Tectonic evolution of the Zagros Orogen in the realm of the Neotethys between the Central Iran and Arabian Plates: An ophiolite perspective

The Zagros Orogenic Belt includes the Fold and Thrust Belt, the High Zagros Belt, the Outer Zagros Ophiolitic Belt, the Sanandaj–Sirjan Metamorphic Belt, the Inner Zagros Ophiolitic Belt, and the Urumieh– Dokhtar Magmatic Belt. We divide the High Zagros evolutionary history into five stages: (1) triple junction formation, (2) continental lithosphere rifting, (3) generation, spreading, and maturation of the Neotethys Ocean, (4) subduction of the oceanic lithosphere, and (5) collision. The Neotethys triple junction, located at the southeastern corner of the Arabian Plate, formed during the Late Silurian–Early Carboniferous. Subsequently, this triple junction became a rift basin due to normal faulting and basalt eruption. The rifting stage occurred during the Late Carboniferous–Early Permian. Thereafter, extension of the basin continued, leading to spreading and maturation of the Neotethys oceanic basin during the Late Permian–Late Triassic. Probably at the end of the Late Triassic, closure of the Paleotethys Basin caused the initiation of two northeastward subductions: (1) oceanic–oceanic and (2) oceanic–continental. Oceanic–oceanic subduction continued until the Late Cretaceous and was terminated by the emplacement of the Outer Zagros Ophiolites, whereas oceanic–continental subduction continued until the Middle Miocene. Subduction in the southern Neotethys Basin between the Arabian and Central Iran Plates caused a tensional regime between Sanandaj– Sirjan and Central Iran, and the formation of a back-arc basin that by its closing led to the emplacement of the Inner Zagros Ophiolites during the Late Cretaceous.


Introduction
The Alpine-Himalayan Orogenic Belt consists of two branches in Iran, the Alborz Mountains with an E-W trend and the Zagros Orogen with an NW-SE trend (Alavi 1994;Agard et al. 2005).The Zagros Orogen extends from eastern Turkey through northern Iraq and northwest of Iran to the Hormuz Strait and Oman (Alavi 1994;McQuarrie 2004;Agard et al. 2005;Homke et al. 2010).Because of the key situation of the Zagros Orogen within the Alpine-Himalayan Orogenic Belt and its importance in revealing the nature of Neotethys Ocean evolution and closure, numerous studies have been carried out on its magmatic, sedimentary, metamorphic, and structural characteristics (e.g., Takin 1972;Stöcklin 1977;Berberian and King 1981;Şengör 1984;Dercourt et al. 1986;Şengör et al. 1988;Glennie 1992;Alavi 1994;Stampfli and Borel 2002;Mohajjel et al. 2003;Golonka 2004;Shahabpour 2005;Agard et al. 2005;Kazmin and Tikhonova 2006;Robertson 2007;Sheikholeslami et al. 2008;De Vera et al. 2009;Allahyari et al. 2010;Homke et al. 2010;Saura et al. 2011;Ghazi et al. 2012;Saccani et al. 2013;Chiu et al. 2013;McQuarrie and van Hinsbergen 2013, among many others).On the basis of tectonomagmatic and structural features, the Zagros Orogen is subdivided into nine subzones (Falcon 1969;Berberian 1995;Emami et al. 2010;Homke et al. 2010), which are the Mesopotamian-Persian Gulf Foreland, the Dezful Embayment, the Fold and Thrust Belt, the Crush Zone (High Zagros or Imbricated Zone), the Outer Zagros Ophiolite Belt, the Sanandaj-Sirjan First Metamorphic Belt, the Mesozoic Magmatic Belt, the Sanandaj-Sirjan Second Metamorphic Belt, and the Urumieh-Dokhtar Magmatic Belt (UDMB) (Fig. 1).The formation of the Zagros Basin is related to the rifting and separation of Central Iran from the northern margin of Gondwana, which formed the Neotethys Basin (Agard et al. 2005;Yousefirad 2011;Chiu et al. 2013).Closure of the Neotethys Ocean and the collision between the Central Iran and Arabian Plates formed the Zagros Orogen (Yousefirad 2011;Chiu et al. 2013).To reconstruct the Zagros Orogen evolution, several models have been presented, but none can explain all of its geologic aspects completely.In this contribution, we try to present a comprehensive reconstruction model for the Zagros Orogen to better explain its characteristics, by reviewing and discussing all hypotheses.

