Study on changing of stress Field and it,s role on deformation of Faraghan Structure in Eastern Zagros

In the east of high Zagros – in Faraghan Anticline- sedimentary cover with more than 10 km thickness has decoupled from basement above the Hormuz salt and has deformed. Mention anticline is cut by High Zagros Fault. By attention to lack of paleostress study and kinematic interpretation on north east of Fars Arc structures, in this paper we reconstructed stress field and interoperated its role in evolution of Faraghan Anticline. Inversion method used for determination of reduced stress tensor parameters and discrimination faults of every brittle tectonic phase. Maximum shortening axis determined by using Stylolite's and attitude of Minimum main stress determined by using veins. The present stress field was calculated by inversion of earthquake focal mechanism data. According to our data and the deduced results, some of veins developed with an N27° - 29°E direction of σ1 stress axis before late of middle Miocene (before folding and faulting). During the late Miocene, sedimentary cover deformed as detachment and faults related folds in a general compressional stress regime with an N27° - 29°E direction of σ1. The basement faults were reactivated during late Miocene- early Pliocene in a general strike slip regime with an N4°E direction of σ1 stress axis. The High Zagros Fault was reactivated at that time and cross- cuts the entire cover section and its associated structures. In the late Pliocene, direction of σ1 stress axis temporally changed to N025°W in strike slip tectonic regime. Strike- slip and reverse faults were reactived in new stress field. Earthquakes Focal mechanism data analysis indicate that direction of σ1 stress axis is N-S now.