Arc-continent collision and orogenesis in western Tasmanides: Insights from reactivated basement structures and formation of an ocean-continent transform boundary off western Tasmania
Date
2011
Authors
Gibson, George M
Morse, M.P.
Nayak, G.K.
Ireland, Trevor
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Elsevier
Abstract
Crustal 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.
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Keywords: Arc-continent collision; Basement terranes; Delamerian-Ross orogen; Detrital zircon ages; Ocean-continent transform boundary; Structural inheritance
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Gondwana Research
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Journal article
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2037-12-31
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