Structural style and long-term slip rates in the Zagros Fold-Thrust Belt (Kurdistan Region of Iraq) derived from structural modeling, luminescence dating of river terraces and tectonic geomorphology

The Zagros Mountain Front Flexure is one of these major boundaries and forms a prominent topographic and structural step in the frontal part of the Zagros Belt. This study focuses on the Mountain Front Flexure in Kurdistan Region of Iraq. the structural style at depth is constrained from the balanced cross-section and structural forward modeling. The long-term fault slip rates are calculated for several structure from the uplifted river terraces on the banks of the Greater Zab River. The landscape maturity of several frontal anticlines was assessed to estimate difference in their relative uplift time using geomorphic indices and landscape evolution modeling. The results show that the structural evolution is represented by a multi-stage deformation. The thin-skinned deformation above the Triassic detachment was evolved first. Then, a basement thrust was evolved in the deformation and the basement thrusting is responsible for the structural step across the Mountain Front Flexure. The faults in the area are active. The basement fault below the Zagros Mountain Front Fault accommodates about 1.46±0.60 mm a-1 of slip, while a more external basement fault further to the SW accommodates less than 0.41±0.16 mm a-1. Horizontal slip rates related to detachment folding of Safin and Sarta anticlines within the Zagros Foothills are 0.40±0.10 and 1.24±0.36 mm a-1, respectively. There is difference in the landscape maturity of the frontal anticlines, and their relative uplift time. The resulting interpretation from the landscape maturity is that Akre Anticline was the first to uplift among the studied anticlines, followed by Perat Anticline and Harir Anticline. It can be inferred that uplift of the Akre and Perat anticlines started 160200 and 80100 kyr, respectively, before that of the Harir Anticline.