著者

加戸 裕也 上田 晃 中本 利正

出版者

一般社団法人日本地球化学会

雑誌

地球化学 (ISSN:03864073)

巻号頁・発行日

vol.50, no.4, pp.279-298, 2016-12-25 (Released:2016-12-25)

参考文献数

49

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Chemical compositions previously obtained from 333 hot springs in Ishikawa Prefecture were firstly examined for the geochemical characteristic. The Cl- concentration varies from 9 to 17,490 mg/L. Two geothermometers (Na+/K+ratio and SiO2 concentration) have been applied to estimate the subsurface temperatures with the chemical data and show that there are several high temperature areas (>150℃).Secondly, 29 hot springs and three river waters were newly collected from selected areas and analyzed for their hydrogen and oxygen isotopic compositions to also examine the source. The chemical and isotopic compositions indicate that the hot spring waters are a mixture of meteoric water, sea water (fossil sea water in a Green Tuff region) and volcanic fluid. The high temperature geothermal resources on the basis of the estimated subsurface temperature (ca. 200℃) may exist in the Hakusan area, the southern part of Ishikawa. The estimated geothermal resources in this area are ca. 60 MW. During geothermal power generation in this area, calcite is expected to precipitate in the reservoir and production wells according to the saturation indices for the hot spring waters and should be prohibited the precipitation.

著者

小路 翔子 笹木 康平 上田 晃 中本 利正

出版者

一般社団法人日本地球化学会

雑誌

地球化学 (ISSN:03864073)

巻号頁・発行日

vol.50, no.2, pp.97-114, 2016

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Chemical and isotopic (δD and δ¹⁸O) compositions of 30 hot spring waters and 5 river waters in Okuhida Hot Springs, Gifu, were investigated to examine the geochemical characteristics and geothermal resources. Most hot springs were of meteoric origin and of Na⁺–Cl^-・HCO₃^- and Na⁺–HCO₃^- types with low salinity (less than 30 meq/L). In the study area, meteoric water infiltrates into ground and is heated by magmatic source and enriched in Ca²⁺and HCO₃^- during interaction with underlying carbonate rocks. A part of the hot spring is enriched in CO₂ due to contribution of CO₂-rich volcanic fluid. The estimated underground temperatures by several geothermometers are 150 to 200℃ at the depth of <i>ca</i>. 1 km. The total geothermal resources in the study area are estimated to be <i>ca</i>. 400 MWe for producing the electricity. In the study area, most hot springs have been provided for bathing in hotels and a part of them (60℃, 3,000 L/min) has not been used. We provide this unused geothermal energy to apply for snow melting on road and room heating. For the safety use of geothermal resources in the study area, scaling problem was considered. On the basis of the saturation index of several minerals from the observed chemical compositions of hot spring waters, calcite scale is expected to be precipitated in the reservoir and in the production wells and should be considered to prohibit the precipitation.

著者

小路 翔子 笹木 康平 上田 晃 中本 利正

出版者

日本地球化学会

雑誌

地球化学 (ISSN:03864073)

巻号頁・発行日

vol.50, no.2, pp.97-114, 2016-06-20 (Released:2016-06-20)

参考文献数

38

被引用文献数

1

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Chemical and isotopic (δD and δ18O) compositions of 30 hot spring waters and 5 river waters in Okuhida Hot Springs, Gifu, were investigated to examine the geochemical characteristics and geothermal resources. Most hot springs were of meteoric origin and of Na+–Cl-・HCO3- and Na+–HCO3- types with low salinity (less than 30 meq/L). In the study area, meteoric water infiltrates into ground and is heated by magmatic source and enriched in Ca2+and HCO3- during interaction with underlying carbonate rocks. A part of the hot spring is enriched in CO2 due to contribution of CO2-rich volcanic fluid. The estimated underground temperatures by several geothermometers are 150 to 200℃ at the depth of ca. 1 km. The total geothermal resources in the study area are estimated to be ca. 400 MWe for producing the electricity. In the study area, most hot springs have been provided for bathing in hotels and a part of them (60℃, 3,000 L/min) has not been used. We provide this unused geothermal energy to apply for snow melting on road and room heating. For the safety use of geothermal resources in the study area, scaling problem was considered. On the basis of the saturation index of several minerals from the observed chemical compositions of hot spring waters, calcite scale is expected to be precipitated in the reservoir and in the production wells and should be considered to prohibit the precipitation.