Regional paleodepositional environment of the Cretaceous in the Great Australian Bight – a support for frontier exploration

Abstract

To reveal the development of the depositional environment in the Great Australian Bight, regional and high-resolution 3D-seismic interpretation and palynological evidence from well data was integrated with tectonic plate- and paleo topographical-reconstructions. Results from that work explain the drainage patterns and changes in the sedimentary evolution. A maximum transgression at the Cenomanian–Turonian boundary causes the deposition of the expected main source rock interval at the base of the Tiger mega-sequence. This is supported by Integrated Ocean Drilling Program wells (2017), asphalite strandings and dredge samples from the basin. A relative sea-level drop in the mid-Turonian initiates a forced regression and sand deposition in more distal parts of the basin. As a third mega-sequence the Hammerhead Formation progrades into the basin, depositing several thousand metres of deltaic sandstones and lagoonal shales. Our source to sink model based on our gross depositional environment maps could explain the presence of source rocks and reservoir intervals within this frontier exploration basin.