province (GEP), before localizing into a series of nascent spreading centres and en echelon transform faults in the axis of the Gulf of California. The N striking Sierra La Libertad escarpment is part of the Main Gulf Escarpment, the western margin of the GEP, and exhibits a topographic expression of approximately 800-1000m along its 50km strike length. The steep, eastward concave shape of the escarpment and the westward tilt of volcanic strata in the hanging wall suggest listric fault geometry, probably forming a locally important detachment horizon at depth. Apatite fission track (AFT) ages in a vertical profile decrease from -43Ma near the top of the Sierra La Libertad to -35Ma at the base of the

Key words: Gulf of California, low-temperature thermochronology, fission track. Main Gulf Escarpment, Ballenas transform fault, Bahia de Los Angeles Email: c.seiler@pqrad.unimelb.edu.au

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Session 6 Meteorology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

TERRAIN INDUCED TURBULENCE: CASE STUDY OF MOUNT ARCHER, QUEENSLAND, AUSTRALIA T. W. N. Oakley^ ^School of Earth Sciences, University of Melbourne, Parkville, Victoria, Australia Mount Archer, Queensland, is an isolated mountain with an elevation of 547 m above sea level (ASL). On 20 Decennber 2001, the Australian Transport and Safety Bureau (ATSB) released a report on a fatal helicopter crash that occurred on 29 August 2001. A severe turbulence warning and mountain wave forecast had been issued by the Bureau of Meteorology (BoM). The ATSB report cited severe turbulence as the probable cause of the crash. However, the specific mechanisms that generated the turbulence were not noted. The purpose of this investigation is to simulate the air flow over Mount Archer using the ClarkHall model in two-dimensions. The simulation initially used a smooth bell shaped curve of differing heights and widths to represent Mount Archer. Simulations over complex topography, representative of Mount Archer, were then examined. Analysis of the results indicated the general type of mechanisms that most likely to

have caused the turbulence on the day of the crash. Calculation of the critical wavelength, Richardson number (Ri), Froude number (Fr), dispersion relation and Turbulent Kinetic Energy (TKE) were used to help identify the turbulent regions in the model simulations. The twodimensional results illustrated mountain waves were produced with trapping at the critical layer situated approximately 1 km above ground level (AGL). Wave breaking was observed to have caused atmospheric instability and overturning, forcing warmer air down to lower levels in the lee of the mountain. Strong downslope winds were also observed in the simulations. This case study enables the accuracy of identifying and forecast turbulence to be improved, which is of great importance to the aviation industry. The case study methods and results can be further applied to other regions and investigations involving aircraft.

Key words: breaking, complex topography, critical layer, forecasting, instability, mountain waves, severe turbulence, terrain induced turbulence Email: t.oaklev@ugrad.unimelb.edu.au

Session 6 Meteorology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

THE UNUSUAL CYCLONE "DONALD": LARGE SCALE PERSPECTIVES AND COMPARISON WITH THE FIRST SOUTH ATLANTIC HURRICANE L. A . G a r d e \ A . B. Pezza^ a n d J. A . T . Bye^ ^School of Earth Sciences, University of Melbourne, Parkville, Victoria, Australia as it displayed TC properties such as an eye, an upper level warm core, and in addition, low level wind maximums exceeding 50kts. The purpose of this study is to explore the meteorological characteristics of the large scale circulation associated with the cyclogenesis of this unusual system, paying particular attention to large scale features such as blocking activity and environmental windshear in the Australian region. Using 2.5° re-analysis and 0.125° BoM LAPS resolution datasets, the study attempts to understand the mechanisms associated with hybrid systems and tropical and extratropical transitions. An investigation has also conducted to determine if Donald could have had hybrid properties of both tropical and extratropical origin similar to the "First South Atlantic hurricane Catarina" phenomenon of March 2004. This analysis assists in identifying hybrid systems, which is of significant importance to communities located along threatened coastlines whilst enabling Meteorologist to provide appropriate warnings for such unusual systems.

During the period of March 4-8 2001, an unusual intense low-pressure system was observed to develop in the Tasman Sea near SOS 151E and slowly move northwest towards the northern NSW coast while intensifying. Analysis of the system produced an erratic track, which saw the system make landfall at Byron Bay NSW with a central minimum pressure of 992hPa. Sea Surface Temperatures (SST's) during this time period were observed to approach the empirically derived hurricane threshold of 26.5°C. Land based observations measured via Automatic Weather Stations (AWS) along the northern NSW coast recorded 10-min average winds exceeding 50kts, qualifying this system as an equivalent Category 2 Tropical Cyclone (TC). Located 50km south of landfall, Evans Head RAAF base recorded 153mm of rain in a 24 hour period in addition to measured wind gusts of 139km/h, with a mean wind speed of lOOkm/h. Some researchers informally referred to this system as "Donald", and a stimulated discussion was generated amongst Meteorologists as to whether this system should be classified as a TC

