Geological Society of Australia
ABSTRACTS Number 8
PERMIAN GEOLOGY OF QUEENSLAND
ISSN 0729 011X ISBN 0 909869 22 7
G e o l o g i c a l Society of Australia I n c .
ABSTRACTS Number 8
PERMIAN GEOLOGY OF QUEENSLAND
A b s t r a c t s of a Symposium held by the Queensland Division in conjunction with the G e o l o g i c a l Survey of Queensland in B r i s b a n e , 14-16 July 1982
ISSN 0729-01IX ISBN 0-909869-22-7
1. CONTENTS Page SYMPOSIUM PROGRAM
PERMIAN GEOLOGY OF QUEENSLAND
1.
C.G. Murray
10
ENERGY RESOURCES
12
PETROLEUM EXPLORATION - HISTORY AND FUTURE TRENDS M.A. Randal
13
PERMIAN GEOLOGY OF THE COOPER BASIN M„ Zwigulis
13
COOPER BASIN PETROLEUM - EXPLORATION AND DEVELOPMENT J. Armstrong
14
RAPID EVALUATION OF ORGANIC MATURATION FROM HEAD SPACE GAS ANALYSIS - APPLICATIONS IN THE DENSION TROUGH AND COOPER BASIN C.J. Boreham
15
THE APPLICATION OF COAL PETROLOGY TO OIL EXPLORATION J.W. Beeston 2.
ECONOMICS AND ENGINEERING
15 16
EVALUATION OF COAL PROPERTIES FOR OPTIMUM ECONOMIC DEVELOPMENT AND UTILIZATION OF THE COALS IN THE RANGAL COAL MEASURES AT CURRAGH NORTH OF BLACKWATER, CENTRAL QUEENSLAND D. Svenson & M.S. Peterson
17
THE INFLUENCE OF STRUCTURE ON THE DEVELOPMENT OF UNDERGROUND COAL MINES IN THE WESTERN BOWEN BASIN D.M. Devey
18
GEOTECHNICAL CONDITIONS AFFECTING STRIP COAL MINING IN THE BOWEN BASIN A.L. Davies
19
GEOLOGICAL EVALUATION OF THE THEODORE NORTH COALFIELD B;A. Coxhead & B.A. Brandt
19
2. Pr>no 3.
PALAEONTOLOGY
20
REVIEW OF THE TIME FRAME FOR THE PERMIAN OF QUEENSLAND C. B. Foster
2"
THE SEQUENCE OF FAUNAS IN THE TIVERTON FORMATION, NORTHERN BOWEN BASIN J.B. Waterhouse, D. Briggs & S. Parfrey
21
BIOSTRATIGRAPHIC APPRAISAL OF PERMIAN FORAMINIFERA FROM THE DENISON TROUGH (BOWEN BASIN) V. Palmieri
22
A PERMIAN PALYNOSTRATIGRAPHY FOR QUEENSLAND P.L. Price
22
THE PALYNOSTRATIGRAPHY OF THE PERMO-CARBONIFEROUS OF THE GALILEE BASIN, QUEENSLAND G.D. Powis
23
PALYNOSTRATIGRAPHIC COMPARISON BETWEEN THE ARCKARINGA BASIN IN SOUTH AUSTRALIA AND LATE PALAEOZOIC BASINS IN QUEENSLAND B.J. Cooper
24
THE ROLE OF THE GLOSSOPTERIS FLORA IN BIOSTRATIGRAPHY A PRELIMINARY ASSESSMENT J.F. Rigby
25
THE SEQUENCE OF PERMIAN ROCKS AND FAUNAS NEAR EXMOOR HOMESTEAD SOUTH OF COLLINSVILLE, NORTHERN BOWEN BASIN J.B. Waterhouse & J.S. Jell
26
THE PERMIAN BLENHEIM SUBGROUP OF THE BOWEN BASIN AND ITS TIME RELATIONSHIPS J.M. Dickins 4.
SEDIMENTOLOGY
27 28
SEDIMENTARY ENVIRONMENTS OF THE PEAK DOWNS COAL MINE, CENTRAL QUEENSLAND D. Archibald
29
DEPOSITIONAL ENVIRONMENTS IN THE RANGAL COAL MEASURES, SOUTHERN BOWEN BASIN C.W. Mallett
30
DEVELOPMENT OF PERMIAN COAL MEASURE LITHOFACIES AT GOONYELLA , QUEENSLAND D. Johnson CORRELATION BETWEEN THE COMET PLATFORM AND THE DENISON TROUGH, BOWEN BASIN A.T. Brakel PRELIMINARY SEISMIC INTERPRETATIONS IN THE TAROOM TROUGH C. Herbert THE ORIGIN OF PEBBLES IN MUDSTONES IN THE DENISON TROUGH, SOUTHWEST BOWEN BASIN J.J. Draper CARBONATE DIAGENESIS IN COAL MEASURES AT GOONYELLA, QUEENSLAND D.P. Johnson GEOPHYSICS SEISMIC REFLECTION TECHNIQUES APPLIED IN A BOWEN BASIN COALFIELD P.G. Harman A REVIEW OF REFLECTION SEISMIC PROSPECTING IN THE DENISON TROUGH (BOWEN BASIN) DURING 1960 TO 1982 R.J. Mollah & W.G. Mogg SEISMIC DATA ACQUISITION IN THE GALILEE BASIN T. White TITLE TO BE ANNOUNCED Middleton METALLIFEROUS DEPOSITS A REVIEW OF METALLIFEROUS MINERALISATION ASSOCIATED WITH PERMIAN ROCKS IN QUEENSLAND J.R. Kay THE NATURE OF TIN MINERALISING SYSTEMS WITHIN THE HERBERTON-MOUNT GARNET TINFIELD, QUEENSLAND P.J. Pollard & R.G. Taylor THE DRAKE MINERAL FIELD - A UNIQUE ENTITY IN EASTERN AUSTRALIA H. Herbert
SOME ASPECTS OF THE CLERMONT GOLDFIELD M.E. I'Ons A RE-ASSESSMENT OF THE CRACOW GOLDFIELD T. Hopwood THE MOUNT CHALMERS MINE AND ENVIRONMENT IN EASTERN QUEENSLAND - A KUROKO-STYLE VOLCANOGENIC SULPHIDE ENVIRONMENT A. Taube & P. van der Helder GOLD-SILVER MINERALISATION WITHIN THE DRAKE VOLCANICS OF NORTHEASTERN NEW SOUTH WALES AND SOUTHEASTERN QUEENSLAND H. Herbert MINERALOGICAL AND TEXTURAL MODIFICATIONS IN GRANITES ASSOCIATED WITH TIN MINERALISATION, HERBERTONMOUNT GARNET TINFIELD, QUEENSLAND P.J. Pollard, D. Milburn & R.G. Taylor TECTONICS POSSIBLE CONNECTIONS BETWEEN THE GYMPIE PROVINCE OF QUEENSLAND AND SIMILAR TERRANES IN NEW ZEALAND H.J. Harrington A PHOTOSTRUCTURAL CLASSIFICATION FOR PERMIAN COAL BASINS E.J. Heidecker & S.M. Veitch
5. SYMPOSIUM PROGRAM Wednesday 14 July 1982 ABEL SMITH LECTURE THEATRE 8:30
Registration SESSION CHAIRMAN - Dr G.W. Hofmann, Past Chairman, Queensland Division
9:30
Opening Ceremony Prof. B. Wilson, Vice Chancellor: Official Welcome Hon, I.J. Gibbs, Minister for Mines and Energy: Opening Address
10:00
C.G. Murray:
10:30
Morning Tea (Geological Laboratory, Steele Building)
Permian Geology of Queensland
SESSION CHAIRMAN - Mr R.J. Allen, Chief Government Geologist, Geological Survey of Queensland 11:00
M.A. Randal:
11:30
L.G. Elliot: Recent Gas Discoveries in the Denison Trough (Visual display of technical data)
Petroleum Exploration - History and Future Trends
12:00
M. Zwigulis:
12:30
Lunch (Optional at Cromwell College, Union Building Cafeteria or Staff Club)
Permian Geology of the Cooper Basin
SESSION CHAIRMAN - Mr R. Paten, Assistant General Manager (Petroleum), AAR Ltd 14:00
J. Armstrong: Cooper Basin Petroleum - Exploration and Development
14:30
C.J. Boreham: Rapid Evaluation of Organic Maturation from Head Space Gas Analysis - Applications in the Denison Trough and Cooper Basin
15:00
J.W. Beeston: The Application of Coal Petrology to Oil Exploration
15:30
Afternoon Tea SESSION CHAIRMAN - Prof. D. Rowlands, Head, Department of Mining & Metallurgical Engineering, University of Queensland
16:00
D. Svenson & M.S. Peterson: Evaluation of Coal Properties for Optimum Economic Development and Utilization of the Coals in the Rangal Coal Measures at Curragh north of Blackwater, central Queensland
16:30
D.M. Devey: The Influence of Structure on the Development of Underground Coal Mines in the western Bowen Basin
6. Wednesday 14 July 1982 ABEL SMITH LECTURE THEATRE (continued) 17:00
A.L. Davies: Geotechnical Conditions affecting Strip Coal Mining in the Bowen Basin
Wednesday 14 July 1982 LECTURE ROOM 26, STEELE BUILDING SESSION CHAIRMAN - Mr P.J.G. Fleming, Principal Geologist, Geological Survey of Queensland 11:00
C.B. Foster: Review of the Time Frame for the Permian of Queensland
11:30
J.B. Waterhouse, D. Briggs, & S. Parfrey: The Sequence of Faunas in the Tiverton Formation, northern Bowen Basin
12:00
V. Palmieri: Biostratigraphic Appraisal of Permian Foraminifera from the Denison Trough (Bowen Basin)
12:30
Lunch (Optional at Cromwell College, Union Building Cafeteria, or Staff Club) SESSION CHAIRMAN - Prof. J.B. Waterhouse, Department of Geology and Mineralogy, University of Queensland
14:00
P.L. Price:
14:30
G.D. Powis: The Palynostratigraphy of the Permo-Carboniferous of the Galilee Basin, Queensland
A Permian Palynostratigraphy for Queensland
15:00
B.J. Cooper: Palynostratigraphic Comparison between the Arckaringa Basin, South Australia, and Late Palaeozoic Basins in Queensland
15:30
Afternoon Tea SESSION CHAIRMAN - Dr R.W. Day, Assistant Chief Government Geologist, Geological Survey of Queensland
16:00
J.F. Rigby: The Role of the Glossopteris Flora in Biostratigraphy A Preliminary Assessment
16:30
J.B. Waterhouse & J.S. Jell: The Sequence of Permian Rocks and Faunas near Exmoor Homestead south of Collinsville, northern Bowen Basin
17:00
J.M. Dickins: The Permian Blenheim Sub-Group of the Bowen Basin and its Time Relationships
Thursday 15 July 1982 ABEL SMITH LECTURE THEATRE SESSION CHAIRMAN - Dr G. McClung, Senior Geologist, Offshore Oil NL 9:00
D. Archibald: Sedimentary Environments of the Peak Downs Coal Mine, central Queensland
7. Thursday 15 July 1982 ABEL SMITH LECTURE THEATRE
(continued)
9:30
C.W. Mallett: Depositional Environments in the Rangal Coal Measures, southern Bowen Basin
10:00
D. Johnson: Development of Permian Coal Measure LithofaciPr" at Goonyella, Queensland
10:30
Morning Tea SESSION CHAIRMAN - Dr P.J. Hawkins, Senior Geologist, Geological Survey of Queensland
11:00
A.T. Brakel: Correlation between the Comet Platform and the Denison Trough, Bowen Basin
11:30
C. Herbert: Preliminary Seismic Interpretations in the Taroom Trough
12:00
J.J. Draper: The Origin of Pebbles in Mudstones in the Denison Trough, southwest Bowen Basin
12:30
Lunch SESSION CHAIRMAN - Mr N. Rowlands, Exploration Manager, Utah Development Co.
