| Project/Area Number |
20K04126
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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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| Review Section |
Basic Section 17040:Solid earth sciences-related
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
HOUSER Christine 東京工業大学, 地球生命研究所, 特任助教 (20723737)
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| Co-Investigator(Kenkyū-buntansha) |
土屋 旬 愛媛大学, 地球深部ダイナミクス研究センター, 准教授 (00527608)
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2022: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2021: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2020: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
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| Keywords | Mantle transition zone / hydrous minerals / global seismology / Earth composition / plate tectonics / mineral physics / mantle transition zone / molecular dynamics |
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| Outline of Research at the Start |
PI Houser will perform 3D mapping of seismic velocity variations and seismic wave reflections to create a new seismic model of the Earth's mantle transition zone. Co-I Tsuchiya will use advanced molecular dynamics calculations to determine the seismic properties of water-bearing minerals at the high pressures and temperatures. The seismic observations will be compared to calculated rock properties to determine the location and concentration of water in the mantle. We will combine the latest seismology and mineral physics to put realistic bounds on Earth's interior water storage.
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| Outline of Final Research Achievements |
The mantle transition zone is the layer separating the Earth's upper and lower mantle. The unique mantle transition zone minerals have the largest water storage capacity in the mantle such that mapping water in this region is critical to understanding the Earth's total water budget. PI Houser measures and interprets seismic reflections, and Co-I Tsuchiya develops ab initio molecular dynamics to examine the stability of dense hydrous magnesium silicates in Earth's deep mantle. We find hydrogen leaking into mantle during subduction would be stored in the rare hydrous mineral phases, leaving the overall mantle generally dry. We observe water as small local patches rather than a layer saturated to the maximum capacity. Additional work shows that nitrogen in today's mantle originated from early subducted sediments rather than a magma ocean. Our results support the ingassing through subduction rather than outgassing from a magma ocean of volatile elements from Earth's mantle.
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| Academic Significance and Societal Importance of the Research Achievements |
This project sets limits on Earth's deep water storage to understand how the Earth trapped water during formation and maintains the water cycle. We find interior water present in small regions while most water returns to the surface allowing life to emerge and sustain itself over billions of years.
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