The Neogene tectonic history of the North West Shelf, Australia

Abstract

Neogene deformation along the northern margin of the Australian Plate changes character, from a collisional margin to the east in the Timor Sea to a passive margin further west in the Carnarvon Basin. Changes in the deformation style reflect changing regional stress. The continental collision currently underway in the vicinity of Timor Island (the Banda Orogen) influences Neogene deformation in the adjacent Timor Sea, but has little effect in the Carnarvon Basin. The location of deformation also changes, from outboard in the Timor Sea, to inboard in the Carnarvon Basin, with neotectonic events strongly controlled by basement boundaries in the Carnarvon Basin. We propose that Neogene deformation in the Timor Sea and Browse Basin can be explained by an elastic flexure model, whereas in the Carnarvon Basin Neogene deformation is strongly controlled by competency contrasts between basement and basinal rocks. We present a comprehensive model for Neogene deformation across the North West Shelf, based on seismic interpretation and mapping.