2006 Fiscal Year Final Research Report Summary
Experimental Studies on the interaction between crustal deformation and geo-fluids
| Project/Area Number |
16340150
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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 | The University of Tokyo |
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Principal Investigator |
SHIMIZU Ichiko The University of Tokyo, Graduate School of Science, Assistan Professor, 大学院理学系研究科, 助手 (40211966)
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| Co-Investigator(Kenkyū-buntansha) |
MICHIBAYASHI Katsuyoshi Shizuoka University, Faculty of Science, Associate Professor, 理学部, 助教授 (20270978)
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| Project Period (FY) |
2004 – 2006
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| Keywords | High-PT deformation experiments / solid-medium aparatus / agate / serpentinite / differential stress / fluid / dehydration reaction / brittle-ductile transition |
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| Research Abstract |
Rheological properties of crustal rocks are significantly affected by H2O fluids in the pore spaces, thin water films in the grain boundaries, and a small amount of water that dissolved in crystals. In order to investigate the effects of water on crustal deformation, we set up a solid-medium deformation apparatus (MK65S), installed at the the Shizuoka University, and established experimental techniques to obtain high-resolution mechanical data at high-pressure and high-temperature conditions up to 1GPa and 1000 degrees. Constant strain-rate experiments were conducted by used cylindrical samples of agates and serpentinites (mainly composed of antigolite). Both samples release free water at elevated temperatures. Agate samples recrystallized into quartz aggregates and exhibit steady-state creep behaviors. The c-axis fabrics of recrystallized quartz concentrate to the compression axis, suggesting the effects of strain energy-driven grain boundary migration. The change of water contents in the sample before and after high PT experiments was measured by a FTIR microscopy. Deformation experiments of serpentinite were performed at 800MPa confining pressure at 500 C and 700 C, below and over the temperature of dehydration reaction, respectively. The samples were jacketed by Ag tubes and disks. Some samples were pre-heated at 700C or 750C for 0.5-1 hours under static conditions. At high-temperature runs (700C), serpentinite shows drastic weakening and creep behaviors, whereas it does not yield at the low-temperature run (500C), even when differential stress reaches to 1GPa. Formation and collapse of pores associated with dehydration reaction may be responsible to the britte-ductile transition of serpentinites. It is suggested that dehydration of serpentinites plays important roles in triggering intra-slab earthquakes in the double seismic zones.
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Research Products
(10 results)
