Central Alborz Research Articles

COI Barcodes combined with multilocus data for representative Aporia taxa shed light on speciation in the high altitude Irano-Turanian mountain plateaus (Lepidoptera: Pieridae)

Even though the high plateaus of Qinghai-Tibet and Iran share many faunal elements, the historical biogeography of the species present in this area are not very well understood. We present a complete COI barcode library for Aporia Hübner and a first comprehensive phylogeny for the genus including all known species and majority of subspecies using ten available genes (COI-COII, ND1, ND5, Cytb, EF-1a, Wg, 16S, 28S-D2/D3 and 28S-D8). We then focus on A. leucodice (Eversmann, 1843) and related taxa in order to resolve some long-standing taxonomic issues in this species-group. Based on DNA sequence data as well as morphology, we raise Aporia illumina (Grum-Grshimailo 1890) stat. nov. (= pseudoillumina Tshikolovets 2021 syn. nov.) as a distinct species and designate a lectotype; synonymize Aporia leucodice leucodice Eversmann, 1843 (= A. l. morosevitshae Sheljuzhko, 1908 syn. nov.); and describe a new species, Aporia ahura sp. nov., from the Central Alborz Mountains in northern Iran.

Spontaneous growth of plants enhances phytoextraction on abandoned coal mine wastes in Central Alborz coalfield, Iran

Coal mining disperses heavy metals into the environment, necessitating the identification of metal-tolerant plants for ecosystem restoration. This study evaluated the phytoremediation potential of plant species in abandoned coal wastes in northern Iran. Pollution indices indicated moderate contamination of Cu, Ni, V, Zn, Pb, Cr, and As in coal wastes. The plants varied in their ability to accumulate and translocate these metals, with most showing efficient root-to-shoot translocation. Artemisia scoparia (41.06 mg.kg−1) and Capparis spinosa (42.48 mg.kg−1) were effective for Cu phytoextraction. Most species, notably Cynodon dactylon (3.4 mg.kg−1), showed promise for phytoextraction of Cr. Capparis spinosa (7.67 mg.kg−1) exhibited potential for Pb phytoextraction. Most plants, particularly Hordeum vulgare and Melica persica, were effective phytoextractors of Ni. Sylibum marianum accumulated V beyond phytotoxic levels. Chenopodium album and Glaucium fimbriligerum were identified as phytoextractors of Zn while Cynodon dactylon and Hordeum vulgare, accumulating >100 mg.kg−1 Zn in roots, showed potential for phytostabilization. Sylibum marianum and Glaucium fimbriligerum, acted as excluders for As. Kochia prostrata and Artemisia aucheri were excluders for Cu, Cr, Ni, and Pb. This study provided the role of multiple indigenous plants, including perennials and annuals with diverse life forms, in metal extraction and stabilization for sustainable coal waste management.

Provenance of mixed volcaniclastic-carbonaticlastic gravity-flow deposits: a case study from the Cretaceous of the southern Central Alborz (Iran)

ABSTRACT Understanding the petrographic and geochemical characteristics of different tectonic settings is essential to improving traditional methods of identifying the provenance of palaeo-sedimentary environments. This research focuses on the K2b unit, which consists of mixed carbonate and volcanic lithic sandstones located in Iran with the age of the Turonian-Early Campanian period. Five sedimentary lithotypes with distinct petrographic and geochemical signatures were identified in the Turonian/Lower Campanian K2b unit, which consists of coarse-grained fan-delta strata. Carbonate and volcanic lithic fragments are the most characteristic components of mostly quartzo-lithic to felspatho-litho-quartzose sandstone layers, documenting a unidirectional paleocurrent pattern with the north-eastward direction. The original composition has undergone diagenesis, resulting in the precipitation of authigenic carbonates and depleting Rare Earth Elements (REE) except for Eu, which shows a positive anomaly. The K2b fan delta was situated on the margin of the proto-south Caspian back-arc basin, and the sediments were sourced from the undissected magmatic arc. The gravity flow deposits in the K2b unit were likely triggered by tectonic activity in the catchment area of the fan delta, leading to uplift and formation of relief associated with the regional Mosha Fault and, on a larger palaeogeographic scale, with subduction of the Arabian plate beneath the Iranian plate during Turonian-Early Campanian.

