Eastern Alborz Mountains Research Articles

Geochemical constraints on the Gano karst bauxite deposit, eastern Alborz Mountains, northern Iran: Implications for provenance, elemental mobility, and distribution of critical metals

The Gano karst bauxite deposit is located in the eastern Alborz Mountains, 90 km NE of Semnan city, northern Iran. The layers and lenticular patches of bauxite are hosted in the Triassic karstified carbonate rocks interbedded with calcareous shale of the Elika Formation, unconformably overlain by siliciclastics of the early Jurassic Shemshak Formation. The bauxite ores have a mineral assemblage dominated by diaspore and hematite, with lesser kaolinite, illite, chlorite, goethite, anatase, dolomite, and quartz. In the Gano area, intrusions range from monzonite to quartz monzonite in composition with an alkaline composition that generated in an extensional regime within a plate tectonic setting. Geochemical signatures of the Gano bauxite ores suggest a derivation from the monzonite intrusions at the base of the Elika Formation, although a contribution of interbedded calcareous shale of the Elika Formation cannot be excluded. Based on the variation of Ce anomaly across the studied profile and the integration of petrographic evidence and mineralogical and geochemical data, the Gano deposit formed in an oxidized environment under warm-humid climates, significantly linked to rainfall seasonality and groundwater-level fluctuations. Gallium, Nb, and V median values of the Gano bauxite ores are a bit above the maximum value of these critical metals in the northwestern Iranian and Alborz bauxite data set, making diaspore-, anatase-, and hematite-rich layers and lenses valuable for further exploration of these critical metals.

Stratigraphic and volcanic signatures of Miaolingian-Late Ordovician rift pulses in the Alborz Mountains, northern Iran

• The Cambrian-Ordovician succession of the eastern Alborz Mountain Range displays uplift episodes associated with erosion. • The SPICE chemostratigraphic shift marks the Miaolingian–Furongian boundary. • Alkaline to subalkaline magmatic activities are separated by quiescent intervals of up to 35 m.y. • Intraplate (continental rift) volcanism reflects OIB-type mantle sources . • Plume-related rift pulses are linked to a large igneous province about 600 km across. Recent reconnaissance geological mapping, identification of unconformities and chronostratigraphic dating of Miaolingian to Ordovician strata in the eastern Alborz Mountains have led to recognition of synsedimentary uplift episodes associated with block tilting and partial erosion of the Cambrian Mila and Ordovician Simeh Kuh, Qumes and Lashkarak formations. A chronostratigraphic revision of the Miaolingian-Late Ordovician fossil content is presented, and the Steptoean Positive Carbon Isotope Excursion (SPICE) chemostratigraphic shift, marking the Miaolingian–Furongian boundary, is constrained close to the Members 2/3 contact of the Mila Formation. Upper Ordovician basaltic lava flows embedded in the Abarsaj Formation and Devonian sills and dykes intruded in the Mila and Simeh-Kuh formations were geochemically analysed and compared with the voluminous lava eruptions recognized in the Katian-Llandovery Soltan-Maidan and Gorgan Schists formations, and in the ?Emsian-Eifelian Mighan Formation. They represent successive magmatic pulses of alkaline to subalkaline activities, separated by background (quiescent) intervals of up to 35 m.y., characterizing an intraplate field (continental rift) affinity compatible with OIB-like (ΔNb greater than 0) mantle sources. Successive Miaolingian-Mid Ordovician (volcanic-free) uplift episodes were related to lithospheric doming preceding the onset of stepwise plume-related rift pulses, which shaped a large igneous province with transects of about 600 km, linking the Damghan and Alestan domains of the eastern Alborz Mountains with South Kopet-Dagh and some blocks of Central Iran.

