مقالات رزومه دکتر علیرضا عرب امیری

This paper presents the results of inverse modeling of induced polarization (IP) and resistivity data, acquired from Oshvand polymetal deposit area, using the Li-Oldenburg and Smoothness constrained algorithms. Oshvand deposit is located in northeast of Nahavand City in-Hamedan Province of Iran. To demonstrate the effectiveness of these algorithms, we have applied them on both synthetic and real data. In the synthetic case, good agreement is seen between the synthetic model and the estimated model, which is extracted from the inversion procedure. The inversion results of the real data example show good agreement between the results and geological evidences. It is also shown that twodimensional (2D) inverse modeling of IP and resistivity data provide invaluable information about the subsurface resistivity and chargeability distributions.

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.

Basic approach for investigation of Khazar fault, due to covered areas by quaternary deposits and absence of the fault outcrop in some of areas in the region, is to use the subsurface exploration methods, and especially, high resolution geophysical methods. In this study, we calculated the subsurface geometric parameters of Khazar fault, geological model, and especially, the Khazar fault borders in Khalilshahr region by comparison of GPR and resistivity profiles, and combining the results with geological results, and then, we made forward and inverse modeling of the resistivity and GPR data.

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..

Independent component analysis (ICA) is a relatively new multivariable statistical method originally devised for the blind source separation (BSS) problem, where there is no information on how to mix primary sources (mixed signals) and only the necessary condition is independence of the primary signals. Hence, ICA can be used in mineral potential modeling where several independent mineralization processes result in observed variables such as geophysical and geochemical information, and we do not know how the geophysical and geochemical effects of different mineralization processes are mixed together. In this study, we tried to introduce the ICA method as a knowledge-driven method of mineral potential modeling. To this end, an area of 4800 square kilometers in south of Neyshabur, northeast of Iran, was investigated to map the mineral potential of podiform chromite deposits. In this regard, geochemical stream sediment sampling data, ophiolitic facies map, structural pattern of fractures and serpentinite alteration location in the region were used for this study. Finally, the results of mineral potential modeling by the ICA method were compared with the results of univariate and multivariate geochemical studies and were also validated by using locations of the known mineral prospects in the region and receiver operating characteristic (ROC) method. As a result, the area under the ROC curve was marked by 0.967, indicating the outstanding performance of the ICA modeling.

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.

In this study, processing and interpretation methods in remote sensing such as visual and spectral analysis have been performed on the ASTER (advanced spaceborne thermal emission and reflection radiometer) data from Zarshuran gold area, and as a result, the alteration zones in the area have been identified. Then, the results of two-dimensional and three-dimensional modeling of Induced Polarization (IP) and resistivity data, using geological information, alteration and mineralization from the core drilling have been interpreted. Eventually, optimal locations for exploratory drilling have been proposed.

Development of advanced tools in remote sensing and geophysical exploration during recent decades indicates the necessity and importance of these tools in industry. In this paper, ASTER sensor imagery and geoelectrical data have been used in order to determine alteration zones, analyze mineralization system and identify the hidden mineralization in Zarshuran gold mine located in the north of the city of Takab, northwest of Iran. For this purpose, a variety of imageprocessing methods are used. IP and resistivity methods have an important role for exploration of metallic ore deposits. To achieve good results from these methods as well as minimizing the noise in the study area, it is necessary to select appropriate electrode array type for carrying out IP and resistivity surveys. For this purpose, IP and resistivity field operations over 17 parallel survey lines using the pole-dipole array have been made to identify the location of goldmineralization in the area.

In order to identify alteration zones, image processing methods such as BR (band ratio), PCA (principal component analysis), LS-Fit (linear band prediction) and SAM (spectral angle mapping) using ENVI software were applied on the ASTER images from the study area. After collecting IP and resistivity data in the area, two-dimensional and threedimensional smooth inverse modeling were carried out on the data using Res2dinv and Res3dinv software packages, and for better visualization, the results were demonstrated in Voxler and Rock Works software packages.

Identification of alteration zones in the study area using remote sensing and image processing methods, and interpretation of the geophysical inverse modeling results using geological and drilling information in the area have been led to the identification of gold mineralized zones or deposits in three-dimensional form. Eventually, based on the whole results, optimal locations for exploratory drilling have been proposed. An outcome of this research is that applying both the remote sensing and geophysics data can be led to improve the accuracy of the results. As the obtained geophysical anomalies at the end of some survey lines have been open, therefore, it is suggested to continue geophysical operations at the end of these survey lines. For better display of gold mineralization, it is also recommended to carry out geophysical operations on a number of survey lines perpendicular to main parallel survey lines. As the acquired considerable IP values in the study area can be due to metallic minerals as well clay minerals, therefore, it is recommended that some samples to be taken from drillings or excavations in the area, and then, to be analyzed by x-ray diffraction (XRD) equipment to determine the amount and type of possible metallic or clay minerals in the samples.

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.