Preliminary assessment of low to moderate geothermal system over Mt. Pancar area (Bogor) based on remote sensing and geochemical studies

Abstract

Preliminary assessment of MT Pancar was carried out using remote sensing and geochemical studies. Remote sensing can be applied as the first guidance in the exploration stage of developing geothermal prospect area. It is usually used to provide an overview of geothermal system before conducting geological survey. In this research, remote sensing using DEM ASTER was performed to give information about lithology and structure of Mt. Pancar geothermal prospect area. Delineation of several lithological unit is based on texture and pattern of the remote sensing image. After field checking, four lithological units have been confirmed covering Mt Pancar area, such as Pancar andesite, Anak Pancar andesite, Kencana-Limo volcanic breccia and Jatiluhur shale. Furthermore, indication of geological structures in NE-SW and NW-SE trend caused by sinistral movement of Baribis thrust is also successfully imaged by remote sensing analysis. The structures probably control the existence of Kawah Merah and Kawah Hitam hotsprings in the Mt Pancar area. Moreover, geochemical studies were also carried out by taking water samples and measuring the temperature and pH. The results show that the temperature of Kawah Merah, Kawah Hitam and Kawah Putih hotsprings are 68.4°C, 58.1°C and 47°C, respectively. All of the hotsprings are classified as neutral hotsprings with pH range of 6.4 to 7.7. It indicates that the whole hotsprings are an outflow zone of Mt. Pancar geothermal system. In addition, based on morphological feature, the heat source is inferred beneath the center of Mt. Pancar. Based on Na/K geothermometry, the subsurface temperature in Mt Pancar geothermal prospect area is estimated in the range of 180 to 190°C. Therefore, Mt Pancar geothermal area can be classified as a low to moderate geothermal system.