KONTROL BATUAN SAMPING TERHADAP KADAR Au PADA BATUAN ALTERASI BERDASARKAN ANALISIS GEOKIMIA PADA DAERAH KP PT ANTAM, TBK DI DAERAH KUBANG CICAU, KECAMATAN NANGGUNG, KABUPATEN BOGOR, JAWA BARAT

Abstract

deposits formed because of contact metasotism process and hydrothermal solution, while concentration mechanically produces placer deposit. Pongkor is one of West Java area that has pretty high gold (and silver) deposit. Pongkor’s gold-silver deposit found in adularia carbonate quartz vein low sulfidation epithermal which is found by PT. Aneka Tambang (ANTAM) on year 1981. Hydrothermal systems can be defined as circulation of a hot temperature liquid (temperature between 50Ε- >500Ε), laterally and vertically on various temperature and pressure, below the earth surface (according to Piraino, 1992). Interaction between hydrothermal fluids with rocks that passed through by the fluid (wall rocks) will cause an alteration on primary minerals to alteration minerals. On certain balance condition, hydrothermal process will produce a group of certain minerals known as mineral assemblage, which show the type of alteration. Kubang Cicau zone, Nanggung territory, Bogor regency, West Java province is one examples of PT. ANTAM’s KP area which strongly altered, therefore on the altered rocks can also be found the Au value. In this area there are two alteration types that strongly developing, those are argilic and prophilitic alteration type, which consist of different Au value, therefore a research has been conducted through the Atomic Absorption Spectometry to find out the differences of Au value between each of alteration type, so can be find out if an alteration type controls on wall rock’s Au value. After a research and the Atomic Absorption Spectometry test result analysis on each of wall rocks that has been altered, either argilic or prophilitic, a conclusion can be made which is, although the values between argilic and prophilitic are different, but the difference amount of Au value is not considered significant. Therefore the conclusion of this research is: alteration type does not control the Au values on wall rocks.