Far Field Alteration in Polymetallic Carbonate Rock-hosted Ore Deposits in Central Peru

Far-field alteration halos to the Antamina, Cerro de Pasco, Colquijirca, Iscaycruz, Milpo, Uchucchacua, Yauricocha polymetallic deposits, central Peril, were examined to identify features characteristic to the escape of spent ore fluids in carbonate rock-hosted systems. Alteration features examined include the metamorphic aureole, proximal and distal veins, metal zonation, and other geochemical dispersion halos. Predictable visible and cryptic alteration patterns extend a minimum of 500 to 800m from sulphide ore bodies. Locally, evidence can be found as much as 1 to 3km from the sulphides. A critical element in using the predictable patterns as exploration vectors is recognizing the permeability structure along which hydrothermal fluids may have exhausted from an ore-forming environment that does not crop out. Visible and cryptic alteration defines high to low temperature zonation features that are continuous between skarn and massive sulphide replacement deposits, strengthening a genetic linkage between these two deposit types.