Biomarker distributions and stable isotopes (C, H) establish the age and palaeoenvironmental conditions spanning the Permian/Triassic in the northern onshore Perth Basin

Abstract

The Perth Basin is located in southwest Western Australia (WA). It is a deep, north to south trending basin, extending over 1,000 km from Geraldton to the north of WA (how far north is this?). The Perth Basin sediments comprise of rocks of Permian-Early Cretaceous in age. The Perth Basin petroleum system has been intermittently explored for the last few decades, resulting in the production of gas and oil from several onshore fields (e.g. Summons et al, 1995). The perception that the area is gas prone has been challenged with the recent discovery of the near-shore Cliff Head oil field. The premier effective source rock for petroleum in the Perth Basin is the marine Kockatea Shale, with the hydrogen-richest interval being the Sapropelic Unit of the Hovea Member (use either a Thomas or Barber reference here). As well as being central to the petroleum prospectivity of the Perth Basin, particularly the lateral extent offshore of the Kockatea Shale, deposition of the Kockatea Shale was intimately associated with events spanning the Permo-Triassic mass extinction. Therefore, this study continues our focused research into better defining the age, organic facies and deposition conditions associated with this World class source rock and their link with the global system over this confined time interval.