Gibson, George MMorse, M.P.Nayak, G.K.Ireland, Trevor2015-12-101342-937Xhttp://hdl.handle.net/1885/64981Crustal architecture in formerly contiguous basement terranes in SE Australia, Tasmania and northern Victoria Land is a legacy of late Neoproterozoic-Cambrian subduction-related processes, culminating in formation of the Delamerian-Ross orogen. Structures of Delamerian-Ross age were subsequently reactivated during late Mesozoic-Cenozoic Gondwana breakup, strongly influencing the geometry of continental rifting and providing clues about the origins and configuration of the pre-existing basement structures. An ocean-continent transform boundary developed off western Tasmania follows the trace of an older Paleozoic strike-slip structure (Avoca-Sorell fault system) optimally oriented for reactivation during the final separation of Australia from Antarctica. This boundary cuts across rocks preserving an earlier record of arc-continent collision during the course of which continental crust was subducted to mantle depths and Cambrian mafic-ultramafic island arc rocks were thrust westwards over late Neoproterozoic-Cambrian passive margin sequences. Collision was accompanied by development of a foreland basin into which 520-600. Ma arc-derived detrital zircons were shed. Following a reversal in subduction polarity, and change to transcurrent motion along the Gondwana margin, Tasmania migrated northward along the proto-Avoca fault system before entering a subduction zone located along the Heathcote-Governor fault system, precipitating a second collision, south-vergent thrusting, and tectonic reworking of the already accreted Cambrian arc-forearc assemblages and underlying passive margin sequences.Keywords: Arc-continent collision; Basement terranes; Delamerian-Ross orogen; Detrital zircon ages; Ocean-continent transform boundary; Structural inheritance201110.1016/j.gr.2010.11.0202016-02-24