Key words: low-pressure system, tropical cyclone, hybrid systems, extatropical transition, tropical transition, cyclogenesis, warm core, environmental windshear, blocking activity Email: l.qarde@uqrad.unimelb.edu.au

Session 6 Meteorology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

UNDERSTANDING THE INCONSISTENCIES BETWEEN TWO DIFFERENT SOURCES OF MORTON'S AAET DATA FOR RANGER URANIUM MINE SITE, NORTHERN TERRITORY, AUSTRALIA M. Kabir\ G. M. Mudd^ and A. R. Ladson^ ^Institute for Sustainable Water Resources, Department of Civil Engineering, Monash University, Australia

To understand the relationship between the climate and groundwater levels in shallow unconfined aquifers, the historical data of rainfall and evapotranspiration (Morton's Actual Areal Evapotranspiration, AAET) and groundwater level data have been analysed. The site studied is the Ranger uranium mine, Northern Territory, Australia. Of the three main hydrologic variables, rainfall and groundwater level data are measured whereas evapotranspiration data are estimated. As the process of evapotranspiration estimates involves a lot of climatic variables, which vary significantly in time and space, there was a need to investigate the available methods and sources for estimating evapotranspiration (ET) data. The two principal sources of ET data are the Bureau of Meteorology ET map data and SILO Patched Point Data (PPD). The ET map of Australia is developed based on long-term averages (1961-1990) for the monthly values of a year. The SILO data provides daily values of estimated evapotranspiration. We select the AAET from both sources for our analysis. We estimate the monthly AAET of SILO data by summing up the daily values, with SILO data obtained in 2006 being for the period 1980-2005. Both of these sources have used the Morton equations in the estimation of AAET. We compare the annual AAET of these two sources in view of their performance in the annual water balance for the Ranger site. The average annual Morton's AAET from SILO is 1414 mm whereas the AAET for the same site from the ET map gives 1064 him. The ET map is based on the period of 1961 to 1990. Therefore

we find the average annual Morton's AAET from SILO 2006 source for the Jabiru site for the same period (1961 to 1990) also and it is 1361 mm. Thus the SILO data source of Morton's AAET is consistently higher then the ET map. The consideration of annual runoff in the water balance fits better with ET map data in comparison to SILO; ie. Runoff (514 mm) + AAET (1064 mm) = Rain (1498). Though both are ideally supposed to be the same estimates, the reason for inequality may be attributed to the fact that after estimation of AAET, the values of map were adjusted for the regional water balance by the investigators. Therefore two sets of conceptual models need to be considered to demonstrate the validity of both of the AAET estimates. For AAET estimates of SILO, we should consider (Rain = wet season AAET + runoff) and (runoff = dry season AAET). That means, the runoff is a sink for wet season rainfall and source for dry season evapotranspiration in the form of soil moisture. This is valid where the catchments under consideration generates and absorbs the runoff within itself. For AAET estimates from ET map data we should consider Rain = Runoff + AAET. This is valid when the runoff is a one-way flow; it is generated from rainfall and not absorbed within the catchments boundary for recycling in dry season. In summary, it is critical to check and crosscorrelate AAET data for hydrologic catchments, especially in the context of regional water balances.

Key words: Morton's AAET, SILO Patched Point Data, evapotranspiration map data, Ranger uranium mine Email: Mobashwera.Kabir@enq.monash.edu.au

Session 7 Geodynamics and Economic Geology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

GEODYNAMIC EVOLUTION OF A PROTEROZOIC CRUSTAL SCALE SHEAR ZONE: CONSTRAINTS FROM DEFORMATION, METAMORPHISM AND GEOCHEMISTRY R. J. Armit\ P. G. Betts^ and B. F. Schaefer^ ^School of Geosciences, Monash University, VIC, 3800, Australia The Mount Painter Inlier is cut by the steeply west dipping Paralana Fault, interpreted as a crustalscale shear zone. This shear zone juxtaposes Palaeoproterozoic metasedinnents from the Mesoproterozoic (ca. 1575 Ma) Mount Neill Massif. Syn to post magmatic ductile sinistral shearing is recorded within the Mt Neill Massif, as a near vertical fabric. This foliation is comparable both in terms of metamorphic grade and orientation to the regionally observed S3 and may be attributed to waning stages of the Olarian Orogeny. Regional S3 overprints high grade metamorphic assemblages (sillimanite + garnet) S1 fabrics and retrograde (muscovite + biotite) S2 foliations. Post D3 thrusting (localised flower structures) and ductile dextral shearing (local mylonites) are overprinted by late sinistral brittle faulting. This results in a wide (100 metres) zone of mineralised breccia along the fault and the truncation, wrapping and offset of mineral fabrics within the Proterozoic metasediments and igneous suite. Hence the Paralana Fault records a long evolution at varying crustal depths. Late (Delamerian) N-S shortening

