After analyzing the power supply system design of airborne gravity measurement, aiming at the instability of full load power on or repeated start, a new circuit connection mode based on VICOR power module is proposed to solve the above problems. In the design of aviation gravity power supply, the general circuit structure design and parameter selection refer to the technical manual of the power chip module manufacturer, and the EN port of the rectifier filter module is selected to drive the DC-DC module. However, similar faults such as full load power on difficulty or repeated startup are often encountered, which affect the stable operation of the power supply. In this paper, the BOK output of VICOR module combined with triode is used to control the PC enable port of DC-DC power supply module, which does not affect the power on of front-end rectifier filter circuit. The circuit analysis results show that compared with the EN port drive enable, when using the BOK drive, the threshold voltage lower than 2.3 V can be guaranteed at the output low level, the PC enable port can be fully blocked, and there will be no phenomena such as full load power on difficulty or repeated startup, so that the aviation gravity power supply system can work more safely and stably.

Soil geochemical background investigation was carried out in the scallion growing area and planned scallion area of Zhangqiu. It is found that the surface soil of these areas has high level of Se, B, P, N, S and low level of F, Mo, CaO. The richness of the beneficial elements, especially Se, constitutes the favorable prerequisite for the development of a Se-rich agricultural base area. Soil fertility status and environmental quality in the region are both good, Se and heavy metal elements values in scallion have a close relationship with their values in soil. A comparison with the green and pollution-free food producing soil standards shows that the survey area land has a high degree of security, which makes the area very suitable for the scallion cultivation. On such a basis, the authors put forward the Se-rich scallion planting plan for Zhangqiu, and the whole work region can be divided into four planning areas: the most suitable area, the comparatively suitable area, the somewhat suitable area and the unsuitable area. The feasibility of developing Zhangqiu Se-rich scallion is discussed in this paper, which may be used as a reference for optimizing the cultivation of Zhangqiu Se-rich scallion and making the plan for further development.

The Stratagem ^TMEH-4 electrical conductivity image-forming system is a magnetotelluric sounding system which combines partly controllable source and natural field source and consists of receiving device and emitter. Based on the exploration object, one can use high-frequency allocation (10 Hz～100 kHz) or low frequency allocation (0.1 Hz～1000 Hz). By collecting two sets of electromagnetic signals (E_x, H_y, E_y, H_x) in time domain which are perpendicular to each other and through spectral analysis and calculation, the variation curves of different frequencies, resistivities, phases and correlation degrees can be drawn. By analysing and comparing these curves, the on-the-spot judgement of data quality can be carried out, the EMAP two-dimensional continuous profiling inversion can be conducted for continuous inversion result of one-dimensional apparent resistivity of measuring points along the profile, and the gray level diagram of the resistivity section can be illustrated. As a result, preliminary interpretation of the exploration result may be made immediately.Three fields work examples are given in this paper.

 In extracting average velocity fields, the choice of different datum planes can lead to different timetodepth conversion results. In the twostep static correction used at present, there are two datum planes to construct the average velocity field and perform the timetodepth conversion: one is the velocity spectrum analyzing datum plane, i.e., the CMP datum plane, and the other is the final seismic datum plane, i.e., the common datum plane. The velocity field and timetodepth conversion were studied on these two different datum planes, and a method was put forward for deriving a smoothed nearsurface plane for timetodepth conversion by averaging all elevations of each receiver and each shot point within the scope of a CMP gathered. A case study shows that this method can provide higher precision velocity field and structure map without using any borehole data than the routine velocity field study method on common datum plane.

Based on the data of soil element content obtained from agricultural geological survey in Wuping County, Fujian Province, the authors studied the distribution characteristics of soil selenium content and its controlling factors. According to the result obtained, the average value of selenium content in the study area is 0.25×10^-6, the high value area of soil selenium is mainly distributed in the south and east of the investigation area, and the average value of selenium content is 0.42×10^-6, reaching the standard of selenium enrichment; the selenium content of the soil in the study area is mainly controlled by the geological background, and the content of selenium in the Carboniferous and Permiancarbonate strata and coal-bearing strata is relatively high The average selenium content of marine sedimentary rock area is the highest, reaching 0.34×10^-6. The average values of selenium content in pyroclastic rock, granite area and metamorphic rock area are similar, being 0.25×10^-6 and 0.24×10^-6, respectively. Soil selenium content in tea garden (0.57×10^-6) and orchard (0.40×10^-6) is higher than that in paddy field (0.25×10^-6). Soil physical and chemical properties have an important impact on selenium content, which shows that soil selenium content has significant correlation with soil pH, organic matter and iron oxide.

