2016 Fiscal Year Final Research Report
The constraints from U-Th radioactive disequilibrium on genetic processes of volcanoes in the Kyshu arc
| Project/Area Number |
26400523
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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 |
Geochemistry/Cosmochemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
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| Project Period (FY) |
2014-04-01 – 2017-03-31
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| Keywords | 九州弧 / ウラン－トリウム放射非平衡 / 火山岩 / スラブ溶融 / 堆積物溶融 / 沈み込み流体 |
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| Outline of Final Research Achievements |
We examined whether the volcanisms in Kyushu island are related to the addition of slab derived fluids or the melting of slab or sediments with the index of radioactive disequilibrium between 230Th and 238U. Forty five samples from Yufudake, Kuju, Oninomi, Aso, Kirishima, Kaimon, Unzendake and Fukue-jima were analyzed.
The results of the analyses indicated most of the samples have (230Th/238U) of close to unity. Samples of Oninomi, a part of Aso, Unzendake, Fukue-jima and a part of Kaimon have (230Th/238U) larger than 1.05, suggesting melting under the presence of residual garnet. The results also indicated the absence of (230Th/238U) less than 1.0, which is commonly observed among the volcanic rocks originated by the volcanisms triggered by the addition of slab derived fluids.
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| Free Research Field |
地球化学
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