STUDY OF GEOLOGY AND HYDROTHERMAL MINERALIZATION IN MONTON AREA, KECAMATAN ARUT UTARA, KABUPATEN KOTAWARINGIN BARAT, KALIMANTAN TENGAH PROVINCE.

• Main Author: Azzam Azzahidi, Abdullah
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/24893
• Institution: Institut Teknologi Bandung

Administratively, Monton Area located in Kecamatan Arut Utara, Kabupaten Kotawaringin Barat, Kalimantan Tengah Province. Monton Area regional geology consists of Trias volcaniclastic intruded by Jura Mandahan granite and covered by Late Miocene sediment. Purpose of this research is to understand the geological setting and hydrothermal mineralization process in the area. This study covers 64,35 km2 area, with UTM coordinate in 9766000 – 9773000 mU and 608420 – 619700 mT (datum WGS84 zone 48S). These research methods comprise topography map and SRTM image analysis, rock sampling and field observation to determine distribution of lithology, alteration zone, and mineralization in the area. Area observation validates by sample analysis with petrography, mineragraphy, and SWIR (Short Wavelength Infrared) analysis. Research area divided into five geomorphological units, consists of Alluvial Plain unit, Denudational Plain unit, Anticline Ridge unit, Homocline Ridge unit, and Intrusion Hills unit. Geology of research area divided into seven units, consists of Aluvial unit, Pyroxene Andesite unit, Dacite unit, Hornblende Andesite unit, Andesite unit, Sandstone unit, Tuff unit. Geological structure in research area is secondary structure, consists of Monton Dextral Normal Fault, Merundau Thrust Sinistral fault, and Mekahing Thrust Sinistral Fault. Hydrothermal alteration in the research area divided into four zones of chlorite – illite – epidote zone, halloysite – kaolinite – illite zone, sericite – quartz zone, and kaolinite – pyrophillite zone. Mineralization in research area interpreted as volcanogenic massive sulphide (VMS) deposits divided into three zones of chalcopyrite – bornite zone, galena – sphalerite zone, and pyrite zone. The geological histories of research area generally consist of two phases. First phase, Pre Tertiary phase started from forming of Tuff Unit and sedimentation of Sandstone Unit syngenetic with volcanism which forming intermediate to felsic igneous rock with mineralization of VMS as stratform in sandstones. Tectonics caused uplifting and volcanism makes of structural geology and hydrothermal alteration in research area. Second phase, Tertiary phase Sintang Intrusion in Oligocene forming Andesite Pyroxene Unit in research area.