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The Permian succession in the southern Taroom Trough is generally believed to be the source of hydrocarbons in the Roma Shelf oil and gas fields and the Moonie oil field. The succession is characterised by complex relationships between marine and fluvio-deltaic facies which reflect marked differences in the depositional history of the Trough.On the basis of transgressive events, the succession has been subdivided into four sedimentary cycles, the boundaries of which do not always correspond to formation boundaries or seismic horizons. Notably, the top coal in any area forms a prominent seismic reflector, but coals in individual areas can be demonstrated to occur at different stratigraphic positions relative to the major interval of coal development. These higher coals reflect changing depositional settings with time.Palaeogeographic reconstructions demonstrate a complex depositional history of sediment input onto a shallow shelf from differing directions and with different rates of input.

No abstract

Liptinite macerals in the Denison Trough are derived from a wide range of organisms including marine acritarchs, and non-marine algae, lycopods, articulates, ferns and gymnosperms. They are formed from the lipid and wax-rich components of these organisms, in particular from specialised tissues, leaves and reproductive organs developed for protection and/or energy storage. They occur chiefly in terrestrially deposited sediments and coals, yet their distribution is variable amongst the seven coal facies assemblages and six disseminated organic matter (DOM) suites distinguished in the trough. The most abundant liptinites are derived from miospores, leaf cuticles and algae. Miosporinite averages 2.6 per cent of total rock and is most abundant in coal seams, banded coals and carbonaceous mudstones that were deposited in ponds, abandoned channels and intraswamp lakes, where it ranges up to 14 per cent. Cutinite averages 0.7 per cent of total rock, and is most abundant in coal seams and banded coals that were deposited as leaf banks in shallow water marginal to peat swamps, where it ranges up to 10 per cent. Alginite averages 0.1 per cent of total rock, and is most abundant in mudstones that were deposited in lake margin ponds, where it ranges up to 22 per cent. Preservation of liptinites (as determined by fluorescence) is best where they were deposited in a quiet regime, at or near their sites of origin, in concentration. In some of these situations they occur in association or juxtaposition with the highly fluorescing, non-structured macerals sporogenite, phylloresinite and fluorinite. The latter are suggested as remnants of material that has otherwise yielded oil.