14:00
D. Johnson: Carbonate Diagenesis in Coal Measures at Goonyella, Queensland
14:30
B.A. Coxhead & B.A. Brandt: Geological Evaluation of the Theodore North Coalfield
15:00
P.G. Harman: Seismic Reflection Techniques Applied in a Bowen Basin Coalfield
15:30
Afternoon Tea SESSION CHAIRMAN - Dr S. Hall, Senior Lecturer, Department of Geology and Mineralogy, University of Queensland
16:00
R.J. Mollah & W.G. Mogg: A Review of Reflection Seismic Prospecting in the Denison Trough (Bowen Basin) during 1960 to 1982
16:30
T. White:
Seismic Data Acquisition in the Galilee Basin
17:00
Middleton:
Title to be announced
Thursday 15 July 1982 LECTURE ROOM 26, STEELE BUILDING SESSION CHAIRMAN - Mr I.W. Morley, Principal, I.W. Morley & Associates 9:00
J.R. Kay: A Review of Metalliferous Mineralisation Associated with Permian Rocks in Queensland
9:30
P.J. Pollard & R.G. Taylor: The Nature of Tin Mineralising Systems within the Herberton-Mount Garnet Tinfield, Queensland
8. Thursday 15 July 1982 LECTURE ROOM 26, STEELE BUILDING
(continued)
10:00
H. Herbert: The Drake Mineral Field - A Unique Entity in eastern Australia
10:30
Morning Tea SESSION CHAIRMAN - Mr J.H. Brooks, Assistant Chief Government Geologist, Geological Survey of Queensland
11:00
M.E. I'Ons:
Some Aspects of the Clermont Goldfield
11:30 12:00
T. Hopwood: A Re-assessment of the Cracow Goldfield A. Taube & P. van der Helder: The Mount Chalmers Mine and Environment, eastern Queensland - A Kuroko-style Volcanogenic Sulphide Environment
12:30
Lunch SESSION CHAIRMAN - Mr E.M. Bennett, Exploration Manager, Mt Isa Mines Ltd
14:00
H. Herbert: Gold-silver Mineralisation within the Drake Volcanics of northeastern New South Wales and southeastern Queensland
14:30
P.J. Pollard, D. Milburn & R.G. Taylor: Mineralogical and Textural Modifications in Granites associated with Tin Mineralisation, Herberton-Mount Garnet Tinfield, Queensland
15:00
Discussion on Metalliferous Deposits
15:30
Afternoon Tea SESSION CHAIRMAN - Dr C.G. Murray, Principal Geologist, Geological Survey of Queensland
16:00
H.J. Harrington: Possible Connections between the Gympie Province of Queensland and similar Terranes in New Zealand
16:30
E.J. Heidecker & S.M. Veitch: for Permian Coal Basins
A Photostructural Classification
Friday 16 July 1982 ABEL SMITH LECTURE THEATRE SESSION CHAIRMAN - Mr J.W. Beestonf Chairman, Queensland Division 9:00
Summing Up by Topic Conveners
10:00
Closing Remarks Mr J.W. Beeston, Chairman,GSA Queensland Division Mr R.J. Allen, Chief Government Geologist, Geological Survey of Queensland
10:30
Busses leave for Zillmere
9. Friday 16 July 1982 (continued) 11:00
Inspection of drill cores from the Bowen Basin at the Core Library of the Queensland Department of Mines and Energy
14:00
Busses depart from Zillmere Core Library to return to the City (and/or Airport)
10. PERMIAN GEOLOGY OF QUEENSLAND Murray,
C'.C. / Geological Survey GPO Box 194, Brisbane,
of Queensland, 4001
The Permian System was proposed by Murchison in 1841 for rocks of the K u n g u r i a n , Kazanian and Tatarian series west of the Ural M o u n t a i n s . S u b s e q u e n t l y , the underlying Artinskian and Sakmarian series of the Urals were a d d e d . Biostratigraphic studies, based mainly on foraminifera, ammonites and brachiopods, have enabled worldwide correlations of Permian r o c k s , but as yet there is no international agreement on the positions of the Permian-Carboniferous and Permian-Triassic boundaries or on how and where these boundaries should be d e f i n e d . Initial investigations of the Permian rocks of eastern Australia concentrated on the coal measures of the Sydney (and Bowen) B a s i n . The age of these coal measures was the subject of a dispute between W . B . C l a r k e , w h o proposed a Palaeozoic (Carboniferous) age, based on the invertebrate fossils of the interbedded marine sequences, and F . M ' C o y , who insisted that the coal must be Mesozoic (Jurassic) because of its distinctive flora. Richard D a i n t r e e , in his geological map of Queensland and accompanying report of 1 8 7 2 , was the first geologist to clearly recognise the occurrence of both Palaeozoic and Mesozoic coal measures and to separate them on the basis of their different floras. Because of the difficulty of correlating the unusual late Palaeozoic faunas of eastern Australia with those of Europe, Robert Etheridge Jnr introduced the name Permo-Carboniferous in 1880 for the late Carboniferous and the entire Permian, and the term remained in general use for over 50 y e a r s . Since the 1930s, the Permian-Carboniferous boundary in eastern Australia has traditionally been placed at the first appearance of genera such as Eurydesma and Ingelarella, but this may not coincide with the base of the Permian in Europe and North America, which is defined by foraminiferal zones. Considerable progress has been made towards biostratigraphic zonation of the eastern Australian Permian from studies of plant microfossils and marine invertebrates, but further refinement is n e e d e d , particularly in the Late Permian. Permian sedimentation, volcanism and plutonism were widespread in Queensland. T w o large intracratonic basins, the Galilee Basin in the central part of Q u e e n s l a n d , and the Cooper Basin in the southwest, were the sites of intermittent freshwater sedimentation throughout the Permian. Extended periods of non-deposition occurred in the Early Permian in the Galilee Basin and in the Late Permian in the Cooper B a s i n . Late Permian coal measures developed in both basins in fluvial floodplain environments. The Bowen Basin formed along the boundary between the active New England Orogen to the east and the older craton to the w e s t . Initial sedimentation was thickest in the southwest in the Denison T r o u g h , and was both freshwater and m a r i n e . Deposition was dominantly marine until Late Permian t i m e . Coal swamps and deltaic sand sheets formed during regressions on a stable shelf along the northwestern margin of the basin. The final Late Permian regression commenced at the northern end of the b a s i n , so that coal measures in this area were coeval with marine sediments to the s o u t h . S u b s e q u e n t l y , coal measures formed throughout the b a s i n , and the locus of major subsidence shifted to the Taroom Trough in the southeast.
