Grounded-source transient electromagnetic method (TEM) has many advantages such as deep exploration, flexible arrangement in rough terrain and high working efficiency. Recently it has got much attention and a series of new methods are available, ranging from surface to airborne and borehole method. In this paper, the authors review the research history of long-offset TEM (LOTEM), short-offset TEM (SOTEM), multi-channel TEM(MTEM), grounded-source semi-airborne TEM and grounded-source surface to borehole TEM, and summarize their research status in forward modeling, system design, inversion, imaging and field working. The results show that, as a well-developed grounded-source TEM, LOTEM has accumulated many research achievements. Although some progress has been made, the researches on other grounded-source TEMs are still in a primary stage and still need further improvement. Valuable research results in LOTEM, for example, noise suppression technology, high dimensional inversion and point interpretation, can be introduced to these newly developed electromagnetic methods, which can help provide solutions for high working efficiency and high resolution deep exploration.

Dual-Probe Heat-Pulse method was modified for application of determining in-situ thermal conductivity of marine

sediments. It was crucial to process DPHP data and extract thermal conductivity from these data. A processing flow was

established based on measured data with consideration of the specific measurement situations at sea. The pre-processing

procedure, including filtering, trimming, and ambient temperature fitting and eliminating, was suggested in order to obtain a

temperature response curve of heat pulse, which was then utilized to calculate thermal conductivity. Besides the K-B model, a

simplified model to calculate thermal conductivity was advanced which has advantage in reducing operation and cumulative error.

By comparing the two thermal conductivity calculation methods, extremum method and fitting method, it was proposed that the

extremum method will be the first choice so long as the sampling rate was high enough.

This paper deals with three gravity satellites, namely CHAMP, GRACE and GOCE. Satellite gravity data are widely used in such fields as the recovery of the earth's gravity field, the land water storage, the study of the geoid change, the elastic thickness, the crustal thickness, the gravity variance before and after earthquake and the crustal movement. Lots of successful and valuable research results were obtained. It is considered that the satellite gravity survey technology is by for superior to traditional gravity survey and will surely have larger application space.

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.

1995 was the last year of China's Eighth Five-Year Plan.Over the past five years,oil and gas geophysical work has developed steadily;techniques such as three-dimensional seism,reservoir description and transverse prediction geophysics have made considerable progress;three-dimensional seismic pre-stack depth offset processing has begun its application;more importance has been attached to direct oil and gas goophysical prospecting technology; some problems such as nonlinear inversion,viscosity and elasticity,double phase and anisotropic media have become focuses of the research.Geophysical work on solid resources has not yet got itself out of the depression;nevertheless,the related techniques remain in progress Our own sofware and hardware system attached to transient electromagnetic method has been basically formed, and gratifying achievements have been acquired in the aspects of distributive type multichannel synchronous electromagnetic system and processing- interpretation working station of integrated electrical method.The increasing market demands for engineering and environmental geophysics have promoted the development of shallow geophysical technique,which,however,still needs the guidance and support from systematic key research projects.

In the light of the pulse width of the radar wave, this paper deals with the difference and the relationship between the vertical resolution and the transverse resolution of the ground-penetrating radar, indicates the influence of the noise upon the resolution and, with practical examples, points out that the digital handling of the signal can greatly improve the resolution of the radar.

Studying the occurrence of natural gas hydrates (NGHs) is of profound significance for NGH exploration. The evaluation of the NGH saturation mainly relies on the Archie equation using the electrical parameters of rocks. The key to accurately calculating the NGH saturation is to select corresponding values of rock electrical parameters for different geological environments, especially the porosity index (m) and the saturation index (n). However, it is still a challenge to select the optimal m and n values for NGH evaluation in resistivity logging. To ascertain the relevant resistivity regularity of NGHs and the determination method of rock electrical parameter values in the Archie equation, this study systematically reviewed relevant references and summarized the resistivity influencing factors of NGHs. Moreover, this study analyzed the influencing factors for the accurate evaluation of the NGH saturation based on the Archie equation. Accordingly, this study generalized the resistivity characteristics of NGH-bearing sediments and proposed the application research direction of the Archie equation.

