THE CHARACTERISTIC OF GRANITOID ALTERATION AND MINERALIZATION IN TOBOALI, BANGKA SELATAN REGENCY

• Main Author: Fergiawan, Dityas
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/72578
• Institution: Institut Teknologi Bandung

The study area is located in Toboali District, South Bangka Regency, with an area of 30.54 km2. Based on previous studies, it has been proven that the enrichment of rare earth elements and sedimentary tin in study location is present, but very little research has been done on its alteration and primary mineralization. The research conducted by the author aims to identify the geology, geomorphology, geological structure, alteration and mineralization of the study area. Observations were made at 62 points which were then subjected to petrographic and mineragraphic analysis for selected altered rock and vein samples. Geometry observations and plane measurements are specifically made for the presence of veins. The main existing geological structure is a dextral strike-slip fault and some minor faults. The lithology of the study area is in the form of granite unit, alluvial deposit unit, and mining disposal unit. Alteration in the study area occurs in granite lithology which is divided into four zones namely albitization zone (Alteration Zone of Quartz + Albite + Sericite ± Orthoclase), grisenization zone (Alteration Zone of Quartz + Muscovite + Sericite ± Clay), tourmalinization zone (Alteration Zone of Quartz + Tourmaline + Iron Oxide ± Topaz), and sericitization zone (Alteration Zone of Quartz + Sericite + Microcline ± Clay). Ore mineralization occurs in three phases. Chalcopyrite, sphalerite, galena, pyrite and cassiterite mineralized in the first phase. Covelite, magnetite, and ilmenite occurred in the second phase. Hematite is present as a weathering/supergene mineral. The veins in the study area occur in three geometries, sheeted veins trended NNW-SSE, lode veins trended WNW-ESE and flexure vein trended WNW-ESE. The NNW-SSE trending stress controls the fractures that form veins in the study area initiated by the presence of a dextral strike-slip fault in the study area..