Movements of a male greater spotted eagle (Clanga clanga) during its 2nd and 3rd calendar years

Abstract The greater spotted eagle (Clanga clanga) is poorly known compared to other European eagles. We tracked an immature greater spotted eagle during 2018–2020 within the eastern European part of the species’ distribution, west of the Ural Mountains. Because so little is published about the annual movements of this species, especially from that region, tracking data from this single individual are valuable. 95% kernel density estimator (KDE) range sizes for the two complete winters in Yemen were 4,009 km2 (2018), 1,889 km2 (2019); 95% dynamic Brownian bridge movement models (dBBMM) encompassed 1,309 km2 (2018) and 1,517 km2 (2019). It returned to the same wintering area every year. During summer 2018, it settled into a small area (95% KDE = 126 km2; 95% dBBMM = 21 km2) near Birsk, eastern European Russia; in 2019 it wandered over a huge area (95% dBBMM = 66,304 km2) of western Kazakhstan and southern Russia, south west of Yekaterinburg. Spring migration 2018 was west of the Caspian Sea; during 2019 it was east of it. Mean speed of spring migration was 160±120 km/day during 2018, and 132±109 km/day during 2019. Autumn migration passed east of the Caspian in both years, and the mean speed of migration was 62 ± 78 km/day in 2018, and 84 ± 95 km/day in 2019. During both spring and autumn migrations, the eagle made stopovers, mostly lasting 1–2 days. The eastern Alborz Mountains in northeastern Iran appeared to be an important stopover locale, where autumn stopovers lasted 19 days (2018) and 27 days (2019). These and other data suggest that most greater spotted eagles that spend summers west of about 42°E, winter in southern Europe, Asian Turkey, the Levant and Africa, and those that summer to the east of that meridian winter in southern Asia, including Arabia.

Calcareous nannofossil biostratigraphy and paleoenvironment of the Dalichai (Lower Cretaceous) Formation (Talu Section) in eastern Alborz Mountains, northern Iran

Calcareous nannofossil biostratigraphy and paleoenvironment of the Dalichai (Lower Cretaceous) Formation (Talu Section) in eastern Alborz Mountains, northern Iran

The first Early Ordovician graptolites and marine incursions in eastern Alborz, Iran

AbstractGraptolites have been collected from sections through Lower Ordovician strata in northern Iran. At the Saluk Mountains, in the Kopet–Dagh region, mudrocks yielded fragmentary tubaria ofRhabdinoporasp. cf.R. flabelliformis, indicating the presence of lower Tremadocian strata there; stratigraphically, they lie between two limestone beds with the euconodontCordylodus lindstromi. At Simeh–Kuh in the eastern Alborz Mountains (Semnan Province), upper Tremadocian – lower Floian strata include laminated dark mudstones that contain restricted graptolite faunas, mainly of small declined didymograptids; these are thought to represent incursions of plankton during periods of marine highstands. The lower major flooding surface in Simeh–Kuh coincides with an invasion of the graptolite biofacies and an incursion ofHunnegraptus? sp.; the second major flooding surface is associated with an incursion ofBaltograptus geometricus. They were most probably synchronous with those in the lower part of theHunnegraptus copiosusBiozone and at the base of theCymatograptus protobalticusBiozone in the of the Tøyen Shale Formation succession of Västergötland, Scandinavia, suggesting that observed characters of sedimentation were eustatically controlled.

Fan morphology evidence on Late Quaternary deformation in the southern front of the Central and Eastern Alborz Mountains in the Eyvanekey, Garmsar, Semnan areas, Northern Iran

Although numerous studies have been done on the Alborz Mountains, few have examined Quaternary events based on alluvial fans which are located in front of the southern limb of the Central and Eastern Alborz Mountains. This study analyzed the morphometric indexes for 131 alluvial fans (three generations) in the Eyvanekey, Garmsar, and Semnan areas (As, WLF, Bull, Fa, Fs, Fg, Fc, R) as well as for basins (Da, AF, T, Bs), mountain fronts (Fmf, Smf, Vf, Fd), and rivers (Sl). The morphometry results show that a young deformation in this area has caused on uplift in the crust along structures in the Alborz. The Garmsar area is more active than the Semnan area in which both are more active than the Eyvanekey area. All of the alluvial fan evolution in this area relate to the Quaternary events. The study on the information obtained from the exploitation wells and geoelectric profiles of the region shows that the Alborz uplift in the north is associated with the erosion and deposition of the new deposits in the form of alluvial fans. The bedrock behavior at the base of the fans has a direct effect on the formation of the second- and third-generation fans. The effect of the continual compressional tectonics in the Late Quaternary is associated with the uplifting evaporite masses, the uplifting hanging walls of the reverse faults, and the growth of the folded structures.

