The tallest mountains, those over 14, ft 4, m , are located in the center of the range, including the tallest peak in the range, Zardeh Kuh 14, ft or 4, m.
The Zagros range, in general, is characterized by sheer rugged peaks and steep canyons and gorges. The mountains encompass several lakes as well, including Iran's largest inland body of water, Lake Urmia. Because of their elevation , the Zagros Mountains have a more subtropical climate than the drier areas below. Search the events calendar for forthcoming conferences and events, and view past meeting resources.
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The Geological Society of London is the UK's national society for geoscience, providing support to over 12, members in the UK and overseas. Founded in , we are the oldest geological society in the world. The oldest unit - the Gachsaran formation - is clastic in the northern part of the basin, but is dominated by evaporates in southern part, being deposited in a supratidal Sabkha-type environment. Overlying the Gachsaran is the Mishan formation, which is characterized by the Guri limestone member at the base, overlain by marine green marls.
The thickness of the Guri member increases dramatically towards the southeast. The next youngest unit is the Aghajari Formation which consists of well sorted lenticular sandstone bodies in a red silty-mudstone. This formation is interpreted as representing the floodplain of dominantly meandering rivers. Finally, the Bakhtiari formation consists of mainly coarse-grained gravel sheets which are interpreted to represent braided river deposits. Each of these Neogene depositional environments has a modern day equivalent.
For example, the braided rivers presently active in the Zagros mountains are modern analogues of the Bakhtiari. In the downstream direction, these braided rivers become meandering systems, which are equivalents of the Aghajari.
Finally, the modern carbonate system on the southern margin of Persian Gulf represents the Guri member paleo-environment, behind which Sabkha-type deposits similar to the Gachsaran are presently being deposited. One important implication of this link between the Neogene foreland basin deposits and the. S 13 Nov. Gulf of Oman is at lower left edge and the Persian Gulf is large body of water in upper half of photo. Photo credit: NASA. North Africa and the Middle East possess rich geological heritage, but the latter is yet to be fully identified and described.
The Oligocene carbonate platform of the Zagros Basin in southwest Iran , which corresponds to the lower part of the Asmari Formation, has significant potential for geoconservation and geotourism. The types of the geological heritage, their value, and the possible geosites have been assessed.
The studied deposits are interesting because of lithology carbonate rocks , fossils larger foraminifera, other microfossils, diverse marine invertebrates, fish microremains, and trace fossils , biostratigraphical developments, facies homoclinal carbonate ramp and signature of global events glacioeustatic fluctuations , and outstanding hydrocarbon resources. The five main geological heritage types are sedimentary, palaeontological, stratigraphical, palaeogeographical, and economical, from which the palaeontological, palaeogeographical, and economical types are of global rank.
The Khollar and Kavar sections in the Fars Province of Iran are recommended as geosites suitable for research, education, and tourism. The high complexity of the geological heritage linked to the Oligocene carbonate platform of the Zagros Basin implies the phenomenon of geodiversity should be understood with regard to the relationships between types and their values.
Gulf of Oman is large body of water at left and the Persian Gulf is body of water at right. View is looking east. We use observations of surface faulting, well-constrained earthquake focal mechanisms and centroid depths, and velocity structure to investigate the present-day deformation and kinematics of the region.
These belts are separated by seismically inactive regions that act as semi-rigid blocks. The extent to which the active shortening is divided between the three belts is still uncertain.
Earthquake locations in the region, particularly their focal depths which are determined from teleseismic arrival times, are poor, and reported subcrustal earthquakes have been cited as evidence for present-day subduction beneath the Zagros. A detailed analysis of earthquake focal depths in the Zagros and elsewhere in the region confirms that no substantial subcrustal earthquakes occur in this part of the Middle East except beneath the Makran subduction zone in the south and the Apsheron-Balkhan Sill in the north.
The south Caspian basin is essentially free of earthquakes and acts as a rigid block which strongly influences the nature of the deformation in the surrounding active belts. No significant subcrustal earthquakes occur in the Talesh, Alborz, or Kopeh Dag Mountains which bound the northeast, south and west sides of the south Caspian basin, but substantial subcrustal seismicity occurs beneath the Apsheron.
Earthquake hazard assessment in the Zagros Orogenic Belt of Iran using a fuzzy rule-based model. Producing accurate seismic hazard map and predicting hazardous areas is necessary for risk mitigation strategies. In this paper, a fuzzy logic inference system is utilized to estimate the earthquake potential and seismic zoning of Zagros Orogenic Belt. In addition to the interpretability, fuzzy predictors can capture both nonlinearity and chaotic behavior of data, where the number of data is limited.