Based on the method for evaluating oil and gas geochemical anomaly and the principle for formulating its parameters,this paper points out that the formulated parameters should not only have definite geological and geochemical implications but also accord with a certain mathematical principle as well as the optimization criterion.On such a basis, the paper deals with the attributes of anomaly and background as well as methods for their determination,describes roughly the criteria for judging oil and gas anomalies,emphasizes the importance of the correlation between composite anomalies and variables as well as the extraction of associated information.

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 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.

Over the past nearly 30 years,geophysical technical standards for geological surveys have successively experienced zero standards,sparse standards,and standard series.As a result,a series of standard systems of gravity,magnetic,electrical,seismic,and radioactive prospecting have been gradually established,which play an important role in establishing standardized work procedures and promoting new methods and techniques in the field of geophysical techniques for geological surveys in China.However,with the transformation and development of geological surveys in China,the current standard systems of geophysical prospecting are yet to meet the requirements of geological surveys at present.The paper summarizes the development status of geophysical standards for geological surveys in China and explores the research direction and development trend of the standardization of geophysical techniques according to the need for geophysical methods and technologies in the transformation and development of geological surveys in China.

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

China's complicated geological background and metallogenic environment have decided that the regional geochemical exploration can play an important role in the field of China's mineral resources prospecting. This is the strategic selection under special metallogenic conditions. The first round of regional geochemical exploration of China was carried out during mid-1950s. Since then, we carried out the second and third round of regional geochemical exploration. Until now, China's regional geochemical exploration has gone through a history of 70 years, and showed unique functions in fields of the exploration and development of nonferrous metals, precious metals as well as the rare minerals, rare earth and scattered minerals. According to incomplete statistics, during 36 years (1979~2015) of the second and third round of regional geochemical exploration, totally 182 different kinds of large to super-large scale deposits were discovered in China mainly by means of regional geochemical exploration. Of which, 61 deposits have nonferrous metals, 93 deposits have precious metals, 24 deposits have critical and scarce minerals, and 4 deposits have other kinds of minerals. On average, 5.06 large to super-large deposits were discovered each year, and one large to super-large deposit was discovered within every 37,000 square kilometers-Calculated on the basis that the second and third round of regional geochemical exploration covered 6.68 million square kilometers' area of China. Regional geochemical exploration has achieved outstanding results in the field of mineral prospecting, and made great contributions in terms of ensuring and promoting China's economic development. As our country's basic, public good and strategic geological work, regional geochemical exploration comes into the 21^st century marked by big data and earth system science. Based on high precision and good quality big data, guided by metallogenic geochemical theories, and supported by modern science and technology, the regional geochemical exploration will start a new period of development. In the future, we'll continue to carry out the high technical standard and high quality regional geochemical exploration, achieve our goal of complete covering the whole area of mainland China with regional geochemical exploration, and provide more strategic prospective areas for our country's mineral resources exploration. On the basis of high-precision big data, metallogenic theories and modern science and technology, we'll establish AI and IT application system, so as to push forward the exploration and utilization of deep minerals, buried deposits as well as the critical and scarce minerals which are difficult to identify, and achieve greater breakthroughs in the geological exploration of mineral resources. By using big data technics, China's regional geochemical exploration team will continuously solve the mineral resources exploration and evaluation problems, and in this process, our geochemical exploration system will be gradually integrated into our country's science and technology advancement.

The one-dimensional inversion of induced polarization (IP) sounding data involves multi-parameter nonlinear optimization. This study achieved the one-dimensional (1D) inversion of IP sounding data based on the improved global optimization algorithm of differential evolution (DE) with two-step mutation. The conventional DE algorithm includes mutation (single-step), crossover, and selection operations. The two-step mutation method proposed in this study can produce new individuals through the mutation of the optimal individual and two randomly selected individuals in steps, thus enhancing the influence of the optimal individual and the global optimization ability. The model test results show that the two-step mutation method has a higher optimization ability than the conventional method. Specifically, the polarizability parameters were loaded using the equivalent resistivity method, and the surface IP sounding resistivity curves of a layered model can be quickly calculated through forward modeling using the digital filtering algorithm. Based on this, the DE algorithm with two-step mutation was employed to produce new individuals through continuous mutation. Then, the resistivity obtained through forward modeling was fitted with the observed values, and the individuals whose fitness approached the maximum fitness were selected as the inversion results. The inversion method proposed in this study features simple operations and fast calculations. As verified through the calculations of H- and KH-type geoelectric models, the inversion method enjoys high fitting accuracy.