followed by orogenic collapse produces 2 orthogonal crenulation cleavages. eNd values for the Mount Neill Massif A-type granites range between -3.24 and -2.18 with Si02 content of 70-75%. Hiltaba A-types (Gawler Craton) with similar silica content (Nutys subdomain) give comparable £Nd values between -3.74 and 2.51. The Mount Angelay igneous complex (Cloncurry, Qld) also has comparable eNd values. U-Pb ages and populations of detrital zircons within the metasediments provide indications of a predominantly Gawler provenance. Positive Yttrium anomalies within the Mount Neill Massif suggests a high degree of partial melting indicative of a enriched melt source region. Radiometrics indicate high concentrations of radiogenic elements (U, Th, K) within the region which could supply the high heat flow required for high levels of partial melt and REE enrichment. This REE enriched signature resembles Olarian A-type granites.

Key words: Mt Neill Massif, Mount Painter Inlier, Crustal-scale she'ar zone longevity, Yttrium positive anomalies, LA-ICP-MS U-Pb detrital zircon dating Email: riarm2@student.monash.edu.au

Session 7 Geodynamics and Economic Geology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

DEPOSITIONAL HISTORY OF THE CORUNNA CONGLOMERATE AND ITS STRATIGRAPHIC RELATIONSHIP TO THE GAWLER RANGE VOLCANICS, GAWLER CRATON, SOUTH AUSTRALIA L. M. Morgan\ P. G. Betts^ and B. F. Schaefer^ ^School of Geosciences, Monash University, Clayton, Victoria, Australia

The Corunna Conglomerate, located in Gawler Craton, South Australia, is interpreted as Palaeoto Mesoproterozoic in age, synchronous with the nearby Gawler Range Volcanics (GRV). The GRV have been dated at -1592 Ma (U-Pb SHRIMP). There are two main exposures of the Corunna Conglomerate; Baxter Hills and Uno Range. The base of the exposed section at Baxter Hills comprises the Lower Green Sandstone (LGS) which coarsens into the Red Conglomerate (RC). Stratigraphically above an angular unconformity is the White Conglomerate (WC) fining into the Upper Green Sandstone (UGS). The Purple Siltstone (PS) and the White Sandstone (WS) are almost flat lying and unconformably overlie openly folded WC. Baxter Hills deposits are higher energy overall with larger clasts sizes in comparison to Uno. The LGS and RC contain clasts of quartzite, jaspilite, and iron-stone in a ferruginous sandstone matrix at Baxter Hills, while Uno Range RC contains predominantly clasts of quartzite and rare clasts

of iron-stone. The WC is clast supported with boulder to granule clasts of quartzite. The UGS is clean white to green quartzite with ferruginous layers defining cross-bedding. Sedimentary structures indicate an alluvial fan system. The inner fan is preserved by high energy reworked conglomerates and planar laminations at Baxter, with a distal braided river system and abundant cross-bedding at Uno. Paleocurrent data preserve an initial unimodal source for LGS at Baxter Hills continuing through the RC with greater variation in the source direction. Uno Range RC shows a polymodal current pattern with dominant southern flow. Baxter Hills WC data indicates variation of current directions constrained to southern source flow. UGS data from Uno Range has a prominently bimodal current source from South-East and North-West. Provenance is unlikely to be GRV derived due to lack of volcanic clasts and paleocurrent data does not indicate a northern source.

Key words: Gawler Craton, Paleocurrent directions, Corunna Conglomerate Email: lmmor1@student.monash.edu.au

Session 7 Geodynamics and Economic Geology

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

THE NATURE OF GOLD MINERALISATION IN THE WOODS POINT - WALHALLA GOLDFIELDS, EASTERN VICTORIA M. Hough\ F. P. Bierlein^ L Ailleres\ S. Hutchin^ and A. Seymon'^ ^School of Geosciences, Monash University VIC 3800 ^Centre for Exploration Targeting, University of Western Australia WA 6000 ^Goldstar Resources, Rawson VIC 3825 "^Geoscience Victoria, GPO Box 440, Melbourne VIC 3001 highlighted the increased levels of visible gold, and also the presence of disseminated gold, especially along dyke margins. Auriferous laminated veins are more common in the sediment-hosted Cohen's Reef, whereas auriferous brecciated quartz veins are commonly associated with laminated veins in the dykehosted deposits such as Eureka and Tubal Cain, especially at depth. A number of hydrothermal phases are evident in all three deposits, from initial barren quartz or carbonate veins, to quartzcarbonate veins associated with sulphides, to later gold-rich quartz veins. The initial phases of hydrothermal activity formed the crack-seal laminated quartz-carbonate veins with minor sulphide and host rock selvages. The later hydrothermal events occurred at shallower levels under more cooler, brittle conditions, and are characterized by open space vein fill with vugs, brecciated quartz zones, and the highest gold values.

