Publication Name: The Sedimentary Basins of WA
Authors: J.D. Gorter & I. Deighton
Publication Volume: 3
Date Published: December 2002
Number of Pages: 42
Reference Type: Book Section
Abstract:
Two and possibly three periods of Phanerozoic igneous activity, involving extrusive and intrusive events, are documented from the offihore northern Perth Basin, Western Australia. A Late Permian-earliest Triassic intrusive event is proved by intersection of igneous rocks in petroleum exploration wells and extrapolated by seismic profiles and aeromagnetic mapping. Radiometric dating, apatite fission track analysis and superposition date the igneous rocks of this event. An Early Cretaceous, probably Hauterivian, event is documented from the outcrop of the Bunbury Basalt in the southern Perth Basin. Deep sea drilling, seismic and aeromagnetic information in the offshore Perth Basin show this igneous province is of greater areal extent, and is associated with the break-up of Gondwana and the drift northward of Greater India during the Cretaceous. Other less well-dated igneous events are interpreted from seismic profiles, magnetic anomalies and drilling intersections. Igneous events can play an important role in the timing and extent of oil generation from petroleum source rocks. Six heat flow scenarios of the Jurassic depocentre in the Houtman Sub-basin were examined to determine likely effects of igneous intrusions on possible basal Triassic and Jurassic source rock intervals.