A botanical expedition in Eastern Alborz (Iran): rare plant species and assessing their conservation status

This study is a part of an ongoing floristic study in Eastern Alborz mountain range (Iran). The flora and vegetation of this area are less known compared to those of Central Alborz. The study area indicates the regionally significant connection between the Kopet Dagh-Khorassan and Central Alborz. A total of 41 rare-threatened taxa belonging to 26 genera and 15 families are presented. According to the IUCN criteria, our checklist identifies 3 taxa classified as Critically Endangered (CR), 19 taxa as Endangered (EN), 4 taxa as Vulnerable (VU), 4 taxa as Near Threatened (NT), 3 taxa as Least Concern (LC), and 8 taxa as Data Deficient (DD). Among them, 28 are hemicryptophytes, followed by chamaephytes (7 species), geophytes (4 species), and therophytes (2 species). During 10 years of field investigations on the semi-arid areas of Eastern Alborz, some rare-threatened endemic species have been rediscovered in the region. Geographic distribution maps of all rare species together with the accompanying species and their conservation status were drawn up. It is noteworthy that some rare species are known only from their locus classicus and no new specimens have been collected during the last 30 to 80 years. A total of 10 taxa were reported for the first time from Eastern Alborz, primarily exhibiting a disjunct distribution pattern occurring in the high elevations of Zagros, Alborz and/or other mountain ranges in SW Asia.

A history of explosive eruptions at Young Damavand volcano, Iran

Young Damavand volcano is a steep isolated volcano in the Central Alborz Mountains, Iran, that is characterized by extensive lava flows and pyroclastic successions and is placed on the eroded remains of Old Damavand. Pyroclastic fall and density current deposits on all flanks of the volcano were sampled and studied. From a tephrostratigraphic and geochemical study of the proximal-medial sequences, 14 phases of explosive volcanic activity are identified, characterized by a combination of ash and pumice fall deposits, and/or dense and dilute pyroclastic density current deposits. Some explosive phases of Damavand are thought to have happened one after the other with only short time intervals, since almost no traces of paleosol can be identified between them. We also show that the intensity of the eruptions varied between different phases, confirmed by relative thickness and grain size of the different fall deposits and their distance from the crater. The evidence of numerous explosive eruptions, five of which with Volcanic Explosivity Index 4 in the history of the activity of Young Damavand volcano, shows the importance of assessing its potential volcanic hazards.

Unravelling the tectonic phases: The impact of the South Caspian Block on Late Cenozoic deformation in the Central Alborz, Iran

Paleostress reconstruction through polyphase fault-slip data of a multi-deformed region suffered collisional tectonics can lead to detecting the stress phases. Based on earthquakes’ focal mechanisms and morphotectonic features, multiple deformation phases model has been proposed for the Alborz Mountains located in the collision zone between the Arabian (Central Iran) and Eurasian (South Caspian block) plates during the Late Cenozoic. In this study, paleostress analysis has been carried out in an area bounded by two (Kandovan and Taleghan) regional faults in the Central Alborz Mountains using fault-slip data. This analysis resulted in the identification of three main tectonic phases. The first, compressional phase is proposed to cause the inversion of the Alborz Mountains’ major initial normal faults to reverse faults during the convergence of the Arabian and Eurasian plates. The second, transpressional phase is offered as a factor for the reactivation of the hidden Alborz basement faults to form the NE-striking left-lateral strike-slip faults on the sedimentary cover. The third, transtensional phase is suggested to be responsible for the development of the NNE–SSW left-lateral transtensional faults. It is proposed that the second and third paleostress phases are affected mainly by the indentation of the South Caspian Block into the Alborz Mountains during the Late Cenozoic.

