GEOSCIENCES
Year:2015 | Volume:24 | Issue:94 (ENGINEERING & ENVIRONMENTAL GEOLOGY)|Papers Count:24

The hydraulic fracture process is commonly used in the production of oil and natural gas reservoirs as a means of increasing well productivity and extending the production lifetime of the reservoir. The productivity of a hydraulically fractured oil or gas well is directly related to how well the well bore is connected to the fracture. Some rock formations contain natural fracture systems that can further increase a well’s productivity, provided that the generated hydraulic fracture can grow such that these natural fractures. In this paper, at the first, a conventional area with productive formation and its surrounding layers were defined and then by use of finite element method the simulation was executed. The results indicated that a correct fracture generation will increase the production and efficiency. It is clear that this study is applicable for real data.

Ground assessment to identify and map of susceptible land are as to slope movements especially landslides is of studies related to natural geographers, particularly geomorphologists. Determining and recognition of susceptive areas to sliding could prevent making loss as well as facilitating slope stability operations. In this study, the variables such as slope, the aspect of slope, petrology, land use, rainfall, and distance from river, fault, and road were used to map the risk of landslide in the Taleghan watershed. After constructing and analyzing the information layers by means of Arc GIS Software, the fuzzy membership functions were used for weighting the layers. The standardized fuzzy layers were overlapped in GIS environment and the landslide risk mapping was produced by means of fuzzy logic operators. The results of this study indicated that gamma function 0.7 is more appropriate than other fuzzy operators. Based on the abovementioned gamma, 18.91% of the area was identified as the high-risk areas. Obviously, allocating these areas for housing, facilities, etc. increases financial and physical damages.

In this study, engineering geomorphology of Mashhad City is evaluated. For this purpose, aerial photos of the city, 180 drinking water wells and 1500 scattered geotechnical boreholes have been studied. Based on this information, the city divided into 6 geomorphologic units including rock outcrop, pediment, Golestan fan, Torough fan, southern fans and flat plain. Then, engineering geology properties of these units were investigated based on the geotechnical data sets. The geotechnical properties were evaluated just for the upper 10m of deposits. The results show predominant soil in the pediment and southern fans units is gravel, sandy and gravely soils are predominant in the Golestan fan unit, whereas clay and sand are predominant soils in the Torough fan and flat plain. In this study, earth evaluation was carried out based on the standard penetration test that shows the pediment unit has more resistance than other units. The clay minerals were determined based on the activity chart. Smectite and kaolinite are predominant clay minerals in the pediment and flat plain units, respectively.

Accurate and up-to-date spatial data play a crucial role in disaster management. However, currently utilization of spatial data in decision making process before, during and after disasters is limited due to various problems. Automatic composition of geospatial web services can significantly improve the decision making process in disaster management. This article is going to represent an approach for utilization of automatic web service composition in disaster management. In this approach, geospatial web services of different organization are syntactically and semantically described and registered in the national geoportal. The services are composed based on user requirement using Artificial Intelligence Planning algorithms. The new composite web services are registered as new geospatial web services. The applicability of the approach is illustrated in a case study for generating a composite web service that can build landslide susceptibility map.

Due to the fast urban developing and construction of surface and sub-surface structures such as several subway lines, requiring the geotechnical studies on these structures is increasingly emphasized. The metropolitan Tehran, in south of the Central Alborz, lying on the set of Quaternary alluvial deposits and surrounded by the active seismic faults such as the Northern Tehran fault in the north and the Parchin and Pishva faults in the south requires investigations to determine the bilateral relationship between seismic potential of the peripheral active faults andthe geotechnical characteristics of the alluvial deposits. In this study, using field and laboratory data, geotechnical characteristics of the deposits, material of soil horizons, and different parameters of them along the 27 km length of Tehran 7th subway line have been studied by provided software to calculate: bearing capacity, settlement and liquefaction potential. Based on this study, the members C and D of the Tehran alluvial deposits has relatively high resistance value and measured settlement in all areas is limited to 2.5 cm. The data of SPT indicate any likely occurrence of liquefaction of sand layers in the east - central Tehran during a seismic event.