11. In North Queensland, granite emplacement into deformed Silurian-Devonian rocks of the former Hodgkinson Basin was continuous from the Late Carboniferous into the Permian. Late Permian coal measures were deposited following uplift of this area# and are now exposed as scattered small outliers and fault blocks. Similar Late Permian coal measures occur in the subsurface Olive River Basin further north on Cape York Peninsula. The New England Orogen was a transitional tectonic regime during the Permian, and was the site of dominantly marine sedimentation, calcalkaline volcanism, and granite emplacement. A major volcanic chain, the Camboon Volcanic Arc, developed along the western margin of the orogen in the Early Permian. It apparently formed the eastern shoreline of the Bowen Basin except in its central section, where the deep marine Grantleigh Trough may have been one of the main connections with the ocean. On the Yarrol Shelf, Early Permian sediments and volcanics overlie Late Carboniferous strata conformably. Elsewhere in the eastern and southern parts of the New England Orogen in Queensland, Permian shallow marine sediments and volcanics were laid down on a basement of folded and partly uplifted Devonian and Carboniferous strata, and are now exposed mainly in small isolated fault blocks. Permian rocks are most extensive in the Gympie area, where they comprise basaltic volcanics overlain by marine clastics with a prominent limestone bed. The western part of the New England Orogen was folded and faulted in Middle to Late Permian time (Hunter-Bowen Orogeny). The emplacement of numerous Late Permian to Middle Triassic granitic plutons and the eruption of extensive post-orogenic Middle Triassic volcanics in the area south of Rockhampton completed the cratonisation of this region.
12.
1.
Convenors:
ENERGY RESOURCES
J.W. Beeston and P.E. Balfe, Geological Survey of Queensland, GPO Box 194, Brisbane, 4001
13. PETROLEUM EXPLORATION - HISTORY AND FUTURE TRENDS Randal,
M.A., Geological Survey GPO Box 194, Brisbane,
of Queensland, 4001
Only 20 per cent of Queensland's Permian basins are exposed at the surface or occur in near-surface situations, and this has greatly influenced the history of exploration. The first major effort was the drilling of holes at Hutton Creek and Arcadia in the Denison Trough by O i l Search Limited in the latter 1930s. Another important Permian test was SQD Morella 1 , also in the Denison Trough. In I960, Queensland's first petroleum discovery (gas/condensate) was made by UKA Cabawin 1 from Late Permian rocks in the Surat/Bowen Basin. This was followed in 1961 by AAO Glentulloch 1 (gas) in the Denison Trough; to date another six discoveries have been made in this part of the Bowen B a s i n . In the Surat/Bowen Basin another three have been m a d e , but there the Permian sequence is a secondary target o n l y . In 1 9 6 0 , the presence of Permo-Triassic rocks in the southwestern part of the State was first recognised by the Delhi/Santos Group who subsequently defined the broad limits of the Cooper Basin. The first successful well in the Queensland part of the Cooper Basin was that group's Roseneath 1 gas well in 1969. Exploration in the Galilee Basin also commenced in 1960, but to date 50 wells have resulted only in minor gas and oil shows. Until 1980, activity in this region was minimal. Future exploration trends will hinge on both technical and economic factors. Improvements in seismic techniques have enabled better definition of structures and the importance of petroleum geochemistry and of stratigraphic and sedimentological processes is clearly evident in current exploration. Funds for continuing exploration will be dependent on a reasonable success ratio, but this can only come from continuing data acquisition.
PERMIAN GEOLOGY OF THE COOPER BASIN Zwigulis, M., Delhi Petroleum GPO Box 2364, Adelaide,
Pty 5001
Abstract has not been received
Ltd,
14. COOPER BASIN PETROLEUM - EXPLORATION AND DEVELOPMENT Armstrong,
J., Santos North
Limited, 183 Melbourne Adelaide, 5006
Street,
The Permian-Early Triassic Cooper Basin underlies Jurassic to Cretaceous age sediments of the Eromanga Basin in northeastern South Australia and southwestern Queensland, Within the Cooper B a s i n , the Permian Gidgealpa Group includes the Tirrawarra Formation, which holds the bulk of the oil reserves and the Toolachee and Patchawarra Formations which hold the bulk of the gas reserves. Since 1954 f over 270 wells have penetrated the Permian-Triassic section, resulting in reserves of 2.94 TCF sales g a s , 253 MM barrels recoverable gas condensate, and about 28 MM barrels recoverable o i l . Permian oil reserves have been supplemented by recent oil discoveries in the Eromanga B a s i n . Currently about 470 MMCFD of sales gas is being supplied to the Adelaide and Sydney markets by pipeline. Development of the Cooper Basin liquids is proceeding with crude oil production scheduled to commence early in 1983. Condensate production will be on stream later in 1983 and LPG production will commence in 1984. The 35.5 cm (14 inch) pipeline designed to carry these liquids to Spencer Gulf in South Australia is currently being laid. The liquids project represents A$l.l billion investment for Cooper Basin partners. In the Queensland section, there are 10 gas discoveries and an additional two oil discoveries within the Eromanga Basin. Early development of these will advance the investment in oil and gas exploration of both the Cooper and Eromanga Basin.
15. RAPID EVALUATION OF ORGANIC MATURATION FROM HEAD SPACE GAS ANALYSIS - APPLICATIONS IN THE DENISON TROUGH AND COOPER BASIN Boreham,
C . J . , Bureau of Mineral Resources, PO Box 378, Canberra, 2601
Analysis of the light hydrocarbons (C^-C4) in the organic and miner i matrix of sedimentary rocks indicates the amount and degree of m 'uraiion of organic matter present. Canned cuttings from recent exploration wells in the Southern Denison Trough of the Bowen Basin and the Queensland part of the Cooper Basin have been analysed for their light hydrocarbon c o n t e n t , and the organic maturation levels derived through this rapid technique reveal that Permian sequences in both basins are mature to over-mature for those sediments that show the greatest source rock potential. Integration of these results with more detailed geochemical studies shows that, for the mainly gas-prone organic matter in the Southern Denison T r o u g h , the oil generation zone comprises much of the Cattle Creek Formation a n d , in p a r t , the Reids Dome Beds. For the Permian Gidgealpa Group and Merrimelia Formation in the Cooper Basin, predominantly gas-prone organic matter underlies the zone of maximum hydrocarbon generation in the southwestern part of the basin, while similar sediments to the northeast envelop the zone. This suggests that, in the northeastern regions, present-day hydrocarbon generation may be taking place within these source rocks, though their thicknesses are much less than those further to the southwest.
THE APPLICATION OF COAL PETROLOGY TO OIL EXPLORATION Beeston,
J . W . , Geological Survey GPO Box 194, Brisbane,
of Queensland, 4001
Coal petrological techniques including white-light incident and autofluorescence emission microscopy have been employed in a study of coal and petroleum-bearing strata in the Permian Denison Trough of the Bowen B a s i n . Qualitative and quantitative data generated on coal and phyteral material have been correlated with data from palaeobotany, palynology and sedimentology, and organic facies models have been p r o d u c e d . Included material considered to have petroleum-generating potential has been distinguished. The chemical and physical properties of both the total organic matter and that with petroleum-generating potential are considered to be the result of four distinguishable factors, namely florogenesis, degradation, sedimentation and thermal m a t u r a t i o n . It has further been shown that variations within these factors reflect differences in the sedimentary environment, and that organic facies assemblages can be correlated with litho-depositional systems. With detailed microscopical assessment it is thus possible to distinguish the type, quality and placement of potential petroleum generating m a t e r i a l , and to determine the distribution of source rocks within the stratigraphic and geographic framework.
16.
2.
Convenor:
ECONOMICS AND ENGINEERING
G.W. Hofmann, Geological Survey of Queensland, GPO Box 194, Brisbane, 4001
17. EVALUATION OF COAL PROPERTIES FOR OPTIMUM ECONOMIC DEVELOPMENT AND UTILIZATION OF THE COALS IN THE RANGAL COAL MEASURES AT CURRAGH NORTH OF BLACKWATER, CENTRAL QUEENSLAND Svenson, D. , & Peterson, Mining Ltd, 370 Queen
M.S., Curragh Queensland Street, Brisbane, 4000
Authority to Prospect 217C held by the State Electricity Commission of Queensland (SECQ) encompasses the uppermost Permian Rangal Coal Measures between the MacKenzie River and Blackwater. Its acquisition by the SECQ has presented a unique opportunity for private enterprise to plan the optimum economic development of the coal resources, by optimization of the steaming coal production for local coal generation and of high quality coking coal production for export. At C u r r a g h , four seams will be mined - A r i e s , C a s t o r , Pollux and O r i o n . Oxidized coal from all seams will be used in raw steaming coal production. A detailed evaluation program has demonstrated that all of these seams have potential for both steaming and coking coal production. To ensure continued demand in a competitive coking coal m a r k e t , only high quality coking coal production is planned, using dense media cyclone and froth flotation processes now well established in the Bowen Basin. The consequent sacrifice in yield of coking coal enhances both the yield and quality of the proposed by-product 'middlings' of steaming c o a l . Typical of the Rangal Coal M e a s u r e s , the reactive maceral constituents of the coal tend to occur in the more finely banded seam sections and these in turn are generally more finely cleated and more brittle than the dull coal sections, which tend to be more massive and harder as generally typical of the inert macerals. Float/sink testing of different size fractions has confirmed such trends in the Pollux Seam throughout the mine area, and locally in the other seams. This size separation, when shown to be effective, will precede dense-media cyclone processing in the production of coking c o a l , with the coarse fractions routed to the steaming coal stockpile together with the 'middlings' of steaming coal processed from the coking coal reject. Raw coal properties show a relatively wide range at Curragh as a result of variation in coal type and frequency of interbanded non-coal. For uniform high-quality coking c o a l production yield will v a r y , and selective mining will be locally necessary for optimum quality and coal-preparation efficiency. Consequently, detailed examination of seam lithotype profiles is essential for efficient production quality evaluation. For effective quality evaluation, pretreatment of core and test pit samples is necessary to simulate plant feed particle size distribution in preparation before float/sink testing. Laboratory froth flotation testing needs to be carefully procedured and interpreted if meaningful yield/ash content relationships are to be obtained. As may be anticipated, coal petrology is proving to be the most effective and important indication of coking coal quality. Problems of relatively low ash fusion temperature and low volatile matter content are indicated for steaming coal production, of otherwise good quality, at C u r r a g h .
