The main minerals in the Yiliu polymetallic ore district are mainly As, Sb, Pb, Zn, Ag, W, Sn, Nb and Ta, the deposit types and the ore-controlling factors are complex and diverse. Recently, by using 1:50000 geochemical stream sediment survey, geochemical soil survey and CSAMT method in this ore district, supergene distribution of elements were found, and many integrated anomalies were delineated. A comprehensive evaluation of all kinds of anomalies shows that the F3 fault has features of ore-passage structure and ore-storage structure, and the area sandwiched between F2 and F3 fault are favorable ore-forming place, whereas the depression parts of biotite granite which have high resistance and multiple sets of fracture intersections are most favorable places for mineralization.

The Xiangutai copper polymetallic deposit is located in the Jiujiang-Ruichang ore concentration area, Jiangxi Province. It is a porphyry-skarn-hydrothermal filling type copper polymetallic deposit found in the integrated exploration area in recent years. Analyzing systematically the ore-forming geological background, ore-controlling conditions, prospecting indicators, and soil geochemical and geophysical characteristics, this paper induces the deposit prospecting information. The prospecting region can be delineated by the ore-forming geological background and ore-controlling conditions, and the general distribution of concealed orebodies can be more effectively delineated coupled with multiple anomalies based on 1:10000 soil survey, 1:10000 high-precision magnetic survey (upward continuation to 50 m),IP detection of apparent chargeability and the apparent resistivity, and EH-4 continuous conductivity profile measurements. Therefore, it is very important to establish a comprehensive prospecting model in the search for such deposits in the study area.

Transient Electromagnetic Method (TEM) exploration was carried out in the Tianyu Cu-Ni deposit of eastern Xinjiang to sum up the geophysical characteristics of magmatic sulfide Cu-Ni deposits related to mafic and ultramafic rock bodies. In this paper, the characteristics of TEM response, time constant and resistivity for orebody, fracture and rock body are summed up from in-loop and borehole TEM data. Experiments show that the decay curves of the orebody decay slowly and the gradient of the late channels is about 1.3~1.5 at double logarithmic coordinate, with its apparent time constant being about 0.5ms. The TEM response of background decays is quicker than that of the orebody with its gradient being about 2.7 and its apparent time constant being about 0.23 ms. The apparent resistivity of the orebody from the inversion data is below 200Ω·m, while that of the background is higher than 500Ω·m. Fractures are distributed in the transition zone of high resistivity and low resistivity. The application effect of the TEM is good in the sulfide Cu-Ni deposit, and can provide some reference for exploration of the same type deposits.

In order to accelerate the prospecting work for the Yanjiao mining area in Jiangcheng City, the authors made full use of the integrated geophysical method. First, the authors delineated three exploration target areas by using high power TD IP method. Then the authors studied the ore-controlling structure in the target and its extension through AMT to find favorable metallogenic area. Drilling verification led to the discovery of three concealed Pb-Zn orebodies. 5.766 million tons of the 122 b+333 class industrial sulfur lead-zinc resources are added to the reserves of the ore deposit. The results obtained by the authors show that we can quickly identify lead-zinc anomaly body, which provides the basis for further prospecting engineering through IP method and AMT method. This is one of the effective methods to find the same type of ore deposits.

The Xiatong Mountain in Zhejiang Province is in the eastern part of the Qin-Hang metallogenic belt, where tungsten molybdenum mineralization phenomena have been found in the contact zone of the rock mass. According to the 1:5000 soil measurements in 2012, lead and zinc content is very high in carbonate formation which belongs to Banqiao Mountain strata, which are the key strata of lead and zinc deposits in the region. The results obtained show that lead and zinc anomalies in this area could be considered as the key anomalies related to mineralization. In consideration of the facts that the anomaly concentration areas of lead and zinc are distributed in the south of carbonate formation instead of having to do with the rock mass, mineralization phenomena at the surface are not obvious, and discontinuous oxidation cap could be observed, it is inferred that the lead and zinc anomalies might be caused by secondary enrichment. In order to make a further study of the genesis of the anomaly, the authors chose exploratory trench rock and soil samples to make a comparative study of lead and zinc values. It is found that the content of lead and zinc in soil is significantly higher than that in the rock. Then the authors chose three section lines to conduct a soil element content research, and the results show that the distribution of Pb, Zn and Fe, Mn has much to do with the concentration-dilution relationship. On such a basis, it is concluded that the Pb, Zn anomalies here have no mineralization significance, and they are false anomalies caused by the carbonate weathering secondary enrichment.

