Petrographic Composition and Sulphur Content of Coals Associated with Alluvial Fans in the Permian Sydney and Gunnedah Basins, Eastern Australia
- R. A. Rahmani and
- R. M. Flores
Published Online: 28 APR 2009
Copyright © 1984 The International Association of Sedimentologists
Sedimentology of Coal and Coal-Bearing Sequences
How to Cite
Hunt, J. W. and Hobday, D. K. (1985) Petrographic Composition and Sulphur Content of Coals Associated with Alluvial Fans in the Permian Sydney and Gunnedah Basins, Eastern Australia, in Sedimentology of Coal and Coal-Bearing Sequences (eds R. A. Rahmani and R. M. Flores), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303797.ch3
- Published Online: 28 APR 2009
- Published Print: 26 MAR 1985
Print ISBN: 9780632012862
Online ISBN: 9781444303797
- petrographic composition and sulphur content of coals - Permian Sydney and Gunnedah Basins;
- Permian - containing marine and terrestrial sediments;
- coals, associating with alluvial fan sedimentation - Anthracite Basin;
- Permo-Triassic sedimentation, occurring in eastern Australia;
- Lower Permian Maules Creek Formation-Gunnedah Basin;
- petrography and geochemistry of coal seams
The Sydney and Gunnedah Basins, which formed during the Permian on the eastern margin of Australia, contain restricted marine and terrestrial sediments deposited during two transgressive-regressive cycles. The progradational and aggradational regressive successions include back-barrier, prodelta, lower delta plain, upper delta plain and braided fluvial facies of alluvial-fan systems, the proportion of coarse clastics increasing eastward toward the orogenic hinterland.
Coals associated with a 1000 m thick sequence of alluvial-fan dominated sediments deposited during the Early Permian in the Gunnedah Basin are generally vitrinite-rich (75% mmf), with mainly structured inertinite (semifusinite) and low sulphur contents (<0.55% daf). The coals were formed from a ‘woody’ peat facies under consistently high water-table conditions, with access to terrestrial sulphate only.
Coals associated with alluvial fans and associated fluvial and deltaic systems deposited during the Late Permian in the Sydney Basin consist of high vitrinite (65% mmf), low to medium sulphur (<1.0% daf) seams in the distal facies, and low to high vitrinite (35–65% mmf), low sulphur (<0.55% daf) seams in the more proximal facies. Semifusinite is the dominant intertinite in both facies, and the seams were formed from a ‘woody’ peat. The progressively lower water-table levels and decreasing vitrinite content up the sequence are probably the result of eustatic control and increasing topographic elevation above the water-table.
In coals associated with the upper delta plain and fluvial facies, sulphur is mainly organically bound (70–100%), and the proportion of pyritic sulphur increases to >50% in the lower delta plain facies.