Geochemistry in prospectivity modelling: investigating gold mineralization in the Taupo Volcanic Zone, New Zealand

Prospectivity modelling of epithermal gold mineralization has been completed over the Taupo Volcanic Zone (TVZ), North Island, New Zealand. The TVZ is unique in that it is a present-day analogue of the environment in which many epithermal ore deposits, such as in the adjacent Hauraki Goldfield in the Coromandel Volcanic Zone, are formed. The model utilizes compiled digital data including: historical exploration data; geological data from the Institute of Geological and Nuclear Sciences Quarter Million Mapping Programme over Rotorua, Hawkes Bay and Taranaki; recent Glass Earth Gold Ltd geophysical data; and historic exploration geochemical data from rock-chip and stream sediment samples. The weights of evidence modelling technique was used to determine spatial correlations between known gold prospects and predictive maps, created from the available data, representing each component of the currently accepted mineral system model for epithermal gold. Despite the limited coverage of several data-sets, the resulting prospectivity model over the TVZ confirms potential for gold mineralization. The most prospective areas are those associated with active and inactive hydrothermal systems represented by areas of hydrothermal alteration. The Rotokawa and Waiotapu hydrothermal centres have been identified as particularly prospective, suggesting these systems may represent modern analogues of epithermal gold mineralization.