ラテライト形成過程と表層環境の地球史進化：鉄・三種酸素同位体の地球化学からの視点

2014 Fiscal Year Annual Research Report

• Project/Area Number: 24654164
• Research Institution: Toho University
• Principal Investigator: 山口 耕生 東邦大学, 理学部, 准教授 (00359209)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: ラテライト / 鉄 / 酸素 / 原生代

Outline of Annual Research Achievements

約22億年前に発達したラテライト質風化断面を対象に、形成時の水の働きと大気化学の痕跡を解明することを本研究の主目標とする。そのため、鉄同位体に関する既発表論文を基盤に、ラテライト鉄酸化物の酸素同位体比を測定し、ラテライトの鉄ー酸素の安定同位体地球化学のレファレンスとなるデータセット構築を行い、ラテライト形成の定量的モデル構築を行う。これにより、地球史を通じたラテライトの形成に関する鉄と酸素の同位体地球化学の突破口を切り拓き、地球表層環境の進化に関する重要な知見を得る。
本研究は地球史初期の表層（大気ー大陸ー海洋システム）環境の進化を探る上で重要であり、研究の意義は大きい。「地球史を通じてラテライト形成過程は不変である」ことを示すことができれば、現世のラテライトの形成（特に鉄の溶脱）に必須である陸上生命活動を起源とする有機酸が、太古のラテライト形成（または一般に大陸風化）においても重要であったとの示唆が可能となる。つまり、地球史の初期における微生物生命圏の進化を探る上でも、本申請研究は深い示唆に富むものになる。
2014年度は、約22億年前のボツワナ産のラテライト試料（Yamaguchi et al., 2007; EPSL）の酸素同位体組成データの詳細な検討の結果、ラテライト質風化断面に関する鉄同位体組成対 酸素同位体組成の負相関を発見した。つまり、水ー岩石相互作用、すなわちラテライト化作用が強い部位ほど54Feが溶脱して56Feにより富み、降水の影響下で形成する２次鉱物は18Oに枯渇する、ことが言える。以上が研究実績の概要である。

