West-central Iran Research Articles

Maximizing Sustainability in Reservoir Operation under Climate Change Using a Novel Adaptive Accelerated Gravitational Search Algorithm

Holding a lasting balance between the water resources and water demands has become a challenging task for water resources managers, especially in recent years with the looming global warming crisis and its resulting climatic change effects. This paper focuses on modeling the optimized operation of the Zayandehrud Reservoir, located in west-central Iran, under two fifth-generation climate change scenarios called RCP4.5 and RCP8.5. A novel variant of the gravitational search algorithm (GSA), named the adaptive accelerated GSA (AAGSA) is proposed and adopted as the optimizer of the reservoir operation in this paper. The major advancement of the AAGSA against the original GSA is its high exploration capability, allowing the proposal to effectively tackle a variety of difficulties any complex optimization problem can face. The goal of the optimization process is the maximization of the sustainability of supplying the downstream water demands by the reservoir. The optimal results obtained by the original GSA and the proposed AAGSA algorithms suggest that the AAGSA can achieve much more accurate results with much less computational runtime, such that the proposed AAGSA is able to achieve the reservoir operation sustainability index of 98.53% and 99.46%, under RCP4.5 and RCP8.5 scenarios, respectively. These figures are higher than those obtained by the original GSA by 23.5% and 16% under RCP4.5 and RCP8.5, respectively, while the runtime of the proposal is reduced by over 80% in both scenarios, as compared to the GSA, suggesting the high competence of the proposed AAGSA to solve such a high-dimensional and complex real-world engineering problem.

Fusion of ASTER satellite imagery, geochemical and geology data for gold prospecting in the Astaneh granite intrusive, West Central Iran

ABSTRACT In this study, ASTER imagery, geochemical, lithological, and structural data are exploited for Mineral Potential Mapping (MPM) of the Astaneh granitic pluton and its surrounding area. The independent component analysis (ICA) and Matched Filtering (MF) techniques are applied to ASTER data for detecting alteration mineral assemblages. Sericitically argillically altered minerals associated with jarosite and chlorite/epidote are mapped using the ICA technique. MF fraction images derived from n-dimensional visualisation (n-DV) tool facilitated detecting goethite, haematite, limonite, muscovite, kaolinite, illite, chlorite and epidote associated with gold occurrences. The distribution of Cu, Pb, Zn and Au is considered for generating geochemical anomaly layers. Strong Cu, Zn and Au anomalies are found to be associated with gold mineralisation. The lithological units hosting gold mineralisation and intersection of NE–SW and NW–SE trending lineaments are also considered. Fuzzy Logic Model (FLM) was used to generate gold prospectivity map for the study area by fusing the alteration, geochemical, geology and structural layers. Several high prospective zones are identified in the central and southeastern part of the study area. A majority of delineated exploration targets are either linked to the plutonic body or its surrounding metamorphic rocks. This study demonstrated a viable approach for future gold prospecting in the study area.

Assessment of the management scenarios for groundwater quality remediation of a nitrate-contaminated aquifer.

Nitrate contaminant degrades groundwater quality and threatens the health of the humans, livestock, and the environment. Damaneh-Daran aquifer is located at upstream of the Zayandehrood reservoir in west-central Iran. This aquifer has been highly contaminated by nitrate and is still rapidly being contaminated. Thus, its quality needs to be remediated. This paper is focused on the quantity-quality modeling to predict the average nitrate concentration of the aquifer. Several remediation scenarios are presented in a period beginning from fall 2019, ending in spring 2024. These scenarios address several ways to mitigate the injection of the major sources of contamination in the region, such as equipping the urban regions with wastewater collection and treatment plants and reducing the fertilizers' use. The decreased use of the fertilizers may be achieved through two strategies: directly reducing the amount of the fertilizers by several specific and predefined rates of reduction and indirectly decreasing the amount of the fertilizers used by crop pattern modification. The latter strategy is evaluated to replace all or a part of the areas allocated to the more fertilizer-demanding crops with those of the less fertilizer-demanding crops. Furthermore, some of these scenarios are hybridized to more mitigate groundwater quality degradation. The results of performing the proposed scenarios are once compared together and then compared with the trend scenario letting current case study conditions and facilities be held in the future. The results suggest that the scenario hybridizing the effects of the wastewater treatment plants-equipping scenario with those of the quality-enhancing crop pattern modification scenario is evaluated as the most effective and best-performing scenario, implementation of which offers 20% and 30% reduction of the nitrate concentration for the agricultural and urban areas, respectively.

