In the light of typical coneshaped columns in the Lu'an mine of Shanxi Province, the authors

established a mathematical model for the collapse column, and used the wave equation model for

seismic ray tracing and wavefield simulation of collapse columns. The simulation results show that,

due to the special nature of the collapse columns, such waves as the normal reflected wave, the fault

point diffraction wave, the delay diffraction wave, the delay reflected wave and  the "diffraction

wave" consisting of Pwave field are formed around the collapse columns. On such a basis, the field

shot was simulated, and then a single shot record for routine processing  was generated to produce

stacking sections and migrated sections. The forward section and the actual data analysis reveal that

the fallen columns of the special wave constitute an important feature for recognizing collapse

columns; nevertheless, the resultant scale of the actual seismic data interpretation is often smaller

than the scale of actual collapse column. Some suggestions are also put forward for reference.

Low density geochemical survey in Yishenjilike mountain area led to the discovery of a huge gold geochemical block, and the verification and evaluation of gold anomalies led to the discovery of the Bogutu gold deposit. In combination with the geological characteristics of the prospecting area, the authors carried out a series of geological-geophysical-geochemical exploration work, delineated quite a few geochemical and IP anomalies, and detected the characteristics of ore-bearing structural belt. Through trenching and drilling verification, the authors found more than 40 gold orebodies, thus achieving good ore-prospecting results.

A review on the airborne gravity survey and airborne magnetic survey are given in this paper. The

authors hold that these techniques have entered into a new development period, as evidenced by the

emergence of such technologic indicators as airborne vector magnetometry, magnetic fulltensor LTSSQUID

and HTSSQUID gradiometry, airborne gravimetry, gravity gradiometry and geophysical survey by UAV.

This paper gives a brief review of the history of the airborne gravimetry. Based on the principle of the airborne gravimetry, the paper deals emphatically with the history, the present  research situation and the developments of the airborne scalar gravity survey system. Further development trends are also indicated.

 With powerful Matlab image processing functions, this paper has realized the 3D display of ground penetrating radar data, whose procedures are simple to prepare and easy to learn. A detailed description of the code is given, and the three-dimensional test data show that, by setting transparency, the target can be displayed in an intuitive and visual way.

This paper puts forward a new method for calculating anomaly area—the polygonous approximation method,and gives corresponding algorithm and precision controlling technique.With this method,one can calculate anomaly area rapidly and precisely,thus yielding relatively satisfactory results.

IP is an important method for mineral resources exploration, but it can only be applied in a few pivotal places because its difficult performance, and hence the information obtained from the survey area is very limited. The aim of this study is to find a simple and effective IP method with which we can get much valuable information form the survey area so as to improve the exploration effect. In the Yinan gold ore district, the authors applied the gradient sounding profile method, calculated 2D resistivity and obtained the IP model. The results show that the gradient sounding profile method is simple and effective.

In drawing the contour map of geophysical data, suitable gridding methods should be chosen according to objective

environment characteristics and characteristics of data themselves. With practical examples, this paper deals with some common

gridding methods such as inverse distance to a power, Kriging, Minimum Curvatrue, Nearest Neighbor, Polynomial Regression, Radial

Basis Function, and Triangulation/Liner Interpolation, probing into their choosing means, applicable fields and parameter

installment.

The R-mode cluster analysis is a mathematic statistical method for obtaining the quantitative similarity of several elements. Its procedure includes: the conversion of the original data; the solution of the relevant coefficient ; the clustering of the result. The above operation can be realized by using the data analysis tool of Excel. This method is quite suitable for field utilization.

This paper has described and reviewed the pinciples,expermental set up and observational results of applying atom interferometer to measuring the earth's gravitational acceleration.This method was developed by Nobelist Steven Chu,M.Kaservich,A.Peters et al.,who demonstrated a resolution of 10^-10.The application of this technique to geophysics and the related problems are also discussed.

As an important prospecting technique and an effective means for obtaining mineralization data,

geochemical exploration has been proved to be very successful in mineral exploration. This paper focuses on

commenting the present research situation and application effect of some new methods such as structural

superimposed halos method, heat released mercury method, separatory electrogeochemistry method, enzyme leach, and

geogas and selective leaching of mobile metals method. It is emphasized that any one of these methods has its

unique applicability and that, in the practical application, we should pay attention to the cooperation of

geochemical exploration, geologicalgeophysical exploration and remote sensing and depend on the study of

geological background so as to demonstrate the usefulness and effectiveness of geochemical exploration.

According to the data obtained from air-borne electromagnetic and magnetic survey and

ground two-frequency IP and magnetic survey, this paper discusses the relationship between the

features of air-borne and ground geophysical composite anomalies and the ore resource distribution.

On the basis of an integrated analysis, geophysical composite anomaly criteria in search for iron, zinc

and lead deposits were established, and 12 important ore-prospecting targets were delineated, which

provides very important clues for finding iron, zinc, lead and some other ore resources.

Porphyry copper deposit is the most important copper deposit type in China. With the deepening of mineral exploitation, exploration geochemistry in mineral exploration has become increasingly important. Based on related literature, this paper sums up the exploration geochemical research results of porphyry copper deposits, which include such aspects as geochemical characteristics, exploration methods, anomaly evaluation and prospecting indicators. Exemplified by the Fujiawu copper deposit, this paper reports the latest advances in the study of porphyry copper deposits.

 Numerical integration of Hankel transforms is effective tools for EM Sounding 's forward numerical simulation, this paper made out formula derivation of numerical integration of Hankel transforms by digital filtering, and use digital coefficients to do numerical compute which was put forward by Guptasama and Singh，finally contrasted to theoretical resolve expression and analyzed this algorithm's error distribution. The results show that the calculation of this algorithm continuously approximate its theoretical solution, it has no oscillation, high precision and great practical value in the numerical simulation study.

In this paper, recent advances in the research and development of quantum magnetometers have been described together with some suggestions on further research work.

Element abundances of the continental crust and rocks cited in the past and recent literature have been based on compilations of data from various studies. This leads to uncertainties in sample representativeness and data quality. The present study is based on systematic collection of 28 253 individual rock samples over an area of 3.3 million km² in eastern China, east of eastern longitude of 105°.The sampling involves more than 800 igneous intrusive bodies and metamorphic complexes as well as more than 500 type stratigraphic sections. From the individual rock samples, 2 718 composite samples were made and analyzed for 77 elements by 15 specific methods, dominantly XRF and INAA. Analytical quality was controlled by international and national preliminary geochemical reference materials of GSR, GAu and GPt series. Synthetic results from geological, geochemical and geophysical studies were used to construct crustal constitution model, from which element abundances of the continental crust in the North China platform, the upper crust and exposed crust in eastern China, chemical composition of igneous rock in China and of sedimentary rock and metamorphic rock in eastern China were derived.

 Vibroseis exploration, as an important method of seismic exploration, has become increasingly valued by geologists. During the field work, different geological conditions need different parameters, and the choice of suitable excitation parameters has become a very important problem. This paper mainly introduces six kinds of parameters, namely numbers of controlled seismic source, scanning bandwidth, vibration period, scanning length, scanning slopes, and vibration rate. The influence of these parameters on the quality of seismic records was studied in detail, and the simulation of the proper parameters was performed in Jiulishan area to enhance the resolution of vibroseis exploration and improve the signaltonoise ratio of seismic records.

Based on two-dimensional Fourier transform and half-wave theory, this paper has studied the seismic Rayleigh wave dispersion curve extraction in f-k domain and made this theory fit in with a program by means of Delphi7.0. It is concluded that the f-k method overcomes the shortcomings of the one-dimensional digital processing technology and makes full use of multi-channel Rayleigh wave data record.

Migration velocity analysis and migration imaging constitute two important parts in seismic data processing. At

present, time migration has become mature, and depth migration is getting more and more perfect. The common method for time

domain migration imaging is pre-stack time migration. By adopting stacking velocity analysis along the layer, exact layer

stacking velocity can be obtained. Through dip correction, pre-stack time migration and CRP de-migration velocity analysis, the

velocity is optimized step by step, and then a desired RMS velocity field that is up to the geological rule is acquired. In

addition, the method for building the accurate migration velocity field is summed up through the study of the depth migration

method. A new seismic data processing flow in combination of Kirchhoff arithmetic based on ray tracing and wave equation

arithmetic based on wave field extrapolation is presented. As a result, migration velocity analysis and migration imaging are

considerably improved.

The implied contour level and color scheme in Surfer software fail to express the subtle difference of DEM and the effect

of color solid. In addition, the artificial setting of the levels and color values are timeconsuming and laborious, and the

results are sometimes not perfect. With the consideration of contour level and color scheme and on the basis of Surfer platform

automation technology, this paper presents a program that can automatically generate a level file with different intervals and

different colors, thus resulting in satisfactory effect and efficiency.

