Depositional History of the Southern Taroom Trough, Queensland

Abstract

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.