In this paper, earthquake pattern in the Zagros has been assessed for the intervals of 10 and 50 years using fuzzy rule-based model. The Molchan statistical procedure has been used to show that our forecasting model is reliable. The earthquake hazard maps for this area reveal some remarkable features that cannot be observed on the conventional maps.
Regarding our achievements, some areas in the southern Bandar Abbas , southwestern Bandar Kangan and western Kermanshah parts of Iran display high earthquake severity even though they are geographically far apart.
PubMed Central. Biogeographic barriers for freshwater biota can be effective at various spatial scales. At the largest spatial scale, freshwater organisms can become genetically isolated by their high mountain ranges, vast deserts, and inability to cross oceans.
Isolation by distance of aquatic plants is expected to be stronger across than alongside mountain ridges whereas the heterogeneity of habitats among populations and temporary droughts may influence connectivity and hamper dispersal.
Suitable aquatic plant habitats became reduced, even for the widespread submerged Potamogeton pectinatus L. We compared the level of genetic diversity in a heterogeneous series of aquatic habitats across Iran and tested their differentiation over distances and across mountain ranges Alborz and Zagros and desert zones Kavir , with values obtained from temperate region populations.
The diversity of aquatic ecosystems across and along large geographic barriers provided a unique ecological situation within Iran. Nine microsatellite loci revealed a very high number of alleles over all sites. At the level of populations, a positive correlation between allelic differentiation Dest with geographic distance was found. Overall, higher levels of diversity and a stronger differentiation was revealed among.
The lower part of the Lower to Upper Jurassic Surmeh Formation consists of a succession of shallow marine carbonates Toarcian-Aalenian overlain by a deep marine basinal succession Aalenian-Bajocian that grades upward to Middle to Upper Jurassic platform carbonates. The termination of shallow marine carbonate deposition of the lower part of the Surmeh Formation and the establishment of deep marine sedimentation indicate a change in the style of sedimentation in the Neotethys passive margin of southwest Iran during the Middle Jurassic.
To evaluate the reasons for this change and to assess the basin configuration during the Middle Jurassic, this study focuses on facies analysis and sequence stratigraphy of the basinal deposits pelagic and calciturbidite facies of the Surmeh Formation, referred here as 'lower shaley unit' in the Central Zagros region. The upper Aalenian-Bajocian 'lower shaley unit' overlies, with an abrupt contact, the Toarcian-lower Aalenian platform carbonates.
It consists of pelagic calcareous shale and limestone and calciturbidite facies grading to upper Bajocian-Bathonian platform carbonates. Calciturbidite deposits in the 'lower shaley unit' consist of various graded grainstone to lime mudstone facies containing mixed deep marine fauna and platform-derived material.
The calciturbidite layers are erosive-based and commonly exhibit graded bedding, incomplete Bouma turbidite sequence, flute casts, and load casts. The 'lower shaley unit' constitutes the late transgressive and the main part of the highstand.
Sinkholes, collapse structures and large landslides in an active salt dome submerged by a reservoir: The unique case of the Ambal ridge in the Karun River, Zagros Mountains , Iran. Ambal ridge, covering 4 km2, is a salt pillow of Gachsaran Formation with significant salt exposures in direct contact with the Karun River, Zagros Mountains.
The highly cavernous salt dome is currently being flooded by the Gotvand Reservoir, second largest in Iran. Geomorphic evidence, including the sharp deflection of the Karun River and defeated streams indicate that Ambal is an active halokinetic structure, probably driven by erosional unloading. Slope oversteepening related to fluvial erosion and halokinetic rise seems to be the main controlling factor. The depressions occur preferentially along a belt with a high degree of clustering.
This spatial distribution is controlled by the proximity to the river, slope gradient and halite content in the bedrock. A large compound depression whose bottom lies below the normal maximum level of the reservoir will likely be flooded by water table rise forming a lake. The impoundment of the reservoir has induced peculiar collapse structures m across, expressed by systems of arcuate fissures and scarps.
Rapid subsurface salt dissolution is expected to generate and reactivate a large number of sinkholes and may reactivate landslides with a significant vertical component due to lack of basal support. The Zagros hinterland fold-and-thrust belt in-sequence thrusting, Iran.
The collision of the Iranian microcontinent with the Afro-Arabian continent resulted in the deformation of the Zagros orogenic belt. The foreland of this belt in the Persian Gulf and Arabian platform has been investigated for its petroleum and gas resource potentials, but the Zagros hinterland is poorly investigated and our knowledge about its deformation is much less than other parts of this orogen.