This paper proposes an equivalent second order elastic wave equation to solve the problem of being unable to completely

separate the coupled P and S wave by full elastic wave equation. Through solving this equivalent wave equation by high-order

staggeredgrid finite difference scheme together with Flux Correction Technology (FCT) and separating wave fields of the

isotropic model and layered model, the authors accurately obtained the hybrid wave field and completely separated fields of pure

P wave and pure S wave fields. An analysis of the numerical results shows that the method is effective and reliable in isotropic

media, and there exists abundant energy transform information in separated pure P and pure S wave field. The result of the study

is of significance in understanding the propagating law and the elastic wave theory in the complex wave field.

On the basis of mote than230 English and Russian papers or monographsissued in the last 30 years as well as nearly 50 Chinese articles published overthe past 10 years on the inversed problem in g avity and magnetic explora-tion, combined with his practice in the study of the inversed problem, the all-thor expounds the inversed methods in gravity and magnetic exploration cur-rently used both at home and abroad, briefs the readers about the researchsituation in China and foreign countries, and makes a detailed review on achi-evements gained in China in comparison with the research levels abroad.Final-ly, suggestions are put forward concerning some subjects which are worthnoticing in future research work.

This paper has put forward the idea of utilizing Surfer to draw the initial data profile-plan. The programme compiled can realize the construction of Bln file. The profile-plans for regular net and irregular net have been constructed, and the results are satisfactory.

The algorithm of the finite difference oforder velocitystress staggered grids has been built, which is

suitable for the perfectly matched layer (PML) absorbing boundary for elastic media. Meanwhile, the construction of the

PML absorbing boundary condition and the realization of the finitedifference algorithm are discussed in detail. Wave

field modeling calculations show that, compared with the conventional decaying exponential absorbing boundary and non

absorbing boundary, the PML absorbing boundary can perform absorption much more clearly and absorb the boundary

reflection from various angles, whose absorptivity (the ratio of absorption energy to unabsorbable energy) can reach

99.99%. The PML absorbing boundary can well eliminate the periodic folding effects, which makes the calculation of the

wave field characteristics very distinct, and the Rayleigh wave can be clearly shown in the waveform record.

On the basis of accurate analysis of 154 composite soil samples collected from various landscape in China and other reference information, abundance of 79 elements and composition of soils in China have been given, chemical composition of soils under the influence of matrix rock and supergenesis geochemistry condition have been studied preliminarily.

In the light of the characteristic time-frequency properties of different time-frequency analysis methods, it is

important to select an optimal time-frequency analysis method for high precision seismic exploration in the coal field on the

basis of comparing and studying these methods. Aimed at probing into STFT, Wavelet Transform, S-Transform, Choi-Williams

Distribution, Wigner-Ville Distribution and its improved methods, this paper studied advantages and disadvantages of every method

through numerical simulation in time resolution, frequency resolution and interference. The First Break Picking and Separate

Frequency Display for Collapse Column interpretation were realized by SPWVD and S-Transform, with a good result obtained.

The development of the gravity gradiometer is described simply in this paper, and the measuring principle and development experience of the rotating accelerometer gravity gradiometer are emphatically discussed. On the basis of researches on the existing airborne gravity gradiometer, the prospects of the airborne gravity gradiometer are also presented.

With the extensive adoption of computer technology in geology and geophysics, computer graphics becomes more and more important. For the purpose of improving quality and efficiency, several software should be combined in practical work. In this paper, some basic characteristics of Surfer and MapGIS are discussed, and their application in geological field is described from the angle of geological mapping, thus drawing forth the necessity of the conversion between Surfer and MapGIS. The general method and steps for the conversion of maps between Surfer and MapGIS are presented in detail, and several problems concerning the conversion and corresponding solutions are emphatically discussed.

This thesis supply a profile about performance of TerraTEM system and the  distinguishing feature of TEM. By exploring

work on two conceal iron deposit in HeNan province and analyzing. the abnormal value of the TEM system.combining with drill

drawing,The writer prove that the TEM can take a obvious effect on exploring iron mineral.

This paper has summed up the progress of the ERI method over the past decade of years as well as its future development trend in the following aspects: ① A comparison of the performances of the main ERI instruments used at present shows that the ERI instruments tend to develop in the multi-channel, multi-parameter, multi-functional, high-power direction; ② ERI measurement environment has changed from surface measurement to water surface, underwater and cross-hole measurements, with the last three kinds of measurements analyzed in this paper; ③ On the basis of analyzing ERI data processing method and inverse development status, this paper describes three-dimensional and four-dimensional inversion theory of ERI with practical examples; ④ ERT applications are summed up, and several new applications are introduced. It is concluded that, with the improvement of the probing depth and observation precision as well as the diversification of the observation models, the application field of ERI will become broader and broader, and this technique will surely have wide development prospect.

 Basic principles and techniques for the shallow seismic refraction wave method and the highdensity resistivity method

are described in this paper in combination with engineering practice to explain the results of the refraction wave method and the

high-density resistivity method in railroad and highway tunnel exploration. The application effects of the combination of these two

methods in detecting positions, sizes, natures and characteristics of such harmful geological bodies as concealed faults and shatter

zones are also discussed. Some measures for improving the investigation accuracy of these two methods are put forward.

The authors made statistic calculation of stream sediment data using such means as traditional statistics, robust estimation，cumulative percentage of 85% and multifractal statistical method in Chabaqi area and compared the thresholds obtained by the four methods. The thresholds of the same elements obtained by the four methods are obviously different from each other. The thresholds calculated by the cumulative percentage statistics are lowest except for lead, and the thresholds calculated by the other three methods fail to show obvious regularity.The results are closely related to the distribution characteristics of the geochemical data and the statistical methods used. Comparing the anomaly characteristics with the geological characteristics, the authors have found that, although weak and gentle geochemical anomalies will be mostly detected by cumulative percentage of 85%, the larger anomaly areas will bring difficulties to anomaly inspection in the field. It is therefore thought that the thresholds obtained by multifractal statistical method are suitable for the study area. A comparative study of the thresholds has led the authors to believe that the reasonable method must be combined with the actual geological conditions and based on a thorough study of the geological background of the study area.

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.

In this paper, the working principle of three satellites (CHAMP, GRACE and GOCE) has been described, and the important geopotential models and the newest geopotential models (EIGEN-CG01C, GGM02) have been introduced.

With practical examples, this paper deals with the basic principle and technique of the Rayleigh surface wave exploration, the technology for its application to railways, the data acquisition, processing and interpretation, and the calculation method for converting the velocity of the Rayleigh surface wave to the bearing capacity. The reliability of applying this technique to railways is also pointed out.

The environmental pollutant has the same lead isotope composition as its source, and hence we can determine the accurate contaminative source through the study of lead isotope composition. In recent years lead isotope tracing has been playing its unique role in studying the source and migration of heavy metals in soil. As Tl and Pb have similar geochemical characteristics, the distribution and migration of Tl in the surface soil of the Yunfu pyrite mine have good correlation with Pb. In this study, therefore, the element and lead isotope tracing was used to study the migration of thallium in soil. Element and lead isotope tracing shows that thallium pollutants are mainly accumulated in top soil of about 0-16.5 cm, and that the soil is subjected less pollution in deeper soil. The soil around the slags at the depth of some 44 cm is affected by Tl leaching from the slags.

In order to analyze characteristics of underground sources of the high accuracy magnetic data in an effective way, the

authors employed wavelet transform to make a multiscale analysis of the magnetic data. Based on the inversion and

interpretation of the plane and profile data, this paper built a geophysical model for the working area by using the 2.5D

inversion method. Tests show that the wavelet method can separate the information of different underground sources effectively

and has reliable calculation accuracy and higher resolution than traditional extension and filtering methods.

 An integrated application of such means of the intermediate gradient installment as the timedomain IP method, controlled source audiofrequency magnetotelluric sounding method and phase IP method was tested in the exploration of metallic ore deposits in the Deerbugan polymetallic ore belt in northeastern Inner Mongolia, with excellent result obtained. This test shows that the application of multiple parameters to the integrated analysis is characterized by mutual supplement and mutual verification, has abundant information, reduces the multisolution possibility in geophysical exploration and improves the reliability of geological integration.

Based on the data on the geology, minerals, exploration, and geochemistry of more than 30 fluorite deposits in the Heyu-Checun area, western Henan Province, this study summarized the types, spatial distribution, and geochemical characteristics of fluorite deposits in the area and explored the genesis and material sources of the deposits. The fluorite deposits in this area have simple types and are distributed in Yanshanian granites and along the fault zone of the external contact zone of the granites. The formation ages of the Heyu and Taishanmiao plutons are 124.7~148.2 Ma and 115~123.1 Ma, respectively. The mineralized age of fluorites is 120~126.8 Ma, indicating that the mineralization occurred in the late stage of the intrusion of the Heyu pluton and the early stage of the intrusion of the Taishanmiao pluton. The ore-forming fluids belong to the NaCl-H₂O system with a medium-low temperature, a low salinity, and a low density, indicating that the deposits in the area are medium-low-temperature supergene hydrothermal fluorite deposits. The chondrite-normalized REE patterns of fluorites in the area can be divided into slightly leftward, flat, and rightward types dominated by the rightward type. Moreover, the rightward chondrite-normalized REE patterns of fluorites are similar to those of the Yanshanian granites, both showing strongly negative Eu anomalies and weakly negative Ce anomalies. This finding indicates that the Yanshanian granites provide materials for the formation of fluorites. The metallogenic element F may mainly originate from the Heyu and Taishanmiao plutons, while the metallogenic element Ca partly comes from granites as surrounding rocks.