Geologic context
The Zagros Orogen is a result of the closure of the southern Neotethys, located between the Iranian and Arabian Plates (Alavi 1994;Talbot and Alavi 1996;Stampfli and Borel 2002;Casini et al. 2011).Ophiolites, which are Neotethys oceanic lithosphere remnants, are emplaced along the Zagros Orogen.These ophiolites are emplaced along two main belts (Figs 1 and 2; Stöcklin 1977;Homke et al. 2010;Ghazi et al. 2012).The first one is the Khoy-Nain-Shahr Babak-Dehshir-Baft Ophiolitic Belt (Inner Zagros Ophiolitic Belt or IZOB; Shafaii Moghadam and Stern 2 Ajirlu et al.  2011), located between the Sanandaj-Sirjan and Central Iran; the second one is the main ophiolitic belt of Piranshahr-Kermanshah-Neyriz-Haji-Abad [Outer Zagros Ophiolitic Belt (OZOB); Shafaii Moghadam and Stern 2011], located between the Sanandaj-Sirjan and Zagros (Fig. 1).The IZOB resulted from the closure of the southern Neotethys Basin, while the OZOB resulted from the closure of the Neotethyan back-arc basin (Alavi 1994;Ghasemi and Talbot 2006;Allahyari et al. 2010;Casini et al. 2011;Ghazi et al. 2012;Saccani et al. 2013).In a schematic cross-section across the Zagros Orogen, the main structural elements are shown.These structures are cover sediments, the Cenozoic Magmatic Belt, the Inner Ophiolite Belt, the Second Metamorphic Belt, the Mesozoic Magmatic Belt, the First Metamorphic Belt, the Outer Ophiolite Belt, the Crush Zone, the Fold and Thrust Belt, the Dezful Embayment, and the Persian Gulf-Mesopotamian Foreland (Fig. 2).In the following, we will explain why it is necessary to divide the Sanandaj-Sirjan metamorphic zone into two subzones (the First Metamorphic Belt and the Second Metamorphic Belt).

The Outer Zagros Ophiolitic Belt (OZOB)
The OZOB crops out along the southern Neotethys suture.The OZOB, which includes the Piranshahr, Kermanshah, Neyriz, and Haji-Abad Ophiolites, is the result of the Late Cretaceous closure and collision between the Sanandaj-Sirjan and the Arabian Shield (Fig. 1).Stratigraphic columns for these ophiolites are shown in Fig. 4.

The Kermanshah Ophiolite
The Kermanshah ophiolitic complex, located along the main Zagros reverse fault, is an ophiolitic mélange, which includes dismembered ophiolitic sequences.The mantle sequence predominately includes lherzolite, dunite, and harzburgite, and its crustal sequence includes cumulative gabbro, sheeted dikes, pillow lavas, and diorites, and a volcanic sequence that ranges in composition from sub-alkaline basalt through alkaline basalt to trachyte (Fig. 4).Ghazi and Hassanipak (1999) recognized both island-arc tholeiitic and alkaline lavas.Tholeiitic basalt is a normal mid-ocean ridge to enriched mid-ocean ridge basalt (Allahyari et al. 2010).The E-MORB characteristics of middle ocean ridge basalt and the lherzolite composition of peridotite indicate that partial melting and the sea-floor spreading rate was low.Ghazi and Hassanipak (1999), using geochemical data, clearly distinguished two distinct types of sub-alkaline basalt, suggesting an island-arc affinity, as well as alkaline basalt, suggesting a typical oceanic island.During the Maastrichtian, the Kermanshah Ophiolite was thrusted into the Lower Triassic-Upper Cretaceous Bisoton limestone (Lippard et al. 1986;Berberian 1995;Ghasemi and Talbot 2006).The Amiran Formation conglomerate of Maastrichtian-Paleocene age contains ophiolite clasts.Subsequently, the initial thrusting of the Kermanshah Ophiolite occurred during Maastrichtian-Paleocene time (Alavi 1994;Hooper et al. 1995;Ghasemi and Talbot 2006).The Paleocene volcanic rocks and Eocene shallow-water limestone unconformably cover the Kermanshah Ophiolite (Braud 1987;Ghasemi and Talbot 2006).

The Haji-Abad Ophiolites
The Haji-Abad (or Esfandagheh) Ophiolite, as a part of the OZOB, is located in the northwest of the town of Esfandagheh.The Haji-Abad Ophiolite mantle sequence 10 Ajirlu et al.