Over the last few decades, many studies have been resulted in landslide susceptibility maps using different techniques including the probability method (frequency ratio), the Analytical Hierarchy Process (AHP), bivariate, multivariate, logistic regression, fuzzy logic and artificial neural network (ANN). This study aimed to evaluate the susceptibility of the occurrence of landslides in the Vazroud watershed located in Mazandaran Province, north of Iran. The achieved results were based on three methods of frequency ratio model, statistical index (Wi) and weighting factor (Wf), which integrated to Geographical Information System (GIS) and remote sensing techniques. Vazroud as mountainous watershed morphologically is with increasing occurrence of landslides and it caused many failures of the mass movement, which seem continues now. In order to reduce the effects of this occurrence, it is necessary to scientifically assess the area where are susceptible to the landslide. For this reason, landslide susceptible areas were mapped and the landslide occurrence parameters were analyzed using three different methods. The results of these analyses were confirmed using the relative operating characteristics curve (ROC). The validation process showed that the value for the area under the ROC curve for the Wf method was found to be 0.962, with an estimated standard error of 0.002 and is better in prediction than the other methods of frequency ratio and the statistical index (Wi) model.

With detection of the magnetic minerals along with the chromite, it is possible to prospect the chromite deposits. Chromite has no magnetic properties but from the genetic aspects, there is a close relation between chromite and magnetite. With this respect and the magnetic differences of chromite minerals with the country rocks, the effort was to prospect the chromite mineralization of 1: 50000 Abdasht sheet by the use of air born geophysical data. In the study of the geophysical air born of the area, the observed magnetic piles in the area has been investigated by using of the digital filters of reduce to pole, first and second derivations, analytical signals and upwards continuation on the map of the magnetic field of the total intensity. With the study of these maps and compare them with the area, especially ophiolite and ultramafic bodies and chromite-included areas have been studied and the final results are compared with the magnetic pattern and with respect to the maps of the vertical derivation and upwards continuation, 25 areas for the detailed exploration and field sampling area suggested in the entire sheet of the Abdasht.

The Scalar controlled-source audio magneto tellurics (CSAMT) survey was carried out over the Xiangxi Au-Sb-W deposit and 237 sites in eight lines were acquired. The Lines were designed in NS direction to acquire data in TM mode approximately perpendicular to general trend of the area’s structures. The survey produced apparent resistivity contour maps at ten frequencies: 8, 16, 32, 64, 128, 256, 512, 1024, 2048, and 4096. The CSAMT data provided important information about mineralized layers and structures in the study area so that along with detection, mapping and defining parameters of some mineralized zones, detection of some faults were made possible. Follow-up detailed geological mapping and drilling results verified most of the results of the work.

Nowadays GIS techniques are used as a conventional tool for integrating geographic information datasets. In these methods, integration is done according to quality and quantity of datasets and using appropriate weighting approaches. Finally, with Classification methods like Geometric Distances, Mineral Potential Maps (MPM) is produced. By increasing application in data processing, clustering methods classify samples into groups by similarity between them. In this paper, K_ Means and Fuzzy K_ Means clustering methods are discussed for mapping potential zones of Gold mineralization, then the results are compared with GIS method, Index Overlaying, for the Barika area in 1:100,000 Alut Sheet in South of Azerbaijan. In the Barika area, information of drilling points aren’t available, so it’s not possible to determine number of classes and boundaries of each class for final score map, but in clustering methods, the optimum number of class for output map is done automatically and is tested for the Barika Anomaly data. The results show that clustering methods need no weighting and it’s possible to use it with low information than GIS_ based method. The results also show that both of approaches, clustering methods and Index overlaying, display almost an equal area for the most potential zone, however clustering methods need low information for analyzing, but in Index overlaying, it is needed to have more information for weighting and determining threshold for classification of final scores.

Prospecting of deposits by studying of alteration zones has agreat importance. Giventhattheidentificationof alteration zones of areas, which have iron potential has beenlessstudied usingremote sensingdata, thereforeto achievethe identificationofalterationsurrounding the HajiAbadiron deposit in the northeast of Sonqor City,, in the Kermanshah Province processinganalysisofsatellite images such as False Color Composite (FCC), Band Ratio (B.R), Directed Principal Component Analysis (DPCA) and Spectral Angle Mapping (SAM) techniques on short wave infrared and visible near infrared bands (SWIR+VNIR) of ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer sensor) were used. Also by comparing USGS (United States Geological Survey) minerals standard reflection curve with studied region’s curves, it can be seen that the curve of the propylitic alteration minerals have more agreement with chlorite and epidote, and the phyllic-argillic alteration have more agreement with illite and kaolinite, and iron-oxides have more agreement with goethite and hematite. The results accuracy was approved by fieldandmicroscopicstudies and represents the patterns of alteration aroundthedeposit.

