The long-term evolution of the Doruneh Fault region (Central Iran): A key to understanding the spatio-temporal tectonic evolution in the hinterland of the Zagros convergence zone

摘要

A better understanding of intraplate deformation requires the knowledge of the space-time scales involved in its development and to decipher possible links with the dynamic evolution of the plate boundaries. Central Iran provides an ideal test site to approach this scientific issue, since it is characterised by a prolonged history of Mesozoic-Cenozoic intraplate deformation that has been interfering with the spatio-temporal re-organization of the Zagros convergence zone along the Eurasia plate boundary. This study focus on the Doruneh Fault (DF) region that is considered as the northern mechanical boundary of the Central East Iranian Microcontinent. By combining field investigations with apatite low-temperature thermochronology, we present a revised tectono-stratigraphic scenario for the DF region, typified by a punctuated history of fault-related exhumation, burial and cooling history back to the Upper Cretaceous. When framed at regional scale, these results attest that the Zagros convergence zone, and its hinterland domain were fully mechanically coupled since ca. 40-35Ma, a time lapse that is here referred as to the onset of continental collision along the Arabia-Eurasia plate boundary. In this scenario, the DF region operated throughout the Cenozoic as a major zone of residual stress accommodation and transfer in the hinterland domain of the Zagros convergence zone. Results of this study also suggest that the tectonic evolution along the Arabia-Eurasia plate boundary was modulated by the plate-boundary dynamics and by the modes of tectonic reactivation of the intracontinental weak zones of Central Iran and at its tectonic boundaries.