| Project/Area Number |
15K05309
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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 |
Geology
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| Research Institution | Niigata University |
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Principal Investigator |
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| Research Collaborator |
ADACHI Yoshiko
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| Project Period (FY) |
2015-04-01 – 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 2017: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2016: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2015: ¥1,950,000 (Direct Cost: ¥1,500,000、Indirect Cost: ¥450,000)
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| Keywords | 熱水循環 / 海洋地殻 / 海嶺 / オフィオライト / 緑泥石岩 / オマーン / 熱水変質 / 銅の挙動 / オマーンオフィオライト / 熱水変質作用 |
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| Outline of Final Research Achievements |
10 chloritites bodies were found from the northern Oman ophiolite. The chloritites of the deeper level are composed of Fe-rich chlorite, while the chloritites of the shallower level are accompanied with abundant quartz veins. At the deeper horizon, Si, Ca, and alkali elements are seriously removed from the chloritite, and a huge amount of Fe is added to the chloritites. While, Si is added due to the precipitation of quartz veins at the shallower horizon, possibly owing to the lowering of temperature in the hydrothermal system. It is noted that the Cu contents of the deeply situated bodies are completely depleted as well as surrounding host rocks. However, the Cu contents of the shallower chloritites sometimes show an abnormal high concentration. Therefore, the chloritite bodies may be a root of the Cu-sulfide deposits.
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| Academic Significance and Societal Importance of the Research Achievements |
海嶺下における熱水循環は海水と玄武岩質岩石との物質循環を考える上で重要である．本研究は高速拡大海嶺で形成されたオマーンオフィオライトを対象として，海嶺下における熱水循環について検討した．斑れい岩層上部から枕状溶岩にわたる10箇所から緑泥石岩体が発見された．これらの岩石や母岩の化学分析から，海嶺下の熱水循環ではシリカや鉄，アルカリ元素などの著しい変化を伴うこと，さらに深部では銅が溶脱するが浅部ではシリカの沈殿に伴って濃集することが明らかとなった．こうした結果は海嶺付近における銅鉱床の成因論に大きく寄与する．
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