Kinematics of the Great Kavir fault inferred from a structural analysis of the Pees Kuh Complex, Jandaq area, central Iran
Published:December 21, 2017
Sasan Bagheri, Razieh Madhanifard, Foruzan Zahabi, 2017. "Kinematics of the Great Kavir fault inferred from a structural analysis of the Pees Kuh Complex, Jandaq area, central Iran", Tectonic Evolution, Collision, and Seismicity of Southwest Asia: In Honor of Manuel Berberian’s Forty-Five Years of Research Contributions, Rasoul Sorkhabi
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A significant part of the convergence between the Iranian and Arabian plates since the late Cenozoic has been accommodated by several strike-slip faults, especially in the eastern and central areas of Iran. The Great Kavir fault is one of the cases in which there is little consensus regarding its kinematics, mechanism of development, and tectonic history, mainly due to a lack of detailed studies. Field and satellite image studies of the Pees Kuh Complex, a well-preserved Cenozoic structure that developed upon the Great Kavir fault near Jandaq, in central Iran, suggest a virtually perfect, positive-flower structure. It is argued that the Pees Kuh Complex is the result of a combination of both left strike-slip and reverse dip-slip displacements on the Great Kavir fault. The main structural elements comprising this flower structure are as follows: a Paleogene sedimentary assemblage, composed of an array of thrust faults with NW to EW trends, thrusted upon the Great Kavir block; a few reverse faults with N to NW dips at the southern side of the Great Kavir fault; several synthetic en echelon faults; and a number of antithetic NW-trending en echelon faults. In addition, left-stepping en echelon folds with NW-trending axial planes are recognizable. The Pees Kuh Complex shows a thrust sequence of an upward-verging antiform structure including overturned folds formed of middle to late Eocene marl and sandstone beds. These sheets have a nearly vertical position at their roots, mainly confined to the Great Kavir fault, which changes to a horizontal position further along the fault. Because the thrusts transported middle-late Eocene rocks atop Oligocene-Miocene red beds and are, in turn, covered by Pliocene-age continental beds, the age of the Pees Kuh Complex is inferred to be younger than the Miocene. Considerable left-lateral displacement of the Great Kavir fault in the Jandaq area is confirmed by geometrically measured counterclockwise rotation of ~20° of the faulted blocks around approximately vertical axes relative to the Great Kavir fault in the Godar-e-Siah area. This study, in addition to other previous lithological evidence gathered from the Jandaq area, demonstrates deformation of the Pees Kuh Complex as a reactivation of an older regional fracture, such as a suture zone, as the Paleogene sedimentary rocks were subjected to a different stress field in late Cenozoic times.