Officer Basin

The large intracratonic Neoproterozoic to Late Devonian Officer Basin of Western Australia and South Australia covers about 410,000 km² and has a maximum sediment thickness of 10,000 metres. There are several major depocentres, including the Birksgate Sub-basin, Munyarai Trough, Wintinna Trough, Manya Trough and Tallaringa Trough in South Australia and the Gibson Sub-basin, Yowalgo Sub-basin, Lennis Sub-basin, Waigen Sub-basin, Wells Sub-basin and Blake Sub-basin in Western Australia.

Following a period of minor, short-lived rifting, thermal sag allowed deposition of predominantly fluvial and marine siliciclastic and carbonate sediments and evaporites. This succession is terminated by an erosional surface which is overlain by fluvial and glacigene sediments associated with the Sturtian and/or Marinoan glaciations. Depositional patterns were changed abruptly by the Petermann Ranges Orogeny with extensive uplift along the northern margin of the basin feeding deposition of widespread fluvial and marine siliciclastics with carbonates during the latest Proterozoic-Late Cambrian. Cambrian sedimentation ceased with the onset of the Delamerian Orogeny, which was accompanied by extensive basaltic volcanism in the central and western parts of the basin. A period of extension during the Ordovician led to deposition of shallow marine to fluvio-deltaic siliciclastics in the northeastern part of the basin. Uplift associated with the Alice Springs Orogeny terminated sedimentation in the latest Ordovician or Silurian. A suspected extensional event during the Late Devonian provided accommodation space for the deposition of fluvial siliciclastics also in the northeastern part of the basin.

The basin is poorly explored, with only about 15,000 line-km of 2D seismic coverage and only about 20+ exploration wells have been drilled. Numerous hydrocarbon shows from four distinct oil families are recorded from Neoproterozoic and Cambrian sediments, but there have been no commercial discoveries. Possible traps range from simple anticlinal closures, diapirs and fault-induced rollovers as well as stratigraphic traps.