فهرست مطالب alireza arab amiri

Drones, also referred as Unmanned Aircraft Systems (UAS), Unmanned Aerial Vehicles (UAV) or Remotely Piloted Aircraft (RPA), are aircraft without pilot on board. Currently the drones are used for geological and topographic mapping, coastal control, landslide inspections, etc., and are capable to integrate geophysical sensors like magnetic, electromagnetic, infrared, radar, natural gamma ray sensors and etc. UAS technology have several advantage over conventional airborne geophysics like resolution, accurancy, cost, etc. We are witnessing the birth of a new branch of aviation, which could be profitably applied to geophysics measurements.In the modern-day advent of new technologies and methodologies in geophysics has become more important than ever before in acquiring better data from the Earth’s subsurface. This advent has yielded a somewhat predicted fusion in the way geophysical data is acquired, by combining the power of Unmanned Aerial Vehicles (UAVs) and smaller, more hardware-integrated sensing equipment. Safety and cost considerations very play in the cause and effect of this culture shift in the realm of geophysics, whereas drones are more capable of flying closer to the ground, have greater vertical gradients, require less power for flight, and most evidently, the nonnessecity of human collateral. Ultimately, drones should be, and to an extent is becoming, at least in geophysics, the way of the future.

In recent decades, various methods have been developed for mineral exploration. Geophysical methods are one example, which have seen significant development in recent years and have become a common approach in the field of mining exploration, particularly in Iran. The objective of this study is to investigate the exploration area of Chahshen in terms of the potential for copper mineralization using geophysical methods and to identify promising areas for drilling. During field visits, it was observed that the main mineralization on the surface is of the oxide type, specifically malachite and azurite. Therefore, to explore the potential expansion of sulphide mineralization at greater depths, induced polarization and resistivity methods were employed. For this purpose, a rectangular array with a data collection distance of 20 meters and a line distance of 40 meters was used to determine the general trends in the region. Subsequently, six profiles were designed and measured using dipole-dipole and pole-dipole arrangements at 20-meter intervals. Through modeling of the studied sections, two-dimensional models depicting chargeability and resistivity were generated. The two-dimensional models indicated that the eastern regions exhibited more anomalies. However, due to the relatively weak nature of these anomalies, the possibility of developing a sulphide zone at shallow depths was detected. To validate the obtained results, drilling points were proposed. Profile 1 suggested a drilling point at station -10 with a depth of 45 meters, while profile 2 proposed a drilling point at station -10 with the same depth.

In this work, we simulate the frequency-domain helicopter-borne electromagnetic (HEM) data over the two-dimensional (2D) and three-dimensional (3D) earth models. In order to achieve this aim, the vector Helmholtz equation is used to avoid the convergence problems in Maxwell’s equations, and the corresponding fields are divided into primary and secondary components. We use the finite difference method on a staggered grid to discretize the equations, which can be performed in two ways including the conventional and improved finite difference methods. The former is very complex in terms of programming, which causes errors. Furthermore, it requires different programming loops over each point of the grid, which increases the program’s running time. The latter is the improved finite difference method (IFDM), in which pre-made derivative matrices can be used. These pre-made derivative matrices can be incorporated into the derivative equations and convert them directly from the derivative form to the matrix form. After having the matrix form system of linear equations, Ax = b is solved by the quasi-minimal residual (QMR). IFDM does not have the complexities of the conventional method, and requires much less execution time to form a stiffness or coefficient matrix. Moreover, its programing process is simple. Our code uses parallel computing, which gives us the ability to calculate the fields for all transmitter positions at the same time, and because we use sparse matrices thorough the code memory space, requires to store the files is less than 100 MB compared with normal matrices that require more than 15 GB space in the same grid size. We implement IFDM to simulate the earth’s responses. In order to validate, we compare our results with various models including the 3D and 2D models, and anisotropic conductivity. The results show a good fit in comparison with the FDM solution of Newman and the appropriate fit integral equations solution of Avdeev that is because of the different solution methods.

This study investigates the efficiency of different geophysical methods for detecting contaminated zones as well as hidden pipes. There are a number of geophysical techniques that can be useful and beneficial for achieving these purposes. Ground penetrating radar (GPR) and electrical resistivity methods are the most useful approaches for identifying polluted areas and buried features, causing us to utilize such methods in the area. Although GPR and electrical resistivity methods are solely effective for mapping subsurface targets, the integration of these methods might provide us valuable information and valid outcomes. In this paper, electrical resistivity and GPR surveys are conducted and acquired data are modelled to investigate the pollution leakage in the ground. To achieve this aim, a polyethylene pipe with inlet and outlet valves is considered as a tank buried underground in the geophysical test site of Shahrood University of Technology. In the first step of the study, the electrical properties of the empty pipe were measured and modelled using electrical resistivity and GPR methods. In the next step, the pipe was filled by the cupric sulfate solution and electrical measurements were performed again. In addition, the electrical properties were investigated by means of electrical resistivity and GPR methods in another area, sitting on alluvial soil, after and before injecting the cupric sulfate solution. It is worth mentioning that the measurements were performed after drying the surface which was humid due to the injection of cupric sulfate to avoid false conductivity on the ground. The designed profiles include four lines on a buried reservoir and five profiles on alluvial soil. However, the 2D modeling results and interpretation of the acquired data along with two (on the buried target) and three (on alluvial soil) survey lines are just presented in this paper. After collecting and interpreting the electrical resistivity and GPR data in the study area, the results are in the form of two-dimensional models of electrical resistivity and GPR cross sections, which have been obtained by use of RES2DINV and Prism2 softwares, respectively. The obtained results revealed that the electrical resistivity method enjoys a relatively good performance in detailed detection. It is also shown that the GPR method is not able to work properly in alluvial soils with high clay and it suffers from the unsuitability of the transmitter antenna with a frequency of 150 MHz and the destructive effect of moisture on the performance. Regarding the obtained outcomes and using electrical resistivity data, ground details such as polyethylene reservoir, loose and porous soil parts and separation of different areas according to the relative humidity in them have been revealed.

