Geometric- kinematic analysis of the Kalmard fault zone, north of Ozbak-Kuh, central Iran

Kalmard fault is considered as one of the fundamental faults in central Iran zone. The Ozbak Kuh mountains with a NE-SW strike are located in central Iran in the Kalmard fault zone. Hence, analyze the folds and faults in this deformed zone can aid in the understanding of structural evolution of this area in central Iran. In this study, field operations and geometric-kinematic analysis of folds and faults, also study of their structural evolution are integrated in order to provide a better understanding of the structural evolution of the Ozbak Kuh area. The results display that before Cretaceous period the Ozbak-Kuh area was influenced by a compressional regime with a prependicular trend with respect to the Kalmrad fault that it caused the formation of folds and faults paralell to folds axial plane trends, after that compressional regime changing to a dextral strike slip regime in Cenozoic in direction of NE- SW, all structures in the study area such as, faults, folds axial plain and other related structures were influenced by the aforementioned strike slip stress. Generally the geometric- kinematic pattern of faults in the study area regarding to the major and R, P, R', and X faults is kind of simple shear and contraction parallel to deformed zone. In this pattern the simple shear is dominant and compression is trivial component. The mechanism of the faults in the study area shows that the deformation of the Ozbak Kuh mountains is toward the final stages of simple shear. The multiple steps of deformation, simple shear movements and intensity of deformation in the study area caused that the strike of all structures is to be in direction of NE-SW that it is parallel to the main fault zone.