NE Iran Research Articles

Possibility of Monte Carlo simulation for predicting radioactivity in the Baghak, NE Iran

Possibility of Monte Carlo simulation for predicting radioactivity in the Baghak, NE Iran

Mineral, bulk rock, and isotope geochemistry of the Late Cretaceous Sabzevar ophiolite in NE Iran and the magmatic and tectonic evolution of a continental back-arc basin oceanic crust in the Mesozoic Tethyan orogenic belt

Mineral, bulk rock, and isotope geochemistry of the Late Cretaceous Sabzevar ophiolite in NE Iran and the magmatic and tectonic evolution of a continental back-arc basin oceanic crust in the Mesozoic Tethyan orogenic belt

Upper Paleozoic komatiites near Mashhad, NE Iran

Upper Paleozoic komatiites near Mashhad, NE Iran

Multi-Sensor Satellite Remote-Sensing Data for Exploring Carbonate-Hosted Pb-Zn Mineralization: Akhlamad Area, Razavi Khorasan, North East Iran

The exploration of Pb-Zn mineralization in carbonate complexes during field campaign is a challenging process that consumes high expenses and time to discover high prospective zones for a detailed exploration stage. In this study, multi-sensor remote-sensing imagery from Landsat-8, Sentinel-2, and ASTER were utilized for Pb-Zn mineralization prospectivity mapping in the Akhlamad carbonate complex area, Razavi Khorasan, NE Iran. Due to the presence of carbonate formations and various evidence of Pb-Zn mineralization, this area was selected. Band composition, band ratio, principal component analysis (PCA), and SAM techniques for mapping alteration minerals as well as lineament analysis were implemented. Subsequently, a fuzzy logic model for identifying the prospective zones of Pb-Zn mineralization using multi-sensor remote-sensing satellite images was designed. The weight of each exploratory layer was determined using the fuzzy hierarchical method and the integration process of the information layers was performed using fuzzy operators. Finally, the existing mineral indications were used to evaluate and validate the obtained mineral potential map. The outcome of this investigation suggested several high-potential zones for Pb-Zn exploration in the study area.

Distribution and geographical differentiation of the Central Asian endemic species Lyela myops (Staudinger, 1881) (Lepidoptera, Nymphalidae, Satyrinae)

The article describes a new subspecies, Lyela myops tashkumirica ssp. nov. (Lepidoptera, Nymphalidae, Satyrinae) from Tashkumir vic., Jalal-Abad Region, Kyrgyzstan. The differences between the new taxon and the previously described L. myops myops (Staudinger, 1881) (E Kazakhstan and N Kyrgyzstan), L. myops mangystavica Lukhtanov, 1994 (W Kazakhstan), L. myops babatagi Tshikolovets, [1998] (S Uzbekistan and E Turkmenistan) and L. myops tekkensis (Staudinger, 1886) (NE Iran and SW Turkmenistan) are described in detail.

Rare bioerosion in large benthic foraminifera in the Eocene of NE Iran: Implications for global warming and trophic regime

Bioerosion is rare in large benthic foraminifera (LBF) in the Eocene of Ziarat Formation, Iran. Three bioerosion ichnotaxa have been identified, including more common Trypanites isp. and Entobia isp., and rare Meandropolydora sulcans. The rare bioerosional traces in LBF tests support the scenario of an oligotrophic nutrient regime during the studied interval. The sedimentation rate may have also been among the controls on the bioerosion of LBF in the Middle Eocene of Iran, but the oligotrophic nutrient regime likely had a stronger effect. The bioerosion of LBF tests during the Middle Eocene Climatic Optimum (MECO) was rather low or at maximum moderate, suggesting that an oligotrophic nutrient regime could compensate for the increase in bioerosion caused by ocean acidification and warming.

