Timing of uplift in the Zagros belt/Iranian plateau and accommodation of late Cenozoic Arabia–Eurasia convergence

Abstract

-The motion of Arabia was stable with respect to Eurasia over the past 22 Ma. Deformation and exhumation in the Zagros is seen to initiate at the same time as argued by new detrital thermochronologic constraints and increasing accumulation rates in synorogenic sediments. A recent magnetostratigraphic dating of the Bakhtyari conglomerates in the northern Fars region of the Zagros further suggests that shortening and uplift in the Zagros Folded Belt accelerated after 12.4 Ma. Available temporal constraints from surrounding collision belts indicate that shortening and uplift focused in regions bordering the Iranian plateau to the south between 15 and 5 Ma. As boundary velocity was kept constant this requires concomitant decreasing strain rates in the Iranian plateau. Slab detachment has been proposed to explain the observed changes as well as mantle delamination, but the insignificant change in the Arabian slab motion and lack of unambiguous constraints make both hypotheses difficult to account for. It is proposed based on a review of shortening estimates provided throughout the Arabia-Eurasia collision that the total 440 km of convergence predicted by geodesy and plate reconstruction over the past 22 Ma can be accounted for by distributed shortening. I suggest that the topography and expansion of the Iranian plateau over Late Miocene-Pliocene time can be reproduced by the progressive thickening of the originally thin Iranian continental lithosphere presumably thermally weakened during the Eocene extensional and magmatic event.

Geochemical characteristics and conditions of formation of the Chah-Bazargan peraluminous granitic patches, ShahrBabak, Iran

“…Subduction and arc magmatism began in latest Triassic/Early Jurassic time, culminating at ~170 Ma (Hassanzadeh & Wernicke 2016). The final closure of the Neotethys and the collision of the Arabian and Eurasian plates took place during the Tertiary period Alavi 1994;Golonka 2004;Molinaro et al 2005;Omrani et al 2008;Agard et al 2011;Mouthereau 2011;Yousefirad 2011;Khadivi et al 2012;Mouthereau et al 2012;Mohajjel & Fergusson 2014;Sheikholeslami 2015). Based on Hassanzadeh & Wernicke (2016) the collision took place during the mid-Tertiary.…”

“…Based on Hassanzadeh & Wernicke (2016) the collision took place during the mid-Tertiary. During the same period, the Zagros Fold-Thrust Belt formed as part of the Alpine-Himalayan mountain chain, extending about 2000 km from eastern Turkey to the Oman line in southern Iran (Berberian & King 1981;Alavi 1994;Agard et al 2005;Omrani et al 2008;Agard et al 2011;Mouthereau 2011;Mouthereau et al 2012;Mohajjel & Fergusson 2014;Sheikholeslami 2015). The Chah-Bazargan intrusion is located in northeast Neyriz which is a part of the south Sanandaj-Sirjan zone.…”

Kinematics of Post-obduction Deformation of the Tertiary Ridge at Al-Khod Village (Muscat, Oman)

“…The onset of the deformation of the Zagros Mountain Belt dates with 22 Ma and the convergence since that time amounts to 440 km [12].…”

Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?

“…1). NeoTethys subduction below the Iran margin started at least in Jurassic time and continued until Arabia-Eurasia collision in latest Eocene-Early Oligocene time (Agard et al, 2011;Mouthereau, 2011;McQuarrie and van Hinsbergen, 2013). Subduction below Tibet in the Early Cretaceous occurred simultaneously with Indian separation from eastern Antarctica and Australia ∼ 130 Ma ago (Guillot et al, 2008;van Hinsbergen et al, 2011a).…”

“…We used the reconstructed position of three points located on the western, central and eastern syntaxis of each plate, similar to Rosenbaum and Lister (2002), Alvarez (2010) and van Hinsbergen et al (2011a van Hinsbergen et al (2011a). Because Cretaceous-Cenozoic intra-Eurasian shortening north of the African-Arabian plate is limited to perhaps 200 km and focused in the late Cenozoic (e.g., Mouthereau, 2011;McQuarrie and van Hinsbergen, 2013), we considered Africa/Arabia-Eurasia convergence rates as subduction rates. For India, the subduction rate was calculated subtracting intra-Asian shortening rates expressed as Euler rotation parameters by van Hinsbergen et al (2011b) from India-Asia convergence rates.…”