2022 Fiscal Year Final Research Report
Microbial ecosystem involved in the genesis of banded iron formation at ca. 3.2 Ga
Project/Area Number |
19K15486
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Research Category |
Grant-in-Aid for Early-Career Scientists
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Allocation Type | Multi-year Fund |
Review Section |
Basic Section 31020:Earth resource engineering, Energy sciences-related
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Research Institution | Hokkaido University |
Principal Investigator |
Ohtomo Yoko 北海道大学, 工学研究院, 助教 (80612902)
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Project Period (FY) |
2019-04-01 – 2023-03-31
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Keywords | Banded Iron Formation / Great Oxidation Event / Cyanobacteria / Iron-oxidizing Bacteria / Graphene |
Outline of Final Research Achievements |
Microorganisms involved in the iron oxidation of Banded Iron Formation before ca. 2.4 Ga Great Oxidation Event (GOE) has been actively discussed in Early Earth Science. The objective of this study is to give constraints on the microbial species by micro to nano morphological/structural observations, micro-spectrometry, carbon and nitrogen stable isotope analyses of carbonaceous materials in the 3.2 Ga BIF, Moodies Group, Barberton Greenstone Belt, South Africa with petrological data. Morphological observations of carbonaceous materials extracted by micro-sampling and acid-treatment suggest that multiple microbial species flourished before the GOE and each microbial community fluctuated with the transition of the iron oxidation conditions of the BIF. The interiors of the carbonaceous materials are not like microfossil-like structures but showed aggregates of micro-grains covered by thin films, containing graphene structures.
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Free Research Field |
地球化学, 地質学, 岩石鉱物学
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Academic Significance and Societal Importance of the Research Achievements |
一般に太古代炭素質物質は変質を受けており、形態から起源を同定することは難しい。本研究では炭素質物質の形態観察と岩石タイプの相関から、微生物種の変動を示唆する情報を得ることに成功した。また本研究の炭素質物質はグラフェン構造を含んでいた。グラフェンは工業的には化学気相成長か全合成により生成されており、天然の岩石からの発見例はない。本研究の炭素質物質の変成温度は300度程度で既存の工業的生成条件とは異なる。続成・変成の過程で特殊な有機分子溶存流体からグラフェンが生成するという現象は太古代特有の地球表層炭素循環を理解する手がかりとなるほか、工業的なグラフェン製造法に示唆を与える可能性がある。
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