Using satellite-derived land surface temperatures to clarify the spatiotemporal warming trends of the Alborz Mountains in northern Iran

The Alborz Mountains are some of the highest in Iran, and they play an important role in controlling the climate of the country’s northern regions. The land surface temperature (LST) is an important variable that affects the ecosystem of this area. This study investigated the spatiotemporal changes and trends of the nighttime LST in the western region of the Central Alborz Mountains at elevations of 1500–4000 m above sea level. MODIS data were extracted for the period of 2000–2021, and the Mann–Kendall nonparametric test was applied to evaluating the changes in the LST. The results indicated a significant increasing trend for the monthly average LST in May–August along the southern aspect. Both the northern and southern aspects showed decreasing trends for the monthly average LST in October, November, and March and an increasing trend in other months. At all elevations, the average decadal change in the monthly average LST was more severe along the southern aspect (0.60°C) than along the northern aspect (0.37°C). The LST difference between the northern and southern aspects decreased in the cold months but increased in the hot months. At the same elevation, the difference in the lapse rate between the northern and southern aspects was greater in the hot months than in the cold months. With increasing elevation, the lapse rate between the northern and southern aspects disappeared. Climate change was concluded to greatly decrease the difference in LST at different elevations for April–July.

Structure and kinematics of active faulting in the northern domain of Western and Central Alborz, Iran and interpretation in terms of tectonic evolution of the region

Field evidence, seismicity, and geodetic data are combined to define the tectonic evolution along the northern domain of the Western and Central Alborz ranges, which have experienced significant earthquakes. One of our main focuses is to present the geometric-kinematic characteristics of active fault planes in the North Alborz fault zone and its subsidiary faults as a basis for seismic hazard assessment. To evaluate the seismotectonics in the region, three active segments of the seismic zone are identified. These segments primarily exhibit reverse mechanisms and left-lateral strike-slip components and act as the boundaries of neotectonic stress domains around the transition zone between Alborz and the South Caspian Basin. The spatial distribution of the strike-slip and dip-slip faulting over the Western and Central Alborz range supports our understanding of the geodynamic processes of the region. Our map of local active faults reveals five main systems with N–S, NE–SW, ENE–WSW, E–W, and NW–SE directions. Field studies indicate that strike-slip movements predominate and are consistent with a ∼WNW-ESE-oriented left-lateral wrench system. Pure left-lateral strike-slip faults trending E-W, extensional faults trending NE–SW, and compressional faults trending NW-SE are identified. Regional field investigations reveal spatial variations in the fault zone width of the northern domain of the Western and Central Alborz. The findings demonstrate that fault zone structures and their spatial distribution along the width of the area are strongly affected by the strain partitioning process in the transpressional zone. A spectacular well-exposed transpressional zone from the Western and Central Alborz region is described in detail, where outer domains are faults with a dominant reverse mechanism, and the inner domain is a wrench zone that includes faults with a dominant strike-slip mechanism. The seismic activity in the Northern Alborz region is mainly concentrated along the North Alborz fault zone and its subsidiary fault planes, of which some are identified for the first time in this research. Significant seismic events have occurred at locations where these newly identified fault planes interact. The maximum values of the geodetic strain axes in Western and Central Alborz are consistent with the area of high seismicity.

Evaluating the ecological security of ecotourism in protected area based on the DPSIR model

Evaluating the ecological security of ecotourism (EES) in protected areas is critical because these areas play a vital role in protecting biodiversity and natural resources. This study evaluated the EES status of Central Alborz Protected Area (Northern Iran), based on a Driver, Pressure, State, Impact, and Response (DPSIR) model. We developed a comprehensive list of 59 indicators for the DPSIR model and employed an Analytical Network Process (ANP) model to determine indicator weights harnessing the opinion of experts on which indicators are most influential. This approach facilitated the identification of regions with the highest EES vulnerability, notably in the northern and western sectors of our study area along the boundary between Tehran and Mazandaran provinces. Here, the mechanisms that drive EES change the most include ecotourism activities, livestock overgrazing, and uncontrolled physical and economic activities, along with extensive road and highway development, and land use and land cover changes. Indicators that are most effective for determining the EES status, include physical and economic activities. We conclude by discussing indicators to respond to the increasing threat to EES in Protected Areas such as the involvement of government in strategic integrated management. Our study serves as a methodological blueprint on how to evaluate the EES of Protected Areas.