The Walhalla-Woods Point Goldfield in eastern Victoria, hosts anonnalously large deposits, and in this regard, the ten highest yielding deposits within the goldfield are either hosted within, or spatially associated with, intrusions of the Devonian Woods Point Dyke Swarm. This unique goldfield within Victoria allows the connparison of (i) western and eastern Victorian gold mineralization; (ii) sediment-hosted, dykeassociated and dyke-hosted gold mineralization; and (iii) structural and geochemical factors for gold mineralization. Three deposits near the historical township of Walhalla were selected for research as they differ in regards to host lithology - Cohen's Reef is sediment-hosted but dykeassociated, whereas Eureka and Tubal Cain are both dyke-hosted. Based on current research, favourable sites for gold mineralisation in the Walhalla-Wood's Point Goldfield are dyke-hosted quartz breccia zones. Historical production concentrated on visible gold within the shear-zone hosted laminated reef systems, although recent assay results have

Key words: orogenic gold. Western Lachlan Orogen, Devonian, Woods Point Dyke Swarm, Walhalla Synclinorium Email: Meqan.Houqh@sci.monash.edu.au

Poster Session

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

HYDROGEOLOGY & SALINITY PROCESSES MOUNT MERCER - ILLABAROOK AREA

THE

G. D. Mockunas^ ^Department of Geology, University of Ballarat, Victoria, Australia

The lllabarook area was identified in the Corangamite Salinity Action Plan (SAP) 2005 2008, as a target area for salinity management area on the basis that it contributed salt to the Waody Yaloak River. Investigations in the Mount Mercer - lllabarook area south of Ballarat aimed at identifying the near surface processes causing salinity, and contributing salt to the major tributaries of the Woady Yaloak river system. The research will assist in determining possible management options by which to target the increasing salinity problem. Three research sites across the lllabarook salinity target area were selected that represent typical salinity occurrences. The salinity processes at these sites will be compared to the original hydrological model developed in the Corangamite SAP. The research involves the development of hypothetical hydrological models representative of the observed salinity processes; an EM 38 geophysical survey to

delineate salinity processes in the near surface; soil analysis for salinity (using Electrical Conductivity (EC)), pH and textural properties; surface water monitoring for EC and pH in the major drainage systems within the lllabarook target area; and photogrammetric analysis of historical aerial photographs to monitor land-use and surface salinity over time. The results of the soil analysis and geophysical surveys at each site has provided high-resolution details of the near surface salinity processes, and identified regions of high salt concentrations. These compare well with the historical data gained from the aerial photographs. Surface water analysis has shown both spatial and temporal variations in stream salt loads across the lllabarook target area over the past two years of monitoring. The identification of the salinity processes and the large-scale mapping will assist in targetting salinity management options and mitigate the off-site salinity hazards.

Key words: salinity processes, geophysical survey, soil analysis, large-scale mapping Email: gmockunas@.students.ballarat.edu.au

Poster Session

Victorian Universities Earth and Environnnental Sciences Conference La Trobe University, September 25, 2007

A PLIOCENE SEA SURFACE TEMPERATURE RECONSTRUCTION FOR SOUTHEASTERN AUSTRALIA USING THE MODERN ANALOGUE TECHNIQUE C . L . L \ \ S . J . G a l l a g h e r ^ a n d J . Bye^ ^School of Earth Sciences, University of Melbourne, Parkville, Victoria 3010, Australia

census counts from ditch cuttings from exploration well Mackerel 1, also in the Gippsland Basin (38°28'48.45, 148^2r30.56). Using the same MAT, SSTcooi and SSTwarm gave estimates of 1.7 ®C and 0.4 °C warmer than present day respectively. Though there are differences in magnitude of temperature reconstructions from the two types of cores, the trends in S S T variation and fluctuations in planktonic foraminiferal assemblages show similar variability, particularly the evidence of upwelling events throughout the Pliocene, through the intermittent increases in abundance of Globigerina bulloides. Results from this study seem to concur with other studies on the mechanism for Pliocene warmth that an enhanced meridional heat flow, perhaps in this instance, an enhanced East Australia Current, operated during the mid-late Pliocene, bringing warmer tropical waters from the Coral Sea down into the Gippsland Basin. This contributed to the estimated 2-3°C increase in S S T at this site throughout much of the Pliocene.