Accurately and quickly determining the geological properties related to magnetic anomaly sources is a key technical challenge in magnetic prospecting, directly influencing the accuracy of geological interpretation using magnetic survey data. The induced magnetization varies with time, whereas the remanent magnetization typically remains constant over time. Therefore, there exists a theoretical basis for investigating the properties of magnetic anomaly source bodies by detecting the time variations of magnetic anomaly intensity. Despite geophysicists' relevant research in this field, practical technical methods have not been established. Hence, this study proposed a novel method for determining magnetite ore-induced magnetic anomalies. Based on the observational data of geomagnetic diurnal variations, the proposed method constructed parameters, including the variations (A), variation rate (η), and normalized variations (F) of magnetic anomaly intensity, to evaluate the properties of strong magnetic anomaly source bodies. Accordingly, the proposed method determined the possibility of magnetite ore-induced magnetic anomalies, showing critical significance for magnetite exploration.

A soil gas radon survey was performed on a large scale to determine the distribution of radon in soil of Zhuhai City in Guangdong Province by means of a portable radon monitor of a semiconductor alpha spectroscopy. The survey sampled 469 sites covering an area of more than 100 km². The average of soil radon concentration in the soil depth of 0.6 m is 55.94 ± 58.54 kBq/m³ in Zhuhai urban area, whereas the concentration is 7.14±8.75, 37.64±25.92, and 151.25±196.23 kBq/m³ in the Quaternary sediments, the mixtures of sediments and weathered grain of granite, and the weathered granite in Doumen District, respectively. The high radon potential areas are located within biotitic granites and new industrial districts, as indicated by the strong correlation between the radioactivity level and geological lithology. The mean value of soil gas radon concentration in Zhuhai urban area (ZUA) is about ten times as high as that in Guangzhou, Quanzhou and Jinjing City. The results show that Zhuhai area has higher radon potential, and hence protective measures against radon should be taken into account.

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.

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.

To improve the detection level of municipal roads for rapid and effective municipal road collapse warning and rapid search for municipal pipe network distribution, the 22^nd Research Institute of China Electronics Technology Group Corporation designed and developed real-time three-dimensional ground-penetrating radar (3D GPR). With the real-time 3D GPR, which is based on the architecture of field programmable gate array and digital signal processor (FPGA&DSP), the institute achieved the design and implementation of several key technologies for the multi-channel high-speed acquisition system, enriching the road detection techniques and methods. The real-time 3D GPR enables high-speed acquisition of ten-channel radar data using the horizontally polarized antennae equipped with five transmitters and six receivers. The channels can be switched using high-speed switches, which operate in an interactive interpolation manner. The 3D GPR allows for up to 32 channels and detection speeds of above 60 km/h (channel interval: 2 cm). This is attributed to the switching of the antenna array using switches. The optimum antenna polarization design was verified by the comparison of experimental data from cavity- and metal-plate-based experimental sites. As a result, the optimal antenna scheme was determined. The measured results show that, compared to general LTD-2600 radar, the real-time 3D GPR boasts a higher acquisition speed and higher performance in terms of amplitude and phase, conducive to the improvement of road disaster detection technologies. Therefore, there is high market demand for the real-time 3D GPR.

Due to historical reasons, the present coordinate systems of the geological, geophysical and geochemical exploration results are basically WGS84, BJ54 or XA80 systems; nevertheless, according to the NASG requirements on the overall use of CGCS2000 coordinates, in the future the coordinates for all kinds of results should be CGCS2000 coordinates, which causes inconvenient situation in using the results and in comprehensive research work. As a professional geographic information system software, ArcGIS has a wide range of applications in various walks. In this paper, the authors briefly introduced the ArcGIS built-in coordinate system, studied and deduced the calculation formula of the MOLODENSKY coordinate conversion method in ArcGIS, put forward the method to get the conversion and precision evaluation of transformation parameters between different ellipsoids, and cited practical examples for verification. On such a basis, the specific ideas and points for attention were analyzed for each coordinate system in the conversion of ArcGIS software to CGCS2000.