Alborz Heritage: geographic distribution and genetic differentiation of the Iranian Paradactylodon (Amphibia: Hynobiidae)

Abstract Paradactylodon, a genus of Hynobiidae, is distributed in mountainous regions of the Middle East. This genus comprises three species, Paradactylodon mustersi (Afghanistan), Paradactylodon persicus, and Paradactylodon gorganensis (Iran). Initially, P. persicus was reported from Talysh Mountains, and afterward, P. gorganensis was described from the eastern Alborz Mountains. Although these two Iranian Paradactylodon species were distinguished based on morphological features, there are arguments about their systematic status. In this contribution, 30 samples of hynobiid salamanders were collected from Talysh and Alborz Mountains and the phylogenetic relationship between the two species was assessed using two mtDNA markers (COI and 16S). Additionally, in order to survey the potential habitat suitability for the species, Species Distribution Models (SDMs) were performed and projected on climate scenarios that reflect current and past (6 ky and 21 ky before present) conditions. Our results indicated that P. gorganensis is nested within P. persicus. Overall, both SDM and molecular analyses suggest that the Iranian Paradactylodon population was affected by the Quaternary glacial period, and according to haplotype networks, haplotype diversity was higher in the western part of the distribution range of the species. Given the low genetic distance among all samples, we suggest P. gorganensis be synonymized with P. persicus. Considering the conservational values and numerous threats that this endemic species is facing, we encourage a revision of the IUCN Red List category of the species immediately.

Biostratigraphy of Devonian-Carboniferous boundary in Tuyeh-Darvar section, north of Iran

Devonian-Carboniferous boundary is not clear in the Eastern Alborz Mountains. In the current study Tuyeh-Darvar section with about 170 m, thickness is selected. In this investigation, the primary goal is revision of Devonian/Carboniferous Boundary (known as DCB) and the other goal is the redefinition of the DCB as a famous necessity (based on ICS program in 2008 for defining the boundary and to find a new GSSP). According to Conodont data from acid-leaching 53 carbonate samples(by acid acetic) that obtained from Late Devonian and Early Carboniferous deposits in this section, and based on standard conodont Zonation 6 Zone are recognized;1. Bi.ultimus/or Si.praesulcata Zone, 2. Pr.kockeli /or Si.sulcata Zone, 3. Si.duplicata to Si.sandbergi bio interval, 4. Si.crenulata Zone, 5.Gnathodus-P.inornatus Zone, and 6.Ps.multistriatus Zone. Considering to the Conodont Zones above mentioned, Conodont faunas and other evidences, in the Tuyeh-Darvare section the DCB, is located within cream to grey silt stone beds, which are lies between K6 limestone and K8 dark carbonate beds (about 7.10 m above the base of recent studied section).

Paleoenvironmental control on trace fossils across a Mississippian carbonate ramp succession, Mobarak Formation, east of Central and Eastern Alborz, Iran

The Lower Carboniferous Mobarak Formation in the east of Central and Eastern Alborz Mountains, northern Iran, is deposited on a distally steepened carbonate ramp. Detailed facies analysis allowed to differentiate seven facies associations, includes deep marine basinal (FA1), toe-of-slope/outer ramp (FA2), ramp/slope (FA3), shallow open marine (FA4), bioclastic bars or shoal (FA5), lagoon (FA6) and intertidal flat (FA7). The trace-fossil suites of the studied successions are shown for the first time. Twenty eight ichnogenera were identified, i.e. Arenicolites, Asterosoma, Bergaueria, Chondrites, Cochlichnus, Diplocraterion, Halopoa, Helminthopsis, Helminthorhaphe?, Helminthoidichnites, Gordia, Gyrochorte, Lockeia, Mammilichnis, Megagrapton, Nereites?, Palaeophycus, Phycodes, Phycosiphon, Planolites, Protovirgularia, Rhizocorallium, Rosselia, Sinusichnus, Skolithos, Taenidium, Thalassinoides, and Zoophycos. The seven facies associations deposited in a wide range of physico-chemical conditions, show distinct proximal to distal trends. As a result of oxygen-depleted depositional conditions, only the tracemakers of Zoophycos survived in deep marine slopes, which were close to turbiditic sedimentation zones. The development of a benthic community under the stable condition and a long-term colonization window were documented by highly diverse suites of the Cruziana ichnofacies. Under a stressed environment (after tempestite deposition), the Skolithos ichnofacies displayed a low diversity of opportunistic ichnocommunity suite. The mixed Skolithos–Cruziana ichnofacies occur in the middle to distal lower inner ramp. The identification of the archetypal ichnofacies may document broad changes of environmental parameters such as variability in sedimentation rates, energy level, salinity, substrate properties/consistency, nature of nutrient supply and dissolved oxygen content. Relationships among different modes of ethology of tracemakers and sedimentary structures in the studied successions are used to clarify sedimentary conditions.

