Type of Mineral Deposits on Alteration Rocks using Petrography, X-Ray Fluorescence (XRF), and X-Ray Diffraction (XRD) Method in Geothermal Prospect in Tiouw Village, Maluku

Indonesia is a country with abundant geothermal energy potential. One of the locations that have potential geothermal energy sources is Tiouw Village, Saparua, Central Maluku. This study was conducted on the types of mineral deposits using the petrographic method, X-Ray Diffraction (XRD), and X-Ray Fluorescence (XRF). Based on the results of petrographic analysis and XRD, rock samples 1, 2, and 3 of Tiouw include andesite igneous rocks with propylitic alteration type. While sample 4 is dacite igneous rock with argillic alteration type. Each rock sample has a mineral set of kaolinite, chlorite, quartz, cristobalite, epidote, and plagioclase. The XRF results showed the highest chemical composition of SiO2, followed by Al2O3 and K2O. This mineral content can indicate the subsurface temperature of the geothermal field in the range of 200–300 ºC with varying salinity, pH close to neutral, and low permeability. This interpreted that the type of mineral deposits in Tiouw Village was high sulfidation epithermal deposits. DOI: http://dx.doi.org/10.17977/um024v4i22019p03

ANALISIS TERMAL DI DAERAH PROSPEK PANAS BUMI PASEMA AIR KERUH, KABUPATEN EMPAT LAWANG, SUMATERA SELATAN

Temperature measurements have been done in the prospect area of geothermal Pasema Air Keruh, District Empat Lawang, South Sumatra, to determine the temperature distribution on subsurface. Temperature measurement in monitoring and mapping is done on an area of 800 m x 800 m with two different locations, Penantian and Air Keliansar. Retrieval data of temperature measurement using a temperature sticks and electronic thermometer incorporating a thermistor as a sensor such as IC LM35. The working principle of this instrument is that the physical phenomena detected temperature sensor is converted into electrical signals in the potential difference, then converted in degrees Celsius. The results of measurements of temperature monitoring at the Penantian obtained average surface temperatures between 26,5 oC � 29,1 oC while for Air Keliansar obtained average surface temperature average between 27,3 oC � 30,5 oC. Distribution of heat on subsurfaces is calculated by solving the heat conduction equation (Laplace) with a finite difference method that has been constructed (known as the Liebmann method). The modeling assumes that twodimensional objects shaped the plate. The results of modeling heat source on subsurface with finite difference methods estimate the temperature reservoir in Penantian is 400 oC at a depth of 1100 m, while for Air Keliansar the temperature reservoir is 400 oC at a depth of 1300 m