Crustal and mantle deformation inherited from obduction of the Semail ophiolite (Oman) and continental collision (Zagros)

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