Due to the strong attenuation effect of loess cover on seismic and electromagnetic waves, the successful application of seismic reflection wave method and electromagnetic wave method in loess covered area is limited.In view of the characteristics of large thickness and fine stratification of loess cover, the active source and passive source surface wave methods are combined in this paper, so that the advantages of the two surface wave methods are complementary and the geological stratification of loess covered area can be accurately detected.The study area is located in the suburb of Fengxiang County,Weihe Basin.It is a typical loess covered area, and the thickness of loess cover is 80~120 m.By processing the measured data of active and passive surface waves in the study area, the positions of the main strata on the 2D shear wave velocity profile are basically consistent with the actual borehole test results, and the 3D stratum structure in the study area is also obtained.The results of joint imaging show that it is feasible and effective to use passive and active surface wave joint exploration for stratification of loess covered area, which provides technical support and beneficial idea for geological mapping of loess covered area.

This study developed a workflow of Rayleigh-wave dispersion inversion using the Python programming language, and the detail is as follows.First,carry out the forward modeling of the dispersion curves on a horizontal layered model using the pysurf96 software package.Second,create an objective function used to describe the fitting degree of the dispersion curves.Third,complete the dispersion curve inversion using the heuristic algorithm in the scikit-opt software package.The problems encountered in the function call in the workflow were proposed and solved.The results show that the Python-based dispersion curve inversion of Rayleigh wave in multilayered media is reliable and offers a certain computational efficiency.In this way,this study built a Python-based inversion platform of underground layered structures using the wave dispersion,thus providing a method for other researchers to do inversion using open-source software.Finally,this study carried out the inversion of the crust and upper mantle structures using the dispersion curves extracted from the study of Yi-bo Peng on the noise in the Hailar Basin,achieving ideal results.

The marine controlled source electromagnetic (MCSEM) method is widely used in the exploration of natural gas hydrate, seabed oil and gas resources, and seabed geological structures. In the process of marine operation, the shipborne power supply unit transmits high-voltage and high-power electric power to a marine controlled source electromagnetic transmitter on the seabed through deep towing cables, during which it is necessary to carry out the automatic and real-time measurement and monitoring of the insulation resistance in the high-voltage power supply circuit to ensure the safe transmission of electric energy and timely deal with the abnormal power supply. This study collected the leakage current between the high-pressure end and the ground using high-voltage broadband couplers, insulation detection modules, remote data transmission units, and PC monitoring software. Meanwhile, this study amplified the leakage current using an analog amplifier and then calculated the insulation resistance by measuring voltage, thus achieving the automatic measurement and monitoring of the insulation resistance between the high voltage circuit and the ground. As verified by offshore tests, the automatic online insulation monitoring technology can meet the requirements of the MCSEM system and achieve the ideal online evaluation of the insulation performance of the system, thus providing a useful reference for the research and development of similar functions of marine instruments.

The Xiong'an New Area is located in the middle part of the Jizhong Plain.The Cenozoic strata in the underground structure of the area have a large thickness,good stratification,and relatively stable tectonic activities.To finely determine the shallow geological structures,ascertain the fault structure characteristics,and improve the shallow exploration accuracy,this study combined two-dimensional seismic surveys and high-density resistivity sounding and made the following important progress.①This study finely determined the geological structure and the spatial distribution characteristics of fault structures at a depth of less than 200 m in the Xiong'an New Area;②This study constructed a three-dimensional visualized geological structure model,which intuitively displays the stratigraphic fluctuation pattern of Cenozoic strata and the spatial distribution of main fault structures;③This study analyzed and summarized the application of geophysical methods under the background of urbanization-induced high disturbance,including their exploration depths,horizontal and vertical resolution,response characteristics of geological bodies,and applicability.This study effectively supports and serves the planning,construction,and underground-space development and utilization in the Xiong'an New Area and serves as a reference for the geophysical exploration of urban underground space in hugely thick sedimentary basins.

Based on the landscape characteristics of the arid Gobi desert in the Beishan area, Gansu Province, this study carried out a 1:50,000 stream sediment survey in the Sanbaidun area and delineated 10 integrated anomalies. Then, the As-3 anomaly was preferentially selected for detail inspection by taking lithic fragments with grain sizes of 2~20 mm at multiple locations within 1/3 line spacing using a grid density of 100 m × 20 m. As a result, three integrated anomalies of lithic fragments were delineated and their characteristics were investigated. The dominant ore-forming elements were identified as As and Au, and two integrated anomalies were preferentially selected for detailed inspection using methods such as geochemical profile and trenching. Consequently, four Au orebodies, two As orebodies, one Au mineralized body, and one As mineralized body were found. The prospecting results indicate that the geochemical survey of lithic fragments can achieve ideal prospecting effects in the arid Gobi desert landscape area of Beishan and that 1:10,000 surveys of lithic fragments can be used to verify the anomalies of 1:50,000 stream sediment surveys.

Deep metal deposits tend to be associated with heterogeneous geological bodies on different scales.Moreover,their orefields mostly lie in areas with complex geological structures,developed faults,and intense lithological changes and have complex surface conditions and structures.As a result,the seismic data of metal deposits frequently originate from complex and variable seismic wave fields suffering the mutual inference of multiple types of waves.Therefore,the seismic data have extremely low signal-to-noise ratios,which severely restricts the seismic interpretation of metal deposits and the prediction of concealed orebodies. With the 2D seismic data of the Chaganhua molybdenum orefield in Inner Mongolia as a case study,this study explored the key techniques for the seismic data processing of deep metal deposits.Specifically,this study analyzed the characteristic of seismic data of the Chaganhua molybdenum deposit and summarized the difficulties with seismic data processing of the metal deposit.Based on these,this study developed a set of processes for the data processing of the Chaganhua molybdenum orefield.The actual processing results agree well with the known orebody distribution in the geological borehole section.To be specific,zones with thick ore bodies generated strong reflected energy,while thinner ore bodies exhibited low-amplitude reflected waves.The results of this study can provide strong support for inferring geological structures and delineating concealed orebodies in the study area.

The "Dongfang No.1" rock mass in the Maping area, Zhenyuan County, Guizhou is the parent rock of a primary diamond-bearing deposit discovered in China for the first time. Studies have shown that the rock mass found in the Maping area is of the shallow facies of the kimberlite magmatic system, and large-scale concealed rock pipes or buckets may exist in the deep part. To reveal the spatial distribution of deep diamond-bearing concealed rock pipes or buckets in the Maping area, this study carried out the audio-magnetotelluric (AMT) data acquisition in the area using a high grid density of 80 m × 40 m. Then it simulated the pure terrain response in the study area using the 3D forward modeling and deducted the pure terrain response from the measured data. The obtained qualitative interpretation results restored the distribution morphology of AMT impedance phase invariants to some extent that was distorted by static effects. Afterward, this study performed the 3D inversion of the data using the AR-QN quasi-Newtonian inversion method. Based on the lithologic statistical results of the study area, the resistivity variation intervals of the underground units were set during the inversion, obtaining a reliable 3D electrical structure. Finally, this study carried out a fine interpretation of the geoelectric model of this area based on geological data such as rock tubes found on the surface and multiple dikes revealed by boreholes, outlining the morphology of concealed rock pipes or buckets. This study will provide a geophysical basis for the future prospecting and prediction of primary diamond deposits in this area.

A geothermal field has been discovered in the Tianshan Sea World on the eastern margin of the Yinchuan Basin, revealing that the region has high-quality geothermal resources. The geological conditions for the formation of the geothermal field are significantly different from those of the conduction-type geothermal resources within basins, providing a new direction for the study of clean energy in the Yellow River Basin in Ningxia. This study processes and analyzes the data of 1∶50,000-scaled gravity surveys, controlled source audio-frequency magnetotellurics (CSAMT), and microtremor survey based on regional geological and geophysical characteristics. The results of the study are as follows. The uplifting zone of the Ordovician basement lies on the east side of the Lingwu Sag and spreads in an "S" shape along the Yellow River Fault. This zone reaches its highest part in the Tianshan Sea World, where it merges with the NW-trending local uplift. The Ordovician of the deep reservoirs in the geothermal field is characterized by medium-high resistance. The Carboniferous-Permian of the first cap rock at a moderate depth shows medium-low resistance and low seismic velocity. The Paleogene-Neogene of the second shallow cap rock corresponds to the formation with low resistance and low seismic velocity. Using these results, three prospective areas for developing and utilization of geothermal resources have been predicted.

