ORE MINERALOGY AND HOST ROCK GEOCHEMISTRY OF THE POLYMETALLIC EPITHERMAL DEPOSIT AT SORIPESA PROSPECT AREA, EAST SUMBAWA, INDONESIA

SAN OO, Dr. Ir. Wayan Warmada

2012 | Tesis | S2 Teknik Geologi

quartz diarahkan Mineralisasi dari daerah prospek Sorepisa terletak di bagian timur Pulau Sumbawa, Indonesia. Mineralisasi dari daerah penelitian terutama struktural mengontrol dan tren vena semua di daerah penelitian terutama NW-SE dan NE-SW arah. Mineralisasi dari daerah penelitian dilakukan dengan sayatan tipis studi petrografi, mineralogi bijih studi mikroskopis, X-ray metode fluoresensi untuk geokimia dan difraksi dengan sinar-X analisis mineral lempung berorientasi untuk mineralogi perubahan terkait dengan mineralisasi di daerah penelitian. Karakteristik geokimia dari batuan induk di daerah penelitian adalah Na2O+K2O vs SiO2 diagram dan Ti / Zr vs Nb / Y diagram menunjukkan basalt, basaltik andesit, andesit ke dasit seri dan basalt / andesit dan andesit lapangan. Di sisi lain, diagram Cr-Y batuan host vena pada daerah penelitian termasuk dalam bidang basal busur vulkanik dan dalam bidang basal plate. Mineral bijih komposisi daerah penelitian adalah emas, perak, galena, pirit, kalkopirit, sfalerit, kalkosit, gutit, perunggu dan azurite. Tapi emas jarang terjadi dalam studi mikroskopis dan kalkopirit dan sfalerit kelimpahan. Perubahan terkait dengan mineralisasi di daerah penelitian adalah perubahan propilitik dan perubahan temperatur argilik rendah oleh studi difraksi liat analisis petrografi dan X-rary mineral berorientasi.

The Sorepisa prospect area is located at the eastern part of the Sumbawa Island, Indonesia. The mineralization of the research area is mainly structural control and the trend direction of the all quartz veins is mainly NW-SE and NE-SW direction. The mineralization of the research area is investigated by petrographic study, ore mineralogy microscopic study, X-ray fluorescence method for geochemistry and X-ray diffraction oriented clay mineral analysis for alteration mineralogy associated with mineralization. According to the Na2O+K2O vs SiO2 diagram and Ti/Zr vs Nb/Y diagram, the geochemical characteristics of the host rock in the research area show basalt, basaltic andesite, andesite to dacite series and basaltic/andesite and andesite field. On the other hand, according to the Cr-Y diagram, the vein host rock in the research area is included in the volcanic arc basalt field and within the plate basalt field. The ore mineral composition of the research area is gold, silver, galena, pyrite, chalcopyrite, sphalerite, chalcocite, goethite, malachite and azurite. But according to the microscopic study, gold is rarely occurred and abundant in chalcopyrite and sphalerite. According to the study of petrographic and X-rary diffraction oriented clay mineral analysis, the alteration associated with mineralization in the research area is prophylitic alteration and low temperature argillic alteration.

Kata Kunci : Bijih mineralogi dan geokimia dari deposit epitermal polimetalik, Sorepisa prospek kawasan, Indonesia.