Research Products

• [Journal Article] Sedimentology of the Paleoproterozoic Kungarra Formation, Turee Creek Group, Western Australia: A conformable record of the transition from early to modern Earth. (2015)
  • Author(s): Van Kranendonk, M.J., Mazumder, R., Yamaguchi, K.E., Yamada, K., and Ikehara, M.
  • Journal Title: Precambrian Research Volume: 256 Pages: 314-343
  • DOI: doi:10.1016/j.precamres.2014.09.015
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Life’s adaptation to the oxygen revolution: Litho-stratigraphic analysis of a stromatolite-thrombolite reef from the Paleoproterozoic Turee Creek Group, Western Australia (2015)
  • Author(s): Barlow, E., Van Kranendonk, M.J., Yamaguchi, K.E., Hegner, E., Yamada, K., Ikehara, M., and Lepland, A.
  • Journal Title: Geobiology Volume: 未定 Pages: 未定
  • Peer Reviewed / Acknowledgement Compliant
• [Journal Article] Determination of 129I/127I in environmental water before and after the 2011 Fukushima Daiichi nuclear power plant accident with a solid extraction disk. (2014)
  • Author(s): Bamba, S., Yamaguchi, K.E., and Amano, H.
  • Journal Title: Journal of Radioanalytical and Nuclear Chemistry Volume: 301 Pages: 75-80
  • DOI: DOI 10.1007/s10967-014-3055-8
  • Peer Reviewed / Acknowledgement Compliant
• [Presentation] Restoration environment of Archean/Proterozoic deep ocean floor: REAP project. (2015)
  • Author(s): Kiyokawa, S., Ito, T., Ikehara, M., Yamaguchi, K.E., Suganuma, Y., Horie, K., and Onoue, T.
  • Organizer: 3rd International Geoscience Symposium: Project A in Korea.
  • Place of Presentation: Daejeon, Korea
  • Year and Date: 2015-03-04 – 2015-03-08
• [Presentation] Reconstruction of 3.2 Ga sedimentary environment: Carbon and sulfur analysis for DXCL drillcores of Pilbara, Western Australia (2015)
  • Author(s): Miki, T., Kiyokawa, S., Naraoka, H., Takahata, N., Ishida, A., Ito, T., Ikehara, M., Yamaguchi, K.E. and Sano, Y.
  • Organizer: 3rd International Geoscience Symposium: Project A in Korea.
  • Place of Presentation: Daejeon, Korea
  • Year and Date: 2015-03-04 – 2015-03-08
• [Presentation] Biogeochemical cycling of Fe, S, C, N, and Mo in the 3.2 Ga ocean: Constraints from DXCL-DP black shales from Pilbara, Western Australia. (2014)
  • Author(s): Yamaguchi, K.E., Naraoka, N., Ikehara, M., Ito, T., and Kiyokawa, S.
  • Organizer: The 2014 AGU Fall Meeting
  • Place of Presentation: San Francisco, USA
  • Year and Date: 2014-12-15 – 2014-12-19
• [Presentation] Sulfur speciation and isotope analysis of the 2.7 Ga shallow- and deep-facies black shales from Pilbara, Western Australia (2014)
  • Author(s): Minami, H., Abe, A., Yamaguchi, K.E., and Naraoka, N.
  • Organizer: The 2014 AGU Fall Meeting
  • Place of Presentation: San Francisco, USA
  • Year and Date: 2014-12-15 – 2014-12-19
• [Presentation] Geochemistry of carbon and sulfur in the 2.7 Ga stromatolitic carbonate and shale (ABDP#10 core) from Meentheena, Western Australia. (2014)
  • Author(s): Tomiuka, T. and Yamaguchi, K.E.
  • Organizer: The 2014 AGU Fall Meeting
  • Place of Presentation: San Francisco, USA
  • Year and Date: 2014-12-15 – 2014-12-19
• [Presentation] Organic / inorganic carbon content and isotope analysis of 3.1Ga Cleaverville Formation in Pilbara, Australia: Result of DXCL project (2014)
  • Author(s): Miki, T., Kiyokawa, S., Ito, T., Ikehara, M., Yamaguchi, K.E.
  • Organizer: The 2014 AGU Fall Meeting
  • Place of Presentation: San Francisco, USA
  • Year and Date: 2014-12-15 – 2014-12-19
• [Presentation] 32-31 億年前の海底堆積層解析：DXCL掘削からみられる海洋環境と縞状鉄鉱層形成 (2014)
  • Author(s): 清川 昌一、伊藤 孝、池原 実、山口 耕生、尾上 哲治、菅沼 悠介、堀江 憲治、奈良岡 浩、三木 翼
  • Organizer: 日本地質学会第121年学術大会
  • Place of Presentation: 鹿児島大学郡元キャンパス（鹿児島県鹿児島市）
  • Year and Date: 2014-09-13 – 2014-09-15
• [Presentation] Mesoarchean oceanic floor environment at sedimentary sequences in Dixon Island-Cleaverville Formation formations, Pilbara Australia: Result of DXCL drilling project. (2014)
  • Author(s): Kiyokawa, S., Ito, T., Ikehara, M., Yamaguchi, K.E., Naraoka, H., Onoue, T., Horie, K., Aihara, Y., Miki, T.
  • Organizer: 21st General Meeting of the International Mineralogical Association
  • Place of Presentation: Sandton City, South Africa
  • Year and Date: 2014-09-01 – 2014-09-05
• [Presentation] Reconstruction of 3.2Ga sea floor environment: In situ and whole-rock analysis of carbon and sulfur isotope of DXCL project. (2014)
  • Author(s): Miki, T., Kiyokawa, S., Naraoka, H., Takahata, N., Ishida, A., Ito, T., Ikehara, M., Yamaguchi, K.E., Sakamoto, R., and Sano, Y.
  • Organizer: 21st General Meeting of the International Mineralogical Association
  • Place of Presentation: Sandton City, South Africa
  • Year and Date: 2014-09-01 – 2014-09-05
• [Presentation] Oxidative biogeochemical cycling of Fe, S, C, N, and Mo in the 3.2 Ga ocean: Constraints from DXCL-DP sulfidic black shales from northwestern Pilbara, Western Australia. (2014)
  • Author(s): Yamaguchi, K.E., Kobayashi, Y. Shiina, A., Yamada, K., Kobayashi, D., Nakamura, T., Sakamoto, R., Naraoka, H., Ikehara, M., Ito, T., and Kiyokawa, S.
  • Organizer: Origins 2014
  • Place of Presentation: 奈良県新公会堂（奈良県奈良市）
  • Year and Date: 2014-07-06 – 2014-07-11
• [Presentation] Sulfur speciation and isotope analysis ofin the 2.7 Ga shallow- and deep-facies black shales from Pilbara, Western Australia (2014)
  • Author(s): Minami, H., Abe, A., Yamaguchi, K.E., Naraoka, H.
  • Organizer: Origins 2014
  • Place of Presentation: 奈良県新公会堂（奈良県奈良市）
  • Year and Date: 2014-07-06 – 2014-07-11
• [Presentation] Origin of organic matter in 3.2 Ga black shales revealed by infrared and laser Raman microspectroscopy (2014)
  • Author(s): Nakamura, T,, Yamaguchi, K.E. Ikehara, M., Kiyokawa, S., and Ito, T.
  • Organizer: Origins 2014
  • Place of Presentation: 奈良県新公会堂（奈良県奈良市）
  • Year and Date: 2014-07-06 – 2014-07-11
• [Presentation] Geochemistry of C, O and S in the 2.7 Ga stromatolite (ABDP#10 core) from Meenthena, Western Australia (2014)
  • Author(s): Tomiuka, T., Yamaguchi, K.E., Sakai, S.
  • Organizer: Origins 2014
  • Place of Presentation: 奈良県新公会堂（奈良県奈良市）
  • Year and Date: 2014-07-06 – 2014-07-11
• [Presentation] Denitrification in the Mesoarchean deep ocean: Evidence from nitrogen isotope compositions of kerogen in black shales from Pilbara, Western Australia. (2014)
  • Author(s): Kotani, M., Yamaguchi, K.E., and Ikehara, M.
  • Organizer: Origins 2014
  • Place of Presentation: 奈良県新公会堂（奈良県奈良市）
  • Year and Date: 2014-07-06 – 2014-07-11
• [Presentation] Constraints for oceanic redox conditions from Fe speciation analysis of 3.2 Ga DXCL-DP black shales, Cleaverville Group, Western Australia. (2014)
  • Author(s): Shiina, A., Yamaguchi, K.E., Kiyokawa, S., Ikehara, M., and Ito, T.
  • Organizer: Origins 2014
  • Place of Presentation: 奈良県新公会堂（奈良県奈良市）
  • Year and Date: 2014-07-06 – 2014-07-11
• [Presentation] 32 億年前の海底環境復元: DXCL掘削試料の炭素・硫黄同位体比について (2014)
  • Author(s): 三木 翼、清川 昌一、奈良岡 浩、高畑 直人、石田 章純、伊藤 孝、池原 実、山口 耕生、坂本 亮、 佐野 有司
  • Organizer: 日本地球惑星科学連合2014年大会
  • Place of Presentation: パシフィコ横浜（神奈川県横浜市）
  • Year and Date: 2014-04-28 – 2014-05-02