The soil geochemical characteristics of the Zengjiaxi copper-sliver mining area in Hunan have been systematically summarized through the geological mapping and soil geochemical survey on the scale of 1:10000 in this paper. The concentration clarke values and variation coefficients of W,As,Sb in soil are both high,which indicates that these elements were involved in mineralization. The association of main metallogenic elements consists of W, Sb, As and Au which can be used as the indicator elements for prospecting. Four soil geochemical anomaly belts were delineated based on the geological and heochemical analysis,and among them Ⅰ,Ⅲ-1 and Ⅳ anomaly belts have the better prospecting potential.

Yaoshangkeng area in eastern Yuhuashan volcanic basin lies in the northeastern part of the Qinzhou-Hangzhou metallogenic belt. The complex tectonic setting of the study area is favorable for mineralization. According to the result of mathematical analysis and single element anomalies, Cu has a close affinity with Mo, so do Pb and Zn. The copper anomaly area and molybdenum anomaly area, characterized by large size and high intensity, are distributed on both sides of the contact zones between magmatic rocks and metamorphic rocks, show good consistency with each other, and may be related to the medium-high temperature mineralized hydrothermal filling metasomatism on the lithologic interfaces. Four areas were selected as targets for further exploration, and anomaly verification for target area Ⅱ shows that the strongest anomalies usually appear around the fractured quartz veins caused by extension fractures. In order to determine the major factors (NE-trending faults or different lithological contact zones) that are responsible for element anomalies, the authors suggest the performance of relevant anomaly verification in the other three target areas.

On the basis of SinoProbe,scientific drilling ZK01 of the Luzong ore district located in the Yangtze River basin of eastern China is an integrated geophysical logging study.This study aims at establishing the physical property of lithologic section and revealing the vertical distribution law of metals in the lower crust.For the purpose of detecting the lithologic distribution of the Luzong ore district and providing the information concerning the distribution of metallic ores and evaluation of reserves,the authors chose Support Vector Machine (SVM) to established automatic lithologic identification model for all of the wells.Three methods,i.e.,Grid Search (GS),Particle Swarm Optimization (PSO) and Genetic Algorithm (GA),were applied to find the best parameters C and γ.GA was the best method becasuse it took 34 seconds to obtain the best parameters as (151.9852,9.1105),and its accuracy was up to 98.6364%.Compared with BP neural network identification results,the GA-SVM model achieved better accuracy of 86.86%.The lithologic identification and automatic zonation results are similar to the core data and artificial lithologic section,and the rationality and feasibility of GA-SVM are verified.

Uneven electric body near the ground surface interferes the target field, which is called static effect that is regarded as one of the noises of deep exploration. In order to deeply understand the static effect, the authors simulated respectively the ground surface responses of axial and asides observation methods on the conditions of taking homogeneous earth as model background and Cagniard apparent resistivity as explanation parameter. Some conclusions have been reached:(1) The effects of static characteristics of the two observation methods are consistent. (2) The interference is maximum for measuring points above the anomaly body. On the contrary, the interference is minimum for the points which stay away from the anomaly body. (3) Low resistivity abnormal body causes the contours of the interference area to become concave. The resistivity is lower. High resistivity abnormal body causes the contours of the interference area to become convex. However, changes of contours into convexity are not obvious although the resistivity of anomaly body is enlarged. Both low resistivity abnormal body and high one cause the mid-low frequency contours to become nearly erect in the interference area; (4) The static effect of low resistivity causes the standard curve to be parallel downward in mid-low frequency, but in high frequency the extent of the standard curve paralleling downward depends on low resistivity value, the lower the resistivity is, the less parallel the standard curve downward is, because of stronger electromagnetic induction for lower abnormal body which is superimposed upon the static effect. However, the static effect of high resistivity causes the standard curve parallel upward in full frequency, which is consistent with previous conclusions. The results can provide a reference for the identification and improvement of static effect correction algorithm and hence has a certain theoretical and practical value.

