عبدالحمید انصاری

The Chahargonbad batholite is located  close to Sirjan and southeast of Urumieh-Dokhtar magmatic zone. The batholite's composition is acidic to intermediate that is intruded into the Eocene volcanic rocks. Although the main volume of these rocks consisted of granodiorite and monzogranite, this mass contains numerous mafic microgranular enclaves with a combination of diorite and monzodiorite. Also, microgranular dykes have cut the mafic mass.  Existence of field evidence such as mafic microgranular enclaves with spherical to oval shapes, bell and rod shaped mafic microgranular enclaves, the presence of synplutonic mafic dykes, as well as textural disequilibrium evidences indicate the absence of plagioclase with oscillatory zoning and repeated analytical levels, and Osley quartz in the presence of enclaves. As they grow, they are minerals and evidence for magmatic mixing. Enclaves show higher values than the host rock in most of the basic elements, such as Al2O3, CaO, MgO, Fe2O3, TiO2, P2O5. The elements (REE), host granite rocks and associated enclaves show relatively differentiated REE patterns with sloping LREE patterns and flat MREE and HREE patterns. Based on the tectonomagmatic environment determination diagrams, all samples from the Chahargonbad (studied area) are located in the arc island setting due to subduction and show the characteristic of active continental margin setting.

In recent years, exploration methods based on studies of alterations due to hydrocarbon leakags from reservoir to the surface have been considered. Since these leaks occur as vertical chemnies upon the oil traps, these seeps have a relative adaptation to the position of hydrocarbon reservoirs. The purpose of this study was to process and interpret the geological, remote sensing, surface geochemical exploration data of Moghan sedimentary basin and then match the results of these data with possible hydrocarbon rich areas. In remote sensing studies, band ratio methods, RGB color composition and principal component analysis were used to identify ferrous iron, carbonate replacement by gypsum and clay minerals alterations. Also, surface magnetic anomalies were identified by applying analytical signal analysis, first derivative and continues highpass filter on ground magnetic data. Adaptation of concentration of positive geochemical anomalies first to the anticline layer and then to the combined faults and anticline layer showed that alteration of carbonate minerals and illite were the most significant altered zone observed upon the anticlines, and Ferrous iron and the surface magnetic anomalies are the least of them. Also, the concentration of positive geochemical anomalies on the anticline is higher than the area without anticline and if the faults are used, this concentration will almost double. It proves the possible leakage of hydrocarbons from the reservoirs to the surface and the creation of geochemical anomalies above them. This finding can help to locate the approximate location of underground reservoirs and significantly reduce the cost of drilling operations.

The expansion of industries in the world, the limitation of resources and the increasing consumption of water have led researchers to pay more attention to wastewater treatment than in the past. Wastewater treatment is done in order to stabilize the produced organic matter, reuse water and solid materials resulting from wastewater treatment, and also to be able to discharge the waste water into the environment and protect the environment.

This research has been investigated with the method of biological treatment information modeling using fuzzy logic. One of the cost-effective methods for purifying the sanitary wastewater of the refinery is modeling using the fuzzy logic method. Fuzzy inference systems are a popular computing framework based on the concept of fuzzy sets, if-then rules, and fuzzy reasoning. This category of systems has a successful application in the fields of automatic control, data classification, decision analysis, expert systems, time series prediction, robotics and pattern recognition. In this research, MATLAB R2012 software has been used for fuzzy logic modeling by Mamdani method. Information obtained from the tables in the article "H.A. Hegazi. 2013".

By examining all the diagrams and models, we found that the modeling done is reliable and can be used to obtain the results of other experiments without conducting experiments. Also, the best operating conditions can be called rice husk adsorbent concentrations of 50, 60, 60, 60, 60, for the removal of Fe, Pb, Cd, Cu and Ni metals. For the ash absorbent, the absorbent concentrations of 60, 60, 60, 50, and 60, respectively, were called optimal absorbent concentrations for metals. Also, among the two absorbents, rice husk is a better absorbent. The accuracy of the model was reached around 95% and proved the reliability of the model. It can also be concluded that ash and rice husk worked very well as natural absorbents and the removal efficiency was up to 90%.

