Fault Geometry and Deformation History, Northern Carnarvon Basin

Abstract

The Carnarvon Basin has experienced three distinct phases of extension — in the Carboniferous-Permian, in the Upper Triassic to Middle Jurassic and in the Lower Cretaceous. Detailed mapping of fault patterns associated with each event is possible at a regional scale using widespread, publically available 3D seismic data sets.

The complex interaction between NNE and NE-SW oriented Carboniferous and Permian age faults provides the structural framework for subsequent rift events. Both sets of faults show evidence of oblique reactivation under a WNW oriented extensional regime in the Jurassic, somewhat at odds with the general perception of NW oriented extension associated with separation of Argoland from the NW shelf at this time.

Lower Cretaceous extension is much shorter lived, is primarily confined to the SW part of the Northern Carnarvon Basin and is associated with significant uplift and erosion. The relationship of this event to the separation of Greater India from Australia is less clear, but a proposed mantle plume goes some way to addressing some of the observed structural and stratigraphic relationships.