Evolution of the ophiolite suites
Using the spatial distribution of the major ophiolitic complexes of the Zagros Orogen and other features, we describe the tectonomagmatic and tectonostratigraphic evolution of this Orogen in five stages: (1) triple junction formation, (2) continental lithosphere rifting, (3) generation, spreading, and maturation of the Neotethys Ocean, (4) subduction of the oceanic lithosphere, and (5) collision.

Triple junction formation stage (Late Silurian-Early Carboniferous)
The formation of the Neotethyan triple junction began when a thermal bulge (plume) formed in the Gondwana continent through hot spots (Lapierre et al. 2004;Chauvet et al. 2009Chauvet et al. , 2011;;Saccani et al. 2013).This plume rose toward the upper levels and lower depths of the mantle.By underplating beneath the Gondwana lithosphere, this lithosphere thinned and swelled (Fig. 6).Thereafter, by initiation of three radial fractures, three arms of the Neotethys Basin formed (Numan 2001;Lapierre et al. 2004;Chauvet et al. 2009).The joining of these three arms formed the Neotethys triple junction.This triple junction is located at the southeast corner of the Arabian Plate (Lapierre et al. 2004;Jassim and Goff 2006;Chauvet et al. 2009Chauvet et al. , 2011;;Saccani et al. 2013).Extension into the continental lithosphere occurred by normal faulting.In many references, the rifting time of Neotethys is stated as Early Permian (e.g., Dercourt et al. 1986;Şengör et al. 1988;Glennie 1992;Ziegler 2001;Stampfli and Borel 2002;Shahabpour 2005;Almutury and Al-Asadi 2008;Muttoni et al. 2009;Allahyari et al. 2010;Homke et al. 2010;Saccani et al. 2013).However, comparing the lithostratigraphic columns of the ZOB and the Arabia (Fig. 5), it can be observed that from the Pre-Cambrian to the Late Ordovician, the two blocks of the Central Iran and Arabian Plates together formed a stable shield (Fig. 6; Gondwana Shield).In the Early Silurian (Caledonian Orogeny), this shield was divided into two segments of the Central Iran and Arabian Plates (Fig. 6).The uprising magmatic plumes and their under-plating caused swelling and bulging of the lithosphere (Fig. 7; Lapierre et al. 2004;Chauvet et al. 2009Chauvet et al. , 2011)).Subsequently, this swelling led to the termination of sedimentation and oceanic regression.Therefore, the lack of Ordovician and Silurian to Carboniferous strata along the Central Zagros and the existence of terrigenous sediments (Sare-Chahan and Zakeen Formations) in the Zagros Crush Zone indicate that during this time, the Neotethys plume was emplaced beneath the lithosphere of Gondwana and led to epeirogeny between the Central Iran and Arabian Plates (Fig. 5).

