| Project/Area Number |
14540421
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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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 |
TAKAZAWA Eiichi NIIGATA UNIVERSITY, Faculty of Science, Associate Professor, 理学部, 助教授 (80222082)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 2003: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2002: ¥3,600,000 (Direct Cost: ¥3,600,000)
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| Keywords | upper mantle / peridotite / trace elements / asthenosohere / lithosphere / Oman ophiolite / Horoman / mantle-melt reaction / 上越帯 / かんらん岩 / オマーン / オフィオライト |
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| Research Abstract |
This research investigated the mantle-melt reaction that occurs at Earth's extensional environments such as continental rift and mid-ocean ridge. The studied fields includes the Horoman peridotite complex in the Hidaka Metamorphic Belt, Hokkaido, Japan and the mantle section of the Oman ophiolite. On the basis of spatial variation of trace elements such as rare earth elements in the mantle peridotites and in their constituent minerals the reaction between lithospheric mantle and ascending asthenospheric melt was quantitatively modeled. The study showed that the Horoman peridotite are highly heterogeneous in a meter scale so that even in the 140 meters section fertile Iherzolite with primitive mantle composition and depleted harzburgite are observed. The variation of incompatible elements are further complicated thereby showing the metasomatism by asthenospheric melt flow. On the other hand, the mantle section of the Oman ophiolite are more homogeneous in the scale of ten kilo meters. Abundances of major and trace element in the area of 25 x 15km^2 in the Oman mantle section are less variable than those in the 140m section of the Horoman peridotite. Compositional variations in the mantle section of the Oman ophiolite are mainly explained by partial melting and melt extraction beneath mid-ocean ridge. However, this research found greater variations in the Oman ophiolite than it has been known before. These heterogeneities may have formed by remelting and refertilization of oceanic lithospheric mantle in a scale of km.
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