Re–Os isotope geochemistry in the surface layers of ferromanganese crusts from the Takuyo Daigo Seamount, northwestern Pacific Ocean Re–Os isotope geochemistry in the surface layers of ferromanganese crusts from the Takuyo Daigo Seamount, northwestern Pacific Ocean

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Author(s)

    • TOKUMARU AYAKA Tokumaru Ayaka
    • Department of Earth and Planetary Science, The University of Tokyo|Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
    • SUZUKI KATSUHIKO [他] Nozaki Tatsuo
    • Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)|Submarine Resources Research Project (SRRP), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)|Department of Systems Innovation, The University of Tokyo
    • Suzuki Katsuhiko
    • Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)|Submarine Resources Research Project (SRRP), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
    • Goto Kosuke T.
    • Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)|Geological Survey of Japan (GSJ), National Institute of Advanced Industrial Science and Technology (AIST)
    • Chang Qing
    • Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)|Submarine Resources Research Project (SRRP), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
    • Kimura Jun-ichi
    • Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)
    • Takaya Yutaro
    • Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)|Frontier Research Center for Energy and Resources (FRCER), School of Engineering, The University of Tokyo
    • Kato Yasuhiro
    • Institute for Research on Earth Evolution (IFREE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)|Submarine Resources Research Project (SRRP), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)|Department of Systems Innovation, The University of Tokyo|Frontier Research Center for Energy and Resources (FRCER), School of Engineering, The University of Tokyo
    • Usui Akira
    • Submarine Resources Research Project (SRRP), Japan Agency for Marine-Earth Science and Technology (JAMSTEC)|Department of Geology, Natural Sciences Cluster, Kochi University

Abstract

Os isotope compositions in ferromanganese crusts (Fe–Mn crusts) have been used for the dating of model ages from present to the Late Cretaceous. This dating method assumes that the Fe–Mn crusts preserve a paleo-seawater Os isotope composition at the timing of Fe–Mn crust deposition. However, available Os isotope data are limited to dredged samples without precise indications of water depths, and the Os isotope variation in relation to water depth remains uncertain. Here, we report on the Os isotope ratio data in the surface layer of Fe–Mn crusts from 956–2987 meters below sea level at the Takuyo Daigo Seamount in the northwestern Pacific Ocean collected by a remotely operated vehicle (ROV). Since the <sup>187</sup>Re/<sup>188</sup>Os ratios of the surface layer samples exhibited low values ranging from 0.020 to 0.0078, the age correction of the <sup>187</sup>Os/<sup>188</sup>Os ratios by subtracting radiogenic <sup>187</sup>Os from total <sup>187</sup>Os was not necessary for the Takuyo Daigo Fe–Mn crusts. Regardless of water depth, the surface layer samples possessed a narrow range of <sup>187</sup>Os/<sup>188</sup>Os ratio (1.003–1.017). As their Os isotope ratios were very similar to or slightly lower than the present-day seawater value (~1.06), the Fe–Mn crusts are inferred to preserve the modern seawater Os isotope composition at the investigated water depths. Therefore, Os isotope stratigraphy using Fe–Mn crusts is a powerful dating tool in paleoceanography.

Journal

  • GEOCHEMICAL JOURNAL

    GEOCHEMICAL JOURNAL 49(3), 233-241, 2015

    GEOCHEMICAL SOCIETY OF JAPAN

Codes

  • NII Article ID (NAID)
    130005074565
  • NII NACSIS-CAT ID (NCID)
    AA00654975
  • Text Lang
    ENG
  • ISSN
    0016-7002
  • NDL Article ID
    026415573
  • NDL Call No.
    Z53-R488
  • Data Source
    NDL  J-STAGE 
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