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(a) Digital elevation map showing basic geological data in the Zagros fold‐and‐thrust belt, specifically: the Main Zagros Thrust (MZT), the High Zagros Fault (HZF), and the Mountain Front Fault (MFF). Locations of sections mentioned in the text are also marked. (b) Geological map showing the thrusts, anticlines, and the position of Figure 2 in the Dezful Embayment (modified from Etemad‐Saeed et al., 2020). Locations with ages of growth strata are also shown.
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The timing of tectonic deformation in the Zagros foreland basin provides important information about the tectonic propagation process driven by the Arabia‐Eurasia convergence. The chronology of growth strata is one of the most important methods to delimit the history of folding and thrusting within the foreland basin. In this study, we report integ...
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The Cenozoic strata of the Xining Basin, NE Tibet, have provided crucial records for understanding the tectonic and paleo‐environmental evolution of the region. Yet, the age for the lower part of the sedimentary stratigraphy and consequently the early tectonic evolution of the basin remain debated. Here, we present the litho‐ and magnetostratigraph...
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... During the late Oligocene to early Miocene, the Neotethys Sea stretched from Europe to West Asia, linking the Atlantic Ocean in the west and the Indian Ocean in the southeast (Rögl, 1999;Popov et al., 2004;Mohammadi, 2021). During this time, both the Qom back-arc basin and the Zagros foreland basin were part of the eastern Neotethys Sea, forming a large shallow epicontinental sea in Iran and connecting with the proto-Mediterranean Sea (Reuter et al., 2009;Sun et al., 2022). However, seawater retreated from Central Iran due to ongoing collision between Arabia and Asia, blocking the connection between Central Iran and the Tethyan Seaway Reuter et al., 2009;Sun et al., 2021a) at around the late Burdigalian based on biostratigraphic constraints (Reuter et al., 2009) and a later magnetostratigraphic age of ~17 Ma (Sun et al., 2021a). ...
... Compared with the seawater retreat from Central Iran, the timing of Tethyan Seaway closure in the west of the Zagros thrust belt was much later (e.g., Homke et al., 2004;Pirouz et al., 2015;Hüsing et al., 2009;Ruh et al., 2014;Bialik et al., 2019;Sun et al., 2021bSun et al., , 2022. From sedimentary evidence, the early to mid-Miocene Gachsaran Formation (lagoon and evaporitic sabkha) was distributed widely in the Tethyan Seaway with a 1500 km length of and 300 km maximum width (Jones and Racey, 1994;Ehrenberg et al., 2007;Sun et al., 2022). ...
... Compared with the seawater retreat from Central Iran, the timing of Tethyan Seaway closure in the west of the Zagros thrust belt was much later (e.g., Homke et al., 2004;Pirouz et al., 2015;Hüsing et al., 2009;Ruh et al., 2014;Bialik et al., 2019;Sun et al., 2021bSun et al., , 2022. From sedimentary evidence, the early to mid-Miocene Gachsaran Formation (lagoon and evaporitic sabkha) was distributed widely in the Tethyan Seaway with a 1500 km length of and 300 km maximum width (Jones and Racey, 1994;Ehrenberg et al., 2007;Sun et al., 2022). The restricted marine environment changed to intermittent marine connections between ~13.8 and 12.8 Ma, as evidenced by alternating terrestrial red beds and thin marine intercalations in the foreland basins in the footwalls of both the High Zagros (Lurestan Arc) and the Mountain Front Fault (Dezful Embayment) with a ~ 100-kyr cycle (Sun et al., 2021b(Sun et al., , 2022. ...
... 其中, 曾 经 连 通 印 度 洋 、 特 提 斯 海 、 北 冰 洋 的 图 尔 盖 海 峡 (图1(b))在48 Ma关闭 [11] , 导致北冰洋一度成为孤立的 海盆且海水变淡并爆发著名的满江红(Azolla)生物事 件, 也由此导致了北冰洋生产力的提高以及巨量有机 碳的埋藏, 这很可能是早始新世气候高温期结束的重 要原因. 曾经在始新世和渐新世连通印度洋、特提斯 海、北大西洋的特提斯海峡(图1(b), (c))也在中-中新 世晚期(13 Ma)永久关闭 [12,13] . 新生代大陆汇聚导致的 [14] . ...
