KARAKTERISTIK ENDAPAN EMAS OROGENIK SEBAGAI SUMBER EMAS PLACER DI DAERAH WUMBUBANGKA BOMBANA, SULAWESI TENGGARA
| Main Authors: | , Fadlin, , Dr. rer,nat. Arifudin Idrus, ST., MT. |
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| Format: | Thesis NonPeerReviewed |
| Terbitan: |
[Yogyakarta] : Universitas Gadjah Mada
, 2011
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| Subjects: | |
| Online Access: |
https://repository.ugm.ac.id/90323/ http://etd.ugm.ac.id/index.php?mod=penelitian_detail&sub=PenelitianDetail&act=view&typ=html&buku_id=53246 |
Daftar Isi:
- The placer gold discovering in Tahi Ite River, Bombana (Kompas, September 18th 2008) was quite unique, because it is not common in Indonesia to find gold deposit in the metamorphic rocks. This deposit is supposed as orogenic gold deposit, because the study area is controlled by the intensive geological structures with the metamorphic rock as the host rock. This study is aimed to determine the alteration zone, mineralisation and characteristic of the gold deposits. Geological mapping, petrography, mineragraphy, X-Ray Diffraction (XRD), AAS (fire assay), and fluid inclusion analyses have been employed in order to discover the alteration types, mineralisation and characteristics of gold deposit. The alteration types in the study area consist of: silicification, argilic (clay ± silica), chlorite-carbonate, and carbonisation. Based on the AAS (fire assay) analysis, the highest gold concentrations were found in several samples such as: WB-02-C1 (2.52 ppm), WB- 02-C2 (1.06 ppm), WB-03 (0.94 ppm), and the WB-04 (1.31 ppm). There are three veins generation in the study area. The first vein generation is parallel to the foliation, it was formed at the temperature of 221,9oC with the salinity value of 7.17 wt,% NaCl equivalent. The second vein generation is a quartz vein that cutted the foliation, it was formed at temperature of 188.4°C with the salinity value of 3.87 wt,% NaCl equivalent. The third generation is calcite-quartz vein which indicated the last phase of the orogenic gold in the study area, it was formed at the temperature of 138.2oC with the salinity value of 1.91 wt.% NaCl equivalent. The quartz veins in the study area have particular characteristic including massive, sometimes segmented and sigmoidal in texture. Another important founding in this study is the orogenic gold deposits in this area lies on the transition zone between the epizonal and mesozonal at the depth of approximately 5-6 kilometers, on the green schist facies.