Biostratigraphy and facies around the D/C boundary interval of the Tuye-Darvar section, Eastern Alborz Range, NE Iran

The 1st order mass extinction at the Devonian/Carboniferous transition, known as the Hangenberg Crisis, is characterized by major transgressive/regressive cycles which led to widespread ocean anoxia during the Hangenberg Black Shale Event, as well as to a global major sea-level fall and the worldwide deposition of regressive Hangenberg Sandstone equivalents. The Devonian/Carboniferous transition at the Tuye-Darvar section in the eastern Alborz Range is studied in terms of conodont biostratigraphy, litho-, microfacies and sequence stratigraphy. In order to examine the biostratigraphical framework, forty conodont samples were systematically taken from the studied interval. Thirty-two conodont species belonging to ten genera led to the discrimination of twelve conodont zones, ranging from the Pseudopolygnathus granulosus Zone to the Scaliognathus anchoralis-Doliognathus latus Zone. Due to facies, the conodont record also exhibits some hiatuses. Field observations and sedimentological and microfacies studies led to the identification of thirteen facies types from sub-tidal environments to the fully marine environments, including seven microfacies types. The sediments deposited in a mixed carbonate-siliciclastic platform, revealed four third-order sequences. The Hangenberg Black Shale is not recorded in the Tuye-Darvar section as a result of depositional facies. In comparison with other studied Devonian/Carboniferous Boundary (DCB) sections of the central and northern Iran, the Tuye-Davar section suggests a tectonic position, which is most likely placed on a separate tectonic block.

Comments on “Morphogenesis of Balkhania balkhanica Mamontova, 1966 (benthic foraminifera) from Lower Cretaceous successions along the northern Tethyan margin (NE and Central Iran)”

The study by Gheiasvand and Bartolini (2023) treated Balkhania balkhanica and Torinosuella peneropliformis as morphotypes of a single species, Balkhania balkhanica, leading to incorrect conclusions about its characteristics. Their analysis overlooked key aspects of the life cycle, morphotypes, ecological roles, and paleogeographical distribution of B. balkhanica due to a misunderstanding of foraminiferal systematics. Notably, its megalospheric forms can reach a maximal diameter of 5.2 mm, whereas its microspheric forms may reach up to 15 mm. Its stratigraphic range is limited to the Barremian-early Aptian interval. Although B. balkhanica and Choffatella decipiens share equivalent ecological niches, they are not found together in the same strata. Ch. decipiens has a much wider distribution, over most of the Tethys realm, whereas Balkhania balkhanica is primarily found in the northern Tethys platforms, with the notable exception of Lebanon in the southern Tethys platforms.

Correction to: ‘The Generation of Eocene Mafic dike Swarms During the Exhumation of a Core Complex, Biarjmand Area, NE Iran’ by Azizi et al. (2023), Journal of Petrology, 64, 1–118

Correction to: ‘The Generation of Eocene Mafic dike Swarms During the Exhumation of a Core Complex, Biarjmand Area, NE Iran’ by Azizi et al. (2023), Journal of Petrology, 64, 1–118

Geologically-constrained GANomaly network for mineral prospectivity mapping through frequency domain training data

Generative adversarial networks (GAN) and various deep autoencoders have been frequently executed to recognize multi-element geochemical anomalies linked to different ore resources in recent decade. Efficient recognition of multi-element geochemical anomaly patterns is a significant issue in mineral exploration targeting. Traditional procedures have not sufficient capability to perform efficient pattern recognition. While, deep learning algorithms as influential subset of machine learning algorithms can present magnificent conclusions in classification and pattern recognition. Because those have robust ability in extracting high-level features of complex inputs. Although, many deep learning algorithms were used to recognize geochemical anomalies but the GANs have demonstrated specific dignity in recognizing multi-element geochemical anomaly patterns. But, these frameworks should be constrained to learn geological knowledge and yield reasonable potential maps. In this regard, a novel geologically-constrained GANomaly was trained with frequency domain training data to recognize multi-element geochemical anomalies. Application of the geologically-constrained GANomaly network with considering mineral system parameters of the Au–Cu mineralization in the Feyzabad district, NE Iran was eventuated to suitable results. The success-rate curves demonstrated that produced map of frequency domain geochemical data has traced 86.68% Au–Cu occurrences via 30% corresponded area while produced map of spatial domain geochemical data has traced 80.13% Au–Cu occurrences via 30% corresponded area.