The Persian Gulf basin is one of the most important regions in terms of hydrocarbon resources in the world. The Kish gas field is located in the eastern part of the Persian Gulf.  The purpose of this paper is to assess the hydrocarbon generation potential and to model the burial and thermal history of source rocks in this gas field using Rock-Eval pyrolysis, vitrinite reflection, and a 1D model.

Methodology and Approaches:

In this study, 58 rock samples were selected from layers with high natural gamma ray in Pabdeh, Gurpi, Ilam, Lafan, Sarvak, Kazhdumi, Dariyan, Gadvan, Fahliyan, Surmeh, Neyriz, Dashtak, Dalan and Faraghan Formations for Rock Eval pyrolysis and vitrinite reflection. In addition, one-dimensional modeling of burial and thermal history was performed using PetroMod software (2011-Schlumberger) on well B of the Kish field.

The TOC and S1+S2 values vary from 0.16 to 1.59%, and from 0.08 to 4.16 mg HC/g Rock, respectively. Most of the samples have low hydrocarbon potential, only a limited number from Gurpi and Pabdeh show fair hydrocarbon generation potential. The samples with fair potential have kerogen type III and II/III with the low level of maturity. The one-dimensional modeling was performed on Pabdeh, Gurpi and Sarchahan source rocks. The thermal model was calibrated with corrected down-hole temperatures and vitrinite reflections. According to the model, Pabdeh and Gurpi are immature, while the Sarchahan is currently in the gas window. It has reached the oil and gas window since 160 and 120 million years ago, and produced 95% of its potential so far.

Remanent magnetization is impossible to ignore in many applications of magnetic method including mineral exploration particularly iron ore, geomagnetism, regional investigation, and archaeological measurements. Magnetization vector inversion has made great attention in recent years since both distribution of the magnitude and direction of the magnetization have been obtained, therefore, it is easy to distinguish between different bodies especially when magnetic data are affected by remanent magnetization. In this research, the magnetization vector inversion (MVI) has presented: a 3D magnetic modelling is proposed from surface measurements to obtain magnetization distribution. The equations have solved in data-space least square to reduce computer memory requirements and speed up calculations. The algorithm has included the combination of three weights as depth weighting, distance weighting and compactness weighting in Cartesian direction. The method has been validated with a synthetic example including a dipping dyke and the results are acceptable compare with true magnetic anomaly.

