A fresh look at the late Palaeozoic tectonic history of Western-central Australia

This paper investigates a simple model for the evolution of the central Australian (Amadeus, Officer and Ngalia) basins and the adjacent Canning and Bonaparte Gulf basins at the time of the Alice Springs orogeny. Supported by evidence from surface geology, stratigraphic correlations, structural geology, recent deep seismic and gravity anomaly data, the proposed model suggests a genetic link between the two groups of basins. The model calls for a crustal scale shear zone, which has been named by the authors, the Lasseter Shear Zone, running through the Halls Creek Province and continuing south between the Canning and Amadeus basins and beneath the Western Officer Basin. This shear zone would have been active during the Middle Devonian to early Carboniferous, separating crustal blocks in compression to the east from crustal blocks in extension to the west. Several driving mechanisms acting along the margins of the Australian plate can be called upon to account for the contrasting, yet contemporary, types of deformation on either side of the shear zone.