The Pliocene (5.3 - 1,8 Ma) was the last epoch during which earth's climate was significantly warmer than the present day, while climatic boundary conditions were essentially the same. Planktonic foraminifera were picked from sidewall cores from exploration well Flounder 5 located in the Gippsland Basin, Southeastern Australia (SS'ÎS'IQ.S, 148^27') for a S e a Surface Temperature (SST) reconstruction using the Modern Analogue Technique (MAT). Census counts of the planktonic foraminifera were compared to 1274 coretops from the M A R G O database using the Squared Chord Dissimilarity measure. Weighted averages of SSTcooi and SSTârm from the 10 closest analogues of each sample were used to give SST estimates. Reconstructions show that S S T fluctuatfons throughout the Middle to Late Pliocene were relatively stable, with SSTcooi 3.1 and SSTârm 2.3 warmer than present day values. Seasonality during the Pliocene at this site was 0.6 ° less than present day seasonality. For comparison only, Pliocene S S T estimates were reconstructed from planktonic foraminifera!

Key words: planktonic foraminifera, Modern Analogue Technique, S e a Surface Temperature, Pliocene, palaeoceanography Email: c.li2@pgrad.unimelb.edu.au

Poster Session

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

SOLUBLE AND MINERALIZABLE CARBON FROM ORGANIC AMENDMENTS INFLUENCE AGGREGATION IN HIGH CLAY, SODIC SOIL G. J. Clark\ C. Tang^ and P. W. G. Sale^ ^Department of Agricultural Sciences, La Trobe University, Victoria 3086

Subsoil constraints are connmon problems that limit crop production in Australia. We are interested in improving crop production on soils with dense clay subsoils that are highly sodic. As these subsoils are low in organic matter we postulated that subsoil structure may be improved with large inputs of organic matter amendments. A study was therefore undertaken to gain an understanding of the way in which organic matter influences the aggregation of a sodic subsoil (ESP = 20) comprising 30% sand, 9% silt and 60% clay. The study involved the addition of organic amendments with differing C:N ratios, as well as gypsum, to the subsoil at the rate of 1% w/w. The soil was then incubated for 174 days at 25°C. Wheat and lucerne amendments significantly increased stable macroaggregates (> 2 mm) within 14 days. After 174 days wheat-, canola-.

chickpea- and chicken manure- amended soils all showed an increased proportion of macroaggregates with a corresponding decline in microaggregates (< 0.25 mm). In contrast lucerne-amended soil showed a decline in macroaggregates by day 174. The formation of macroaggregates was moderately correlated, until day 14, with cumulative soil respiration (R^ = 0.76). This correlation weakened by day 174 (R^ = 0.58). In addition the ESP was reduced by the addition of the residues of wheat, canola, chickpea and the gypsum and chicken manure amendments. The proposed model of aggregation appears to be initially driven by soluble organic carbon while long term aggregate stability may be more dependent on the less mineralizable carbon from organic amendments.

Key words: subsoil constraints, organic amendments, gypsum Email: gidark@students.latrobe.edu.au

Poster Session

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

STRONTIUM ISOTOPES AND RADIOCARBON DATING HELP TO DETERMINE GROUNDWATER FLOWPATHS IN THE UPPER LODDON CATCHMENT, CENTRAL VICTORIA S. K. Hagerty\ J. A. Webb^ and G. E. Jacobsen^ ^Department of Environmental Geoscience, La Trobe University, Bundoora, Victoria, Australia ^Institute for Environmental Research, ANSTO, Lucas Heights, NSW, Australia

Sr isotopes and radiocarbon dating have been used to delineate flowpaths and determine interactions between the basalt and deep lead aquifers in the study area. Low ®^Sr/®®Sr ratios and relatively young radiocarbon dates confirm that both aquifers are recharged through scoria cones at volcanic eruption points. The ratios of basalt groundwater in the study area vary widely (0.704647 to 0.714296) and form two chemically distinct groups: this is due to upflowing deep lead groundwater where faulting has significantly reduced the volume of the deep lead aquifer. The radiocarbon dating also shows that flow paths in the basalt aquifer are complex since ages do not always increase downflow. One anomalously old ^"^C date supports other hydrogeological evidence that suggests groundwater in the deep lead is trapped upflow of horsts created by the ENE Cainozoic faults.

Salinisation and water scarcity threaten surface and groundwater supplies in the in the Upper Loddon catchnnent, central Victoria. A detailed hydrogeological / hydrogeochemical study of the catchnnent was carried out in order to identify processes affecting water and salt storage and movement, to inform local water and land managers. The basement aquifer in the Upper Loddon consists of Ordovician bedrock; in the Early Tertiary this was incised by a palaeodrainage system that was then infilled by fining upwards sediments (sands/gravels to clays/silts), creating the deep leads. ENEA/VSW trending contemporaneous faults disrupted deposition of the sediments, creating alternating areas of thick and thin to absent deep lead sediments. Covering the deep leads are several different basalt flows of the Pliocene to Pleistocene Newer Volcanics; clay-rich soils separate some of the flows.