Abstract The Early Cretaceous succession in the southern part of Yazd Block begins with terrestrial sediments of the Sangestan Formation. Little attention has been paid to this formation and most studies have focused on its lithostratigraphy. In this study, some geochemical studies have been performed on this formation. Twenty seven siliciclastic samples were taken from the Sangestan Formation in two sections of Bidakhvid and Alavi Mountain in order to identify the type of siliciclastic sediments, the nature of the sediments, and palaeoclimate conditions. Mineralogical studies and modal analysis showed that the siliciclastic sediments have been classified as sandstone (arkose) and siltstone. The results of factor and cluster analysis depicted that the chemical composition of siliciclastic sediments is different in the study areas. Based on multivariate analysis, siltstones that have high positive values of Zr, V, U, Sc, Sr, REE, MgO, Fe2O3, TiO2, and CaO elements are related to cement, while sandstones showed high positive values for K2O, Na2O, SiO2, Al2O3 elements. The results showed that siltstone sediments have more calcite and iron cement than the sandstone samples. By studying the variations of these elements versus the profile of the Sangestan Formation, it was observed that the elements related to rock cement are concentrated in siltstones due to the increasing depth of the sedimentary basin or more extension related to rift event, and the entrance of new elements into the basin. Also, the results of weathering indices depicted that both rocks have been formed in the same climate conditions which is consistent with the palaeogeography of Yazd Block during the Early Cretaceous.Keywords: Sangestan Formation, Yazd Block, Geochemistry, multivariate analysis, sedimentary environment, weathering index  IntroductionThe Sangestan and Taft formations dating back to the Early Cretaceous were deposited in many locations of Yazd Block which is located in the western part of the Central–East Iranian Microcontinent.In general, most studies have focused on the Taft Formation because it hosts lead and zinc deposits such as Mahdiabad, Farahabad, Mansourabad, etc. (Mojtahedzadeh 2002; Maghfouri and Hosseinzadeh 2018; Maghfouri et al. 2019; Maghfouri et al. 2020). On the other hand, a few studies have been performed on the Sangestan Formation focusing on its stratigraphy and paleontology. Until now, the geochemistry of Sangestan sediments and their sedimentary environment have not been paid attention to.The use of major, trace, and rare earth elements of siliciclastic sediments is very common in sedimentary geochemistry studies used by researchers to identify various purposes, including the tectonic setting, palaeoweathering conditions of the source area, and the nature of the source rock (Shadan and Hosseini-Barzi 2013; Wang et al. 2013; Nowrouzi et al. 2014; Salehi et al. 2014; Zaid et al. 2015; Moallemi et al. 2017; Okon et al. 2017; Periasamy and Venkateshwarlu 2017; Somasekhar et al. 2018; Abubakar et al. 2019; Etesampour et al. 2019; Sci et al. 2019; Xu et al. 2019).Multivariate statistical methods have been utilized to determine the relationship between several elements and the nature of sediments; something impossible by univariate statistical analysis. Despite the advantage of multivariate statistical methods, they have not been paid considered in siliciclastic geochemistry and they have been used only in a few studies.The main purpose of this study is to evaluate the composition and petrography of siliciclastic rocks of the Sangestan Formation, the relationship between the composition of the sediments and the deepening of the sedimentary basin, the relation between the nature of the sediments and the major and trace elements by multivariate analysis, and the climate conditions in Yazd Block during the Early Cretaceous. Material & MethodsAfter field observation, sampling was performed from the Sangestan Formation at the Bidakhavid and Alavi Mountain sections. Seventeen samples (nine siltstone and eight sandstone samples) from Alavi Mountain and 10 samples (three siltstone and seven sandstone samples) were collected from Bidakhavid.Sixteen thin sections from siliciclastic samples were studied petrographically by the Olympus model polarizing microscope.  The point counting of more than 500 points per thin section was performed on twelve sandstone samples by the Gazzi-Dickinson method.Twenty-seven samples of siliciclastic rocks of the Sangestan Formation were selected for geochemical objectives. The preparation steps of the samples which include the cutting of the samples in order to obtain an un-weathered surface, crushing, and grinding to achieve the particle sizes under 200 mesh were performed at Yazd University. Then, the representative samples were analyzed by Zarazma Mineral Studies Company (Iranian company). To determine the major oxide elements, the samples were fused by lithium metaborate and dissolved in dilute nitric acid and, finally, determined by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). An ICP-OES 735 instrument in Australia was used to analyze the samples. Moreover, the rare earth elements (REE) and other trace elements were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The instrument used was an ICP-MS Agilent series HP 4500 in the United States.SPSS and GCDkit software were used to carry out multivariate statistical studies and to plot ternary diagrams, respectively. In addition, Rockwork 14 software was used to draw the stratigraphic column. Discussion of Results & ConclusionsThe preliminary study of thin sections showed that the siliciclastic samples of the Sangestan Formation include sandstone and siltstone in the two studied sections. Sandstone samples are often medium-grained, with a small percentage of coarse-grained, moderately rounded and immature. Modal analysis was performed on sandstone samples for more detailed studies. The main constituents are quartz grains (56% and rock fragments ( less than 1%), as well as feldspar (25%).Siltstone samples are similarly composed of quartz, feldspar, and rock fragments. They have about 52% quartz, most of which is monocrystalline, and only less than 1% is polycrystalline quartz. The amount of feldspar is less than sandstone samples and they constitute about 16% of the rock volume. Similar to the sandstone samples, a few rock fragments were observed in siltstone samples. Furthermore, on the basis of the classification of Folk (1980), sandstone samples of the Sangestan Formation showed arkosic composition.  This result was validated by geochemical data confirmed by the geochemical classification of Herron (1988).In factor analysis, the positive and large factor loadings demonstrate a significant correlation between the variable and corresponding factor in the matrix. The results of factor analysis identified two first factors which discriminated the elements associated with the main constituents of siliciclastic sediments and those  related to the cement of siliciclastic sediments.For example, factor 1 showed positive factor loadings with Zr, V, U, Sc, Sr, REE MgO, Fe2O3, TiO2, CaO and negative factor loading with Cr, Na2O, SiO2, and Al2O3.  This factor depicted that the cement of rocks was formed from carbonate, iron oxide, and so on whereas the main constituents of siliciclastic samples were formed from elements such as Na2O, SiO2, and Al2O3. Furthermore, the results of the hierarchical cluster analysis shown in the dendrogram confirmed those of factor analysis.In order to evaluate the changes of these groups of elements, they were plotted along the sedimentary log. The results showed that the elements which are associated with the framework constituents of siliciclastic samples are more in sandstone rocks than siltstone rocks. Conversely, the elements related to the cement of siliciclastic sediments are more in siltstones than sandstone rocks.  Thus, it can be interpreted that the time of siltstone deposition was probably accompanied by an increase in the depth of the basin and the presence of more cement in the basin. Finally, the results of (A-CN-K) Al2O3-(CaO*+Na2O)-K2O ternary diagram and diagram which was proposed by Suttner and Dutta (1986) depicted that these sediments have been deposited in arid to semi-arid climatic conditions.