Geophysical methods are suitable methods for prospecting and exploration of mineral deposits. Using two or more exploratory methods together and combining them with other information such as geological studies can increase the probability of discovering and reaching promising areas. According to the evidence of metallic and sulfide mineralization in the study area (the exploratory area of Pirmardan), the use of magnetic, induced polarization (IP) and electrical resistivity (Res) for prospecting and exploration of the mineralization in the area is of great importance. The position and the spatial relationship between mineralization and lineaments have long been considered by geologists. Airborne magnetic data and geological information are used to diagnose and distinguish the general trends of structures, lineaments, and large faults using tilt filter on magnetic data. By processing and interpretation of the airborne magnetic data of the region, the existing structures in the region have been investigated. Moreover, considering the available geological information in the region, the induced polarization and the electrical resistivity data have been acquired using the rectangle arrangement to detect the subsurface anomalies and also using the dipole-dipole arrangement along two survey lines to obtain the lateral and depth extension of the anomalies. Airborne magnetic data processing has been performed using Oasis Montaj software, and also, processing and modeling of induced polarization and electrical resistivity data have been carried out using RES2DINV and ZONDRES2D software packages. The final results obtained from the interpretation of airborne magnetic, induced polarization and electrical resistivity data confirm the relationship between lineaments and the probability of hidden copper reserves in the study area. These results have led to propose five spots for exploration drilling.

Lack of the existence of known mineral prospects in the preliminary stages of mineral exploration is the main problem of data-driven mineral potential modeling methods. On the other hand, applying the expert’s knowledge and judgment in different stages of mineral potential modeling, is the main difficulty of knowledge-driven mineral potential modeling methods. In addition, other difficulties in these methods can be mentioned such as determination of important variables, weighting to various classes of maps or information layers, and so on. Hence, the accuracy of the results of the knowledge-driven modeling methods is highly dependent on the amount of knowledge and experience of the expert. In this study, the principal component analysis (PCA) has been introduced as a knowledge-driven method with the least reliance on the expert’s knowledge for mineral potential modeling. In this method, the expert’s knowledge is only used in the interpretation of the results obtained from the modeling, and is not considered in the first stages of mineral potential modeling and definition of the conceptual model. In the introduced method, the interpretation of the results is conducted based on the positive and negative coefficients of variables in the eigenvalues table. Using these coefficients, it is determined that each principal component (PC) is associated with what type of mineralization. An advantage of this introduced method is to identify various types of mineralization in the area of interest using just one modeling effort. In order to evaluate the efficiency of this method, a region including two geological maps of Kadkan and Shamkan in the south of Neyshabur, northeast of Iran was selected. Two mineralization types including podiform chromite and epithermal gold-antimony mineralization types have been identified using the proposed method that presents more precise results than those of conventional univariate and multivariate geochemical studies.

Increasing demands of raw materials and energy resources has led to a fast growth in the geophysical studies. Due to the properties of minerals and geological conditions, there are various geophysical methods. Among these methods, magnetic method is capable of exploring the magnetic mineralization of rocks with relatively high or low magnetic properties. In this method, the magnetic field variations of the ground are measured. Sonajeel is located 17 kilometers from Harris, East Azarbaijan Province. The main stone units in this area are from the old to the new: volcanic and volcanoclastic rocks, Sonajeel porphyry stock, Incheh granitoid stock, and Okuzdaghi volcanic rocks. In this study, the magnetic method is used as an indirect method for identification of copper ore deposits. Based on the magnetic method, information can be obtained about the gradient, depth, shape, and extension of the source of anomalies. There are several examples for using this method (especially the airborne magnetic method) to explore the copper deposits. Including the copper project in the Cadia region of Australia, as well as the use of magnetism to explore the mineralization of copper and gold in the polymetal exploration area of Bashmaq Hashtrood. For the aim of identification of copper mineralization in the study area, the magnetic data along 19 survey lines were carried out. The length of each line was considered to be1000 meters and magnetic measurements were made at magnetic stations having distance intervals of 20 meters. The distance between the successive survey lines was 50 meters, except the distance between survey lines 19 and 18 that were located 30 meters from each other. The total survey area was about 1 km2. After applying diurnal correction on the magnetic data, the processing of the data was made by applying various filters such as reduction to the pole (RTP) to remove the effect of the inclination angle and to locate the subsurface position of the anomaly that is assumed to be symmetrically placed on the creator mass, upward continuation filter to study the process of mineralization in depth, and also, vertical derivatives and analytical signal processing methods were used to estimate the anomalous boundaries. Three-dimensional (3D) modeling of the magnetic data was also carried out using the Mag3d software. The results indicated that the mineralization process was extended in the north and north-east to the south-east of the study area. Upward continuation filtering was applied to the data at altitudes of 20, 40, 80 meters. The maps resulting from this filtering represented the root of the subsurface anomaly in the southeastern of the region. As a result of comparison of the various magnetic images with the 3D model, obtained from modeling the magnetic data using the Mag3d software, we found out that the copper mineralization in the study area is scattered but covers a large range of the area. Moreover, according to the results of 3D modeling of the data, the magnetite susceptibility in north and northeast of the study area is more than that in south and southeast of the area. The contrast of the magnetic susceptibility in north of the study area from the depth of 100 m to 270 was high, however, in the east and southeastern parts of the study area, from the depth of more than 100 meters, there was a high magnitude of magnetic susceptibility. Hence, it can be concluded that in the northern parts of the study area, potassic alteration was closer to the ground surface. It should be mentioned that the potassic alteration is a good place for copper and magnetite mineralization as the copper and magnetite mineralization is located in the center or middle of the potassic alteration. By comparing and interpreting the magnetic results and assessing these results with the geological data or information from the study area, the probability of occurrence of the magnetite mineral and, consequently, the copper mineralization or deposits in the Sonajeel area is highly indicated.

