| Project/Area Number |
13640416
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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 |
固体地球物理学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
OGAWA Masaki The University of Tokyo, Graduate School of Arts and Science, Associate Professor, 大学院・総合文化研究科, 助教授 (30194450)
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| Project Period (FY) |
2001 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2003: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2002: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2001: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | mantle connection / plate tectonics / magmatism / mantle evolution / numerical simulation / プレート運動 |
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| Research Abstract |
The earlier numerical model of coupled magmatism-mantle convection system has been extended by including moving plates and the extended model of the coupled system (or mantle GCM) has been applied to the problem of mantle evolution. The numerical model suggests that the earth's mantle has evolved in two stages. On the earlier stage when the mantle is strongly heated by radioactive elements, the lower mantle are hot enough to frequently induce mantle overturn and the resulting plume activity. The magmatism induced by the plume activity makes plate motion and ridge volcanism strongly time-dependent. As the internal heating by radioactive elements becomes weaker than a threshold (the second stage), however, the mantle overturn suddenly stops and mantle convection and ridge volcanism becomes more steady. The ridge volcanism and hot spot volcanism induced by mantle overturn make the mantle chemically stratified with the deeper part of lower mantle occupied by magmatic products and the uppermost mantle occupied by residue of magma throughout the earth's history in spite of the whole mantle convection induced by subducting slabs that penetrate deep into the lower mantle. The thermal and chemical state of the numerically modeled mantle well captures the overall features of the present earth's mantle revealed by recent geochemical and seismological observation. The transition from the first to the second stage may corresponds to the Archean-Proterozoic boundary of the earth's history.
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