One of the methods of harvesting oil reservoirs is the injection of nanoparticles. Nanoparticles increase oil recovery from reservoirs by changing wettability, reducing surface tension, reducing oil viscosity. Metallic nanoparticles (ceramic nanoparticles) have the highest application in increasing the absorption of reservoirs. In this research, changes in the contact levels of oil, water, and stone in the presence and absence of metal oxide nanoparticles have been investigated. The change in the rock's wettability has been analyzed in various concentrations of nanoparticles in the aqueous phase and the governing mechanism for changing the rock solidity in two metal oxide nanoparticles is presented. 4 nanoparticles used in this study are TiO2, NiO, Co3O4, Al2O3 The specimens were then measured by the DSA and the angles were measured and it was observed that the maximum gradient of the graph is related to nickel oxide followed by cobalt oxide and then titanium oxide and the lowest slope to aluminum oxide. In this respect, from this point of view, Nano particles are considered as NiO> Co3O4> TiO2> Al2O3, respectively. So the first suggestion is to select the most suitable nanoparticles of metal oxide, NiO, and for the second position Co3O4, the third and fourth choices are TiO and Al2O3, respectively.

In water resources management, correct identification of bedrock characteristics, such as type, depth and structure is useful and various geophysical methods are used for this purpose. In geophysical and subsurface investigations, solving inverse problems using physics of the problem in partial differential equation (PDE) system is very important. Inverse modeling is one of the useful solutions which creates a logical model between observed and measured values. The limitations and ambiguity of individual techniques can be significantly reduced by adopting joint inversion schemes. Using inversion approaches which combine two or more geophysical methods, allows substantial improvements in modeling processes. The joint inversion of different electromagnetic and resistivity data sets in hydrogeology, structural geology and mining has been used in some studies but the gravity method is less used in hydrogeological investigations. One example of using gravity method in previous studies is an algorithm for joint inversion of gravity and resistivity data, where the interfaces corresponding to changes in the bulk density were interpreted as interfaces of porosity and water content changes, i.e. interfaces of electrical resistivity changes.    In this paper, we present a framework for joint inversion of gravity and geoelectric data solving under-determined inverse problems. It can be used in a wide range of physical systems governed by PDEs. The integrated approach is based on the connection between density and resistivity of a sedimentary sequence through the porosity. Also, we present a general adjoint state formulation which may be used in this framework. It increases the calculation speed of sensitivity matrices in a variety of commonly encountered under-determined problems. There are two steps in this research. First, 2D joint inversion of gravity and geoelectric data is run and validated in COMSOL multi-physics software using one synthetic model and synthetic data in a forward modeling process. Afterwards, using real gravity and geoelectric data surveyed along a cross-section in part of the Qotrum plain in the SE Yazd, the lateral structure of bedrock is estimated. Because Qotrum basin is already well surveyed, it offers opportunities for evaluation of accuracy and reliability in joint inversion approaches. Fifty-one gravity stations and eleven vertical electrical soundings were carried out across the central part of this basin to apply the proposed joint inversion. The results indicated that gravity-geoelectric joint inversion is more accurate than the individual interpretation of each of these methods and significantly improves the solution by decreasing the ambiguity of models. Furthermore, this method, while high in computational speed, can be used in modeling of a wide range of geophysical, hydrogeological and physical systems governed by the partial differential equation laws.

