GEOCHEMICAL INVESTIGATION OF HOT SPRINGS IN THE BUR NI GEUREUDONG GEOTHERMAL PROSPECT AREA, ACEH-INDONESIA

Abstract

The Bur Ni Geureudong volcanic complex is a potential area for geothermal development and utility. This volcanic complex is situated in northern Sumatra, Aceh Province, Indonesia. Geothermal potential in this area is manifested by several hot springs discharged in the Pinto Rime Gayo (PRG), Simpang Balek (SB), Uning Bertih (UB), and Silih Nara (SN) springs. All springs have a neutral pH and a surface temperature ranges from 34.10 to 67.11ºC. A geochemical investigation was conducted on the hot springs to understand the hydrochemistry of the geothermal fluid and estimate the reservoir temperature of the geothermal area. This investigation was an exploration study of geothermal resources in the area. Hot waters in the PRG, SB, UB, and SN springs were collected and analyzed in May 2018 to identify the cations and anions contained. Piper and Cl-SO 4 -HCO 3 diagrams have been plotted to characterize the geothermal fluid. Na/K geothermometer has been applied to calculate the temperature of the geothermal reservoir. Isotope analysis has also been conducted to estimate the origin of the fluid. This research discovered that the major element of the water demonstrates the various geothermal water types. The PRG spring contains Na-K-Cl water, whereas the SN spring contains diluted Cl-HCO 3 water with mixed cation concentrations of Ca, Mg, Na, and K. The waters in SB and UB are a mixed form of Cl-HCO 3 -SO 4 waters. According to the δD and δ 18 O relationship , t he genesis of geothermal fluids is hydrothermal fluids of meteoric water. Based on the Na/K geothermometer, the reservoir temperature of the Bur Ni Geureudong geothermal system is a range of 171-289ºC which is indicated as a high enthalpy system (>225ºC). It can be concluded the Bur Ni Geureudong geothermal region is recognized by this study as a promising source of renewable energy. Future work on geothermal exploration and utilization is expected to expand on the framework established by this present study.