Therefore, this work presents a new geological map, stratigraphic column and two detailed geological cross sections. This study indicates the presence of a hinterland fold-and-thrust belt on northeastern side of the Zagros orogenic core that consists of in-sequence thrusting and basement involvement in this important part of the Zagros hinterland. The in-sequence thrusting resulted in first- and second-order duplex systems, Mode I fault-bend folding, fault-propagation folding and asymmetric detachment folding which indicate close relationships between folding and thrusting.
A major lateral ramp in the basement beneath the Talaee plain with about one kilometer of vertical offset formed parallel to the SW movement direction and perpendicular to the major folding and thrusting. Crustal and lithospheric structure of the Alborz Mountains Iran and surrounding areas from integrated geophysical modeling.
The tectonic evolution of Alborz Mountains northern Iran and the South Caspian Basin as well as its transition into the Scythian and Turan platforms are yet an unsolved and debated problem. We found thin lithosphere km underneath Central Iran , whereas thick lithosphere up to km , is found underneath Arabia, the South Caspian Basin and the Turan Platform.
Crustal thickening is found under the Zagros and Alborz Mountains up to 58 km and under the Kopet-Dagh Mountains 48 km , whereas the thin crust under the southern Caspian Sea is interpreted as oceanic crust.
Modeling result of Profile I is shown below with the crust in gray scale darker gray: higher density and the lithospheric mantle with color-coded temperatures. Since some previous studies argued for the absence of a root under the Alborz, we tested different models to see whether it is possible to explain the data without a root beneath the Alborz and finally we found that it is impossible to fit the calculated data to the measured ones with a geologically reasonable model.
Below the South Caspian Sea, the form of the crust-mantle interface and the base of the lithosphere indicate a subduction of the South Caspian block towards the N-NW. Based on the temperature distribution, we calculated the vertically integrated rock rigidity along the profiles. It shows that a rheologically very strong South Caspian block is surrounded by weaker continental lithosphere which may explain the rigid-block subduction of the South Caspian block on the one hand and internal deformation of the lithosphere under the Kopet-Dagh on the other hand.
A combined magnetometry and gravity study across Zagros orogeny in Iran. In this work, the structural geology and the tectonic conditions of the Zagros orogeny along the route of Qom to Kermanshah cities were investigated using the combined geophysical methods of the airborne magnetometry and the ground-based gravity data. Airborne magnetometry data of Iran with a line space of survey, 7. At first, the airborne magnetic data were stably m downward continued to the ground surface in order to enhance minor changes of the Earth's magnetic field over the studied region.
Afterward, 3D inverse modeling of the magnetic data was implemented to the downward continued data, and subsequently the section of magnetic susceptibility variation along the desired route was extracted and imaged at depth. The acquired model could appropriately predict the observed magnetic data, showing low misfit values between the observation and the predicted data.
The analytic signal filter was applied to the reduced-to-pole RTP magnetic data leading to the determination of the active and probable hidden faults in the structural zones of the Zagros , such as Sanandaj-Sirjan, Central Domain CD and Urumieh-Dokhtar based upon the generated peaks along the profile of analytic signal filter.
In addition, the density variations of the subsurface geological layers were determined by 3D inverting of the ground-based gravity data over the whole study area, and extracting this property along the route. The joint models of magnetic susceptibility and density variation could appropriately localize the traces of faults along with the geologically and tectonically structural boundaries in the region. The locations of faults correspond well to the variation of geophysical parameters on the inverted sections.
Probable direction, slope and extension at depth of these faults were also determined on the sections, indicating a high tectonized zone of the Sanandaj-Sirjan Zone SSZ parallel to the zone of.
The Zagros orogenic belt and foreland basin formed during the Cenozoic Arabia-Eurasia collision, but the precise histories of shortening and sediment accumulation remain ambiguous, especially at the NW extent of the fold-thrust belt in Iraqi Kurdistan. This region is characterized by well-preserved successions of Cenozoic clastic foreland-basin fill and deformed Paleozoic-Mesozoic hinterland bedrock. The study area provides an excellent opportunity to investigate the linkage between orogenic wedge behavior and surface processes of erosion and deposition.
The aim of this research is to test whether the Zagros orogenic wedge advanced steadily under critical to supercritical wedge conditions involving in-sequence thrusting with minimal erosion or propagated intermittently under subcritical condition involving out-of-sequence deformation with intense erosion.
