The Post‐Eocene Evolution of the Doruneh Fault Region (Central Iran): The Intraplate Response to the Reorganization of the Arabia‐Eurasia Collision Zone

Abstract

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.

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

“…This paper describes the tectonic evolution of the DF region as reconstructed from the exhumation history of pre‐Cenozoic bedrock and the tectono‐stratigraphic evolution of the Paleogene and Neogene sedimentary successions exposed to the northwest of the active trace of the sinistral DF (Figures ). These results complement those presented in Tadayon et al () for the eastern region of the DF, focused on the post‐Eocene history (Figure ). When integrated with the available thermochronological data and tectonic correlations at regional scale, this allows to document a polyphase tectonic evolution during the development of a major intracontinental dextral shear belt.…”

“…A major tectonic reorganization occurred in Central Iran during the Late Miocene–early Pliocene as attested by (a) enhanced exhumation in the Alborz and Talesh mountains (Axen et al, ; Madanipour et al, ; Rezaeian, Carter, Hovius, & Allen, ), (b) changes in the regional states of stress in the Kopeh Dagh region (Javidfakhr, Bellier, Shabanian, Ahmadian, & Saidi, ; Robert et al, ; Shabanian, Acocella, Gioncada, Ghasemi, & Bellier, ; Shabanian, Bellier, Abbassi, Siame, & Farbod, ), (c) oroclinal bending of the Alborz Mountains (Cifelli, Ballato, Alimohammadian, Sabouri, & Mattei, ; Mattei et al, ), (d) activation of the Zagros–Makran transfer zone (Regard et al, ) (Figure ), and (e) the collisional lithosphere overthickening of the Zagros convergence zone that became unable to sustain further shortening (Allen et al, ; Austermann & Iaffaldano, ). This time frame is also relevant for the history of the DF, as documented by (a) fault kinematic changes within the DF region (Bagheri et al, ; Javadi et al, , ; Tadayon et al, ) in consequence of a major shift in the regional paleo‐σ 1 direction from NW–SE to N–S‐oriented (Tadayon et al, ) and (b) renewed activity of dextral shearing to the south of the DF, along the Neogene–Quaternary Kuh‐Sarangi‐Kuh‐e‐Faghan fault system (Calzolari, Della Seta, et al, ; Calzolari, Rossetti, et al, ; Calzolari et al, ).…”

“…Dextral shearing is assumed to start at the Palaeocene–Eocene boundary, with the arcuate shape of the active trace of the fault resulting from the 35° counterclockwise rotation of the CEIM (Javadi et al, ). Through integration of structural and low‐temperature thermochronological data, Tadayon et al () reconstructed a post‐Eocene polyphase tectonic evolution, dominated by dextral shearing, with a major phase of enhanced cooling/exhumation starting at the Miocene/Pliocene boundary, in response to a major switch of the maximum paleo‐stress direction from NW–SE to N–S.…”

“…In the Iran region, the tectonic boundaries of the continental blocks that make‐up the hinterland domain of the Zagros convergence zone record a prolonged history of deformation and reactivation since Neoproterozoic times (Bagheri, Madhanifard, & Zahabi, ; Kargaranbafghi, Foeken, Guest, & Stuart, ; Nozaem et al, ; Ramezani & Tucker, ; Rossetti et al, ; Tadayon et al, ; Verdel et al, ). Such tectonic zones are presently dominated by wrench tectonics that accommodates and transfers the intraplate residual convergence transmitted from the collisional boundary across the Central Iran region (the assembly of the tectonic zones known as Central Domain and the Central‐East Iranian Microcontinent [hereafter referred as CEIM]; Figure ) (Khodaverdian, Zafarani, & Rahimian, ; Nilforoushan et al, ; Vernant et al, ; Walpersdorf et al, ), in response to a geodynamic scenario dominated by ~N–S‐directed convergence since at least 52 Ma (Berberian, , ; Berberian & Yeats, ; Jackson, Haines, & Holt, ; McQuarrie et al, ; Nowroozi & Mohajer‐Ashjai, ; Walker & Jackson, ).…”

“…The Doruneh Fault (DF), also referred to as Great Kavir Fault (Javadi et al, ; Stöcklin & Nabavi, ; Tchalenko, Berberian, & Behzadi, ; Walker & Jackson, ), is commonly considered the northern mechanical boundary of the CEIM (e.g., Berberian, ; Farbod et al, ; Fattahi et al, ; Mattei et al, ; Walker & Jackson, ; Walpersdorf et al, ) (Figure ). Due to evidence indicating major kinematic shifts from dextral to sinistral shearing and changes in the regional state of stress during Late Cenozoic times, the DF region (Bagheri et al, ; Farbod et al, ; Javadi et al, , ; Tadayon et al, ) represents a key region to decipher the Cenozoic spatio‐temporal tectonic evolution of the CEIM. Paleotectonic reconstructions also outline the importance of the DF as a major transfer zone in the upper‐plate domain of the Neotethyan subduction (Barrier et al, ), which is held to be responsible for having accommodated the Mesozoic–Cenozoic rigid block rotation of the CEIM that may reconcile the post‐Cimmerian distribution of the Paleotethyan sutures in central and northeastern Iran (Alavi, Vaziri, Seyed‐Emami, & Lasemi, ; Bagheri & Stampfli, ; Mattei et al, ; Zanchi et al, ).…”