... 相环境 [12] , 这一时间节点恰逢中-中新世气候适宜期 [49] ; (b), (c) the chronology and timing of seawater retreat in two key sections in the Zagros foreland basin (the Tethyan Seaway) [12,13] 撤退, 但特提斯海峡为海岸潟湖为主的沉积, 间歇性 存在浅海相环境, 此时特提斯海峡仅可能允许少量的 ...
... 特提斯海峡已经转变为陆相为主的环境, 仅存在短 暂、间歇性海侵, 且具有10万年的准周期(图5(c)); (4) 晚中新世(12.8 Ma)以来, 特提斯海峡永久关闭 [12,13] (图5(d)). [50] . ...
... In light of the widely distributed Paleocene to middle Miocene data in Fig. 9 (purple, light blue and yellow symbols), we fully agree that tectonic stresses related to the Arabian motion can transmit efficiently over large distances after mechanical coupling of the two plates. Stress propagation of the Arabia-Eurasia plate convergence and its accommodation by pre-existing faults in the hinterland caused the Miocene growth of the Zagros, Alborz and Caucasus (Albino et al., 2014;Cavazza et al., 2017;Sun et al., 2022). The Zagros orogenic belt and its hinterland are in some ways comparable with the Tibetan plateau and the Tianshan mountain range. ...
NW Iran, situated between the Arabian and Eurasian plates, carries a record of both Paleo-Tethyan and Neo-Tethyan tectonic evolution. During the Wilson Cycle of Tethys Ocean opening and closing, several episodes of magmatism from Late Paleozoic to latest Cenozoic generated a massive volume of intrusive rocks. These intrusives, which record cooling histories from high-temperatures to final exhumation, are ideal for multiple geo-thermochronological studies. Our new zircon and apatite Usingle bondPb results suggest three regional magmatic events in the Late Carboniferous, mid-Cretaceous and middle Eocene, which could be related to Paleo-Tethys subduction, Neo-Tethys subduction and Neo-Tethyan ridge subduction, respectively. New apatite fission track and (Usingle bondTh)/He data reveal post-magmatic cooling and differential exhumation related to subduction and collision. By integrating published regional thermochronological data from northeastern part of the Middle East, a broader tectono-thermal framework is outlined as follows: 1) Cretaceous cooling signals are most pronounced in the Alborz and Caucasus, and reflect back-arc extension during Neo-Tethyan subduction; 2) diachronous Neo-Tethyan evolution led to the Paleocene assemblage of Anatolia in the west, and subduction associated with a late Paleocene-Eocene magmatic flare-up in Iran. Subsequent westward escape of Anatolia and extensive surface uplift were driven by propagation of Arabia-Eurasia collision in the Miocene; 3) Continuous northward indentation of Arabia into Eurasia triggered late Miocene-Pliocene fast exhumation of the Zagros, Alborz and the Caucasus.
... In this region, several tectonic units are divisible from northeast to southwest with non-uniform deformation [10]. Tectonic slices of the highly deformed domain of thrust zone, including the Arabian margin, remains of island arcs, fragments of Cretaceous ophiolites and accretionary prisms, developed above a basal detachment in the latest Neoproterozoic-Lower Cambrian Hormuz evaporates or lateral equivalent [17,20,22]. In the Zagros belt, the deformation and tectonic process that reactivated the Late Cretaceous-Paleogene obduction belt is characterized by thin-and thick-skinned tectonics [17]. ...
... In the Zagros belt, the deformation and tectonic process that reactivated the Late Cretaceous-Paleogene obduction belt is characterized by thin-and thick-skinned tectonics [17]. Tectonic deformation of the Zagros foreland basin was closely related to the propagation of faults from the Arabia-Eurasia suture zone to the southwestern side [22]. The Simply Folded Belt, limited by the HZF and the MFF, is characterized by many elongated anticlines. ...