Hyper spectral images of Hyperion sensor is a rich source of information with 242 narrow contiguous spectral bands. Among these, there are a number of atmospheric agents, which contaminate the content of various information bands. Therefore, to obtain the complete advantage of a Hyper spectral image in optimum condition, atmospheric correction is an inevitable process. Atmospheric corrections may be conducted by two methods, namely data based, and scene based. In the scene based methods, spectral anomalies are detected and corrected by using self-image spectral information processing without a field information requirement. In this study, two scene based atmospheric correction methods of Quick Atmospheric Correction (QUAC) and Internal Average Relative Reflectance (IARR) were examined on Hyperion image of Masahim volcanic crater. To evaluate the results of these two scenes based methods, the results of field spectroscopy and data based empirical line method were used. X-ray diffraction and spectral analysis of selected samples, whose locations were determined through SAM method, illustrated kaolinite pattern as index mineral of argillic zone. In order to compare the results obtained from different atmospherically corrected images quantitatively, maximum probability pixels obtained from SAM method were evaluated for each corrected images in classified information format. After drawing the accuracy matrix for classified pixels and sampled and investigated pixels in the field and laboratory studies, the accuracy coefficients were calculated for the favorable districts of the corrected images bytwo scene based methods and ELM method. The examination results display the producer accuracy of 74.58 percent for IARR corrected images and a producer accuracy of 35.5 percent for QUAC corrected image; whereas the ELM data based correction method despite using field spectrometry data shows the producer accuracy of 74.58 percent. Therefore, in discrimination of argillic zone in semi-arid regions, IARR atmospheric correction method is considered as suitable and affordable preprocessing method to retrieve spectral information from the hyper spectral data.

The Urmia Lake is one of the old and very important water bodies in Iran. Nowadays, for various reasons, this lake has become an environmental crisis. What is happening today to this lake happened to the Aral Sea not long ago and converts it to a salt marsh with huge damaging environmental effects. Drying of the Urmia Lake has many environmental consequences such as degradation and salination of soils. In this study, using Landsat satellite images, Remote sensing (RS) techniques and GIS software, salt marsh around the lake was studied. First, saline areas were detected in satellite data and then the desired color combinations defined in the ENVI software. At last, after extracting the maps from images, area changes were studied and environmental impacts that will occur due to increased saline lands were studied. In a 13-year study period of Landsat satellite images, the trend shows a very rapid increasing of saline lands. In 1998, an area of salt marsh 28.516 km2 has increased to 744.411 km2 in 2011.This amount is nearly 26 times since 1998. Increasing of the saline lands, lead to the degradation and loss of soil fertility, and if this trend continues itcan lead to areas of fertile land out of agricultural production.

The fractures are one of the structures, which can be used as a tool to unravel the tectonic processes in a region. The measurements of the fractures were conducted in the footwall and hanging wall of the North Neyshabour Thrust, which is one of the active faults of the region. We separated the fractures of the North Neyshabuor Thrust into tow sets of perpendicular and parallel to the fault, which suggests variations in tectonic condition. Clockwise rotation around vertical axis is the recent model, which is proposed for this region. Rotation model noted that the eastern part of NE Iran has been moving towards south and this magnitude increase towards the East. The southward movement of this region is in conflict with regional movement of the Iranian micro plate, which moves to the north. Increasing in elevation towards the east is caused by increasing in the shortening rate. Thus, a decrease in GPS vector towards the east suggests that the movement vector decreases towards the east. This does not indicate a decrease of shortening rate.

