Structural evolution and active tectonic of Mianrahan area, northeast of Kermanshah

The studied area located at the main suture zone of Zagros in the northeastern of Kermanshah. To do structural analysis in this area, six structural sections have been drawn perpendicular to structures direction. Structures and faults with different mechanism show that the studied area has passed two tectonic phases from Cretaceous up to present. The first phase which is a Compression phase, started from Cretaceous and lasted until Miocene. The created faults in this phase are thrusts with vast displacements in which the Main Zagros Thrust is the most important one of them. The second tectonic phase which is very young and active acts as a Transpressional system. The main structures created in second phase are dextral faults of Mianrahan and Sahne. These tow faults are part of Main Recent Fault and created some secondary structures such as Dinevar pull apart and flower structure on Sahne fault. Finally structural evolution model of the area has been expressed in six steps according to the relation among the structures and layers with different ages. During these steps, faults with the same dirctions but different mechanism have been created which demonstrates the counterclockwise rotation of stress axis σ1 since Cretaceous.