F-MOPSO/Div: an improved extreme-point-based multi-objective PSO algorithm applied to a socio-economic-environmental conjunctive water use problem.

In this paper, a new version of the multi-objective particle swarm optimizer named the Diversity-enhanced fuzzy multi-objective particle swarm optimization (f-MOPSO/Div) algorithm is proposed. This algorithm is an improved version of our recently proposed f-MOPSO. In the proposed algorithm, a new characteristic of the particles in the objective space, which we named the "extremity," is also evaluated, along with the Pareto dominance, to appoint proper guides for the particles in the search space. Three improvements are applied to the f-MOPSO to mitigate its shortcomings, generating f-MOPSO/Div: (1) selecting the global best solution based on the diversity of the extreme solutions, (2) impeding the particles to be trapped in the local optima using a mutation scheme based on the dynamic probability, and (3) removing the pre-optimization process. To validate f-MOPSO/Div, it was compared with some other popular multi-objective algorithms on 14 standard low- and high-dimensional test problem suites. After the comparative results indicated the outperformance of the proposal, the f-MOPSO/Div was applied to solve an optimal conjunctive water use management problem, in a semi-arid study area in west-central Iran, over a 13-year long-term planning period with two main objectives: (1) maximizing the aquifer sustainability as an environmental goal, and (2) maximizing the crop yields as a socio-economic goal. As the results suggest, the cumulative groundwater level drawdown is considerably decreased over the whole planning period to make the aquifer sustainable, while the water productivity is held at a desirable level, demonstrating the superiority of the f-MOPSO/Div when also applied to solve a large-scale real-world optimization problem.

Translation of the Words of ʿAli b. Abi Tālib in Early Fourteenth-Century Iran: A Local Bilingual Network

The late Ilkhanid period saw a florescence of intellectual and cultural production in northwestern and west-central Iran. This article argues that a regional network with its center at Isfahan contributed to this creativity through the production of translation-adaptations between Arabic and Persian. In a period of episodic sectarian tensions, especially in the wake of Öljeytü’s efforts to declare Twelver Shiʿism the official religion of parts of ʿIraq-e ʿAjam, this local network produced a set of five bilingual treatments of parts of the literary legacy of ʿAli b. Abi Tālib (d. 40/661). The article argues that the authors and copyists of these texts sought, through their focus on the figure of ʿAli and their exploration of the ambiguities facilitated by bilingual composition, to expand a non-sectarian middle-ground.

Variability of 137Cs inventory at a reference site in west-central Iran

137Cs technique has been widely used for the evaluation rates and patterns of soil erosion and deposition. This technique requires an accurate estimate of the values of 137Cs inventory at the reference site. This study was conducted to evaluate the variability of the inventory of 137Cs regarding to the sampling program including sample size, distance and sampling method at a reference site located in vicinity of Fereydan district in Isfahan province, west-central Iran. Two 3 × 8 grids were established comprising large grid (35 m length and 8 m width), and small grid (24 m length and 6 m width). At each grid intersection two soil samples were collected from 0 to 15 cm and 15–30 cm depths, totally 96 soil samples from 48 sampling points. Coefficients of variation for 137Cs inventory in the soil samples was relatively low (CV = 15%), and the sampling distance and methods used did not significantly affect the 137Cs inventories across the studied reference site. To obtain a satisfactory estimate of the mean 137Cs activity in the reference sites, particularly those located in the semiarid regions, it is recommended to collect at least four samples along in a grid pattern 3 m apart.

