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The Arabia – Eurasia collision zone in the central part of the Alpine – Himalayan orogenic system has had a complex deformation history since the Palaeozoic. In Iran, the collision zone consists of the Alborz‐Talesh, Kopeh Dagh and Zagros foldbelts and the intervening Central Iran area. In this review paper, we summarize the structural architecture and tectonostratigraphic characteristics of these domains and attempt to correlate regional deformation events between them. The results show that six regional‐scale deformation phases can be recognized and correlated in Iran over a time interval extending from the Late Palaeozoic to the Late Cenozoic. Late Palaeozoic rifting in northern Gondwana and subsequent oceanic spreading resulted in the separation of the Central and North Iran blocks from the Arabian Platform. These blocks later converged and collided with the southern margin of Eurasia due to the subduction of the intervening PalaeoTethys lithosphere ("Cimmerian orogeny": Late Triassic). The convergent setting resulted in the initial development of the Alborz‐Talesh foldbelt in present‐day northern Iran, while extensional basins developed in the forebulge area in Central Iran. Continuing northward subduction of NeoTethyan oceanic lithosphere at the southern Eurasia margin produced Early Cretaceous back‐arc extension and associated volcanism in Central Iran and the Alborz‐Talesh area to the north. A phase of compressional deformation in the Late Cretaceous was related to the collision of a series of microcontinents derived from Northern Gondwana, including the Ercinjan and Bitlis massifs, with the Central Iran block, and is recorded in the Alborz‐Talesh foldbelt and in Central Iran. Further back‐arc extension in the late Paleocene – Eocene was accompanied by pervasive volcanism and volcaniclastic sedimentation throughout northern and Central Iran. The final closure of NeoTethys and convergence between the Arabian and Eurasian Plates evolved through phases of early Oligocene "soft" collision and middle Miocene "hard" collision. This was accompanied by thrusting in the internal parts of the Zagros foldbelt and by folding and subordinate thrusting in the more external parts, with related development of the flexural Mesopotamian Basin in the foreland to the SW. [ABSTRACT FROM AUTHOR]

A doublet earthquake event including two main shocks with a magnitude larger than Mw 6.0 occurred on 1 July 2022 in the Zagros fold‐and‐thrust belt, southeast Iran. The coseismic InSAR deformation field shows that this event caused significant surface uplift due to fault‐related folding in the seismic zone. The estimated preferred faulting model suggests that a higher dip angle fault (maximum slip of ∼1.1 m), and an overlying gentle dipping fault (maximum slip of ∼1.2 m) within the Bandar‐e‐Lengeh Anticline, are responsible for the first and second main shocks, respectively. The calculated Coulomb failure stress change suggests that the first main shock and its Mw 5.7 aftershock have a significantly positive triggering effect in the second main shock. The accumulated interseismic strain should have been partly released by the two main shocks. Finally, the salt diapir activity may affect the generation of the earthquake in the seismic zone. Plain Language Summary: The doublet earthquake frequently occurred in the southeast part of the Zagros fold‐and‐thrust belt in the past years. In this study, we first adopted the Synthetic Aperture Radar images captured by Sentinel‐1 satellite to map the coseismic surface deformation of the 2022 Hormozgan doublet earthquake. The uplift of fault‐related folding controls the coseismic surface motion of these events from blind thrusting. Moreover, the two main shocks are caused by the rupture of two faults within the Bandar‐e‐Lengeh Anticline. Furthermore, the first main shock increased the stress in the source area of the second main shock, and positive triggered the rupture of the seismogenic fault of the second main shock. The interseismic surface deformation suggests that the 2022 Hormozgan doublet earthquake may have released the accumulated interseismic strain for the past ∼104 years. In addition, salt diapir activity in the southeast part of the seismic zone may contribute to the 2022 Hormozgan doublet earthquake. Key Points: A doublet earthquake occurred in the southeastern of Zagros fold‐and‐thrust belt with a significant salt layers activityA combination of steep and shallow blind faults is responsible for the 2022 Hormozgan doublet earthquakeThe interseismic strain accumulation and salt diapir activity in the southeast of the seismic zone may cause this doublet earthquake [ABSTRACT FROM AUTHOR]

