Complex regional fault history of the Badger Head region, northern Tasmania

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Abstract
Superimposed contraction, extension and oblique‐slip faulting has juxtaposed and segmented blocks and slices of Precambrian metasedimentary rocks, Cambrian marine sedimentary and ultramafic rocks, and Early‐Middle Palaeozoic strata near the boundary between the East and West Tasmania Terranes in the Badger Head region of northern Tasmania. Of greatest significance was post‐Early Devonian southwest‐directed thrusting which caused thin‐skinned style imbrication and led to juxtaposition of the East and West Tasmania Terranes. Polydeformed Precambrian meta‐turbiditic rocks of the Badger Head massif are part of a fault‐bounded allochthonous slice which was brought to the present structural level at this time. An inferred west‐directed Cambrian thrusting event emplaced ultramafic rocks (Andersons Creek ultramafic complex) and produced a tectonic melange (Port Sorell Formation), possibly within an east‐dipping accretionary wedge. The Cambrian event is considered to have involved an imbricated accretionary complex containing dismembered ophiolitic slices. Superimposed Middle Devonian and post‐Jurassic faulting has masked evidence of this event. Post‐Jurassic deformation caused displacement of the Late Carboniferous to Jurassic cover sequence along northwest‐trending strike‐slip and oblique‐slip faults and along the normal faults that produced northwest‐trending rift basins in northern Tasmania. The normal faults are probably related to the extensional event which separated Tasmania from the mainland. The strike‐slip and oblique‐slip faults may be related to the Tertiary contractional deformation that affected southern Victoria.