Conjunctive use of surface and ground water resources using the ant system optimization

Conjunctive use of surface and ground water resources forms an important part of integrated water resource planning and management in a basin-wide scale. This paper presents a simulation/optimization model based on artificial neural networks (ANNs) and an ant system optimization (AS) for solving the monthly conjunctive supply of irrigation water. The study area is Najafabad Plain located in the semi-arid west central Iran. The water resources in the region are under increasing pressure to meet the growing irrigation water demand despite the dire decline in its surface water resources due to climate changes. The main objective of the conjunctive use model developed in this study is to minimize the water deficit in the three irrigation zones subject to constraints on groundwater levels and cumulative drawdown for each zone. The results indicate that the simulation model is capable of predicting the behavior of the study aquifer and that it may be used as a decision support system. Moreover, both the simulation and the optimization models are found capable of determining water extraction quantities required so that not only will the present water deficit decline but aquifer conditions will improve as well.

The first study of bovine immunodeficiency virus (BIV) and brucellosis co-infection in west-central Iran

Background: BIV is a well-known bovine immunosuppressive cause, but its pathogenesis has not been well characterized. In recent years, it has been hypothesized that infection with BIV might predispose cattle to be infected by other agents. OBJECTIVE: This study was performed to investigate of BIV and Brucella co-infection so that in the future more studies will be done on the issue of predisposing cattle to other microorganisms like Brucella after BIV infection. METHODS: Blood samples were collected from a total of 2290 cattle in Iran (490 and 1800 cattle in non-industrial and industrial dairy farms, respectively from Isfahan and Chaharmahal and Bakhtiari provinces). The BIV-positive animals were detected by Lab-ELISA and nested PCR tests. RESULTS: In this study, the overall prevalence of BIV in Iran was 1.61% (4.5% and 0.83% in non-industrial and industrial dairy farms, respectively). CONCLUSIONS: There was a statistically significant relationship between BIV status and Brucella infection using Chi square and Pearson’s correlation coefficient test for all of the samples (p=0.0001, r=0.24), samples from Chaharmahal and Bakhtiari (p=0.044, r=0.13) and from industrial farms in Isfahan (p=0.001, r=0.074).

Vertical lithogeochemical halos and zoning vectors at Goushfil Zn–Pb deposit, Irankuh district, southwestern Isfahan, Iran: Implications for concealed ore exploration and genetic models

The vertical lithogeochemical halos of indicator elements in host rocks over a blind Zn–Pb deposit are developed by upward migration of geochemical halos. This may prove to be a useful exploration guide for targeting undiscovered Zn–Pb mineral systems. The main objective of this investigation is to assess the vertical distribution patterns of the composite lithogeochemical halos for detecting possible exploration guides as well as a possible genetic model of Zn–Pb sulfide mineralization. The Goushfil Zn–Pb deposit is one of the most important Lower Cretaceous carbonate and shale-hosted deposit in the Irankuh district, west-central Iran. The deposit contains about 4.3 million tonnes of sphalerite-galena-barite ore with an average grade of 8% Zn and 2.4% Pb. In order to examine the exploration significance of the vertical lithogeochemical halos, about 274 rock samples from 26 boreholes were sampled and analyzed by ICP-MS for a multi-element package. The results demonstrate that the highly anomalous values for Ag 0.1–120ppm, As, 3–1165ppm, Ba 9–2820ppm, Ca 0.07–25%, Cd 0.005–210ppm, Hg 0.9–24ppm, Mg 0.03–11.75%, Pb 15–15,000ppm, Zn 65–15,000ppm and Sb 1–305ppm are developed in faulted-or fracture-controlled hydrothermally dolomitized and jasperoid carbonates and shales. The newly proposed multiphase composite geochemical halos defined by ratios of (Ag×Cd)/(Pb×Zn), (Ag×As)/(Pb×Zn), (Ca×Mg)/(Pb×Zn), (Sb×As)/(Pb×Zn), (Hg×Sb)/(Pb×Zn), (Sb×Ba)/(Pb×Zn) and (Ba×Ca)/(Pb×Zn), correlate with three exploration zones at the average depth of 10, 200 and 310m above and below the main ore zone. All the composite lithogeochemical halos, in particular (Ag×Cd)/(Pb×Zn) in both rock and soil samples tend to increase toward the shallow depths, but decrease as they approach the main Zn–Pb ore toward the deeper parts of the ore zone. This geochemical response of the composite halos could be used for targeting undiscovered Zn–Pb sulfide mineralization. The low contents of Cu and Fe in the mineralized rocks indicate a low modal content of chalcopyrite and pyrite in the precursor sulfide ore, which correlate with those of the Mississippi Valley Type (MVT) Zn–Pb deposits. This is also highlighted on the log (Pb+Zn)–Pb/Pb+Zn, Cu+Pb+Zn–Cu and homogenization temperature-salinity variodiagrams, on which the Goushfil data plot close to the MVT-type Zn–Pb mineralization.