18. THE INFLUENCE OF STRUCTURE ON THE DEVELOPMENT OF UNDERGROUND COAL MINES IN THE WESTERN BOWEN BASIN Devey, D.M., Utah Development Co., Peak Downs Mine, Private Bag, Moranbah, 4744 Evaluation of coal deposits in the past has tended to overemphasise the delineation of adequate reserves of saleable coal and the appraisal of likely roof and floor conditions at the expense of an adequate understanding of the geological structure. Exploration and mining experience in the western Bowen Basin has indicated that future evaluations should direct greater initial effort into clarification of structure and assessment of seam gas if the underground reserves are to be economically developed. Four mine areas in the region extending from Goonyella to Blackwater have been evaluated by the Utah Development Company since 1975 with the purpose of developing underground mines. Early in the evaluation, the Rangal Coal Measures were postulated as areas more difficult to mine due to the risk of high seam-gas volumes and the expected high fault frequency. H e n c e , more emphasis was placed on detailed evaluation of the Moranbah Coal Measures in areas extending from Goonyella to Norwich Park. This evaluation led to the development of the Harrow Creek Colliery in 1978 and has indicated that even on the 'gently dipping' Collinsville Shelf the frequency of tectonic structures varies significantly from north to south. Drilling over the last seven years has suggested the existence of extensively faulted zones which would preclude economic underground m i n i n g . The stratigraphy and interpreted structure for three of the areas evaluated since 1975 are discussed. The problems encountered during a clarification of the geological structure in the three areas are outlined.
19. GEOTECHNICAL CONDITIONS AFFECTING STRIP COAL MINING IN THE BOWEN BASIN Davies,
A.L. , Utah Development GPO Box 1389, Brisbane,
Company, 4001
The geology and geomechanical character of the overburden, floor and inter-seam sediments have a very significant influence on the operation of strip coal m i n e s . The influence of these factors will be increased as strip mining progresses to greater depths in the future. This paper summarises the range of geotechnical conditions encountered at the four Central Queensland Coal Associates mines operating in Permian coal measure sediments on the northwestern edge of the Bowen Basin (Goonyella, Peak D o w n s , Saraji and Norwich Park mines). The manner by which these geotechnical conditions influence mine design and operation is reviewed on the basis of experience gained during mining and associated research studies in such areas as highwall slope stability, spoil pile stability, excavation requirements, and seepage and groundwater c o n t r o l .
GEOLOGICAL EVALUATION OF THE THEODORE NORTH COALFIELD Coxhead, B.A., £ Brandt, B.A. , CSR Ltd, Coal Division, 239 George Street, Brisbane, 4000 The Theodore North Coalfield is located near the town of Theodore, 170 km southwest of the central Queensland coal port of Gladstone. It covers a 14 km strike length of Late Permian Baralaba Coal Measures on the southeastern flank of the Bowen Basin. Rights to the deposit and to the adjacent Theodore South Coalfield, which covers a further 33 km strike length of the Baralaba Coal Measures, are held by Theodore Coal Pty Limited on behalf of CSR Limited (60%) and the Shell Company of Australia Limited (40%) under MLA 385 (Mt Morgan) a n d A P 2 0 2 C . 1
Reserves of raw coal 'in situ in the Theodore North Coalfield have been determined from the results of 1 286 drill holes of which 640 were partly or fully cored to provide 849 cored coal seam intersections used for the calculations. The reserves of raw coal are: Measured (to 500 m) Indicated Class I (to 750 m) Total
331 080 000 tonnes 252 800 000 tonnes 583 880 000 tonnes
Studies of the technical and economic feasibility to establish a 4.5 million tonnes per annum open pit mine at Theodore North have been completed. Commitment by Theodore Coal to proceed with development of the mine is expected in the last quarter of 1982.
20.
3.
Convenors:
PALAEONTOLOGY
C.B. Foster, Western Mining Corporation, PO Box 409, Unley, 5061, and L.J. Hutton, Geological Survey of Queensland, GPO Box 194, Brisbane, 4001
21. REVIEW OF THE TIME FRAME FOR THE PERMIAN OF QUEENSLAND Foster,
C.B., Western Mining Corporation PO Box 409, Unley, 5061
Ltd,
Of fundamental importance to all branches of the earth sciences, particularly those employed in exploration of fossil fuels, is the establishment of a time frame against which events in the rock record can be considered. For maximum effectiveness, the framework should be used globally and criteria for recognition widely understood. Current concepts of the upper and lower boundaries of the Permian system are reviewed in this paper, and the palaeontological and radiometric data used to delimit time subdivisions of the Queensland Permian are re-assessed. International chronologic correlations have been achieved using data from geographically scattered localities. These data can be applied to basin studies only when they have been incorporated, through detailed mapping and palaeontological studies, into the local stratigraphic framework.
THE SEQUENCE OF FAUNAS IN THE TIVERTON FORMATION, NORTHERN BOWEN BASIN 1 1 2 Waterhouse, J.B. , Briggs, D. , and Parfrey, S. 2. Department of Geology and Mineralogy, University of Queensland, St Lucia, 4067 2. Geological Survey of Queensland, GPO Box 194, Brisbane, 4001 The sequence of faunas through the Tiverton Formation near Homevale Station is analysed. Several major faunas are recognised. A basal meagre fauna of Tomiopsis is overlain by a thick sequence dominated by genera especially common in eastern Australia: Eurydesma, Echinalosia f Anidanthus, Terrakea, Tomiopsis and other forms. The upper part is dominated by Lissochonetes, with Attenuatella, and rare ammonoids. The overlying faunal assemblage is dominated by species of Wyndhamia and Taeniothaerus. These faunas are traced through the Bowen Basin, and compared with other faunas in eastern Australia and Gondwana.
22. B I O S T R A T I G R A P H I C A P P R A I S A L OF PERMIAN F O R A M I N I F E R A FROM THE D E N I S O N T R O U G H (BOWEN B A S I N )
Palmieri,
VGeological Survey GPO Box 194, Brisbane,
of Queensland, 4001
The biostratigraphic study of Permian non-fusulinid calcareous foraminifera has been restricted by their rarity as isolated individuals and their occurrence in compact rocks. Their study in non-oriented thin sections, as well as in altered rocks, prevented observations of evolutionary and phylogenetic importance. Favourable conditions of sedimentation in Permian basins of Australia promoted the development of a foraminiferal phylogeny which can be traced, though non-continuously, through parts of the Early and Middle Permian marine deposits of the Denison T r o u g h . To understand the phylogenetic evolution of these isolated foraminifera, certain taxonomic changes had to be made: within the suborder Lagenina the grouping of lunucamminid and frondinid forms at family level was necessary, together with the distinction between nodosinellid and nodosariid forms according to recent studies of their test structure. When the taxonomic placement of genera and species was m a d e , evolutionary lineages could be defined and the succession of different faunas achieved meaningful biostratigraphic importance. In the Denison Trough, nine foraminiferal cenozones were defined, and served mainly to correlate Permian marine strata within the Bowen Basin. However, some of the foraminiferal faunas have close affinity with faunas recovered from the Sydney, Perth, Carnarvon and Canning Basins. Besides these possible interregional correlations, a comparison is tentatively indicated with Early Permian (Sakmarian) and Middle Permian (Ufimian-Kazanian) lunucamminid and nodosariid foraminiferal faunas from Russia (Nova Zemlia).
A PERMIAN P A L Y N O S T R A T I G R A P H Y
FOR
QUEENSLAND
Price, P . L . , CSR Oil and Gas Division, GPO Box 880, Brisbane, 4001 The nature of palynomorphs and their ubiquitous distribution in the marine and non-marine Queensland Permian sections with hydrocarbon potential has led to the acceptance of palynology as the dominant biostratigraphic method applied by the petroleum exploration industry. The earliest Permian palynological studies in Queensland were conducted by de Jersey in 1946. In 1962, working on Bowen Basin wells, Evans defined a series of Permian palynostratigraphic units. The initial application of these units in the early and mid-1960's was somewhat 1 fluid, but with additional subsurface data Evans studies culminated in the definition of the Eastern Australian palynological "stages" in 1967. As originally conceived and applied, Evans 1 "stages" were in part based upon assemblage concepts with selected taxa being characteristic of the various units. With closely sampled wells available from the Cooper and Bowen Basin, Paten in 1969 redefined and subdivided Evans 1 stages by nominating the incoming of an index species to define each of the palynostratigraphic boundaries. The general elements of the major zones presently applied to the Permian of Queensland have been described in 1977 by Kemp and others together with the broad biostratigraphic/lithostratigraphic relationships. Refinement and some redefinition of the Permian palynostratigraphic units are required and are in progress.