Continental rifting stage (Late Carboniferous-Early Permian)
From the Late Silurian to the Early Carboniferous, the three arms of the Neotethys and its triple junction were probably formed (triple junction formation stage); then, by the eruption of plume magmas, the alkaline basalt of Dehbid and other extrusive rocks were generated (Fig. 6; Ghasemi and Talbot 2006).Magma eruption may have occurred during the Carboniferous and have led to subsidence along normal faults.This subsidence also created a shallow-water sedimentary basin.This basin is determined by the deposition of evaporates and terrigenous sediments (Faraghan and Dalan Formations).With continuing activity of normal faults, depth increased and the Neotethys Basin was formed (Almutury and Al-Asadi 2008).During the early stages of rifting, the basin was almost dry or contained fresh-water lakes (Fig. 7; Almutury and Al-Asadi 2008).Eventually, the floor of the Neotethys rift subsided and formed a shallow sea.This subsidence and spreading occurred from the Late Carboniferous to Liassic time (Koop and Stoneley 1982;Shahabpour 2005;Sheikholeslami et al. 2008;Homke et al. 2010;Emami et al. 2010;Saccani et al. 2013).Continental sediments accumulated in the depressions of the down-faulted blocks, and basaltic magma was injected into the rift system (Fig. 7; Almutury and Al-Asadi 2008).Flood basalt could have extended over large areas of the rift zone during this phase (Van der Pluijm and Marshak 1997; Ghasemi and Talbot 2006).Subsidence of the basin floor led to the formation of a passive margin along the northern and southern margins of the Arabian Plate (Figs 6-9;Koop and Stoneley 1982;Agard et al. 2005;Jassim and Goff 2006;Arfania and Shahriari 2009).During the Late Permian to Late Triassic, the deep-water continental slope was formed along the northwestern and northeastern margins of the Arabian Plate (Fig. 6; Faugères and Pujol 1991;Shahabpour 2005;Ghasemi and Talbot 2006;Allahyari et al. 2010;Yousefirad 2011;Saccani et al. 2013).
Due to the shallow nature of the basin during the rifting stages, evaporation was considerable; salt and sandstone was deposited on the floor of the rift as the Faraghan and Dalan Formations (Fig. 7).Thick salt and sandstone deposits of these formations lie at the base of the passive margin basin (Figs 5 and 6).At the center of the basin, where it was deeper and wider, limestone of Khaneh Kat Formation was deposited (Figs 5 and 6).The spreading stage was terminated by the beginning of subduction related to the closure of the Paleotethys Basin in the northern Iran in the Late Triassic (Fig. 7).
Subduction of the oceanic lithosphere stage (Triassic-Late Cretaceous) At this stage, the Neotethys Basin, on account of the Arabian Plate movements caused by the opening of the Atlantic Ocean rift (Stampfli 2000;Bird et al. 2007), changed the divergence régime to one of the convergence (Fig. 6).The observed absence of sedimentation from Late Triassic to Lower Early Jurassic (Fig. 5) was a result of the closure of a Paleotethys Basin branch along North Iran (Berberian and King 1981;Bagheri and Stampfli 2008;Zanchi et al. 2009;Buchs et al. 2013).From the Late Permian to the Late Triassic, forces from the spreading of the Neotethys mid-ocean ridge caused the subduction of the Paleotethys oceanic lithosphere; following closure of the Paleotethys Ocean in the Late Triassic, tectonic forces caused epeirogeny in the Neotethys Basin.Then, during the Upper Late Triassic to the beginning of the Lower Jurassic, the high slab pushing forces of the Neotethys mid-ocean ridge caused a break in the Neotethyan oceanic lithosphere, which led to the onset of the subduction in the lower Early Jurassic (Figs 7-9).New studies by Chiu et al. (2013), which indicate a Middle Jurassic age for the oldest magmatic arc rocks of the SSMB and the UDMB, confirm this.The subduction led to the transformation of two passive margins into a passive margin and an active margin.The subduction of the Neotethys oceanic lithosphere beneath the Iranian and Anatolian continental lithosphere (McQuarrie and van Hinsbergen 2013) led to the eruption of magmas formed as volcanic arcs (Figs 7-9;Alavi 1994;Shahabpour 2007;Chiu et al. 2013).Likewise, it led to the formation of the Neotethyan back-arc rift in the Middle Jurassic age (Figs 6-9;Azizi et al. 2006;Ghasemi and Talbot 2006;Shafaii Moghadam et al. 2009;Ghazi et al. 2012).
The subduction period extended from the Upper Early Jurassic age to the Lower Miocene age (Mohajjel et al. 2003;Golonka 2004;Yousefirad 2011;Ghazi et al. 2012;Chiu et al. 2013).Therefore, the UDMB, with a Middle Jurassic age to Late Miocene age, can be considered as a volcanic arc of the Neotethys subduction system (Figs 7-9; Berberian and Berberian 1981;Berberian and King 1981;Berberian et al. 1982;Alavi 1994;Shahabpour 2007;Chiu et al. 2013).The UDMB consists predominately of intrusive and extrusive calc-alkaline igneous rocks and a low volume of shoshonitic and alkaline rocks (Chiu et al. 2013).The subduction of the Neotethys oceanic lithosphere created a tensional back-arc basin (Fig. 6; Kazmin and Tikhonova 2006;Azizi et al. 2006).The Khoy, Nain, Shahr Babak, Dehshir, and Baft Ophiolites mark the site of the Nain-Shahr Babak-Dehshir-Baft and of the Khoy Back-arc Basins, which opened between the SSMB and Central Iran (Fig. 6).Ghasemi and Talbot (2006) proposed an Upper Triassic-Lower Cretaceous age for the formation of the back-arc basin, whereas Ghazi et al. (2012) suggest an Early Jurassic time for its opening.Given that these ophiolites and their related igneous rocks have back-arc 18 Ajirlu et al. Central European Geology 59, 2016 (I-type, 176-144 Ma), (2) Late Cretaceous (72-81 Ma), (3) Early Eocene to Late Oligocene (25-55 Ma), (4) Early to Late Miocene , and (5) Late Miocene to Late Pliocene (11-0.4Ma) magmatism.The first episode was the result of two subductions, one is oceanic-oceanic and the other oceanic-continental, whereas the second and third episodes were the results of collision and continuing subduction.
The fourth episode represents the termination of the subduction-related magmatic activities, which ceased progressively from northwest to southeast, with magmatic activities ending in the Early Miocene (ca.22 Ma) in Meghri (Armenia), the Middle Miocene (ca.16 Ma) in Kashan, and the Late Miocene (ca.10-6 Ma) in Anar, respectively.The fifth episode indicates post-collisional volcanism that began ca.11 Ma in the Saray (eastern side of Lake Urmia), along with later eruptions in the Sahand (6.5-4.2Ma) and the Sabalan (≤0.4 Ma) volcanoes (Chiu et al. 2013).Based on the mentioned ages and episodes, two main magmatic gaps (between the Late Jurassic to Late Cretaceous and the Late Cretaceous to Early Eocene - Azizi and Moinevaziri 2009;Chiu et al. 2013) can be distinguished, which probably resulted from subduction of a cold oceanic lithosphere and/or low-angle subduction (Chiu et al. 2013).

