North-central Iran Research Articles

Quantifying the features of earthquake clusters in north-Central Iran, based on nearest-neighbor distances and network analysis

The statistical features of earthquake clusters in North-Central Iran (Tehran Region) are investigated, with the aim of quantitatively characterizing the properties of earthquake triggering and allow exploring their possible relations with the tectonic setting of the study area.The nearest-neighbor approach is used for the identification of the earthquake clusters in the space-time-energy domain. This approach permits for a data-driven identification of clusters so that, within multi-event clusters, the features of secondary and higher orders dependent events can be explored. The study is based on a revised dataset that is extracted from the catalog compiled by the Iranian Seismological Center (IRSC) for the period of 1996–2022. In order to exclude the effect of non-tectonic events, which turn out quite numerous within the study region, explosions within quarry-rich areas are removed; the identification of non-tectonic events is performed by considering the normalized ratios of daytime to nighttime events in an iterative removal procedure. According to preliminary analysis of the resulting catalog, an area is selected, within which a satisfactory completeness level is assessed for events with magnitude >2.0. Robust values of the scaling parameters, namely the b-value and the fractal dimension of epicenters, are also computed and are used to calculate the nearest-neighbor distances and to identify the earthquake clusters.The nearest-neighbor method also permits to investigate the internal structure of earthquake sequences, and to differentiate the spatial properties of seismicity according to the different topological features of the clusters structure. The obtained results allow us identifying two macro-areas, approximately separated by the 52°E meridian, which are characterized by different clustering features, namely: high complexity indexes, indicating simple (burst-like) structure of clusters, to the East; low complexity index, corresponding to complex multi-level (swarm-like) structure of clusters, to the West. The complexity measures, borrowed from network theory (i.e. the Closeness and Outdegree Centralization indexes), consistently capture the complexity of the identified clusters, and confirm that the cluster structures have distinct preferred geographic locations. The territorial heterogeneity of the examined clustering properties can be related with the spatial variability of tectonic, structural and geophysical features of the Alborz region, in good agreement with findings from the Alps-Dinarides junction (Northeastern Italy), a region also characterized by a contractional structural setting, mainly including reverse and strike-slip faulting systems, and by moderate to high seismic activity.

Eocene mafic alkaline volcanism in north Central Iran; Signatures of development and subsequent melting of a pyroxenite mantle source

Volcanic rocks from the Miami-Davarzan area are basalts to trachyandesites interlayered with fossiliferous beds and bear significant implications on the Eocene geodynamic evolution of northern central Iran. The rocks constitute two distinct groups, a low-Nb and a high-Nb suite. The least evolved low-Nb suite includes clinopyroxene-olivine phyric samples and is characterized by higher CaO and lower Al2O3 as compared to peridotite partial melts. The high-Nb suite includes more evolved plagioclase-clinopyroxene phyric samples. Fractional crystallization modeling using least-squares mass balance calculations for major elements suggests that the high-Nb suite was formed from a low-Nb parental melt by differentiation of a clinopyroxene-dominated mineral assemblage. The Miami-Davarzan volcanic rocks are characterized by significant large ion lithophile elements (LILE) and light rare earth elements (LREE) enrichment and high field strength elements (HFSE) depletion, which are typical signatures of subduction-related settings. Immobile, highly to moderately incompatible elements such as NbTa, LaCe, PrNd are higher in the Miami-Davarzan volcanic rocks as compared to the typical magmatic arcs, which is an indication of slab melt involvement and metasomatism of the mantle source. The Sr-Nd-Pb isotopic data also confirm a common mantle source involving the addition of subducted sediments into a depleted mantle source for both the low-Nb and high-Nb suites. The geochemical characteristics such as high CaO, low Al2O3, and the isotopic data can be best explained by derivation of the low-Nb suite parental melt from a pyroxenite mantle source. The pyroxenite mantle source was probably developed as a result of interaction between shallow depleted mantle and slab plus sediment-derived melts. It is suggested that the extensional phase that dominated the northern central Iran during the Eocene prompted partial melting of a pyroxenite mantle source.

