2006 Fiscal Year Final Research Report Summary
Deformation mechanism of rocks due to intense strain rate in shear zone
| Project/Area Number |
16340151
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 | Shizuoka University |
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Principal Investigator |
MICHIBAYASHI Katsuyoshi Shizuoka University, Faculty of Science, Associate Professor, 理学部, 助教授 (20270978)
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| Co-Investigator(Kenkyū-buntansha) |
LIN Aiming Shizuoka University, Graduate School of Science and Technology, Professor, 創造科学技術大学院, 教授 (90283861)
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| Project Period (FY) |
2004 – 2006
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| Keywords | EBSD / peridotite / rheology / 地震 |
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| Research Abstract |
We planned to investigate ultramylonite, which is very-fine grained fault rocks in ductile shear zones, using simultaneous EDS and EBSD in order to determine the phase distribution and the dominant deformation mechanisms. The sample had been analysed previously using both EBSD and light microscopy, but resolution limitations prevented a detailed analysis of the finer grained zones. It was suspected that diffusion creep (atomic migration along grain boundaries) was the dominant mechanism in these zones-this analysis using a FEG-SEM could verify this hypothesis. During this Scientific Research, we established a SEM-EBSD system in Shizuoka University. Although our analyses on ultramylonites are still in progress, we could get some important results on peridotite study.
Seismic anisotropy in the uppermost mantle, back-arc region of the northeast Japan arc : Petrophysical analyses of Ichinomegata peridotite xenoliths
A dense network of seismic stations has been deployed across the northeast Japan arc to investigate mantle wedge structures. To attain independent petrophysical constraints, we determined the seismic properties of Ichinomegata mantle xenoliths from the back-arc region that were brought to the surface from the mantle lithosphere by volcanic eruptions. We calculated the seismic properties of the xenoliths from olivine and pyroxene crystal-preferred orientations and single crystal elastic constants. The small magnitude of measured S-wave splitting (delay time of 0.22 s in the area where the xenoliths were entrained) can be explained by the average seismic properties of mantle xenoliths for an approximately 20-km thick horizontal anisotropic layer, indicating that the mantle lithosphere could be one of the dominant sources of seismic anisotropy; this layer is possibly related to deformation in the uppermost mantle lithosphere due to back-arc spreading along the northeast Japan arc.
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Research Products
(11 results)
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[Journal Article] Seismic anisotropy in the uppermost mantle, back-arc region of the northeast Japan arc : petrophysical analyses of Ichinomegata peridotite xenoliths.2006
Author(s)
Michibayashi, K., Abe, N., Okamoto, A., Satsukawa, T., Michikura, K.
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Journal Title
Geophysical Research Letters 33
Pages: L10312
Description
「研究成果報告書概要(和文)」より
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[Journal Article] 2006. Seismic anisotropy in the uppermost mantle, back-arc region of the northeast Japan arc : petrophysical analyses of Ichinomegata peridotite xenoliths.
Author(s)
Michibayashi, K., Abe, N., Okamoto, A., Satsukawa, T., Michikura, K.
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Journal Title
Geophysical Research Letters 33
Pages: L10312 doi:10.1029/2006GL025812.
Description
「研究成果報告書概要(欧文)」より
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