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.

The spectra of high-order pseudo-random electromagnetic signals encompass all the frequencies required for exploration engineering, it has the characteristics of enhancing work efficiency and strong anti-interference capability, and has been applied in electromagnetic exploration in urban environments. This study extracted effective information from high-order pseudo-random signals in the electromagnetic survey conducted in areas with strong powerline interference within the special exploration area of the Phase I engineering of the Jinan Urban Rail Transit Line 8. To efficiently extract high-quality effective information, an envelope assessment algorithm was combined with high-order pseudo-random signals. Specifically, the actual signal interference was accurately estimated by analyzing the spectral envelope values. This allows for screening received signals, thus further mitigating the impacts of powerline interference and its harmonics. As a result, more effective frequency and geoelectric information were obtained, providing abundant effective electromagnetic data for subsequent inversion and interpretation. The novel method serves as a technique for effective information extraction for future electromagnetic sounding in a complex urban environment.

This study conducted the inversion of the organic matter content in the soil of the black soil area in Sunwu County, Heilongjiang Province using the Sentinel-2A multispectral remote sensing images and the surveyed soil data. After preprocessing the images, the characteristic bands were selected through correlation analysis and using the random forest (RF) method. Subsequently, a multispectral inversion model for the organic matter content of the soil was built using the partial least square method and the BP neural network, and the inversion of the organic matter content of the soil in the Hongqi Forest Farm was conducted. According to the obtained results, the bands selected based on the reciprocal of the logarithm of the first-order differential of reflectance through the correlation analysis and the combined bands selected using the RF method can effectively improve the inversion precision of the organic matter content in the soil, and the RF-BP neural network model for the combined bands yielded the optimal inversion performance (R²=0.7245 and RMSE=1.3127%). The results of this study will provide technical support and reference for the dynamic monitoring of the organic matter content in soils.

The Salt Lake geothermal field in Yuncheng City, Shanxi Province, China lies beneath a densely populated urban area, posing significant challenges to further geothermal exploration and extraction. Based on the distribution of geothermal gradients in the geothermal field, which are higher in the southwest and lower in the northeast, a NE-trending microtremor survey profile was arranged in the southern part of Yuncheng City, aimed at investigating the deep geothermal reservoir structure and NW-trending structures in the geothermal field. The 2D velocity structure profile reveals a pronounced low-velocity anomaly in the eastern part, which is supposed to be induced by the fault fracture zone formed by multiple NW-striking tensional faults. Spatially, this concealed fault zone roughly corresponds to the low-geothermal gradient anomaly in the northeastern Salt Lake geothermal field, suggesting that this fault fracture zone might facilitate the rapid infiltration of cold surface water, thereby lowering the temperature of deep rocks in the northeastern part, leading to the formation of a large-scale low-temperature anomaly zone. Additionally, the faults identified by the microtremor survey can be traceable and confirmed in a controlled source reflection seismic profile in the study area, demonstrating the complementary nature of the two methods. This study further reveals the deep geothermal structures of the Salt Lake geothermal field based on previous efforts. This study provides more valuable bases and guidance for future exploration and resource evaluation of geothermal fields in the region while also demonstrating the effectiveness and superiority of the microtremor survey method in research on urban geothermal resources.

It is more difficult to predict the low porosity and low permeability tight reservoir than to predict the regular reservoir.The authors therefore tentatively applied kernel principal component analysis and support vector machine,called KPCA-SVM model,to solve this problem.Through the polynomial kernel function of the KPCA,the model can obtain the nonlinear feature extraction.Then the Gaussian kernel function in the SVM is chosen to perform optimization again.Finally,reservoir identification is implemented in the SVM.As the model incorporates the advantages of kernel function,principal component analysis and support vector classification,it can better solve the problem of nonlinear small sample,eliminate the noise of the data and reduce the dimension without missing valid information.In addition,it can achieve the prediction function quickly and accurately.The model was employed to predict the reservoir in x856 well block,which belongs to Xu2 member gas reservoir of the Xinchang gas field.The prediction results show the superiority of this model,which can be used as an optional method in tight reservoir prediction.