In gobi region of Xinjiang, annual rainfall is rare, water evaporation is strong, surface is dry, and hence it is easy to form a thin layer of dry Quaternary matter accumulation. High-power induced polarization geophysical prospecting requires a higher current, and electrode grounding resistance is often buried in a dry surface and is often quite large, which causes great difficulty in power supply. To effectively solve this problem and achieve the feasibility of high-power IP exploration, the authors took into account the increase of production efficiency, consulted the results of previous studies as well as production experience and, on such a basis, summed up and implemented a method for improving grounding resistivity in the dry thin-layer loose surface area, i.e., the use of wet soil buried porous sheet electrodes. The application of this method not only solves the problem of electrode power supply in such a region but also improves the efficiency of production. In addition, field exploration data quality is significantly improved and good effects can be achieved.

In order to solve the influence of different doses of explosive excitation on seismic data quality,the authors analyzed and tested the seismic data in indoor processing.Using such means as autocorrelation statistics,frequency statistics,and energy statistics of the seismic data,the authors found the correlation of explosive excitation weight and seismic wave characteristics and,by way of point-line-plane analysis,revealed the changes related to seismic data quality.On such a basis,the authors put forward the quantitative analysis and iterative processing technology in data processing and,by application of spherical divergence and absorption time and frequency domain compensation as well as the surface consistent amplitude and surface consistent deconvolution technique,the authors solved the problem of the influence of different doses of explosive excitation on the quality of seismic data with relatively satisfactory processing effect.The results provide reliable seismic data for the increasing production of the old oilfield in CY City

The surface-to-borehole IP method, as an actually widely used ore exploration means, has aroused a lot of interest among geologists both in China and abroad. In this paper, the authors probed into the IP effects of the surface-to-wells IP method on the regular orebody beside the well so as to solve the problem of predicting the exploration of the orebody beside the well and the blind orebody. In this paper, the authors mainly studied the spherical and the platy orebodies of different IP modes on the generated curve,and then explored multi-well cases. Finally, the authors discussed how to determine the spatial location of the orebody based on multi-wells law. The results obtained by the authors are helpful to the related research fields. In conclusion, reasonable construction method and proper quantity of observed data have positive effect on the prognosis of the orebody.

In the down-hole TEM forward simulation, previous researchers usually studied total electric field and analyzed response characteristics. In this paper, the authors studied the abnormal field with the down-hole TEM, and simulated the response of single conduction plate and multiple conduction plates. Meanwhile, the down-hole TEM responses of a three-dimensional conductive plate in a typical half space model were simulated to obtain a "fixed source survey at different drill holes" and "fixed drill hole survey at different source places". First, the authors conducted derivation of difference equation of secondary field and made numerical calculation by using the finite difference method. Comparative studies indicate that during the study of the abnormal field in the down-hole TEM, the abnormal field can reflect the position of anomalous space parameters. The results show that the abnormal response of down-hole TEM becomes weaker with time delay, but the abnormal response characteristics remain unchanged in different drill holes, and the abnormal response difference in different source directions is obvious. The measurement results can be used to judge abnormal body space location information. Finally, the main factors that affect the down-hole TEM abnormal response are the depth of the target body, the coupling relationship between the target body and the drill hole and the source position. The research results provide a theoretical basis for interpretation guidelines for related data.

People always tend to consider the metal ions adsorbed in geoelectric process as the formation mechanism of geoelectric chemistry (CHIM) anomaly. In this paper, contrast between major (Fe and Al) and trace elements' anomalies in several deposits was made. The result shows the high consistency between them. As we know, Fe, Al and other major elements are usually the main compositions of clay minerals. In addition, a large number of clay mineral particles whose sizes are from a few microns to tens of microns were found in the geoelectric foam plastic carrier through SEM observation. It can be accordingly inferred that the anomaly of CHIM is caused by fine-grained clay mineral particles that exist in soil, and these particles have electric activity and can be adsorbed selectively by CHIM process.

