Publication Name: PESA's Eastern Australasian Basin Symposium II
Authors: A.R. Stacey and R.F. Berry
Date Published: December 2004
Number of Pages: 29
Reference Type: Book Section
Abstract:The Mesoproterozoic basement ofTasmania is overlain by a Neoproterozoic passive margin sequence. Deposition was interrupted by a major Cambrian arc-continent collision. Ordovician to early Devonian, shallow-water sedimentation dominated across the Western Tasmanian Terrane, while a turbidite succession built rapidly across eastern Tasmania. Most sequences were metamorphosed to an overmature state (greater than or equal to 300oC) during a Devonian orogeny.
In the latest Carboniferous, deposition began in the Tasmania Basin. The Late Carboniferous-Permian Lower
Parmeener Supergroup consists of glaciomarine sediments, and is unconformably overlain by Triassic non-marine sandstones and coal measures of the Upper Parmeener Supergroup. A large volume of tholeiitic dolerite intruded the Tasmania basin during the Middle Jurassic. The main body of the Tasmania Basin reached maturity in the Mesozoic and there is evidence for widespread hydrocarbon generation. Locally, evidence for hydrocarbon migration has been detected but no hydrocarbon accumulations have been found.
The Sorell, Bass and Durroon basins were initiated in the latest Jurassic-Early Cretaceous by extension related to
rifting between Australia and Antarctica. By the Late Cretaceous active spreading had begun in the Tasman Sea. The Bass Basin continued to propagate southwards, extending onshore with the opening of the Tamar Graben in the latest Cretaceous, the Devonport-Port Sorell Sub-basin in the Early Paleocene, and the Longford Sub-basin in the Late Paleocene. On the west coast, the Sorell Basin extended onshore with the development of the Macquarie Harbour Graben in the Late Paleocene. During the Late Paleocene-Early Eocene, Tasmania was moving north along a left-lateral transform against Northern Victoria Land. In the Eocene, Australian-Antarctic motion became more divergent along this margin and the most active extension migrated to the southern rift basins. Only the Bass Basin has yielded economic accumulations of gas. Minor hydrocarbon shows have been encountered in the Sorell Basin. The younger southern basins have not accumulated sufficient sediment to reach maturity.