Thalassinoides horizontalis Myrow, 1995 from the Middle-Upper Ordovician shallow marine siliciclastics of Iran (Lashkerak Formation)

Thalassinoides Ehrenberg, 1944 are relatively common bioturbational structures in carbonate shallow marine successions from the early Paleozoic. Much rarer is the reference to this ichnogenus in siliciclastic formations from the same age. In the Ordovician Lashkerak Formation cropping out at the Central Alborz mountains, Iran, Thalassinoides is a common trace fossil in wave-dominated shoreface complex and prodelta-mouth bar environments of a fluvial-dominated delta. We compare the Middle-to-Upper Ordovician branching networks of the Unit 2 of the Lashkerak Formation with the ichnospecies Thalassinoides horizontalis Myrow, 1995 emphasizing the almost entire bedding-parallel orientation, regular branching and lack of constrictions and swellings. The eodiagenetic halos developed from mucus-lining walls, or by change of the original sediment fabric, typical of this and other ichnospecies of Thalassinoides in carbonate settings are not found in sandstones. The almost polygonal mazes from the Lashkerak Formation are also compared with the recently erected Protopaleodictyon aitkeni Morgan, Henderson & Pratt (2019), considered as a giant graphoglyptid in an early evolutionary stage of these forms in shallow marine environments. Both trace fossils are similar in morphology, size, preservation, ichnofacies and interpreted function, thus being P. aitkeni a junior synonym of Thalassinoides horizontalis.

Assessing the quality of bee honey on the basis of melissopalynology as well as chemical analysis.

Melissopalynological and chemical analysis of honey provide us useful and valuable information about the botanical and geographical origin of honey. The data in question is very important for authentication as well as for testing the quality of honey, so this is considered the main method in honey regulation here, we have used chemical analysis and melissopalynology to evaluate different honey samples from two main Iranian hubs of honey. Sampling was carried out on two important poles in Iran's honey production, the central Alborz region, and the mountainous Zagros ecosystems in the years 2020 to 2021. Therefore, 52 samples from Alborz (Northern Iran), as well as 42 samples from the Zagrosian ecosystems (western Iran) belonging to different ecological habitats, were collected. In addition, samples were taken at 7 altitudes from 0 to 3500 m a.s.l. Furthermore, in this study, various chemical analyses such as the effect of antioxidant activity, the amount of total phenolic content, pH, and moisture content of honey samples were evaluated. Our results showed that all honey samples were classified as polyfloral honey. Based on our findings, 57 honey samples (61%) contained the standard amount of pollen. A total of 42 plant families and 55 genera were identified in the studied samples, with the highest presence of Asteraceae, Fabaceae, Rosaceae, Apocynaceae, and Apiaceae. Finally, an antioxidant activity ratio of 19% to 98%, total phenolic content from 0.08 to 0.51 ppm, pH from 1.90 to 5.21, and moisture content from 13% to 18.40%.

Evaluating the influence of recent tectonic activity on the river evolution using the identification of knickpoints in the south of Central Alborz Belt

Evaluating the influence of recent tectonic activity on the river evolution using the identification of knickpoints in the south of Central Alborz Belt

Interaction between tectonics, plutonism and mineralization of the Duna Pb-Ba ore deposit regarding fluid inclusion study (Central Alborz, Iran)

This article discusses the impacts of overprinting of tectonic and plutonic events on the mineralization of the Duna Pb-Ba ore deposit, according to geologic settings and fluid inclusion studies. The Duna carbonate-hosted deposit contains a significant amount of Ag (18.9–264.3 ppm ), Cu (77–41600 ppm), Sb (32.7–11000 ppm), Sr (63.5– 15100 ppm), and Fluid inclusions with 7.34–23.65 wt.% NaCl equivalent. The homogenization temperature of about 110–285°C, as well as the paragenesis of the minerals shows a difference compared with other Pb-Zn deposits such as the Irish-type and MVT. The ore mineralization in the Duna mine occurred as stratabound, open space-filling, and along the brecciated fault zones. The concordant (stratabound) type of mineralization, with salinity and homogenization temperature of 18.54 to 23.65 wt.% NaCl equivalent, and 113°C to 165°C respectively, is usually typical of MVT-ore deposits, which in this area evolved during the Early Cimmerian orogeny and was later interrupted by mineralization along younger brecciated fault zones with salinity and homogenization temperature of 7.34 to 23.65 wt.% NaCl equivalent, and 113°C to 285°C respectively. This discordant mineralization, which occurred along the faults, formed by the end of the Late Cretaceous and during the Cenozoic as a result of the intrusion of a plutonic mass, and is comparable to the Irish-type ore deposits.