Collision stage (Late Cretaceous-Late Miocene)
At this stage, the Neotethys oceanic lithosphere was totally consumed.Following this, passive continental margin and island-arc collision occurred in the Late Cretaceous (Golonka 2004;Kazmin and Tikhonova 2006;Allahyari et al. 2010;Saccani et al. 2013).This collision caused obduction of the Neotethys oceanic lithosphere remnants into the Arabian Plate margin, but in the Zagros Crush Zone, there remained a shallowwater oceanic basin, where Upper Cretaceous limestone was deposited (Fig. 5; Alavi 1994;Ricou 1974;Haynes and McQuillan 1974;Babaei et al. 2005;Ghasemi and Talbot 2006;Yousefirad 2011).Erosion of continental collisional highs carried an enormous volume of detrital materials into the remaining shallow-water basin of the Neotethys.The Amiran Formation was formed in this way (Fig. 5;Braud 1987;Ghasemi and Talbot 2006;Yousefirad 2011).The foreland basin formed following the collision is the Mesopotamian-Persian Gulf of NW-SE trend; the hinterland basins are the depressions that are usually located between Zagros and Central Iran (Fig. 1; Homke et al., 2010;Emami et al. 2010;Saura et al. 2011).After the closure of the oceanic lithosphere between the Arabian Plate margin and the Neotethys island arcs, and the emplacement of the Outer Zagros Ophiolites, the subduction of Neotethys oceanic lithosphere between the island arcs and the Sanandaj-Sirjan Zone continued until the Late Miocene (Figs 6-9).Based on the southern Neotethys Basin structural elements that include Foreland Basin Sediments, Fold and Thrust Belt, Crush Zone, ophiolite remnants, the First Metamorphic Belt, island-arc magmatic rocks, the Second Metamorphic Belt, and the magmatic belt (Fig. 1), two subduction systems and two collisions can be considered for evolution of the Tethysides along the Zagros Orogen.The beginning of both subductions occurred in the Upper Late Triassic, but collision occurred at different times.
20 Ajirlu et al. Central European Geology 59, 2016 The first collision was due to the closure of the basin between the passive continental margin and the forearc in the Late Cretaceous; the second collision was caused by basin closure between the back-arc and the active continental margin, which occurred in the Late Miocene .A large amount of evidence indicates that the first collision occurred in the Upper Cretaceous.The Neyriz Ophiolite is unconformably covered by the Late Cretaceous anhydritic limestone of the Tarbur Formation (Fig. 4; Ricou 1968Ricou , 1974)).The Amiran Formation conglomerates of Maastrichtian-Paleocene age (Fig. 5) have ophiolite clasts, showing that the emplacement time of these ophiolites is pre-Maastrichtian.Paleocene volcanism and Eocene shallow-water limestone deposition unconformably cover the Kermanshah Ophiolite (Braud 1987;Ghasemi and Talbot 2006).The Haji-Abad Ophiolite is overlain by Upper Cretaceous pelagic limestone.Based on 40 Ar/ 39 Ar dating, the Neyriz Ophiolite complex formed at 96-98 Ma (Haynes and Reynolds 1980) and was emplaced at 89 Ma (Lanphere and Pamić 1983;Ghasemi and Talbot 2006).The Nain-Shahr Babak-Dehshir-Baft Ophiolites are also covered by Coniacian-Maastrichtian pelagic limestone (Babaei et al. 2005;Ghasemi and Talbot 2006;Shafaii Moghadam and Stern 2011).Therefore, the presence of an Upper Cretaceous unconformity, coverage by Upper Cretaceous limestone and volcanic rocks, and ophiolitic clasts in the Amiran conglomerate all indicate that in the Upper Cretaceous, the Neotethys Back-arc Basin between the Central Iran and Sanandaj-Sirjan was closed, and likewise that the oceanic-oceanic subduction of the southern Neotethys Basin was terminated .The ophiolite remnants obducted onto the Arabian Plate margin and Sanandaj-Sirjan, and the Inner and Outer ophiolites were emplaced.By emplacement of these ophiolites, a foreland basin was formed in front of the outer ophiolitic belt; ophiolite-radiolarite provided the detritic materials supplying the Upper Maastrichtian-Paleocene Amiran flysch deposit (Berberian and King 1981;Alavi 1994;Hooper et al. 1995;Homke et al. 2010).The Upper Maastrichtian-Paleocene Amiran flysch accumulated along a linear trough in the High Zagros area.
The final closure of Neotethys and the collision between the Arabian and Central Iran Plates took place in the Cenozoic.Agard et al. (2005) suggested the Late Oligocene for collision between Iranian and Arabian margins, whereas Navabpour et al. (2007) believe that collision occurred between 20 and 10 Ma age (Late to Middle Miocene).Chiu et al. (2013), based on the termination of calc-alkaline magmatism in the UDMB, showed that the collision age is Early to Late Miocene.This timing is consistent with the geologic evidence of the final closure of the Neotethys Ocean between Arabia and Eurasia at ∼20 Ma in the Bitlis Suture Zone, to the NW of the Zagros (Okay et al. 2010).