Key words: deep leads, isotopic tracers, radiocarbon dating, Sr isotopes, aquifer interactions Email: skhaqertv@students.latrobe.edu.au

Poster Session

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

THE EFFECT OF NITROGEN FORM, DCD AND EDDS ON ZINC PHYTOEXTRACTION BY THLASPI CAERULESCENS, LUPINUS ALBUS AND L PILOSUS A. C. Monsant\ C. Tang^ and A. J. M Baker^ ^Department of Agricultural Sciences, La Trobe University, Bundoora, Vic. 3086 ^School of Botany, University of Melbourne, Parkville, Vic. 3010

Nitrogen fertilization in the ammonium (NH/) form promotes rhizosphere acidification which increases the soluble Zn concentration in Zn contaminated soils. This may enhance phytoextraction efficiency as compared to fertilization with other forms of nitrogen. This glasshouse study examined the effect of nitrogen form on Zn phytoextraction in Thiaspi caerulescens (a Zn hyperaccumulator), Lupinus albus (a Zn accumulator) and Lupinus pilosus (untested for Zn accumulation). The plants were grown in a Zn-contaminated soil (total Zn 250 mg/kg soil, pHw 5.7) with the nitrogen fertilisers (NH4)2S04 or Ca(N03)2 or urea. The N H / form was maintained by applying the nitrification inhibitor DCD. A biodegradable chelator EDDS was included for comparison. Results showed that the rhizosphere of all species with (NH4)2S04 treatments was considerably more acidic than the Ca(N03)2 or urea treatments. Interestingly this caused less Zn to be taken up, and for T. caerulescens this resulted in a trend of increasing Zn shoot concentration with increasing pH (R^ = 0.54). This suggests that for this species Zn solubility is not as important as root physiology for Zn uptake. Surprisingly, Ca concentration in the

shoots significantly correlated with rhizosphere pH and Zn concentration in the shoots (both R^ = 0.63), which suggests the involvement of Ca in Zn uptake mechanisms. In addition, T. caerulescens biomass and Zn extraction was increased with Ca(N03)2 compared to the other treatments. EDDS did enhance zinc uptake by T. caerulescens but a decrease in biomass occurred, resulting in low Zn phytoextraction per plant. DCD + (NH4)2S04 did not differ from (NH4)2S04 for all species, possibly because nitrification was already inhibited in the acidic soil. The variation between Lupinus spp. was greater than the variation between treatments due to unforseen variable response by plant individuals due to zinc toxicity. L. pilosus had significantly higher zinc concentrations but extracted less zinc than L. albus due to its lower biomass. We conclude that for T. caerulescens acidification of the rhizosphere by (NH4)2S04 did not increase its Zn uptake or phytoextraction efficiency. Ca(N03)2 fertilisation enhanced the phytoextraction of zinc more than (NH4)2S04, or the chelator EDDS in the acid soil. Ca may be involved in the Zn uptake mechanism. L. albus was a better Zn phytoextractant than L pilosus.

Key words: phytoremediation, zinc, Thiaspi caerulescens, Lupinus albus, Lupinus pilosus, nitrogen form, EDDS Email: ac4monsant@students.latrobe.edu.au

Poster Session

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

LAKE WATER-MASS BALANCE MODELLING AS A PREDICTIVE TOOL FOR WATER QUALITY MANAGEMENT M. Raiber^ a n d J . A . Webb^ ^Departnnent of Environmental Science, La Trobe University, Bundoora, Victoria, Australia

Lake Bolac, a 13.1 km^ natural shallow lake with a median depth of 1.97 m, was selected for a detailed water mass-balance and salt budget study as an example of the numerous shallow water bodies spread across the basalt plains of western Victoria. As a consequence of the severe drought over the last 10 years in southern Australia, the water level of Lake Bolac has continuously dropped, resulting in lake salinities well in excess of seawater. To understand the major controls on the lake water levels and lake salinities, a detailed spreadsheet-based water mass-balance model designed to examine water fluxes to and from Lake Bolac was formulated. The model incorporates all major water sinks (evaporation, groundwater outflow and surface water outflow) and sources (precipitation, groundwater inflow and surface water inflow) and determines their relative contribution to the lake water budget on a monthly basis. To forecast the response of the lake levels and lake salinities under different climatic scenarios, the lake water budget model was run with two synthetic data sets. The first data set predicts the

length of time required for the recovery of the lake water levels and lake salinities to predrought levels, using evaporation and precipitation data from wetter than average conditions, and modeled streamflow resulting from this climatic regime. The second data set assumes the continuation of dry conditions, and uses evaporation and precipitation data from exceptionally dry years and the modeled streamflow generated under such climatic conditions. The lake water mass-balance and the predictive modelling forecast a fast recovery of the lake level to pre-drought water levels and salinities within less than one year under wetter than average climatic conditions. A continuation of drought conditions, on the other hand, would result in the drying out of Lake Bolac within one year. The results of this study are an integral part of the current assessment of the water quality issues related to Lake Bolac and will assist further decision making with regards to the longterm fate and management of the lake.