This paper deals with the standing wave resulting from the interference of the reflection electromagnetic wave when the electromagnetic wave is transmitted and perpendicular to the strata. The conditions of antinode and node formed on the ground are also discussed. According to the equation deduced by the author, the thickness of the strata and the relative sizes of the electromagnetic parameters in the media on the two sides of the bottom interface of the strata can be determined by measuring the frequency of the antinode. It is also pointed out that at least four natural electromagnetic wave sources can be used in geophysical exploration based on the electromagnetic standing wave method.

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

The tin-polymetallic mining area of the Yue'e ore district, XiengKhouang Province, Laos, is located in the west of the XiengKhouang Laos-Changshan Vietnam tectonic magmatic belt. Based on the 1:25 000 valley system soil geochemical survey, combined with an analysis of the characteristics of element variation coefficients and concentration coefficients, the correlation of elements, anomaly verification, and gold and other polymetallic ore prospecting potentials, the authors optimized multiple target and prospects areas. The position of the mineralized body was inferred based on geochemical exploration anomalies in key target areas. Through trench verification and drilling engineering verification, good prospecting results were achieved. The area is considered to have copper, tin, lead, zinc, tungsten. It is shown that this method can quickly delineate the prospecting target area and distant scenic area in the thick coverage area and extensive blank research area of Southeast Asian tropical monsoon climate, and can provide an effective basis for the next exploration work.

This paper has summed up the development and new application of ground-searching radar in recent years. Based on detailed analysis of the principle and system structure of ground-searching radar, the authors put forward the train of thought for improving system structure of ground-searching radar and, aimed at solving the great noise existing in ground-searching radar work and the inadaptability in transplantation of seismic data-processing technique, raise a new scheme for underground interface high-resolution imaging of ground-searching radar.

The telecontrol electrode array is a new type of electrode array for power supply and observations that utilizes the carrier waves of the power-supply and measurement wires used in conventional electrical prospecting to transmit signals. By remotely controlling a series of coded electrode switches between various wires and their connections, this array allows for orderly power supply and measurements. This array enables flexible spacings between electrodes and the gradual expansion of the distances between power supply electrodes via remote control, thus achieving a gradient-based sounding array. The borrowing-line remote controller can be used combined with single-channel, multi-channel, and high-density resistivity instruments, and the combined arrays can perform 2D/3D electrical prospecting more effectively. Followed by the brief introduction of the principle of the borrowed-line telecontrol electrode array, this study discusses the applications and examples of this array and several combined arrays in the resistivity method and induced polarization (IP).

This paper makes a generalized description of the scientific and technical advances in magnetic prospecting in China, which include such aspects as gro und magnetic survey, acromagnetic survey, marine magnetic survey, magnetism of rocks, paleomagnetism, absolute measurement of geomagnetic field. data pro cessing and interpretation of magnetic anomalies, and development tendency of this field.

Based on lithologic logging interpretation, the authors identified typical fracture sections according to their logging response calibrated by core data integrating drilling mud leakage, drilling break and production data. Then the typical logging response of fracture section was employed as training samples for Artificial Neural Network Pattern Recognition (NNPR). All the 76 wells in the Qijia buried hill were processed by applying the ability of NNPR including paralleling process, distribution information storage, powerful self-study and automatic weight value adjustment. Finally, a new fracture prediction method integrating core, conventional logging, test and production data was formulated, which has been proved to be effective by drilling.