Geochemistry of uranium and REEs in Dalir phosphate deposit, Central Alborz zone

کانسار فسفات دلیر در 57 کلیومتری جنوب غربی شهر چالوس در استان مازندران و زون البرز مرکزی دارد. میزبان این ذخیره سازند سلطانیه است که یکی از مهم‌ترین سازندهای میزبان فسفات رسوبی در ایران است. نتایج آنالیز پراش اشعه ایکس (XRD) و مطالعات میکروسکوپ نوری و الکترونی بر روی نمونه‌های فسفات کانسار دلیر نشان داد که آپاتیت، کلسیت، کوارتز و دولومیت کانی‌های اصلی و کانی‌های فرعی شامل مونتموریلونیت، پیریت و باریت در مقادیر فرعی به همراه مقادیر جزیی سیدریت، روتیل، ایلیت و گوتیت هستند. میزان 5O2P، U و REE در نمونه‌های موردمطالعه به ترتیب در محدوده 5 تا 1/16 درصد، 9/1 تا 5/5 و 9/45 تا 9/136 پی پی ام متغیر است. نمونه‌های موردمطالعه دارای بی­هنجاری منفی Ce است که نشان‌­دهنده وجود یک محیط فاقد اکسیژن در زمان نهشت فسفات دلیر می‌باشد. براساس فاکتورهای کنترل‌­کننده تمرکز اورانیم در فسفریت‌ها، افق فسفاته سازند سلطانیه به دلیل شرایط آب و هوای گرم تا نیمه‌گرم مرطوب و pH خنثی تا اسیدی آب دریا در زمان تشکیل فسفات، پتانسیل غنی‌شدگی‌ اورانیم را ندارد. در نهایت، با توجه به این­‌که نتایج آنالیز شیمیایی نمونه‌های فسفات کانسار دلیر غنی‌شدگی‌ اورانیم نشان نمی‌دهد و هم‌­چنین با در نظر گرفتن فاکتورهای کنترل­‌کننده تمرکز اورانیم در فسفریت‌ها می‌توان پیش­‌بینی کرد احتمالاً سایر ذخایر فسفات سازند سلطانیه فاقد غنی‌شدگی‌ اورانیم هستند.

Palaeobiogeography, palaeoecology, and sequence stratigraphy of the Upper Jurassic carbonate succession of the Lar Formation, central Alborz Zone, Iran

Foraminifera, ammonites, and calcareous dinoflagellates were used for stratigraphy and, together with microfacies, for the assessment of the palaeoenvironmental conditions of the Upper Jurassic deposits in the central Alborz Zone of northern Iran. The Lar Formation (Lar Fm.) in the Polur section is of latest Oxfordian to early Kimmeridgian age. The ammonite Subnebrodites planula and the calcareous dinoflagellate Colomisphaera nagyi have been introduced as new biomarkers of the lower Kimmeridgian in the central Neo-Tethys. The distribution of calcareous dinoflagellates reflects possible dispersal routes along a narrow seaway between the western Neo-Tethys and the Alborz Zone in the central Neo-Tethys. The Terebella-Crescentiella associations of the Lar Fm. represent a low-energy setting under dysoxic conditions in the Central Neo-Tethys Ocean. The benthic foraminiferal assemblages in this formation show a high dominance of infaunal taxa and r-selected strategists. This assemblage is reminiscent of eutrophic conditions and low oxygen levels in the lower part of the Lar Fm. Good preservation of the hexactinellid sponges in the upper part of the Lar Fm. also indicates an oxygen-minimum zone. Three third-order depositional sequences can be distinguished in the study area based on six microfacies. Depositional sequence 1 (DS1) is composed mainly of argillaceous limestone and medium- to thick-bedded limestone, corresponding to an outer ramp-to-middle ramp environment. Depositional sequence 2 (DS2) comprises breccia limestone and thick-bedded limestone facies in its lower part and thin-bedded limestone to massive limestone in its upper part. The breccia limestone facies may be associated with subaerial exposure and reworking of previously deposited sediment during a relative sea level fall. The thin-bedded limestone to massive limestone of DS2 consists mainly of bioclastic mudstone to wackestone (outer ramp). These represent an deep-water outer homoclinal ramp facies. Depositional sequence 3 (DS3) consists mainly of massive limestone to thick-bedded limestone with a bioclastic peloidal microbial Crescentiella packstone (middle ramp). The relative stratigraphic positions of DSs1–3 and sequence boundaries in the uppermost Oxfordian to lower Kimmeridgian of the Polur area show a fair match to the upper Oxfordian to lower Kimmeridgian sequences (JOx7, JOx8, JKi1 and JKi2) on the global sea level curve.

