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
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.