To quickly and effectively detect the hidden hazards of dams,this study proposed the microtremor B-mode ultrasound technology based on linear arrays.Most of the (earth) dams also act as highways,and the vibration signals generated from running vehicles propagate along dams.Therefore,this study proposed deploying linear arrays along the dams,with the vibration propagation direction consistent with the signal receiving direction.In this way,abundant vibration sources can be provided for detecting hidden hazards of the dams.The results of this study show that the data on multiple exploration points can be simultaneously acquired using the multi-channel acquisition technique based on linear arrays,thus improving the efficiency of field data acquisition.Moreover,the influence of source differences can be avoided,and the lateral resolution and the accuracy of exploration results can be improved.The technology proposed in this study was applied to the pre-flood safety inspection of a dam in Jiujiang,Jiangxi Province.Three low-velocity hidden hazards were identified in this dam and were presumed to be the weak layers of the dam foundation and the loose media of the dam body.Practices have proved that this technology effectively counteracts the deficiencies (i.e.,low efficiency and lateral resolution) of the previous microtremor exploration.Moreover,this technology allows scanning at a spacing of 1 m or 0.5 m,thus improving the lateral resolution.This study will provide efficient and accurate guidance for dam safety management.

The primary geochemical halos, which exist in nearly all types of deposits, especially in hydrothermal deposits, serve as an essential geochemical indicator for deep prospecting. Many studies have been presently carried out on the elemental enrichment/depletion and component zoning in primary geochemical halos. However, there is a lack of reports on the spatial variations of elements and associated elements. This study collected geochemical data from 2,279 samples of the boreholes in the Zhajiatongna gold deposit and then calculated the enrichment factors and conducted a multivariate analysis to characterize the spatial variations of elements and element associations of the deposit. The element associations representing the components of surrounding rocks and mineralized components were extracted from all samples including surrounding rock samples, mineralized surrounding rock samples, and ore samples. They reflect that the deposit was formed by the superposition of mineralized components on the components of surrounding rocks in essence. Moreover, high-medium- and medium-low-temperature element associations were extracted from the ore samples, and high- and medium-low-temperature metallogenic element associations were extracted from the mineralized surrounding rock samples, indicating mineral precipitation mechanisms and the differences in the precipitation time and space. As suggested by the results, the primary geochemical halos of the Zhajiatongna deposit show the following variations from the periphery to the mineralization center: the mineralization-related elements generally exhibit an increasing trend in terms of enrichment degree and the number of enriched element types quantitatively, and the high-medium-temperature-medium-low-temperature and high-temperature-medium-low-temperature metallogenic element associations are superimposed on the surrounding rocks - mineralized element associations.

The requirements for the design and manufacturing of nodal devices are relatively low. The most basic modules of a nodal device include controllers, acquisition circuits, GNSS timing circuits, geophones, batteries, interfaces, downloading cabinets, data downloading & compositing servers, optional testing circuits, signal generators, and QC manuals. As mature supply chains are available for all the above modules, manufacturers pay more attention to organically integrating the above modules into products that can stably work and meet the needs for the signal acquisition of seismic exploration. However, the absence or neglect of some details in some products on the market due to design or cost considerations will cause difficulties in the field application of seismic data acquisition. The data acquisition quality of the nodal devices relies entirely on the independent performance and stability of each nodal device, which further rely entirely on the manufacturers’ understanding of signal acquisition for seismic exploration and data acquisition operations and the resultant design. The requirements of oil and gas exploration and development in new situations must be considered in the design of nodal devices. The focus of oil and gas exploration and development is constantly shifting to deep and ultra-deep parts with more complex ground surfaces, and thus high precision and resolution are required for signal pickup. As a result, nodal devices should be more capable of acquiring weak signals and broadband signals, which cannot be compromised in the design. This paper elaborates on the fundamental details of signal acquisition, test functions, circuit design, storage, batteries, profile, auxiliary systems, quality control, and auxiliary devices in order to avoid problems such as signal distortion, coupling, and EMC.

The main part of the Nanling Basin in Anhui Province is a red Mesozoic continental basin, under which the distribution of marine strata is still undetermined and the potential of shale gas resources is unidentified. Based on the physical property characteristics that the Permian organic-rich shale reservoirs around the study area contain pyrite, this study carried out a geological survey of shale gas using the complex resistivity method. Specifically, this study designed an observation system suitable for the different geological characteristics inside and outside the basin, conducted fitting and inversion using Cole-Brown and Cole-Cole models, and plotted maps of near-field parameters electromagnetic resistivity and apparent charging rate. The results show that: (1) The Permian organic-rich shale contains high carbonaceous content and rich pyrite particles and has distinct characteristics of low resistivity and high polarizabi-lity. Therefore, it can be effectively distinguished from its surrounding rocks, which is favorable for the shale gas exploration using the complex resistivity method; (2) Polarizability is an effective parameter that can be used to identify deep organic-rich shale strata and even shale gas reservoirs; (3) Drilling tests were carried out based on the exploration results obtained using the complex resistivity method, successfully discovering the Triassic carbonate strata and predicting that below the red basin in the Nanling Basin is the favorable area of Permian shale gas reservoirs. This study demonstrates that the complex resistivity method can detect pyrite-bearing shale strata with a depth of greater than 2,000 m and a cumulative thickness of about 200 m in the Nanling Basin and is the only method that can directly indicate shale gas reservoirs in electromagnetic exploration. Therefore, the complex resistivity method can be applied to the geophysical prospecting of the marine shale gas in the Nanling Basin with complex geological conditions and even Southern China. The results of this exploration also provide a basis for the further exploration of the marine shale gas in the Nanling Basin.

Geothermal measurement is the most direct method to study the distribution of geothermal field. The intensity and distribution of geothermal heat sources directly affect the distribution of the soil temperature field in the surface layer of the earth's crust, especially the existence of thermal reservoirs and thermal transport channels can cause anomalies in the distribution of the geothermal field. Geothermal measurements were carried out in 16 civil wells and 32 boreholes in the study area to analyze the distribution of geothermal field and the pattern of underground hot water activity, and the results were obvious.The results show that the geothermal field at shallow depths is laterally consistent with that at deep depths, with the temperature tending to increase toward the northeastern corner of the study area, and that the anomalous geothermal areas are distributed as a NNE-oriented strip, with a width of about 700 m, which is consistent with the NNE-oriented faults. The highest geothermal point is located at the intersection of the NW and NNE-trending faults.. The vertical geothermal distributions in the study area are distinct. The geothermal water is limited to a narrow area. The low-temperature groundwater inflows into the tectonic faults and karsts, with volumes controlled with the development degrees of them, leading to an abnormal geothermal gradient. This anomaly also indicated that the geothermal water in the Lasozi Mountain area is mainly stored in fissures and karst caves of limy dolomite or breccia rocks, with fissures and caves providing good pathways for the geothermal water to flow. The geothermal measurement method has traced the range of geothermal anomalies in the study area, which provides an important basis for further geothermal investigation.

Owing to the small impedance difference with surrounding rock and complex gas-water relationships,it is difficult to identify high-quality reservoirs in block S in the Sulige gas field through the post-stack P-wave impedance inversion.According to the petrophysical analysis of the study area,the pre-stack parameter v_p/v_s ratio can be used to effectively identify lithology and gas-bearing properties.This study firstly determined the seismic response characteristics of the reservoirs through forward modeling.Secondly,it conducted petrophysical modeling and the prediction of shear-wave velocities using the Xu-White model suitable for sandstone and mudstone and accordingly established a petrophysical model.Thirdly,the CRP gathers were optimized using the processing methods such as linear denoising and residual amplitude compensation.Finally,the thickness and gas-bearing properties of the reservoirs in block S in the Sulige gas field were quantitatively predicted through simultaneous pre-stack inversion.The results are as follows.(1)The top boundary of the reservoirs in the study area shows the seismic reflection characterized by strong trough reflection,while the bottom boundary of the reservoirs shows unapparent seismic reflection;(2)The v_p/v_s ratio of less than 1.68 can be used to effectively determine sandstone.This combined with the P-wave impedance of less than 12200 g·cm^-3 ·m·s^-1 can be used to predict the reservoirs in the study area. Moreover, a v_p/v_s of less than 1.57 can be used to identify the gas-bearing properties;(3)Reservoir distribution and the predicted gas-bearing range have similar trends but differ locally.The development degree of reservoirs is not necessarily positively correlated with the gas content.The method proposed in this paper is expected to provide strong technical support for delineating the favorable gas-bearing reservoir area and deploying well locations in the future.

The transparency of the fully mechanized mining face achieved using advanced exploration equipment and technology can make the information on coal seams more comprehensive and accurate and can lay a solid foundation for the intelligent production of the fully mechanized mining face. DC resistivity method is a common method for geophysical exploration. Owing to the high stability, great anti-interference performance, and sensitive responses to low- and high-resistance bodies, the DC resistivity method is one of the key means of achieving the transparency of the mining face. To explore the application effects of the method in the transparency of the mining face, this study used different working methods to conduct three-dimensional forward and inverse modeling of the response characteristics for solving proven water-bearing structures of the mining face and frontal advanced detection of roadways. The results show that the distribution laws of 3D DC inversion data obtained by corresponding working methods were basically consistent with those of the initial model, and the DC resistivity method can well distinguish between high- and low-resistivity bodies. Therefore, this study can guide the application of the DC resistivity method in the transparency of mining face in practical engineering.