Reactivation of an old landslide in north–central Iran following reservoir impoundment: Results from multisensor satellite time-series analysis

Water impoundment combined with more frequent precipitation extremes due to climate change increases landslide hazards on the slopes surrounding dam reservoirs. In situ monitoring systems in these potential landslide-prone areas are often unavailable, making landslide failures challenging to forecast. This paper describes a multisensor and multivariate remote sensing approach using data from Envisat, Sentinel-1, Landsat and PlanetScope satellites to reconstruct the spatiotemporal evolution of the mechanism and causes of the March 2019 landslide failure backside of the dam reservoir in Hoseynabad-e Kalpush village, north–central Iran. Statistical analysis and time series clustering are performed to derive the main landslide kinematic features from multitemporal interferometric synthetic aperture radar (MT-InSAR) analysis. We also exploit GIS and wavelet analysis to correlate potential external driving factors with landslide kinematics. Envisat and Sentinel-1 MT-InSAR analyses revealed that a previously stable old landslide was reactivated following reservoir impoundment in early 2013. As the reservoir water level rose during the following years up to 34 m in 2019, the landslide displacement rate gradually increased from 3.5 cm/yr to 8.4 cm/yr, and the destabilization gradually propagated upslope. At this stage, seasonal precipitation effects were detected only in the vertical component, indicating swelling and shrinkage movements of the shallower soil layer. The reactivated landslide accelerated and catastrophically failed following the exceptional precipitation in early 2019, producing a horizontal shift of >40 m, detected with optical image digital correlation. In the aftermath, the landslide continued to move with a decreasing trend until final stabilization in October 2021. Our study demonstrates how combined observations derived from multisensor satellite remote sensing data can be used to assess landslide precursors and kinematics, as well as the influence of climatic and anthropogenic factors on the instability of slopes surrounding water reservoirs. This is especially relevant in data-scarce areas.

On the occurrence of Neoplanorbulinella Matsumaru, 1976 (Foraminifera) from the late Oligocene of Central Iran (Qom Formation): Palaeobiogeographic implications

The shallow marine carbonates of the upper Oligocene Qom Formation yielded several occurrences of the foraminiferan genus Neoplanorbulinella Matsumaru. Neoplanorbulinella saipanensis Matsumaru has so far been recorded from the late Eocene–early Miocene of Japan and late Oligocene of NE Italy whereas N. malatyaensis Gedik is only reported from the Oligocene from its type locality in the Malatya Basin, eastern Turkey. The new records reported here from the Qom Formation indicate that both species occur in the Dobaradar section, ca. 10 km south of the city of Qom in North–Central Iran. The palaeogeographic distribution of these two species therefore has to be extended as far as the palaeolongitude of current Central Iran. The accompanying larger benthic foraminifers, including Miogypsinoides complanatus (Schlumberger), M. formosensis Yabe and Hanzawa, Spiroclypeus margaritatus (Schlumberger), Operculina complanata (Defrance), and Risananeiza pustulosa Boukhary et al., indicate the upper Chattian SBZ 23 Zone. The co-existence of the N. saipanensis and N. malatyaensis points to suitable palaeobiogeographic conditions of Central Iran to host Western and Eastern Tethyan taxa.

Molecular Identification of Cutaneous Leishmaniasis Species in the Northcentral Iranian Province of Alborz: Is There a New Focus on Cutaneous Leishmaniasis in the Province?

Cutaneous leishmaniasis (CL) is an endemic infection in the Middle East, including Iran that is also spreading to new foci. We aimed to determine the leishmaniasis species causing CL in Alborz province. Overall, out of 55-suspected CL patients referred to health centers in Alborz Province, north central Iran in 2019, 40 patients had positive smear for CL based on optical microscopy. The internal transcribed spacer 1 (ITS1) of nuclear ribosomal DNA (rDNA) was amplified by PCR. Leishmania species were identified by PCR-restriction fragment length polymorphism (PCR-RFLP) using BshF I (Hae III) enzyme. Out of the 40 positive patients with CL, 34 cases (85%) had been caused by Leishmania (L) major and six (15%) by L. tropica. Fifteen patients had no history of traveling to the disease endemic areas, of which nine were Iranians. Skin lesions and scars caused by CL were mostly observed on the hands and face. Moreover, more than two skin lesions were observed in 22 cases (55%), all of which were infected with L. major. A single skin ulcer was seen in 18 (45%) of the CL patients. Climate change, reduced rainfall, and demographic changes such as migration into Alborz Province and the increasing marginalization of the population and their entry to settle in new areas might have caused natural transmission of both L. tropica and L. major in this province.