Chahar-Gonbad region of Kerman province is geologically located in the southern part of central Iran zone, dominantly in Uromieh-Dokhtar volcanic belt. In this region, many high potential prospects, specially Cu-Au mineralization, have been detected during large scale exploration and reconnaissance phases. In this paper, remote sensing and field geophysics were used for alteration mapping on the surface and ore body delineation on the subsurface, respectively. To this end, we used an ASTER satellite image and different maps were generated by spectral technics such as false color composites and spectral ratios. Results showed argillic (and phillic) alteration in Bab-Zangoeie area is surrounded by propylitic alteration, which could be a promising evidence for Cu mineralization. Integrating these results with previous exploration studies led to selecting target area selection for ground study and field geophysics. We used both induced polarization (IP) and resistivity (RS) methods as two powerful geoelectrical methods by a pole-dipole array along four profiles. After preprocessing analysis, forward and inverse models were constructed in 2D section and 3D overlay model of joint IP/RS anomalies were constructed. Based on the obtained results, the deposit in depth where we proposed drilling targets. Further drilling operation have proved the mineralization in our proposed targets..

The Sharifabad-Bardeskan copper mineralization is located in northeast of Bardeskan and south section of Sabzevar Zone. Mineralization occurs as vein in the pyroxene andesite, tuff, sandstone and conglomerate of Eocene age, which bearing local sericite - carbonate and silicic alterations and regional propylitic alteration. Mineralization occurs as open space filling, disseminated, veinlets and consists of chalcocite pyrite, chalcopyrite, malachite, azurite with calcite and quartz as gangue minerals. Fluid inclusion studies in calcite show the evidence of mixing trend during the ore formation occurred at a wide range of temperature 200to 437 °C and varying salinity between 0.1 to 9.2 wt.% NaCl equivalent. The stable isotope composition of δ34S fall in a range of -23 to -24.3‰ could be considered as biogenetic sulfur from bacterial sulfate reduction. The δ13C values of calcite vary between -3.4 to -24.5‰ suggest a major contribution of marine carbonates associated igneous carbonates. Copper and sulfide rich hydrothermal fluid has flowed upward through the local faults and permeable interbeds within the Eocene volcanic sequence and formed the mineralized veins. Based on the mineralization, alteration, fluid inclusion and stable isotopes, Sharifabad mineralization is similar to those manto type deposits in Chile.

Gravity inversion is a classical tool in applied geophysics. Inversion of basement relief of sedimentary basins is an important application among the nonlinear techniques. Classically, local deterministic optimization techniques have been employed to solve the non-linear gravity inverse problem. Swarm intelligence algorithms, such as ant colony algorithm or particle swarm optimizers, are promising alternatives to classical inversion methods. In this study, imperialist competitive algorithm (ICA), was designed and utilized for two-dimensional (2D) gravity inversion of basement relief in sedimentary basins. Reliability of this technique was tasted by modeling of gravity data acquired from a synthetic model, and then, the synthetic model parameters were obtained from this modeling approach with acceptable accuracy. Moreover, the results of utilizing this approach on noisy data showed that this approach was robust to the presence of noise in the data. For the case of real data, this approach was applied on a real gravity profile in Atacama Desert (north Chile) and the results were confirmed with previously published works related to this area. Generally, compared to techniques already proposed for 2D nonlinear gravity inversion, the ICA technique, proposed here, appears as a powerful tool for estimating the basement relief of sedimentary basins.

The thickness of sediments in sedimentary basins with hydrocarbon sources potential is one of the primary factors in determining the thermal maturation of these basins. This research has been done with the aim of two-dimensional modeling of the basement geometry of a sedimentary basin using the inversion of the gravimetric data. A common way for this problem consists in discretizing the basin using polygons (or other geometries), and iteratively solving the nonlinear inverse problem by local optimization. This procedure provides a solution that is highly dependent on the initial model and on the prior information that are used. Moreover, due to non-linearity of this inverse problem, local optimization methods would fail whenever there is no reliable initial model. Global optimization methods are promising alternative to classical inversion methods because the quality of their solutions does not depend on the initial model; also, they do not use the derivatives of the objective function. This research investigates the design and implementation of the CSO (competitive swarm optimization) algorithm as a novel algorithm in global optimization, for two-dimensional non-linear modeling of gravity data as a substitute for the local response methods such as Marquardt-Levenberg and Gauss-Newton. In first steps, designing and implementing the proposed algorithm were verified on synthetic model data. For evaluating the validation of this developed algorithm, it was tasted by both synthetic example include free noise data and data with presence of white Gaussian noise. Also, the results of application of this applying on noisy data show that this approach is robust to the presence of noise in data. Finally, reliability of proposed method to the inversion of a real gravity data was confirmed by applying it on a real gravity profile in the Moghan sedimentary basin. Results of this modeling agree well with previously published works on this Area.

