An investigation into the fault patterns in the Chadegan region, west Iran: Evidence for dextral brittle transpressional tectonics in the Sanandaj–Sirjan Zone

The NW–SE trending Sanandaj–Sirjan Zone (SSZ) is the internal part of the Zagros continental collision zone, which mainly consists of metamorphic rocks deformed in a dextral transpressional zone. This dextral transpression is attributed to brittle deformation related to late Cenozoic Arabia–Eurasia oblique continental collision. Major NW-trending faults, including the Dalan, Garmdareh, Yasechah, Sheida, and Ben faults, are reverse faults with a dextral strike-slip component. These faults were displaced by NW-trending synthetic and NE-trending antithetic faults. There are also E-trending thrusts and N-trending normal faults developing in directions that are, respectively, almost normal and parallel to the major shortening direction. The NW-trending Ben, Yasechah, and Sheida faults are NE-dipping faults, and the Dalan and Garmdareh faults are SW-dipping faults. These faults indicate the presence of a transpressive flower structure zone that probably led to the exhumation of Jurassic high-grade metamorphic rocks, such as eclogite, in the central part of the study area.

► Major faults are dextral reverse faults generating a dextral transpressional zone.
► NW-trending synthetic and NE-trending antithetic faults displace the major faults.
► Major faults have opposite dips, indicating a transpressive flower structure.