Optimal redesign of coastal groundwater quality monitoring networks under uncertainty: application of the theory of belief functions.

This paper presents a new methodology for the optimal redesign of water quality monitoring networks in coastal aquifers. The GALDIT index is used to evaluate the extent and magnitude of seawater intrusion (SWI) in coastal aquifers. The weights of the GALDIT parameters are optimized using the genetic algorithm (GA). A SEAWAT-based simulation model, a spatiotemporal Kriging interpolation technique, and an artificial neural network surrogate model are then implemented to simulate total dissolved solids (TDS) concentration in coastal aquifers. To obtain more precise estimations, an ensemble meta-model is developed using the Dempster-Shafer's belief function theory (D-ST) to combine the results obtained from the three individual simulation models. The combined meta-model is then used for calculating more precise TDS concentration. Some plausible scenarios are defined for variation of water elevation and water salinity at the coastline to incorporate uncertainty through the concept of value of information (VOI). Finally, the potential wells with the highest values of information are taken into consideration to redesign coastal groundwater quality monitoring network under uncertainty. The performance of the proposed methodology is evaluated by applying it to the Qom-Kahak aquifer, north-central Iran, which is threatened by SWI. At first, the individual and ensemble simulation models are developed and validated. Then, several scenarios are defined regarding the plausible changes in TDS concentration and water level at the coastline. In the next step, the scenarios, the GALDIT-GA vulnerability map, and the VOI concept are used for redesigning the existing monitoring network. The results illustrate that the revised groundwater quality monitoring network containing 10 new sampling locations outperforms the existing one based on the VOI criterion.

New evidence on cryptic speciation in soil-inhabiting nematodes, with morphological and molecular characterisation of Xiphinema sangesarense n. sp. (Dorylaimida: Longidoridae) from north-central mountains of Iran

Summary A new species of the dagger nematode, genus Xiphinema, was recovered from the rhizospheric soil samples collected from rangelands in Semnan province, north-central Iran, and described based upon both morphological and molecular data. Xiphinema sangesarense n. sp. is characterised by 3.7-4.8 mm long females having 136-154 μm long odontostyle, 74-87 μm long odontophore, two equally developed genital tracts with crystalloid bodies in the tubular part of the uterus, short dorsally convex, ventrally slightly convex tail with a mucron at the end, four juvenile developmental stages and males present, functional. The new species most closely resembles X. azarbaijanense and is regarded as its tentative cryptic form, but was separated from it by reproductive mode, and morphological and molecular differences. Compared to X. afratakhtehense, the second similar species, it could be separated based on morphological differences, especially characteristics of juveniles and molecular data. Furthermore, the new species has close morphology with five know species, namely: X. aequum, X. horvatovicae, X. illyricum, X. macedonicum and X. vuittenezi, in terms of morphological characteristics (mainly structure of uterus and similar female tail), and their differences are discussed. In phylogenetic analyses of the new species using several sequences of two partial large subunit (LSU) D2-D3, and internal transcribed spacer (ITS) sequences, the new species formed a clade with Xiphinema sp. in the LSU tree, and in the ITS tree it formed a clade with X. afratakhtehense. In the cytochrome c oxidase I (COI) gene tree, sequences of the new species occupied a placement inside the clade of several sequences of X. afratakhtehense.

Y-chromosomal Short Tandem Repeat Variation in Kurd, Assyrian, and Armenian populations in Iraq Kurdistan

