Oceanic Transform as a water inlet to earth's interior

• Project/Area Number: 15K05263
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: The University of Tokyo
• Principal Investigator: OKINO KYOKO 東京大学, 大気海洋研究所, 教授 (30313191)
• Co-Investigator(Kenkyū-buntansha): 町田 嗣樹 千葉工業大学, 次世代海洋資源研究センター, 上席研究員 (40444062) ; 川口 慎介 国立研究開発法人海洋研究開発機構, 深海・地殻内生物圏研究分野, 研究員 (50553088)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000); Fiscal Year 2017: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2016: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000); Fiscal Year 2015: ¥2,600,000 (Direct Cost: ¥2,000,000、Indirect Cost: ¥600,000)
• Keywords: トランスフォーム断層 / 海洋地殻 / 蛇紋岩 / 水 / 重力異常 / 中央海嶺玄武岩 / メタン濃度 / 海洋トランスフォーム断層 / 中央海嶺 / 重磁力観測 / 流体湧出 / 磁気観測

Outline of Final Research Achievements

The contribution of seawater infiltration along oceanic transform faults is not negligible in global water flux, however, the degree and spatial extent of serpentinization around the faults system remain poorly constrained. The R/V Hakuho-maru cruise was conducted in early 2016, investigating the nature of these long-offset oceanic transform faults (OTF) as a water inlet into earth's interior. 1) Detailed bathymetry and gravity measuremen reveals the detailed fault distribution and evolutionary process of OTF and a possible density increase beneath the OTF, indicating sepentinization of lithospheric mantle. 2) Surface magnetic survey is used to reconstruct the seafloor spreading history of the area. Deep-tow mangetic survey across the OTF shows no clear anomalous signature. 3) Major and minor compositions of dredged rock samples and their alteration processes are studied. 4) Anomalous water mass is detected in deeper part of the OTF valley. Methane analysis is now going on.