Conclusions
The purpose of this contribution is to present a comprehensive reconstruction model for the evolutionary history of the Zagros Orogen that justifies most petrologic, Tectonic evolution of the Zagros Orogen 21 Central European Geology 59, 2016 tectonomagmatic, and stratigraphic characteristics.The formation of the Neotethyan triple junction began during the Late Silurian to Early Carboniferous.One of the three arms of the triple junction subsided, and began spreading, which resulted in a shallowwater basin during the Late Carboniferous-Early Permian.Subsiding and spreading continued from the Late Carboniferous to the Late Triassic.In the Late Triassic, the Neotethys Basin reached its maximum extension.From the Late Permian to the Late Triassic, the force of the Neotethys mid-ocean ridge spreading was consumed by subduction of the Paleotethys oceanic lithosphere.After the closure of the Paleotethys Ocean during the Late Triassic, tectonic forces caused epeirogeny in the Neotethys Basin that eventually led to the simultaneous initiation of two northeastward subductions during Upper Late Triassic.Oceanic-oceanic subduction continued until the Late Cretaceous and was terminated at this time, but oceanic-continental subduction continued to the Middle-Late Miocene.

Fig. 1
Fig. 1 Structural map of the Iran Plateau and the Zagros Orogen.Only Neotethys-related ophiolites are shown; dashed lines are concealed faults and solid lines are main faults

Fig. 2
Fig. 2Schematic cross-section from structural elements of the ZOB (not to scale).These structural elements from NE to SW include cover sediments, the Cenozoic Magmatic Belt, the Inner Ophiolite Belt (Khoy-Nain-Shahr Babak-Dehshir-Baft Ophiolites), the Second Metamorphic Belt, the Mesozoic Magmatic Belt (island arc), the First Metamorphic Belt, the Outer Ophiolite Belt (Neyriz-Kermanshah-Haji-Abad Ophiolites), the Crush Zone (or High Zagros), the Fold and Thrust Belt, the Dezful Embayment, and the Persian Gulf-Mesopotamian Foreland

Fig. 6
Fig. 6 Reconstruction history of the ZOB.(a) Formation of the Neotethys Basin triple junction.(b) Spreading and maturation in the Late Triassic.(c) Beginning of subduction of the southern Neotethys Basin and formation of the Khoy Back-arc Basin and Nain-Baft Back-arc Basin in the Early Jurassic, and then the beginning of subduction of the Neotethys back-arc basin in the Late Jurassic.(d) Closure of the Neotethys Back-arc Basin and the Neotethys southwestern subduction in the Late Cretaceous-Paleocene. (e) Recent structural elements of the ZOB

Fig. 7
Fig. 7 Reconstruction history of the SE ZOB

Fig. 9
Fig. 9 Reconstruction history of the NW ZOB