Four basic problems in the application of Ground penetrtion-radar are discussed in this paper:(1) the wave-impedance of electromagnetic wave transmission in strata; (2) the reflectivity and transmissivity of electromagnetic field at the subsurface of strata; (3) reflective phase and propagating velocity of electromagnetic wave in strta; (4) detection depth of the Ground-penetration radar.

Influenced by normal fault F2 of right abutment,karst is extensively developed in a reservoir and, as a result, there exists the leakage problem. Although several anti-seepage treatments have been conducted,leakage problem still exists in the near-dam reservoir area,and the situation has been getting worse and worse. In this study. the seepage of the reservoir was detected by flow field method,natural electric field method and high density resistance method. According to the results obtained, comprehensive geophysical prospecting method can accurately obtain the location information of seepage source and seepage channel of the reservoir; the sealing quality of old tunnels is poor and there are leakage problems, which also leads to concentrated seepage and large-scale scattered immersion of the downstream side dam body; the low mountain body on the right bank of the dam has seepage entrance and may be connected with the spring water point at the foot of the downstream mountain; the F2 fault zone on the right abutment of the dam has poor imperviousness,and there exists a leakage passage connected with the concentrated seepage points at the outcrop of downstream faults.

The artificial source electromagnetic method is an important technique for deep resource exploration. The key challenge is to improve the depth and precision of detection through innovative technology. The detection mode of electromagnetic methods is evolving from far-field to near-field, and the study of near-source electromagnetic methods has become an international research frontier in recent years. Building on the recent advancements in wide-field electromagnetic methods and multi-channel transient electromagnetic methods, the short-offset transient electromagnetic method (SOTEM) has been further developed and proposed. The distinguishing features of SOTEM are its stronger signals and wider bandwidth, which are advantageous for achieving the detection requirements of greater depth and higher precision. This special issue presents eight articles covering the methods, techniques, software, and applications of SOTEM, providing strong support for the growing need for high-resolution subsurface detection.

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.

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.

The concept of deep penetration exploration geochemistry is proposed by the author based on the latest advances of geochemical methods for deeply concealed deposits. Deep penetration exploration geochemistry, a new branch of exploration geochemistry, involves the measurement of any direct geochemical information emanating from the deeply concealed deposits. Its purpose is to find deeply concealed deposits by employing newly recognized geochemical methods which can penetrate thick overburden. Abrief description of its research scope and necessity is given in this paper.

The Galinge iron deposit in Qinghai is overlain by deposits measuring greater than 150 m in thickness. The great burial depths of ore bodies lead to gentle magnetic anomaly morphology, making it difficult to characterize the spatial distribution of ore bodies. Therefore, this study employed three-dimensional magnetic anomaly inversion to determine the three-dimensional distribution characteristics of subsurface magnetic intensity in the study area. Given the prior information of non-magnetic surrounding rocks, the three-dimensional magnetic intensity model clearly presented the spatial distribution of the ore bodies and reflected the presence of intense magnetic bodies at depths of less than 500 m in existing boreholes. Accordingly, it can be inferred that there exist concealed ore bodies at depths exceeding 500 m in the study area. The results of this study suggest that three-dimensional magnetic anomaly inversion can effectively improve target identification, providing clear information on the horizontal positions, depths, and scales of magnetic ore bodies. The proposed inversion method can offer strong support for drilling design and reserve estimation, warranting promotion in detailed exploration of solid minerals.

To reduce the economic losses caused by pipeline leakage, this paper applies a comprehensive geophysical exploration technology integrating ground-penetrating radar, multi-channel transient surface waves, and resistivity imaging to detect pipeline leakage at a power plant in Huainan, Anhui Province. The results show that the ground-penetrating radar oscillatory signals can reveal the leakage zone, the multi-channel transient surface wave can reflect the leakage severity within the detected area, and the electrical resistivity tomography can present the low-resistance morphology of the leakage zone. Demonstrated by the satisfactory outcomes, this integrated geophysical prospecting method proves to be an effective means to accurately locate the leakage positions for similar pipelines.

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.

Some new advances in detecting geological formations by acoustic signal are described in this paper. The basic principle and characteristics of non-linear (parametric) sonar system are elaborated. Lots of case studies have been made for the efficiency evaluation of the SES-96 system.