Background: North central Middle Eastern countries Iran, Iraq, Turkey, and Syria all have persistent Kurdish regions. Over thousands of years, several ethnicities have immigrated, settled, or resided in the region, including Turks, Persians, Arabs, Kurds, Armenians, Assyrians, Chechens, and Azeris. Methods: Eleven Y-chromosome STRs were evaluated in a total of 90 unrelated males from the Kurds, Armenians, and Assyrians populations in the Kurdistan region of Iraq (DYS19, DYS390, DYS393, DYS426, DYS437, DYS439, DYS447, DYS460, DYS461, DYS481, and DYS576). Using a DNA extraction kit, total DNA was isolated from leukocytes. PCR products were run on 8% polyacrylamide gel with a 50bp ladder DNA marker to size the bands, and silver staining was used to identify the DNA bands. Power Marker V3.25 software was used to determine variety of genetic parameters, including total allele number, allele frequency, gene diversity, polymorphic information content (PIC), and phylogenetic tree was constructed by MEGA-X software. Results: The total number of alleles identified in the three populations was 380. The sizes of the alleles ranged from 87bp to 275bp.The most diverse loci were DYS447 and DYS576 (GD: 0.949), whereas DYS426 showed the least diversity (GD:0.896). The Phylogenetic tree divided the populations into two main clusters: The Kurdish and Armenian clades in one cluster and the Assyrian in another cluster. Few of dendrogram leaves from the three examined groups were admixed with each other. Conclusions: This study confirms the high-resolution Y-STR typing's ability to discriminate. We conclude that the genetic distance between Kurd and Armenians is less than the genetic distance between the Kurd and the Assyrians, meaning that the Armenians population are genetically closer to the Kurds population.

Time Series Model for Forecasting the Prevalence of Some Important Parasitic Infections in Slaughtered Sheep in North-Central Iran

Uncontrolled parasitic infections in livestock can increase the potential risk of transmission between human societies. Owing to the socioeconomic challenges of these diseases in slaughtered sheep, the current study aimed to forecast the prevalence of these infections in a central slaughterhouse in Alborz Province, north-central Iran. Data from 2009 to 2018 on parasitic infections in slaughtered sheep presented at a slaughterhouse were compiled and the prevalence of these diseases was computed. The prevalence has been considered as a time series and afterward, RStudio software using the best-fitted ARIMA model was applied to forecast the monthly variation in prevalence rates. From 2009 to 2018, a total of 1,339,196 sheep were slaughtered in the studied slaughterhouse. The Iranian Afshari breed was the most slaughtered sheep and, a total of 77.6% of these animals were raised under traditional farming system. In addition to the Alborz province, slaughtered sheep were brought from five other provinces, including Zanjan, Qazvin, Qom, Kurdistan, and East Azerbaijan. The highest and lowest total prevalence of studied parasitic zoonoses in slaughtered livestock were cystic echinococcosis (12.76%) and Taenia ovis infection (0.01%), respectively. An approximate stationary trend for fascioliasis and CE and a mild decreasing trend for dicrocoeliasis and sarcocystosis has been forecasted for the next 10 years. Forecasting the prevalence of T. ovis infection showed that without implementing control strategies, this infection would be increased in the years ahead. The current study has demonstrated for the first time the predicting of some important parasitic infections in sheep in Iran. The results provide helpful data for authorities for controlling these diseases in the frontline of meat production. Vast and in-depth forecasting investigations is required to find evidence-based data about these infections for entire the country of Iran.

Evaluation of climate change effects on flood frequency in arid and semi-arid basins

Abstract Climate change (CC) will increase the intensity of extreme phenomena such as drought and flood in arid and semi-arid regions. This will cause the water supply of these areas to become very difficult in times of crisis. This study identifies sub-basins with high flood potential in the baseline period (1982–2005) and the future period (2025–2048) in the Hablehroud basin, north-central Iran. It uses the soil and water assessment tool (SWAT) and 23 coupled model intercomparison project 5 (CMIP5) general circulation models (GCMs). It estimates the instantaneous peak flow (IPF) and uses a flood index (FI) to determine the contributions of each sub-basin to the floods. The rainfall of the basin will increase by 11.5% under representative concentration pathway (RCP) 4.5 and 12.6% under RCP 8.5. The minimum daily temperature (Tmin) of the basin will increase by 0.8 °C under RCP 4.5 and 1.1 °C under RCP 8.5 in the future period. In addition, the maximum daily temperature (Tmax) will rise by 1 °C under RCP 4.5 and 1.2 °C under RCP 8.5. Moreover, basin runoff will increase by 6.4% under RCP 4.5 and 11.6% under RCP 8.5. The results indicate that the central and southern sub-basins made the most significant contribution to floods in the baseline period, while the eastern sub-basins will make the most considerable contribution to future floods.

