부곡 지열수의 심부환경과 지화학적 진화: 유황형 지열수의 생성과정 재해석 (Geochemical Evolution and Deep Environment of the Geothermal Waters in the Bugok Area: Reconsideration on the Origin of Sulfate-type Geothermal Water)

서지정보

· 발행기관 : 대한자원환경지질학회
· 수록지 정보 : 자원환경지질 / 34권 / 4호 / 329 ~ 343페이지
· 저자명 : 고용권, 윤성택, 김천수, 배대석, 박성숙

초록

The deep environment and geochemical evolution of the Bugok geothermal waters, located in the Kyeongnam Province, was re-interpreted based on the hydrochemical and isotopic data published by Yun et al. (1998). The geothermal waters of the Bugok area is geochemically divided into three groups: Geothermal water I, II and III groups.
Groups I and II are geochemically similar: high temperature (55.2 77.2o C and chemically belonging to Na-SO4 types. However, pH and Eh values are a little different each other and Group II water is highly enriched in SO4 compared to Group I water. Group III water, occurring from peripheral sites of the central part of the geothermal waters, shows temperature range of 29.3 to 47.0o C and belongs to Na-HCO3-SO4 types. The deep environment and geochemical evolution of the Bugok geothermal waters, showing the diversity of geochemistry, can be interpreted as follows: 1) Descending to great depth of meteoric waters that originated at high elevation and reacting with sediments and/or granites in depth. The SO4 concentration of the waters has been increased by the dissolution of sulfate minerals in sediments. 2) During the continuous descending, the waters has met with the reduction environment, producing the H2S gas due to sulfate reduction. The waters has been heated up to 130o C and the extent of water-rock reaction was increased. At this point, pH of waters are increased, SO4 concentration decreased and calcite precipitated, therefore, the waters show the Na-SO4 type. 3) Ascending of the geothermal waters along the flow path of fluids and mixing with less-deeply circulated waters. The SO4 concentration is re-increased due to the oxidation of H2S gas and/or sulfide minerals in sediments. During continuous ascending, these geothermal waters are mixed with shallow groundwater.

영어초록

The deep environment and geochemical evolution of the Bugok geothermal waters, located in the Kyeongnam Province, was re-interpreted based on the hydrochemical and isotopic data published by Yun et al. (1998). The geothermal waters of the Bugok area is geochemically divided into three groups: Geothermal water I, II and III groups.
Groups I and II are geochemically similar: high temperature (55.2 77.2o C and chemically belonging to Na-SO4 types. However, pH and Eh values are a little different each other and Group II water is highly enriched in SO4 compared to Group I water. Group III water, occurring from peripheral sites of the central part of the geothermal waters, shows temperature range of 29.3 to 47.0o C and belongs to Na-HCO3-SO4 types. The deep environment and geochemical evolution of the Bugok geothermal waters, showing the diversity of geochemistry, can be interpreted as follows: 1) Descending to great depth of meteoric waters that originated at high elevation and reacting with sediments and/or granites in depth. The SO4 concentration of the waters has been increased by the dissolution of sulfate minerals in sediments. 2) During the continuous descending, the waters has met with the reduction environment, producing the H2S gas due to sulfate reduction. The waters has been heated up to 130o C and the extent of water-rock reaction was increased. At this point, pH of waters are increased, SO4 concentration decreased and calcite precipitated, therefore, the waters show the Na-SO4 type. 3) Ascending of the geothermal waters along the flow path of fluids and mixing with less-deeply circulated waters. The SO4 concentration is re-increased due to the oxidation of H2S gas and/or sulfide minerals in sediments. During continuous ascending, these geothermal waters are mixed with shallow groundwater.

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