Structural evidence on strike slip Kinematic inversion of the Kushk-e-Nosrat Fault zone, Central Iran

Abstract

NW-tending faults in Central Iran are expected to represent dominant dextral components due to their orientation with respect to the northward motion of the Arabian Plate with respect to Eurasia. However, previously published works, as well as the focal mechanism solution of the area's earthquakes, indicate evidence of sinistral kinematic along the major faults in Central Iran. Here we present detail structural kinematic data on the eastern part of WNW trending Kushk-e- Nosrat (KN) Fault zone to unravel the structural architecture and regional distribution of kinematic change at the northwestern margin of Central Iran zone. We classified fault data into two dextral and sinistral kinematic categories. Based on cross-cutting relationship and the superposition of kinematic indicators the sinistral related structures are younger than the dextral one. The structural analysis of the KN Fault zone data suggests a kinematic inversion from dextral to young sinistral which is regionally attributed to the clockwise rotation of rigid South Caspian Basement Block (SCB) with respect to Eurasia.