Structural and morphotectonic zonation of the Eastern Kopeh-Dagh

Different geological, structural and morphological characteristics of the eastern Kopeh-Dagh Province in NE Iran resulted in identification of several morphotectonic domains separated by major basement faults. Based on various field surveys, seismic reflection data, satellite images and cross-sections construction we introduce the fault-bounded deformed areas with different characteristics as the structural domains. These domains are the Hezar-Masjed, Darreh-Gaz- Sarakhs, and the Kopeh-Dagh foredeep from southwest to northeast, respectively. They are bounded by the Kashafrud, Mozduran, and the North Kopeh-Dagh faults. The domains were formed on the Turan plate since Middle Jurassic times when the extensional phase commenced in the Kopeh-Dagh Province. The bounding faults were initially of normal mechanism which generated grabens and half-grabens within the sedimentary basin. The maximum extension and subsidence in the basin occurred during Middle Jurassic, synchronous with the deposition of the Kashafrud Formation. Differential subsidence and configuration of the basin resulted in lateral lithofacies variations and thickness changes of the Kashafrud Formation throughout the basin. The main compression event in the Kopeh-Dagh Province started following the closure of the Neo-tethys ocean between the Iranian and Arabian plates in the Late Eocene, which caused inversion tectonics and reactivation of pre-existing normal faults as well as folding of sedimentary cover.