Earth’s oldest mantle peridotites show entire record of late accretion

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  • J. van de Löcht
    1Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Straße 49b, 50674 Cologne, Germany
  • J.E. Hoffmann
    2Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstraße 74-100, 12249 Berlin, Germany
  • C. Li
    2Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstraße 74-100, 12249 Berlin, Germany
  • Z. Wang
    3China University of Geosciences, No. 388 Lumo Road, 430074 Wuhan, China
  • H. Becker
    2Institut für Geologische Wissenschaften, Freie Universität Berlin, Malteserstraße 74-100, 12249 Berlin, Germany
  • M.T. Rosing
    4NordCEE (Nordic Center for Earth Evolution), Copenhagen University, Øster Voldgade 3-5, 1350 Copenhagen, Denmark
  • R. Kleinschrodt
    1Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Straße 49b, 50674 Cologne, Germany
  • C. Münker
    1Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Straße 49b, 50674 Cologne, Germany

説明

<jats:title>Abstract</jats:title> <jats:p>An important issue in Earth’s earliest history is the timing and mixing history of the late accreted material that supplied highly siderophile elements to Earth’s mantle after core segregation. Previously, constraints on ancient mantle processes could only be obtained indirectly from mantle-derived magmas such as basalts or komatiites. Relics of Eoarchean (older than 3.8 Ga) mantle were proposed to occur within the Eoarchean terrains of western Greenland. Here we provide geochemical evidence, including combined platinum group element (PGE) and Re-Os isotope data, showing that modern mantle-like peridotites occur at two localities in southwest Greenland. Rhenium-depletion model ages of these peridotites are mostly of Eoarchean age, in accord with U-Pb zircon ages of crosscutting granitoid intrusives. PGE abundances and patterns are similar to those of modern depleted mantle peridotites. For the first time, such patterns provide conclusive evidence for preservation of Eoarchean depleted mantle rocks that are clearly distinguishable from magmatic cumulates or komatiites. Abundances of Os, Ir, and Ru combined with Os isotope compositions in the Greenland peridotites reveal that primitive late accreted material appears to have been efficiently mixed into the sampled mantle domains by Eoarchean time.</jats:p>

収録刊行物

  • Geology

    Geology 46 (3), 199-202, 2018-01-04

    Geological Society of America

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