Effects of the Sabzpushan Transverse Fault on the Development of Restraining Zones in the Chaghal Anticline, Zagros Fold-Thrust Belt

The Zagros fold-thrust belt has been cut out by various transverse faults with segments displaying en-echelon pattern. Depending on the type of overlapping and fault mechanisms، restraining and releasing zones have been developed between these en-echelon segments. The NW-trending dextral Sabzpushan fault is one of these transverse strike-slip faults located in the Fars province of the Zagros belt. Since the Sabzpushan fault zone consists of several en-echelon segments of clockwise pattern، restraining zones have been generated between them. One of these restraining zones is developed on the NW nose of the Chaghal anticline. Detailed field studies and interpretation of satellite images resulted in identification of several dextral en-echelon faults in the western part of the Chaghal anticline. This fault zone consists of two en-echelon faults called Qir and Harm. Different kinds of structures such as dextral faults with reverse component، thrust faults، minor duplexes and young minor folds were mapped in these restraining zones. These structural assemblages are similar to those that are developed in the restraining zones produced in physical models of en-echelon strike-slip faults. In addition، similar restraining zones which are also observed across the Ghol Ghol and Sefidar anticlines to the south and north of the Chaghal anticline، respectively، are attributed to other en-echelon segments of clockwise array along the Sabzpushan fault zone. These dextral en-echelon faults along the Sabzpushan fault، which are interpreted as surface ruptures in the sedimentary cover with basal detachment zone، formed as a result of the activity of Sabzpushan fault in the basement.