Investigation of stress field changes using brittle tectonic analysis in Central Iran Zone (Fahraj-Kharanagh regions)

Kharanagh Mountain which has NW-SE trend is located in Central Iran Zone, northeast Yazd block. Stratigraphically, the area is composed of Paleozoic (Devonian) to Quaternary strata. The rotation of the blocks of Central Iran, the collision of the Arabic plate with Iran, and also the structural interaction between the blocks of Central Iran during its tectonic evolution, has caused a change in the direction of the kinematic stress tensors (P-T-B). As a result, the formation of new structures and changes in paleo-structures had chronologically occurred throughout the study area. In this research, stress field variations of Mesozoic era of Fahraj-Kharanagh areas is evaluated. Hence, geological fault and fault-slip data and other tectonic and stratigraphic evidence were collected at 13 stations. The general trend of faults in the study area is NW-SE which are right-lateral strike-slip in type similar to features of Anar Fault. The change in direction of the pressure axis (P Axis) occurred counterclockwise from the vertical position of the Anar Fault to parallel to it in the period of Lower Paleozoic to Upper Cenozoic, which has changed the kinematic mechanism in the area. The presence of fault-slip in the Quaternary sediments, as well as the great thickness of the deposits in the area, indicate that the Anar fault is active presently.