Diatreme Breccias at the Kelian Gold Mine, Kalimantan, Indonesia: Precursors to Epithermal Gold Mineralization

摘要

Early Miocene volcanism associated with a maar-diatreme breccia complex preceded main-stage epithermal gold mineralization at the Kelian gold mine, Kalimantan, Indonesia. Prior to brecciation, andesite intrusions (19.7 ± 0.06 Ma) were emplaced into a package of felsic volcaniclastic rocks and overlying carbonaceous sandstones and mudstones, and a weakly mineralized geothermal system was established. Intrusion of quartz-phyric (19.8 ± 0.1 Ma) and quartz-feldspar-phyric rhyolite (19.5 ± 0.1 Ma) into the active geothermal system triggered widespread fragmentation and formation of the maar-diatreme complex.