Relative contributions of taxonomic and functional diversity to the assembly of plant communities hosting endemic Dianthus species in a mountain steppe

Plant community assembly is the outcome of long-term evolutionary events (evident as taxonomic diversity; TD) and immediate adaptive fitness (functional diversity; FD); a balance expected to shift in favour of FD in ‘harsh’ habitats under intense selection pressures. We compared TD and FD responses along climatic and edaphic gradients for communities of two species (Dianthus pseudocrinitus and D. polylepis) endemic to the montane steppes of the Khorassan-Kopet Dagh floristic province, NE Iran. 75 plots at 15 sites were used to relate TD and FD to environmental gradients. In general, greater TD was associated with variation in soil factors (potassium, lime, organic matter contents), whereas FD was constrained by aridity (drought adaptation). Crucially, even plant communities hosting different subspecies of D. polylepis responded differently to aridity: D. polylepis subsp. binaludensis communities included a variety of broadly stress-tolerant taxa with no clear environmental response, but TD of D. polylepis subsp. polylepis communities was directly related to precipitation, with consistently low FD reflecting a few highly specialized stress-tolerators. Integrating taxonomic and functional diversity metrics is essential to understand the communities hosting even extremely closely related taxa, which respond idiosyncratically to climate and soil gradients.

Biostratigraphy and determination of the base of the Santonian stage in the east of the Kopeh-Dagh Basin based on planktonic foraminifera, NE Iran

The Abderaz Formation has been studied in five stratigraphical sections (Qarehso, Abderaz village, Muzduran pass (type section of the formation), Padeha village, and Shorab) in the east of the Kopeh-Dagh Basin. Twenty-four species of planktonic foraminifera belonging to eleven genera were identified. The vertical distribution of these species helped to recognize five biozones within the Abderaz Formation as follows: 1) Whiteinella archaeocretacea Partial Range Zone, 2) Helvetoglobotruncana helvetica Total Range Zone, 3) Marginotruncana schneegansi Partial Range Zone, 4) Dicarinella concavata Interval Zone, 5) Dicarinella asymetrica Total Range Zone. Based on these data, the Abderaz Formation ranges from the latest Cenomanian to late Santonian. The base of the Santonian stage was placed close to the onset of the Dicarinella asymetrica Total Range Zone at the studied sections. It was precisely traced at the FO of Globotruncana linneiana (pillbox-like).

Lithium exploration targeting through robust variable selection and deep anomaly detection: An integrated application of sparse principal component analysis and stacked autoencoders

Lithium is a strategic metal for high-technology industries that plays a vital role in realizing electromobility and effective energy storage for smartphones and electric/hybrid vehicles, in addition to being important in accumulating energy from renewable sources. Motivated by this, the development of state-of-the-art workflows is imperative to make Li exploration more efficient and guarantee a sustainable supply to the demanding markets in the future. In this paper, a computational protocol was described to address two critical challenges raised in the Li exploration: (i) selection of mineralization-related pathfinder variables and (ii) recognition of multi-element geochemical anomalies related to ore-forming processes. Robust sparse principal component analysis (SPCA) was employed to reduce active (non-zero) loading coefficients and straightforward selection of Li pathfinder variables. The selected variables were then fed into the training network of stacked autoencoders (SAE) to learn deep representations of multivariate input signals and quantify reconstruction errors linked to Li-vectoring geochemical anomalies. As a representative example, the proposed workflow, i.e., SPCA + SAE, was implemented in the R programming language and applied to a real-case experiment with stream sediment geochemical data pertaining to the Moalleman district, NE Iran. Moreover, compositional robust principal component analysis (RPCA) and Mahalanobis distance (MD) technique were adopted to constitute two comparative models, RPCA + SAE and SPCA + MD, as benchmarks to judge the competence of the SPCA + SAE model in variable selection and anomaly detection, respectively. A performance appraisal by success-rate curves and relevant area under the curves (AUCs) indicated that the SPCA + SAE model brings, by calculating the highest AUC, spatial patterns that are more promising for vectoring towards Li-mineralized grounds. Moreover, AUCSPCA+MD was measured to be greater than AUCRPCA+SAE, suggesting robust variable selection is a more important paradigm than deep anomaly detection for Li exploration targeting. Student's t–statistic method was eventually applied to the anomaly map from the SPCA + SAE model to define relevant thresholds for narrowing down prospective areas for the next round of Li exploration within the study area.

