Thrusts and thrust-associated mineralization in the Lachlan orogen

The Lachlan orogen is characterized bya thin-skinned deformational style, with major thrusts and strike-slip faults soling into detachments in the upper and middle crust. Thrusts are divided into three types: type 1 thrusts that formed in apparently unconstrained sediment packages such as Early Ordovician turbidites; type 2 thrusts formed during inversion of mid-Silurian to mid-Devonian constrained sedimentary ± volcanic basins; and type 3 major thrusts that bound the edges of rare upthrusted middle crustal complexes. All three types of thrusts are associated with mineral deposits. Mineralized type 1 thrusts occur in the gold fields of central Victoria. Mineralized type 2 thrusts occur both in the edges of deformed sedimentary and sedimentary ± volcanic basins, as well as within deformed sedimentary and sedimentary ± volcanic basins. Base metal deposits in synrift rocks at Benambra, on the edge of the deformed sedimentary ± volcanic Cowombat rift, are the best examples of mineralization associated with a type 3 thrust. The spatial and geometrical associations between deposits and thrusts in these and other examples lead to the recognition of a class of thrust-associated mineral deposits which constitute a major resource within Lachlan orogen. -from Author