Structural decoupling in the Zagros fold‐and‐thrust belt, SW Iran, is controlled by the presence of intermediate detachment horizons within the Phanerozoic stratigraphic column such as intervals rich in evaporites. The effectiveness of the detachment horizons varies across the Zagros, and controls the style of folding and therefore the formation of structural traps. In this paper, field mapping, seismic interpretation and well data is used to investigate the complex structural style at six large‐scale anticlines located on either side of the surface trace of the NW‐SE trending Zagros Frontal Fault system in the South Dezful Embayment (Central Zagros). At some of these anticlines, lower – middle Miocene evaporites in the Gachsaran Formation decouple the folded overlying succession from the competent, underlying interval which includes the Asmari Formation reservoir. Anticlines to the northeast of the surface exposure of the fault have undergone four times more shortening than anticlines to the southwest. This localized shortening compared to regional values has resulted in some cases in complex asymmetric folding, and in severe structural decoupling above and below the Gachsaran Formation. However, other anticlines to the NE of the fault which underwent a similar amount of shortening, but in which the thickness of the Gachsaran Formation is reduced and the salt content is lower, show a harmonic style of folding above and below the formation. Thus, the efficiency of the Gachsaran detachment varies throughout the study area and appears to be controlled mainly by the total thickness of the formation, the net thickness of salt‐rich intervals within it, and the amount of structural shortening across the Zagros Frontal Fault system. These observations could be relevant to similar structural domains both in the Zagros and in other fold‐and‐thrust belts where intermediate detachment horizons and regional‐scale faults have together controlled the configuration of folds and structural traps. [ABSTRACT FROM AUTHOR]

Salt tectonics in the Eastern Persian Gulf (Iran) is linked to a unique salt‐bearing system involving two overlapping 'autochthonous' mobile source layers, the Ediacaran–Early Cambrian Hormuz Salt and the Late Oligocene–Early Miocene Fars Salt. Interpretations of reflection seismic profiles and sequential cross‐section restorations are presented to decipher the evolution of salt structures from the two source layers and their kinematic interaction on the style of salt flow. Seismic interpretations illustrate that the Hormuz and Fars salts started flowing in the Early Palaeozoic (likely Cambrian) and Early Miocene, respectively, shortly after their deposition. Differential sedimentary loading (downbuilding) and subsalt basement faults initiated and localized the flow of the Hormuz Salt and the related salt structures. The resultant diapirs grew by passive diapirism until Late Cretaceous, whereas the pillows became inactive during the Mesozoic after a progressive decline of growth in the Late Palaeozoic. The diapirs and pillows were then subjected to a Palaeocene–Eocene contractional deformation event, which squeezed the diapirs. The consequence was significant salt extrusion, leading to the development of allochthonous salt sheets and wings. Subsequent rise of the Hormuz Salt occurred in wider salt stocks and secondary salt walls by coeval passive diapirism and tectonic shortening since Late Oligocene. Evacuation and diapirism of the Fars Salt was driven mainly by differential sedimentary loading in annular and elongate minibasins overlying the salt and locally by downslope gliding around pre‐existing stocks of the Hormuz Salt. At earlier stages, the Fars Salt flowed not only towards the pre‐existing Hormuz stocks but also away from them to initiate ring‐like salt walls and anticlines around some of the stocks. Subsequently, once primary welds developed around these stocks, the Fars Salt flowed outwards to source the peripheral salt walls. Our results reveal that evolving pre‐existing salt structures from an older source layer have triggered the flow of a younger salt layer and controlled the resulting salt structures. This interaction complicates the flow direction of the younger salt layer, the geometry and spatial distribution of its structures, as well as minibasin depocentre migration through time. Even though dealing with a unique case of two 'autochthonous' mobile salt layers, this work may also provide constraints on our understanding of the kinematics of salt flow and diapirism in other salt basins having significant 'allochthonous' salt that is coevally affected by deformation of the deeper autochthonous salt layer and related structures. PMB‐HS and PMB‐FS: Primary minibasins and/or rim synclines above the autochthonous Hormuz Salt and Fars Salt, respectivelyPW‐HS and TW‐HS: Primary and tertiary salt welds at the autochthonous and allochthonous levels of the Hormuz Salt, respectivelyPW‐FS: Primary salt weld at the level of the autochthonous Fars Salt Salt tectonics in the Eastern Persian Gulf arises from Hormuz Salt and Fars Salt autochthonous source layers. The main driving forces of the Hormuz Salt movement were downbuilding and contractional squeezing. The diapirs of Hormuz Salt extruded significant allochthonous salt at Palaeocene–Eocene times. Pre‐existing diapirs of Hormuz Salt have influenced the flow of Fars Salt. Evacuation and diapirism of Fars Salt was driven mainly by differential sedimentary loading. [ABSTRACT FROM AUTHOR]

