Past and Present Subsurface Thermal Structures of the Kirishima Geothermal Area, Japan

Abstract

The homogenization temperature of fluid inclusion in hydrothermal quartz, anhydrite and calcite found in cores and cuttings from the Kirishima geothermal area, Japan. The results show that the homogenization temperatures have a wide range at each depth, usually 45 to 100°C for the inclusions form the North Kirishima geothermal field, and 20 to 45°C for those from the West Kirishima geothermal field. The distribution of homogenization temperature suggests that the Kirishima geothermal area has cooled down to some extend, and the cooling degree in the North Kirishima field is larger than that of the West Kirishima field. The cooling bean to progress from the margin of Kirishima Volcano, and seems to have been controlled by fault systems in the area.