In recent years, prospecting in coverage areas has become an important topic in China due to the strong demand for energy and mineral resources, and there is an urgent need for new targeted methods and technologies of prospecting. This study put forward a technology system for the collaborative and rapid prospecting of copper-nickel deposits in coverage areas that combines airborne-ground-borehole prospecting methods and technologies. Meanwhile, this study established the framework and description of the collaborative, rapid, and effective exploration technology system. Taking the terrain and geology of coverage areas, as well as the distribution characteristics of deep mineral resources in the area as preconditions, this technology system mainly uses the methods of aero geophysics combined with ground and borehole geophysical exploration and focuses on big data fusion, weak information extraction, and geophysical-geological modeling methods. Meanwhile, it takes geological structure and metallogenic theory as guidance. This technical system has been verified in the exploration of the concealed magmatic copper-nickel deposit in the Qixin area, Ruoqiang County, Xinjiang, achieving positive results.

This study investigates the geochemical characteristics and genesis of selenium (Se) in the soil in Xuancheng City, Anhui Province using the samples of surface and deep soil collected through a 1:250 000 multi-purpose geochemical survey. The results are as follows. The Se content in the surface soil in Xuancheng City is (0.12~8.80)×10^-6, with an average of 0.44×10^-6. Se-sufficient and Se-rich soils are widely distributed in the study area, accounting for 61.90% and 35.63%, respectively. Se-rich soils are mainly distributed in the Ningdun Town in Ningguo City-Fulingtown in Jixi County, Yangong Town in Jingxian County-Baikeshu area in Xuanzhou District, Chencun Village-Chikeng Mountain in Jingxian County, and Xinhang Town in Guangde County. The Se content in the soil is mainly controlled by parent rocks and soil-forming parent materials. Se content is high in soils in the distribution areas of carbonaceous shale and carbonaceous siliceous mudstones, such as the SinianLantian Formation and Cambrian Hetang and Yangliugang formations, as well as Permian, Triassic, Carboniferous, Cambrian, and Ordovician limestone distribution area. In contrast, Se content is low in Yanshanian intermediate-acid intrusive rocks and Quaternary distribution area. In terms of soil-forming parent materials, Se content is higher in soils with parent materials of carbonate, light clastic rocks, and epimetamorphic rocks than that in soils with parent materials of Late Pleistocene loess, alluvium, and acid rocks. In terms of soil type, Se content is higher in limestone soil, skeleton soil, stonysoil, and red soil than paddy soil, yellow-cinnamon soil, and fluvo-aquic soil. Se content in soil is correlated closely with physicochemical indices, such as V, Cd, Ba, Ag, Zn, Mo, U, Ni, Sb, P, S, and organic matter. Meanwhile, total Se content is correlated closely with bioavailable Se content. Furthermore, all the 47 rice samples collected in the study area are rich in selenium, with a selenium accumulation rate of 100%. However, tea and maize are not rich in Se, and some types of vegetables are rich in Se. Therefore, different types of crops have different absorption capacities of Se in the soil.

Gold deposits of the quartz-vein-type are the product of post-magmatic hydrothermal and metamorphic hydrothermal processes and are generally controlled by major and secondary faults. Their metallogenic materials originate from the surrounding rocks. The assemblages and contents of metal sulfides in ores of various deposits differ with geological setting and ore-forming and controlling conditions. Moreover, sulfide-gold-quartz ores predominate. The gold deposits of this type have distinct comprehensive geophysical prospecting features, and various physical prospecting methods yield a high degree of regularity. Taking a gold deposit of the quartz-vein-type in northwest China as an example, this study carried out comprehensive physical prospecting of deposits of this type, performed a quantitative prediction based on forward modeling, and conducted interpretation and analysis by combining theories related to geophysical prospecting.

An ocean bottom electromagnetic receiver (OBEM) is primarily designed to measure the submarine electromagnetic signal. In order to verify the function of the instrument and improve the accuracy of result, the instrument is self-checked by a built-in channel calibration before OBEM enters the water. OBME-Ⅲ needs to export the calibration file generated by channel calibration from the instrument, and then use the Matlab program on the PC side to perform calibration calculation, which has shortcomings such as complex offshore operations and low calculation efficiency. In order to solve these problems, the author developed a calibration calculation program based on the ARM-Linux platform. By entering the relevant commands, the channel calibration calculation can be realized locally in OBEM-Ⅲ, reducing the trouble of exporting data for calculation on multiple platforms. The mixed-base fast Fourier transform calculation method adopted reduces the calculation time from 90 s to 11 s while ensuring the calculation accuracy, which greatly improves the calculation speed and improves the efficiency of the instrument's offshore operations. In the magnetotelluric scientific research mission carried out in the southwest of the South China Sea from July to August 2020, the program performed well and successfully obtained high-quality submarine magnetotelluric sounding data.

In the process of hydraulic fracturing for shale gas extraction, the injection, flowback, retention, and absorption of fracturing fluids will cause changes in electric fields in the case of the excitation by the electromagnetic field from an artificial source in a far area or the excitation by the geoelectric field. The time-dependent change in the information on fracturing can be reflected by monitoring the change in weak electric fields above the hydraulic fracturing area. To meet the needs of the real-time monitoring of the fracturing field, this study focuses on the preliminary study of the monitoring technology based on the nodal acquisition devices of distributed weak electric fields. The monitoring system only collects two horizontally orthogonal electric field signals, monitors the real-time information on the electric field within a certain range, and transmits the preliminarily processed data back to the data center in a wireless way. Test results show that the monitoring system has stable performance, a standby time of more than 10 days, and high sealing performance, and is applicable to complex field environments. Therefore, this monitoring system can provide important technical support for obtaining images of fracturing fluid migration in the future.

The distortion correction of magnetotelluric sounding curves is critical to magnetotelluric exploration. Based on the comparison between the resistivity logging curves of basin D and the basin's inversed sounding curves before and after being corrected through magnetotelluric sounding translation, this study constructed a transformation function and calibrated magnetotelluric sounding curves using logging curves. The magnetotelluric inversion results improved using the calibration technology proposed in this study are highly consistent with the verification boreholes. Finally, this study effectively revealed the structural characteristics of basin D by combining drilling, seismic, gravitational, and magnetic data.

This study aims to eliminate the electromagnetic coupling interference in IP sounding. Based on the theory that frequency-and time-domain data can be mutually converted, this study achieved rapid decoupling while retaining the IP information to the greatest extent by using decoupling methods including static IP inversion, the full waveform IP inversion of Cole-Cole parameters, and delay inversion. This study investigated a gold deposit in Yinan County, Shandong Province and conducted the inversion of time-domain IP sounding data before and after decoupling. The results are as follows. The electromagnetic coupling effect of symmetrical quadrupole devices and unconventional electrode array increases with an increase in the distance between adjacent electrodes, and its influencing depth is mostly less than 150 m in the inversion results of time-domain IP sounding; the electromagnetic coupling interference produced by the unconventional electrode array that adopts a collinear device of dislocation multipoles (tripoles, quadrupoles, and dipoles) is apparently greater than that of symmetrical quadrupole devices and monopole-dipole devices; noncollinear monopole-dipole devices generate slight electromagnetic coupling effect in the process of time-domain IP sounding.

The mineralization of deposits of rare metals such as tantalum and niobium in China is mostly related to granite pegmatite. The enrichment of rare metals in these deposits is accompanied by the formation of radioactive minerals, such as albite, monazite, and high-grade uranium, and these deposits have paragenetic and associated minerals uranium deposits. Therefore, radioactive prospecting has become the most convenient and effective method to explore deposits of rare metals such as REEs, Nb, and Ta. Based on the close correlation between mineralization and radioactivity of rare earth minerals, this study fully investigated the parameter characteristics of the surveyed energy spectrum data through the combination of airborne radioactivity measurement and ground gamma spectrometry measurement to determine prospecting indicators. A new niobium-tantalum-rubidium polymetallic mineralized point was discovered in the Nancha area, Yichun City using the radioactive prospecting method, which was thus proven effective.

In the shallow or mine prospecting using the transient electromagnetic method (TEM), the transmitting magnetic moment is limited by the limited supply voltage of the transmitting system, and the stray inductance of the transmitter loop causes a long turn-off time. To solve these problems, this study designed a parallel transmitter loop of ultra-small coils used in TEM. Using these coils, the transmitting magnetic moment can be increased by the parallel connection of the coils, and the turn-off time can be reduced by additional resistance. The equivalent circuit models of the conventional transmitter coils and the parallel transmitter coils were established and analyzed theoretically. Moreover, the comparative test between the parallel transmitter coils and the conventional transmitter coils were carried out. The results show that the parallel transmitter coils can effectively increase the magnetic moment and reduce the turn-off time. Therefore, this design is greatly significant for reducing the blind area and increasing the prospecting depth in shallow or mine prospecting using TEM.