Epilithic diatoms distribution in four tributaries of the Gorganrud River (NE Iran)

Epilithic diatoms distribution in four tributaries of the Gorganrud River (NE Iran)

Comment on ‘The Generation of Eocene Mafic Dike Swarms During the Exhumation of a Core Complex, Biarjmand Area, NE Iran’ by Azizi et al. (2023), Journal of Petrology, 64, 1–18

Abstract Azizi, H., Daneshvar, N., Asahara, Y., Minami, M. & Anma, R. (2023). The generation of Eocene mafic dike swarms during the exhumation of a Core complex, Biarjmand area, NE Iran. Journal of Petrology64, 1–18 have attributed the E–W-oriented mafic dike swarm in the Biarjmand metamorphic core complex to an Eocene extensional event which is much younger than a previously suggested Late Jurassic–Early Cretaceous age. They proposed that the emplacement of these dikes occurred in a rapid extensional regime coeval with the exhumation of the core complex after gravitational instability in the Central Iran/Eurasia collision zone. I appreciate the opportunity this article provides to shed light on specific aspects of the Late Mesozoic–Early Cenozoic continental extension within the Eurasian sector of the Neotethys subduction system. However, I here bring to attention certain discrepancies within Azizi et al.'s publication. Specifically, the assignment of an Eocene age to the emplacement of the E–W-oriented dike swarm, even though purportedly supported by U–Pb zircon dating, appears to be at odds with field observations and previously published geochronological data. Furthermore, the article contains internal contradictions in its presentation of the core complex model for the study area. It is important to note that Malekpour-Alamdari, A., Axen, G. J., Heizler, M. T. & Hassanzadeh, J. (2017). Large-magnitude continental extension in the northeastern Iranian plateau: insight from K-feldspar 40Ar/39Ar thermochronology from the Shotor Kuh-Biarjmand metamorphic core complex. Geosphere13, 1207–1233 previously documented the geochronological-based metamorphic core complex model of the area. Regrettably, despite its direct relevance, these earlier works have not been acknowledged in Azizi et al.'s paper. In this comment, I outline the problems with the structural and regional geology, the zircon U–Pb age of the dike samples, the age of the dike swarm, and the geodynamic interpretations in Azizi et al.'s work.

Spatial relationship of landform surface features and biocrusts, and their effect on soil microbial biomass on an alluvial fan