Introduction:

 The Sharifabad copper deposit is situated in the Sabzevar zone and Eastern Iran Cenozoic volcanic rocks. The area is covered by a detailed exploration program, which includes preparation of the geological map of the area at 1:5,000 scale, and drilling several hundred meters of trenches. This study focuses on the copper bearing veins system and determination of subsurface mineralization by conducting geological and geophysical operations. For carrying out geophysical operations, 5 survey lines have been designed, and then, surveyed in the area. In this paper, the results of modeling and interpretation of geophysical data acquired along two survey lines DD1 and DD2 have been presented. The geophysical data include IP-Res measurements at 460 points along these two survey lines using dipole-dipole array with the electrode intervals of 20 meters that have been conducted by Omid Geological Engineering and Geo-Science Company.

 Methodology and Approaches:

 The raw field geophysical data along the two survey lines DD1 and DD2 have been modeled using two-dimensional (2D) smooth Inversion by RES2DINV and ZONDRES2D software packages. The 2D model sections are displayed in threedimensional (3D) form using RockWorks software. The inverse modeling results and geological studies lead to the recognition of the copper mineralization zones and local faults in Sharifabad area.

 Results and Conclusions:

 The results of geophysics studies in Sharifabad area show high resistivity and IP values in two depth levels 0 to 25 m and 32-49 m. On the basis of the geological and geophysical studies, eight locations for drilling exploration boreholes are proposed, and as a result, three boreholes have been drilled up to a depth ranging 33-40 m. Drilling studies confirm copper mineralization with high copper values in the depth of about 39m. These studies have also led to the identification of four local faults near the mineralization zones.

Inversion of basement relief of sedimentary basins is an important application among the non-linear modeling techniques. Particularly in sedimentary basins with hydrocarbon source potential, the thickness of sediments is one of the primary factors in determining the thermal maturation of these basins. Gravity methods have been vastly used to estimate the base of sedimentary basins. The aim of this research is two-dimensional modeling of the basement geometry of a sedimentary basin using the inversion of the gravimetry data. A common way to approach this problem is discretizing the basin using polygons (or other geometries), and solving the non-linear inverse problem by local optimization iteratively. This procedure provides a solution which highly depends on the initial model and the used prior information. Besides, due to the non-linearity of this inverse problem, local optimization methods will fail whenever there is no reliable initial model. The global optimization method is a promising alternative to classical inversion methods because the quality of their solutions does not depend on the initial model. Also, they do not use the derivatives of the objective function.Ant colony algorithm (ACO) is one of the kinds of important swarm intelligence algorithms which have been successfully applied in many fields such as inversion of geophysical data. This research, in two separate stages, investigates the design and implementation of the ACO as a powerful tool for two-dimensional non-linear modeling of gravity data. ACO can be a substitution for the local response methods such as Marquardt-Levenberg and Gauss-Newton. To apply this algorithm in the problem under consideration, it was validated with the data obtained from a synthetic model and then, reverse modeling of the real data was performed. For evaluating the validation of this developed algorithm, it was tested by the synthetic model. Data from the synthetic models were modeled by using the developed algorithm, and acceptable results were obtained. By using this approach, the topography of the basement in the synthetic model was obtained with acceptable accuracy. In this study, the effect of ACO algorithm on different values of probable noises was investigated. The results indicate that this algorithm is suitably stable against the Gaussian white noise with relatively high amplitudes. In modeling for high noise percentage, the root mean square error of the data calculated with the original data didn't exceed 1.64 mGal and that obtained with the original model at most was 131.4 m. The results of modeling show acceptable agreement with the original model even in the case of data contaminated with 10% Gaussian white noise.The reliability of the proposed method to the inversion of a real gravity data was confirmed by applying it on a real gravity profile in the Moghan sedimentary basin. The results of this modeling are compatible with previously published works in this area.

The host rock in Chumalu area includes the Eocene volcanic rocks and the Oligocene monzonite intrusive mass that have undergone propylitic-carbonate, silica, and silica-argillic hydrothermal alterations. The hydrothermal activities resulting from the injection of intrusive mass have produced two types of mineralization in the region: the first mineralization type is a silica-shear zone having N70E trend, and the second type is in the form of a bunch of veins with an approximate trend of northwest to southeast, located in the north of the first mineralization type. The mineralization is of the form of vein, veinlet, massive, scattered and replaced, and follows the trend of the faults. The ore contains lead, zinc and fluorine, along with copper, gold and silver, which are formed of chalcopyrite, pyrite, galena, sphalerite, cerussite, calcite and fluorite minerals. Based on the results of the geological studies conducted in this study, the mineralization characteristics of Chumalu area are of the type of lead and zinc hydrothermal deposits. Induced polarization (IP) and resistivity data acquisition were first designed and carried out using rectangular array to determine the anomalous zones, and then, using dipole- dipole array to determine the lateral and depth limits of these anomalies. Then, modeling of IP and resistivity data was done using smooth inversion method. For better representation of the results, all two-dimensional (2D) sections were combined and as a result, a three-dimensional (3D) model was presented. Consequently, an anomaly with an approximate east-west orientation in the south of the area has been extended on the silica-shear zone, and some anomalies with an approximate north-south orientation in the north of the area, in relation to the fractures of the basaltic deposits, which can be linked with metallic mineralization in the area. Anomalous areas with high chargeability and medium to low resistivity values have been determined. High chargeability values for some anomalies in the north of the area are probably due to the presence of scattered pyrites in depth. Finally, 6 points were proposed for drilling.

