Abstract: Rifting, Strike-Slipping and Inversion Deformations in the Perth Basin and Implications for Trap Development

SONG, TINGGUANG, Curtin University, TSRC, School of Applied Geology, Perth, Australia

The Perth Basin lies along the western continental margin of Australia and contains up to 15,000 rn of Permian to Cenozoic sediments. It is characterized by a complex sequence of northerly striking sub-basins, troughs and ridges. The present structural complexity of the basin results from the interplay and overprinting effects of rifting, strike-slipping and inversion deformations from Jurassic to Early Cretaceous.

Rifting during the Jurassic generated the majority of the north-striking faults that form the basic framework in the basin. The extension was concentrated on major faults along with subsidiary synthetic and antithetic faults. These faults are generally planar and dip between 45 degrees to 65 degrees, however listric faults also occur at least locally within the basin. The basin underwent dextral strike-slip deformation associated with the Neocomian breakup of the Greater India and Australia. This resulted in a series of NW-trending folds at the restrained bends along major N-S striking faults. Basin inversion is characterized by folding of hanging wall of major faults and basin-wide uplift and erosion. The erosion is most pronounced in the offshore Vlaming sub-basin where up to 3200 m of section may have been removed.

Multiple stages of deformation contributed to trap development. The Jurassic rifting generated some rollover anticlines that may have initiated in Early Jurassic but were probably enhanced by later deformation. However, the majority traps were generated during dextral strike-slip activity and related basin inversion associated with the breakup of Australia and Greater India.

AAPG Search and Discovery Article #90931©1998 AAPG Foundation Grants-in-Aid