Eocene Kashmar granitoids (NE Iran): Petrogenetic constraints from U–Pb zircon geochronology and isotope geochemistry

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

“…These deposits caused the resetting of the AFT and AHe thermochonological systems in most samples. To the east, this period corresponds to the genesis of KAIC that intrudes these volcano‐clastic succession (Shafaii Moghadam et al, ), providing a further support to the relevant thickness of the host units.…”

“…The AFT and AHe frequency age distribution plots (for the data compilation and processing refer to Data S1) allow to appreciate the regional spatio‐temporal distribution of the main exhumation phases in Iran and to draw inferences on their generating tectonic processes (Figure ). The main regional events considered herein are (a) the Cretaceous–Palaeocene contractional regime resulting in obduction of Zagros ophiolites and closure of the Nain–Baft and Sabzevar back‐arc oceans in the upper‐plate of the Neotethyan subduction (Agard et al, , ; Mouthereau et al, ; Rossetti et al, ; Rossetti et al, ; Shafaii Moghadam et al, ; Shafaii Moghadam & Stern, ); (b) the Palaeocene–Eocene rift‐related subsidence and magmatic flare‐up, associated with core‐complex formation in Central Iran (Agard et al, , ; Chiu et al, ; Kargaranbafghi et al, ; Shafaii Moghadam et al, , ; Verdel et al, ; 2011; Vincent et al, ); (c) the initiation of continental collision at the plate boundary, commonly placed in the Late Eocene–Oligocene times (Allen & Armstrong, ; Berberian & Berberian, ; Berberian & King, ; François et al, ; Hafkenscheid et al, ; Hessami et al, ; Homke et al, , ; Horton et al, ; Kargaranbafghi et al, ; Madanipour et al, ; McQuarrie et al, ; Mouthereau et al, ; Robertson et al, ; Tadayon et al, ; Vincent et al, ); (4) the early Miocene “hard collision” stage (Allen et al, ; Axen et al, ; Ballato et al, , , ; Calzolari, Rossetti, et al, ; François et al, ; Gavillot et al, ; Guest, Stockli, et al, ; Hessami et al, ; Homke et al, ; Khadivi et al, , ; Madanipour et al, , ; Morley et al, ; Mouthereau et al, ; Okay et al, ; Rezaeian et al, ); and (5) the Late Miocene‐early Pliocene regional tectonic reorganization (Axen et al, …”

“…Such domains presently form the various ophiolitic sutures zones that surround the CEIM (Figure ). Available geochronological data frame the oceanic crust generation and destruction in the back‐arc domain during the Cretaceous–Palaeocene times (Bröcker et al, ; Rossetti et al, , ; Shafaii Moghadam et al, ; Shafaii Moghadam et al, , ; Zarrinkoub et al, ). Furthermore, a period of Cretaceous to Palaeocene contraction is regionally documented by field evidence (Berberian & Berberian, ; Berberian & King, ; Şengör, ; Stocklin, ) and supported by thermochronological results (Kargaranbafghi, Neubauer, & Genser, ; Verdel et al, ).…”

“…This Palaeocene–Eocene succession is dominantly exposed in the NW sector of the study area, where it shows a maximum thickness of approximately 5 km (Figure ). To the east, it is intruded by the middle Eocene calcalkaline Kashmar granitoids (Shafaii Moghadam et al, ; Soltani, ; Taheri et al, ), which define a approximately 100‐km long magmatic belt (hereafter referred to as Kashmar–Azghand Intrusive complex, KAIC) to the north of the Kashmar and Azghand cities (Figure ). The U–Pb zircon dating of the southern rim of the KAIC provided a middle Eocene (40–41 Ma) formation age for the Kashmar granitoids (Shafaii Moghadam et al, ).…”

“…To the east, it is intruded by the middle Eocene calcalkaline Kashmar granitoids (Shafaii Moghadam et al, ; Soltani, ; Taheri et al, ), which define a approximately 100‐km long magmatic belt (hereafter referred to as Kashmar–Azghand Intrusive complex, KAIC) to the north of the Kashmar and Azghand cities (Figure ). The U–Pb zircon dating of the southern rim of the KAIC provided a middle Eocene (40–41 Ma) formation age for the Kashmar granitoids (Shafaii Moghadam et al, ). It is worth noting that the Palaeocene–Eocene strata also unconformably cover the folded and sheared ophiolite units (Figures a‐b).…”