The paper introduces the 3D Cross-Correlation for modeling of total magnetic intensity and its vertical gradient which is the fast way to model data, detect anomalies and estimate their depths and locations. In this approach first, we divide the subsurface space into a 3D regular grid, after computing the correlation value for each node of the grid, these values are plotted. It is noted that the results fall in the range [-1, +1] that represents the mass excess or mass deficit of magnetization (or susceptibility) relative to the magnetization (or susceptibility) of the host volume. This approach is applied to 2 synthetic models. The results show acceptable accuracy of this method in depth estimation and expansion of buried masses. After this method is verified and validated, it will be applied to the Shavvaz mine's total magnetic intensity (TMI) data of Yazd and its vertical gradient, and the results will be discussed.

There are two major approaches for 3D inversion of magnetic data: (i) direct inversion of the density contrast using a linear or nonlinear algorithm, and (ii) modeling of the source distribution in a purely probabilistic sense, in which the results are equivalent physical parameters between +1 and -1. Direct inversion has an inherent problem called Non-uniqueness of solutions and requires a lot of computer memory because of the number of model parameters and data.
In this paper, we introduce and evaluate the 3D Cross-Correlation (CC) method for 3D modeling of magnetic data (or its vertical gradient). This method was applied to 2 different synthetic models and its strengths in modeling of total magnetic field anomaly and vertical magnetic gradient data are discussed and finally, the method was applied to the Shavvaz mine's TMI data and its vertical gradient.
 

Methodology and Approaches:

The 3D cross-correlation approach is a method for modeling the magnetic data (or its vertical gradient) without any external constraints and any linearization.

The results of synthetic examples showed the high accuracy of the CC method in determining the shape and depth of the buried mass. This method is simple and easy to run and there is no need for prior information. In the end, this method was applied to the Shavvaz mine's TMI data and its vertical gradient. These results showed that orebody continues deeper than 40m (estimated from the previous modelling).

The population growth, the development of cities, industry, agriculture, and improper use of resources especially non-renewable resources have led human beings to face the danger of running out of resources. In some cases, in addition to the above, irreversible environmental and geological hazards have occurred due to the overdrawn of resources. Over extraction of groundwater resources is one of the problems that, in addition to human exposure to the risk of water scarcity, also induces risks due to this over-harvesting. The phenomenon of land-subsidence is called subsidence for natural and human reasons. One of the reasons for this phenomenon is human activities, including the overextraction of groundwater resources and the water table drop. Subsidence itself results in some problems such as deep cracks in the ground, well pipes growth and collapse of buildings. One of the common subsidence damages in many plains of Iran is the creation of sinkholes. Sinkholes are deep pits that are mainly involved in the development of karst dissolution and subsequently many risks to urban and environmental areas. The areas affected by the subsidence phenomenon have been identified using the Synthetic Aperture Radar Interferometry (InSAR) method. The interferometry technique uses electromagnetic wave interference to extract information. Radar interferometry uses the phase difference of radar images with a high spatial resolution seeking to produce a digital elevation model of the region and estimate the amount of deformation and displacement of the earthchr('39')s crust. In the radar interferometry technique, complex radar images containing the phase values ​​and amplitude of the wave returning from the complication to the sensor are combined and an image called an interferogram is produced. An interferogram is an image that results from the subtraction of two images taken at two different times that are aligned on each other. An interferogram contains information of the phase difference between the two images, which indicates the difference in distance between the terrain features and the sensor in the two captured images. By having the phase difference value, various parameters such as the amount of ground displacement can be obtained. Persistent Scatterer Interferometry (PSI) time series analysis method uses stable scattering pixels (pixels that have scattering patterns with a constant scattering pattern over time) to extract information and overcome the limitations of radar interferometry. In the present research, an attempt has been made to monitor the subsidence of Abarkooh using the Synthetic Aperture Radar Interferometry method.Abarkooh region is located in Yazd province which is an agricultural region in recent decades and the extraction of groundwater resources has been increased in it. Abarkooh city has two urban points, Abarkooh and Mehrdasht. Excess extraction of groundwater caused numerous subsidence and sinkholes, subsequently. Hydrological studies have determined the rate of groundwater level drop equal to 0.6 m/yr. In this paper, by using 55 Sentinel-1A satellite images in the period of 2017 to 2019, 54 interferograms have been used to process time series analysis based on persistent scatterer after deducting the participatory phases from the interferogram phase. Finally, the average subsidence rate map for the Abarkooh region is estimated. According to the analysis, the maximum subsidence rate of the Abarkooh region is 3 to 4 cm /yr and the maximum subsidence rate of the Mehrdasht region is 6 to 7 cm/yr. Accordingly, by considering the location of the subsidence area in the agricultural lands of the studied region and the decrease of the water table level in that region, one may conclude that the subsidence has happened due to the over-extraction of groundwater resources. In order to investigate the impact of subsidence on the environment, the soil salinity map has been calculated. In general, the salinity of the region is increasing as a factor impacting the degradation of surface soils and desertification. Well pipes growth, sanding of water wells, and reduction of well’s discharge, all are some examples of the consequences of subsidence in the destruction of wells. Other consequences of subsidence in this area include turning the plain into a desert, damaging aquifers, changing the topography of the land, and environmental pollution. Due to the un-uniform distribution of the subsidence areas in ​​the region, the damages to roads, railways, urban and industrial buildings, and energy transmission lines have been predicted. One of the most important subsidence consequences in this area is the creation of deep holes and longitudinal cracks along with the subsidence area. To evaluate the results of the interferometry technique, GNSS station data have been used. Since the data related to this area are available from 2011 until now, it is possible to obtain an accurate evaluation of the InSAR results. The results show that the displacement rate is 1 cm based on the permanent station data (GNSS) and the interferometry measurement results show a displacement rate of 0.7 cm. These values indicate the accuracy of the results of radar interferometry.

