Evolution of Hydrothermal System at the Dizon Porphyry Cu-Au Deposit, Zambales, Philippines

摘要: Abstract. Evolution of hydrothermal system from initial porphyry Cu mineralization to overlapping epithermal at the Dizon Cu-Au deposit in western central Luzon, Zambales, Philippines, is documented terms mineral paragen-esis, fluid inclusion petrography and microthermometry, sulfur isotope systematics. The paragenetic stages throughout are summarized as follows; 1) stockwork amethystic quartz veinlets associated with chalcopyrite, bornite, magnetite Au enveloped by chlorite alteration overprinting biotite alteration, 2) chalcopyrite pyrite stringers sericite 3) stringer molybdenite 4) WNW-trending veins sphalerite galena deeper part, while enargite stibnite shallower levels advanced argillic alteration. Chalcopyrite bornite veinlet (stage have precipitated initially intermediate solid solution (iss) (bnss), respectively. Fluid inclusions consist gas-rich polyphase inclusions. Halite dissolves temperatures ranging 360dC >500dC but liquid (brine) gas (vapor) do not homogenize <500dC. The maximum pressure minimum temperature during deposition iss bnss estimated be 460 bars 500dC. Fluid mainly In addition possible presence saturated NaCl crystals time entrapment that exhibit liquid-vapor homogenization lower than halite dissolution some samples, wide range 230dC 270dC >500dC, respectively, suggests heterogeneous gaseous vapor hypersaline brine. about 25 245dC. Fluid dominated accompanied minor liquid-rich between 350dC 490dC. Fluid vuggy subordinate below 500dC. composed two-phase inclusions, they into phase widely 190dC 300dC (suggesting boiling) salinity ranges 1.0 wt% 3.4 equivalent. A 15 for dilute aqueous which precipitated. In a change temperature-pressure regime lithostatic hydrostatic fracture-controlled sphalerite, decrease supposed occurred due unroofing or removal overlying piles evolution system. The majority isotopic composition sulfides ±0 % +5 %. Sulfur originated an iso-topically uniform homogeneous source, single system.