The Torud - Chah Shirin volcanic-plutonic complex is located in the western part of Sabzevar Metallogenic Belt and in the south of Moaleman city in the Semnan province. The presence of several mineral occurrences, especially base metal veins of epithermal origin has increased the economic importance of the magmatic complex for geological studies. The intrusion of igneous acidic to intermediate bodies in the volcanic rocks of the area has caused different alternation and mineralization in some parts of the area. In this research, various images processing methods such as false color composites (FCC), band ratios (BR) and spectral angle mapping (SAM) were performed on ASTER L1B VNIR+SWIR dataset, for discrimination of alteration zones in the Torud-Chah shirin magmatic arc. Alteration minerals like kaolinite, illite alunite, pyrophyllite, sericite, chlorite, epidote and calcite, which are associated with argillic, advanced argillic, phyllic and prophyllitic zones were recognized by processing aster dataset and highlighted altered area throughout the range. According to the field studies and XRD analysis, accuracy the results of spectral angle mapping and Band Ratio Logical Operator Algorithms evaluated by confusion matrix and kappa coefficient. Accuracy assessment shows an overall accuracy of 72% and 68% and a kappa coefficient of 0.627 and 0.6 respectively for spectral angle mapping and Band Ratio Logical Operator Algorithms for enhancing argillic and phyllic alteration zones in the study area. Therefore, the results show spectral angle mapping method achieved better results in compared to Band Ratio Logical Operator Algorithms.

The Rayen plain, which is about 1900km2 in area is considered as a part of the Lut drainage basin and is located in the southwest of Lut and eastern slopes of the Hezar Mountain. This plain lies at the 110km southeast of Kerman city. Geographically, it is at 57˚, 13’ to 57˚, 54’ eastern longitude and 29˚, 23’ to 29˚, 52’ northern latitude. The average height of this plain is about 2600m above msl. Given the location of the plain at the vicinity of the Urmiah- Dokhtar volcanic Belt and considering the role of eruptions as well as volcanic rocks and hydrothermal activities on the concentration of arsenic and the role of this element in environmental problems, this study was performed on the concentration of arsenic in groundwater. In order to determine the variations and source of arsenic, in all,29 samples were collected from the water points (springs, qanats and wells).Subsequently, the concentration of As, major cations and anions (Na+, K+, Ca2+, Mg2+, Cl-, SO4-, HCO3-), NO3-, F-, as well as EC, TDS, alkalinity and total hardness were determined. Accordingly, is oconcentration map and correlation diagram were prepared and statistical analysis including Principal Component Analysis (PCA) and Cluster Analysis (CA) were carried out. The arsenic concentration in groundwater of this plain varies from 0.1 ppb up to 248.4 ppb with an average of 21.6 ppb. Based on the statistical analysis, arsenic concentration shows positive correlation with pH. The intrusion of hydrothermal waters into the aquifer and desorption from oxides and hydroxides of iron are considered as the main causes of high-arsenic level in some parts of this plain.

Soil, as one of the important elements of lithosphere and a part of ecosystem plays a crucial role in the life cycle. The goal of the present research was to assess the influence of mineralization and abandoned Ay-ghalasi lead-zinc mine on the distribution of heavy metals and pollution in soil throughout the region. In this regard, 4 soil samples from tailing around the mine and 23 residual soil samples from whole basin, 5 to 20 cm depth, considering the stratigraphy of the region and the distance to the mine were taken. The ICP-OES techniques were employed to determine the concentration of heavy metals (Pb, Zn, As, Cd, Cu, and Ag) in tailing and residual soil samples. The results show that the mean concentration of the heavy metals namely Pb, Zn, As, Cd, Cu, and Ag are 9187.2, 9392.3, 630.8, 0.2, 1005.9 and 61.1 respectively (all in mg/kg), which all are higher than the mean of world soil (MWs) except for the Cd, and also higher than the Dutch standard except for the Ag. In the vicinity of the mine, the concentrations of the metals are high, decreasing with the distance from the mine and the mineral vein. The concentration of Pb, Zn, As, and Ag in the control samples were higher than the MWs and the Dutch standard that is an indication of high background concentration of these elements in the region. In terms of Geo-accumulation Index, Enrichment Factor, Contamination Factor, Contamination Degree, and Pollution Load Index, the soil of the mine area shows high to infinite level of contamination. The elements Pb, Zn, Cu, and Ag have a high Pearson correlation factor.

