Normal Fault Growth Analysis of Australia's Southern Margin: Evidence From 3-D Seismic Reflection Data in the Ceduna Sub-Basin, Great Australian Bight and Deep-Water Otway Basin

Abstract

We use three-dimensional (3D) seismic reflection data to analyse the structural evolution of normal fault arrays in the Ceduna Sub-basin and deepwater Otway Basin, along Australia's southern margin. Implementing the use of displacement-distance, displacement-depth and expansion index analysis identifies synkinematic stratal geometries and the timing and style of normal fault growth. The Ceduna Sub-basin displays an array of strike-linked listric faults, decoupled at a marine mud of late Albian age. Differing structural style during the deposition of two independent delta systems of Cenomanian and Campanian-Maastrichtian age has consequently created vertically segmented normal fault growth and structural evolution in accordance with both the segmented coherent fault model and the isolated fault model. This implies that these fault growth models need not be mutually exclusive in their applicability to the structural evolution of a single fault system. Upper Cretaceous basement reactivation at the shelfal hinge zone of the deepwater Otway Basin has nucleated gravitationally driven normal fault segments with growth trends in accordance with the isolated fault model. Fault segments directly above major basement faults display Turonian-Maastrichtian growth and fault segments over basement plateaus only displaying Campanian-Maastrichtian growth. This implies that while the fault growth is driven by gravitational forces in both the Ceduna Sub-basin and deepwater Otway Basin, basement interaction in the deepwater Otway Basin has contributed significantly more control over normal fault growth timing and location.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015