The Xiarihamu deposit is the first superlarge magmatic liquation type Cu-Ni sulfide deposit discovered in recent years in East Kunlung area of Qinghai Province. During the process of its discovery and evaluation, the integrated geochemical exploration methods played the most important role. Based on the systematic evaluation of 1:200 000 stream sediment anomaly→1:50 000 geochemical characteristics of stream sediments→1:10 000 composite anomaly→combinational method of geology and engineering verification, the authors found that 1:200 000 stream sediment survey could approximately delineate the prospecting target, but the corresponding geological work failed to find the Cu-Ni ore-related basic and ultrabasic rock bodies, and the origin of the anomaly could not be determined. 1:50 000 stream sediment survey further decomposed the 1:200 000 stream sediment anomaly. The corresponding geological work found some basic-ultrabasic rock bodies related to Cu-Ni ore, but the ore potentiality needs further confirmation. The 1:10 000 soil survey further reduced the prospecting target, and supported by the 1:10 000 geological sketching, the main causes of anomaly were detected and the ore-bearing basic-ultrabasic rock bodies were delineated in detail. All of these results have provided the direct basis for further engineering verification. It is held that this combinational method is the most economical and fastest way to find the orebody, and the results obtained by the authors could be regarded as an example to evaluate some deposits similar to the Xiarihamu deposit in the metallogenic belt.

Aimed at investigating the geological conditions and the modes of occurrence of gas hydrate on the northern slope of South China Sea, the authors established a three-dimensional interval velocity model based on the three-dimensional seismic data and stacking velocity spectrum under the condition of lack of logging data, and then transformed the data to low impedance background model. Subsequently, the authors extracted pseudo wells and tied them accurately, and finally obtained an absolute impedance and fine velocity bodies by the constrained sparse spike inversion method. Meanwhile, the authors comprehensively utilized seismic and inversion data,analyzed the best threshold value for distinguishing the gas hydrate in the study area and, on such a basis, quantitatively interpreted the gas hydrate. The results obtained show that:First,the velocity of gas hydrate is about 2050~2150 m/s, and P-impedance is above 3.9×10⁶ kg·m^-3·m·s^-1 in the study area,which are higher than the velocity and impedance of surrounding rock;Second,the distribution of gas hydrate is extensive, especially in the middle west and southeast region,where the preliminary estimated maximum thickness is up to 48m.

The weathered crust reservoir of Ordovician Majiagou Formation in the Sulige gas field of Ordos Basin is characterized by thin thickness,strong inhomogeneity and complex gas-water relation,and the reservoir development is aeffected by multiple controlling factors such as deposition,digenesis and structure,which causes the difficulty of the exploration.Taking the M5₁³ Sub-members of TAO7 block as an example,the authors specially studied the weathering crust reservoir by the application of analysis technology of modern volumetric attributes.Combined with the development characteristics and the geophysical response characteristics of crust reservoir,the study included improving the SNR of original seismic data with structure-oriented filter and comprehensively predicting the micro faults using volumetric curvature and ant tracking on the basis of filtered data.The karst grooves were described by strata slice and volumetric fusion.The prediction result shows that the analytical technology of modern volumetric attributes could elaborately describe the karst reservoir by using the routine seismic data more sufficiently and reduce the prediction multiplicity.Several techniques and methods have a high goodness of fit as proved by drill wells and provide a good basis for the further petroleum exploration in the study area.

With 1:50 000 high precision gravity,magnetic and magnetotelluric sounding,the authors measured the Sinian-Lower Paleozoic marine strata on the west side of the Xuefeng Mountain.Combined with the characteristics of drill hole,geological data and physical property statistics,the authors made positive and negative interpretations on the acquired gravitational,magnetic and electrical data,thus interpreting the fracture structure and strata spatial distribution characteristics,explaining the distribution of strata,buried depth and thickness and predicting the favorable oil and gas reservoir structural belt.The results show that,with the disturbance of complex geological settings,human activities and industries,the integrated gravitational,magnetic and electrical geophysical methods can maximally reduce the uncertainty of geological interpretation and accurately identify the distribution,fold,fault and local structure of Sinian-Lower Paleozoic marine strata in this area,and thus can play a vital role in oil and gas prospect evaluation.