With the geochemical multidimensional anomaly system, the development and application of geochemical anomaly structure's 3D visualization have been carried out. Geochemical anomaly structure applied to the deep ore body prediction collects samples from drill core to get geochemical 3D data. So researchers urgently want to explain and map them. The geochemical anomaly structure system has been developed on the platform of MapGIS K9 using 3D visualization and 3D geological model technology. It has not only realized the integrating of data models on the ground and underground but also the integrating of solid models and attribute models. Analyzing geochemical anomaly structures and exploring ore models could be done in this system. The thought and technology for 3D anomaly structure and its application in the Matou mining area of Anhui Province have been elaborated in this paper.

According to the data characteristics of mineral resources exploration, this paper has studied the volume rendering algorithm model and the spatial interpolation method suitable for 3D visualization of geological information. Based on IDL platform, the authors developed the software for 3D visualization,which can display rapidly and exactly the lithological and physical properties of the geological body. In addition, the checking of the 3D visualization techniques was completed based on the borehole data of a metallic deposit in Inner Mongolia, and the effects prove to be satisfactory.

Airborne gravimetry uses aircraft as a carrier to collect data of gravity field. Due to the influence of air flow, flight state and body vibration, the original data of airborne gravity measurement contain a large amount of noise, and the SNR is as high as the grade of several thousand to ten thousand. This becomes a technical problem for the development of airborne gravity measurement system to obtain the weak gravity signal from the original measurement data. In this paper, the general Kalman filter formula with certain control was adjusted for adaptability based on airborne gravity measurement system, the mathematical model of the airborne gravity anomaly was established, and the Kalman filter state equation was proposed for measuring principle of the system. Finally, the authors solved the problem of gravity signal and differential GNSS signals matching and airborne gravity of weak signal extraction. After the test of airborne gravity measurement data, the proposed airborne gravity data solution method can be used to solve airborne gravity anomalies with high accuracy, and the result is better than the FIR low-pass filter (currently used in engineering) solution results, which promotes the development of airborne gravity weak signal extraction technology.

Unfavorable geobodies such as Karsts, weak soil, and water-rich areas are extensively distributed in China. Under heavy rainfall, they are prone to geologic hazards like collapse. A severe geological collapse occurred in Xiacun Town, Yushui District, Xinyu City, near the Shanghai-Kunming high-speed railway. The space around the collapsed foundation pit was limited, with many interference sources like underground pipelines. With early signals subjected to the mutual inductance effects of receiver and transmitter coils, the conventional transient electromagnetic method exhibited low detection accuracy and anti-interference ability, encountering significant shallow blind zones. To locate unfavorable geobodies in the study area and provide suggestions for the prevention and control of geologic hazards, this study innovatively applied the opposing-coils transient electromagnetic method (OCTEM), supplemented by borehole-based verification. The results show that: (1) The OCTEM exhibited high accuracy, as demonstrated by the high consistency between the geophysical exploration results and the drilling results of the study area; (2) The low-resistivity zone spread across the study area, and the low-resistivity anomalies revealed by geophysical exploration were caused by groundwater according to borehole-based verification; (3) The strata from top to bottom were composed of soft plastic silty clay, hard plastic silty clay, soft plastic silty clay, and moderately weathered limestones; (4) The subsurface micro-confined water in the collapse area surged upward, gradually eroding the soft plastic silty clay layer around the area. The static water level in the collapsed foundation pit manifested an elevation of 55.60 m, located approximately 1.4 m below the surface; (5) A groundwater channel existed under the collapse area, with soil caves formed in the limestone layer under the prolonged erosion effect of water flow; (6) Long-term groundwater extraction may expand the underground seepage zone; (7) The administrative department in charge must promptly contain groundwater in the collapse area to prevent it from further eroding the surrounding unconsolidated soil layer.

