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Alteration Minerals and quartz textures of Epithermal quartz veins at Soripesa Prospect area, Indonesia
- The Soripesa prospect area is located at Maria village, Wawo district, Bima regency, West Nusa Tenggara Province, Sumbawa Island, Indonesia. This area is mainly occupied by andesitic volcaniclastic rocks, daciticvolcaniclastic rocks, bedded and fossiliferous limestone, and Quaternary volcanic rocks. Representative samples, collected from near five quartz veins were selected to make thin sections. Thin sections were analyzed using a polarizing lightmicroscope. Selected nine samples were used to identify the quantitative mineralogy. XRD data were obtained by using a Rigaku RINT 2100 at the Earth Resources Engineering Department, Kyushu University, Japan. The primary minerals of host rocks of the veins are quartz, orthoclase, plagioclase, pyroxene, amphibole minerals, mica and other mafic minerals. The common alteration minerals in this prospect area are quartz, epidote, chlorite, pyrite, illite, and smiectite. Minor amount of other alteration minerals arekaolinite, alunite, rutile, and anatase. Propyllitic alteration (epidote + chlorite) occurs in most host rocks of the veins.Most common quartz textures of those veins in the research area are primary textures (comb, colloform bands, and crustiform bands, zonal, cockade, and moss).Alteration mineral are altered under in terms of interaction of near-neutral chloride fluids and are crucial in distinguishing low-sulphidation types of epithermal systems.Quartz textures in this research belong to typical characters of low-sulphidation epithermal system and they can help to identify the morphology of veins such as face-controlled and parallel-controlled. Quartz textures indicate that the epithermal quartz veins in the Soripesa prospect area are formed at the near surface.
- Shwebo University Research Journal