Application of IP and resistivity geophysical methods and their integration with geological studies is of great importance in the exploration of sulfide metal deposits. The Chumalu area is located 70 km northwest of Zanjan in the Tarom-Hashtjin metallogenic zone, which has possible potential for metal reserves and mineral resources. The purpose of this research is to collect and process raw IP and resistivity data using the smooth inverse modeling, interpretation of the results based on geological studies and finally determining the anomalous limits, depth and thickness of probable mineral masses in the area and at the end, suitable locations for drilling are suggested.

This research is based on field and laboratory studies. In order to conduct geological studies, alteration, mineralization and determination of the genesis of the mineralization, 8 thin sections and 9 polished sections of surface and subsurface samples from the mineralization ore and host rock were prepared and studied. Moreover, field operations of IP and resistivity data acquisition were first made in the form of 4 networks using rectangular array in order to determine the anomalous limits with a current line of 800 meters long, electrode spacing of 20 meters, and the distance between the lines 50 meters. Then, 6 lines using dipole-dipole array were surveyed in order to explore the lateral and depth limits of these anomalies with electrode spacing of 20 meters. Then, modeling of IP and resistivity data was made by 2D smooth inversion method using RES2DINV and ZondRes2D software packages. Furthermore, all 2D sections were combined using RockWorks software and a 3D model was presented. Ultimately, possible mineralization limits were identified and suitable sites for drilling were proposed.

Based on the geological studies, lead and zinc mineralization in olivine basalt volcanic host rock and part of the monzonitic intrusive mass in Chumalu area occurs during hydrothermal processes and in the form of veins along fault structures. Chumalu mineralization is of hydrothermal lead and zinc type. Based on geophysical and geological studies, anomalies have been introduced that have high chargeability and medium to low resistivity, as probable mineralization. Finally, 6 locations were proposed for drilling.

Considering the geomechanical characteristics of the subsurface facies in well location can play an important role in reducing the sand production from reservoirs. The main step in the geomechanical characterization in the reservoirs is to create an accurate geomechanical zoning. Due to the intrinsic spatial variability and also the high heterogeneity of the facies making such geomechanical zoning is accompanied with high uncertainty without having a reliable structural model of the reservoir facies. In recent decades, multiple-point simulations (MPS) have been considered not only as an efficient gadget to estimate the geomechanical properties in the reservoirs but also as a tool for the modeling of the heterogeneous facies. The importance of generating an accurate model of the subsurface facies has led to the development of various algorithms to improve accuracy and computational efficiency. In this paper, a new algorithm is proposed for numerical modeling of heterogeneous facies in oil reservoirs. The proposed algorithm is based on Discrete Wavelet Transform (DWT) and the Cross Correlation (CC) function. For this reason, the proposed algorithm is called CCWSIM. The accuracy and computational efficiency of the proposed algorithm are compared with another well-known MPS algorithm, called MS-CCSIM, in a two-dimensional synthetic model of the reservoir. The results of the comparison show high accuracy of the proposed algorithm (CCWSIM) in the reproduction of heterogeneous reservoir facies. In addition, the proposed algorithm is more efficient than MS-CCSIM algorithm.

Airborne magnetic and electromagnetic methods are among the most efficient geophysical techniques for the detection of buried anomalies. There are several methods that can be used to estimate the depths of the buried anomalies. In general, modeling methods can be used not only to estimate the depths of the buried anomalies, but also, to determine physical and other geometric factors of the anomalies such as lateral extension, thickness, dip and so on. In this research, magnetic lineaments have been determined using the airborne magnetic data, acquired in a part of Bazman area with an area of 24 square kilometers located in about 125 kilometers northwest of the city of Iranshahr. By applying filters such as reduction to the pole, first horizontal derivatives, analytical signal, tilt angle and upward continuation filters. For processing and interpretation of the airborne magnetic data, the Oasis Montaj module of Geosoft software package has been used. The processing, display and interpretation of the airborne electromagnetic data have been made Conductivity Depth Imaging (CDI) using EM Flow and Profile Analyst software packages of Encom Company. Furthermore, the depths of the lineaments in this area have been estimated using Euler deconvolution method. Then, the obtained results have been compared with the results of airborne electromagnetic investigations for the frequencies of 900, 7200 and 56000 Hz using horizontal and vertical coplanar coils. Also, the obtained findings from the airborne magnetic and electromagnetic methods have been validated by the geological information of the area. The airborne magnetic and electromagnetic data of the area have been acquired using airborne magnetometer and DIGHEM5 electromagnetic instruments, respectively. The airborne magnetic and electromagnetic surveys over the study area have been made by Geological Survey of Iran (GSI) in 2005. As a result of this study, 22 magnetic lineaments in the area have been identified in which 4 lineaments coincide on the main faults of the area as the validation results indicate. In this regard, the main faults can be observed on the obtained magnetic maps in which different filters have been applied, however, the tilt angle magnetic map indicates the main faults of the area more clearly. This implies the better performance of the tilt angle filter over the other filters in displaying magnetic lineaments. Totally, 22 magnetic lineaments have been determined on the magnetic maps. By the results of this study, we can conclude that the main faults of the area have an approximate trend of northeast-southwest. Some of these faults, which have been determined from the airborne magnetic investigations of the area, cannot be determined from geological studies of the area as they have been overlain by the Quaternary sediments. The different performances of these main faults on the lithological variations and tectonic activities of the area have been clearly evident by the result of this study. The main faults of the area have also played a vital role on the formation of folds and fractures, and occurrence of weak earthquakes. The approximate depths of the lineaments, which have been estimated by applying the Euler deconvolution method on the acquired magnetic data are around 100-200 meters.