As the largest coal-bearing area in Ningxi,the east Ningxia(Ningdong) area has nine Permian-Carboniferous and Jurassic coal fields.According to the characteristics of these two types of coal fields in the Ningdong area,the authors established the 2.5D gravity field model from the forward modeling.The coal-bearing area could be identified and separated by the potential field separation method based on the 1:200 000 gravity data.It is found that the first to third wavelet details correspond well with the known coal fields after applying the wavelet analysis to the Bouguer gravity anomaly,while the local gravity anomalies derived from the slide averaging method have no obvious correspondence with the known coal fields.Therefore,the wavelet analysis of the gravity data has good performance in predicting the Permian-Carboniferous and Jurassic coal-bearing area.And at the same time,the use of the 1:200 000 gravity data is maximized for the coal field exploration.

In order to improve the gold metallogenic research level of the Huaihua area,the authors carried out metallogenic prediction of gold deposits with weighting of evidence based on MRAS for the first time in this paper.The multiple geological database in Huaihua area was built based on the data of geology,mineral resources,tectonics,geophysics,geochemistry and remote sensing.The regional gold prospecting model of the study area was built on the basis of systematical analysis of metallogenic characteristics of the gold deposits,and the prediction factors included Neo-Proterozoic strata,faults,aeromagnetic (ΔT) anomaly zones from 0 to -60 nT,Au-,Cu-,Pb-,Sb-,Zn geochemical anomalies,igneous rocks,remote sensing interpretation of the linear and ring-shaped structures,gravity anomalies from 5 to 20 mGal and from 30 to 55 mGal,gold heavy sand anomalies and other heavy sand anomalies.The study area was divided into 2.5 km×2.5 km blocks firstly,and then the posterior probability of the block unit was calculated.According to the cumulative frequency distribution features of posterior probability,the block units were classified into A,B or C levels.In addition,10 gold prospecting targets were delineated according to the geological features and distribution characteristics of the block unit.Finally,according to the mean posterior probability,the size of the prospecting target and the sites of the discovered gold mineralization and deposits (ore spots),the prospecting targets were divided into 4Ⅰ-level targets , 3Ⅱ-level targets and 3Ⅲ-level targets.

According to the study of elements in the Ⅳ-3 orebody of the Saibagou gold deposit, the authors hold that the primary halo displays the feature of axial zoning. Its front halo, near-ore halo and rear halo are distributed disorderly, and exhibit obvious reverse zoning. Along the axial zoning, Au and Ni show good linear correlation. The existence of front element (Hg) indicates that the space of downward extension is large. Compared with the geochemiscal data of axial zoning, the depth of the orebody increases gradually, and geochemistry displays the characteristics of rise-fall-rise. These data suggest that the orebody extends downward considerably from 3 162 m. On the basis of this study, the authors formulated an ideal model of superimposed halo and extracted geochemscal information for the prediction of small ore deposits in the surrounding areas.

Soil geochemical survey was carried out in Property A in Kasempa of Northwestern Province of Zambia, and the distribution, concentration, correlation, and fitness of single elements Cu, Co, Ni, Au, Ag, As, Pb and Zn in the surveying area were analyzed. It is considered that the best prospective guide elements are Cu-Ni-As-Co-Zn, so a composite anomaly of Cu-Ni-As-Co-Zn numbered as Ht-1 was delineated with weighting method, which is believed to be an anomaly related to mineralization. Later it was found that anomalies with magnetic high, high polarization and low electric resistance were consistent with the geochemical anomalies through IP survey and high-precision magnetic survey. Two verification holes were drilled and intersected the commercial orebody, which led to the discovery of a medium-size copper polymetallic deposit.

The granite type uranium deposit mainly occurs in the interior or at the edge of a rock body. The investigation of the developmental conditions of a rock body thus has significance for uranium deposit exploration. The controlled source audio frequency magnetotelluric (CSAMT) method and its applications in Weijing area were described in this paper. Based on geological data and rock resistivity as well as CSAMT data, the authors found the thickness of the granite rock mass and the deep development of the contact zone between the granite and the metamorphic rock, and the good results were verified by drilling. A comprehensive analysis shows that CSAMT method has fairly good resolving power in vertical direction. According to results of CSAMT method, the authors detected the thickness of rock bodies as well as the position and the deep characteristics of structures. In addition, the distribution characteristics of the zones of fractures, fissures and vein bodies were detected too. The CSAMT method is an effective means for uranium deposit exploration.

