Origin and formation environment of deep mantle diamonds and the role of fluid
Project/Area Number |
20H02009
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Research Category |
Grant-in-Aid for Scientific Research (B)
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Allocation Type | Single-year Grants |
Section | 一般 |
Review Section |
Basic Section 17040:Solid earth sciences-related
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Research Institution | Tohoku University |
Principal Investigator |
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Co-Investigator(Kenkyū-buntansha) |
M Satish‐Kumar 新潟大学, 自然科学系, 教授 (50313929)
鍵 裕之 東京大学, 大学院理学系研究科(理学部), 教授 (70233666)
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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 |
¥18,070,000 (Direct Cost: ¥13,900,000、Indirect Cost: ¥4,170,000)
Fiscal Year 2022: ¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Fiscal Year 2021: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
Fiscal Year 2020: ¥9,620,000 (Direct Cost: ¥7,400,000、Indirect Cost: ¥2,220,000)
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Keywords | ダイヤモンド / C-H-O流体 / マグネサイト / 炭素同位体 / 高圧実験 / NanoSIMS / マントル / 深部流体 / 炭酸塩 / 包有物 / 電子顕微鏡 |
Outline of Research at the Start |
本研究は,マントル深部由来のダイヤモンド中に含まれる流体包有物に特に注目し,内部を充填する析出物の鉱物・化学組成と量比を調べ,ダイヤ生成流体の化学的特徴を明らかにする.また,ダイヤモンドの炭素同位体組成や微量元素パターンも考慮に入れ,多角的見地より深部由来ダイヤの起源と生成環境を探る.さらに,還元的なC-H-O流体と地殻・マントル物質の共存系で高圧実験を通して固液間相互作用とダイヤ生成における流体の役割を明らかにする.
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Outline of Final Research Achievements |
Analysis of nano-scale inclusions in natural samples indicates that the formation of “deep diamonds” is most likely to occur in a fluid-saturated environment. High-pressure experiments in the presence of carbonate and a CH4-rich C-H-O fluid revealed that the diamonds produced by the reaction between them have a very wide range of carbon isotopic compositions, suggesting that similar carbon isotopic compositions (-25 to -15‰) found in some E-type diamonds and deep diamonds are likely the result of carbon isotope assimilation through the reaction of subducted carbonate and reduced C-H-O fluids derived from biogenic materials. Mixing of the CO2 fluid produced by carbonate decomposition with the surrounding CH4-rich reducing C-H-O fluid may be the key to the formation of “deep diamonds”.
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Academic Significance and Societal Importance of the Research Achievements |
本研究の結果,起源・成因のよく分かっていないマントル深部起源のダイヤモンドの形成にCH4やH2Oなどの混合からなるC-H-O流体が密接に関与し,そのような流体と沈み込み帯から地球深部へ供給される炭酸塩との反応が深部起源ダイヤの起源となり得ることが初めて明確に示された.ダイヤモンドは,地球の深部に渡る炭素の大循環の主役であり,その成因を理解することは,地球における物質循環とその時間的変動・進化を捉える上でも意義は大きい.
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Report
(4 results)
Research Products
(14 results)
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[Journal Article] Formation of polycrystalline graphite aggregates in high-pressure metamorphic rocks from the Kokchetav Massif, Northern Kazkhstan2021
Author(s)
Mikailenko, D.S., Korsakov, A.V., Ohfuji, H., Rezvukhina, O.V., Pekov, I.V.
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Journal Title
Doklady Earth Sciences
Volume: 497
Issue: 1
Pages: 227-231
DOI
Related Report
Peer Reviewed / Int'l Joint Research
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[Journal Article] Plastic deformation and strengthening mechanisms of nanopolycrystalline diamond2021
Author(s)
Wang, Y., Shi, F., Gasc, J., Ohfuji, H., Wen B., Yu, T., Officer T., Nishiyama, N., Shinmei, T., Irifune, T., Dung, M.
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Journal Title
ACS Nano
Volume: 15
Issue: 5
Pages: 8283-8294
DOI
Related Report
Peer Reviewed / Open Access / Int'l Joint Research
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[Presentation] Carbon isotopic analysis of microcrystalline diamond samples recovered from MA experiments by NanoSIMS2023
Author(s)
Kawamura, H., Takahata, N., Ishida, A., Sasaki, K., Shirai, K., Ohfuji, H., Suzuki, A.
Organizer
5th International Seminar on High-Pressure Mineralogy
Related Report
Int'l Joint Research
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