The Kinematic Analysis and Evolution of the Stress Fields in the Zagros Foreland Folded Belt, Fars Salient, Iran

The NWSE trending Zagros Orogenic Belt was initiated during the convergence of the AfroArabian continent and the Iranian microcontinent in the Late Cretaceous. Ongoing convergence is confirmed by intense seismicity related to compressional stresses collisionrelated in the Zagros Orogenic Belt by reactivation of an early extensional faulting to latter compressional segmented strikeslip and dipslip faulting. These activities are strongly related either to the deepseated basement fault activities (deepseated earthquakes) underlies the sedimentary cover or gently dipping shallowseated décollement horizon of the rheological weak rocks of the InfraCambrian Hormuz salt. The Compressional stress regimes in the different units plays an important role in controlling the stress conditions between the different units within the sedimentary cover and basement. A significant set of nearly NS trending rightlateral strikeslip faults exists throughout the study area in the Fars area in the Zagros Foreland Folded Belt. Faultslip and focal mechanism data, were analyzed using the stress inversion method to reconstruct the paleo and recent stress conditions. The results suggest that the current direction of maximum principal stress averages N19°E, with N38°E that for the past from Cretaceous to Tertiary, (although a few sites on the KareBas fault yield a different direction). The results are consistent with the collision of the AfroArabian continent and the Iranian microcontinent. The difference between the current and paleostress directions indicates an anticlockwise rotation in the maximum principle stress direction over time. This difference resulted from changes in the continental convergence path, but was also influenced by the local structural evolution, including the lateral propagation of folds and the presence of several local décollement horizons that facilitated decoupling of the deformation between the basement and sedimentary cover. The obliquity of the maximum compressional stress into the fault trends reveal a typical stress partitioning of thrust and strikeslip motion in the Kazerun, KareBas, SabzPushan, and Sarvestan fault zones, that caused these fault zones behave as segmented strikeslip and dipslip faults (Sarkarinejad et al., 2018).