Porphyry-Type Mineralization at Selogiri Area, Wonogiri Regency, Central Java, Indonesia |
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| Authors: | Akira Imai Jumpei Shinomiya Maung Thiha Soe Lucas Donny Setijadji Koichiro Watanabe I Wayan Warmada |
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| Institution: | Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan; , Department of Geological Engineering, Faculty of Engineering, Gadjah Mada University, Yogyakarta, Indonesia; and Department of Geology, Yangon University, Yangon, Myanmar |
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| Abstract: | The Selogiri area, situated in Wonogiri regency, Central Java, is one of several gold prospecting areas in the Southern areas Mountain Range in Java, Indonesia. Three types of dioritic–andesitic intrusive rocks occur in the Selogiri area, namely, hornblende andesite porphyry, hornblende diorite porphyry and hornblende diorite, exposed in a half‐circular depression where volcanic breccia and tuff are widely distributed. The occurrence of stockwork quartz veinlets and associated with magnetite and malachite coating along the cracks in the diorite porphyry suggests porphyry type mineralization. This is also supported by the occurrence of polyphase hypersaline fluid inclusions in the stockwork veinlet quartz. Small‐scale miners are mining NS‐trending quartz veins for gold associated with base metal sulfides. These veins are probably epithermal‐type mineralization that overprinted porphyry‐type mineralization. The Neogene intermediate to silicic hydrous magmatism in Java could have formed the porphyry‐type mineralization in Selogiri, as in the rest of the Sunda–Banda arc. |
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| Keywords: | fluid inclusion Indonesia Java metallogeny porphyry copper deposit stockwork Sunda–Banda arc |
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