Seismic Stratigraphy and Subsidence Analysis in the Barrow-Dampier Subbasin, Northwest Australia

Abstract

The objective of this study is to analyze the basin-fill history of the Barrow-Dampier Subbasin (Northwest Shelf, Australia) as a spectacular and complex example of the stratigraphic record of continental breakup. From the Permian until the Holocene, the Barrow-Dampier Subbasin underwent development from a continental sedimentary basin located on the Gondwana continent to a rift graben. When extensional movement ceased, the subbasin developed as a passive continental margin. This study, based on marine seismic data (about 600 km) and logs of 20 wells, includes a seismic stratigraphic analysis tied to wells in the vicinity, chronostratigraphic charts, and the calculation of subsidence curves. The basin fill is characterized by a hierarchically organized architecture. The largest scale are four tectonic-stratigraphic units: prerift (Upper Permian to Pliensbachian), rift (until Callovian), postrift (until the Upper Cretaceous), and convergence (Neogene). The tectonostratigraphic units were built by 13 sequences of the time scale of second-order sequences. Several of the sequences coincide with discrete subsidence episodes on geohistory plots. For most sequences and sequence boundaries, either a eustatic or a tectonically enhanced origin could be established. A series of seismic facies maps for these sequences visualize the sedimentary basin evolution. Several of the second-order sequences can be subdivided into systems tracts or higher order sequences.