Structural Architecture of Australia's Southwest Continental Margin and Implications for Early Cretaceous Basin Evolution

The southwest margin of Australia is a complex and relatively poorly studied offshore continental region that includes the Perth and Mentelle basins. Plate reconstruction models, in conjunction with regional seismic and potential field data, demonstrate that the margin comprises three major segments: the normal to oblique Mentelle and southern Perth margins and the Wallaby-Zenith Transform Margin. Margin architecture and overlying basin geometries change markedly across segment boundaries and the patterns of structural reactivation during basin development indicate a strong basement control on margin evolution. Linking plate reconstructions and seismic studies provides new insights into Early Cretaceous basin evolution, including the relative timing of breakup within each sub-basin, the timing of accommodation generation and the distribution of breakup related igneous activity. Active development of the Wallaby- Zenith Transform Margin lasted from the Valanginian to the Aptian and controlled structural activity and the patterns of sediment fill across the northern Perth Basin. Immediately prior to Early Cretaceous breakup, the majority of accommodation-space generation and igneous activity was focused within the Zeewyck and Western Mentelle subbasins.