The anthropogenic and natural contaminants are considered as the main factors threatening water resources and they are in direct connection to the public health and also threaten the development of water resources. The Latyan Dam reservoir is the main source of drinking water of Tehran metropolitan area. In this paper, the environmental geochemistry of water and sediments have been studied. Eight sampling stations were selected in the lake and water samples were taken for measurement of trace elements in dissolved and particulate phases. In addition, sediment samples were taken at the same points by using a grab. The geochemical analysis performed by ICP-OES method showed that the concentration of potentially toxic metals were measured below the detection limit of the instrument and fall in the ranges of safe drinking water guidelines. The sediment samples showed concentrations within the quality guideline values except for As and Pb. The enrichment factor and Igeo were calculated for the sediment samples indicating that the sediments are not contaminated. Metal enrichment in sediments is however very strong compared to water samples and it is suggested that the adsorption processes have important role in sorption of metal contaminants onto the surface of sediment particles and it could be regarded as a potential for contamination if they return to water column in case of change in sediment physicochemical conditions.

The KhoyPlain is located in the north of West Azarbaijan province, northwest of Iran. The study area has a cold and arid climate with the annual mean precipitation of about 344 mm. The purpose of this study is evaluating of hydro chemical properties of groundwater and determination of arsenic contamination at this plain. According to the hydro chemical analysis of 36 collected groundwater samples, in some zones of the area, arsenic contamination is exceed the world health organization (WHO) standard for drinking water. The arsenic concentrations of the water samples were increased in the east and southeast part of the study area. Based on the cluster analysis, the samples were posed in three clusters. Each of the clusters divided into subgroups based on heavy metals contain such as arsenic and iron. There is a positive correlation relationship between arsenic and iron, copper, sodium, chlorine, sulfate and EC. The high correlation of arsenic with iron and copper show the high impact of oxides and hydroxides of these elements in absorbing and accompanying in the sediments and consequently in the groundwater. The most saturation indices of arsenic were for FeAsO4:2H2O and Ca3 (AsO4)2:4H2O compounds, showing that change of saturation indices for these two compounds is similar and increasing from recharge to discharge area. Based on factor analysis method, three main effective factors were distinguished on hydrochemistry of the study area. In the first factor, chlorine, sodium, potassium, arsenic, copper, iron and electrical conductivity are effective elements, which have geogenic origin. Consequently, the origin of arsenic can be geogenicthatis related to geological factors, rocks and sediments that come from alteration of geological formations. Therefore, dissolution of minerals from the Miocene deposits such as marl, shale, sandstone and red conglomerate and the Pliocene conglomerate, and interbedded marl and sandstone are the effective sources of arsenic in the aquifer.

Mineralogical and liberation studies are the most important parameters used in the selection of separation. An investigation was carried out to identify the various types of minerals present in fluorite ore and to determine the suitability of the methods for its preconcentration and final concentration. The sample has been evaluated and characterized by ore microscopy, x-ray diffraction, chemical analysis and also approximate mineralogy based on chemical analysis and Microscopic studies and also the texture characteristics such as grain size, Situation of infor locked particle and their arrangement in the ore body were also investigated. According to surveys conducted this ore contains of fluorite (40.52%), calcite (24%), quartz (20%), smitsonite (8%), galena (2%), clay minerals (3%), barite (1%) and goethite (0.6%). Carbonate phases is two parts sparry calcite, micrite to microsparate piece has been observed. Quartz, in the form of microcrystalline with limonite and goethite oxide of stained has been observed. The liberation degrees of crushed ore in different size fractions was estimated by the Counting method of showed that for fluorite (1000m), Calcite (100m) and quartz (90m) of fluorite in size 100 mesh (150m) with quartz (36%) and calcite (23%) were determined. The size fraction of -600, +425, can be assessed for gravity concentration as a preconcentration process and for the size fraction -150,+75 mm for flotation.

