Geomagnetic and Geochemical Observations in Mt. PandanVolcano Hosted Geothermal Area, East Java, Indonesia
Sukir Maryanto1*, Wenti M. Maubana2, Ahmad Nadir3
1*Brawijaya Volcano and Geothermal Research Center, UniversitasBrawijaya, Malang 65415, East Java, Indonesia
2Magister Program, Department of Physics, UniversitasBrawijaya, Malang 65415, East Java, Indonesia
3Instrumentation Laboratory, UniversitasBrawijaya, Malang 65415, East Java, Indonesia
Corresponding author : sukir[at]ub.ac.id
Abstract
Geomagnetic and Geochemical observations have been conducted to identify the geothermal potential of Mt. Pandan Volcano Hosted Geothermal, East Java, Indonesia. Firstly, the magnetic survey was performed using PPM G-856 and running on 80 magnetic stations that cover an area of 9x10 km2. The measurement stations cover two hot springs, Jari and Banyukuning in the Mt. Pandan. The result showed that total magnetic intensity ranged from 446.7nT to 526.3nT. The residual anomaly of contour map revealed that geothermal reservoir was suspected in an area with low magnetic intensity around the hot spring and identified as the volcanic braccia and tuffaceous sandstone. The tentative model from magnetic residual anomaly can show location, depth, and thickness of the geothermal reservoir. The flow pattern the reservoir to manifestation, show the alleged presence of a secondary structure. This indicates that Jari and Banyukuning manifestation have different reservoirs. Furthermore, the geochemistry method has been done to analyze the characteristics of geothermal fluid in this area. Water sample was collected at two hot spring, Jari (Selo Gajah) and Banyukuning. The geochemical data was process using the spectrophotometric method to analyze the concentration of anion and cations that contained in hot springs water. The Geochemical analysis can identify the type and characteristics of the fluid to estimate the reservoir temperature. The results show that the type of water in geothermal system from mount Pandan area are cloride and bicarbonate water. Meanwhile, the geothermometer analysis for Na-K-Ca shows the average of reservoir temperature is arround 130 C and classified into medium entalphy system.
Keywords: Geomagnetic, Geothermal, Mount Pandan, geochemistry, reservoir temperature, medium enthalpy
Topic: Renewable Energy