The Pedirka Basin is a Permian-aged basin that is located in...

The Pedirka Basin is a Permian-aged basin that is located in central Australia, crossing the borders of the Northern Territory and South Australia. It is separate from the Permian sedimentary of the Cooper Basin in the east and Officer Basin Permian sediments to the west. The Pedirka Basin is overlain over most of its extent by the Triassic aged Simpson Basin and younger Eromanga Basin. It is probably one of the more poorly understood basins, both geologically and geophysically.

In terms of resources, petroleum was initially recovered from a Triassic-aged reservoir in Poolawanna-1 about 60 km from the eastern margin of the Pedirka Basin. A residual petroleum column has been interpreted in Colson-1 within the Pedirka Basin, and both hydrocarbon shows and good source potential has been proven in other exploration wells within the Pedirka Basin. The basin also contains extensive coal deposits, especially in the Madigan and Eringa troughs, where the Permo–Carboniferous has been mapped in excess of 1000 m in thickness.

This study proposes that the Pedirka Basin formed as the final stage of a foreland basin, that was formed during and subsequent to the Alice Springs Orogeny (tectonically active between 420 and 200 Ma). The sedimentary fill within the Pedirka Basin appears to have been largely derived from the Alice Springs orogenic highland, which was expressed as a major uplift of basement rocks within 50 km of the preserved western margin of the Pedirka Basin. Organic source rock analyses of the Permian sediments within the basin indicate an unusually high abundance of Type I kerogen, which is suggestive of the presence of freshwater lakes. Evidence for glacial environments (especially moraine deposits) in the basal Permian deposits can be found from seismic reflection data. Both of these lines of evidence, as well as lithological data from exploration wells, support the depositional environment within the Pedirka Basin to be fluvio-lacustrine.

This paper concludes that the Pedirka and Simpson basin sedimentary successions are proximal sedimentary deposits derived from a rapidly eroding eastern expression of the Alice Springs orogenic highlands. Significant local unconformities within the Permo–Triassic in the study area, mapped from seismic data, reflect continued tectonic instability of the region. This tectonic instability has continued to the present day. Petroleum accumulation in the basin appears to have been influenced by the history of tectonic instability.