Interpretation and Analysis of Hydrothermal Alteration Minerals Distribution Zone Based on Remote Sensing and Geographic Information System (GIS) for Mount Patuha and Surrounding Area, Bandung Regency, West Java

The area of Mount Patuha and its surroundings is an area of hilly and mountainous morphology with a slope of around 15%–45%. Administratively, this area is included in three subdistricts, namely Rancabali Subdistrict, Pasir Jambu Subdistrict, and Ciwidey Subdistrict. The Mount Patuha area and its surroundings are included in the Quaternary Volcanoes, part of Java Island's southern mountains. This area shows many manifestations, such as hot springs, gases, fumaroles, and hydrothermal altered rocks caused by the reaction of hydrothermal fluids with rocks. The Patuha Geothermal Field in this area has been and is being developed by PT. Geo Dipa Energi as a geothermal power plant. This study aims to map the distribution of hydrothermal altered rocks or alteration minerals in the study area. The remote sensing method is carried out by combining the wavelengths of the Landsat 8 OLI/TIRS image band channels to obtain the zoning distribution of hydrothermal or mineral alteration rocks, while DEM (Digital Elevation Model) SRTM data is interpreted to obtain morphological information in the study area. The combination of Landsat imagery that has been carried out is a composite RGB (red, green, and blue) band and Composite Band Ratio to obtain information on the recorded image. RGB band composite 5-6-7 provides information on the geological structure, rock texture, and the presence of altered rock; composite band 4-3-2 natural color provides information on geomorphology, geology, and vegetation; ratio band 4/2 provides information related to minerals Ferrugination (Limonite); ratio bands 5/6 provide information regarding Ferromagnesian minerals; Ratio Bands 6/7 provide information regarding Clay and Carbonate Minerals; and RGB 4/2, 6/7, 5, or 10 provide information regarding hydrothermal alteration minerals, vegetation in drainage, and altered rocks, as well as composite band 10-11-7, which provides information on silica-rich rocks. The results of this study can be used to obtain information on the distribution of hydrothermal alteration rocks or their alteration minerals in the study area. From this study, it can be concluded that the application of remote sensing methods can provide information on the distribution of hydrothermal alteration rocks or alteration minerals in the study area on a regional basis, so this data can be used as initial data in conducting exploration prior to field mapping