Zagros orogeny: a subduction-dominated process

Abstract

-This paper presents a synthetic view of the geodynamic evolution of the Zagros orogen within the frame of the Arabia-Eurasia collision. The Zagros orogen and the Iranian plateau preserve a record of the long-standing convergence history between Eurasia and Arabia across the Neo-Tethys, from subduction/obduction processes to present-day collision (from ∼ 150 to 0 Ma). We herein combine the results obtained on several geodynamic issues, namely the location of the oceanic suture zone, the age of oceanic closure and collision, the magmatic and geochemical evolution of the Eurasian upper plate during convergence (as testified by the successive Sanandaj-Sirjan, Kermanshah and Urumieh-Dokhtar magmatic arcs), the P-T-t history of the few Zagros blueschists, the convergence characteristics across the Neo-Tethys (kinematic velocities, tomographic constraints, subduction zones and obduction processes), together with a survey of recent results gathered by others. We provide lithospheric-scale reconstructions of the Zagros orogen from ∼ 150 to 0 Ma across two SW-NE transects. The evolution of the Zagros orogen is also compared to those of the nearby Turkish and Himalayan orogens. In our geotectonic scenario for the Zagros convergence, we outline three main periods/regimes: (1) the Mid to Late Cretaceous (115-85 Ma) corresponds to a distinctive period of perturbation of subduction processes and interplate mechanical coupling marked by blueschist exhumation and upper-plate fragmentation, (2) the Paleocene-Eocene (60-40 Ma) witnesses slab break-off, major shifts in arc magmatism and distributed extension within the upper plate, and (3) from the Oligocene onwards (∼ 30-0 Ma), collision develops with a progressive SW migration of deformation and topographic build-up (Sanandaj-Sirjan Zone: 20-15 Ma, High Zagros: ∼ 12-8 Ma; Simply Folded Belt: 5-0 Ma) and with partial slab tear at depths (∼ 10 Ma to present). Our reconstructions underline the key role played by subduction throughout the whole convergence history. We finally stress that such a long-lasting subduction system with changing boundary conditions also makes the Zagros orogen an ideal natural laboratory for subduction processes.

Improving Lithological Mapping by SVM Classification of Spectral and Morphological Features: The Discovery of a New Chromite Body in the Mawat Ophiolite Complex (Kurdistan, NE Iraq)

“…This belt is around 2000 km long, extending from SE Turkey through Iraq to southern Iran [35][36][37][38]. The Iraqi part of the Zagros orogenic belt consists of three main tectonic zones: (1) the Inner Platform (stable shelf); (2) the Outer Platform (unstable shelf), which comprises the Mesopotamia Foredeep, the Foothill Zone, the High Folded Zone, and the Imbricated Zone (IZ); and (3) the Zagros Suture Zone (ZSZ) ( [9,30,36,39,40]; Figure 1). Most of the study area lies within the ZSZ, represented by the Penjween-Walash Zone (PWZ), the Qulqula-Khwarkurk Zone (QKZ), and a small part of the Arabian Outer Platform (unstable shelf) represented by the IZ (Figure 1).…”

Geochemical and isotopic evidence for Carboniferous rifting: mafic dykes in the central Sanandaj-Sirjan zone (Dorud-Azna, West Iran)

“…The Zagros orogenic belt resulted from the collision of the African -Arabian continent and the Iranian microcontinent (Berberian & King 1981;Alavi 1994;Mohajjel & Fergusson 2000;Agard et al 2005Agard et al , 2011Hafkenscheid et al 2006). The Dorud-Azna region is situated in the central part of the SSZ close to the Main Zagros thrust.…”

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

“…Therefore, the tectonic regime between the Arabian margin and Sanandaj-Sirjan plate altered from passive to convergent (Ricou 1994). During the Mesozoic, the oceanic crust of the Neotethys was subducted beneath the Eurasian plate (Golonka 2004;Molinaro et al 2005;Agard et al 2011;Yousefirad 2011;Mouthereau et al 2012;Karimi et al 2012;Mohajjel & Fergusson 2014;Sheikholeslami 2015), and the Sanandaj-Sirjan zone occupied the position of a magmatic arc Agard et al 2005;Agard et al 2011;Karimi et al 2012;Mouthereau et al 2012;Chiu et al 2013;Mohajjel & Fergusson 2014;Akbari et al 2016;Hassanzadeh & Wernicke 2016). Subduction and arc magmatism began in latest Triassic/Early Jurassic time, culminating at ~170 Ma (Hassanzadeh & Wernicke 2016).…”

“…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.…”