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Oligocene/early Miocene major E/W-shortening and NW-oriented sinistral slip with associated wrench-fault assemblage in the Oman Mountains related to oblique Arabia-India convergence
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  • Andreas Scharf,
  • Frank Mattern,
  • Robert Bolhar,
  • Ivan Callegari,
  • Paul Erik Mattern,
  • Uwe Ring
Andreas Scharf
Sultan Qaboos University

Corresponding Author:[email protected]

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Frank Mattern
Sultan Qaboos University
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Robert Bolhar
University of the Witwatersrand
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Ivan Callegari
German University of Technology, Department of Applied Geosciences (AGEO)
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Paul Erik Mattern
Freie Universität Berlin
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Uwe Ring
Department of Geological Sciences, Stockholm University
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Abstract

Field survey, satellite image interpretation, geological map interpretation, literature review, GPlates reconstruction and LA-ICP-MS U-Pb dating of synkinematic calcites demonstrate that ~E/W-shortening in eastern Oman was significant and related to oblique convergence of Arabia and India from 32.5 to 20 Ma. Approximately N/S-oriented compressive structures, WNW to NNW-striking sinistral faults and ~E/W-oriented normal faults characterize a major shear zone in the eastern Oman Mountains (Hajar Shear Zone, HSZ) and its wrench-fault assemblage within an area spanning ~250 km x ~50 km. More than 10,000 mostly NW-striking lineaments as deduced from satellite image interpretation and numerous faults/folds indicate that strain of the HSZ is widely distributed but concentrated along WNW to NNW-striking major faults/fault zones at the SW margin of the Saih Hatat Dome. These faults/fault zones represent reactivated basement faults. GPlates reconstructions reveal that N-drifting India rotated 8° counter-clockwise with respect to fixed Arabia from 32.5 to 20 Ma, leading to ~100-135 km E/W-convergence between both plates (minimum value). This convergence created the sinistral HSZ with a displacement of a few to several tens of kilometers. Independently from the GPlates time constraints, two U-Pb ages of synkinematic calcites, crystallized along faults during HSZ movement, yield compatible ages of 30.08 ±0.47 and 22.31 ±2.15 Ma (2 standard error). E/W-shortening also affected the northern Oman Mountains, creating the ~N/S-oriented Hagab Thrust in the Musandam Peninsula and the Jabal Hafit Anticline.