TY - JOUR
T1 - Water geochemistry and soil gas survey at Ungaran geothermal field, central Java, Indonesia
AU - Phuong, Nguyen Kim
AU - Harijoko, Agung
AU - Itoi, Ryuichi
AU - Unoki, Yamashiro
N1 - Funding Information:
This study was supported by AUN/SEED-Net program, JICA (Japanese International Cooperation Academic) and Gadjah Mada University, Indonesia . The authors thank Prof. Sachihiro Taguchi of Fukuoka University for his help to analyze stable isotope of water samples.
PY - 2012/6/1
Y1 - 2012/6/1
N2 - A soil gas survey for radon (Rn), thoron (Tn), CO 2, and mercury (Hg), and the chemical analysis of hot spring waters, were undertaken in the Ungaran geothermal field, Central Java, Indonesia. The results of soil gas surveys indicate fault systems trending NNE-SSW and WNW-ESE. Particularly high CO 2 concentrations (>20%), and high Hg concentrations were detected in vicinity of the fumaroles. Emanometries of Rn, Tn and CO 2 also conclusively identified the presence of a fracture zone for the migration of geothermal fluid. The Hg results infer that the up-flow zone of high temperature geothermal fluids maybe located in the north of fumaroles in the Gedongsongo area (near the collapse wall). Chemistry of thermal springs in the up-flow zone are acid (pH=4) and show a Ca-Mg-SO 4 composition. The thermal waters are mainly Ca-Mg-HCO 3 and Ca-(Na)-SO 4-HCO 3 types near the fumarolic area and are mixed Na-(Ca)-Cl-(HCO 3) waters in the south east of Gedongsongo. The δ 18O (between -5.3 and -8.2‰) and δ (between -39 and -52‰) indicate that the waters are essentially meteoric in origin. A conceptual hydro-geochemical model of the Gedongsongo thermal waters based on the soil gas, isotope and chemical analytical results, was constructed.
AB - A soil gas survey for radon (Rn), thoron (Tn), CO 2, and mercury (Hg), and the chemical analysis of hot spring waters, were undertaken in the Ungaran geothermal field, Central Java, Indonesia. The results of soil gas surveys indicate fault systems trending NNE-SSW and WNW-ESE. Particularly high CO 2 concentrations (>20%), and high Hg concentrations were detected in vicinity of the fumaroles. Emanometries of Rn, Tn and CO 2 also conclusively identified the presence of a fracture zone for the migration of geothermal fluid. The Hg results infer that the up-flow zone of high temperature geothermal fluids maybe located in the north of fumaroles in the Gedongsongo area (near the collapse wall). Chemistry of thermal springs in the up-flow zone are acid (pH=4) and show a Ca-Mg-SO 4 composition. The thermal waters are mainly Ca-Mg-HCO 3 and Ca-(Na)-SO 4-HCO 3 types near the fumarolic area and are mixed Na-(Ca)-Cl-(HCO 3) waters in the south east of Gedongsongo. The δ 18O (between -5.3 and -8.2‰) and δ (between -39 and -52‰) indicate that the waters are essentially meteoric in origin. A conceptual hydro-geochemical model of the Gedongsongo thermal waters based on the soil gas, isotope and chemical analytical results, was constructed.
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U2 - 10.1016/j.jvolgeores.2012.04.004
DO - 10.1016/j.jvolgeores.2012.04.004
M3 - Article
AN - SCOPUS:84860145131
SN - 0377-0273
VL - 229-230
SP - 23
EP - 33
JO - Journal of Volcanology and Geothermal Research
JF - Journal of Volcanology and Geothermal Research
ER -