Publication Name: The Sedimentary Basins of WA
Authors: Heike I.M. Struckmeyer, Jane E. Blevin, Jacques Sayers, Jennifer M. Totterdell, Ken Baxter and Donna L. Cathro
Publication Volume: 2
Date Published: December 1998
Number of Pages: 34
Reference Type: Book Section
Abstract:
In 1996 and 1997, the Australian Geological Survey Organisation (AGSO) conducted an integrated analysis of the Browse Basin, North West Shelf, based on the structural and sequence stratigraphic interpretation of AGSO's regional deep-seismic and high-resolution seismic grids, modelling of newly acquired refraction data, and flexural isostatic modelling. The model of basin evolution developed during this study has implications for the interpretation of other sedimentary basins on the North West Shelf. The Browse Basin developed in the Carboniferous to Early Permian as a response to north-northwest extension which led to breakup in the Early Permian.The extension was accommodated along northeaststriking large-scale normal faults, but lower crustal/upper mantle extension also occurred. The upper crustal faulting resulted in a characteristic half-graben morphology and a compartmentalisation of the basin into its distinct depocentres, the Caswell and Barcoo sub-basins. Structures resulting from the late Palaeozoic extensional event controlled the location of later structures, as well as the distribution and nature of the sedimentary fill, and influenced the partitioning of pre-Cretaceous petroleum systems within the basin.
Contractional reactivation of Palaeozoic faultsoccurred in the Late Triassic to Early Jurassic, resulting in partial inversion of the half-graben, the formation of large-scale anticlinal and synclinal features within their hanging walls, and differential uplift and erosion of the anticlines. Extension in the Early Jurassic was accommodated by numerous smaller scale faults, which caused the collapse of many of the Triassic anticlines. As with the Palaeozoic extension, the Jurassic extension occurred as upper crustal simple shear as well as significant lower
crustal/upper mantle pure shear during breakup in the Middle Jurassic. The Upper Triassic to Jurassic
structuring events were critical to hydrocarbon trap development and may have caused significant fluid mobilisation in the basin.
Widespread erosion and peneplanation of the basin topography occurred in the Callovian, associated with continental breakup and the initiation of seafloor spreading in the Argo Abyssal Plain. In the Late Jurassic to Cainozoic, accommodation space was controlled by the interplay of thermal subsidence, minor reactivation events and eustasy. Tertiary collision of the Australian and Eurasian Plates produced inversion structures during the Middle to Late Miocene along Palaeozoic fault trends in the Barcoo Sub-basin, and extensive normal faulting in the northern Caswell Sub-basin.