The Asmanou deposit is located in 85 km east of Shahrood, in the Sabzevar zone and Toroud- Abbas Abad district. The host rocks of mineralization are pyroxene andesite, basalt, basaltic trachyandesite and trachybasalt which display shoshonitic affinity and characteristic of continental arc setting. The country rocks in the Asmanou variably altered and two type of alterations, regional and local, could be distinguished; zeolite- carbonate regional alteration is widespread in the area and local alteration associated to the mineralization are chloritic and hematitic. Mineralization occurs as vein and stratiform and the common textures are disseminated, vein- veinlet, stock work and open space filling. Chalcosite is the main ore mineral accompanied by subordinate magnetite, hematite, bornite, chalcopyrite, pyrite and secondary minerals including covelite, malachite, coprite and goethite. Nonmetallic minerals are calcite, quartz, chlorite and zeolite. Fluid inclusion studies from the calcite and quartz from the main hypogene stage yielded the homogenization temperature between 79 to 350 °C for calcite, and 160 to 250 °C for quartz. Salinities for calcite is between 2.3 to 22 wt% NaCl eq. and for quartz between 6.1 to11.3 wt% NaCl eq. The results of this studies show the mixing and boiling are two important factors in the mineralization. Geophysical studies using resistivity (Rs) and induction polarization (IP) show the high values of IP-Rs in 5 to 40 m depth. Mineralogy, ore texture and structure, and fluid inclusion characteristics in the Asmanou deposit are similar to those manto type copper deposits.

Summary Temporal changes in the earth magnetic field occur in the frequency band of millihertz to a few hertz. Amplitudes of variations above 0.1 Hz are usually much smaller than 1 nT, changes of 50-100 nT over periods of a few hours are not uncommon. Total-field aeromagnetic surveys typically require days or weeks to complete. An airborne magnetometer measures variations in the magnetic field caused by flying over magnetic geological structures and by temporal variations in the earth magnetic field. The most common method of estimating and removing the effects of time variations is called leveling. The standard procedure of leveling the data requires additional tie-lines flown perpendicularly to the original lines. In this study, a leveling approach is used without the need for tie-lines. The method, used in this paper, utilizes nine-point Hanning filter to creat a smooth representation of the regional magnetic field. The leveling errors are the difference between the flight-line raw magnetic data and the derived regional magnetic field. The magnitude of the error is minimized through least square method with a firstdegree function, and the correction involves only a diurnal correction (DC) shift. The technique is applied to the aeromagnetic data set acquired in Moalleman area, Semnan, Iran. The results show that the stripy effects are removed and the unleveled data is improved.
Introduction Aeromagnetic data have to be leveled for removing temporal variation effects from the observed anomalies. The leveling of aeromagnetic data is an important step in interpretation procedure. We can assume that the total magnetic intensity is invariant within the altitude variations of the aircraft. As such, measured data at intersection points, should record same values. Differences at cross points (where tie-lines intersect the flight lines) are attributed to leveling errors. The flight-lines are then leveled using leveling errors. Due to strong gradients in the anomaly magnetic field and the low flight altitude at modern surveys, errors at intersection points are commonly larger than the potential accuracy of modern high-resolution aeromagnetic surveys (e.g., Methodology and Approaches Leveling aeromagnetic data can be carried out using two methods. In the first method, leveling the data is made using tie-line. Leveling the data in the second method is carried out without the need to tie-lines. Corrections, which have to be performed before leveling, include diurnal and heading corrections. If required, an international geomagnetic reference field (IGRF) correction has to be applied. By using a nine-point Hanning (3*3 convolution) filter, any highfrequency noise is removed, and the regional magnetic field data, which are free of leveling errors, are derived. The differences between unleveled magnetic data and derived regional magnetic field data should be minimal. Therefore, we can write:Mr=(mr1, mr2, … , mrN)T
Md=(md1, md2, … , mdN)T
X= (x1, x2, … , xN)
∆d = md - mr
|∆d-f(x)|2 = min
where Mr is the derived regional magnetic field data, Md is unleveled magnetic line data and f(x) is the error function. The function f(x) can be defined as first-degree polynomial and is determined in a least-square sense along each line in the survey.
Results and Conclusions leveling is necessary before processing and interpretation of aeromagnetic data. The standard procedure of leveling the data is performed using tie lines. The acquisition of aeromagnetic data over the tie lines are expensive. In this paper, the aeromagnetic data have been leveled using a new approach without the need for tie lines. It has also been shown that this approach can save about 10% of the operational cost. This scheme has the major advantages such as leveling is done computationally, not manually, and also, leveling large data set is made in less than an hour. This technique has been tested on a real aeromagnetic data set acquired from an area in north of Moalleman, Semnan, Iran. In the analysis of the two applied leveling techniques, we see that the least square method improves the quality of the unleveled raw data better than in the tie line technique.