Composite soil-geochemical halos delineating carbonate-hosted zinc–lead–barium mineralization in the Irankuh district, Isfahan, west-central Iran

The Irankuh district in west-central Iran hosts several largely unexposed Lower Cretaceous carbonate-hosted Zn–Pb deposits whose host rocks are overlain by soil cover. This paper documents a detailed soil-geochemical exploration program, comprising 804 residual soil samples that were treated with a microwave acid digestion and analyzed by ICP-MS for a multi-element package. The soils overlying the Zn–Pb–Ba veins and mineralized zones have geochemical contrast and element enrichments that are more than two to twenty-one times greater than the non-mineralized background soil values. The most diagnostic elements are Zn, Pb, Ag, Ba, Hg and Sb which show multi-point anomalies across the entire mineralized zone with concentration ranges of 282–10,000ppm Zn, 73–10,000ppm Pb, 2.2–71.9ppm Ag, 1500–3400ppm Ba, 0.89–36ppm Hg and 11–164ppm Sb, respectively. The newly proposed composite geochemical halos defined by Ag*Cd/Pb*Zn, Ag*As/Pb*Zn, Ca*Mg/Pb*Zn, Sb*As/Pb*Zn, Hg*Sb/Pb*Zn, Sb*Ba/Pb*Zn, Ba*Ca/Pb*Zn and Ag*As* Sb/Pb*Zn*Bi correlate well with the anomalous patterns of the individual elements. The anomalies are coincident with the main faults and fractures, in particular Gushfil and Rumarmar faults of the area. On the basis of the low contents of Cu and Fe and the variodiagram of log (Pb+Zn) versus Pb/Pb+Zn, the composition of the samples suggests epigenetic stratabound Zn–Pb–Ba mineralization of the Mississippi-Valley-Type (MVT). The mode of occurrences of the anomalies is likely controlled by structural replacement in sphalerite, galena, carbonates and barite or adsorption by iron–manganese oxides and clay minerals. Follow-up sampling of gossans in highly faulted-fractured zones may indicate more concealed Zn–Pb mineralization.

Mercury levels in common (Actitis hypoleucos) and green (Tringa ochropus) sandpipers from west-central Iran.

Mercury concentrations were examined in the liver, kidneys, and tail and breast feathers of common and green sandpipers from Zayanderud Dam in west-central Iran. The aim was to provide indirect information about habitat contamination. Tail feathers of both species had higher mercury levels compared to other tissues. Moreover, tissues of common sandpipers had significantly higher mercury concentrations compared to tissues of green sandpipers. Male specimens of both species had higher values of mercury compared to females. The pattern of larger body size-higher mercury body burden was not completely true in the current study. Smaller and shorter common sandpipers had higher mercury concentrations compared to taller and heavier green sandpipers. At the intraspecific level, body weight was positively correlated with mercury concentrations in tissues of common sandpipers. Based on the data presented here, it appears that these sandpipers, especially common sandpipers, are at potential risk from the toxic effects of mercury.