These results suggest that the MFF, represented by the thrust-cored Qaradagh anticline, represents a major episode of out-of-sequence deformation. Detrital zircon U-Pb analyses from the Neogene foreland-basin deposits show continuous sediment derivation from sources to the NNE in Iraq and western Iran , suggesting that out-of-sequence thrusting did not significantly alter sedimentary provenance.
Rather, intense hinterland erosion and recycling of older foreland-basin fill dominated sediment delivery to the basin. The irregular distribution of. Vergne, and M. Mokhtari Seismological evidence for crustal-scale thrusting in the Zagros mountain belt Iran , Geophys. J Int. Mokhtari , M. Farahbod, C. Tectono-sedimentary evolution of the Permian-Triassic extension event in the Zagros basin Iran : results from analogue modelling. Since the s, the largest oil and gas reservoirs have been discovered in the Permian-Early Triassic formationsin Saudi Arabia.
Thus, this time period is important for the discovery of new oil reserves in Iran. The Arabian passivecontinental margin has undergone lithospheric extension during the Permian-Triassic, which led to the formation of theNeo-Tethys.
The aim of this paper is to describe the development of the continental rift basin in the Zagros region basedon the tectono-sedimentological evolution. We have studied well-log data to specify the distribution of synrift depositsin the Zagros and have related this information to the modelling.
Environmental changes indicated by various sedimentarysequences, from a siliciclastic basin to a carbonate platform setting, are described. The Cambrian Hormuz salt, whichoverlies the metamorphosed Precambrian basement, becomes effective as a basal detachment layer influencing the styleof overburden deformation during the Permian-Triassic extension event.
We have investigated the formation of variousstructures linked to the presence or absence of the Hormuz layer by analogue modelling and relating these structures to theLate Palaeozoic sedimentation.
Based on results of the analogue modelling, we argue that the basal detachment layer Hormuzseries has contributed to the various structural styles of the extensional basin development in the Fars domain and theLorestan domain. Flexural bending of the Zagros foreland basin. We constrain and model the geometry of the Zagros foreland to assess the equivalent elastic thickness of the northern edge of the Arabian plate and the loads that have originated due to the Arabia-Eurasia collision.
The Oligo-Miocene Asmari formation, and its equivalents in Iraq and Syria, is used to estimate the post-collisional subsidence as they separate passive margin sediments from the younger foreland deposits. The depth to these formations is obtained by synthesizing a large database of well logs, seismic profiles and structural sections from the Mesopotamian basin and the Persian Gulf. The foreland depth varies along strike of the Zagros wedge between 1 and 6 km.
The foreland is deepest beneath the Dezful embayment, in southwest Iran , and becomes shallower towards both ends. We investigate how the geometry of the foreland relates to the range topography loading based on simple flexural models. Deflection of the Arabian plate is modelled using point load distribution and convolution technique.
The results show that the foreland depth is well predicted with a flexural model which assumes loading by the basin sedimentary fill, and thickened crust of the Zagros. The model also predicts a Moho depth consistent with Free-Air anomalies over the foreland and Zagros wedge.
The equivalent elastic thickness of the flexed Arabian lithosphere is estimated to be ca. We conclude that other sources of loading of the lithosphere, either related to the density variations e. We calculate the shortening across the Zagros assuming conservation of crustal mass during deformation, trapping of all the sediments eroded from the range in the foreland, and an initial crustal thickness of 38 km.
Tertiary stress field evolution in Sistan Eastern Iran. The Sistan orogenic belt in eastern Iran , near the boundary with Afghanistan, results from the closure of a branch of the Neo-Thethys: the Sistan Ocean. It was divided by Tirrul et al. Sistan is bordered by the Makran and Zagros formed by the closure of the Neo-Tethys to the south and by the Kopet Dagh formed by the closure of Paleo-Tethys to the North.
The aim of this study is to fill the gap between preliminary studies about the overall structure of the Sistan Suture Zone and recent investigations of active tectonics in the region e.
Questions herein addressed are: 1 how are stresses transfered throughout Iran from the Zagros to the Sistan belts? In order to answer these questions, we have determined paleostress evolution in the Sistan, using a direct inversion method for 42 microtectonic sites in almost all lithologies of the Neh complex and the Sefidabeh basin. These same three stages of deformation were also documented by several microtectonic studies in Iran , especially in Makran and Zagros.
The direction of the youngest compression is very homogeneous indicating that the mountain belts and continental blocks of Iran. The Zagros mountains extends over km from Kurdistan in N-Iraq to the Strait of Hormuz in Iran and is one of the world most promising regions for the future hydrocarbon exploration. The Zagros Mountains started to form as a result of the collision between the Eurasian and Arabian Plates, whose convergence began in the Late Cretaceous as part of the Alpine-Himalayan orogenic system.