Generally, the measured secondary field data is inverted into resistivity using two principal models; the homogeneous half-space model and the layered half-space model. While the homogeneous half-space inversion uses single frequency data, the inversion is done individually for each of the frequencies used, the multi-layer 1D inversion is able to take the data of all frequencies available into account. The resulting parameter of the half-space inversion is the apparent resistivity which is the inverse of the apparent conductivity. It's possible that using the fast method to calculate the apparent resistivity, if the distance between the HEM sensor and the top of the half-space is known. Unfortunately, the dependency of the secondary field on the half-space resistivity is highly non-linear. Thus, the inversion is not straightforward and the apparent resistivities have to be derived by the use of look-up tables, curve fitting or iterative inversion procedures (Fraser, 1978; Siemon, 1997; Siemon, 2001).The usual technique for inversion of airborne electromagnetic data frequency domain (HEM) data is a 1D single site inversion, because of the 2D and 3D inversion of HEM data wants very powerful computer hardware. Some inversion method for electromagnetic data inversion suggested. Usually this method updated for ground electromagnetic methods. One of the methods employed in the inversion of airborne electromagnetic data frequency domain (HEM), Levenberg-Marquardt method inversion (MLI) is looking for smoothing fitted to the data in the inversion algorithm; this inversion method based on least squares criteria, seeking a modelby minimizing the residuals of an objective function. Marquardt’s inversion only pursuits the largest fitting of simulation data to original measurements, and has the characteristics of simple algorithm and fast calculation. In this procedure usually HEM data smoothed and then used in the inversion procedure, but any variation in data change results. For stability of inversion procedure, it is suggested that stitched-together 1-D models along the profile that each sounding inverted by constrained neighbor sounding and each layer of each sounding inverted by depth constrained neighbor layers. In addition used smoothing constrained in inversion procedure instead of smoothing a data like Marquardt–Levenberg inversion.
In this paper, Starting model determined for apparent resistivity with Mundry technique and for centroied depth with Weidelt technique. To using this method, the auto inversion cod written in MATLAB software environment that inputs are real and imaginary part of data with sensor altitude and output is inverted model with misfit. In the following this algorithm tested on standard synthetic data, the model chosen for the generation of synthetic data represents a layered earth structure having an inhomogeneous top layer in order to study the influence of shallow resistivity variations on the appearance of deep horizontal conductors in one-dimensional inversion results. The inversion of synthetic data results shown this technique for inversion HEM data improved the results and is much more accurate than Marquardt–Levenberg inversion. Finally the inversion algorithm used to invert a set of real DIGHEM field data from Mirgah Naqshineh area in Saqqez of Kurdistanand interpretation of results according to geology information of area.

The helicopter-borne electromagnetic (HEM) frequency-domain exploration method is an airborne electromagnetic (AEM) technique that is widely used for vast and rough areas for resistivity imaging. The vast amount of digitized data flowing from the HEM method requires an efficient and accurate inversion algorithm. Generally, the inverse modelling of HEM data in the first step requires a precise and efficient technique provided by a forward modelling algorithm. The exact calculation of the sensitivity matrix or Jacobian is also of the utmost importance. As such, the main objective of this study is to design an efficient algorithm for the forward modelling of HEM frequency-domain data for the configuration of horizontal coplanar (HCP) coils using fast Hankel transforms (FHTs). An attempt is also made to use an analytical approach to derive the required equations for the Jacobian matrix. To achieve these goals, an elaborated algorithm for the simultaneous calculation of the forward computation and sensitivity matrix is provided. Finally, using two synthetic models, the accuracy of the calculations of the proposed algorithm is verified. A comparison indicates that the obtained results of forward modelling are highly consistent with those reported in Simon et al. (2009) for a four-layer model. Furthermore, the comparison of the results for the sensitivity matrix for a two-layer model with those obtained from software is being used by the BGR Centre in Germany, showing that the proposed algorithm enjoys a high degree of accuracy in calculating this matrix.

The need for clean groundwater resources to have sustainable development in a country is undoubted. Due to the importance and high quality of karstic waters in supplying water in Iran especially in Shahrood city, it is attempted in this research work to recognize and explore karstic waters in southwest of Tepal area, Shahrood. For this purpose, integration of the results obtained from the methods of vertical electrical sounding (VES) and resistivity profiling has been used in this research work. The VES surveys have been performed in 10 sounding points using the Schlumberger array with electrode separations of a maximum 500 meters. The resistivity profiling surveys using dipole-dipole electrode array with 75m electrode spacing and dipole steps 1 to 8 have been carried out along four lines having a length of more than four kilometers in the study area. Then, one-dimensional (1-D) modeling and interpretation of the sounding results using master curves and IX1D software, and two-dimensional (2-D) modeling and interpretation of the profiling results using Res2DINV have been made. As a result of the interpretation and integration of the results, karstic water zones in the study area have been recognized, and based on that, suitable locations for drilling to access and extract karstic groundwater have been introduced.