Little Known Darkling Beetle Blaps scabiosa Baudi di Selve, 1874 (Coleoptera, Tenebrionidae: Blaptini): Taxonomy, Morphology, and Distribution

The tenebrionid species Blaps scabiosa (tribe Blaptini) is redescribed and illustrated. This species was twice described under the same name by Baudi di Selve in 1874 from Tashkent (now Uzbekistan) and by Faust in 1875 from Tash (Iran, Semnan Province). In 1876 Faust synonymized his species with Baudi’s species. Nabozhenko interpreted these taxa as two distinct species and gave a new name B. neoscabiosa Nabozhenko, 2008 to the Iranian B. scabiosa Faust, 1875 to eliminate homonymy. This species has never been found in Tien Shan and occurs only in Eastern Alborz Mountains. The type locality “Tashk.” (Tashkent) should be corrected to “Tash” (Iran, Semnan). After examination of the type specimens we have established that the Baudi’s and Faust’s taxa are conspecific, and the following synonymy is proposed: Blaps scabiosa Baudi di Selve, 1874 = B. scabiosa Faust, 1875, syn. resurr. = B. neoscabiosa Nabozhenko, 2008, syn. n. The lectotype of Blaps scabiosa Faust, 1875 is designated.

Predicting the impacts of climate change on the distribution of Juniperus excelsa M. Bieb. in the central and eastern Alborz Mountains, Iran

In recent years, global climate change has had significant biological, temporal, and spatial effects on many terrestrial habitats. The objective of this study was to evaluate the effect of climate change on the geographic distribution of Juniperus excelsa and prioritize its habitats for protection against these effects until 2070. The study was conducted using the MaxEnt species distribution model and two data series GFDL-CM3 and MRI-CGCM3 under scenarios RCP2.6 and RCP4.5 of the 5th IPCC report. Our results revealed that elevation, minimum temperature of coldest month, precipitation of coldest quarter, annual mean temperature, and slope aspect, in that order, have the greatest effects on the species’ distribution in the study area. Under optimistic scenario RCP2.6, both models predicted that the species’ presence area will grow, but under RCP4.5, models predicted that by 2070, some parts of its habitat in western and central heights will be lost because of change in climate parameters like minimum temperature of coldest month and precipitation of coldest quarter. Under the latter scenario, the northeastern parts of the study area showed no changes in terms of climatic parameters and climatic niche. The results of both climate data series indicated that the Juniperus excelsa will slowly migrate to higher elevations to cope with the changing climate. Assessment of the results through field studies showed that outputs of GFDL-CM3 are closer to the reality.

Organic geochemistry of the Upper Triassic–Middle Jurassic Shemshak Group (Alborz Mountains, NE Iran)

The organic geochemistry of shale samples of Shemshak Group at Dehmolla section in Eastern Alborz Mountains in the present study are discussed throughout the Rock-Eval pyrolysis. The results used to describe the quantity, type, maturity, and petroleum potentials of the Shemshak Group sediments. The pyrolysis data show that the total organic carbon values of the shale samples are between 0.08 and 20.98 wt% and the generation potential (S1+ S2) of the studied samples ranges from 0.02 to 9.47 mg HC/g rock revealing the organic richness of these samples varies from poor to good. The type of hydrocarbon products (S2/S3) ranging from 0.06 to 2.33 and the type of hydrocarbon determined from Tmax versus HI indicate mainly well for gas generation. Based on the HI versus OI plot diagram, the type III of kerogen is the main type of organic matter in studied samples. These data also show that most of the samples were deposited in oxic environments with low sedimentation rate and high amount of organic matter from the terrestrial source. “Tmax” values ranging from 416 °C to 602 °C in studied samples indicate that most of the samples are over mature and located in gas zone.