Variation of soil microbial biomass C and hydrolytic enzyme activities in a rangeland ecosystem: are slope aspect and position effective?

This study was conducted to investigate the effects of slope aspect and position on microbial biomass C (MBC) and some hydrolytic enzyme activities involved in soil N, P, and S cycles in a rangeland ecosystem of west central Iran. Soil samples were collected from three slope positions (summit, backslope, and footslope) of contiguous north- and south-facing slopes. Results indicated higher silt and clay content, soil organic C (SOC), total N (TN), and C/N ratio on the north-facing slope. Furthermore, MBC, alkaline phosphomonoesterase (ALP), acid phosphomonoesterase (ACP), arylsulfatase (ARS), urease (URS), L-asparaginase (LAS), and L-glutaminase (LGL) activities were greater by 46.1, 65.9, 58.6, 59.6, 52.6, 62.8, and 65.7%, respectively, on the north-facing slope compared to the south-facing one. Higher ratios of enzyme activities to MBC were observed on the north-facing slope. In contrast, per cent of inorganic N and microbial quotient were greater on the south-facing slope. The activity of ALP, ACP, ARS along with SOC, TN, and MBC values decreased from summit to footslope. Overall, our findings indicate that north-facing slope and summit position support greater microbial biomass and hydrolytic diversity.

Numerical modelling of the groundwater inflow to an advancing open pit mine: Kolahdarvazeh pit, Central Iran.

The groundwater inflow into a mine during its life and after ceasing operations is one of the most important concerns of the mining industry. This paper presents a hydrogeological assessment of the Irankuh Zn-Pb mine at 20km south of Esfahan and 1km northeast of Abnil in west-Central Iran. During mine excavation, the upper impervious bed of a confined aquifer was broken and water at high-pressure flowed into an open pit mine associated with the Kolahdarvazeh deposit. The inflow rates were 6.7 and 1.4m(3)/s at the maximum and minimum quantities, respectively. Permeability, storage coefficient, thickness and initial head of the fully saturated confined aquifer were 3.5 × 10(-4)m/s, 0.2, 30m and 60m, respectively. The hydraulic heads as a function of time were monitored at four observation wells in the vicinity of the pit over 19weeks and at an observation well near a test well over 21h. In addition, by measuring the rate of pumping out from the pit sump, at a constant head (usually equal to height of the pit floor), the real inflow rates to the pit were monitored. The main innovations of this work were to make comparison between numerical modelling using a finite element software called SEEP/W and actual data related to inflow and extend the applicability of the numerical model. This model was further used to estimate the hydraulic heads at the observation wells around the pit over 19weeks during mining operations. Data from a pump-out test and observation wells were used for model calibration and verification. In order to evaluate the model efficiency, the modelling results of inflow quantity and hydraulic heads were compared to those from analytical solutions, as well as the field data. The mean percent error in relation to field data for the inflow quantity was 0.108. It varied between 1.16 and 1.46 for hydraulic head predictions, which are much lower values than the mean percent errors resulted from the analytical solutions (from 1.8 to 5.3 for inflow and from 2.16 to 3.5 for hydraulic head predictions). The analytical solutions underestimated the inflow compared to the numerical model for the time period of 2-19weeks. The results presented in this paper can be used for developing an effective dewatering program.