This paper deals in detail with the basic principles and interpretation techniques forthe detection of underground line pipes with the direct detection mothod.It advances a new vectorintersection drawing method for determining positions and depths of line Pipes and givingconfidence of the detection results.Results with high. confidence can ho provided in situ.Description is also made con-cerning the instrument and equipment for line pipe detection and their application of effects.

Non-destructive testing of the internal structural characteristics of ancient buildings is the key to preserving cultural relics.To determine the structures and internal defects of the ancient Great Wall in Linhai City,this study performed non-destructive testing of the wall structures in different orientations using a ground-penetrating radar (GPR) combining 100 MHz and 270 MHz antennas.The testing results show significant structural stratification in the ancient Great Wall.The GPR signal-reflected images reveal clear internal wall defects like pores,cracks,voids,and other hidden dangers.This study demonstrates the reliability of the GPR in detecting structures and defects of ancient walls,there by providing technical support for the structural protection of the ancient Great Wall.

According to the physical character difference between the exploration object geological body (silver polymetal-bearing structural alteration zone and granite porphyry mass) and the wall rock, the authors employed such integrated geophysical exploration methods as high-precision magnetic survey, IP intermediate gradient and IP sounding to prospecting for concealed silver polymetallic deposits in the shallow cover area of eastern Xiaoshan. High-precision magnetic survey was used to divide favorable prospecting targets, IP intermediate gradient method was utilized to delineate favorable ore-forming sectors of mineralization and alteration, and IP sounding was used to optimize drill hole layout. In this way, the ore-intersecting rate was increased, and important breakthrough was made in ore prospecting.

The eastern Kunlun metallogenic belt, as a significant metal metallogenic belt in China, hosts extensive orogenic gold deposits and large-scale Kunlunhe, Gouli, and Wulonggou gold concentration areas. The Dachaigou gold deposit is a large-scale gold deposit newly discovered in the Wulonggou gold field in recent years. Despite its high metallogenic potential, the western extension of its ore belt has not been defined. Hence, this study conducted induced polarization (IP) sounding and wide-field electromagnetic sounding in the deposit. The results show that the known ore belt is situated in the regional gravity anomaly gradient zone, the transition zone of positive and negative weak magnetic anomalies, the edge of IP anomalies, or the electrical gradient zone. The development zone of the regional tectonic belt resides in the large-scale IP anomaly section. The regional tectonic belt is characterized by a wide range of low-resistivity anomaly zones. The IV and III alteration zones of the known ore belt are located in the opening position of the low-resistivity anomaly zone and the shallow electrical anomaly gradient zone, respectively. Based on the above understanding and the electromagnetic anomaly change patterns of several parallel profiles in the western extension segment, it was inferred that the regional ore-controlling structure extends steadily in the W-NWW direction, forming a favorable prospecting space in the western extension segment of the deposit. The results of deep geophysical exploration in the Dachaigou deposit indicate that geophysical methods manifest significant advantages in deep geological prospecting research, providing successful experience for deep prospecting in the eastern Kunlun gold deposit area.

The method of structural superimposed halo to find blind ore is a new method to find blind ore, which is based on the study of the theory of primary halo to find blind ore-the axial zoning of primary halo, and puts forward two new theories of ‘primary superimposed halo theory’ and ‘structural superimposed halo theory’. The accuracy of blind ore prediction by superimposed halo of structure is determined by the correctness of prediction marks and indexes. Based on the summary of seven common signs of structural superimposed halos in the prediction of deep blind ore deposits in more than 100 hydrothermal deposits, four important quantitative qualitative prediction signs are upgraded to quantitative prediction indicators. The structural superimposed halo prediction signs and indicators of 17 different combinations of accurate prediction of blind ore and discrimination of ore body denudation degree in the deep and periphery of the mining area are described in detail, and a practical ideal model of structural superimposed halo for predicting blind ore and discriminating ore body denudation degree is established. The common prediction signs and indicators of the model have important guiding significance for the prediction of deep blind ore in typical hydrothermal deposits, and have achieved remarkable prospecting results in more than 100 mine applications.