The Hunan-Jiangxi border area is a complex tectonic domain with multiple orogeny and tectonic superposition.Meanwhile,it is also the main producing area of nonferrous metal deposits,polymetallic deposits and uranium deposits in southern China.Due to the influence and restriction of many factors,the study of geological structure is very insufficient.Combining the regional gravity data with the latest high-precision airborne geophysical(magnetic/gamma)data,the authors systematically investigated the geological structure of this area,probed into the distribution characteristics of deep faults and their relationship with magmatic rocks,and described distribution condition and geophysical characteristics of the Qinzhou-Hangzhou junction area.The results have a strong reference value for the further development of basic geological research and mineral resource prediction in this area.

Located in eastern Central Asian orogenic zone, the Olji area belongs to the lead, zinc, silver, copper, tin, iron metallogenic zone of southern Da Hinggan Mountains. Permian Dashizhai Formation in the study area is an association of metamorphic volcanic rocks interbedded with clastic sedimentary rocks. The volcanic rocks have the characteristics of typical asymmetric bimodal volcanic rocks, and the basic peak is strong. The study of rock geochemistry indicates that intermediate-basic and intermediate rocks belong to quasi-aluminous and calc-alkaline rock series or low potassium (tholeiitic) rock series, intermediate rocks belong to shoshonitic rock series, and intermediate-acid rocks belong to peraluminous and calc-alkaline rock series. The rocks were formed in an island arc environment of continental margin rift basin in middle-late Hercynian period. Dashizhai formation volcanic rocks are enriched in Ag, Sn, Pb, Zn, Cu and other metallogenic elements, and constitute the source bed of Pb, Ag, Sn, Zn and other metallogenic elements in the study area. The metallogenic potential of Dashizhai Formation volcanic rocks is huge. Combined with previous research, the authors hold that Dashizhai formation volcanic rocks are the best place in search for volcanic hydrothermal lead-zinc-silver-copper deposits.

Based on three-dimensional current source inversion tomography, the authors applied the self-potential data obtained in the research site of Zhongshan Botanical Garden in Nanjing to study the medium structure in the vadose zone. The medium structure revealed by current source tomography accorded with the results from ground penetrating radar. This indicates that three-dimensional current source tomography can be used to detect the medium structure in the vadose zone, thus providing a new geophysical method for investigating ground medium structure.

In order to ease the growing contradiction between mineral resources supply and demand and realize the effective exploration of the complex terrain region, it is urgently necessary to improve the computational efficiency and interpretation accuracy of the ATEM (Airborne Transient Electromagnetic) system. In this paper, the authors used differential conductance and synthetic aperture algorithm to realize fast imaging for ATEM system. In order to further improve the resolution and interpretation accuracy, the authors made an in-depth study of the key technology of synthetic aperture algorithm. Firstly, the authors provided a method for calculating the optimum aperture, and further verified that the aperture size could significantly influence the imaging effect. Then, by using numerical simulation method, the authors calculated the function expression of optimum aperture based on a lot of model calculation results. Finally, by using a multiple model example, the authors confirmed that the synthetic aperture imaging method can effectively improve the resolution both in lateral and vertical directions. This method is not affected by the impact of the massive air data and also has the characteristics of fast computing speed and can be used for real-time imaging. It can further improve the interpretation precision of the airborne transient electromagnetic method. The research results enrich the ATEM interpretation method and provide an important theoretical basis for improving the prospecting precision.

Radon transform is a kind of technical method widely used in seismic data processing,but there are problems of low resolution and low computational efficiency in practical application.On the basis of phase shift hyperbola,the authors deduced time-invariant hyperbolic integral path,proposed sparse hyperbolic Radon transform based on Bayes principle,provided parameter selection principle of discrete transform,and introduced dynamic time windows to ensure the condition that reflection waves of different layers have the best convergence.Sparse hyperbolic Radon transform in the frequency domain has higher resolution and it can be realized in the frequency domain,so the computational efficiency can be drastically improved.Model data test and actual application result show that sparse hyperbolic Radon transform in the frequency domain can effectively remove regular interference,suppress random noise and improve the signal-to-noise ratio;in addition,it also has better fidelity and amplitude preservation.