Noa Anticline is located in west side of Kermanshah Province and with considering extension of limestone formations in the area, and on the other hand existing faults and tectonical joints and also climatic conditions this area involves an evolution karst. This study explores of karstic evolution process and zonation of mentioned evolution accompany with recognizing the impact of different factor on the process. Data gathered from different sources such as topographic, geological, soil, land use, areal, satellite maps accompany with using statistic data of ministry of Energy and the organization of meteortology. This study have been selected nine environmental factors some as a independen parameter and karst features geomorphology as a dependen parameter. Then with intensive field works, we recognized the closed holes as the most evolutionary ones of karst features of this area , concerning characteristics of this landforms we allocated a given weight to each parameter .finally using GIS software, we prepared overlap maps and in a final manner using Entropy model, adaptation of factors and definitive modification have been performed. The results of this study shows that this area embraces four category of Karsts include lack of karst evolution, moderate evolution, high evolution and very high evolution categories. Regarding nine factors, five factors such as distance from fault, slope, slope aspect, temperature and rainfall recognized as the most effective ones and other factors such as soil factor, land use, contour lines and lithology as with no effect on area’s karst is recognized. The model precisity applying on the closed holes shows that there are 92 % closed holes in the two categories (high evolution and very high evolution) and have indicated the favourite effectiveness of using Antropy model on karst evolution zonation.

Aquifer vulnerability assessment to define critical zones of pollution risk is an important method for groundwater resource management. By applying the DRASTIC model in this study, groundwater vulnerability in the Maragheh-Bonab Plain aquifer was evaluated. The DRASTIC model uses seven environmental parameters (Depth to water, net Recharge, Aquifer media, Soil media, Topography, Impact of vadose zone, and hydraulic Conductivity) as seven layer in GIS media and finally a groundwater vulnerability map was created by overlaying the available hydrogeological data and categorized to low, moderate, and high risk. The DRASTIC index value was evaluated 81 to 116 for the study area. The vulnerability map created by DRASTIC is compared to nitrate data and the results indicate a relative correlation between the nitrate level and vulnerability index. In order to improve the model, four artificial intelligence (AI) models are adopted by optimizing the weights of the DRASTIC parameters. The four AI models are the Sugeno fuzzy logic (SFL), the Mamdani fuzzy logic (MFL), the artificial neural network (ANN), and the neurofuzzy (NF). For this purpose, the AI model input (the DRASTIC parameters), output (the vulnerability index), and nitrate concentration data was divided into two categories for training and test steps. The output of model in training step was corrected by related nitrate concentration, and after model training, the output of model in test step was verified by nitrate concentration. The results show that the four AI models are applicable to improve the correlation between nitrate level and vulnerability index using DRASTIC model for groundwater vulnerability assessment. The NF model by taking advantage of FL and ANN has the best results that high nitrate level at observation well location has high vulnerable index and was selected as a final model. According to the final model, the western areas of the aquifer are classified as high pollution risk. In conclusion, the AI approach proved to be an effective way to improve the DRASTIC model and provides a confident estimate of pollution risk for the study area.

The Tabriz plain with an area of more than 700 km2 is extended from the eastern limit of Tabriz city to the salt flats of Urmia Lake. There are two types of aquifers in this plain with different quality of groundwater. The unconfined aquifer, which is extended all over the plain, in recharge areas near the plain margins has good quality water but in the central part of the plain along the Aji Chay river as well as in the west margin of the Plain is saline. The multi-layer confined aquifers, which lie down in central and western parts of the Plain bearing more or less good quality groundwater. The arsenic concentration of these aquifers is also different; the water samples analyzed from the chemical point of view especially with respect to concentration of arsenic show two different groups of groundwater. The aim of this study is considering of arsenic spatial distribution and factors controlling high arsenic concentration in the aquifers. For this purpose 16 water samples, with evenly distributed in the Plain, were collected from the aquifers, two water samples for each well, one for analyzing major ions and the other for trace elements. They were analyzed in hydrology lab at the Tabriz University. The arsenic concentration in unconfined aquifer and in recharge areas of the plain boundary is low and in confined and deep wells is high. Arsenic concentration compared on the basis of their dependency on hydrogeological conditions, nitrate and phosphate concentrations and pH and the results interpreted by factor analysis and hydro geochemical methods. Attendance of nitrate and phosphate by positive factor and arsenic by negative factor can show the reduction conditions in groundwater system, which caused the arsenic mobilization. In spite of high arsenic concentrations in the water samples, the saturation index of arsenic minerals is very low and under saturation. The arsenic existing in groundwater resources of the area originate from the geological formations and its concentrations depend highly on the hydrogeological and environmental reduction conditions, residence time of water in underground layers and depth of the sampling wells.