AbstractThe spatial cover of biocrusts represents a suitable habitat for the activity of soil microorganisms in semi‐arid and arid regions. Microorganisms are one of the essential components of soil quality. Therefore, it is necessary to understand the processes of biocrust habitat formation in landforms and their mutual relationship with soil properties. We studied the spatial distribution of biocrusts and their effect on soil microbial biomass and carbon activity in a semi‐arid alluvial fan in NE Iran. A total of 72 soil samples (using plots 0.25 m2) from the topsoil layers (0–5 cm) were collected along the alluvial fan in September 2020. Soil surface properties and microbial biomass in two categories of biocrust and non‐biocrust were investigated in three classes of biocrusts coverage obtained by geostatistics. Our results revealed that biocrusts had a negative correlation with gravel coverage and elevation; in contrast, the suitable spaces for biocrusts growth were created by cobble clasts. The biocrusts have provided favourable conditions for soil microorganisms by altering the properties of the soil (such as increasing organic carbon, nitrogen and available phosphorus and decreasing pH), and thus they increased basal soil respiration and microbial biomass. Different microbial activities were led by the predominant type of biocrusts, as the chlorolichen crusts had the most significant effect on increasing the microbial biomass phosphorus while cyanolichen crusts increased the microbial biomass carbon. Moss and cyanolichen crusts increased microbial activity and respiration more than cyanobacteria crusts. Therefore, the soil quality has improved by biocrusts in semi‐arid ecosystems.

Geochemistry and geochronology of the Neyshabur meta-volcanic rocks, Binalood mountains, NE Iran: witnesses of Paleo-Tethys rifting and closure

Geochemical and geochronologic data are presented for meta-mafic to meta-felsic rocks along the Paleo-Tethys Suture in the Binalood Mountains east of Neyshabur, NE Iran. The rocks have a late Cambrian age (U–Pb zircon, ~ 490 Ma) and were metamorphosed in the Early Jurassic (40Ar/39Ar amphibole and plagioclase, 199–192 Ma). The rocks of this suite are alkaline and sub-alkaline (tholeiitic). The alkaline rocks are enriched in light relative to heavy rare earth elements, and do not show depletion of high-field strength elements on primitive mantle-normalized multi-element diagrams; they are similar to ocean island basalts (OIB). The tholeiitic rocks are depleted in Nb and Ta and have higher MgO and lower TiO2 than the alkaline rocks. Both types have similar, high and variable 87Sr/86Sr(i) isotopic compositions of 0.7044 to 0.7082 and 143Nd/144Nd(i) values of 0.5118 to 0.5122. The alkaline rocks are lower-degree partial melts than the tholeiitic rocks and were generated at greater depths; they likely originated from a garnet pyroxenite-rich source. The spatial, temporal, and geochemical relationships of early Paleozoic meta-mafic to felsic rocks along the Paleo-Tethys Suture (e.g., Shahrud, Jajarm, Binalood, Torbat-e-Jam) substantiate the role of a mantle plume in continental breakup along the northern margin of Gondwana and a late Cambrian-Ordovician onset of rifting that resulted in the opening of the Paleo-Tethys Ocean. The Early Jurassic metamorphism post-dates its closure.Graphical abstract

Melting of Subducted Continental Crust in the Cimmerian Collisional Orogenic Belt, NE Iran

Abstract The subduction of continental crust in orogenic belts that are not associated with high-pressure metamorphism is still poorly understood. The Late Triassic postcollisional granitic rocks of NE Iran are related to the convergence between the Central Iran terrane and the Turan terrane on the southern margin of the Eurasian continent. They intruded into the Paleo-Tethyan suture between the Central Iran and Turan terranes. Granitoids of the Torbat-e-Jam pluton were emplaced at ca. 217 Ma, and their moderately high SiO2 (>64 wt. %), low MgO contents (mostly <2 wt. %), slightly depleted Sr-Nd, and zircon Hf isotopes suggest partial melting of a juvenile crust. Granodiorites from NW and SE Mashhad were emplaced at ca. 217 and 200 Ma, and their geochemical features and enriched Sr-Nd and zircon Hf isotopes suggest melting of continental crust. Inherited zircon cores in both the NW and SE Mashhad intrusions have dominant age peaks of ca. 540 and 770 Ma, similar to the age spectrum of adjacent Paleozoic sediments derived from the Central Iran terrane, but distinct from Triassic sediments sourced from the Turan terrane. The inherited zircon cores cannot be explained by crustal contamination during magma ascent, rather the age pattern of inherited zircon cores coincides with major magmatic events in the Central Iran terrane and fingerprint their source, suggesting partial melting of the subducted Central Iran continental crust. This study suggests that the melting of subducted continental crust can occur in simple collisional belts, rather than being confined to ultrahigh-pressure metamorphic orogenic belts.