... The estimations of the causative fault agree with the previously known local structures, which cut simple sediment folding of Bakhtiari, Lahbari and Aghajari formations ( Figure 1) in low folded zone in Dezful Embayment [17,22]. This fault can control the local fault-related folding and the frontal fold growth of large surface anticlines [21]. ...
On 18 April 2021, a MW 5.8 earthquake occurred near the city of Bandar-e Genaveh, southwestern Iran. Four synthetic aperture radar (SAR) images, acquired from Sentinel-1 (ESA Copernicus project) satellites in ascending and descending orbits, were used to get two displacement maps, catching the surface co-seismic effects through the two-pass InSAR technique. Modeling the
deformation patterns using equations for a shear dislocation in elastic half-space allowed the source
parameters and the slip distribution of the seismogenic source to be determined. We calculated that the rupture occurred on a reverse fault extending NW-SE, gently dipping NE and with a maximum slip reaching about 1 m. The northeast and low-dip angle of this fault are also consistent with the tectonics of the region, which is subject to deformation and shortening along the northern margin of the Arabian plate. Our estimations of the fault parameters agree with the Zagros Foredeep reverse fault. We additionally processed four other SAR images to investigate the possibility that the Mw 5.0 aftershock, which occurred about one month later, induced surface effects visible with InSAR. This analysis, however, did not provide any clear conclusions.
The timing of deformation and the age of sediments in foreland basins are key information for reconstructing the
tectonic history of orogenic belts. This study, utilized magnetostratigraphic techniques to determine the ages of
~ 2.5 km-thick strata within the Zagros folded foreland basin in the flank of the NW-SE-trending Emam Hassan
anticline, located above the N–S-trending Khanaqin blind basement fault. This fault separates the Lurestan arc in
Iran from the Kirkuk embayment in Iraqi Kurdistan. These ages were combined with a detailed structural study to
establish the timing of folding and integrate it into the regional framework of the Zagros folded belt. Magne-
tostratigraphic results indicate a Serravallian age at ~ 13.4 Ma for the stratigraphic boundary between the
Gachsaran Formation and the pre-growth Aghajari Formation, whereas the base of the Aghajari growth strata is
Tortonian age (early Late Miocene) at ~ 10 Ma. The mean sediment accumulation rate for the Aghajari For-
mation is ~ 44 cm/kyr, with short peaks reaching up to 90 cm/kyr. Linear extrapolation of these rates proposes a
younger age than ~ 6.5 Ma (Messinian) for the base of the unconformable conglomerates of the Bakhtyari
Formation. The Emam Hassan folding and related Gachsaran diapirism began ~ 10 Ma and continued for at least
3.5 Myr until ~ 6.5 Ma, coevally with the deposition of ~ 1.3 km of the upper Aghajari Formation. Regional
synthesis reveals that multi-detachment folding within the Lurestan arc propagates in-sequence towards the
foreland. Although not the central focus of this study, our results, combined with the regional structural un-
derstanding, illustrate the potential 3-D structure at the depth of the seismogenic Khanaqin Fault, the source of
the 2017 Mw 7.3 Sarpol-e Zah¯ab Earthquake.
The Zagros foldbelt – foreland system in SW Iran is a prolific hydrocarbon province with known reserves of more than 90 billion brl of oil and 800 TCF of natural gas. Establishing the structural style of folding in the Zagros area presents a major challenge due both to the geographical extent of the foldbelt, which is some 1600 km long in total, and the presence of marked lateral variations in fold style related to the complex regional tectonic history. In addition, while numerous high‐quality structural studies of the Zagros have been completed over the last 20 years, they support a variety of different interpretations and are therefore $$difficult to synthesize. In this paper, we review the general structural style of the Zagros fold‐and‐thrust belt in SW Iran, and in particular the style of folding in the Lurestan arc, Dezful embayment, Izeh Zone and Fars arc. We summarise relationships between folding in these areas and fracture development, and investigate the timing of folding and the interaction between NW‐SE oriented “Zagros” folds and north‐south oriented “Arabian” folds. Finally, we briefly assess the implications of fold style for petroleum systems in the Zagros area. Although no new data are presented in this paper, a series of unpublished maps are used to illustrate the main results and include: a map showing the extent of the main detachment levels across the Lurestan, Dezful and Fars structural domains; two palaeotectonic maps (for Late Cretaceous – Paleocene and Miocene – Pliocene times, respectively), showing the position of the deformation fronts of the Zagros and the North Oman thrust systems and their potential spatial and temporal relationship with folding; and a set of four maps showing the distribution of reservoir rocks which are grouped by age into the Permian – Triassic Dehram Group, the Late Jurassic – Early Cretaceous Khami Group, the Late Cretaceous Bangestan Group, and the Oligocene – Miocene Asmari Formation. In addition, for the Lurestan, Dezful and Fars structural domains, a series of regional cross‐sections at the same scale are presented and discussed.