Geodetic and seismological data document that both plates are still converging and that the fold and thrust belt of the Zagros is actively growing. Extensive hydrocarbon exploration mainly focuses on the antiforms of this fold and thrust belt and therefore the growth history of the folds is of great importance. This work investigates by means of structural field work and quantitative geomorphological techniques the progressive fold growth of the Permam, Bana Bawi- and Safeen- Anticlines located in the NE of the city of Erbil in the Kurdistan region of Northern Iraq.
This part of the Zagros fold and thrust belt belongs to the so-called Simply Folded Belt, which is dominated by gentle to open folding. Faults or fault related folds have only minor importance. The mechanical anisotropy of the formations consisting of a succession of relatively competent massive dolomite and limestone and incompetent claystone and siltstone sediments essentially controls the deformation pattern with open to gentle parallel folding of the competent layers and flexural flow folding of the incompetent layers.
The characteristic wavelength of the fold trains is around 10 km. Due to faster erosion of the softer rock layers in the folded sequence, the more competent lithologies form sharp ridges with steeply sloping sides along the eroded flanks of the anticlines.
Using an ASTER digital elevation model in combination with geological field data we quantified drainage basins along the different limbs of the subcylindrical Permam, Bana Bawi- and Safeen- Anticlines. Geomorphological indices of the drainage.
Neogene shortening and exhumation of the Zagros fold-thrust belt and foreland basin in the Kurdistan region of northern Iraq. Koshnaw, Renas I. The Zagros fold-thrust belt in the Kurdistan region of Iraq encroached southward toward a rapidly subsiding Neogene foreland basin and was later partitioned by out-of-sequence shortening focused along the Mountain Front Flexure MFF , as defined by new low-temperature thermochronologic, stratigraphic, and provenance results.
Distinct shifts in detrital zircon U-Pb provenance signatures for Neogene foreland basin fill provide evidence for drainage reorganization during fold-thrust belt advance. Such a sharp cutoff in Eurasian, Pan-African, and ophiolitic sources is likely associated with drainage reorganization and tectonic development of the geomorphic barrier formed by the MFF.
As a result of Zagros crustal shortening, thickening and loading, the Neogene foreland basin developed and accommodated an abrupt influx of fluvial clastic sediment that contains growth stratal evidence of synkinematic accumulation. The apparent out-of-sequence pattern of upper crustal shortening in the hinterland to foreland zone of Iraqi Kurdistan suggests that structural inheritance and the effects of synorogenic erosion and accumulation are important factors influencing the irregular and episodic nature of orogenic growth in the Zagros.
Middle to late Cenozoic basin evolution in the western Alborz Mountains : Implications for the onset of collisional deformation in northern Iran. Oligocene-Miocene strata preserved in synclinal outcrop belts of the western Alborz Mountains record the onset of Arabia-Eurasia collision-related deformation in northern Iran. Two stratigraphic intervals, informally named the Gand Ab and Narijan units, represent a former basin system that existed in the Alborz.
The Gand Ab unit is correlated with the Oligocene-lower Miocene Qom Formation of central Iran and is considered a product of thermal subsidence following Eocene extension. The Narijan unit unconformably overlies the Gand Ab unit and is composed of fluvial-lacustrine and alluvial fan sediments exhibiting contractional growth strata. We correlate the Narijan unit with the middle to upper Miocene Upper Red Formation of central Iran on the basis of lithofacies similarities, stratigraphic position, and an 8.
Deformation timing is constrained by crosscutting relationships and independent thermochronological data. The Parachan thrust system along the eastern edge of the ancestral Taleghan-Alamut basin is cut by dikes dated at 8.
Subhorizontal gravels that unconformably overlie tightly folded and faulted Narijan strata are capped by 2. The Zagros Mountain, a major mountain range in Central Asia , extends for a distance of 1, kilometers in a northwest to southeast direction from the border areas between eastern Turkey and northern Iraq across the Iranian Plateau, ending at the Strait of Hormuz in southern Iran. Mount Dena, with a peak achieving an elevation of 14, feet, is the highest peak in the Zagros Mountain system.
Limestone and shale rocks from the Mesozoic Era and Paleogene Period form the most commonly seen geological structural materials of the Zagros Mountains.
The oldest rocks found here date back to the Precambrian Period. A semi-arid temperate climate prevails in the region, wherein the bitter winters are severely cold and experience deadly temperatures drop, while summers are highly arid. Average annual precipitation ranges between millimeters and millimeters, and mostly falls during the late winter and early spring seasons.
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