17:15 〜 18:45
[HRE13-P11] Intrusion-related Pb-Zn-Cu-(Au) Mineralization in Sassak district, South Sulawesi, Indonesia
キーワード：Epithermal, Sassak base-metal mineralization, Hydrothermal alteration
The Sassak Pb-Zn-Cu-(Au) mineralization is located approximately 1.5 km west of the only well-known porphyry Cu-Au deposit in South Sulawesi Province. The mineralization is hosted by breccia, lapilli tuff, andesite, and dioritic-monzonitic intrusions. Hydrothermal alteration includes quartz-sericite-pyrite-calcite, sericite-chlorite-calcite, and chlorite-epidote-sericite-calcite alteration zones, which are vertically distributed from the upper to deeper part of a studied drill hole (250 m depth). Sulfide dissemination and quartz-sulfide veins, formed in early, main, and late stages were recognized. Based on its cross-cutting relationships, ore texture, and sulfide mineral assemblage, three ore-forming stages are macroscopically and microscopically identified; (i) an early high sulfidation stage characterized by calcite, quartz, pyrite, enargite, chalcopyrite, Ag-bearing tetrahedrite, tennantite, galena assemblages, (ii) main stage mainly dominated by quartz, siderite, pyrite, chalcopyrite, tetrahedrite-tennantite, minor sphalerite, and minor galena, and (iii) late stage characterized by abundant sphalerite, chalcopyrite disease, galena, tetrahedrite, minor enargite, Mo-, Sb-, Cu-bearing sulfide and inclusion of native gold in galena. Sulfide-free carbonate veins as an indication of waning hydrothermal activity were observed. In addition, comb-textured quartz and symmetric banding textures were found. Based on the above-mentioned evidence, base-metal mineralization in the studied area is of typical epithermal deposit.