The Metamorphic Rocks-Hosted Gold Mineralization At Rumbia Mountains Prospect Area In The Southeastern Arm of Sulawesi Island, Indonesia

Abstract

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.

Analisis Ketebalan Bawah Permukaan Endapan Mineral Grafit Alam di Kelurahan Watuliandu, Kecamatan Kolaka, Kabupaten Kolaka

“…(Rusmana, E;Sukarna, D;Haryono, E;Simandjuntak, Surono and Sukido, 1993;Surono, 2010). Beberapa formasi batuan tersebut membawa bahan galian berharga antara lain Kompleks Pompangeo dan Formasi Langkowala membawa mineral emas (Makkawaru and Kamrullah, 2009;Idrus et al, 2011;Hasria, Idrus and Warmada, 2017), Kompleks ultramafik membawa endapan nikel laterit (Hamilton, 1979;Kamaruddin et al, 2018), dan endapan kromit, magnetit, Ni-sulfida, Ni-Fe, Cu-sulfida (Lintjewas, 2015;Sufriadin, Widodo and Thamrin, 2017) Kompleks Pompangeo dan Kompleks Mekongga merupakan kompleks batuan malihan yang terdiri dari sekis mika, sekis glakofan, sekis amfibolit, sekis klorit, rijang berlapis dengan sekis genesan, pualam dan batugamping meta, filit, kuarsit, dan batu sabak. Penyebaran dari kompleks batuan malihan ini cukup luas dengan perkiraan luasan menempati sekitar 50% dari total luas wilayah Lengan Tenggara Sulawesi.…”

“…Keberadaan kompleks batuan malihan ini memungkinkan akan mengandung beberapa jenis mineral-mineral berharga salah satunya adalah grafit. (Hasria, Idrus and Warmada, 2017;Hamimu et al, 2019).…”

Alteration Alteration, Mineralization and Geochemistry of Metamorphic Rocks Hosted Hydrothermal Gold Deposit at Rumbia Mountains, Bombana Regency, Southeast Sulawesi, Indonesia

“…Chalcopyrite is associated with pyrite while cinnabar is typically pinkish red in color and commonly occurred in the form of mineralized layers along foliations of the metamorphic rocks. Pyrite, hematite, cinnabar and stibnite are genetically closely related to gold mineralization (Hasria et al, 2017).…”

The Facies and Metamorphism Types Determination of Metamorphic Rock in The Part of Mekongga Complex

“…The process is known as the metamorphism process. According to Hasria et al (2017) metamorphic rock development is a result of magma and pressure. According to (Ca et al, 2019) one of the basement rocks envolved is metamorphism.…”