Documentation of the Sirjan Orocline in the southeast Sanandaj-Sirjan Zone, Iran

At the southeastern part of the Sanandaj-Sirjan Zone of Iran, a group of structural elements outline a large-scale arc curvature around a vertical axis. This curvature comprises several elongated structural elements and their dividing faults, axial-fold traces, layering, and foliation. The most frequent lithological units include Paleozoic metamorphic rocks, Mesozoic-Paleogene sedimentary rocks, and Mesozoic magmatic-ophiolitic complex disposed in several anticlines and synclines, forming a horseshoe-shaped structure with a 240-km arc length and a 90-km wavelength. We name this structure the Sirjan Orocline, and characterize this structure here through field observations and satellite image analyses. The Sirjan Orocline formed during the late Eocene-Oligocene related to the most significant deformation event after regional metamorphism. The final form of this structural arc is affected by a younger tectonic event that compressed and transected this structure.