Regional modeling and forecasting of precipitable water vapor using least square support vector regression

We propose a new model for spatio-temporal modeling and forecasting of precipitable water vapor (PWV) using least square support vector regression (LS-SVR) method. The LS-SVR uses simple linear equations. As a result, the complexity of the computational algorithm is reduced. In addition, the convergence speed and accuracy of the results increase. The evaluation of the new method has been done with the observations of the GPS networks at north-west and central Alborz in Iran. In the north-west GPS network, observations of 23 GPS stations in the period of 27 October to 10 November 2011 are used. However, in central Alborz network, the observations of 11 GPS stations in the period of 10 to 24 June 2016 have been used. The north-west GPS network is in the mountainous region and its observations are for the winter season. But, the second network is near the coastal area and summer season measurements are used. The latitude, longitude and height of GPS stations, DOY, time, relative humidity, temperature and pressure are considered as an input of the LS-SVR model. The output of the new model is the PWV (LS-SVRPWV). After the training step, the new model is used to estimate the spatio-temporal variation of PWV. The results of the LS-SVR model are compared and evaluated with the standard neural network (SNN), adaptive neuro-fuzzy inference system (ANFIS), support vector regression (SVR), Saastamoinen, global pressure and temperature 3 (GPT3), voxel-based tomography (VBT) models, as well as with radiosonde measurements. Error evaluation of models has been done in control stations as well as by precise point positioning (PPP) method. For LS-SVR model, the averaged RMSE in the control stations of the north-west GPS network is 1.69 mm, while for the central Alborz GPS network, 1.88 mm is calculated. Also, the averaged relative error of LS-SVR model calculated in the Tabriz and Tehran radiosonde stations are 4.66 % and 6.12 %, respectively. The results of this paper show that the LS-SVR model has a very high capability in forecasting the spatio-temporal variation of PWV at the GPS network territory. The new model can be used for accurate estimation of PWV, meteorological applications and flood forecasting.

Mineral lick use by a community of large herbivores in northern Iran.

Natural mineral licks are ecologically valuable resources to meet the physiological needs of herbivores, particularly in temperate forests. Importantly, licking sites can harbor high anthropogenic risk for conservation-dependent herbivores through higher chance of pathogen spillover from livestock and increased levels of poaching risks. However, to the best of our knowledge, there is no information on the mineral lick use in temperate forests of west Asia and the Caucasus where a few threatened deer species exist. We monitored four naturally occurring mineral licks in Central Alborz Protected Area, northern Iran during May-July 2019 using camera traps and analyzed the mineral content of the licking sites. A total of 53 independent mineral lick visits were obtained from only three species of herbivores, i.e., Caspian red deer (Cervus elaphus maral; n= 21), roe deer (Capreolus capreolus; n= 26), and wild pig (Sus scrofa; n= 6). The sex ratio of visiting Caspian red deer was highly skewed toward females (3M:18F), whereas it was more balanced in visiting roe deer (11M:15F). The species-level distribution of visits corresponded to diurnal and cathemeral for Caspian red deer and for roe deer, respectively, without any evidence of different activity curves. There was a negative nonlinear relationship between the ambient temperature and the visitation rate. Our findings showed that mineral licks are important habitat features for these large herbivores and need to be included in spatial mapping and habitat protection measures.

The role of active geological structures in forming hot springs in Ramsar, Iran

The hot springs of Ramsar, Iran are located at the northern zone of the Central Alborz Mountain Range along the Caspian Fault. Ramsar is a well‐known area with amongst the world's highest levels of natural radiation. Due to the local geology, which includes high levels of radium in rocks, soils, and groundwater, Ramsar residents are also exposed to high levels of alpha activity in the form of ingested radium. Nine springs were selected from the hot springs of Ramsar for this research, and water samples were tested to find the amount of dissolved materials and elements. Analysis of the results suggests that the hot springs of Ramsar originated from the sea. The results indicate that coincident with subduction of the southern Caspian basin and obduction of the Central Iranian crust over the southern Caspian crust, saline seawater reaches fracture zones of the Caspian Fault where it is heated due to mixing with radioactive materials and release of radon as a result of activity of the faults and its decay into radium. Then it migrates along the Caspian thrust faults and forms hot springs originated from regional surface waters of Ramsar. Those hot springs located next to thrust faults were the result of collision, and the origin of neighbouring cold springs is karst.