With the self-developed devices for in-situ soil sample preservation and desorption in oil and gas geochemical exploration and through optimizing the detecting conditions by such means as using saturated salt water or pure water, changing the sample weight, desorbing time, and negative pressure conditions, the authors obtained the best condition of analyzing. According to the experimental results, the method for in-situ soil sample preservation and desorption in oil and gas geochemical exploration was established. Precision waas used to evaluate the method. The result shows that this method has high precision, as shown by its good performance in a known area.

The prediction of oil-bearing sand of the second member of Eocene Shahejie Formation of Tuo 11 south area faces many problem.First,oil-bearing sand cannot be identified by seismic data because of the small thickness;Second,there exists difference of P-impedance between oil-bearing sand and water-bearing sand.Through the analysis of the geophysical characteristics of oil-bearing sand and water-bearing sand,the authors predicted the spatial distribution characteristics of oil-bearing sand using geostatistical inversion under the constraints of resistivity curve,and also predicted the oil-water interface.Inversion results have confirmed that the oil-water interface is at about the depth of 2237 m,which expands the oil-bearing area determined by early studies and is in good agreement with the results of the new drilling.Geostatistical inversion results have achieved good result in Tuo 11 south area for the first time,which widens the train of thought for the further exploration.

The submarine heat flow probe is a high-resolution, high-precision temperature measurement equipment, temperature calibration is carried out periodically which is an essential part to ensure the accuracy of the measurement data. The traditional temperature calibration is not applicable to Guangzhou Marine Geological Survey temperature gradient probe because of the size and other technical indicators of the submarine heat flow probes, design a calibration method based on US Seabird SBE 917plus type conductivity-temperature-depth system (CTD) which is suitable for deep-sea temperature measurement equipment. This method can be applied to check seafloor heat flow probe by sea trials, which provides a new checking method while the conventional methods can not be verified in the deep sea temperature measurement equipment. This method achieved good results in the offshore applications survey and broaden its applications, which can also be used to temperature calibration for other deep-sea temperature measurement devices.

In the pre-stack CMP gathers,the events of seismic reflection approximate a hyperbola.After a partial NMO correction,the seismic events approximate parabola.When the gathers miss some seismic traces,parabolic Radon transform algorithm can be used by the iterative to reconstruct and recover the missing seismic traces.Based on the basic principle of parabolic Radon transform,the authors put forward the calculation method of weighted parabolic Radon transform for the reconstruction and recovery of missing pre-stack seismic traces,and improved and optimized the weighted coefficients in the data domain.Test results of model data and real data show that the improved calculation method still has a robust reconstruction result even under the strong random noise,and the method does not produce false events,compared with the calculation method of the original weighted parabolic Radon transform,the method has the advantage of suppressing random noise,this is,the advantage of noise immunity.In addition,the calculation accuracy is also improved,and the algorithm has the characteristics of steadiness and high efficiency.

The spatial heterogeneity of carbonate fractured-vuggy reservoir is very strong in the Tahe oilfeild.Interwell reservoir prediction mainly depends on the application of seismic data.However,the results of deterministic seismic interpretation have multi-solutions.A geostatistical inversion method based on Markov Chain and Monte-Carlo algorithm is adopted for fractured-vuggy reservoir quantitative prediction and uncertainty evaluation.Firstly,geological prior information of the target zone can be obtained by geological regularity and deterministic interpretation results from well logging and seismic survey.Then,controlled by suitable geostatistical simulation parameters of the study area,the geostatistical inversion can be done, yielding many equal probability results of reservoir type volume and impedance data volume.Based on these results,the uncertainty of inversion can be analyzed.The method provides an effective seismic-driven way for quantitative prediction of fractured-vuggy reservoir,giving better solutions to the problems of the cave vertical depth positioning and the uncertainty evaluation of seismic prediction results.It is of great guiding significance for the modeling and characterization of fractured-vuggy reservoir.