Most of the data in this review paper were acquired in order to gain an improved understanding of the petroleum systems in the Zagros area; however the data are used here to investigate a range of interacting processes including tectonics, sediment deposition and subsurface fluid flow in the development of the fold‐and‐thrust belt and its associated foreland basins. The resulting synthesis is intended to provice a starting point for future tectonostratigraphic and hydrocarbon‐related studies which will make use of both existing and new multidisciplinary techniques to constrain the results. The knowledge acquired and the techniques used will be of benefit in future challenges including the identification of subsurface reservoirs suitable for the permanent storage of CO 2 to mitigate the effects of climate change.
Considering the Neo-Tethyan tectonic process and the resulting environmental changes, a geodynamic model of “one-way train loading” is proposed to analyze the formation and evolution mechanism of the Persian Gulf Superbasin with the most abundant hydrocarbons in the world. The Persian Gulf Superbasin has long been in a passive continental margin setting since the Late Paleozoic in the process of unidirectional subduction, forming a superior regional space of hydrocarbon accumulation. During the Jurassic–Cretaceous, the Persian Gulf Superbasin drifted slowly at low latitudes, and developed multiple superimposed source-reservoir-caprock assemblages as a combined result of several global geological events such as the Hadley Cell, the Equatorial Upwelling Current, and the Jurassic True Polar Wander. The collision during the evolution of the foreland basin since the Cenozoic led to weak destruction, which was conducive to the preservation of oil and gas. Accordingly, it is believed that the slow drifting and long retention in favorable climate zone of the continent are the critical factors for hydrocarbon enrichment. Moreover, the prospects of hydrocarbon potential in other continents in the Neo-Tethyan were proposed.
As a typical dwarf antelope, the extant Nesotragus is confined to shrub areas of open woodlands and forests in Eastern and Central Africa. Molecular phylogenetic reconstructions reveal that Nesotragus, along with Aepyceros (impala), represents the earliest crown group of Antilopinae. However, to our knowledge, fossils in relation to Nesotragus have to date not been found. Here, we report the recent discovery of a fossil dwarf antelope, Linxiatragus dengi gen. et sp. nov., from the early Late Miocene (10–9 Ma) of the Linxia Basin, adjoining the NE Tibetan Plateau. This is the first report of a fossil dwarf antelope outside of Africa and prior to Pliocene. Phylogenetic reconstructions confirm that L. dengi belongs to the clade of extant Nesotragus. Morphometric studies further suggest that the cranial morphology of Linxiatragus is intermediate between the extant Nesotragus and Gazella. A microwear study indicates that unlike extant Nesotragus, L. dengi was possibly a grazer rather than a browser, revealing that extant Nesotragus are secondarily small, an adaptation to a concealing habitat. l. dengi, as well as some other taxa (e.g., Diceros gansuensis) occurring in the NE margin of the Tibetan Plateau in the early Late Miocene, suggests a relatively arid and open regional paleoenvironmental condition, which mimicked the African Savannah woodlands ecosystem. This ecological implication is consistent with the relatively open lands in the Linxia Basin prior to the tectonic uplift of the NE Tibetan Plateau, as indicated by geological evidence. These findings might provide a new interpretation for the origin and migration of modern Sub-Saharan African Savannah mammalian assemblage through the land-bridge connecting Arabia and Asia after their hard-collision.