23. THE PALYNOSTRATIGRAPHY OF THE PERMO-CARBONIFEROUS OF THE GALILEE BASIN, QUEENSLAND Powis, G.D., Esso Australia Ltd, GPO Box 4047, Sydney, 200i Five palynological zones comprise the pre-Triassic sediments of the central Galilee B a s i n . They occur in the Late Carboniferous to Early Permian Joe Joe Group and the Late Permian Bandanna Formation equivalent. Three Late Carboniferous zones occur in the formations below the Aramac C o a l Measures of the Joe Joe G r o u p . The oldest palynomorph assemblages so far recognised in this g r o u p , contain abundant monosaccate pollen as well as a variety of undescribed trilete spores, many of which are characteristic of the European Late Carboniferous. This previously undescribed assemblage is called the Diatomozonotriletes birkheadensis assemblage-zone and is believed to be Westphalian in age. The next-youngest zone is the impoverished Potonieisporites novicus assemblage-zone. This low diversity and transitional assemblage is totally dominated by monosaccate pollen. Between this zone and the Permian zones are the two subdivisions of the Microbaculispora tentula assemblage-zone; a zone which contains palynomorphs characteristic of the Permian zones of Gondwanaland, but is latest Carboniferous in a g e . The change to coal-measure deposition of the Aramac Coal Measures equates to the Permian-Carboniferous boundary. These sediments contain the Early Permian Diatomozonotr iletes towrirowii assemblage-zone. Above the regional unconformity at the top of the Joe Joe Group are the sediments of the Bandanna Formation equivalent, which contain the Late Permian Upper Stage 5c palynomorph zone.
24.
PALYNOSTRATIGRAPHIC COMPARISON BETWEEN THE ARCKARIN6A BASIN, SOUTH AUSTRALIA AND LATE PALAEOZOIC BASINS IN QUEENSLAND Cooper, B.J., South Australian Department of Mines and Energy, PO Box 151, Eastwood, 5063 The Arckaringa Basin is an intracratonic basin in central South Australia comparable with the C o o p e r , Galilee and Bowen Basins in Q u e e n s l a n d . Significant differences result from the lack of volcanics and volcanogenic sediments and from the presence of marine deposits about the Permo/Carboniferous boundary. Deposition is restricted to three overlapping episodes deriving from glaciation followed by marine incursion and then fluvial activity. Palynology was first used by Balme in 1957 to date the Arckaringa Basin succession. Microfloras comparable with Evans 1 Stage 2/3 interval in Queensland are now readily determined. These are especially valuable as a consequence of their excellent preservation and minimal carbonisa t i o n . Thus the area constitutes an excellent biostratigraphic reference for the Late Carboniferous and Early Permian. The microfloral succession in the Lake Phillipson bore is characterised from youngest to oldest by the successive appearance datums of: Granulatisporites trisinus Balme & Hennelly Weylandites lucifer Foster
BASE STAGE 3b
(Bharadwaj and Salujha)
Verrucosisporites naumovae Hart V . pseudoreticulatus Balme and Hennelly
BASE STAGE 3a
G . micronodosa Balme and Hennelly Horriditriletes ramosus (Balme and Hennelly) Bharadwaj and Salujha Microbaculispora tentula Tiwari occurs throughout the section. A significant change in the m i c r o f l o r a , characterised by an incoming abundance of Marsupipollenites triradiatus Balme and Hennelly, was recognised immediately below the naumovae d a t u m .
25. THE ROLE OF THE GLOSSOPTERIS FLORA IN BIOSTRATIGRAPHY A PRELIMINARY ASSESSMENT Rigby,
J.F., Geological Survey of Queensland, GPO Box 194, Brisbane, 4001
Paleobotanical studies are shown to be significant in the correlation and interpretation of bore cores using data gained through the stratigraphic drilling programme of the Geological Survey of Queensland in the Early Permian Reids Dome B e d s , Denison T r o u g h , central Queensland. Correlation between most of the bores considered is of a higher order than with any stratigraphic unit outside the Reids Dome B e d s . S i g n i f i c a n t l y , correlation between the Reids Dome Beds and the Blair Athol C o a l Measures indicates that the latter unit was deposited during the later part of Reids Dome time, although there is no evidence whether deposition of these units ceased simultaneously. Other than Taroom 11/11A below 619 m , and Eddystone 4 below 1 057 m , where leaf fossils predominate, the fossil content of the bores has a large component of stick and woody remains. This implies that plant material was transported before burial as sticks and wood are more resistant to w a t e r , gravity or wind dispersal than leaves.
26.
THE SEQUENCE OF PERMIAN ROCKS AND FAUNAS NEAR EXMOOR HOMESTEAD SOUTH OF COLLINSVILLE, NORTHERN BOWEN BASIN Waterhouse, J.B., & Jell, and Mineralogy, University
J.S., Department of Geology of Queensland, St Lucia, 4067
The rock and macroinvertebrate faunas of the upper Tiverton, Gebbie and Blenheim Formations are described in detail from the vicinity of Exmoor Homestead south of Collinsville, in what has been termed the type area for so-called Fauna III. Stratigraphic columns are provided and it is shown that the formation boundaries by Malone and others (1966) are a r g u a b l e , and difficult to m a p . So-called Fauna III in what has been termed basal Gebbie Formation - we would prefer upper Tiverton Formation - is shown to be closely related to so-called Fauna II of the underlying Tiverton B e d s , and to belong to a Tomiopsis plicaTerrakea dickinsi assemblage found also in the Cattle Creek Shale of the Denison Trough and in the mid-Takitimu Group of New Zealand. The Glendoo Sandstone Member in the middle of the Gebbie Formation with Glendella dickinsi Runnegar, so-called Fauna Illb, remains a fauna difficult to recognise elsewhere, but several species are described from the b e d s , to help with future correlation. The upper Gebbie f a u n a s , classed as Fauna IIIc by earlier workers, are close to those of the overlying basal Blenheim Formation, and critical species are described and illustrated. Two lower Blenheim faunas, the Exmoor and Scottville (Big Strophalosia Zone) of Dear (1972), are shown to be separated by a fauna previously not recognised in the area, characterised by Echinalosia ovalis and Terrakea brachythaera (s.l.). We suggest tentatively that the upper Gebbie and lower Blenheim Formations match the Freitag and Ingelara Formations of the Denison T r o u g h , and Barfield and lower Flat Top Formation of the south Taroom Trough, and the Echinalosia ovalis band may match the Mantuan Productus bed of the upper Peawaddy Formation (Denison Trough) and middle Flat Top Formation (Taroom T r o u g h ) . This implies that correlations in recent years which have placed the Big Strophalosia Bed (Scottville fauna) of the northern Bowen B a s i n , and the clarkei bed north of Clermont below the upper Peawaddy Formation, are incorrect. It would also imply that the correlation between the Maria Formation and Ingelara Shale may not be c o r r e c t . To u s , the clarkei bed north of Clermont is to be correlated with the Pelican Creek fauna of Dear (1972) and the Crocker fauna with the Havilah fauna of Dear near the top of the Blenheim faunal succession. These changes mean that the coal measures developed almost simultaneously across the Bowen B a s i n , rather than in the very staggered and timetransgressive fashion favoured in recent studies. Further work is needed to clarify these correlations, but we suggest that long overdue detailed a n a l y s e s , through detailed sections and m a p s , with publication of systematic descriptions from carefully plotted fossil localities at measured stratigraphic intervals, may help resolve questions of c o r r e l a t i o n . The time for mere fossil lists, and inadequately detailed m a p s , has p a s s e d .
28.
4•
Convenor:
SEDIMENTOLOGY
J . J . Draper, Geological Survey of Queensland, GPO Box 194, Brisbane, 4001
29. SEDIMENTARY ENVIRONMENTS OF THE PEAK DOWNS COAL M I N E , CENTRAL QUEENSLAND Archibald, D., Esso Australia Ltd, GPO Box 4047, Sydney, 2001 Two distinct fluvial regimes contributed clastic sediments to the Upper Permian c o a l measure sequence exposed at Peak Downs. These are lowsinuosity river systems which deposited a suite of sediments dominated by mature quartz arenites, and deltaic distributaries which deposited a suite of sediments with a volcano-lithic arenite fraction. A third suite of sediments, dominated by volcano-lithic arenites, was deposited by a low-sinuosity river system. Clastic sediments occur in discrete lenses (partings) separated from other partings by coal seams. The vertical and spatial sequence of lithologies and sedimentary structures in each parting reflect the progradation and relaxation of the fluvial system that deposited the parting.
30. DEP0SITI0NAL ENVIRONMENTS IN THE RANGAL COAL MEASURES, SOUTHERN BOWEN BASIN Mallett,
C.W., CSIRO Division of Applied Geomechanics, PO Box 54, Mount Waverley, 3149
The Ranga1 C o a l Measures are a widespread formation found throughout the Bowen Basin with a thickness ranging from 100 to 300 m . They terminate coal formation in the Permian. Detailed maps have been prepared of highwall sections exposed in opencut coal m i n e s . Significant characteristics of the formation ares Relatively few seams pre$ent. Seams split and recombine frequently, forming an anastomosing network in cross-section. Interseam sediments can be isolated into discrete units or depositional e v e n t s . Sediments vary rapidly laterally and distinct depositional processes occur in close association. Terrigenous sedimentation occurs in long depositional strips. Bedding dips in coal and surrounding sediments are usually d i s c o r d a n t , with angular differences up to 25°. Interseam sediments indicate that depositional processes associated in time and locality cover typical channels with migrating sand waves, s p l a y s , subaqueous and subaerial levees, and lacustrine deposits. All occur in linear bodies, deposited beside areas of active peat accumulation. The evolution of Permian physiographic features can be recognised in a succession of depositional environments at some localities. The depositional environment is conceived as a very large, long ranging peat swamp with occasional incursions of terrigenous sediment associated with distributary channels. The sedimentary incursions can be singlestoried with the whole interseam interval being generated in one migration of a distributary system. This typically occurs with coarsegrained channel d e p o s i t s , for example at M o u r a , where channel migration rates can be estimated. In other areas, sediment migration is stepwise with up to three positions occupied before an even layer of terrigenous material is deposited over the p e a t . This is common in areas dominated by s p l a y s , where incremental sediment loads are thin and widespread.