Key words: lake water mass-balance modelling, salinity, drought, basalt plains, western Victoria Email: mraiber@students.latrobe.edu.au

Poster Session

Victorian Universities Eartli and Environmental Sciences Conference La Trobe University, September 25, 2007

PHOSPHORUS STRATIFICATION UNDER DIFFERENT TILLAGE SYSTEMS IN THREE CONTRASTING VICTORIAN SOILS D. T. V u \ C. Tang^ and R. Armstrong^ ^Departnnent of Agricultural Sciences, La Trobe University, Australia ^Department of Primary Industries, Victoria, Australia

Major changes have occurred in the management of cropping systems in recent decades. These changes include a move towards continuous cropping and an increasing adoption of reduced tillage practices. However there has been little change in the management of nutrients, especially P fertilisers. Current nutrient management strategies take little account of the various agro-ecological zones in which grain crops are grown in Victoria, despite major differences in soil types, rainfall and the range of crops/pastures grown. This study investigated the effects of tillage and crop rotations on stratification and transformation of P in soil profiles in different agro-ecological zones. Soil samples were collected from 3 agro-ecological zones: Horsham (Vertosol; rainfall =420mm), Walpeup (Calcarosol; rainfall=325 mm), and Rutherglen (Chromosol; rainfall =650 mm). Soil samples of

0-5, 5-10 cm depths were sequentially analysed for P fractions as modified Medley's method and whilst soil samples of 10-20, 20-30, 30-40 cm depths were analysed for total P, Olsen-P, ResinP. Following a long-term application (9 to 25 years) of P fertilisers, P accumulation occurred in the surface soil (0-5 and 5-10 cm). However, soil type and rainfall strongly influenced both the total amount of P accumulated and the distribution of this P between different soil pools. In the calcareous soil, the applied P was distributed evenly between all P pools. In contrast, the applied P tended to be transformed into nonlabile P pools in Vertosol and Chromosol. Tillage had significant effects on the distribution of P in soil profiles. The implications of these findings for nutrient management strategies of Victorian grain production systems are discussed.

Key words: phosphorus stratification, phosphorus fractions, tillage systems Email: dtvu@students.latrobe.edu.au

Poster Session

Victorian Universities Earth and Environmental Sciences Conference La Trobe University, September 25, 2007

EIGHT YEARS OF DISTICHLIS SPICATA GROWTH IMPROVES SOIL PROPERTIES IN A SALINE DISCHARGE ZONE M. Sargeant\ C. Tang^ and P. Sale^ ^Department of Agricultural Sciences, La Trobe University, Bundoora, Victoria, Australia Saline discharge sites are generally seen as degraded environnnents, both in a chemical and physical sense. These sites contain high concentrations of salts within the soil, and are commonly waterlogged, which creates a very hostile environment for plant growth. Distichlis spicata (NyPa Forage) is a C4 halophytic pasture species that is able to grow productively in these environments and has been used on a trial basis for approximately 10 years at Wickepin, Western Australia. Over this time, the land manager has observed improvements in the soil appearance where D. spicata was planted. To test the hypothesis that D. spicata improves the soil chemical and physical properties, comprehensive soil sampling was undertaken at the site and the samples were subject to analysis. This paper reports preliminary results of this work. Eight years of D. spicata growth significantly increased the saturated hydraulic conductivity of the topsoil. The greatest increase can be found after 8 years of growth, with an increase from approximately 0.5 cm/hr to 7.5 cm/hr in the top 06 cm. There were also increases with 8 years of D. spicata growth compared to the control soil at all depths, with the size of the increase

decreasing with depth. Two years of growth of D. spicata resulted in a small increase in conductivity at the 0-6 cm depth compared to 8 years of D. spicata growth. Eight years of D. spicata growth significantly improved the stability of the soil aggregates in the top 10 cm of the soil. Approximately 75 % of the aggregates remained larger than 2 mm in diameter after 5 minutes of wet sieving. This improvement in stability did not occur where D. spicata had been growing for 2 years. This improvement in aggregate stability was limited to the top 0-10 cm of soil, with no significant differences between D. spicata treatments for aggregate stability at the 10-20, 20-30 and 30-50 cm depths. Soil carbon and nitrogen concentrations also increased where D. spicata had been growing for 8 years, with the greatest increases found in the top soil. The results indicate that improvements in the soil physical properties occur where D. spicata is grown in saline discharge zones. Further analysis will be conducted to determine if this also extends to soil chemical properties.

