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Geochemical characterization of the Oman Crust-Mantle transition zone, OmanDP Holes CM1A and CM2B
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  • Fatma Kourim,
  • Mathieu Rospabé,
  • Nick Dygert,
  • Ssysntani Chatterjee,
  • Eiichi Takazawa,
  • Kuo-Lung Wang,
  • Marguerite Godard,
  • Mathieu Benoit,
  • Mmmanouil Giampouras,
  • Keisuke Ishii,
  • Damon Teagle,
  • Matthew Cooper,
  • Peter Kelemen
Fatma Kourim
Institute of Earth Sciences, Academia Sinica, Academia Road, Nangang, Taipei 11529, Taiwan.

Corresponding Author:k.fatna@gmail.com

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Mathieu Rospabé
Research Institute for Marine Geodynamics (IMG)
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Nick Dygert
Department of Earth & Planetary Sciences
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Ssysntani Chatterjee
Department of Geology
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Eiichi Takazawa
Department of Geology
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Kuo-Lung Wang
Institute of Earth Sciences
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Marguerite Godard
Géosciences Montpellier
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Mathieu Benoit
Géosciences Environnement Toulouse (GET)
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Mmmanouil Giampouras
Instituto Andaluz de Ciencias de la Tierra (IACT)
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Keisuke Ishii
Department of Geology
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Damon Teagle
School of Ocean & Earth Science
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Matthew Cooper
National Taiwan University
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Peter Kelemen
Lamont–Doherty Earth Observatory
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The transition from the gabbroic oceanic crust to the residual mantle harzburgites of the Oman ophiolite has been drilled at Holes CM1A and CM2B (Wadi Tayin massif) during Phase 2 of the International Continental Scientific Drilling Program (ICDP) Oman Drilling Project (OmanDP) (Nov. 2017-Jan. 2018). In order to unravel the formation processes of ultramafic rocks in the Wadi Tayin massif (CM) crust-mantle transition zone and deeper in the mantle sections beneath oceanic spreading centers, our study focuses on the whole rock major and trace element compositions (together with CO2 and H2O concentrations) of these ultramafic rocks (56 dunites and 49 harzburgites). Despite extensive serpentinization and some carbonation, most of the trace element contents (REE, HFSE, Ti, Th, U) record high temperature, magmatic process-related signatures. Two major trends are observed, with good correlations between (1) Th and U, Nb and LREE on one hand, and between (2) HREE, Ti and Hf on the other hand. We interpret the first trend as the signature of late melt/peridotite interactions as LREE are known to be mobilized by such processes (‘lithospheric process’), and the second trend as the signature of the initial mantle partial melting (‘asthenospheric process’), with little or no overprint from melt/rock reaction events.
Apr 2022Published in Journal of Geophysical Research: Solid Earth volume 127 issue 4. 10.1029/2021JB022694