It is difficult to detect the complicated 3D structures by only using a single grounded source, as it could only generate single direction current vector and will have distortion sometimes. Therefore, the authors use the electric dipole sources transient electromagnetic tensor method, which is suitable for detecting 3D structure. In combination with numerical models, the authors present the data with the tensor apparent resistivity It is found that in uniform half-space and layered earth, the coordinate invariant P₂ has a good representation for the change of underground media. In 3D model, the coordinate invariant P₂ and ellipse are formed by the coordinate invariant ρ_min and ρ_max, which are calculated for 3D resistivity models. The authors hold that profiles of LOTEM measurements across a 3D cube structure can be used to accurately reflect the changes of the 3D structure and sketch the anomaly boundary. All of these results provide theoretical guidance for further TEM data interpretation.

Since the study of the brittleness anisotropy for shale rocks is relatively rare, it is necessary to study the corresponding brittleness characteristics of the shale reservoir. Therefore, the authors construct an effective medium model to link elastic properties and brittleness index of shales to complex constituents and specific microstructures. Based on upscaling modeling, the authors sequently construct the nano-porous clay composite, submicron organic-rich clay composite and micron dry rock matrix by introducing clay particles. In consideration of the factors such as bound water and adsorbed gas in nanopores, the authors construct an effective medium model of shale reservoirs to characterize the elastic parameters, which improves the construction process based on DEM and Gassmann theory. Then, the anisotropic expressions of Young's module and Poisson's ratio based on elastic modulus parameters are derived by using the transition matrixes M and Bond conversion. Finally, the anisotropy features of shale rock's brittleness and the seismic response are summarized with different mineral constituents. Brittleness analysis shows that the brittleness in the direction that is parallel to the strike and perpendicular to the bedding is 2.5 times that perpendicular to strike and inclined to bedding at a 45 degree and the rock brittleness has increased, which suggests that the rock is more likely to fracture with increasing quartz content and decreasing clay content. These results provide a reference for predicting reservoirs' brittleness and designing hydraulic fracturing.

On the basis of previous work, the authors collected 1:200 000 regional geochemical data along the northern margin of Qaidam Basin,used fractal (multifractal) method to determine geochemical anomaly characteristics in Gobi desert area of eolian sand, and adopted the C-A and S-A model to investigate the characteristics of geochemical anomaly of Au element influenced by eolian sand in the Gobi desert area. The results show that C-A model has advantages in determining the threshold but still has some limitations. S-A model can well eliminate the background field and interference factors, reduce the area of anomaly, and can make prominent the small weak anomaly. The method of extracting the region of anomalous elements can be used to identify the vast majority of known ore deposits and indicate the further anomal anomaly area of ore-forming elements based on the geochemical data, thus providing a reference for further exploration.

The analysis of geoelectrochemical foam carrier often suffers from the lack of effective analytical quality control methods, which would limit the application and extension of the geoelectrochemical method. In this paper, the experiment of adding standard solution to the blank foam was conducted to meet the analytical quality monitoring of the widely used foam pretreatment means of ashing method. The results show that this method would solve analytical quality monitoring for Au, and the accuracy of analysis can even be higher than the requirements of soil analytical accuracy in multi-purpose regional geochemical survey. In contrast, there are varying degrees of elements' loss during the ashing process for Cu, Ni, Pb, Zn, therefore this method is not suitable for these elements.

In land seismic survey, the seismic data are mostly contaminated by ground-roll, which reduces the signal-to-noise ratio and impacts the quality of the seismic data seriously. The least-squares filter is a new means to suppress ground-roll, which is different from normal domain filter. The main principle of the method is the utilization of the convolution of scanning signal and filtering factor to predict ground-roll. It is necessary to construct the objective function to calculate the filter factor. The objective function is the least-squares error of seismic data and ground-roll. In that way, the targeting functionally obtained minimum can calculate filter factors from seismic data. The last step is to continue the second ground-roll suppression by making the extracted ground-roll as the input, which can get the seismic data and wipe out the ground-roll. In this paper, nonlinear sweep signal was used to extract ground-roll, and the sweep signal's beginning-ending frequency was analyzed. The results prove that the proposed method can effectively suppress the surface wave through synthesis of field data.

