2014 Fiscal Year Final Research Report
Metasomatism and transitional-elements concentration process by fluids in the mantle wedge
| Project/Area Number |
24540518
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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/Science of ore deposit
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| Research Institution | Kumamoto University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
ARAI Shoji 金沢大学, 自然システム学系, 特任教授 (20107684)
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| Project Period (FY) |
2012-04-01 – 2015-03-31
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| Keywords | マントルウェッジ / 交代作用 / 地球化学 / 岩石学 |
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| Outline of Final Research Achievements |
We examined two mantle-derived peridotites to clarify modification processes by melts or slab-derived fluids: the one is sub-arc mantle xenoliths from the volcanic front and the other is solid intrusive peridotite blocks or basal peridotites of ophiolite above their metamorphic sole.
All peridotite xenoliths, we examined, contain H2O fluid inclusions with or without CO2, and the presence of H2O fluids is quite normal beneath the sub frontal arc mantle although there have been quite rare from other mantle xenoliths even from arc setting. Some H2O fluid contain high (up to 17 wt%) amount of NaCl eq. content. Such high-NaCl aqueous fluid is quite important for metasomatism due to high solubility of LIL and transitional elements in it.
We also found fluid-related metasomatism in ophiolite, formed at arc setting. The H2O fluid was enriched in Si and Al, and transport Cr with some anions. Chlorine ion and/or other anions are quite important for the transportation of transitional metals.
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| Free Research Field |
マントル岩石学
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