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- 大沢 信二
- 京都大学大学院理学研究科
書誌事項
- タイトル別名
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- A Hydro-geochemical Study on Hydrothermal System and Formation Processes of Hot Springs in Unzen Graben of the Shimabara Peninsula, Kyushu, Japan
- リュウタイ チキュウ カガクテキ ニ ミタ ウンゼン チコウ ノ ネッスイケイ ト オンセン ノ セイセイ カテイ
この論文をさがす
説明
In this study, a model for hydrothermal system and formation processes of hot springs (Obama, Unzen and Shimabara hot springs) in Unzen Graben of the Shimabara Peninsula was constructed on the basis of a detailed analysis of hydro-geochemical data obtained by Ohsawa et al. (2002) and NEDO (1988). Both Obama and Unzen hot springs at the western part of the graben, which are located at the southwest side of the volcanic center of Unzen Volcano, are generated by one active liquid-dominant hydrothermal fluid of Na-Cl type. Fumarolic area adjoining Unzen hot spring being on the uplands is developed by a steam separated from the hydrothermal fluid at some 300°C, and hot water of H-SO4 type of Unzen hot spring is formed by mixing of the secondary steam into shallow groundwater at about 150°C. Heat and material source of the liquid-dominant hydrothermal fluid is a high-pressure magma-derived hydrothermal fluid in which chloride is contained in Na-form. The “residual” deep thermal water migrates laterally toward the western coast while conductively cooled, and finally the mixing of seawater into the thermal water results in the formation of boiling or hot water of Obama hot spring at approximately 200°C. Warm water of HCO3 type of Shimabara hot spring at the eastern part of the graben, which is located at the east side of the volcanic center of Unzen Volcano, is formed at less than loot by mixing of a low-temperature magma-derived C02-dominant gas into shallow groundwater of meteoric origin: This low-temperature gas might be derived from a solidified magma relevant to a monogenetic volcano, Mt. Mayu-yama formed 3000 years before present, but the formation mechanism of such gas is still unaccounted for. This hydro-geochemical study cannot pinpoint the precise location of the primary magma chamber of Unzen Vocalno which is still hotly argued, however the conclusion of this study for the aspect of geochemical formation mechanism of hot spring waters agrees to the previous model (Ohta, 1973; 1975) on the whole.
収録刊行物
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- 日本地熱学会誌
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日本地熱学会誌 28 (4), 361-371, 2006
日本地熱学会
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詳細情報 詳細情報について
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- CRID
- 1390001206127315712
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- NII論文ID
- 10019366324
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- NII書誌ID
- AN00333995
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- ISSN
- 18835775
- 03886735
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- HANDLE
- 2433/245233
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- NDL書誌ID
- 8569818
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- 本文言語コード
- ja
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- データソース種別
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- JaLC
- IRDB
- NDL
- CiNii Articles
- KAKEN
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- 抄録ライセンスフラグ
- 使用不可