In the shallow area,the seabed related multiples can't be depressed effectively by use of conventional SRME method because of the shallow water depth and the lack of reflected signal from the seabed.Predictive deconvolution is often used for multiple wave suppressing,but deconvolution will destroy valid reflected signal whose wave cycle is similar to the seabed multiple; particularly in the hard seabed,the amplitude of the seabed multiple wave energy is stronger than the seabed reflection, and in this case,the method of predictive deconvolution cannot depress seabed related multiples entirely.In this paper,seabed related multiples depression by using the DWD + SRME combination method and DWD method is adopted for attenuating short period seabed related multiples,and the SRME method is used for suppressing long period free surface related multiples.In addition,the method of radon transform is used for removing inter layer multiples.The results show that the seabed related multiples have been depressed effectively by the combination method of DWD + SRME,and the shallow effective reflection signals are not harmed,the deep reflection signals appear gradually because interlayer multiples are attenuated by using Radon transform method.It is therefore held that the adoption of the combination method of DWD + SRME and Radon transform technique is a feasible multiple depression technique for the low SNR seismic data in the shallow water.

The area of seismic exploration is often located in remote areas, and is always lack of terrain data. The digital elevation model data of Google Earth (GE) are based on SRTM and have a high precision. Based on the batch extraction of elevation data from GE, the authors analyzed the accuracy of elevation data between mountains and plains. The results show that GE elevation data and actual elevation data are consistent with each other whether in the mountains or plains; The accuracy of elevation data in plain area is higher than that in mountain area. The elevation data from GE can be used to produce contours and analyze the system parameters.

In order to simulate the actual geological conditions, the authors present the least squares inversion by incorporating topography into a forward model. In consideration of an ill-posed inverse problem of MT, the authors introduce Tikhonov regularization to obtain the equation of the total objective function and utilize smoothness-constrained least-squares inversion to solve the total objective function. As the regularized factor controls resolution and stability of the inverse problem, the authors put forward active constraint balancing (ACB) to obtain an optimized regularized factor that balances the resolution as well as the stability of the inversion process. Meanwhile, for the purpose of speeding up the calculation of the field Jacobian for 2-D magnetotelluric inversion, the principle of electromagnetic reciprocity is applied. Finally, the authors discuss the inversion results of TE mode, TM mode and joint inversion of TE and TM mode using some synthetic models, in comparison with some of previous work.

At present, the inversion of controlled source audio-frequency magnetotelluric data is mainly based on the isotropic media. Because of the rock fracture or the shape of mineral, the resistivity is different in each direction in the complicated geoelectric body. To fit actual geological conditions better, this paper mainly probes into the inversion of controlled source audio-frequency magnetotelluric data in layered media with azimuthal anisotropy induced by ground orthogonal horizontal electric dipoles. We develop an Occam inversion algorithm to invert controlled source audio-frequency magnetotelluric data for azimuthal anisotropy in layered media. Designing the theoretical geoeletric models, the synthetic examples demonstrate the validity and stability of the Occam inversion algorithm. At the same time, the inversion results of different data suggest that in order to get better inversion results of azimuthally anisotropic layered media the apparent resistivities ρ_sxy,ρ_syx, and phases φ_xy,φ_yx, should be used.

Researchers have always met with problems like lack of geomagnetic data when processing magnetic data,so it is necessary to estimate geomagnetic data in appointed area.Based on an analysis of diurnal geomagnetic correction with multi-observatories,the authors have found that geomagnetic data of different observatories are linear,so the formula of estimating geomagnetic data can be fitted by importing regression,and then the effects of the method can be checked by using observed data.The reliability of the method is confirmed,which is a progress in data processing.