Mineralization and structural features of Kalchouyeh copper-gold deposit (west-central Iran)

The Kalchouyeh copper deposit is located about 110 km east of Isfahan, in the Urumieh-Dokhtar magmatic assemblage (UDMA) arc of Iran. Mineralization is closely associated with the calc-alkaline volcanism of the UDMA arc and controlled by northwest–southeast trending strike-slip faults (Qom-Zefreh and Nain-Baft faults). A pull-apart basin along these strike-slip faults has facilitated the localization of magma and related hydrothermal systems and eventually the development of Kalchouyeh mineralization. Copper mineralization occurs mainly as veins and veinlets and is related to two distinct main stages of hypogene and supergene. Hypogene mineralization includes Cu and Pb sulfides (chalcopyrite, pyrite, galena) and Fe oxide (magnetite). Chalcocite and covellite are found in supergene mineralization. Microthermometric measurements of fluid inclusions on two mineralized veins show the presence of two different kinds of ore fluids: (1) low temperature and salinity in relation to vein A (homogenization temperature 175–252 °C, salinity 0.82–4.23 wt.% NaCl) and (2) low to moderate temperature and salinity in relation to vein B (homogenization temperature 255–324 °C, salinity 0.16–9.32 wt.% NaCl). Copper mineralization at Kalchouyeh appears to be epithermal and low-sulfidation in style, and ore deposition was the result of cooling and surface fluid dilution.

Integrated Index for Assessment of Vulnerability to Drought, Case Study: Zayandehrood River Basin, Iran

Drought is an extended period of deficient precipitation that causes damage to crops and reducing their performance, causes temporary scarcity of water for human/livestock consumption. Over the years, various indices have been proposed to identify onset, characterize and quantify the attributes of meteorological, hydrological and agricultural drought by various researchers. Because of the spatial and temporal variability and multiple impacts of drought, it is necessary to develop an integrated index for assessment of vulnerability of this natural phenomenon. The aim of this paper is presenting an integrated index for assessment of vulnerability to drought using multiple factors which includes hydrological, meteorological, land use and other factors. Spatial information of various factors was categorized in to various sub-classes and maps were prepared in spatial domain using Geographic Information System (GIS). This study has been carried out in the Zayandehrood River basin located in west-central Iran with semi-arid region. Due to continue droughts at recent decade, this area has been chosen as a case study. The long-term climate data (1991–2011) used for assessment. The results show that Zayandehrood River basin has experienced 11 dry years, 4 normal years, and 6 wet years in the 21 years. The results have been validated with intensive field surveys.

Upper Albian and Cenomanian (Cretaceous) ammonites from the Debarsu Formation (Yazd Block, Central Iran)

ABSTRACT Wilmsen, M., Storm, M., Fürsich, F.T. and Majidifard, M.R. 2013. Upper Albian and Cenomanian (Cretaceous) ammonites from the Debarsu Formation (Yazd Block, Central Iran). Acta Geologica Polonica, 63 (4), 489-513. Warszawa. New ammonite faunas consisting of 13 taxa provide the first reliable biostratigraphic dating of the Debarsu Formation of the Yazd Block, west-central Iran, indicating several levels in the Upper Albian and Lower Cenomanian, while a foraminiferal assemblage places the top of the Formation in the Middle Turonian. Among the identified ammonite taxa, Acompsoceras renevieri (Sharpe, 1857) is recorded from Iran for the first time. The upper part of the lower Upper Albian is proved by the occurrences of mortoniceratines of the Mortoniceras (M.) inflatum Zone in the lowermost part of the Debarsu Formation. For the upper Upper Albian (traditional Stoliczkaia dispar Zone), the M. (Subschloenbachia ) rostratum and M. (S.) perinflatum zones are proved by their index taxa. However, there is no evidence of the terminal Arrhaphoceras (Praeschloenbachia) briacensis Zone. The upper part of the lower Lower Cenomanian Mantelliceras mantelli Zone (M. saxbii Subzone) is proved by M. saxbii and M. cf. mantelli. Below, there is an ammonite- barren interval of ca. 100 m in thickness between M. (S.) perinflatum zonal strata and the M. saxbii Subzone. The upper Lower Cenomanian is documented by the presence of typically M. dixoni zonal ammonites such as Acompsoceras renevieri. Upper Cenomanian and Turonian ammonites have not been found in the upper part of the Debarsu Formation, but micro-biostratigraphic evidence (planktonic foraminifers) from the uppermost part of the formation indicate that the formation ranges into the Turonian. For the development of the major tectonic unconformity at the base of the overlying Haftoman Formation (which yielded Lower Coniacian inoceramids near its base), only 2-3 myr remain, stressing the geodynamic activity of Central Iran during mid-Cretaceous times.