31. DEVELOPMENT OF PERMIAN COAL MEASURE LITHOFACIES AT GOONYELLA, QUEENSLAND Johnson, D.P. , Geology Department, James Cook University, Townsville, 4811 A Permian (bituminous) coal measure sequence exposed at Goonyella comprises six lithofacies: sandstone, siltstone/sandstone, siltstone, c l a y s t o n e , clay rhythmite, and c o a l . These are interpreted as fluvial c h a n n e l , proximal splay/levee, distal splay, m a r s h , lake and mire depositional environments, respectively. Detailed mapping using gradational intertonguing relationships and (isochronous) carbonaceous p a r t i n g s , confirms depositional equivalence of these lithofacies. Deposition occurred on a low relief terrain in a cold climate. A belt of sinuous rivers up to 4 km wide formed channel deposits of medium to coarse arkose up to 35 m thick. Crevasses and levees formed wedges (15 m t h i c k , 400 m across) of interbedded siltstone and sandstone, grading downdip into siltstone. Larger composite splay mounds (to 20 m t h i c k , 2-3 km across) were deposited further from the rivers by smaller overflow channels. Distal deposition of sediment occurred in reed swamps and shallow lakes. Peat accumulation was terminated by terrigenous influx in two ways: by a "reed swamp", and by a lake. Using a tuff and a thin coal seam as time markers, it seems that deposition occurred as a series of overlapping, terrigenous lobes gradually filling the m i r e .
CORRELATION BETWEEN THE COMET PLATFORM AND THE DENISON TROUGH, BOWEN BASIN Brakel,
A.T., Bureau of Mineral Resources, PO Box 378, Canberra, 2601
Examination of petroleum and coal bore logs in the Denison Trough and on the Comet Platform shows that the German Creek Formation can be traced southwards as far as the AFO Rolleston bores at a stratigraphic level above the Peawaddy Formation. The Black Alley Shale is then equivalent to the MacMillan Formation and not the Burngrove Formation. This is corroborated by the lithological similarity of the Black Alley and MacMillan formations, the dissimilarity of the Black Alley and Burngrove formations, the presence of the P3c acritarch zone near the base of both the Black Alley and MacMillan formations, the presence of Fauna IV fossils below the German Creek Formation, and the correlation of sandstone members from bore to bore in the Aldebaran - Peawaddy interval.
32.
PRELIMINARY SEISMIC INTERPRETATIONS IN THE TAROOM TROUGH Herbert, C . , Offshore Oil NL, GPO Box 4246, Sydney, 2001 A total of 382 km of seismic lines were shot in ATP 284P, Bowen Basin by Offshore O i l NL during 1980-81. Seismic lines traverse the Mimosa Syncline from Sunlight N o . 1 in the west to Moura N o . 1 in the e a s t . Resolution was generally g o o d . However, loss of resolution across faulted zones and the Expedition Sandstone hinders precise regional correlation. Late Permian sediments attain their maximum thickness of about 4 300 m close to the axis of the Mimosa Syncline. Here/ the Late Permian sequence occurs at a depth from 5 200 m to 9 500 m . The prograding deltaic couplet of the Baralaba Coal Measures/Gyranda Formation in the eastern Taroom Trough correlates with the Bandanna Formation/Black Alley Shale of the Comet Ridge sequence. It is also apparent that the top of the Flat Top Formation in Moura N o . 1 correlates with the top of the Peawaddy Formation in Sunlight N o . 1. The base of the Flat Top Formation may correlate with the basal Peawaddy Formation/Catherine Sandstone part of the sequence. The Barfield Formation thus appears to correlate with the Ingelara Formation but seismic resolution is not sufficient to detail this. The Mimosa Syncline is, in places, severely effected by faults: dominantly high angle thrust or reverse faults, while some appear to be normal faults. It is suspected that the faults may originally have been down-to-the-basin normal faults (end of Early Permian?), which were reactivated by intermittent thrusting from Late Permian to Late Triassic time.
33. THE ORIGIN OF PEBBLES IN MUDSTONES IN THE DENISON TROUGH, SOUTHWEST BOWEN BASIN Draper,
J . J . , Geological Survey GPO Box 194, Brisbane,
of Queensland, 4001
Scattered pebbles have long been noted in marine mudstones in the Denison T r o u g h , Queensland. Recent stratigraphic drilling has enabled a model for their d e r i v a t i o n , transport and deposition to be proposed. Pebbles occur in non-marine as well as marine mudstones in units ranging from the Reids Dome Beds up to the base of the Peawaddy Formation. Mass flow origins are rejected because of the widespread distribution of the p e b b l e s , ubiquitous bioturbation, and absence of facies normally associated with mass flow. Deposition from currents is rejected because of the wide range of grain size, the contrast between slow sedimentation rates and maximum grain size, and the lack of diagnostic sedimentary structures. The model proposed is one of incorporation, transportation and deposition of fluvial sediments in seasonal river ice. Evidence for ice rafting includes the overall slow sedimentation rate, shattered pebbles retaining their original shape, aggregates of pebbles and s a n d , extremely poor sorting, irregular distribution of pebbles, widespread distribution of pebbles and a suitable palaeoclimate. The fluvial origin of the pebbles is indicated by their rounding and sphericity and by the aggregations. Pebbles are restricted to the Denison Trough area and are locally derived.
CARBONATE DIAGENESIS IN COAL MEASURES AT GOONYELLA, QUEENSLAND Johnson, D.P., Geology Department, James Cook University, Townsville, 4811 Extensive early diagenetic carbonate cementation occurs in the Permian Moranbah Coal Measures at Goonyella. Early cementation is evidenced by later compaction around cemented structures. Five distinct styles are recognised s 1. 2. 3. 4. 5.
large cementations; small concretions and stratal cementation; mineralised wood; displacive lenses, and fracture lenses.
Early cementation is associated more with mudstone than sandstone sequences, and the most extensive development occurs in thin-bedded siltstones with minor sandstone beds. The cementing mineral is mainly ferroan dolomite with minor siderite and ankerite.
34.
5.
Convenor:
GEOPHYSICS
0. Dixon, Geological Survey of Queensland, GPO Box 194, Brisbane, 4001
35. S E I S M I C R E F L E C T I O N T E C H N I Q U E S A P P L I E D IN A B O W E N BASIN C O A L F I E L D
Harman,
P.G., The Broken Hill Pty. Co. GPO Box Q6A, Melbourne, 3001
Ltd.,
Between the years of 1978 and 1980, BHP Pty C o . conducted a modern seismic reflection campaign in its Blackwater coalfield. Techniques used were specifically aimed at achieving high quality, high frequency reflection data at depths between 100 and 600 m , where the coal seams o c c u r . The aim of this work was threefold: to locate structures in the immediate vicinity of current mine workings and thereby assist in day-to-day development? to map the areas immediately around the two c o l l i e r i e s , Cook and Leichhardt, to allow future mine planning; and to cover a larger proportion of the mine lease and identify areas suitable for possible future mine development. The method was successful in achieving these aims. In many c a s e s , faults with throws as little as 3 m were detected, and seam splitting could be detected in areas where reasonable geological controls were a v a i l a b l e . Data were of sufficient quality to allow confident mine planning in the area for the first time. The program which covered larger areas of the BHP lease not only assisted in locating areas suitable for future development, but allowed a greater insight into the structure of the coalfield. An understanding of the type of structures observed on the Blackwater seismic sections may assist in further understanding of the structural history of the Bowen B a s i n . O v e r a l l , two major periods of tectonism can be interpreted from the seismic results: normal faulting which commenced during the time of coal sedimentation in the late Permian and continued into the Triassic (Rewan), and thrusting and subsidiary strike slip faulting which occurred during the time of the Dawson tectonism. The latter structures overprinted the normal faulting. Seismic evidence over structures in the Cook colliery area of the lease suggests that a large normal fault has formed a barrier between stress regimes during the period of thrusting, resulting in its remobilisation in a strike slip sense and generating subsidiary tensional block structures in the colliery area. It may be observed that structures in the Blackwater area do not necessarily parallel the main tectonic zone, but have been formed by the response of the local existing structural geology to the superimposed tectonic stress.
36. A R E V I E W OF R E F L E C T I O N S E I S M I C P R O S P E C T I N G IN THE D E N I S O N T R O U G H (BOWEN B A S I N ) D U R I N G 1960 TO 1982
Mollah, R.J., and Mogg, W.G. , AAR GPO Box 880, Brisbane, 4001
Ltd,
Within the Permo-Triassic sediments of the Denison Trough, two generally thick and continuous coal sequences, one close to the top of the Upper Permian and one near the top of the Lower Permian, provide ideal acoustic impedance contrasts for reflection seismic techniques. Consequently, within the state of the art, data quality of recordings have generally been considered to be fair to good over most of the area. The first seismic recordings were made in the early 1960's using singlefold coverage and analog instrumentation, and the original paper records are, in many instances, the only permanent record of the data. These surveys were, however, sufficient to outline the structural attitude of the Denison Trough. With the advent of recording onto magnetic tape, multi-fold common depth point techniques, and computer data processing, beds other than the coal sequences were able to be identified. Modern, high effort seismic methods using digitally recorded and processed data with microchip technology appear to be capable of providing direct detection of hydrocarbons in addition to producing a useful guide to the stratigraphy and the depositional environment. Examples of seismic sections from 1960 to 1982 are discussed together with the latest techniques being employed. Seismic and well data from the Rolleston and the recently discovered Merivale Gas Fields are used in the examples.
