The Metamorphic Rocks-Hosted Gold Mineralization At Rumbia Mountains Prospect Area In The Southeastern Arm of Sulawesi Island, Indonesia
Recently, in Indonesia gold exploration activities are not only focused along volcanic-magmatic belts, but also starting to shift along metamorphic and sedimentary terrains. The study area is located in Rumbia mountains, Bombana Regency, Southeast Sulawesi Province. This paper is aimed to describe characteristics of alteration and ore mineralization associated with metamorphic rock-related gold deposits. The study area is found the placer and primary gold hosted by metamorphic rocks. The gold is evidently derived from gold-bearing quartz veins hosted by Pompangeo Metamorphic Complex (PMC). These quartz veins are currently recognized in metamorphic rocks at Rumbia Mountains. The quartz veins are mostly sheared/deformed, brecciated, irregular vein, segmented and relatively massive and crystalline texture with thickness from 1 cm to 15.7 cm. The wallrock are generally weakly altered. Hydrothermal alteration types include sericitization, argillic, inner propylitic, propylitic, carbonization and carbonatization. There some precious metal identified consist of native gold and ore mineralization including pyrite (FeS2), chalcopyrite (CuFeS2), hematite (Fe2O3), cinnabar (HgS), stibnite (Sb2S3) and goethite (FeHO2). The veins contain erratic gold in various grades from below detection limit <0.0002 ppm to 18.4 ppm. Based on those characteristics, it obviously indicates that the primary gold deposit present in the study area is of orogenic gold deposit type. The orogenic gold deposit is one of the new targets for exploration in Indonesia
Groves, D. I., Goldfarb, R. J., and Robert, F., 2003. Gold deposit in metamorphic belts: Overview or current understanding, outstanding problems, future research, and exploration significance. Economic Geology, 98, p.1-29.
Groves, D. I., Goldfarb, R. J., Gebre-Mariam, M., Hagemann, S. G., and Robert, F., 1998. Orogenic gold deposit: A proposed classification in the context or their crustal distribution and relationship to other gold deposit types. Ore Geology Review, 13, p.7-27.
Idrus, A., 2009. Potensi Sumberdaya Mineral Bijih pada Busur Magmatik Sulawesi bagian Barat dan Utara, Invited speaker on National Seminar “Geologi Sulawesi dan Prospeknya”, Makassar, 3 Oktober 2009, 26pp.
Idrus, A., Fadlin., Prihatmoko, S., Warmada, I.W., Nur, I., and Meyer, F.M., 2012. The metamorphic rock-hosted gold mineralization at Bombana, Southeast Sulawesi: a new exploration target in Indonesia. Jurnal Sumber Daya Geologi, (22) 1: 35-48.
Idrus, A., Hakim, F., Warmada, I.W., Aziz, M., Kolb, M and Meyer, F.M., 2015. Geology and ore mineralization of Neogene sedimentary rock hosted LS epithermal gold deposit at Paningkaban, Banyumas Regency, Central Java, Indonesia.Journal of Southeast Asian Applied Geology,Volume 7(2), pp. 73-79.
Idrus, A., Kolb, J., and Meyer, F.M., 2007. Chemical composition of rock-forming minerals in copper-gold- bearing tonalite porphyry intrusions at the Batu Hijau deposit, Sumbawa Island, Indonesia: Implications for crystallisation conditions and fluorine-chlorine fugacity, Special Issue. Resource Geology, 57 (2), p.102-113.
Idrus, A., Nur, I., Warmada, I W., and Fadlin., 2011. Metamorphic rock-hosted orogenic gold deposit type as a source of Langkowala placer gold, Bombana, Southeast Sulawesi. Jurnal Geologi Indonesia, (6) 1: 43-49.
Idrus, A., Prihatmoko, S., Hartono, GH., Idrus., Ernowo, Franklin, Moetamar, Setiawan, I., 2014. Some Key Features and Possible Origin of the etamorphic Rock-Hosted Gold Mineralization in Buru Island, Indonesia. Indonesian Journal on Geoscience, 1, p. 9-19.
Imai, A. and Ohno, S., 2005. Primary ore mineral assemblage and fluid inclusion study of the Batu Hijau porphyry Cu-Au deposit, Sumbawa, Indonesia. Resource Geology, 55, p.239-248.
O'Connor, F.A., Lucey, B.M., Batten, J.A., and Baur, D.G., 2015. The financial economics of gold-A survey. International Review of Financial Analysis, 1-20p.
Simandjuntak, T.O., Surono, and Sukido., 1993. Peta Geologi Lembar Kolaka, Sulawesi, skala 1 : 250.000. Pusat Penelitian dan Pengembangan Geologi, Bandung.
Surono., 2013. Geologi Lengan Tenggara Sulawesi. Badan Geologi, Kementerian Energi dan Sumber Daya Mineral. Bandung, 169p.
Wadji, M.F., Santoso, S.T.J., Kusumanto, D., and Digdowirogo, S., 2011. Metamorphic Hosted Low Sulfidation Epithermal Gold System at Poboya, Central Sulawesi : A General Descriptive Review, Proceedings of The Sulawesi Mineral Seminar, Manado 28-29 November 2011, p. 201-210.
Warmada, I W., 2003. Ore mineralogy and geochemistry of the Pongkor epithermal gold-silver deposit, Indonesia. Dissertation. Papierflieger, Clausthal-Zellerfeld. ISBN: 3-89720-658-7
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