Right-lateral transpressional tectonics along the boundary between Lut and Tabas blocks (Central Iran)

One of the major issues for understanding the tectonic evolution of continental regions is how pre-existing discontinuities influence the style and distribution of deformation, which is often not obviously and uniquely connected to the plate-boundary kinematics. Iran represents one of the most instructive regions to study continental deformation, as here the present-day Arabia Eurasia convergence is accommodated in a very wide area over a range of structures. The tectonic boundary between the Lut and the Tabas blocks of Central Iran currently accommodates part of the Arabia Eurasia convergence by right-lateral strike-slip faults, associated with NNW-SSE oriented fold-related thrust. During Middle-Late Jurassic, this boundary was the location of a large-scale shelf-lagoon carbonate platform-slope-to-basin depositional system, mainly controlled by the activity of a N S oriented normal fault system. In this study, the geometry and the kinematics of the deformation at the tectonic boundary between the Lut and the Tabas blocks, are reconstructed from an integrated anisotropy of magnetic susceptibility (AMS) and structural analysis in the Upper Jurassic Garedu Red Beds Fm., outcropping at the core of a NNE-SSW oriented syncline in the northern Shotori Range. AMS and structural results indicate that the Upper Jurassic Garedu Red Beds Fm. syncline can be defined as a transected fold, where the mismatch between fold hinge and magnetic fabric/cleavage is about 15 degrees counter-clockwise, suggesting that this fold system formed as a consequence of right-lateral transpressional tectonics. Results from this study thus document the evolution of Jurassic normal faults to a transpressional tectonic boundary between the Tabas and Lut crustal blocks sometime between the Lower Cretaceous and Palaeocene.