Values of heavy metals from the 100 surface sediment stations in western Bohai Bay were determined, and two methods were used to evaluate the sediment environment. The results show that the average values of As, Hg, Cu, Pb, Cd in the surface sediments are 12.9×10^-6, 0.031×10^-6, 29.5×10^-6, 27.4×10^-6, 0.159×10^-6. The indices of geoaccumulation show that, in the high value area, Pb and Cu reach the slight pollution level. The potential ecological risk indices show that Hg and Cd have reached moderate ecological harm, while in the study area, the harm degree sequence of the five heavy metals is Hg> Cd> As >Pb> Cu.

With a municipal and county-level agricultural geological survey in a typical eastern region of Hainan Province as a case study, the MapGIS-based Label point method is introduced for sample point layout. The lands involved in the second land use survey of Hainan Province are incorporated into 10 categories comprising dry land, paddy field, orchards, other gardens, woodland, construction land, mudflat, traffic area, water surface and other land, and the number of pattern spots is reduced from 9,932 to 4,257 after the incorporation; then, the incorporated pattern spots are divided into three levels of A, B and C with descending representativeness in accordance with their area sizes; during the layout design of sample points, the traditional 500 m × 500 m grid method is adopted for Level-A pattern spots, the MapGIS-based Label point method for Level-B pattern spots, but no sample point layout design for Level-C pattern spots. After an automatic arrangement of sample points is carried out by software and necessary manual adjustment is conducted, a total of 1,610 sampling points are arranged in the working region covering an area of 174 km², and the density of the sample point reaches 9.25 point/km², which meets the relevant requirements of the agricultural geological survey. The validation test of the method suggests that, compared with the traditional 333 m×333 m grid method of sample point layout, the method proposed in this paper has significant superiority in workability, representativeness, accuracy and reasonableness and hence deserves extensive promotion and application.

when a precise exploration technology was realized by a borehole-to-surface electrical prospecting as CT scans of medical images, the technological of the geoelectrical resistivity survey had progressed into a high phase of the comprehensive quantitative interpretation, more geological exploration projects have historically been hard problems to solve, they can be completed. The article describes a example of the precise geological exploration about successful application of the surface-to-borehole electrical resistivity tomography survey, when collapses of karstic geology were occured in the stage of construction, to ascertain complex karstic geologies at a short time, a low cost and high efficiency. so that survey results provides the reliable geological data for the disclosed hidden trouble of karst geologies, the designs of the treatments and the technology of karst foundation treatments.

This paper deals with the application of ultra-high density resistivity method to the detection of buried fault in the dam area of a reservoir, and describes geological situation of the survey area and the layout of surveying line as well as the detection mechanism of the method. On such a basis, apparent resistivity response of layered medium models is simulated by Hankel transform method. Based on inversion calculation combined with the geological drilling data, the buried depth of bedrock and the trend of regional fault are determined.The fault fracture zone presents obvious vein-like low resistivity anomalies in the middle of resistivity sections, which is consistent with the geological and drill hole data, thus verifying the effectiveness of the ultra-high density resistivity method.

Based on the research of controlled source audio-frequency magnetotelluric sounding and NLCG inversion method in this paper, The author analyzed the electrical constraint inversion method which used drilling, logging, geology, seismic, high density resistivity method as a kind of priori information,and combined the measured CSAMT data of a tunnel in the BAOLAN railway, contrasted and analyzed the result which used or not used the electrical constraint inversion, finded the constraint inversion results had a higher accuracy in finding fault, weathering, lithologic and determineing the boundary thickness.

Water zones adjacent to coal seams seriously threat coal mine's safety in production. In the mining process along No. 1171 roadway, water content significantly increased in the front. In order to avoid the water disaster, the authors carried out measurement on the whole working face. Transient electromagnetic measurement was chosen, and ground and underground coal mine transient electromagnetic combined exploration was conducted in water-rich area. The flood range was controlled in plane by ground transient electromagnetic method, and the underground water-rich area was delineated by using downhole detection method, so as to guide further pumping and drainage work and reduce the possibility of water damage. The results of the ground and underground transient electromagnetic fields are the same, and the results of the water-rich areas are also he same. The combined detection reduces the possibility of multi-solution of geophysical prospecting data and thus can greatly improve the exploration precision. It can improve the reliability of the coal mine prevention and control.