SEISMIC DATA ACQUISITION
IN THE G A L I L E E
BASIN
White, T., Esso Australia Ltd, GPO Box 4047, Sydney, 2001 Esso Australia Ltd is conducting a combined regional and detailed seismic reflection survey in the Galilee Basin of central western Queensland. The data acquisition and processing techniques being used, and the related program goals and operational constraints, are described. The vibroseis recording technique was chosen because of the environmental, cost and geophysical benefits it is considered to have. The recording instrumentation incorporates a field computer for initial data processing, which also provides a field capability for evaluating experimental data. Optimum data quality is achieved by the integrated use of modern field and processing techniques. Improved geodetic control is being achieved using satellite surveying methods. The large size of the basin has necessitated the use of mobile, trailer-housed seismic crews. These methods allow the concurrent evaluation of the regional structure of the basin and of likely local hydrocarbon traps.
T I T L E TO BE
ANNOUNCED
Middleton, Delhi Petroleum Pty Ltd, GPO Box 2364, Adelaide, 5001 Abstract was not received
37.
6.
METALLIFEROUS DEPOSITS
Convenor:
D. Evans, Western Mining Corporalion, PO Box 179, Toowong, 4066
38.
A R E V I E W OF M E T A L L I F E R O U S M I N E R A L I S A T I O N A S S O C I A T E D WITH PERMIAN ROCKS IN Q U E E N S L A N D Kay,
J.R., Geological GPO Box 194,
Survey of Queensland, Brisbane, 4001
M e t a l l i f e r o u s m i n e r a l i s a t i o n is a s s o c i a t e d with P e r m i a n rocks in both the H o d g k i n s o n - B r o k e n River O r o g e n of n o r t h e a s t e r n Q u e e n s l a n d and the N e w E n g l a n d O r o g e n on the c e n t r a l - e a s t and s o u t h e a s t e r n m a r g i n s of the State. In the H o d g k i n s o n - B r o k e n River O r o g e n , m i n e r a l i s a t i o n o c c u r s w i t h i n or a d j a c e n t to the m a r g i n s of p o s t - o r o g e n i c p l u t o n i c intrusives of late C a r b o n i f e r o u s to e a r l y P e r m i a n a g e . S i g n i f i c a n t c o n c e n t r a t i o n s of tin d e p o s i t s and m o r e w i d e l y s c a t t e r e d t u n g s t e n , c o p p e r , s i l v e r - l e a d and m o l y b d e n u m d e p o s i t s are f o u n d , m o s t l y in v e i n s and p i p e s . W h e r e c a l c a r e o u s s e d i m e n t s have been i n t r u d e d , there are fluorite-rich s k a r n s , s o m e t i m e s w i t h s i g n i f i c a n t c o p p e r m i n e r a l i s a t i o n . N u m e r o u s small goldb e a r i n g v e i n s are found w h e r e P e r m o - C a r b o n i f e r o u s g r a n i t e s intrude h i g h l y d e f o r m e d B a r r o n River m e t a m o r p h i c s . Late C a r b o n i f e r o u s to early P e r m i a n p o r p h y r y - t y p e c o p p e r - m o l y b d e n u m m i n e r a l i s a t i o n is s u p e r i m p o s e d o n the a r e a . M i n e r a l i s a t i o n in the New England O r o g e n o c c u r s in late C a r b o n i f e r o u s to e a r l y P e r m i a n s e d i m e n t s and v o l c a n i c s as w e l l as late Permian to early T r i a s s i c p o s t - o r o g e n i c p l u t o n i c i n t r u s i v e s . S u b m a r i n e e x h a l a t i v e copperg o l d , s i l v e r - l e a d - z i n c and c o p p e r - m a g n e t i t e d e p o s i t s are found in early P e r m i a n m a r i n e v o l c a n i c s e q u e n c e s , w h i l e d i s s e m i n a t e d g o l d , silver and c o p p e r m i n e r a l i s a t i o n is p r e s e n t in t e r r e s t r i a l v o l c a n i c s of e q u i v a l e n t a g e . S o m e m a n g a n e s e d e p o s i t s m a y a l s o be of v o l c a n o g e n i c o r i g i n . The lower P e r m i a n s e d i m e n t s and v o l c a n i c s c o n t a i n numerous small vein and shear type o c c u r r e n c e s of g o l d , s i l v e r - l e a d - z i n c and c o p p e r . T h e L a t e P e r m i a n to E a r l y T r i a s s i c g r a n i t i c rocks of the New England T a b l e l a n d c o n t a i n tin and tungsten d e p o s i t s , and other intrusives of similar age are c l o s e l y a s s o c i a t e d with v e i n s carrying g o l d , c o p p e r , s i l v e r - l e a d - z i n c , a n t i m o n y , bismuth and m o l y b d e n u m . Skarn d e p o s i t s have z i n c , c o p p e r and m a g n e t i t e . T w o w e l l d e f i n e d belts of PermoT r i a s s i c p o r p h y r y - t y p e c o p p e r - m o l y b d e n u m and gold m i n e r a l i s a t i o n p a r a l l e l the s t r u c t u r a l t r e n d s of the New England O r o g e n .
39.
THE NATURE OF TIN MINERALISING SYSTEMS WITHIN THE HERBERTON-MOUNT GARNET TINFIELD, QUEENSLAND Pollard, P.J., & Taylor, R.G., Geology James Cook University, Townsville,
Department, 4811
Although generally regarded as a single tinfield, the Herberton-Mount Garnet district is better envisaged as a series of individual mineralisation centres which are united by their relationship to specific late phases of Upper Palaeozoic felsic granitoids a n d , more rarely, intrusive porphyries. Whilst there are similarities between centres, they are different in d e t a i l , and these differences are of critical importance in terms of economic potential. T h u s , individual centres can be characterised in terms of detailed geological setting and deposit types, which in turn is reflected in their production history. Greisen-type alteration systems for example, reach a maximum in western and southwestern regions, whilst albitic alteration is best developed in central and western regions. Herberton Hill is noted for a remarkable concentration of chloritic-sericitic quartz pipes in granite, whilst the bulk of production for Emuford derives from chloritic, sulphiderich veins in sediments. The diversity is well illustrated by a study of tonnage-grade diagrams, together with the temporal and spatial relationships between deposit types. This enables an anlysis of the evolution of individual hydrothermal s y s t e m s .
40.
THE DRAKE M I N E R A L FIELD - A UNIQUE ENTITY IN EASTERN A U S T R A L I A Herbert, Advanced
//. , Darling Education,
Downs College of Toowoomba, 4350
T h e D r a k e M i n e r a l F i e l d is a s t r o n g l y m i n e r a l i s e d s e g m e n t of the Drake V o l c a n i c s , w h i c h s t r a d d l e the New S o u t h W a l e s / Q u e e n s l a n d b o r d e r . The v o l c a n i c s , a d e e p l y d i s s e c t e d p i l e of c a l c - a l k a l i n e f l o w s , b r e c c i a s , t u f f s , e p i c l a s t i c b r e c c i a s , laharic d e p o s i t s , v o l c a n o c l a s t i c s e d i m e n t s and s u b v o l c a n i c i n t r u s i v e s , w e r e d e v e l o p e d w i t h i n a broad g r a b e n , f l o o r e d , at l e a s t in p a r t , by c r u s t a l rocks of the Emu Creek B e d s . T h e y a r e s u b - a e r i a l to s h a l l o w m a r i n e , range from b a s a l t i c a n d e s i t e to s o d i c r h y o l i t e and m a i n l y formed during the time interval 260-240 m y b p . T h e v o l c a n i c p i l e has been intruded by s e v e r a l Late T r i a s s i c calca l k a l i n e acid g r a n i t o i d s and n u m e r o u s post Late T r i a s s i c s t o c k s and d y k e s of a l k a l i n e and c a l c - a l k a l i n e d i o r i t e and g a b b r o . T w o m a i n s t y l e s of m i n e r a l i s a t i o n are recognised w i t h i n the v o l c a n i c s : (a)
d i s c o r d a n t v e i n s , g e n e t i c a l l y related to both the Permian volcanic a c t i v i t y and the Late T r i a s s i c p l u t o n i s m ;
(b)
s t r a t a b o u n d d e p o s i t s , g e n e t i c a l l y related to the Permian v o l c a n i c a c t i v i t y and e c o n o m i c a l l y the m o s t important type of ore o c c u r r e n c e in the v o l c a n i c s .
C o m p a r a b l e v o l c a n o g e n i c m i n e r a l i s a t i o n d o e s not appear to have been r e c o r d e d e l s e w h e r e in the P e r m i a n of eastern A u s t r a l i a . H e n c e , the D r a k e M i n e r a l F i e l d m a y w e l l be a unique e n t i t y .
SOME A S P E C T S OF THE CLERMONT G O L D F I E L D I'Ons, M.E., Photogeological Consultant, 256 Margaret Street, Toowoomba, 4350 T h e g o l d p l a c e r d e p o s i t s of Permian age in the C l e r m o n t d i s t r i c t of c e n t r a l Q u e e n s l a n d are unique in A u s t r a l i a . The d e t r i t a l gold in these d e p o s i t s w a s e r o d e d , t r a n s p o r t e d , and c o n c e n t r a t e d by g l a c i a l action and is h o s t e d in t e r r e s t r i a l m o r a i n e s or fluvial d e r i v a t i v e s of these m o r a i n e s w h i c h w e r e d e p o s i t e d at the northern extremity of the Permian ice s h e e t . T h e g o l d in these d e p o s i t s is of high fineness and d o m i n a n t l y c o a r s e ; n u g g e t s in e x c e s s of half an o u n c e in w e i g h t are relatively c o m m o n . M o s t of the other heavy m i n e r a l s occurring with the gold e x h i b i t a high d e g r e e of r o u n d n e s s , indicating a long d i s t a n c e of transport. G l a c i a l a c t i o n is c a p a b l e of eroding c o n s i d e r a b l e v o l u m e s of m a t e r i a l and t r a n s p o r t i n g r e s i s t a n t or m a l l e a b l e heavy m i n e r a l s over long d i s t a n c e s . It is c o n c e i v a b l e that this p r o c e s s played an important p r i m a r y role in the f o r m a t i o n of some of the larger fluvial and m a r i n e p l a c e r d e p o s i t s found in other p a r t s of the w o r l d .