Ocean electric field signals are widely used in the fields of geological tectonics, water target detection, physical ocean, and the analysis of ocean physical characteristics. It is of great scientific value to collect the ocean electric field signals, while the ocean electric field is measured using ocean electric field sensors. In recent years, perovskite-type composite oxides have become a research hot spot as new materials. Among these composite oxides, SmNiO₃ is the one that possesses some unique properties including metal-insulator phase transition, strong stability in seawater, and high sensitivity to low-frequency electric field signals. Therefore, it is expected to become a new type of electrode materials in ocean electric field sensors. Domestic and foreign researchers have carried out some studies on SmNiO₃, which mainly focus on the electrical properties (especially the metal-insulator phase transition and optical properties) and preparation process of SmNiO₃. This paper systematically reviews the above research contents and preliminarily explores the feasibility of applying SmNiO₃ in marine electric field sensors.

The computational efficiency of the forward modeling for gravity and gravity gradient anomalies determines the feasibility of inverse modeling. It also forms the basis for the efficient building of sufficient and diverse deep learning sample data. Inspired by the application of moving-footprint—a fast forward modeling method in the aerospace electromagnetic field and based on the fast space-domain forward modeling of geometric lattice functions of grid points, the authors proposed a computation method for the forward modeling of gravity and gravity gradient anomalies by applying “moving-footprint”, aiming to further improve the speed of the forward calculation for gravity and gravity gradient anomalies. Specifically, this method selects the subspace in a certain effective range directly below an observation point in the underground half-space. The observation point anomaly approximates the total anomalies of the cuboid units in the corresponding subspace while ignoring the anomalies produced by the cuboid units outside the subspace. When the observation point moves, the corresponding subspace moves accordingly. Therefore, the large-scale underground half-space cuboid model can be decomposed into the subspace corresponding to each calculation point for the forward calculation. As shown by the results of a model test, when 32×32×15 subspace was selected in the underground half-space of a 256×256×15 rectangular parallelepiped model for calculation, the relative average error of gravity anomalies and partial gradient anomalies was less than 10% and the calculation speed was increased by 19 times. Moreover, the calculation time of 1024×1024×15 rectangular parallelepiped model is approximately 32 minutes. Compared with the existing algorithms with a bottleneck in the ultra-conventional calculations, the method proposed in this study has significant advantages regarding computation.

Ocean bottom electromagnetic receivers (OBEMs) are mainly used for high-precision observation and measurement of magnetotelluric signals and controlled-source electromagnetic signals at the sea bottom. To overcome the shortcomings of large volume, high power consumption, and high cost of the existing OBEMs (OBEM-Ⅲ type), this study conducted technical research regarding miniaturization, low power consumption, and low cost. As a result, the overall power consumption of the existing OBEMs (OBEM-Ⅲ type) has been reduced from 1 600 mW to 500 mW or less (by equipment of inductive magnetic sensors) due to the development of a low-power control unit and preamplifier, the installation of low-power fluxgate sensors, and adoption of advanced power management technology. Traditional acoustic releasers are expensive and bulky and require more suitable buoyant materials. By integrating the underwater acoustic communication module and being equipped with the external erosion wearing release device, the MicrOBEMs make release and recovery possible using only a 17-inch glass sphere, thus greatly reducing the volume and hardware cost of the instrument and improving the integration and operation efficiency of devices. Compared to the OBEM-Ⅲ type, the volume, power consumption, and cost of the newly developed MicrOBEMs are reduced by 3/4, 2/3, and 1/2, respectively. A deep-water geomagnetic test was conducted in March 2021 in the southern South China Sea, preliminarily verifying the geomagnetic measurement function of the MicrOBEMs and reflecting that the MicrOBEMs have the advantages of small size, low power consumption, and low cost.

There are many small coal mine goaves in Huazi Town-Xidayao Town in Dengta City, Liaoyang City, Liaoning Province. They are distributed in villages and towns and their surrounding areas, posing great threats to the ground buildings and resident life. Furthermore, the vegetation around the mining area is sparse, and a large amount of coal slag has been piled up at will, which causes serious damage to the ecological environment. However, owing to the limitations of a single geophysical method, it is difficult to completely eliminate interference and observation errors through the goaf investigation using a single geophysical method. Based on the selection and exploration of geophysical methods from the aspects of anti-interference and effectiveness, this study conducted the coal mine goaves in the study area by applying the geophysical prospecting methods including gravity survey, high-density resistivity method, and shallow seismic reflection method. As verified through drilling, ideal results were achieved.

Anning City, Yunnan Province, China is an important area of economic development and ecological civilization construction in central Yunnan on the upper reaches of the Yangtze River. This study investigated the contents and enrichment degrees of elements including heavy metals in the surface soil samples that were systematically collected in the Anning area from 2018 to 2020. Then, this study assessed the ecological risks of heavy metals in the soil using the geoaccumulation index and the assessment indices of potential ecological risks and analyzed the sources of heavy metals using the methods of the Pearson correlation and principal component analysis. The results show that heavy metals Cr, Zn, As, Cd, Pb, Hg, and radioactive element U in the soil in the study area have significantly higher contents than corresponding background values of soil in Yunnan Province and show high-degree variation and uneven spatial distribution. Moreover, Cr has the highest accumulation degree of geological anomalies, elements As, Cd, and Hg have high potential ecological risks, and ecological risks are mainly concentrated in the phosphate mining area and the vicinity of steel plants and chemical plants in the Tanglangchuan basin. In terms of sources, Cr, Ni, and Cu may mainly originate from soil parent materials; areas with high Cd, Pb, Zn, and As contents are significantly affected by human activities, and Hg may have a composite pollution source. These results will provide a scientific basis for understanding the sources of heavy metals in soil in Anning City and for the management and protection of local land resources.

An application test of the broadband magnetotelluric method (BMT) was carried out in the Mandulatu area based on the construction needs of a large-scale sandstone-type uranium deposit base in the Erlian Basin. The purpose is to study the detection ability and effect of this method at a depth of 2,000 m and above, provide effective technical support for the evaluation of uranium resources in the area, and improve the effects and benefits of uranium prospecting. In this study, the data acquisition time and the lowest frequency were tested by the test area method. Given the work efficiency and benefit, it is determined that the lowest detection frequency is 0.10 Hz and the observation time is 60 min so that the prospecting depth of Erlian Basin can reach the requirement of 1,500~2,000 m. The comparative analysis of the test results with borehole and shallow seismic data shows that BMT is feasible in solving geological problems such as caprock structure, basement structure, sand body development characteristics of the target layer, and fault structure in the basin.

The Weiquan silver-copper polymetallic deposit has received extensive attention because of its unique genesis. This study analyzed the anomaly characteristics shown in the integrated gravity-magnetic-electrical geophysical planes and sections of the Weiquan silver-copper polymetallic deposit. Then, it obtained the interpretation model of geophysical anomalies through the forward and inverse calculations of the typical sections. Based on the distribution pattern of existing ore bodies and the metallogenic model summarized in previous studies, this study established the geological-geophysical prospecting mode of this area. Moreover, this study proposed the geological-geophysical prospecting model of this area, aiming to provide a basis for prospecting prediction.

With the advantages of flexible configuration,convenience,high efficiency,and resolution,the single-channel seismic detection technology has been widely used in marine geological surveys and offshore engineering geophysical prospecting.However,there are few cases of the application of this technology in inland rivers and lakes.Therefore,an experimental study on the high-resolution single-channel seismic detection technology targeting the inland shallow waters of Baiyangdian Lake,Xiongan New Area,Hebei Province was conducted.The application effects using key acquisition parameters,including excitation energy,excitation interval,sailing speed,and the number of receiving units,were compared to determine the optimal parameter combination.A set of single-channel seismic data processing processes and methods for inland shallow waters were developed to gradually attenuate all kinds of noises and improve the signal-to-noise ratio and resolution to the greatest extent.The experimental results show that the single-channel seismic detection technology for inland shallow waters can finely divide the shallow stratigraphic structure in the waters.Moreover,the division effects agree well with drilling data.Therefore,this technology can effectively support the investigations of environment,geology,and geologic hazards in inland rivers and lakes.

Karst is widely distributed in China. However, geological disasters frequently occur in karst zones due to the fragile geological environment, which seriously threatens the safety of people’s life and property and cause huge economic losses. In this study, the controlled source audio-frequency magnetotelluric (CSAMT) method and microgravity were used to extract residual gravity anomalies through the two-dimensional inversion of pseudosections and multi-scale wavelet analysis. As a result, rock-soil interfaces of karst zones and the development zones of strong karst were well divided; the locations, burial depths, scales, and spatial distribution of karst caves were delineated. As verified by drilling, the rock-soil interfaces and strong-karst development zones determined by CSAMT interpretation were roughly consistent with those revealed by boreholes, and the sizes and burial depths of collapsed karst caves that were delineated by microgravity roughly correspond to those revealed by boreholes of engineering exploration. These results show that the CSAMT combined with the microgravity method can achieve significant effects in the detection of concealed karst collapses and serves as a scientific detection method for the early warning of the prevention and treatment of potential karst collapses and similar geological disasters.