Neolithic developments in the Gorgan Plain, south-east of the Caspian Sea

Until about two decades ago, the Neolithic of north-east Iran was known only from a few brief excavation reports: the sites of Yarim Tappeh (Stronach 1972) and Turang Tappeh (Deshayes 1967) on the Gorgan Plain, and preliminary reports of large-scale excavations at the twin mound of Sang-e Chakhmaq in the southern foothills of the eastern Alborz Mountains (e.g. Masuda 1984). In the absence of absolute chronologies, these sites were dated by ceramic assemblages to the sixth millennium BC, and were considered to relate to the so-called ‘Jeitun Culture’ of southern Turkmenistan (Figure 1; Roustaei 2016a).

Drymocallis damghanensis(Rosaceae), a New Species from Iran

Drymocallis damghanensis Naderi & Faghir (Rosaceae) is described as a new species. The specimens were collected during a floristic study of an unexplored area on the rocky slopes of the Eastern Alborz Mountains (Damghan, Iran). Drymocallis damghanensis can be distinguished by its hairy carpels and rounded-obtuse teeth in leaflets. Here it is compared with the morphologically most closest taxa D. poteriifolia and D. schiraziana.

The World’s second oldest strophomenoid-dominated benthic assemblage in the first Dapingian (Middle Ordovician) brachiopod fauna identified from Iran

Rocks previously mapped as Devonian at Gerd-Kuh in the Eastern Alborz Mountains of Iran have yielded Middle Ordovician faunas including the brachiopods described here, the first rhynchonelliform brachiopods of Dapingian age ever described from Iran. The shells described are defined as a new Dirafinesquina Benthic Association, and which is the second oldest strophomenoid-dominated assemblage from anywhere in the World. There are six brachiopods, three of which are newly named as the strophomenoid Dirafinesquina antiqua sp. nov., the orthoid Zhanorthis gerdkuhensis gen. et sp. nov., and the porambonitoid Eoporambonites raziabadensis sp. nov.

Inclined transpression in the Neka Valley, eastern Alborz, Iran

Three major nappes in the Neka Valley in the eastern Alborz Mountains of Iran allow the Cimmerian to present convergence following the oblique collision between Iran and the southern margin of Eurasia. This work reports the identification of an inclined transpression zone recognized by field investigations and strain analyses of the geometries of formations and detailed mesoscopic structural analyses of multiple faults, folds and a cleavage. The main structures encountered include refolded recumbent asymmetric fold nappes, highly curved fold hinges, in a transpression zone that dips 37° to the NW between boundaries thrusts striking from N050° to N060°. The β angle (the angle between the zone boundary and direction of horizontal far-field shortening) is about 80°. The north-west and south-east boundaries of this zone coincide with the Haji-abad thrust and the Shah-Kuh thrust, respectively. Fold axes generally trend NE–SW and step to both right and left as a result of strike–slip components of fault displacements. Strain analyses using Fry’s method on macroscopic ooids and fusulina deformed into oblate ellipsoids indicate that the natural strain varies between 2.1 and 3.14. The estimated angle between the maximum instantaneous strain axis (ISAmax) and the transpression zone boundary (θ′) is between 6° and 20°. The estimated oblique convergence angle (α), therefore, ranges between 31° and 43°. The average kinematic vorticity number (W k ) is 0.6, in a zone of sinistral pure shear-dominated inclined triclinic transpression. These results support the applicability of kinematic models of triclinic transpression to natural brittle–ductile shear zones.

