10:45 〜 12:15
[AHW19-P09] 温泉水の地球化学的特徴と地下温度の推定
Hot springs are widely distributed in the Japanese Island, corresponding to high potential geothermal resource areas. The chemical composition of hot spring water reflects the origin and source, the chemical reaction processes with surrounding rocks, and the thermal history of underground water. In this study, the chemical and isotopic compositions of hot spring waters were analyzed over a wide area in Japanese Island to clarify the geochemical characteristics and origin of hot spring waters, and the subsurface temperatures were determined using a geochemical thermometer to examine the geological factors constraining heat potential.
Hot spring waters were classified according to their geochemical characteristics and origins using hexadiagrams and trilinear diagrams, and their subsurface temperatures were further determined using Na-K thermometers, Na-K-Ca thermometers, and SiO2 thermometers. Hot spring waters in areas with high temperatures are mainly of, meteoric water origin and characterized as rich in Na-HCO3, Ca-SO4, Ca-HCO3, and Na-SO4, indicating that many of them are affected by volcanic gases and volcanic fluids. These hot spring waters are often found in andesite and basaltic andesite areas, with recent volcanic activities, suggesting that the influence of the heat from volcanoes is essential for water geochemistry. Relatively low-temperature hot spring waters are characterized by their high Na-Cl content and the relatively large contribution of seawater and fossil seawater, and are often found in areas where mixed rocks other than andesite and basaltic andesite, accretionary complexes, and coastal sediments are developed. The subsurface temperature in geothermal areas is strongly influenced by the distribution of magma, and the hot spring water has been altered by the dissolution of large amounts of magma-derived constituents.
Hot spring waters were classified according to their geochemical characteristics and origins using hexadiagrams and trilinear diagrams, and their subsurface temperatures were further determined using Na-K thermometers, Na-K-Ca thermometers, and SiO2 thermometers. Hot spring waters in areas with high temperatures are mainly of, meteoric water origin and characterized as rich in Na-HCO3, Ca-SO4, Ca-HCO3, and Na-SO4, indicating that many of them are affected by volcanic gases and volcanic fluids. These hot spring waters are often found in andesite and basaltic andesite areas, with recent volcanic activities, suggesting that the influence of the heat from volcanoes is essential for water geochemistry. Relatively low-temperature hot spring waters are characterized by their high Na-Cl content and the relatively large contribution of seawater and fossil seawater, and are often found in areas where mixed rocks other than andesite and basaltic andesite, accretionary complexes, and coastal sediments are developed. The subsurface temperature in geothermal areas is strongly influenced by the distribution of magma, and the hot spring water has been altered by the dissolution of large amounts of magma-derived constituents.