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Crustal and mantle deformation inherited from obduction of the Semail ophiolite (Oman) and continental collision (Zagros)
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  • Simone Pilia,
  • Simone Pilia,
  • A youb Kaviani,
  • Mike Searle,
  • Pierre Arroucau,
  • Mohammed Ali,
  • Anthony Watts
Simone Pilia
University of Cambridge, University of Cambridge

Corresponding Author:[email protected]

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Simone Pilia
University of Cambridge, University of Cambridge
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A youb Kaviani
Goethe University, Goethe University
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Mike Searle
University of Oxford, University of Oxford
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Pierre Arroucau
Electricité de France, Electricité de France
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Mohammed Ali
Khalifa University of Science and Technology, Khalifa University of Science and Technology
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Anthony Watts
University of Oxford, University of Oxford
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Abstract

A common deviation from typical subduction models occurs when thrust sheets of oceanic-crust and upper-mantle rocks are emplaced over more buoyant continental lithosphere. The archetypal example of ophiolite obduction is the Semail ophiolite in the United Arab Emirates (UAE)-Oman orogenic belt, formed and obducted onto the Arabian continental margin during the Late Cretaceous. The Strait of Hormuz syntaxis, the northern extent of the UAE-Oman mountains, marks the transition from ocean-continent convergence in the Gulf of Oman to continental collision along the Zagros Mountains. Based on new seismic data from a focused recording network, we infer crustal and mantle deformation in the northeastern corner of the Arabian plate (including the southern Zagros and the UAE-Oman mountains), using observations from anisotropic tomography and shear-wave splitting measurements. We recover a change of ~90˚ in the axis of fast-anisotropic orientations in the crust from the Zagros to the UAE-Oman mountain belt, consistent with the dominant strike of the orogenic belts. We also find evidence for localized fossil deformation in the lithospheric mantle underlying the UAE-Oman mountain range, possibly related to stress-induced tectonism triggered by underthrusting of the proto-Arabian continental margin beneath the overriding Semail ophiolite. These orientations, averaging 15˚ anticlockwise, provide the first geophysical verification of geological