Conjunctive Use of Surface Water and Groundwater: Application of Support Vector Machines (SVMs) and Genetic Algorithms

Combined simulation-optimization models have been widely used to address the management of water resources issues. This paper presents a simulation-optimization model for conjunctive use of surface water and groundwater at a basin-wide scale, the Zayandehrood river basin in west central Iran. In the Zayandehrood basin, in the past 10 years, a historical low rainfall in the head of the basin, combined with growing demand for water, has triggered great changes in water management at basin and irrigation system level. The conjunctive use model that coupled numerical simulation with nonlinear optimization is used to minimize shortages of water in meeting irrigation demands for four irrigation systems. Constraints guarantee the maximum/minimum cumulative groundwater drawdown and maximum capacity of irrigation systems. A support vector machines (SVMs) model is developed as a simulator of surface water and groundwater interaction model while a genetic algorithm (GA) is used as the optimization model. Conjunctive use model runs for three scenarios. Results show that the accuracy of SVMs as a simulator for surface water and groundwater interaction model is good and that it is possible to decrease the water shortage for irrigation systems with application of proposed SVMs-GA model.

History of faulting on the Doruneh Fault System: implications for the kinematic changes of the Central Iranian Microplate

AbstractThe Doruneh Fault System is one of the major transcurrent faults in central Asia, extending ~900 km from western Afghanistan into West-Central Iran. The left-lateral Doruneh Fault System is also a key structure in the Arabia–Eurasia collisional zone, bounding the northern margin of the independent Central Iranian Microplate. The Doruneh Fault System exhibits a curved geometry, and is divided here into three segments: Eastern, Central and Western. We present the results of geological, structural and geomorphic studies into the nature of recent activity along the Doruneh Fault System segments. A surprising observation is that small, relatively young drainage systems often show recent systematic left-lateral displacement across the fault, whereas large rivers indicate a former more complex right-lateral history. Furthermore, the existence of right-lateral offsets of pre-Pliocene rocks and S-C fabrics confirm this earlier phase of right-lateral movement on the fault. We suggest that the early right-lateral kinematics resulted from an earlier NW–SE-directed regional shortening, associated with the anticlockwise rotation of the Central Iranian Microplate. The shortening is characterized by the NE–SW-striking en échelon folds within the fault slivers, the right-lateral Taknar imbricate fan and the superimposed folding exposed north of Kashmar. Thus, assuming an initiation age of Eocene (55.8 Ma) for the fault, we estimate a former right-lateral slip rate of about 5.2–5.5 mm yr−1, which accompanied the 35° anticlockwise rotation of the Central Iranian Microplate. According to our study, the youngest units exhibiting right-lateral displacement are Middle Miocene in age, suggesting a post-Middle Miocene timing for the onset of slip-sense inversion.

Magnetic susceptibility and Cs-137 inventory variability as influenced by land use change and slope positions in a hilly, semiarid region of west-central Iran