Abstract: We reveal transient surface deformation following the 2017 Mw7.3 Sarpol Zahab (Iran) earthquake using Interferometric Synthetic Aperture Radar (InSAR) measurements. Based on the coseismic interferograms derived from the Advanced Land Observing Satellite‐2 (ALOS‐2) data, the preferred slip model of the earthquake has a centroid depth of 14.5 ± 4 km and suggests that a basement fault is most likely responsible for the 2017 earthquake in the northwest Zagros fold‐thrust belt zone. Two slip asperities with a maximum slip of 6 m separated by 16 km are observed in the best fitting slip model. The accumulated afterslip in the first month after the mainshock determined from the Sentinel‐1 postseismic interferograms reveals a slip distribution that lies immediately updip of the coseismic slip, implying that frictional properties of the fault vary along the rupture patch. The Bamo Mount in the earthquake area was uplifted by approximately 1 m during the earthquake. We suggest that local topographic growth from both seismic and aseismic faulting behaviors is common within the Zagros fold‐thrust belt zone based on our findings regarding the 2017 earthquake and other significant events in the region. [ABSTRACT FROM AUTHOR]

The Talesh Mountains at the NW margin of the Iranian Plateau curve around the southwestern corner of the South Caspian Block and developed in response to the collision of the Arabian-Eurasian Plates. The timing, rates, and regional changes in late Cenozoic deformation of the Talesh Mountains are not fully understood. In this study, we integrate 23 new apatite and zircon bedrock U-Th/He ages and structurally restored geologic cross sections with previously published detrital apatite fission track data to reconstruct the deformation history of the Talesh Mountains. Our results reveal that slow rock exhumation initiated during the late Oligocene (~27-23 Ma) and then accelerated in the middle Miocene (~12 Ma). These events resulted in the present-day high-elevation and curved geometry of the mountains. The spatial and temporal distribution of cooling ages suggest that the Oligocene bending of the Talesh Mountains was earlier than in the eastern Alborz, Kopeh Dagh, and central Alborz Mountains that initiated during the late Cenozoic. Late Oligocene and middle Miocene deformation episodes recorded in the Talesh Mountains can be related to the collisional phases of the Arabian and Eurasian Plates. The lower rate of exhumation recorded in the Talesh Mountains occurred during the initial soft collision of the Arabian-Eurasian Plates in the late Oligocene. The accelerated exhumation that occurred during final collision since the middle Miocene resulted from collision of the harder continental margin. [ABSTRACT FROM AUTHOR]

The left-lateral Doruneh Fault System (DFS) bounds the north margin of the Central Iranian microplate and has played an important role in the structural evolution of the Turkish-Iranian plateau. The western termination of the DFS is a sinistral synthetic branch fault array that shows clear kinematic evidence of having undergone recent slip sense inversion from a dextral array to a sinistral array in the latest Neogene or earliest Quaternary. Similarly, kinematic evidence from the Anarak Metamorphic complex suggests that this complex initially developed at a transpressive left-stepping termination of the DFS and that it was inverted in the latest Neogene to a transtensional fault termination. The recognition that the DFS and other faults in NE Iran were inverted from dextral to sinistral strike slip in the latest Neogene and the likely connection between the DFS and the Herat Fault of Afghanistan suggests that prior to the latest Miocene, all of the north Iranian and northern Afghan ranges were part of a distributed dextral fault network that extended from the west Himalayan syntaxes to the western Alborz. Also, the recognition that regional slip sense inversion occurred across northern and northeastern Iran after the latest Miocene invalidates tectonic models that extrapolate Pleistocene to recent fault slip kinematics and rates back beyond this time. [ABSTRACT FROM AUTHOR]

A metamorphic core complex model is proposed for Khoshoumi Mountain uranium mineralization located in the Bafq-Saghand metallogenic zone of central Iran. Uranium mineralization occurred in the Chapedoni metamorphic complex. Detailed structural analysis of the complex leads to the interpretation that the mineralization is spatially concentrated in a low angle shear zone of mylonitized migmatite, the lower ductile part of the Chapedoni metamorphic complex. The shear zone that has top to the NE sense of shear in the northeastern and southeastern parts of the mountain and top to the WNW sense of shear in the southwestern part is a detachment zone to the Chapedoni Metamorphic Core Complex (CMCC). The Eocene granite is the plutonic core to the CMCC. The shear zone is cut by several NE-trending left-lateral strike-slip faults. This later faulting is interpreted to account for the significant enrichment of uranium in the southern part of the mountain. The bimodal distribution of radiometric data gathered from exploratory drill holes in this part of the mountain constrains this interpretation. That is, the lower value is from the shear zone across the area but the higher value is from the places that the shear zone is cut by the transverse faults. [ABSTRACT FROM AUTHOR]