Based on the analysis of selenium content in soil and agricultural products in the study area, the authors studied the distribution characteristics and influencing factors of total selenium, and analyzed the characteristics of selenium content in agricultural products. The results show that the selenium contents were controlled by the geological background. It was much higher in the Third and Fourth members of Jurassic Nanyuan formation than in other geological background regions.In addition, the contents of selenium in soil under different soil types showed a great difference, and the land use types also has a certain impact on it. The correlation analysis indicates that the selenium content in soil has a significant correlation with pH, organic matter and metal oxides such as TFe₂O₃, indicating that the physicochemical properties of soil play important roles in the geochemical behaviors of selenium. The significant correlation between the selenium content and heavy metals indicates that there is a certain assorted relation between selenium and heavy metals in primary sulfide mineral.

This paper briefly reviews the history and the overall work deployment of the U.S. National Uranium Resource Evaluation (NURE) program, with emphasis placed on the key techniques of airborne exploration. The airborne exploration included airborne gamma-ray spectrometry (AGRS) and aeromagnetic survey, which collected radiometric and magnetic data over the conterminous United States and Alaska. The airborne program systematically covered each 1° by 2° national topographic map series (NTMS) quadrangles, which were used to locate potential radioactive mineral deposits. The program played an important role in uranium resource and environmental radiation level evaluation, which has far-reaching definition and meaning. The experience and practices of the program should be used for reference. According to the current status of China's survey, top-level design for AGRS should be strengthened. This paper also proposes a national program of AGRS surveys for achieving coverage of terrestrial radioactivity and building a measurement and monitoring system with Chinese characteristics.

The time-lapse resistivity method can be applied to engineering and environmental problems such as monitor groundwater contaminant transport, measure slope stability. In this paper, the normalized data inversion result of the time-lapse resistivity method was used to identify the subsurface structure of small resistivity changes. First, the data ratio normalization was adopted in which the initial data serve as the background data to normalize the data at other times. Next, the separate nonlinear conjugate gradients (NLCG) inversion result of initial data, time-lapse data and normalized time-lapse data were implemented. The same inverted parameters and homogenous half space model that was taken as the reference model were applied in all synthetic data examples. The inversion results show that the normalized data inversion results can effectively distinguish the small changes of resistivity relative to the background, but the conventional resistivity inversion almost cannot recognize it.

Rock physics lies in the study of the physical properties of rocks related to seismic properties, especially the quantitative study of the relationship between elastic properties of rocks and their seismic properties with various fluid distributions. This relationship is important in the prospecting and exploitation of oil and gas, and hence rock physics is highly praised as a tool for"opening the door to quantitative interpretation". This paper has briefly reviewed the development of the rock physics and described the designing objects of the rock physics analysis system (RPAS). By combining core measurements with well logging and seismic information, RPAS provides a convenient tool for theoretical and experimental analysis. The ideas behind the design and implementation of RPAS are given, and the user's needs are analyzed. This paper describes the framework of RPAS and its concrete functions. Developed by object-oriented programming and Qt, RPAS is characterized by friendly graphical interface and flexible interactive manipulations. It is open and easy to transplant.

As a method for effectively reducing the velocity model of the subsurface media,seismic tomography provides a reliable initial velocity model for full waveform inversion.The finite frequency characteristics of seismic wave propagation are realized from primitive ray toe to phase shift travel time tomography and instantaneous travel time tomography.From the acoustic wave equation to the elastic wave equation and from the isotropic medium to the VTI,TTI media,the simulation of the real underground medium is realized.The morbidity of mitigating tomographic inversion has also been a research hotspot.The commonly used methods have regularization,and the sensitive nucleus of Gaussian beam tomography has replaced the traditional ray-sensitive nucleus.Furthermore,in order to avoid the dependence of the accuracy of the imaging results on the true depth of the reflection bits on the common imaging gather,the angular domain double differential reflection tomography can converge stably and efficiently to the accurate migration velocity model.At present,tomography is gradually transitional to anisotropic media,data used are transitional from VSP to WVSP,and a single waveform is developed into multiple waveforms combined inversion.However,problems related to resolution and computational efficiency still require attention.