A lower Viséan (Carboniferous) brachiopod fauna from the eastern Alborz Mountains, northern Iran, and its palaeobiogeographical implications

AbstractThe brachiopods from the upper part of the Mobarak Formation at the Kiyasar section in the eastern Alborz Mountains, northern Iran, have been studied in detail. Fifteen species assigned to 13 genera of Strophomenida, Orthotetida, Orthida, Productida, Athyridida and Spiriferida are described. The fauna is determined as early Viséan in age based on the presence of Eomarginifera paucispinosa, Grandispirifer mylkensis and Unispirifer sp., and their associated foraminifers Uralodiscus, Paraarchaediscus, Glomodiscus and Endothyra, though taxa ranging through the Tournaisian–Viséan are also present. A comparison of its palaeogeographical affinities with other faunas show that the Alborz brachiopod fauna maintains strong Palaeotethyan affinities based on its general similarities with those of Eurasia, North America and Australia. This is suggestive of a prevailing oceanic current that circulated between the northern and southern shelf sea of the Palaeotethys Ocean, with which the warm‐water brachiopod taxa were widespread in the Palaeotethyan Realm through the early Viséan. Copyright © 2016 John Wiley & Sons, Ltd.

Short- and Long-Term Development of the Miankaleh Spit, Southeast Caspian Sea, Iran

Kakroodi, A.A.; Kroonenberg, S.B., and Naderi Bonab, M. 2014. Short- and long-term development of the Miankaleh Spit, southeast Caspian Sea, Iran.The development of the 60-km-long Miankaleh Spit in the southeastern corner of the Caspian Sea has been studied in two different timescales. At the start of the twentieth century 3 m sea-level cycle, the spit already existed, but it emerged prominently during the lowstand in the late 1970s, and drowned and fell apart into several islands during the following highstand that culminated in 1995. The analysis of core data and sedimentological analyses (grain size, biofacies, carbonate content, heavy mineral, and magnetic susceptibility) show that the Miankaleh Spit and the Gorgan Bay did not yet exist during the well-known 2600–2300 cal. YBP highstand, and at that time waves and longshore currents deposited barrier systems along the mainland coast. During the lowstand, deltas from rivers draining the eastern Alborz Mountains extended much more westward than at present. It was only during the last major highstand in the Little Ice Age that the present-day Miankaleh Spit was formed by eastward progradation caused by strong longshore currents.

Some rugose corals from the Devonian (Givetian and Frasnian) of Northeastern Iran

A rugose coral fauna from Givetian and Lower Frasnian strata of the Khoshyeilagh Formation in the Eastern Alborz Mountains (Northeastern Iran) was studied. In total, eight species belonging to five genera are reported from the Mighan section, northeast of the city of Shahrood. From the Givetian, four species of the genera Spinophyllum Wedekind, 1922, Chostophyllum Pedder, 1982, and Aristophyllum Bulvanker, SPaSSky & kravtSov, 1975, are described. From the overlying Lower Frasnian, four species are recorded, belonging to the genera Sinodisphyllum Sun, 1958 and Charactophyllum SimPSon, 1900.

Lithostratigraphic revision of the middle Cambrian (Series 3) and upper Cambrian (Furongian) in northern and central Iran

Studies of stratigraphic sections of Cambrian rocks exposed in the central and eastern Alborz Mountains and in the Tabas area indicate characters that demand a revision of the upper Lower Cambrian (Series 2-Series 3 boundary interval) through lowermost Ordovician lithostratigraphy of northern and central Iran. Emended units include the Lalun and the (traditional) Mila Formation, the latter now being subdivided into the Fasham Formation (new; formerly White Quartzite, Top Quartzite, or Basal Quartzite), the Deh-Sufiyan Formation (new; essentially equivalent to the informal members 1 and 2 of the traditional Mila Formation), the Deh-Molla Formation (new; essentially equivalent to the informal members 3 and 4 of the traditional Mila Formation). Together with the lower Ordovician Lashkerak Formation and an unnamed formation, these formations constitute the Mila Group. Correlation of these lithostratigraphic units within Iran and intercontinentally are discussed with respect to both biostratigraphic and sequence stratigraphic data. It is obvious that the Lalun Formation records not only a (sub)globally recognisable regressive event towards the end of the Early Cambrian, but, in association with the Fasham Formation, also provides evidence for the subsequent earliest Middle Cambrian transgression that finally led to the establishment of a carbonate platform that persisted throughout the remainder of the Cambrian Period, generating the deposits of the Deh-Sufiyan and Deh-Molla formations of the Mila Group.