TY  - JOUR
A1  - Weidle, Christian
A1  - Wiesenberg, Lars
A1  - El-Sharkawy, Amr
A1  - Krüger, Frank
A1  - Scharf, Andreas
A1  - Agard, Philippe
A1  - Meier, Thomas
T1  - A 3-D crustal shear wave velocity model and Moho map below the Semail Ophiolite, eastern Arabia
T2  - Geophysical journal international
N2  - The Semail Ophiolite in eastern Arabia is the largest and best-exposed slice of oceanic lithosphere on land. Detailed knowledge of the tectonic evolution of the shallow crust, in particular during and after ophiolite obduction in Late Cretaceous times is contrasted by few constraints on physical and compositional properties of the middle and lower continental crust below the obducted units. The role of inherited, pre-obduction crustal architecture remains therefore unaccounted for in our understanding of crustal evolution and the present-day geology. Based on seismological data acquired during a 27-month campaign in northern Oman, Ambient Seismic Noise Tomography and Receiver Function analysis provide for the first time a 3-D radially anisotropic shear wave velocity (V-S) model and a consistent Moho map below the iconic Semail Ophiolite. The model highlights deep crustal boundaries that segment the eastern Arabian basement in two distinct units. The previously undescribed Western Jabal Akhdar Zone separates Arabian crust with typical continental properties and a thickness of similar to 40-45 km in the northwest from a compositionally different terrane in the southeast that is interpreted as a terrane accreted during the Pan-African orogeny in Neoproterozoic times. East of the Ibra Zone, another deep crustal boundary, crustal thickness decreases to 30-35 km and very high lower crustal V-S suggest large-scale mafic intrusions into, and possible underplating of the Arabian continental crust that occurred most likely during Permian breakup of Pangea. Mafic reworking is sharply bounded by the (upper crustal) Semail Gap Fault Zone, northwest of which no such high velocities are found in the crust. Topography of the Oman Mountains is supported by a mild crustal root and Moho depth below the highest topography, the Jabal Akhdar Dome, is similar to 42 km. Radial anisotropy is robustly resolved in the upper crust and aids in discriminating dipping allochthonous units from autochthonous sedimentary rocks that are indistinguishable by isotropic V-S alone. Lateral thickness variations of the ophiolite highlight the Haylayn Ophiolite Massif on the northern flank of Jabal Akhdar Dome and the Hawasina Window as the deepest reaching unit. Ophiolite thickness is similar to 10 km in the southern and northern massifs, and <= 5 km elsewhere.
KW  - Composition and structure of the continental crust
KW  - Asia
KW  - Body waves
KW  - Seismic anisotropy
KW  - Seismic tomography
KW  - Surface waves and free oscillations
Y1  - 2022
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/64235
SN  - 0956-540X
SN  - 1365-246X
VL  - 231
IS  - 2
SP  - 817
EP  - 834
PB  - Oxford University Press
CY  - Oxford
ER  -