The zero-offset (z₀) section is an important achievement in seismic reflection imaging. The differences between the common midpoint (CMP) and the common reflection point (CRP) are discussed on the basis of the dome-like reflector model. In usual seismic data processing, we cannot get the correct z₀ sections if oblique layers are imaged. However, the prestack time migration technique using CRP stacking can help us to obtain the correct z₀ sections. This paper discusses the key steps in the application of such prestack time migration techniques as seismic data preprocessing, construction of migration-velocity field and CRP gather processing after migration. The processing effects are demonstrated with real data.

Survey grid layout is a preliminary task of geophysical and geochemical exploration. The widespread use of handheld GPS has greatly facilitated navigation and positioning in small-to medium-scale geophysical and geochemical field surveys. This study, based on coordinate transformation theory, presented a method for generating large numbers of GPS waypoints for both regular and irregular survey grids for geophysical and geochemical exploration. Furthermore, an associated software program was developed. The software enjoys simple interfaces and convenient operations, enabling the quick generation of survey grids suitable for applications such as gravity, magnetic, and resistivity surveys, soil surveys, and stream sediment surveys. Therefore, this software can be used for field navigation.

Based on studying the distribution of trace elements in the dioritic weathered crust of Zigui area, the authors have divided the trace elements into three types. The first type consists of inactive elements which include Sc, V, Cr, Co, Ni, Cu, Zn, Zr, Hf, Nb and Ta, U, Th, Mo, W. During the weathering process, they can be effectively preserved. Due to the influence of redox condition variation, U, Cr and Cu sometimes show local enrichment, without obvious regularity. The second type is composed of active elements such as Ca, Rb, Cs, Sr, Ba, Pb, Ga, Gd, and Tl, which are gradually leached from profiles along with the weathering. The third type is represented by REE, which are leached from the upper section downward, and enrichment is observed in the mid-lower section, with the leaching degree of HREE higher than that of LREE. Eu gradually changes from positive anomalies in parent rocks into negative anomalies on the surface due to the weathering leaching of plagioclase in parent rocks under the oxidation environment. Under the surface oxidation condition, Ce easily produces tetravalence oxides (cerianite) and shows obvious surface enrichment, and the variation of the redox conditions leads to the undulate variation of Ce.

This study aims to ascertain the heavy metal pollution of groundwater in a typical chemical industry park in northwestern Shandong. According to the investigation and evaluation requirements for groundwater environments in chemical industry parks, this study collected 10 groundwater samples to analyze the concentrations and spatial distributions of eight heavy metals, namely Fe, Cu, Zn, Al, Cd and Pb. Furthermore, it conducted the health risk assessment of groundwater for different populations. The results indicate that: (1) except Mn and Al, all heavy metals in the groundwater of the chemical industry park showed concentrations lower than the class III water quality standard stated in the Standard for Groundwater Quality (GB/T 14848—2017), with a comprehensive pollution index ranging from 0.37 to 0.78. The monitoring points for heavy metal elements are all pollution-free; (2) the overall spatial distributions of heavy metals are roughly consistent with the distribution areas of key enterprises in the chemical industry park. This consistency indicates that external factors such as the production activities of enterprises affect the spatial distributions of heavy metals in groundwater; (3) the health risks are lower for children than for adults and lower via skin contact than via drinking. The non-carcinogenic risks under different exposure routes are acceptable for different populations. Carcinogens As and Cd have slight carcinogenic risks for adults. Local authorities should strengthen the supervision of the production activities of enterprises and thoroughly inspect enterprises with suspected pollution. Only in this way can we effectively control and then gradually reduce the risks to human health caused by groundwater pollution.