General forward modeling expressions for right rectangular prism are derived from Newton's law of universal gravitation.In this paper, the authors dealt with reasons which lead to analytic singular points in the existing formulae and established non-singularity expressions based on the special integration method presented by Guo Zhihong.The validity of the new expressions was tested by model comparative study and theoretical analysis.

Because of using the two-way wave equation and zero-lag cross correlation imaging condition,RTM causes unwanted artifacts.In this paper,the authors introduced a denoising method using the Poynting vector,which is one of the methods denoising the artifacts of reverse time migration.This method utilizes the difference between normal and abnormal imaging points in angles between the source and the received wave propagation direction, which is based on the uniformity between the direction of wave propagation and its Poynting vector.As for calculating the Poynting vector,the authors smoothed the Poynting vector for those unable to use the formula and employed CPU/GPU heterogeneous parallel computation for intensive computation cost.Through the two-layer velocity model and Marmousi velocity model denoising image with different denoising angle ranges,the authors have reached the conclusion that the smoothing method used in this paper can improve the stability of Poynting vector calculation,that the application of CPU/GPU heterogeneous parallel computation can reduce the time of calculation,that the two-layer velocity model with the 70° max denoising angle is better,and that Marmousi with the 100° max denoising angle is better.

Radial point interpolation method (RPIM) is a kind of high precision meshfree method. As its shape function is constructed by interpolation method in combination with radial basis function, the boundary conditions can be directly loaded. This paper utilizes RPIM to the calculation of point source two-dimensional electric field. Firstly, the approximate principle of RPIM is introduced in detail and the discrete system matrix expression is deduced corresponding to point source two-dimensional variational problem. Secondly, background grid integral technology is briefly introduced and the influence of different number of gauss points on calculation accuracy of RPIM is discussed. Lastly, the optimal range of support domain dimensionless size and the shape parameter optimal value of RPIM are obtained through numerical experiments. Studies show that RPIM has robustness for solving point source two-dimensional variational problem, and the optimal α range is 1.0 to 1.2.

Although most of transient electromagnetic (TEM) apparatuses in China and abroad have taken various methods to suppress noise and improve SNR, noise may still remain in TEM data after stacking of all the periods. Stacking samples in time windows is an important technique for TEM data after stacking of all the periods. This paper proposes that Robust M Estimates methods can be applied to stacking samples in time windows. M Estimates are respectively adopted to process TEM data, and perform simulation and measurement in the field. The results and errors are investigated and compared.The experimental results show that M Estimates could effectively remove the Gaussian random noise and impulse noise, the M Estimates method is superior to the Arithmetic mean and geometric mean stack, and thus can improve the quality of data preprocessing.

In view of the problem of the Radon domain energy group energy leakage,this paper proposes a multiple attenuation method based on high-resolution Radon transform.The authors employed sparse constraint operator on the basis of conventional hyperbolic Radon transform,which can improve the degree of focus of velocity spectrum and better separate effective and multiple energy groups.Model and real data tests show that the proposed method is effective and applicable.

Based on the introduction of the principle of ground penetrating radar (GPR) and the processing of contaminated data with strong background noise, this paper shows some case studies of GPR with low frequency antennas applied in identification of lithologic boundary and weak geological body, detection of active fault and fissure, and delineation of riprap interface. These cases show that in order to obtain GPR data with high resolution, it is important in information collection, field reconnaissance, interference factor analysis, data acquisition, and comparison of data processing flows. The discussion in this paper is helpful to the deeper exploration by GPR with low frequency antennas.

Based on the difference of permittivity between water and rock media, the authors conducted forward simulation of two-floor geology at different depths of water by GPRSIM software. Under normal circumstances, when the radar antenna frequency is 50MHz, the exploration depth is about 10m. In combination with the geological data of the bridge site area of the Nanjing Yangtze River Bridge, the authors established the underwater sand model which contains water, silty clay, silty sand, gravel pebble and conglomerate, and made forward simulation of the model based on GPRSIM software. The result shows that, when the antenna frequency is 50MHz, the maximum depth of water is less than 4m, and each rock formation under the water has a good reflection. In particular, the geological radar can better reflect the thickness and distribution range of the underwater sand. The results achieved by the authors provide important theoretical basis for the actual exploration of the underwater sand.

