| Project/Area Number |
15340181
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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 |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | KYUSHU UNIVERSITY (2004)
Tohoku University (2003) |
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Principal Investigator |
KUBO Tomoaki Kyushu University, Fac. of Sci., Associate Professor, 大学院・理学研究院, 助教授 (40312540)
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| Co-Investigator(Kenkyū-buntansha) |
KATO Takumi Kyushu Univ., Fac. of Sci., Professor, 大学院・理学研究院, 教授 (90214379)
UEHARA Seiichiro Kyushu Univ., Fac. of Sci., Research Associate, 大学院・理学研究院, 助手 (70158773)
KONDO Tadashi Tohoku Univ., Fac. of Sci., Associate Professor, 大学院・理学研究科, 助教授 (20252223)
OHTANI Eiji Tohoku Univ., Fac. of Sci., Professor, 大学院・理学研究科, 教授 (60136306)
長瀬 敏郎 東北大学, 総合学術博物館, 助教授 (10237521)
鈴木 昭夫 東北大学, 大学院・理学研究科, 助手 (20281975)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥16,900,000 (Direct Cost: ¥16,900,000)
Fiscal Year 2004: ¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2003: ¥13,800,000 (Direct Cost: ¥13,800,000)
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| Keywords | hiah-pressure experiments / in-situ X-ray diffraction / sintered diamond multi-anvil / TEM / high-pressure transformations of mantle minerals / transformation kinetics / subducting oceanic plates / stagnant slabs / 相転移メカニズム / マントルダイナミクス |
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| Research Abstract |
We have developed techniques on high-pressure generations using sintered diamond multi-anvil systems combined with synchrotron radiation, which enables to obtain time-resolved X-ray diffraction data every 10-30 seconds up to 35 GPa and 2000K. We also tested new sintered diamond anvils manufactured by Ringwood Superabrasives for the X-ray window of multi-anvil apparatus.
Based on these techniques, we have quantitatively studied on kinetics of post garnet transformations in natural garnet, high-pressure transformations in pyroxenes (enstatite and diopside), and effects of water on the olivine-spinel transformation kinetics. Transformation microstructures and water contents of samples recovered were examined using TEM and FTIR. In addition to these studies, we have also examined about formation of metastable cubic perovskite, dehydration reaction of high-pressure hydrous minerals, and mechanisms and kinetics of high-pressure transformations in shocked meteorites, those have important implications for subduction processes. Cation diffusion kinetics in wadsleyite have been experimentally examined and rheology of subducting plates and mantle transition zone was discussed.
We have extrapolated quantitative kinetic data obtained to subduction zone conditions and construct metastable mineralogy in subducting plates. We have calculated the density of subducting slabs taking transformation kinetics into accounts, which suggests that the subducting slabs are buoyant at the top of the lower mantle due to the presence of metastable low-pressure phases. Grain-size reductions caused by non-equilibrium transformations can reduce strength of subducting plates. These are important for the formation of stagnant slabs at the top of the lower mantle.
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