Project/Area Number |
09440182
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Research Category |
Grant-in-Aid for Scientific Research (B)
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Allocation Type | Single-year Grants |
Section | 一般 |
Research Field |
Petrology/Mineralogy/Science of ore deposit
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Research Institution | The University of Tokyo |
Principal Investigator |
KANEOKA Yutaka Earthquake Research Institute, University of Tokyo, Professor, 地震研究所, 教授 (30011745)
|
Co-Investigator(Kenkyū-buntansha) |
MIURA Yayoi Earthquake Research Institute, University of Tokyo, Research Associate, 地震研究所, 助手 (90282730)
TAKIGAMI Yutaka Faculty of Law, Kanto-Gakuen University, Associate Professor, 法学部, 教授 (40206909)
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Project Period (FY) |
1997 – 1999
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Keywords | mantle / noble gas isotopic ratio / volatile elements / evolution of the Earth / recycling of materials / crustal fluid / ィイD13ィエD1He / ィイD14ィエD1He / island arc |
Research Abstract |
In this study, we measured noble gas and Be isotopes in mantle materials and basalt-ic rooks to reveal the states of noble gas and volatile elements and recycling of mate-rials in the mantle and have obtained the following results. We extracted noble gases from olivine separates of lherzolites carried in siberian alkaline basalts (10-40Ma) by crushing and stepwise heating methods. Among them, we have found samples which have the ィイD13ィエD1He/ィイD14ィエD1He lower than the atmospheric value. This implies the possibility of the effect of crustal fluids in the subcontinental mantle. Pillow glasses of MORB from around the Rodrigues Triple Junction. Indian Ocean, show the different ィイD140ィエD1Ar/ィイD136ィエD1Ar depending on the segment. This may mean that the thermal water might have affected to homogenize the ratio over the length of a few tens of km. We measured the ィイD101ィエD1Be/ィイD19ィエD1Be in Quaternary volcanic rocks from the Hokkaido-Northeast Japan with Tandem accelerated mass spectrometer. The results indicate that the ratio are systematically higher than those of non island arc area and suggests the incorporation of oceanic sediments in the island arc magma. Based on the Ar isotopic ratio of the phlogopite in the Horoman perodotite, we have revealed the effect of sea- or ground water for the formation of phlogopite. Through such studies, we have clarified the effect of crustal materials and grtound water to mantle materials in various ways and demonstrate the importance of recycling materials for the evolution of the Earth.
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