Continental extension and break-up—using the Australian margins as a case study

The continental margins of Australia provide an excellent natural laboratory for investigations of continental extension and break-up, with examples of failed rifts, multi-phase extensional systems, and volcanic and non-volcanic margins. The thick sedimentary cover across large parts, however, has hindered understanding of the deep crustal and lithospheric structure due to poor imaging. ION Geophysical has acquired deep, long offset seismic data across Australia’s North West Shelf, as well as the Bight Basin on Australia’s southern margin. These programs provide unique imaging of the deep basement structures and the complete overlying sedimentary section, and across all of the terrains from continental crust to oceanic crust. The authors’ interpretation of these data will be discussed in the context of existing models for continental extension and break-up and the resulting implications for the petroleum system: Models of hyper-extension and possible mantle exhumation will be discussed with regards to the Bonaparte, Browse and Bight basins. Multi-phase extension and the development of intra-sedimentary detachment horizons will be reviewed across many areas. Development of volcanic margins, including the effects of dynamic uplift and magmatic intrusions, will be investigated in the Exmouth Plateau. Creation of enough accommodation space to allow the deposition of the observed (~20 km) sedimentary sections in the Carnarvon and Bonaparte basins.