The role of active strike-slip faults and opposite vertical axis rotations in accommodating eurasia-arabia shortening in central iran

Abstract

In Central Iran, most of the Late Cenozoic to Present shortening has been accomplished in the Zagros, in the Alborz, and Kopeh-Dagh mountain ranges. Between these active mountain belts, a minor amount of shortening is observed and the deformation style is characterized by active strike-slip faults that bound relatively aseismic blocks. Two main strike-slip fault systems are presently active in different regions of Central Iran: South of latitude 34°N, active deformation is accommodated on ∼N–S oriented right-lateral strike-slip faults, and north of latitude 34°N, E–W left-lateral strike slip faults prevail.In this work, we investigated two different structures, representative of the two different strike-slip systems occurring in Central Iran: the Yazd fold system located in an area dominated by the occurrence of NNW-SSE oriented right-lateral strike slip faults, and the Ferdows fold system that developed at the western termination of the E–W left-lateral strike-slip Dasht-e-Bayaz fault. Paleomagnetic results show opposite vertical-axis rotations related to the different orientation and sense of movement of strike-slip fault systems, suggesting that in Central Iran the N–S oriented right-lateral and E–W oriented left-lateral strike-slip faults play significant roles in accommodating the Arabia-Eurasia convergence, by rotating counterclockwise and clockwise in the horizontal plane, respectively.