STUDY OF ALTERATION AND MINERALIZATION OF PROSPECT-S AREA, TANAH SIANG SELATAN, CENTRAL KALIMANTAN

• Main Author: GUSNELLY, EMILIA
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/52611
• Institution: Institut Teknologi Bandung

Prospect-S is a prospect area in the work contract area of PT. Indo Muro Kencana, located in Tanah Siang Selatan District, Murung Raya Regency, Central Kalimantan Province. This study aims to determine the geological conditions of the research area including lithology, the geological structure and the distribution of alteration and mineralization. The method is used in this study is field mapping, analysis of thin section of altered rock, analysis of polished section of vein, and processing of geochemical assay data. There are two lithological units, namely the andesitic tuff unit intruded by the andesite unit. The geological structure developed in the study area is a dextral strike slip structure with NE direction, and then develop to pattern direction like NW-SE, N-S and WNW-ESE. Both rock units undergo alteration of chlorite + clay minerals + quartz + pyrite ± calcite with moderate - strong intensity, sericite alteration + quartz + clay minerals ± pyrite with moderate - very strong intensity and silicification. The vein stages that occur in the research area consist of 5 stages, among others; microcrsystalline quartz infill, hydrothermal breccia, microcrsytalline quartz infill + base metal sulfide infill + sulfosalt, crystalline quartz infill + base metal infill, carbonate infill. The ore minerals present in the research area include pyrite, sphalerite, chalcopyrite, galena, tenantite-tetrahedrite, electrum and native Au. Based on the Pearson correlation value, Pb elements have a very strong positive correlation with Zn elements, that is indicated by the presence of sphalerite associated with galena. Both, Pb and Zn elements have very weak – weak positive correlations with Au and Ag elements, this is indicated by the presence of galena and sphalerite minerals that sometimes associated with native Au. The Au/Ag ratio of the study area is 1/23. Based on the character of the alteration and mineralization minerals present in the study area, the study area is an intermediate sulfidation epithermal deposit.