Radar interferometry technique is an efficient tool to study changes in the Earth's crust. The method is based on the phase difference between two image pairs at different time intervals. In this research, subsidence of Abarkuh plain, Yazd province investigated. The subsidence is actually the lowering of the Earth's surface due to the natural and human activities. Excessive extraction of underground resources, especially water, is a main cause of subsidence in many plains in Iran. Hydrological studies in this area show a groundwater level drop of 0.6 meters per year. According to the geological studies, karst developments and dispersive clay soils are two causes of subsidence. By the radar interferometry technique over a period of 2003 to 2005 using 12 Envisat satellite images, the average subsidence rate in the region was estimated. In Abarkouh, maximum subsidence rate is 2 to 3 cm/year and in Mehrdasht area 5 cm/year. Accurate alignment studies have been used for the accuracy of the calculations between 1985 and 2001, which are in agreement with the results obtained by radar interferometry. The reasons for this discrepancy are the inconsistency between two available data and the radar interferometry error.

The gravity method measures the vertical component of the acceleration at the Earth’s surface. The earth’s gravity field is affected by the density of different rocks and structures. Therefore, this method can be used in mineral exploration or studying the subsurface cavities and structures such as bedrocks, channels, and dikes.Inverse modeling is useful in understanding the physical phenomena on earth and applies to various fields of earth science, including geophysical exploration, groundwater hydrology, and seismology. In forward modeling, we assume that all physical parameters are known, and various models can be simulated through physical laws and scientific relationships. Despite the direct measuring of unknown parameters in inverse modeling, we would like to know their spatial distribution.Recognition of bedrock depth and geometry in aquifers, is the first stage of groundwater investigation. Geophysical methods play a significant role in the investigation of aquifers because they are the only way to detect deep subsurface structures at much lower costs than the most direct methods like drilling. Due to the complexity of alluvial sediments in terms of type and grading as well as difference between type and depth of bedrock, geophysical modeling approach and achieving the expected result are very important. Undetermined inverse problems that the unknown parameters are more than the measured values, can be solved using problem physics in the partial differential equation (PDE) system. Inverse modeling is one of the useful solutions to create a logical model with relationships between observed and measured values.

In this research, a template is presented to solve undetermined inverse problems using COMSOL multiphysics’ optimization that can be used in modelling a wide range of physical systems governed by the partial differential equation laws. The results indicated that this method, while high in computational speed, can accurately discriminate between low-density contrast regions and the background. Flexible and fast processing is an advantage of this method.

