| Project/Area Number |
16K05601
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Economic geology
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| Research Institution | Akita University |
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Principal Investigator |
Sugawara Toru 秋田大学, 理工学研究科, 准教授 (40420492)
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| Research Collaborator |
Ohira Toshiaki
Shimizu Chisaki
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥4,550,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥1,050,000)
Fiscal Year 2018: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Fiscal Year 2016: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
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| Keywords | カンラン石 / 玄武岩質マグマ / 秋田駒ケ岳 / 元素分配 / マグマ / ソレアイト玄武岩 / 斜長石 / 含水量 / ソレアイト / 玄武岩 / 熱力学 |
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| Outline of Final Research Achievements |
This study carried out the geohygrometer using a CaO partitioning between olivine-melt and its application to the subduction zone magma. The CaO contents of olivine crystalized in phase equilibrium experiments measured by EPMA were compared with those by LA-ICP-MS in order to investigate overestimates of CaO by a secondary fluorescence effect in EPMA. It was found that the contribution of the secondary fluorescence effect is less than 0.1 wt%, if the CaO content of matrix glass is less than 8 wt%, suggesting that CaO content measured by EPMA can be used for consideration of element partitioning. Based on literature data, modified formulation of Olivine-melt geohygrometer was developed. Environments of tholeiite basaltic magma of Akita-Komagatake volcano and Iwate volcano, Northeast Japan, are estimated by combining Olivine-melt geohygrometer, Plagiocalse-melt thermometer and Olivine-liquidus thermometer.
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| Academic Significance and Societal Importance of the Research Achievements |
マグマに対する水の溶解度は圧力が低下するほど減少するため，噴火したマグマの含水量を知ることができれば噴火直前のマグマ溜まりの深さを予測することができ，活火山の状態を知ることに役立つ．本研究は玄武岩に斑晶鉱物として含まれるカンラン石のCaO量を用いてマグマの含水量を予測する方法を提案した．また，このモデルを東北地方における玄武岩主体の代表的な火山である秋田駒ケ岳火山と岩手火山に適用した．秋田駒ケ岳のマグマ溜まりは岩手と比較して相対的に深度が浅く，温度が低温でやや還元的な環境であると考えられる．
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