The mineral exploration expenditures have risen since new millennium, but the discovery rates have not significantly improved. The discovery costs have been rising and have doubled in the last decade. Mineral industry have to progressively explore under deeper cover. The grim situation of mineral exploration promoted the development of geophysical technology, and has made great advances in the aspects of instrument equipment, data interpretation and inversion, potential application and improved success rate in discovery:higher sensitivity and accuracy, seamless collection of multiple data types, more accurate interpretation, greater the detection depth, a wider range of applications and improve the success rate of discovery. At the same time, the geophysical exploration methods have fully been using the latest achievements of information technology, and integrating with geology and other exploration methods in order to enhance the detectability and effectiveness of mineral exploration.

China has dozens of technological standards for geophysical and geochemical prospecting,which provide strong technical support for basic,public welfare and strategic geological work,and at the same time also provide the basis for the formation and establishment of geophysical and geochemical prospecting technical standard system.Through the study of the standard system of geophysical and geochemical exploration,the authors made a tentative discussion on the principles for the establishment of the standard system,the foundation of the establishment and the technological division,with the purpose of setting up the geophysical and geochemical standard system characterized by scientific classification,reasonable structure,and clear sequence. The results obtained by the authors have positive significance for the standardization of the exploration technology.

To tackle the status that the reservoir fluid seismic detection technique cannot easily recognize oil bed (containing no gas),it is of great significance to study the relationship between the seismic response and the oil-water saturability under the condition of the difference in oil and water weak elastic parameters so as to improve the success rate of the oil bed seismic detection.Utilizing the vector wave field digital simulation technique,the author performed wave field forward processing of the oil pool under the condition of different oil-bearing saturabilities and,using the inversion results,tentatively studied the seismic response characteristics caused by the oil-bearing saturability variation in the oil pool that contains only oil-water mixed fluid,so as to provide reference for the seismic detection and quantitative interpretation of the oil bed.According to the results obtained,the AVO response characteristics of the oil reservoir that contains only oil-water mixed fluid are basically consistent under the condition of different oil-bearing saturabilities,and hence it is difficult to use routine means to distinguish oil from water.Nevertheless,through suppressing non-oil and gas response in the reflection of the oil reservoir and making prominent the oil and gas response by amplitude correction,the seismic response resulting from the oil-bearing saturability of the oil reservoir can be clearly observed,and the seismic response characteristics in different oil-bearing saturability ranges are different and exhibit evident nonlinear features.In this way,the seismic data carry fluid information of the oil reservoir,and the utilization of the seismic data to detect the oil-bearing potential and oil-bearing quantity is feasible.However,the reasonable interpretation of the oil-bearing potential and saturability should be based on the prerequisite of the correct understanding of the nonlinear relationship between the oil-bearing saturability variation of the oil reservoir and the seismic response.

Based on the theory of "small intrusions forming large copper-nickel sulfide deposits" and the principle of rock magnetism,the authors chose the magnetic parameter Q value(the ratio of remanence intensity and magnetic intensity)closely related to the cooling rate of magma to study the thermodynamic ore-forming process of the Xiarihamu Cu-Ni sulfide deposit in East Kunlun,Qinghai Province.Statistics of 3682Q data from 90 drill holes in the Xiarihamu Cu-Ni sulfide deposit show that there exists no significant difference of Q values between intrusive rocks and metamorphic rocks,and there is no obvious high Q value zoning over the magma contact zone;the authors thus consider that hot baking was not serious in the magma contact zone due to the insignificant temperature difference between the metamorphic rocks and the magmatic rocks, which both lay in the deep underground.The spatial distribution of the Q values shows that the tectonic weak zone represented by the high Q anomaly belt has two positions:one is located in the lower part of the contact zone of the rock mass,and the other lies along the contact zone between the interior and the upper part of the rock mass.According to the Q values,it is inferred that fluid first penetrated from the lower contact zone,and then migrated into the contact zone between the interior and the upper part of the rock body.The fluid that penetrated into the weak tectonic belt might have played two kinds of roles:one was to dissolve sulfide minerals in the weak tectonic belt and thus had the ore-breaking effect,and the other was to perform infiltration and caused the migration of the ore-forming elements,thus exerting the ore-forming effect.However,the examples of applying magnetic parameter Q value to the study of the thermodynamic process are relatively less,and this paper is only an attempt to deal with this problem.