In this paper, gravity forward modeling will be implemented by solving Poisson’s equations with the appropriate boundary conditions, and then a methodology is presented for solving gravity inversion problems using COMSOL Multiphysics. COMSOL multiphysics does not include a gravity calculation module. However, since gravity and electrostatics are both governed by Poisson’s equation, a gravity model can be created in the electrostatics module by changing the electrical permittivity value.In inverse problems, if the number of unknown parameters is more than that of measurement values, the inverse problem is called underdetermined. The objective function for an underground inverse problem is the sum of a fitness and penalty term: The first term is equivalent to a weighted data-fitting criterion, and the second term measures the smoothness of the field relative to the given variogram. The penalty term distinguishes between solutions with comparable fitness values in problems where the number of parameters, exceeds the number of measurement values.We will apply this technique to a 2D synthetic gravity model using the AC/DC module of COMSOL. In the gravity field, a common inverse problem is estimating the density of subsurface structure givenmeasurements from the vertical component of gravitational acceleration. First of all, 2D inversion of gravity data has been run and validated in COMSOL software using some synthetic models and synthetic data in a forward modeling process. Afterwards, using real gravity data surveyed along two cross-sections in a part of Qotrum plain, the bedrock lateral structure was estimated and inverted density values cross-correlated with existing well logs.

Undetermined inverse problems in which the unknown parameters are more than the measured values can be solved using problem physics in the partial differential equation (PDE) system. This research, presented a template to solve undetermined inverse problems of 2D gravity data using COMSOL multiphysics’ optimization applying in 2D or 3D modeling of a wide range of different underdetermined inverse geophysical problems. Despite the most inversion codes designed for a particular application, this method applies to a broad range of physical systems governed by PDEs.The main benefit of COMSOL for solving inverse problems is that, once a user is comfortable with the software, it can solve a wide range of physical problems. Additionally, COMSOL’s ‘‘Multiphysics’’ capabilities allow coupling intrinsically to several physical equations.

During wet mineral processes in mines, a large amount of wastewater is produced and stored in tailing dams. In Miduk copper mine, Shahr-e-Babak, Kerman, Iran, there are tailing dams and wastewater dams as a result of mineral processing. The wastewater dam normally is constructed in order to separate and to reserve the water content of tailings, and finally, to reuse it for mineral processing. In this study, we have used the geophysical methods (electrical resistivity tomography (ERT) and self-potential (SP)) to investigate the seepage from the wastewater dam of the Miduk copper mine. The ERT surveys show a low electrical resistivity zone (less than 20 Ωm). It can be as a result of a clayey alteration zone or fractured zone. In addition, SP measurements show a positive anomaly in the same area due to the seepage from the dam walls. It can be due to an electrokinetic source origin. The observed natural source in the same zone, confirmed the geological, hydrogeological and geophysical interpretations. These results show the ability of ERT and SP methods to investigate the seepage zones related to wastewater dam walls.

Mining like other industrial activities can affect the environment negatively. Tailing dams have long been associated with mining activities and have formed a major negative impact. Excessive seepage in the foundation of the dam threatens the integrity of the structure. Geophysics has been used intensively in environmental problems, in particular in the study of mine tailings problems. In fact, geophysical surveys especially electrical resistivity tomography (ERT) and self-potential (SP) methods constitute a comprehensive methodology for assessment of anomalous seepage conditions by detecting, mapping and monitoring the zones.

The field survey to detect the seepage in Miduk wastewater dam was composed of a geophysical survey and a hydrogeological study. The hydrological study was performed in order to identify water table, surface water and groundwater quality, and to understand the relation between water collected in dam and water resources. Such a study is very common in environmental geochemical investigations. The ERT survey was carried out along 2 survey lines, called P1 and P2, using the dipole–dipole array with an electrode spacing of 20 m in the survey line P1 that has a total length of 400 m, however, the survey along the survey line P2 has been carried out using an electrode spacing of 5 m. The survey line P2 is 100 m long. A maximum n value of 11 was used for both P1 and P2 ERT profiles. All data were acquired by a WDDS-2 resistivity meter using multi-electrodes cable. The SP survey along SP1 and SP2 survey lines was carried out on the northeast abutment of the dam. The SP measurements were taken using two non-polarizing electrodes (Cu-CuSO4), one electrode was located at the base station as a stationary electrode and the other moving along the desired line at pre-fixed stations. The base-station was chosen at a point convenient for operation but away from the expected anomaly. Electrodes polarization was controlled between measurements using two constant points in the site. In order to identify the water table, in a part of the hydrological study, water depth in 6 observation wells, located downstream of the water retention dam, was measured. In the second part of the hydrological study, hydrochemical investigation was carried out by taking 17 water samples collected from 15 stations. The hydrogeochemical characteristics of water were obtained through physicochemical analysis of the water samples.

