PB ISOTOPE FINGERPRINTING OF MESOTHERMAL GOLD DEPOSITS FROM CENTRAL VICTORIA, AUSTRALIA - IMPLICATIONS FOR ORE GENESIS

New Pb isotope data from three major mesothermal lode gold deposits (B allarat West, Tarnagulla, Maldon) in central Victoria support a model whereby the metals derived from a large reservoir with a long residenc e time in the crust below the Palaeozoic Lachlan Fold Belt. The Pb iso topic ratios of least radiogenic samples from these deposits are in cl ose agreement with published Pb signatures for turbidite-hosted gold d eposits, and for Devonian granites, elsewhere in the Lachlan Fold Belt . Despite their spatial distribution and variations in the geological setting, the Pb signatures point to the extraction and transport of me tals from a crustal source area by long-lasting, large-scale hydrother mal systems, resulting in the prominent homogenisation of Pb isotopic ratios. The enduring interaction between large hydrothermal systems an d an extensive crustal source reservoir were a vital prerequisite in t he formation of the Victorian gold province. In this regard, the prosp ectivity of Victoria is analogous to world-class ore provinces elsewhe re, such as the Archaean Yilgarn Block in Western Australia.