Palaeozoic Geology and Resources of Victoria D.H
AGSO Journal of Australian Geology & Geophysics, 17(3), \07-122 © Commonwealth of Australia 1998 Palaeozoic geology and resources of Victoria D.H. Moorel, A.H.M. VandenBerg l, C.E. Willmanl & A.P.M. Magare Victoria provides the only well-exposed section across the southern cycles of rifting in transtensional rift-like grabens into which volumi part of the Lachlan Fold Belt and the easternmost Delamerides. Al nous silicic volcanics and marine sediments were deposited. The first, though the plate tectonic setting of this region in the Palaeozoic is still Silurian, cycle formed the Cowombat Rift, host to significant base uncertain, the exposure provides important insights into its deposi metal deposits. Away from this rift, there seems to have been a shallow tional, magmatic and structural evolution from the Cambrian to the sea during most of the Silurian in eastern Victoria, into which a very end of the Devonian. condensed limestone seems to have been deposited; however, the lime The oldest known rocks are Late Proterozoic or Cambrian and stone is mainly known from olistoliths in the rift sequence. A second either calc-alkaline arc-type volcanics (mainly in the west) or MORB cycle of transtension in the Early Devonian formed the Buchan Rift types (mainly in central Victoria). The MORB-types host small cop and smaller basins, into which volcanics and/or marine sediments were per- gold deposits and may be the source for the turbidite-hosted gold. deposited. In western Victoria, numerous I-type granites were intruded. The arc-type volcanics have potential for major VHMS deposits. In eastern Victoria, mixed 1-, S- and A-type granites were intruded; The volcanics are overlain by an extensive turbidite sheet, which several broke through to the surface and formed calderas.
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