Geochemical exploration for Li in regional scale utilizing Staged Factor Analysis (SFA) and Spectrum-Area (S-A) fractal model in north central Iran

The main aim of this study was to outline the lithium anomalies by a regional exploration, at an area of 7800 km2, in Semnan province (north central Iran) using the Staged Factor Analysis (SFA) and Spectrum-Area (S-A) fractal model based on stream sediments and rock samples. Results derived via the SFA denote that Li was located in a factor as F2-4 with B, Cs, U and Rb which was utilized for calculation of the threshold values by the S-A method. The F2-4 data were classified by the fractal model for determination of the Li anomalies. Main anomaly for F2-4≥ 1.5 was situated in the SW and northern parts of this region. Furthermore, Li high grades of rock samples were correlated with main F2-4 anomalies. The main anomalies were correlated with geological particulars of Li mineralization types which represent that the main F2-4 anomalies associate with volcanic and tuff units in the SW part, and overlapped with clay minerals in the northern sector of this region. On the other hand, there are proper potential for Li mineralization which is demonstrated by this method.

Improving the performance of rainfall-runoff models using the gene expression programming approach

Abstract In this study, five hydrological models, including the soil and water assessment tool (SWAT), identification of unit hydrograph and component flows from rainfall, evapotranspiration, and streamflow (IHACRES), Hydrologiska Byråns Vattenbalansavdelning (HBV), Australian water balance model (AWBM), and Soil Moisture Accounting (SMA), were used to simulate the flow of the Hablehroud River, north-central Iran. All the models were validated based on the root mean square error (RMSE), coefficient of determination (R2), Nash-Sutcliffe model efficiency coefficient (NS), and Kling-Gupta efficiency (KGE). It was found that SWAT, IHACRES, and HBV had satisfactory results in the calibration phase. However, only the SWAT model had good performance in the validation phase and outperformed the other models. It was also observed that peak flows were generally underestimated by the models. The sensitivity analysis results of the model parameters were also evaluated. A hybrid model was developed using gene expression programming (GEP). According to the error measures, the ensemble model had the best performance in both calibration (NS = 0.79) and validation (NS = 0.56). The GEP combination method can combine model outputs from less accurate individual models and produce a superior river flow estimate.

Late Holocene Climatic Events, the Main Factor of the Cultural Decline in North Central Iran During the Bronze Age

During the Bronze Age, the cultural region of North Central Iran (NCI) suffered a longterm cultural decline, probably due to severe droughts. According to paleoclimate research, during the overall period c. 5.4–3.5 ka BP, four widely observable climatic events occurred at c. 5.3–5.0, 4.9–4.7, 4.2–3.9, and 3.8–3.5 ka BP, and these appear to have caused widespread environmental damage in the Near East. Archaeological evidence of the NCI-region reveals political events that can be associated with the observed climatic variability. Paleoclimate research and archaeological studies can attribute, in combination, the cultural decline of NCI during the Bronze Age to the Late Holocene climate change.

Prevalence and economic impact of cystic echinococcosis and liver fluke infections in slaughtered sheep and goat in north-central Iran, 2008-2018.

Cystic echinococcosis (CE) and liver fluke infections as important zoonotic infections impose a large socioeconomic impact on societies. As an endemic region for these infections, slaughterhouse inspections should be more considered in Iran. This study aimed to analyze the 11-year record of offal condemnation due to CE, fascioliasis, dicrocoeliasis infections in sheep and goat and its economic impact at Alborz slaughterhouse, north-central Iran. The prevalence rate was calculated as the infected organs (as nominator) divided by the slaughtered cases (as the denominator) in each year and month. The annual percent changes was used to determine trends of parasitic diseases over time. The relationship between metrological indexes and the prevalence of parasitic diseases was determined by the linear regression model. Statistical analyses were done using STATA software 14. For an estimate, the economic impact, the total numbers of offal condemnation were calculated. The overall prevalence rate of fascioliasis, dicrocoeliasis, and CE was 0.95%, 2.17%, and 12.74%, respectively. There was a declining trend in the prevalence of fascioliasis and dicrocoeliasis, whereas, the prevalence of CE increased from 7.57% in 2008 to 9.53% in 2018, representing an annual change of + 0.02%. The direct economic impact was estimated at US$ 1,670,977 and US$ 25,148 for liver and lung, respectively. The number of condemned organs due to these infections is noticeable in Alborz Province, north-central, Iran. The high economic impact of these infections showed the necessity of implementing a continuously infected animal's trace-back and disease control in the site of infection.