The drilling engineering for shale gas in carbonate areas in China is facing prominent carbonate karst. It is necessary to carry out near-surface geophysical prospecting before drilling and reasonably select the well locations in order to ensure the safety of the well site and reduce the drilling engineering risks. Taking the siting of Well Guirongye-1 in Rong'an County, Liuzhou City, Guangxi Province as an example, this study conducted the application research of well siting before drilling comprehensively using three geophysical prospecting methods, namely the high-density resistivity method, the audio-frequency magnetotellurics method, and radon survey, achieving satisfactory results. Well Guirongye-1 did not encounter a fault fracture zone near the surface, which is basically consistent with the interpretation results of comprehensive geophysical prospecting. This result indicates that the comprehensive geophysical prospecting method is feasible and effective in the siting of shale gas exploration wells in the carbonate areas in south China. This study will provide a certain reference for the well siting before drilling in similar areas in the future.

Multi-scale wavelet decomposition is one of the common methods for gravity potential field separation. The biggest advantage is that it breaks through the traditional concept of dichotomy gravity anomalies and achieves the multiple decomposition of gravity anomalies. However, no systematic study has been carried out on the limitations and properties of the multi-scale wavelet decomposition. To systematically investigate the multi-scale wavelet decomposition and provide guidance for its practical application, this study, starting from the definition of multi-scale wavelet decomposition of gravity potential field based on profiles and grids, expounded three important properties such as the criterion that low-order wavelet keeps details invariant. Then, it analyzed the definition and properties of multi-scale wavelet by designing simple and complex theoretical models. Afterward, this study compared the multi-scale wavelet decomposition with the interpolation cutting method using field data. The results show that multi-scale wavelet decomposition can achieve multi-layer separation of gravity potential field and estimate the burial depths of source bodies. In addition, the multi-scale wavelet decomposition can provide some ideas for solving the limitations pointed out in this study, such as abnormal scale aliasing and difficulty with the determination of scale coefficients. The above basic research can provide a certain degree of references for the processing and interpretation of gravitational potential field data.

The special topographic and geomorphic conditions in the desert exploration area of the Guaizihu sag in the Yin'e Basin produce adverse effects on the excitation and reception of seismic data.The surface of the area is covered by hugely thick loose sand,with the thickness of the sand dunes varying in the range of 50~100 m.In the process of vibroseis data acquisition in this area,"black triangle" noise is formed in the near-trace scope due to the dual effects of the mechanical characteristics of the vibroseis and the near-surface structure,resulting in a low signal-to-noise ratio of seismic records.Since the "black triangle" noise features high energy,wide frequency range,wide distribution,and great morphological difference,it is difficult to make accurate statistics of its amplitude (intensity) in a single arrangement of the common shot domain and the common receiver domain,thus resulting in too much residual noise after the suppression of the "black triangle" noise.Given this,this paper proposes a method,in which data rearrangement is firstly conducted based on the shot-offset domain and then denoising is performed.As verified by the application of actual vibroseis data of the Guaizihu area in the Yin'e Basin,this method can effectively protect the near-trace reflection signals(especially the deep weak reflection information) while effectively suppressing the "black triangle" noise and it is effective in improving the signal-to-noise ratio of seismic data.

The acid-base properties and Se background values of the soil in Qinghai Province were obtained by analyzing the pH and Se content of the soil based on the data derived from the geochemical survey of land quality conducted in Qinghai Province. The Se enrichment models of root soil and crops such as wheat, rapeseed, pea, garlic, and forage were established accordingly. The recommended values of Se-rich soil in Qinghai were calculated by combining the recommended in take of Se in the population with the standard value of Se content in Se-rich agricultural and livestock products in Qinghai Province. It is recommended that the lower limit of Se-rich soil for alkaline soil and neutral and acidic soil in Qinghai Province should be 0.23×10^-6 and 0.25×10^-6, respectively. This study is greatly significant for the formulation of the local standards for Se-rich soil in Qinghai Province and for guiding the development of the selenium industry.

Regarding the genesis of the geothermal resources in Guizhou Province, most researchers tend to think that the geothermal resources were formed from the temperature rise induced by the mechanical energy of the “geothermal gradient” controlled by seismic activities and faults and that the geothermal resources do not possess from magma heat sources nor have the conditions of radioactive heat generation. Based on the research on the previous achievements, the characteristics of geothermal reservoirs and cap rocks, and regional gravity and magnetic data, the inference of the deep faults and intermediate-acid and basic-ultrabasic rock masses, and the analysis of regional distribution characteristics of natural geothermal resources and geothermal wells, this study proposes two possible basic genetic models of the geothermal resources in Guizhou. One is that automatic temperature rise and cyclic heat generation caused by the “geothermal gradient” controlled by deep faults. The groundwater with continuous temperature rise driven by this model is the most developed. The other genesis is the waste heat of magmatic rocks. It is inferred as a new type of heat generation and genesis supplement. As an important regional metallogenic region of uranium and thorium in China, Guizhou Province has only been researched at a low level and on a small scale, with a small amount of available data. Therefore, it is not clear whether there are basic conditions of radioactive heat generation in Guizhou Province. The in-depth study on the genesis of geothermal resources can provide relevant bases for the accurate surveys of geothermal resources and the expansion of prospecting direction in Guizhou Province in the future.

Owing to geographical factors and historical reasons,the urban underground square cavities show increasing number,density,and chaotic state,leading to unclear interpretation results of the ground penetrating radar(GPR) images of these underground square cavities.This study divided the left side of an image(with the symmetry axis as a boundary) of square cavities obtained from the GPR scanning close to the ground into three stages based on the whole process of ground penetrating radar scanning detection.Then,this study established the relationships between horizontal distance and echo delay of each stage.Furthermore,it systematically analyzed the changes in the GPR images of square cavities with different burial depths and sizes.Finally,this study obtained the scientific explanation of geological radar imaging mechanisms of underground square cavities based on GPR detection examples.It is concluded that the three stages of the left side of a GPR scanning image of the underground square cavities in uniform media include a continuous straight line with a constant slope,a monotonically decreasing continuous concave curve,and a continuous horizontal straight line unrelated to the horizontal distance.With an increase in the burial depth and cavity size,the curve tends to be gentle and its open radian tends to increase.

This study aims to investigate the characteristics, pollution sources, and ecological risks of heavy metals in the stream sediments in Heze City, which is an important catchment area in the east route of the South-to-North Water Diversion Project. To this end, stream sediment samples were collected from 25 sites of three major river basins in Heze City, and the contents of Cu, Zn, Ni, Cr, Cd, and Pb in the samples were analyzed. Moreover, this study assessed the ecological risks of these heavy metal elements using the pollution load index (PLI), potential ecological risk index (RI), and logarithmic regression model and determined the pollution sources of these heavy metal elements through correlation and principal component analysis. The results are as follows. The contents of the six heavy metal elements in the stream sediment samples were generally higher than their background values. The Ni and Cd contents at all investigated sites exceeded their background values, especially the Cd content at 40% of the investigated sites, which was more than three times the background value. The heavy metals in the stream sediments of the three river basins are unevenly distributed. The maximum values of the six heavy metals all originated from the samples of the Zhuzhaoxin River basin, of which the PLI, RI, and toxicity ratio Y were 1.67, 123 and 0.367, respectively. These values were higher than those of the other two basins, indicating that the heavy metals in sediments of the Zhuzhaoxin River basin reach moderate pollution and have high ecological risks and potential harm to aquatic organisms. The principal component analysis shows that the petroleum refining and related chemical enterprises in industrial parks are the main contributors to the enrichment of the six heavy metal elements.

The Laowan area in Henan Province is an important gold minerogenetic area in the Tongbai-Dabie noble nonferrous metal metallogenic belt. Based on the comprehensive analysis of the metallogenic factors of the area, the authors extracted and established nine predictive variables, i.e., strata, ductile shear zones, brittle fault zones, magmatic rocks, gold-related alteration zones, and single-element anomalies of gold, arsenic, antimony, and sliver in stream sediments. Then, the authors predicted metallogenic prospect areas of gold in this area using the weight of evidence model and the MRAS software. Grid cells with a size of 0.10 km×0.10 km were used for prediction, and they were divided into classes A, B, and C in terms of prospecting prediction through the prior probability calculation, weight statistics, independence tests, and posterior probability calculation of each prediction variable. Based on the distribution characteristics of various classes of prediction grid cells and the geological characteristics of gold deposits in the study area, this study delineated four first- and four second-order prospecting target areas. According to comprehensive analysis, most of the known gold deposits or gold ore occurrences fall into the prediction blocks of classes A and B and the prediction blocks of class C lie around the prediction blocks of classes A or B. This analytical result is consistent with the gradual changes of the metallogenic belt from the center to the edges. Gold deposits or ore occurrences have been discovered in all the delineated first-order prospecting target areas, and the posterior probabilities have a high average. Therefore, first-order prospecting target areas have great gold prospecting potential.

