Abstract

Reconstructions of southern Gondwana place Tasmania at the triple junction of Paleozoic Australia, Antarctica, and New Zealand. Tasmania, however, differs in pre-Jurassic stratigraphy and structural style from the southeastern Australian mainland and northeast Victoria Land, Antarctica. Most notably, (1) Precambrian basement is exposed in Tasmania but not in the Lachlan fold belt of the Australian mainland. Precambrian basement in northeast Victoria Land and the Adelaide-Kanmantoo fold belt of southeast Australia differ in stratigraphy and metamorphic history from that in Tasmania; and (2) western Tasmania is dominated by west-verging Cambrian and Devonian thrusts, whereas the Lachlan fold belt is dominated by east-verging Devonian thrusts, the Adelaide-Kanmantoo fold belt is dominated by westverging Ordovician thrusts, and northeast Victoria Land is dominated by east-verging Ordovician thrusts. An explanation for the misfit between Tasmania and the other regions is that ancestral Tasmania (1) was positioned east of mainland Australia with possible Precambrian links to North America (SWEAT hypothesis), and (2) was progressively emplaced by a combination of west-directed Cambrian and Devonian thrusting, Cretaceous crustal stretching to form the Gippsland and Bass basins, and finally Tertiary wrenching south of the Gambier-Gabo line.

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