Based on magnetotelluric sounding results in combination with regional geology, the authors analyzed structural framework, structure and stratigraphic distribution of southern Tuquan Basin. The results show that the Tuquan Basin is a superimposed basin, in which Mesozoic strata were developed on the basis of late Paleozoic marine sedimentary basin, and late Paleozoic structure probably controlled Mesozoic sedimentation. The Tuquan Basin might be a compression type basin developed in the front of the overthrust nappe belt, and the two suites of low-resistance beds (Hongqi Formation and lower Permian strata) might be the potential hydrocarbon-producing strata.

In electromagnetic theory,conductivity and permeability are two important petrophysical parameters.The electromagnetic signal will inevitably be affected by the magnetic properties of the media in MT detection where magnetism is strong.The authors made the numerical simulation of the electromagnetic finite element method with magnetic susceptibility by introducing the magnetic susceptibility parameter into the two-dimensional MT forward theory.Prism model was established for calculation and analysis of the influence of the magnetic susceptibility parameters on the electric field,magnetic field,MT apparent resistivity and phase parameters.The numerical simulation results show that the high magnetic medium results in increasing the electric field,reducing the magnetic field,increasing the apparent resistivity,and complex changes of phase and,with the increase of the magnetic substance or the increase of the magnetization rate,the effect gradually becomes larger.The inversion results of geoelectric model with high magnetic middle layer are good.The results obtained by the authors provide a theoretical basis for the MT work in the high magnetic area and also have a certain significance for conducting the mineral prospecting in "the second space".

Located in the Eastern Tianshan-Xingmon geosynclinals system,the main body of the Xar Moron River fault zone is a WE-striking large-sized faulted structure extending along the Xar Moron River,and is also one of the larger faulted zones in Northeast China.The position of the fault has always been a hot topic in geological history.Now the research on the fault zone is mainly concentrated on the west region of the Da Hinggan Mountains,whereas the research on the east of the region is relatively insufficient.The authors analyzed the gravity magnetic and MT characteristics of the Xar Moron River fault in the east region of the Da Hinggan Mountains,separated the gravity magnetic fields by wavelet multi-scale analysis method,and inferred the location of the Xar Moron River fault.According to the images obtained that include the abnormal information and MT profile,the authors hold that the Xar Moron River fault is an ultracrustal deep fault.

The Sangkaropi ore district in South Sulawesi Province of Indonesia lies on the circum-Pacific volcanic island arc.It is one of the largest and high quality polymetallic deposits discovered in recent years, with mainly lead-zinc and occasionally copper-silver-gold resources.Firstly,the authors used spontaneous potential (SP) and induced polarization (IP) method to sieve superficial anomalies,and employed the transient electromagnetic section to evaluate the attitude and distribution of ore-related anomalies.The conclusion is that the major SP and IP anomalies lie at Bilolo,Rumanga and Medila and might be caused by concealed NW-trending gently-oblique tabular orebodies.Secondly,the authors compared the Sangkaropi deposit and the Kuroko-type deposit in Japan,and reached the conclusion that the Sangkaropi ore deposit was caused by Kuroko-type mineralization and geological structure,and hence has the characteristics of both Kuroko-type deposit and linear mineralization.Finally,the authors made a suggestion for prospecting on the basis of geophysical anomaly,Kuroko-type deposit characteristics and geological structure.The results obtained by the authors are helpful in the search for similar deposits in peripheral areas.