The origin and isotopic compositions of primitive organic matter inferred from microanalysis on carbonate in meteorites
| Project/Area Number |
16K17838
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Geochemistry/Cosmochemistry
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| Research Institution | Ibaraki University |
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Principal Investigator |
Fujiya Wataru 茨城大学, 理工学研究科(理学野), 准教授 (20755615)
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| Project Period (FY) |
2016-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2016: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | 炭素質コンドライト / 炭酸塩鉱物 / 酸素同位体比 / 炭素同位体比 / 始原的隕石 / 水質変成作用 / マンガン・クロム年代測定 / 隕石 / 炭酸塩 / 有機物 / 水質変成 |
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| Outline of Final Research Achievements |
I measured oxygen and carbon isotopic compositions of carbonate minerals in primitive meteorites (chondrites).By using secondary ion mass spectrometry, we investigated heterogeneity of isotopic compositions within individual carbonate grains with a spatial resolution of a few micrometers. We found that oxygen isotopic compositions are highly variable within carbonate grains, whereas carbonate isotopic compositions are almost constant. We concluded that oxygen isotopic compositions are determined by water-rock interactions (aqueous alteration) during precipitation of carbonate minerals from aqueous fluids, while carbon isotopic compositions reflect mixing ratios of organic matter and carbon dioxide ice accreted to meteorite parent bodies.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究では、微小領域の同位体比を測定する手法を駆使して、炭酸塩粒子内では炭素同位体比の変動は小さいが、粒子間の変動は大きいことを見出した。これは溶存炭素の炭素同位体比が空間的に不均質であったが、炭酸塩鉱物の形成中には変化しなかったことを示している。その空間的不均質は、炭素-13に富む成分と乏しい成分という、同位体比の異なる二つの成分が隕石の母天体中で不完全に混合していたことを示唆する。炭素-13に富む成分は隕石母天体に集積した固体二酸化炭素である可能性が高い。本研究は、隕石の母天体に含まれる固体二酸化炭素の存在量を推定することで、母天体が形成した当時の温度環境を制約できる可能性を切り拓いた。
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Report
(5 results)
Research Products
(24 results)
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[Journal Article] Migration of D-type asteroids from the outer solar system inferred from carbonate in meteorites.2019
Author(s)
Fujiya, W., Hoppe, P., Ushikubo, T., Fukuda, K., Lindgren, P., Lee, M. R., Koike, M., Shirai, K., and Sano, Y.
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Journal Title
Nature Astronomy
Volume: 3
Issue: 10
Pages: 910-915
DOI
Related Report
Peer Reviewed / Int'l Joint Research
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