MINERALIZATION PARAGENESIS OF PORPHYRY-INTERMEDIATE SULFIDATION EPITHERMAL DEPOSIT IN DOUP AREA, KOTABUNAN SUBDISTRICT, EAST BOLAANG MONGONDOW REGENCY, NORTH SULAWESI

• Main Author: Aji Wiwatama, Affan
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/85812
• Institution: Institut Teknologi Bandung

Indonesia is a country with great potential resources and gold reserves, one of which is on the Sulawesi Island. The research area is located in the Doup Area, Kotabunan District, East Bolaang Mondondow Regency, North Sulawesi Province which has gold mineralization prospects. The purpose of this study is to determine the geological conditions, geomorphology, stratigraphy, and structure of the research area; to know the types and characteristics of alteration and mineralization in the research area, and to know the paragenesis of mineralization in the research area. As 72 rock surface samples, 2 primary boreholes data, 4 secondary boreholes data were used for analysis in this study. The methods used include thin incision petrography, polished incisions, spectroscopic analysis, and x-ray flourescene (XRF) analysis. Based on the results of the research, the research area consists of eleven lithological units, namely limestone unit, tuff unit, andesite intrusion unit, diorite quartz intrusion unit, tonalite unit, sandstone-conglomerate unit, dacite lava unit, andesite intrusion 2 unit, epiclastic breccia units, volcanic conglomerate unit, alluvium-colovium unit. The structure develops in the northeast-southwest and northwest-southeast directions. The alteration zones found are the magnetite + biotite ± K-felspar zone, the magnetite + chlorite ± epidot, and chlorite zone as a characteristic of the porphyry system, as well as the sericite + chlorite + illite ± kaolinite and quartz + seritic + illite + pyrite zones as the characteristic zone of the intermediate sulfidation epithermal system that overprints the existence of the porphyry system. The paragenesis of minerals begins with the formation of magnetite in porphyry veins, followed by the formation of pyrite and chalcopyrite. The veins in the porphyry system are cut by basemetal veins which indicate that the mineral pyrite initiates the formation of these veins, followed by galena, sphalerite, chalcopyrite, gold, covelite, and hematite.