The Talesh Mountains at the NW margin of the Iranian Plateau curve around the southwestern corner of the South Caspian Block and developed in response to the collision of the Arabian‐Eurasian Plates. The timing, rates, and regional changes in late Cenozoic deformation of the Talesh Mountains are not fully understood. In this study, we integrate 23 new apatite and zircon bedrock U‐Th/He ages and structurally restored geologic cross sections with previously published detrital apatite fission track data to reconstruct the deformation history of the Talesh Mountains. Our results reveal that slow rock exhumation initiated during the late Oligocene (~27–23 Ma) and then accelerated in the middle Miocene (~12 Ma). These events resulted in the present‐day high‐elevation and curved geometry of the mountains. The spatial and temporal distribution of cooling ages suggest that the Oligocene bending of the Talesh Mountains was earlier than in the eastern Alborz, Kopeh Dagh, and central Alborz Mountains that initiated during the late Cenozoic. Late Oligocene and middle Miocene deformation episodes recorded in the Talesh Mountains can be related to the collisional phases of the Arabian and Eurasian Plates. The lower rate of exhumation recorded in the Talesh Mountains occurred during the initial soft collision of the Arabian‐Eurasian Plates in the late Oligocene. The accelerated exhumation that occurred during final collision since the middle Miocene resulted from collision of the harder continental margin.
The Cenozoic deformation history of Central Iran has been dominantly accommodated by the activation of major intracontinental strike‐slip fault zones, developed in the hinterland domain of the Arabia‐Eurasia convergent margin. Few quantitative temporal and kinematic constraints are available from these strike‐slip deformation zones, hampering a full assessment of the style and timing of intraplate deformation in Iran and the understanding of the possible linkage to the tectonic reorganization of the Zagros collisional zone. This study focuses on the region to the north of the active trace of the sinistral Doruneh Fault. By combing structural and low‐temperature apatite fission track (AFT) and (U‐Th)/He (AHe) thermochronology investigations, we provide new kinematic and temporal constraints to the deformation history of Central Iran. Our results document a post‐Eocene polyphase tectonic evolution dominated by dextral strike‐slip tectonics, whose activity is constrained since the early Miocene in response to an early, NW‐SE oriented paleo‐σ1 direction. A major phase of enhanced cooling/exhumation is constrained at the Miocene/Pliocene boundary, caused by a switch of the maximum paleo‐σ1 direction to N‐S. When integrated into the regional scenario, these data are framed into a new tectonic reconstruction for the Miocene‐Quaternary time lapse, where strike‐slip deformation in the intracontinental domain of Central Iran is interpreted as guided by the reorganization of the Zagros collisional zone in the transition from an immature to a mature stage of continental collision.
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