Arc magmatism associated with continental convergence in the SE segment of the UDMA, Iran: Insights from zircon geochronology and Hf–Sr–Nd–Fe isotopes

Magmatic suites provide the keys to evaluate the growth and reworking of continental crust. Late Cretaceous to Pleistocene convergence in the Urumieh–Dokhtar magmatic arc (UDMA) of Iran produced continental-arc magmatism that traces the transition from subduction to collision. The extent and origin of some magmatic segments in the SE UDMA remain poorly understood. The Oligocene (31 to 25 Ma) Jiroft plutonic rocks here investigated encompass the compositional spectrum from gabbro to granodiorite. Zircon εHf(t) (−1.3 to +8.1), whole rock εNd(t) (+0.8 to +3) and δ56Fe (0.07‰ to 0.16‰) are intermediate between values of depleted mantle and arc-related magmas, and indicate low degrees of oxidization of metasomatized mantle. Modelling indicates that the trace element patterns of Jiroft parental melts can be closely replicated by 4% partial melting (i.e., F = 4%) of a mantle source which was metasomatized by 2% of sediment melt. The parental melt fits well with a model pattern of ∼97% batch melt (i.e., 98% DM + 2% sediment at F = 4%) and contaminated with ∼3% upper crustal components. The 31–25 Ma magmas of the SE UDMA formed before the main collision event (< 20 Ma) between Arabia and Iran, in conjunction with changing tectonic regime from extensional to compressional. Compilation of the Cenozoic magmatic front (i.e., UDMA) and rear-arc (NE Iran and Alborz–Azerbaijan) data reveals variable degrees of crustal cannibalization during the flare-up episodes. We find that individual segments of the UDMA experienced different geodynamics conditions, further documenting the diachronous collision and correspondingly non-uniform crustal thickening across the UDMA.

Estimation of porosity and volume of shale using artificial intelligence, case study of Kashafrud Gas Reservoir, NE Iran

The key problem in oil exploration and engineering is the lack of accurate and reliable data about the reservoir parameters of a field. Having a precise assessment of petrophysical properties can provide the ability to make decisions with a high degree of confidence about planning for production, exploitation, and further field development scenario. In this research, an artificial intelligence (AI)-based approach was developed to improve the estimation of reservoir parameters including porosity and volume of shale, which has a significant role in different stages of hydrocarbon exploration, in the Kashafrud Gas Reservoir in the northeast of Iran. For this purpose, we measured the petrophysical properties of 27 samples of the Kashafrud Formation. To increase the amount of data for employing a multilayer perceptron (MLP) artificial neural network (ANN), a geostatistical algorithm was used to increase the amount of laboratory measured data of porosity and volume of shale to 686 and 702, respectively. In addition, 2263 well-logging data from the same well were provided. The optimal MLP network with the topology of 6-7-1, and 6-8-1 was selected to estimate the porosity and shale volume with mean squared error (MSE) of 2.78731E−4, and 1.28701E−9, respectively. The training process was performed using two different sets of input data. In the first approach, all available well-logging data were used as input, ending up in high MSE. In the second approach, some selected well logs were used based on the results of sensitivity analysis which clearly improved the estimations. The ability of MLP networks made great improvements in the estimation of the both parameters up to 99.9%. The presence of valuable core data in this study significantly improved the process of comparison and conclusion. The final results prove that AI is a trusted method, also the potential of the ANN method for the reservoir characterization and evaluation associated problems should be taken into consideration. Due to the unavailability of core data along the whole wells, the application of intelligent methods, such as machine learning (ML) can be used to estimate the parameters in other oil or gas fields and wells.