Exhaustive gold mineralizing processes of the Sanshandao gold deposit, Jiaodong Peninsula, eastern China: Displayed by hydrothermal alteration modeling

摘要

Sanshandao deposit, located in the western end of the Jiaodong Peninsula, is a typical altered-rock type gold deposit. The hydrothermal alteration in the deposit commences from potassic alteration with mineral assemblage mainly composed of K-feldspar and quartz, with minor sericite. The potassic alteration is followed by silicification that is always weakly developed in this district with minor sericite and gold-absent pyrite. As sericite content increases, the silicification alteration is gradually giving its way to sericitization. Fine sulfide crystals occur in this zone scattering in sericite and quartz matrix, which turns to be sulfidation as hydrothermal alteration proceeding. Gold mineralization is mainly associated with the sulfidation, predominantly hosted by pyrite. The latest hydrothermal alteration and veins consist of quartz-calcite-siderite(-ankerite) crosscutting the former alteration zones. Some auriferous sulfide-quartz veins fill the fractures in the alteration zones, but its gold reserve is limited.