We analyzed the chemical and isotopic composition of the geothermal fluids from the Hatchobaru geothermal field in the Kyushu Island, Japan. Fluid chemistry showed similarity with that reported in earlier studies. Chemical geothermometry provided an estimated reservoir temperature of 250–300 °C. Helium and carbon isotopic ratios of the steam is likely to reflect the signature of the magmatic heat source. The apparent equilibrium temperature for carbon isotope exchange between CO2 and CH4 was 375–430 °C. The sulfur isotope data were in accordance with the idea that an acidic Cl-SO4-type fluid was modified from a neutral Cl-type fluid.
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Geotechnical Engineering and Engineering Geology