| Project/Area Number |
09304051
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| Research Category |
Grant-in-Aid for Scientific Research (A).
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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 | Tohoku University |
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Principal Investigator |
OKTANI Eiji Tohoku University, Inst, Min, Petrol. Econ. Geol., Professor, 大学院・理学研究科, 教授 (60136306)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Akio Tohoku University, Inst. Min. Petrol. Econ. Geology, Res.Assoc, 大学院・理学研究科, 助手 (20281975)
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| Project Period (FY) |
1997 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥33,100,000 (Direct Cost: ¥33,100,000)
Fiscal Year 2000: ¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 1999: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1998: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1997: ¥24,800,000 (Direct Cost: ¥24,800,000)
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| Keywords | phase transition / transition zone / lower mantle / kinetics / magma / hydrous phase / care formation / high pressure / スーパーハイドラスB相 / EGG相 / δ-ALOOH相 / CaCl_2構造 / 水 / 含水G相 / δ相 / CaCl_2型構造 / AlOOH / 元素分配 / 高温高圧X線その場観察実験 / α-β相転移 / 分解反応 / 焼結体ダイヤモンド / 融解温度 / コマチアイト / クラトニックペリドタイト / 初期地球 |
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| Research Abstract |
In this research, we clarified the phase transitions and partitioning of elements in mantle minerals in the transition zone and the lower mantle, i.e., stability of hydrous phases, melting and physical properties of magma, phase transition kinetics, core formation process in the early Earth. One of the important results in this study is on the stability of hydrous phases. We observed two new hydrous minerals which are expected to exist in the lower mantle ; i.e., phase G (Mg1.14Si1.73H2.81O6) and phase d-AlOOH.Phase G is stable at relatively low temperature around 1000-1200℃ at around 25 GPa and it is expected to exist in the peridotite layer in the cold slab descending into the lower mantle. Whereas phase delta AlOOH is stable in the sediment components in the descending slabs in the upper most part of the lower mantle. These phases work as the water carrier into the lower mantle. Another mportant results in this research is on decomposition kinetics of ringwoodite. We observed periclase and ilmenite, and priclase and stishovite as a metastable assemblage in the beginning of the decomposition of ringwoodite. These metastable assemblages eventually disappeared within 10 minutes to form stable assemblage, i.e., periclase and perovskite.
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