The Occurrence, Distribution and Xrd Properties of Hydrothermal Clays at the Golden Cross Epithermal Au-Ag Deposit, New Zealand

Abstract

Hydrothermal clays display distinct zonation around veins in the Empire zone of the Golden Cross epithermal Au-Ag deposit. At shallow levels the main clays are interstratified illite-smectite and tentatively identified chlorite-conensite which grade downwards into illite and chlorite, respectively. Minor at depth corresponds to areas of low permeability. The overall zoning pattern of interstratified and illite presumably reflect a former deposit-scale increase in temperature with depth and towards veins; local variations in clay mineralogy, additionally reflect varying intensities of water-rock interaction. The interpretation of clay mineral transitions must be coupled with other geothermometric data to derive the possible interpretationof the thermal, chemical and hydrologic regimes of fossil geothermal systems.