Overview of the tectonic evolution of the Iraqi Zagros thrust zone: Sixty million years of Neotethyan ocean subduction

Detrital zircon provenance record of the Zagros mountain building from the Neotethys obduction to the Arabia-Eurasia collision, NW Zagros fold-thrust belt, Kurdistan region of Iraq

“…8). Along-strike, both groups show older ages toward SE, similar to the age trend of the Walash and Naopurdan rocks, ~24-33 Ma in the NW and ~32-43 Ma in the SE (Ali et al, 2019). 315 So far in the vicinity of the study area, the late Oligocene magmatism has been documented only in two localities in the northwestern Zagros, including the Kurdistan region of Iraq and Iran (Ali et al, 2013;Whitechurch et al, 2013), but further NW in Iran magmatism is more abundant (Agard et al, 2011;Chiu et al, 2013).…”

“…Along strike farther to the southeast, an angular unconformity between the Red Beds Series (Suwais Group) and the Lower Cretaceous 160 Qulqula radiolarites is also preserved (Karim et al, 2011). Structurally, the highest unit is the Qandeel Series, which is an ophiolite-bearing Upper Cretaceous metamorphosed klippe that likely disjointed by an out-of-sequence deformation from the adjacent terranes of the Sanandaj-Sirjan zone (SSZ) Ali et al, 2014;Ali et al, 2019). The Walash Group (Fig.…”

“…The signature of the Paleocene magmatism is also reflected in the detrital zircon U-Pb and (U-Th)/He record of the Red Beds Series that derived from the WNK complex. The locality of this arc system is contested as it is not clear whether it developed in the vicinity of the Eurasian plate (Agard et al, 2005;Al-Qayim et al, 2012;Whitechurch et al, 2013) or close to the Arabian plate (Aswad et al, 2014;Ali et al, 2017Ali et al, , 2019. However, due to presence of Eurasian derived detritus (Homke et al, 2010;Whitechurch et al, 2013) and the occurrence of low-grade metamorphic grains (Ali et 395 al., 2017), which are abundant in the Sanandaj-Sirjan zone (SSZ) (Hassanzadeh and Vernicke, 2016), a Eurasian-related setting that resulted from the oceanic slab rollback is more likely (Whitechurch et al, 2013).…”

“…For this period, the Eocene, several models suggested multiple subduction zones with 200-300 km distance between 410 the zones across the Neotethys to explain the documented magmatic activities (Aswad et al, 2016;Ali et al, 2017;Ali et al, 2019). However, due to space problems and difficulties of subduction inception a multiple subduction system has been considered as unlikely (Whitechurch et al, 2013).…”

U–Pbage,Hf–Oisotopes, and geochemistry ofthe Sardasht ophiolite in the NWZagros orogen: Implications for the tectonic evolution ofNeo‐Tethys

“…However, recent studies show that the gabbros and plagiogranites of the Kermanshah ophiolite have a zircon age of 36-39 Ma (Ao et al, 2016) and sub-alkaline basalts in the Walsh area in nearby Iraq have an Eocene period (Ali et al, 2013;Ali, Sleabi, Talabani, & Jones, 2017).The tectonic evolution of the Neo-Tethyan Ocean was more complicated in the NW Zagros and is still poorly understood (Alavi, 1994;Ali, Nutman, Aswad, & Jones, 2019;Ao et al, 2016;Hassanzadeh & Wernicke, 2016;Moghadam & Stern, 2011). In particular, some crucial ophiolites in NW Zagros along the boundary of Iran and Iraq generally lack isotopic ages, and yet they should provide critical information about the history of ophiolite formation and accretion.…”