Preliminary survey of extended-spectrum β-lactamases (ESBLs) in nosocomial uropathogen Klebsiella pneumoniae in north-central Iran

Infections caused by extended-spectrum β-lactamases (ESBLs) producing bacteria, including Klebsiella pneumoniae have increasingly subjected to therapeutic limitations and patients with these infections are at high risk for treatment failure, long hospital stays, high health care costs, and high mortality. The aim of this study was to screen the prevalence of the blaTEM,blaCTX-M and blaSHV ESBL genes in K. pneumoniae strains isolated from nosocomial urinary tract infections (UTIs). During the March 2016 to December 2017, one hundred isolates of K. pneumoniae were collected from urine specimens of patients suffering from nosocomial UTI referred to Khatam Al-Anbia hospital in Shahrud, north-central Iran. All isolates were identified by standard bacteriological tests. The pattern of antibiotic susceptibility was determined according to the CLSI guidelines. The presence of the ESBLs was investigated using the double-disc synergy test (DDST). Polymerase chain reaction technique was used to detect the blaTEM, blaCTX-M and blaSHV genes in DDST positive isolates. Most isolates showed remarkable resistance to tested antibiotics with highest rate against nitrofurantoin (75%) and trimethoprim/sulfamethoxazole (65%). The imipenem was the most effective antibiotic against K. pneumoniae isolates. ESBL phenotype was detected in 50 (50%) of isolates. The prevalence of blaTEM, blaCTX-M and blaSHV genes among 50 ESBLs-positive isolates was 25 (50%), 15 (30%) and 35 (70%) respectively. The blaTEM and blaSHV genes were seen in 25 isolates (50%) simultaneously. The findings of this study indicated the 50% frequency rate of ESBL-producing K. pneumoniae in our geographic region. Since the treatment of infections caused by this bacterium is associated with many limitations, this high prevalence is a warning sign to adopt new control policies to prevent further spread of this microorganism.

Geochemistry and zircon U-Pb geochronology of Miocene plutons in the Urumieh-Dokhtar magmatic arc, east Tafresh, Central Iran

ABSTRACT The Tafresh plutons that include Ahmadabab diorite, Vasfonjerd monzonite, Mehrezamin diorite and Chahak diorite, located to the east of Tafresh city, north-central Iran, are part of Urumieh-Dokhtar magmatic arc. U-Pb dating of zircon grains provides emplacement ages of 22.3 ± 1 Ma for the Ahmadabad diorite, and tightly clustered ages of 22.2 ± 0.2 Ma, 21.3 ± 0.2 Ma, and 21.7 ± 0.4 Ma for Vasfonjerd monzodiorite, Mehrezamin diorite-monzonite, and Chahak diorite-monzonite plutons, respectively. These rocks are metaluminous to weakly peraluminous, calc-alkaline, and characterized by enrichment in light rare earth elements, Nb-Ta negative anomalies, and high LILE/HFSE ratios. Tafresh plutonic rocks originated from a parental magma source and experienced different degrees of partial melting. Geochemical signatures of Tafresh plutonic rocks, such as a wide range of Y/Nb (2.7–8.4) and low Zr/Nb (19.5–35.) ratios, Nb/Ta (11.46–18.15), argue for mantle–crust interaction during generation of Tafresh magmas. Relatively low Nb/La ratios further indicate that the lithospheric mantle played a significant role in melt generation. HREE signatures (i.e. decrease Dy/Yb with increasing SiO2) preclude substantial involvement of garnet either in the residue, both during partial melting and fractionation of the magma. The plutons are a product of final stages of subduction-related magmatism prior to the collision between the Arabian and Eurasian tectonic plates.