Potential field images obtained in potential field data measurements are suitable tools for mineral and hydrocarbons resources explorations. These images consist of different anomalies which in many cases are contaminated with noise. The horizontal location of the boundaries of potential field anomaly sources is of interest in potential field interpretation. However, the edge of potential field sources is not clear, because of the loss of resolution of the anomaly shape with respect to the shape of their sources. Edge enhancement is a technique, applied to potential field data to produce regions of constant field amplitude that are separated by sharp boundaries, as an aid to interpretation. Various methods have been introduced for anomaly edge detection, such as the analytic signal, tilt angle, total horizontal gradient and profile curvature. The tilt angle is the ratio of the first vertical derivative to the horizontal gradient. Curvature of the geophysical data is one of the most important attributes with many applications in geophysical data processing and interpretation. The profile curvature at a point shows the change in slope in maximum gradient direction. We can compute the tilt angle and profile curvature by Eq. (1) and Eq. (2), respectively

Ground penetrating radar (GPR) method as a high resolution non-destructive geophysical method is used for detection of shallow subsurface targets. This method is based on the transmission of electromagnetic waves inside the earth and recording the reflected waves from the subsurface. As the method uses high-frequency electromagnetic waves in the frequency ranges of 12.5 to 2500 MHz (called GPR waves), it can only be used for shallow subsurface investigations. Using this method, continuous images of the reflections of GPR waves from the interfaces of subsurface media with different electrical properties are obtained. Shallow cavities, due to their different electrical characteristics from the background, are among the targets which can be detected by this method. Since the depth of penetration of GPR waves in an area is controlled by the electrical conductivity and permittivity of the ground of the survey area, the depth of penetration of GPR waves, where fine-grained sediments are present, is relatively lower due to higher electrical conductivity of fine sedimentary grains compared to coarse sedimentary grains. Thus, the relative grain sizes and clay content of the subsurface sediments can be investigated by the GPR method. In general, shallow subsurface structures, having different materials and thicknesses, can be detected by the method as the structures and their host media normally have different electrical (namely, conductivity and permittivity) properties. In this research work, the GPR data acquisition has been carried out using 250 MHz shielded antenna along 5 lines in Darkhanyab area near Mojen Town, which is located at the distance of approximately 25 km northwest of Shahrood City. The purpose of this GPR survey is to detect shallow subsurface structures such as the water Qanat in the area. Due to the low distance between the GPR transmitter and receiver as well as the electrical properties, especially the conductivity of the ground, and also, to remove the unwanted low frequency signals or reflections while preserving the high frequency signals, the Dewow filter was applied before any other processing to all GPR data sets. Short time intervals between the transmitted GPR pulses and the pulses received directly from the air-ground surface, and also, the existence of reflections from the shallow subsurface targets, cause signal saturation in the receiver. For this, the Dewow filter is applied on the GPR data to correct for signal saturation or Wow in the data. Different types of gains are also among the processing methods applied on the data to reduce the attenuating effect of the GPR waves as the depth increases. To demonstrate the effects of different gains and to select the optimum gain, we applied different gains on the GPR data. To convert the trace from a wavelet with both positive and negative components (i.e. sine or cosine nature) to a mono-pulse wavelet with positive components, we used the envelope filter. This process removes the oscillatory nature of the radar wavelet and shows the data in its true resolution, making it easier to interpret. In this research, for processing the two-dimensional (2-D) GPR data or sections, Win_Ekko_Pro software was used. In addition, for three-dimensional (3-D) processing and modelling of the GPR data, EKKO-Mapper and EKKO-3D software programs were used. To display the output data from the Win_Ekko_Pro and EKKO-3D software programs, we also used T3D software. These software programs have been developed by Canadian Sensors & software Company. The results of this research work indicate that using the characteristics of GPR waves in the 2-D GPR sections; we can detect the subsurface targets such as cavities and discriminate coarse-grained sediments from fine-grained sediments, and also, determine the electrical properties of subsurface layers with high success. High resolution of the GPR data in this research have enabled us to determine the water qanat interfaces with its surroundings such as soil-concrete, concrete-air, air-water and water-concrete interfaces in the subsurface. Furthermore, the high conductive clayey soils above the water qanat canal in some places cause high attenuation of the GPR waves, and thus, highly limit the depth of penetration of the GPR waves. This phenomenon is also seen in the surrounding zone of the water qanat canal that mainly occurs due to the seepage of water to the ground. The soil bedding can also be easily observed in the obtained GPR sections. The horizontal soil layers, having thicknesses of several centimeters, have covered the surface of the ground in the survey area. A high resistive subsurface zone in the GPR sections, characterized by the ringing phenomenon, is interpreted as a cavity. In general, the relative high conductivity of the ground in the area causes to have a limited depth of penetration of the GPR waves that rarely exceeds 2 meters. The location of the water qanat in the shallow subsurface of the area was evident from the 2-D and 3-D GPR modeled sections. However, the detection of the water qanat in depths greater than 1 or 2 meters was difficult or even impossible from the GPR results due to the limited depth of penetration of the GPR waves in the area. Overall, it was possible to discriminate coarse-grained sediments from fine-grained sediments, and to some extent, to determine the amount of clay content and moisture in the subsurface from processing, modeling and interpretation of GPR data.