The Pengshui area,located in the Wuling fold belt at the southeast margin of Sichuan Basin,has a typical karst mountain landform and very complex near-surface structures.Such a geological setting leads to a poor seismic acquisition effect and a low signal to noise ratio (SNR),which seriously affects the oil and gas exploration in this area.This study carried out the excitation tests and research,such as charge type,excitation mode,excitation well depth,and excitation dose,as well as receiving tests on interference wave investigation and geophone types and their combination means on the ground surface in the mountainous areas with exposed carbonate rocks.Furthermore,this study selected a set of excitation and receiving parameters with a strong economy and maneuverability and established the technology used to determine the optimal excitation point location for complex mountainous terrain.Compared with the previous data,this study achieved significantly improved energy,SNR,and first-grade product rate of the newly acquired single-shot records.Moreover,the new data processing profiles obtained in this study show rich information,clear reflection characteristics,and high SNR and display a distinct seismic tectonic pattern of carbonate rock area.

Since a large amount of domestic and industrial wastewater containing heavy metals has been discharged into the Haihe River Basin, many heavy metals enter the water environment and accumulate in the sediments. Traditional ecological risk assessment methods ignore the speciation and distribution of heavy metals, leading to the low reliability of ecological risk assessment. This study investigated the plain section of the Haihe River Basin and researched the speciation and distribution of heavy metals in the sediments in the Haihe River Basin and carried out the ecological risk assessment. Sediment samples were collected at the collection points deployed in the Haihe River Basin. Afterward, the samples were processed using mixed acids at the laboratory. Then, the contents of heavy metals in the samples were determined using atomic absorption spectrometry, and the speciation and distribution of heavy metals in the sediments were analyzed. For the ecological risk assessment, abundance calculation was adopted to improve the ecological risk assessment indices and design the ecological risk assessment standard of heavy metals. The experimental results show that the obtained evaluation of the sampling points and various heavy metals were closer to the actual situation, has higher reliability, and displayed better evaluation performance compared to results obtained using traditional assessment methods.

To overcome the shortcomings of traditional nonpolarizing electrodes, such as the poor stability of potential difference, high low-frequency noise, short life, and requiring regular maintenance, the authors researched and developed maintenance-free ultra-low noise Pb-PbCl₂ nonpolarizing electrodes after over a decade of development and constant tests. Lab test results show that the new nonpolarizing electrodes have a potential difference drift within one month of less than ±0.06 mV and a temperature coefficient of less than 20 μV/℃, which are 5% and less than one-fifth of those of the PMS9000 electrodes exported from France, respectively; under the ideal condition of the distance between two adjacent electrodes of 100 m, the signal-to-noise ratios relative to the natural induced electric field are 40dB@10³s, 20dB@10⁴s, and 10dB@10⁵s. The field comparative tests show that the newly developed solid nonpolarizing electrodes can significantly improve the acquisition accuracy of geoelectric field signals and the data quality of dead and low magnetotelluric frequency bands.

Surface soil samples in Yaling Town, Yichuan County -Xiaodian Town, Ruyang County in Luoyang City were collected and analyzed to study the selenium (Se) speciation and its influencing factors. The study results are as follows. Existing Se in the surface soil of the study area mainly occurs in humic acid, residue, and strong organic states, while the sum of Se in water-soluble and ion-exchange states only accounts for 2.70% of total Se in the surface soil. Therefore, the Se in the study area shows the characteristics of the low content of water-soluble Se and a significantly high proportion of organic Se in total Se. The Se speciation in the surface soil is affected by the total Se content, pH, organic matter content, and type of soil. Specifically, the proportion of bioavailable Se in alkaline soil is significantly higher than that in neutral and acidic soils, and the bioavailable selenium content increases with increasing soil pH. Especially, the organic matter content in the soil has the most significant effects on organic Se but has no significant effect on bioavailable Se. For different types of soils, the proportion of the sum of Se in water-soluble and ionic-exchange states in total Se is in the order of red clay>paddy soil>brown soil>skeleton soil>fluvo-aquic soil>lime concretion black soil.

This study selected the Jinsha Lake and the Miersi Industry Park as key survey areas to study the distribution of heavy metals in soil in Hong’an County, Hubei Province. Samples were collected from surface soil and vertical soil profiles to assay the contents of eight heavy metals, i.e., Cu, Pb, Zn, Cr, Ni, Cd, As, and Hg. Both the single factor pollution index method and the potential ecological hazard index method were used to assess the distribution and the ecological risk of heavy metals. The study results are as follows:The average contents of the above eight heavy metals were 21.48×10^-6, 21.75×10^-6, 63.60×10^-6, 53.24×10^-6, 20.25×10^-6, 0.13×10^-6, 5.44×10^-6, and 0.04×10^-6,respectively. The cumulative Cu, Cr, Ni, and Cd are relatively enriched in the soil and their pollution is slight. The heavy metals show distinct distribution patterns. Minor pollution exists in the Gaoqiao-Yongjiahe basic-ultrabasic melange zone and around the Miershi Industrial Park, while severe pollution exists in Mn-Co mineralized points scattered in the northeastern Baliwan. Pb and Hg are enriched in the surface layer but decrease in the deep layer, Cr and Ni show an inverse trend, while other elements show indistinct distribution patterns. Cd and Hg have high potential ecological risk individually in the soil in the surveyed areas. The comprehensive ecological risk assessment based on Cd and Hg shows that the surrounding area of the Jinsha Lake Chengguan Town, the basic-ultrabasic melange zone, the surrounding area of the Miersi Industrial Park, and the Baliwan manganese-cobalt mineralization zone are areas with moderate potential ecological risks, where ecological supervision and protection should be strengthened. This study can provide a scientific basis for later ecological management in Hongan. It also serves as a good soil reference for other ecological geological surveys.

Plane beam signals form when multiple excitation sources simultaneously emit pulses with the same center frequency (multiple-source concurrency),thus enhancing the quality of data records.This paper compares and analyzes the electromagnetic wave absorption effects of unsplit recursive convolutional perfectly matched layer (PML) as the absorbing boundary condition and Mur second-order absorbing boundary condition under multi-source concurrency through numerical simulation.According to study results,the traditional Mur second-order absorbing boundary condition did not perform well in absorbing electromagnetic waves under the conditions of multi-source concurrency and multi-angle grazing,and it will cause waveform distortion and spurious reflections in the case of large offsets.For the unsplit recursive convolutional perfectly matched layer as the absorbing boundary condition under multi-source concurrency,coordinate scale factors were introduced into the finite-difference time-domain (FDTD) algorithm.Then,the PML equation for coordinate stretching was transformed from frequency domain into time domain through the inverse Fourier transform.Finally,the electric and magnetic field values were solved using the recursive convolution method in the discrete state,thus avoiding the complicated calculation involved in directly determining the numerical solution of convolution.This allows less memory space and high calculation efficiency while ensuring accuracy.Therefore,the unsplit recursive convolutional perfectly matched layer method improves the electromagnetic wave absorption effect at the positions where the grid terminate without inducing wave-field splitting.

Full waveform inversion (FWI) is one of the most accurate velocity inversion tools.It can be used to obtain high-precision subsurface structures through iterative inversion and provide a more accurate velocity field for prestack imaging technology,thus satisfying the increasingly complex demand for petroleum exploration and development.However,FWI requires accurately estimated source wavelets,which are very difficult to extract from the seismic data collected in the field.Furthermore,in the inversion process,there is a strong nonlinear relationship between model parameters and observed data,which is liable to induce cycle skipping.To overcome the cycle skipping and the difficulty in extracting seismic wavelets in the inversion process of medium-low wavenumber,this paper developed a multi-scale waveform inversion method using combined source encoding.Specifically,the wavelets and seismic data were combined by applying time-shift stacking,and gradients can be determined through only one calculation of reverse time migration.According to the calculation results using a model,the FWI method using combined source encoding can be used to achieve multi-scale inversion and obtain more stable inversion results.Meanwhile,relatively accurate inversion results can be obtained by combining this method with a source-independent method.

This paper summarizes the current status and progress of major system integration technologies for airborne geophysical prospecting used abroad from 2015 to 2020. During this period, some old systems were improved, while some became obsolete. Meanwhile, new system integration methods constantly emerged during this period. Specifically, towed birds using geomagnetic gradient began to be widely applied. At the same time, with the significant improvement of flight control and load capacity, UAVs were widely applied in magnetic, electromagnetic, gravity, and gamma-ray spectrometry fields. SQUID magnetic tensor gradiometers and FTG gravity tensor gradiometers were successively put into commercial airborne geophysical prospecting. The signal-to-noise ratio of electromagnetic systems was significantly improved, and CsI (Tl) scintillators were preferred by companies producing gamma-ray spectrometry instruments.