| Project/Area Number |
17K05713
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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 |
Petrology/Mineralogy/Economic geology
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| Research Institution | Teikyo University of Science & Technology |
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Principal Investigator |
MATSUKAGE Kyoko N. 帝京科学大学, 総合教育センター/自然環境学科, 教授 (80343078)
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| Project Period (FY) |
2017-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2019: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
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| Keywords | 水 / 鉄チタン水酸化物 / 地球内部 / 海洋プレート / 高圧含水相 / 沈み込み帯 / マントル / 高温高圧実験 |
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| Outline of Final Research Achievements |
We experimentally discovered new hydrous phases, FeTi oxyhydroxides (FeOOH-TiO2). To determine the phase relation of these phases in subducting basaltic system, we performed experiments of basalt + H2O system by using multi-anvil apparatus at 10-23 GPa and 750-1200°C. We found that the phase with α-PbO2 type crystal structure was stable at wide pressure range at deep upper mantle and mantle transition zone at slab temperatures. In this system, lawsonite is a major hydrous mineral in the upper mantle, although it dehydrates at ~10 GPa. Our study indicates that the FeTi oxyhydroxide represents the main carrier of water at depths beneath the lawsonite stability field. After dehydration of FeTi oxyhydroxide at ~19 GPa, CaTi perovskite was formed as a Ti-bearing phase, and Al-bearing phase D was stable as a hydrous phase. Our findings suggest that water transport in the Earth’s deep interior by basaltic crust is probably much more efficient than had been previously thought.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究の結論として、鉄チタン水酸化物が地球の深さ300～600kmで安定に存在しうること、この領域での主要な水成分の運び手及びリザバーであること、が示された。海洋地殻物質は元来我々研究者が考えていたよりも、効率的に水成分を地球深部に運搬・保持し、地球内部の化学進化過程に影響を与えていると考えられる。
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