41. A RE-ASSESSMENT OF THE CRACOW 60LDFIELD Hopwood, T., Sedimentary Uranium NL, PO Box 158, North Adelaide, 5006 The Golden Plateau Mine has been the main producer in the Cracow G o l d f i e l d , some 350 km northwest of Brisbane. In 1975, the decision was made to terminate mine operations by Golden Plateau N L , based on what was perceived at the time to be insufficient reserves. This report presents a re-assessment of the potential of the mine and the Cracow G o l d f i e l d . Sedimentary Uranium holds 90 per cent of Assumpsit N o . 1 2 , which was granted A to P 2211M over the area in October 1979. The main lode comprises a complex anastomosing series of steep faultcontrolled quartz-breccia lodes, hosted in a shallow southwesterly dipping volcanic sequence. The host stratigraphy passes upwards from (i) felsic t u f f s , flows and breccias, (ii) andesitic tuffs, fragmentals and flow r o c k s , to an upper sequence of (iii) felsic flows and tuffs. A concept of ore localisation has been developed, leading to criteria for the recognition of potential gold-bearing quartz breccias. Over some two years all data for the mine and the district were c o l l a t e d , re-assessed and summarised. In this recompilation, as much original drill data and raw assay data as possible were used. Some seventeen significant exploration targets have been generated in the district by this program: three in the main mine with opencut potential, eight underground targets in the main m i n e , and six targets in prospects within the d i s t r i c t , all within 3.5 km of the m i n e . The ore potential of the mine lies conservatively in the range of 2.5 million tons of 5 g/t A u , 5 g/t A g , up to 10 million tons of 4 g/t Au and 4 g/t A g . The priority is to determine that target tonnage and grade necessary to establish a viable mining operation. In this there are advantages in that three high priority targets are all accessible by opencut; the metallurgical recovery is proven at better than 93 per cent by the past G.P.N.L. operation. In addition, remnant infrastructure comprising roads, power and water is available from the previous operation. The main shaft is accessible to 6 Level, and the water level in the mine is 8.5 m above 7 Level. In exploration terms it is absolutely essential that the statistics of drill-sampling for gold are fully understood. Because of the dispersed and particulate nature of the gold mineralisation, the score to no-score ratio of drill sampling in productive ore blocks is of the order of 1:7. It is recommended that for deep targets (greater than 100 m) multiply wedged holes should be used to get several intersections through a given interval of lode. It is plainly necessary to develop a mining experience of drilling up potential ore blocks, and bulk testing of these ore blocks in order to develop a practical working relationship between drill sample grades and ultimate production grades. Orientation geophysics indicates that resistivity profiling gives positive results in locating subsurface lode zones or targets beneath Jurassic cover r o c k s , a problem which has plagued some exploration efforts in the p a s t .
42.
THE MOUNT CHALMERS MINE AND ENVIRONMENT, EASTERN QUEENSLAND A KUROKO-STYLE VOLCANOGENIC SULPHIDE ENVIRONMENT Taube,
A & van der //eider, P . , Geopeko, PO Box 5, Mount Morgan, 4714
The Mount Chalmers main and west lodes represent part of a Kuroko-style cluster of mineralized bodies occurring within the Late Permian Berserker B e d s . Several smaller discrete occurrences of mineralization within a 2.5 km radius of the mine show most of the characteristic features of a Kuroko-style orebody but do not have economic grades and tonnages. The mineralized bodies all occur at the same stratigraphic horizon, which is marked by a change in character between the footwall volcanics and hanging wall volcanics, usually at the level of a fine-grained sedimentary unit. The mineralized strata are nearly flat-lying and extend for several kilometres around the m i n e . The footwall volcanics are only exposed at the m i n e . The main structural features are gentle folding, blockfaulting, and localized(?) dewatering cleavage zones related to mineralization. Opencut related zones. aneous)
mining revealed that previously-inferred domal structures are to horst-block faulting in the central parts of the mineralized Gross changes in stratigraphy suggest that early (penecontemporfaults were the original conduits for mineralization.
GOLD-SILVER MINERALISATION WITHIN THE DRAKE VOLCANICS OF NORTHEASTERN NEW SOUTH WALES AND SOUTHEASTERN QUEENSLAND Herbert, //., Darling Advanced Education,
Downs College of Toowoomba, 4350
Gold and silver occur widely distributed throughout the Permian Drake Volcanics as components of vein, stockwork and stratabound base metal sulfide accumulations. Within these, gold occurs as gold and/or in electrum, whilst silver occurs in electrum and a wide variety of sulfosalts, silver sulfides and mixed copper-silver sulfides. All deposits have a strong structural element in their localisation with some being strongly influenced by lithostratigraphic factors. Mineralogical, geochemical and stable isotopic criteria support a volcanic origin for much of the mineralisation.
43.
MINERALOGICAL AND TEXTURAL MODIFICATIONS IN GRANITES ASSOCIATED WITH TIN MINERALISATION, HERBERTON-MOUNT GARNET TINFIELD, QUEENSLAND Pollard, P.J., Milburn, D> , & Taylor, R.G., Geology Department, James Cook University, Townsville, 4811 Recent research within the Herberton-Mount Garnet tinfield has demonstrated the presence of widespread subsolidus alteration within felsic granitoids associated with tin mineralisation. It is suspected that this alteration is ubiquitous. The alteration is expressed by subtle mineralogical-textural changes, which are not related to fractures and which vary in intensity on a regional scale. The most obvious feature is the varying degree of replacement of biotite by c h l o r i t e . The biotites also contain varying amounts of fluorite, c a r b o n a t e , quartz and K-feldspar. The feldspars display considerable evidence of metasomatic readjustment. Replacement perthite ranges from minor to major proportions. Albite occurs as partial rims replacing K-feldspar at plagioclase-alkali feldspar boundaries and as swapped rims on adjacent alkali feldspars. Other textures of uncertain origin include myrmekite, quartz-feldspar intergrowths and quartz-albite microveins. Sericite is widespread as a replacement of biotite, plagioclase cores (associated with fluorite), alkali feldspar and topaz. These and other associated alteration phenomena are well illustrated by the progressive intensity of alteration in granitoids from Herberton, Emuford and Mt M i s e r y .
44.
7.
Convenor:
TECTONICS
C.G. Murray, Geological Survey of Queensland, GPO Box 194, Brisbane,
45 •
POSSIBLE CONNECTIONS BETWEEN THE GYMPIE PROVINCE OF QUEENSLAND AND SIMILAR TERRANES IN NEW ZEALAND Harrington,
H.J., Bureau of Mineral PO Box 378, Canberra, 2601
Resources,
Rocks and structures in the Gympie province are similar to those in the Brook S t r e e t , Maitai and Murihiku terranes in the South Island of New Z e a l a n d . For example, the distinctive Highbury Volcanics at Gympie are very like the Brook Street Formation at Nelson C i t y . The South Curra Limestone is very like the Maitai Limestone in its general a p p e a r a n c e , in its foetid smell When broken, and in its content of pockets of prisms from the Permian bivalve Atomodesma sp. In both countries there have been long and extraordinarily similar debates, independently and in isolation, about whether the rocks are cut by major strike faults. The New Zealand rocks have been traced far out to sea by mapping the Stokes Magnetic Anomaly from aeroplanes and ships. Similar surveys are needed at the Australian end to determine whether the Australian and New Zealand terranes were formerly connected.
46.
A PHOTOSTRUCTURAL CLASSIFICATION FOR PERMIAN COAL BASINS Heidecker, 1. Department University of 2. BP Australia,
1 2 E.J. , & Veitch, S.M. , of Geology and Mineralogy, Queensland, St Lucia, 4067 193 North Quay, Brisbane, 4000
Airphotos provide a powerful geometric basis for geological and engineering classification of fractures affecting coal basins and their covers. Useful geometric characteristics, which are otherwise difficult to capture through mapping (particularly of joints) include: continuity, linearity, spacing, and zonal angular relationships. These characteristics applied to the Galilee Basin of Queensland lead to a photostructural classification into: 1.
Trajectory fractures
These remarkably continuous fractures fit curved trajectories with •braided 1 irregularities. Regular 'bread slice 1 spacing of these fractures is also influenced by bedding properties and structure. 2.
Localised fractures
These are discontinuous and localised along zones. are parallel to or at distinctive angles to zones.
Specific types
This photostructural classification has promising geological and engineering applications as it corresponds with a genetic classification into: 1.
Body fractures
Propogation of these is influenced by body properties and forces and corresponds with cleat in coal. 2.
Imposed fractures
These originate from outside coal-basin infilling and cover rocks through: (a)
dip slip on underlying faults;
(b)
strike slip on primary faults which generate Riedel 1 and 2 and tensional fractures as demonstrated experimentally by Tchalenko (1970).
This classification accommodates observed angular relationships, sigmoidal geometry, senses of shear, and time relationships. Important uses include the prediction of mining conditions, based on fractures revealed by aerial photography.