The objective of this study was to explore the slope position and land use change effects on the variability in magnetic susceptibility and 137Cs inventory as the soil redistribution indicators in a hilly semiarid calcareous area in Iran. The selected study area is located in a hilly region with pasture and cultivation land use of Fereydunshahr, Isfahan Province in west-central Iran. In the two mentioned dominant ecosystems, four slope positions including summit, shoulder, backslope and footslope were identified and in each land use and slope position, three cores were selected to collect 72 soil samples from three depths (0–10, 10–20, 20–30 cm) in an area of 15 × 15 cm. Additional 28 soil samples were collected from the reference site for soil loss and deposition calculations by using the Cs-137 measurement. The results of the study with the use of the Cs-137 technique showed that the average soil loss in the pasture land (46.4 t ha− 1 yr− 1) was significantly (p < 0.05) lower than the average soil loss in the cultivated land (80.4 t ha− 1 yr− 1). The highest soil loss in both land uses was obtained in the shoulder position, 60.1 and 84.4 t ha− 1 yr− 1, respectively, for the pasture and cultivated lands. Moreover, the highest rates of soil deposition was observed in a footslope position in both land uses and they were 34 and 32.4 t ha− 1 yr− 1 for the pasture and cultivated lands, respectively. Magnetic susceptibility was significantly (p < 0.05) greater in pasture (χlf = 41.51 × 10− 8 m3/kg) than in the cultivated land (χlf = 34.90 × 10− 8 m3/kg). The pasture land with a lower soil loss rate, indicated significantly higher magnetic susceptibility in all landform positions as compared to that in the cultivated land. The results of the correlation analysis showed that among the studied soil physico-chemical properties, χlf (r = 0.83, p < 0.01) in the pasture land had the highest correlation with the Cs-137 inventory. Throughout the non-linear regression analysis, χlf was introduced for relating soil parameters and the cesium inventory explained 68% and 79% of the total variability of 137Cs in the pasture and cultivated lands, respectively. The results implied that the variability in the magnetic susceptibility within the hillslope is consistent with the variation of the Cs-inventory; and the results thus demonstrate the slope and land use effects on soil redistribution.

Geochemistry and zircon geochronology of the Permian A-type Hasanrobat granite, Sanandaj–Sirjan belt: A new record of the Gondwana break-up in Iran

The Sanandaj–Sirjan metamorphic–plutonic Belt (SSB) in west central Iran is a polyphase metamorphic terrain composed of dominantly greenschist-grade metasedimentary and metavolcanic rocks, and felsic to mafic plutons, of Neoproterozoic–Phanerozoic ages. The Hasanrobat granite in central SSB occurs as a single pluton, ~20km2 surface area, with relatively consistent mineralogy and chemistry. Quartz, alkali feldspars (microcline and perthite), sodic plagioclases and biotite are the main constituents, commonly associated with minor amphibole. Accessory phases include zircon, allanite, apatite, and magnetite.The country rocks are Upper Carboniferous–Lower Permian sandstones and dolomitic limestones. Scattered patches of skarn-type assemblages dominated by tremolite and talc occur in the dolomitic limestones, and sandstones are recrystallized to a coarse-grained quartzite at contact with the granite. The granite is metaluminous to slightly peraluminous, and is distinguished by high FeOt/MgO ratios, typical of ferroan (A-type) granites. The A-type affinity is also reflected by high Na2O+K2O, high Ga/Al ratios, high contents of large ion lithophile elements (LILE), high field strength elements (HFSE) and rare earth elements (REE), as well as low contents of Sr, and distinct negative Eu anomalies. The biotites are aluminous, Fe-rich, and plot near the siderophyllite corner in the quadrilateral biotite diagram. They are further distinguished by high fluorine contents (0.61 to 1.33wt.%). Amphibole is ferrohastingsite in composition. Ion microprobe analyses of zircon grains separated from a representative granite sample yielded concordant U–Pb ages with weighted mean 206Pb/238U age of 288.3±3.6Ma.The granite and the country rocks are cut by a set of mafic dykes with asthenosphere-like geochemical signatures. Such association suggests anorogenic intraplate magmatism in Lower Permian in the region. This provides further evidence for, and significantly constrains timing of, a major extension in Upper Paleozoic in Iran, previously inferred from the rock record. The extension led to the Gondwana break-up and the opening of Neotethys Ocean between Sanandaj–Sirjan and Zagros in Permian.