The ERT survey shows a low electrical resistivity zone (less than 20 Ωm). It can be the result of a clayey alteration zone or fractured zone. The SP measurements show a positive anomaly in the same area due to the seepage from the dam wall. According to the hydrochemical study, the water type of this area is bicarbonate-chlorate while the water type of one borehole and the dam water sample are both sulfate-chlorate. The obtained information from the survey area confirms the geological, the hydrogeological and the geophysical interpretations

Nowadays, the quality of water resource and recognition of the effective factors in it is one of the most important issues in the world regarding consideration of water shortage. The interaction between water resources and porous and environmental media plays the important role to control of groundwater quality. Moreover, identification of this interaction can be helpful for optimal water management. Because of its agricultural and industrial importance, the groundwater quality assessment of these interaction affects the Galehdar plain which is located in the south of Fars province, Iran, is necessary. In this study, geological and anthropogenic factors affecting the groundwater quality of Galedar plain were investigated using analyses and interpretation of pumping-well quality data of 20 water well samples in March 2011. Piper charts, composition diagrams, statistical analyses, factor analysis, saturation indices, and maps of the hydrogeochemical parameters were used to in determination of the salinity sources and effective processes affecting the quality water of the aquifer. Water type changes from carbonate and sulfate to sodium-magnesium chloride in the direction of groundwater flow which is being consistence with Chebotarev ionic evolution and higher residence time. Based on piper diagram, groundwater of Galehdar is Cl-Na and SO4-Ca type. The composition diagrams show a clear linear trend between Na and Cl and also between Ca and SO4. This implied the arrival of waters originating from halite and gypsiferous formations and salty soils. Statistical and factor analyses demonstrate three effective groundwater quality-control factors. The first factor which is the most effective groundwater quality control-factor, explaining 51.9 percent variance of data and shows halite dissolution. Assessment of saturation indices demonstrates that total trend of hydrogeochemical processes of Galehdar plain is halite and gypsum dissolution and sedimentation of calcite and dolomite. Surface waters recharging the aquifer where passed through the unsaturated aquifer media is the most probable of deterioration of water quality and chloride ion concentration increasing. The results show that the main groundwater quality degradation reasons are waters passes over salty soils, agricultural wastewaters, salt-water rivers, dissolution of gypsum and halite, and runoff originating from Gachsaran and Aghajari formations which is the most effective factor in the Calendar groundwater quality deterioration.

Cu-Mo porphyry deposit of Aliabad Damak is located at 35 km southwest of Taft in Yazd province, Iran. A detailed exploration of this deposit has been carried out. The indications of mineralization on the surface can be seen as veins and contaminations of Malachite - Azurite with some Pyrite and Chalcopyrite, and rarely Chalcocite and Covellite. The mineralization took place as stockwork texture and scattered distribution. The hydrothermal solutions due to Aliabad's semi-deep intrusive body, in addition to copper mineralization, have caused severe alteration of granite and Cretaceous sedimentary-volcanic units. While the phyllic alteration has the largest extent, outcrop of potassic alteration has not been seen in the study area yet. Argillic and propylitic alteration zones are also seen in and around the phyllic alteration. According to the drilling wells in the area, potassic and propylitic alterations can be observed inside and around the phyllic alteration in depths. Magnetic and IP/RS (with rectangular and pole-dipole array) surveys have been performed in the studied area. In this research, we tried to adapt the different alteration zones with geophysical anomalies. In studied area phyllic alteration zones have weak magnetic anomaly, propylitic alteration zones are associated with mild magnetic anomaly and argillic zones have not any sign of magnetic anomaly. Relation between different alterations and chargeability and resistivity anomalies was investigated in this study. Phyllic alteration zones show low resistivity and high chargeability, potassic alteration show high resistivity and low chargeability and propylitic alteration zones represent moderate resistivity and chargeability.