Benthic Foraminiferal Events of the Qom Formation in the North Central Iran Zone

In order to recognize and verify the lower Miocene deposits and the Aquitanian-Burdigalian boundary, benthic foraminifera from different localities in the north of the Central Iran Zone are considered. These facies-controlled foraminifera are useful for biostratigraphical studies, especially in the absence of planktic foraminifera. We investigated eleven stratigraphic sections of the north and northwest Central Iran Zone, and found datum levels of benthic foraminifera such as Borelis melo curdica, Peneroplis farsensis, Elphidium sp. 14, Meandropsinaanahensis, Meandropsina iranica, and Austrotrillina howchini. The most significant event is the first occurrence of Borelis melo curdica which appears at the beginning of the Burdigalian. Hence, this datum can be helpful to recognize the Aquitanian-Burdigalian boundary.

Ground surface response to continuous compaction of aquifer system in Tehran, Iran: Results from a long-term multi-sensor InSAR analysis

Most of the developed groundwater basins in Iran are subject to land subsidence hazards resulting from the over-extraction of groundwater. Several areas in Tehran, the capital city and a provincial center in north-central Iran, have been reported to be subsiding at different rates. In this study, we present the results of an Interferometric Synthetic Aperture Radar (InSAR) time series analysis of Tehran using different SAR data between 2003 and 2017. By constructing more than 400 interferograms derived from 39 Envisat ASAR (C-band), 10 ALOS PALSAR (L-band), 48 TerraSAR-X (X-band), and 64 Sentinel-1 (C-band) SAR datasets, we compile displacement time series from interferometric observations using the Small Baseline (SB) technique. Our analysis identifies 3 distinct subsidence features in Tehran with rates exceeding 25 cm/yr in the western Tehran Plain, approximately 5 cm/yr in the immediate vicinity of Tehran international airport, and 22 cm/yr in the Varamin Plain to the southeast of Tehran city. The temporal pattern of land subsidence, which is dominated by a decreasing trend, generally follows the regional decline in groundwater level, which suggests that anthropogenic processes caused by excessive groundwater extraction are the primary cause of land subsidence. Integrating a decadal time series of subsidence constructed from multi-sensor InSAR with in-situ observations suggests that inelastic and permanent compaction dominates the main deformation regime of the Tehran aquifer, and the ratio between elastic and inelastic deformation is approximately 0.4. A geological analysis indicates that the shape of the subsidence bowl in the western Tehran Plain does not follow the trend of major mapped faults in the region. In contrast, the subsidence bowl in Varamin is controlled by the Pishva Fault, which suggests that either this fault acts as a hydrologic barrier to the groundwater flow in this region or that the differences in sediment thickness causes the discontinuity in land subsidence.

Zeolites filling cavities and amigdales of basic volcanic rocks in NW of Davazdah-Emam mountain, north Central Iran

Zeolites filling cavities and amigdales of basic volcanic rocks in NW of Davazdah-Emam mountain, north Central Iran

Crust-mantle interaction inferred from the petrology and Sr-Nd-Pb isotope geochemistry of Eocene arc lavas from the Kahrizak Mountains, north-central Iran

The Eocene volcanic rocks from the Kahrizak Mountains in north-central Iran are part of the Urumieh-Dokhtar magmatic arc, which runs parallel to the Main Zagros Thrust segment of the Neo-Tethys suture. These volcanic rocks, similar to those from eastern Pontides and northern Anatolia, Turkey, were mainly produced during the Eocene magmatic flare-up associated with the Arabia-Eurasia convergence. The rock suite includes basalt, trachyandesite/andesite and trachydacite/rhyolite lavas and pyroclastic deposits that evolved compositionally from calc-alkalic to shoshonitic. Their normalized trace element concentration patterns are moderately enriched in light rare earth element and depleted in high field-strength elements (HFSE; e.g., Nb, Ta, Ti). They have narrow ranges of initial Pb isotopic ratios and 143Nd/144Ndi, but highly variable 87Sr/86Sri. The new analyses indicate that the parental magmas of the volcanic rocks were derived from a mantle source that had been enriched by fluids released from a subducted oceanic slab. The fluids introduced significant amounts of large ion lithophile elements, but negligible HFSE to the source. The parental magmas underwent fractional crystallization and assimilation of upper crustal materials to produce the range of volcanic rocks. Integration of new analyses with regional data suggests that the Eocene volcanic rocks from north-central Iran, together with ~coeval volcanic rocks in eastern Pontides and northern Anatolia, were most probably derived from a lithospheric mantle source that had been previously metasomatized by fluids derived from a subducted slab before and during the Arabia-Eurasia collision.