Research Products

• [Int'l Joint Research] モーリシャス海洋研究所(モーリシャス)
• [Int'l Joint Research] KORDI(韓国)
• [Int'l Joint Research] 韓国海洋科学技術院(韓国)
• [Int'l Joint Research] 韓国海洋科学技術院(韓国)
• [Journal Article] Petit-spot as definitive evidence for partial melting in the asthenosphere caused by CO2 (2017)
  • Author(s): Machida Shiki、Kogiso Tetsu、Hirano Naoto
  • Journal Title: Nature Communications Volume: 8 Issue: 1 Pages: 14302-14302
  • DOI: 10.1038/ncomms14302
  • NAID: 120005971001
  • Peer Reviewed / Open Access
• [Journal Article] Origin of methane-rich natural gas at the West Pacific convergent plate boundary (2017)
  • Author(s): Sano Y., Kinoshita N., Kagoshima T., Takahata N., Sakata S., Toki T., Kawagucci S., Waseda A., Lan T., Wen H., Chen A., Yang T. F., Guodong Z., Tomonaga Y., Roulleau E., Pinti D. L.
  • Journal Title: Scientific Reports Volume: 7 Issue: 1 Pages: 15646-15646
  • DOI: 10.1038/s41598-017-15959-5
  • NAID: 120006383299
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Deepest and hottest hydrothermal activity in the Okinawa Trough: the Yokosuka site at Yaeyama knoll (2017)
  • Author(s): Miyazaki J, S Kawagucci, A Makabe, A Takahashi, K Kitada, J Torimoto, Y Matsui, E Tasumi, T Shibuya, K Nakamura, S Horai, S Sato, J Ishibashi, H Kanzaki, S Nakagawa, M Hirai, Y Takaki, K Okino, HK Watanabe, H Kumagai, C Chen
  • Journal Title: Royal Society Open Science Volume: 4
  • Open Access
• [Journal Article] Variation in magnetic properties of serpentinized peridotite exposed on the Yokoniwa Rise, Central Indian Ridge: Insights into the role of magnetite in serpentinization (2016)
  • Author(s): Fujii M., Okino K., Sato H., Nakamura K., Sato T. and Yamazaki T.
  • Journal Title: Geochemistry, Geophysics, Geosystems Volume: 17
  • Peer Reviewed
• [Journal Article] Fluid chemistry in the Solitaire and Dodo hydrothermal fields of the Central Indian Ridge (2016)
  • Author(s): Kawagucci, S., Miyazaki, J., Noguchi, T., Okamura, K., Shibuya, T., Watsuji, T., Nishizawa, M., Watanabe, H., Okino, K., Takahata, N., Sano, Y., Nakamura, K., et al.
  • Journal Title: Geofluids Volume: 16 Issue: 5 Pages: 988-1005
  • DOI: 10.1111/gfl.12201
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Hydrogen and carbon isotope systematics in hydrogenotrophic methanogenesis under H2-limited and -enriched conditions: Implications for the origin of methane and its isotopic diagnosis. (2016)
  • Author(s): Okumura T., Kawagucci S., Saito Y., Matsui Y., Takai K., Imachi H.
  • Journal Title: Progress in Earth and Planetary Science. Volume: 3 Issue: 1 Pages: 14-14
  • DOI: 10.1186/s40645-016-0088-3
  • Peer Reviewed / Open Access / Acknowledgement Compliant
• [Journal Article] Pre-subduction metasomatic enrichment of the oceanic lithosphere induced by plate flexure (2016)
  • Author(s): S. Pilet, N. Abe, L. Rochat, M. -A.Kaczmarek, N. Hirano, S. Machida, D. M. Buchs, P. O. Baumgartner & O. Müntener
  • Journal Title: Nature Geoscience Volume: 9 Issue: 12 Pages: 898-903
  • DOI: 10.1038/ngeo2825
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Origin of magnetic highs at ultramafic hosted hydrothermal systems: Insights from the Yokoniwa site of Central Indian Ridge (2016)
  • Author(s): Fujii M., Okino, K., Sato, T., Sato H., and Nakamura K.
  • Journal Title: Earth and Planetary Science Letters Volume: 441 Pages: 26-37
  • DOI: 10.1016/j.epsl.2016.02.018
  • Peer Reviewed
• [Presentation] Tectonics of long-offset oceanic transform faults along the Central Indian Ridge (2017)
  • Author(s): 沖野郷子・島伸和・藤井昌和・町田嗣樹
  • Organizer: 日本地球惑星科学連合大会
• [Presentation] トランスフォーム断層と水 (2017)
  • Author(s): 沖野郷子
  • Organizer: 海洋リソスフェアの蛇紋岩化作用と物理・化学・生物プロセスーInterRidge-Japan研究集会ー
• [Presentation] トランスフォーム断層における地磁気異常の要因の推定 (2017)
  • Author(s): 古川優和・藤井昌和・島伸和・沖野郷子
  • Organizer: 海洋リソスフェアの蛇紋岩化作用と物理・化学・生物プロセスーInterRidge-Japan研究集会ー
• [Presentation] Mid-ocean ridge processes and hydrothermalism along the Central Indian Ridge: summary of past Japanese expeditions (2016)
  • Author(s): Okino K.
  • Organizer: KIOST(Korea Institute of Ocean Science and Technology) Seminar
  • Place of Presentation: 安山（韓国）
  • Invited
• [Presentation] Tectonics of long-offset oceanic transform faults along the Central Indian Ridge (2016)
  • Author(s): Okino K., Seama N., Fujii M. and Machida S.
  • Organizer: American Geophysical Union 2016 Fall Meeting
  • Place of Presentation: San Francisco（USA)
• [Presentation] KH-15-5 白鳳丸研究航海速報：長大トランスフォーム断層と海嶺活動 CIR13-18°S (2016)
  • Author(s): 沖野郷子・島伸和・砂村倫成・町田嗣樹・KH-15-5研究者
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ(千葉県・千葉市）
• [Presentation] フラクチャーゾーン、トランスフォーム断層を横切る深海地磁気調査 (2016)
  • Author(s): 島伸和・北川高行・沖野郷子・藤井昌和・中東和夫・岡本理・古川優和・小林拓史・野木義史
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ(千葉県・千葉市）
• [Presentation] Review of Japanese geophysical surveys of Indian Ocean Ridges (2015)
  • Author(s): Seama N., Okino K., and Sato T.
  • Organizer: 2nd InterRIdge Workshop: Circus Antarctic Ridges
  • Place of Presentation: Incheon, Korea
  • Year and Date: 2015-10-13
  • Int'l Joint Research
• [Presentation] Review of Japanese TAIGA project I. Indian Ocean (2015)
  • Author(s): Okino K.
  • Organizer: InterRidge 3rd Theoretical Institute
  • Place of Presentation: Hangzhou, China
  • Year and Date: 2015-09-25
  • Int'l Joint Research / Invited