Key words: saturated hydraulic conductivity, water stable aggregates, soil fertility, saltland pasture, Distichlis spicata, NyPa Forage, halophyte Email: sarqeantmark@gmail.com

Poster Session

Victorian Universities Earth and Environnfiental Sciences Conference La Trobe University, September 25, 2007

SALT PRIMING IMPROVES THE ESTABLISHMENT OF DISTICHLIS SPICATA IN SALINE CONDITIONS M. Sargeant\ P. Sale^ and C. Tang^ ^Department of Agricultural Sciences, La Trobe University, Bundoora, Victoria, Australia Salinity has long been part of the Australian landscape as early explorers reported that river water was too saline to drink. However, large areas of agricultural land have become progressively saline since European settlement, partly due to 'leaky' agricultural systems that do not utilize all the rainfall. Most land managers concede that salinised land has been lost for agriculture, yet there is now increased interest in developing halophytic plant systems to productively use saline land. Distichlis spicata (NyPa Forage) is a male clone C4 halophytic grass that has been selected to grow in wet saline soil. Its C4 characteristics mean that most growth occurs during the summer months. It therefore has the potential to provide out-ofseason forage in the dry summer months in southern Australia. However, establishment of vegetative plants/cuttings in wet discharges sites has been problematic due presumably to the hostile saline conditions during the establishment phase. This experiment tested the hypothesis that salt priming would improve the establishment of D. spicata plants when established into saline conditions. The experiment was conducted in a glasshouse at La Trobe University, Bundoora Victoria (37°42'S, 145°02'E), and commenced in January and completed in June 2005. The experiment was set up as a randomised block design with the factorial combination of 3 pretreatments and 4 treatments of salinity. Pretreatment consisted of 3 levels of salinity, 0, 2 & 4 g NaCI/kg sand, in large plastic boxes filled with fine white quartz sand with basal nutrients incorporated. Rooted cuttings of D. spicata were allowed to establish for 2 weeks before NaCI was added to the respective pre-treatments. After 36

days of pre-treatment, three plants were transplanted into 200 mm pots filled with fine white quartz sand amended with basal nutrients, to which 4 salt treatments were applied, including 0, 2, 4 & 8 g NaCI/kg sand. A constant watertable of 0.5 cm was maintained by placing glass bottles filled with deionised water upside down into PVC tubes. Plants were grown for 63 days and then assessed for survival and shoot dry matter. The main salt treatments had a more marked effect on survival than did salt pre-treatment. Increasing the post-transplanting salt level decreased the survival, with the highest level of 8 g NaCI/kg sand restricting survival to less than 1 plant per pot. The new growth following transplanting was affected by treatments, resulting in a highly significant interaction between pre- and posttransplanted salinity levels (p<0.01) on dry matter production at harvest. There was nearly a 6-fold increase in dry matter production of the plants pre-treated with 4 g NaCI/kg sand compared with plants pre-treated with 0 and 2 g NaCI/kg sand when grown in 2 g NaCI/kg sand. However, when plants were pre-treated with 4 g NaCI/kg sand and then transplanted into sand containing no salt, they produced approximately half the dry matter of plants that had been pre-treated with nil salt. The treatment of 8 g NaCI/kg resulted in minimal dry matter accumulation irrespective of the pre-transplanting salt exposure. This suggests that salt-priming will be a useful tool for establishing D. spicata transplants in saline environments. Salt priming was shown to increase plant survival and shoot dry matter production.

Key words: salt priming, vegetative establishment, Distichlis spicata, NyPa forage, saltland pasture, halophyte Email: sarqeantmark@qmail.com

INDEX OF PRIMARY AUTHORS

Ashcroft, L

Armit, R. J.

Kabir, M.

L B Brick, R. A

Li, C. L

24 M

Monsant, A. C.

Clark, G. J

Meneghini, B.

Coady, K.

Mockunas, G. D

Morgan, L. M.

E Ely, K. S.

Edwards, L

Oakley, T. W. N

Ryan, M.

Raiber, M.

22,38

F Fussell, M

G Ganter, C. J

Garde, L. A

Seller, C.

Stafford, J. L. P

Sargeant, M

40,41

H Hasson, A.

Hart, C.V

Hough, M.

Vu, D. T.

Hagerty, S. K

Y J Jakaica, S.

Yihdego, Y. 18