Mineralogy and geochemistry of Permian–Triassic lateritic‐bauxitic horizons, eastern and central Alborz, Iran: Implications for provenance, palaeogeography, and palaeoclimate

This paper presents a survey of geological attributes on the lateritic‐bauxitic deposits to examine their provenance, palaeogeography, and palaeoclimate condition in the Permian–Triassic boundary of Alborz Mountain, north Iran. The mineralogical analysis revealed that haematite, quartz, goethite, kaolinite, diaspore, boehmite, and anatase are the major rock‐forming minerals in these deposits. The major oxide composition of samples detected that enrichment of Al2O3 (up to 31.5%) and Fe2O3 (up to 37.9%) led to the formation of laterite, kaolinitic laterite, and bauxitic kaolinite. The distribution of trace and rare elements provides information about the enrichment of deposits concerning immobile elements. Employing geochemical proxies such as Al2O3/TiO2, bivariate diagrams of Eu/Eu* versus Sm/Nd and TiO2/Al2O3, enrichment of samples relative to heavy rare earth elements, and positive Eu anomaly revealed that the deposits originated from intermediate to mafic rocks. Several factors are inferred to be responsible for the transformation of parent rock(s) into lateritic‐bauxitic deposits: The high values of CIA, CIW, and PIA (mostly above 80) and increase of kaolinite point to deep to moderate parent rock(s) weathering, which is consistent with warming and humidity around the Permian–Triassic boundary. In continuation, transportation and trapping of weathered materials above the karstified carbonate bedrock of the Ruteh Formation and environmental interactions induced the formation of new minerals in a transitional environment near the vadose zone. The deposits have a generic correspondence with Palaeotethys Oceanic crustal subduction due to tectonic uplift, exhumation of bedrock, and regional sea‐level fall at the end of Palaeozoic that offered an opportunity for lateritization process.

Fluid inclusions and C–H–O–S–Pb isotope systematics of the Senj Mo–Cu deposit, Alborz magmatic belt, northern Iran: implications for fluid evolution and regional mineralization

AbstractThe Middle Eocene Senj Mo–Cu deposit (1.3 Mt at 1.5 wt % Cu and 0.2 wt % Mo) is located in the central Alborz magmatic belt, northern Iran. Mineralization is characterized by multistage veins, which are hosted in volcanic and volcano-sedimentary strata of the Karaj Formation (c. 41–45 Ma), genetically associated with the Senj Mafic Sill (c. 40 Ma). Four generations of veins are documented based on mineral assemblages and cross-cutting relationships, sequentially: quartz–biotite–chalcopyrite (QBC veins), quartz–molybdenum (QM veins), quartz–pyrite (QP veins) and late calcite (LC veins). Three types of fluid inclusions (FIs) are present in multistage veins: liquid-rich two-phase (L-type), vapour-rich two-phase (V-type) and solid-bearing multi-phase (S-type) inclusions. FIs in the QBC and QM veins are predominantly V-type and S-type, together with minor L-type, whereas the QP and LC vein minerals only contain L-type fluid inclusions. The homogenization temperatures of FIs from QBC to LC veins vary from 320 to 425 °C, 308 to 390 °C, 214 to 288 °C and 145 to 243 °C, and their salinities range from 5.3 to 49.0, 6.2 to 39.7, 5.7 to 13.0, and 2.1 to 7.2 wt % NaCl equiv., respectively. The H–O–C isotope compositions favour a dominantly magmatic origin for the hydrothermal fluids, which were gradually diluted by meteoric waters. The S–Pb isotope data of sulphide minerals indicate that the sulphur and metals were sourced from a deep-seated magmatic reservoir. The Senj Mafic Sill and associated Mo–Cu mineralization was developed in a back-arc extension regime, which faults and crustal fracture systems served as conduits for hydrothermal fluid circulation and Mo-rich veining.