The calculation of the lower limit of the geochemical anomaly and the map compilation are of key and basic importance in the interpretation and appraisal of geochemical anomaly.This paper deals with the determination of the threshold of the geochemical anomaly with VBA programming based on average value and two times of standard deviation,and the method for direct compilation of the discrete point position map with MapGIS.The VBA and MapGIS were combined with each other and applied on the basis of the authors' experience, with satisfactory result obtained. It is pointed out that VBA and MapGIS have wide application prospects in geology and mining industry.

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.

As resource exploration deepens and becomes increasingly difficult,improving the imaging precision and the reservoir prediction accuracy under a complex tectonic setting has become a top priority of research.The full waveform inversion (FWI) method developed in recent years can be applied to complex geological structures.This method can reveal structural details in a complex geological setting using the dynamic and kinematic information in the pre-stack seismic wave field.However,this method involves many research elements such as model parameterization,building of inverse error function,data preprocessing,numerical simulation of wavelengths,and wavelet estimation.Thus,its development is bound to be a long-term gradual improvement process.The FWI method has been applied to actual observation data with the development of theory and computer technology.This study introduced the principle and processing flow of the FWI method and summarized its development history and its application status in marine and onshore seismic data,and deep seismic reflection data.Accordingly, this study presented the current application bottlenecks,data processing difficulties, and challenges of deep-crustal inversion imaging for subsequent research and application of the FWI method.

Artificial intelligence algorithms have been developed to automatically identify the spatial structures of formation lithologies from multivariate log data. They represent a promising approach to reducing lithology logging costs and mitigating the subjectivity inherent in lithology identification. Considering the imbalanced distribution of lithology sample data and the spatialtemporal variability in the relationships between log attributes and lithologies, this study constructed a synthetic minority oversampling technique (SMOTE)-long short-term memory (LSTM) hybrid model. The SMOTE algorithm effectively balances the sample distributions of different lithologies, while the LSTM algorithm, using its deep learning architecture, extracts lithological characteristics from the log sequence data. With the borehole log data and lithology records from a sandstone uranium deposit as training data, the SMOTE-LSTM hybrid model achieved a prediction accuracy exceeding 85% in lithology classification. Compared to several other machine learning methods, the SMOTE-LSTM hybrid model demonstrated significantly improved accuracy and reliability in lithology identification.

In the tentative mercurometric survey around the Qin Shi Huang Tomb, a high mercury anomalous area was detected over the tomb. This suggests that there does exist a mercury source at the depth, and that the area of the mercury anomaly might reflect the approximate position of the underground palace. The heat-release mercury study demonstrates that the soil mercury over the Qin Shi Huang Tomb is basically composed of low-temperature mercury, and that soil survey measurement is actually the reflection of low-temperature mercury. The volatile mercury in soil is consistent with the soil mercury; nevertheless, the soil mercury is more stable. Theα-cup radon measurement has yielded preliminary results in the detection of underground mercury source and the locating of subordinate funeral pits.

This study combines the deep learning with the identification of gravity anomaly body. Based on the CNN (convolutional neural network) which has been gaining its use in the past several years in the field of image identification, the contour image of gravity signal is taken as the unidentified image, while the space parameters of the gravity anomaly body will be identified through CNN. In the training phase, a large number of the 3D anomaly bodies are generated with random variation of parameters, then the network is fed with parametric labels and the computed gravity contour images. The testing is performed with generated testing models to estimate the performance of the trained model. The trained CNN accuracy shows excellent accuracy in the identifications. Then the CNN model is tested with measured main gravity anomaly data of Kauring area in West Australia, and the identified parameters of the 3D anomaly body are compared with known results. It is shown that the generalization of CNN can handle identification of the measured gravity data.

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.

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.

Soil carbon pools constitute a crucial part of global terrestrial carbon pools. Hence, investigating soil carbon pools is critical for understanding the global carbon cycle and changes. Based on the soil carbon data obtained from a multi-purpose regional geochemical survey, this study estimated the densities and stocks of organic and inorganic carbon of soil at depths ranging from 0 to 20 cm, 0 to 100 cm, and 0 to 180 cm in oases on the northern margin of the Tarim Basin. Moreover, it delved into the spatial distribution of carbon density. The results of this study are as follows: (1) The compositions of soil carbon pools varied with the soil depth in the study area. At depths ranging from 0 to 20 cm, the organic carbon stocks accounted for 20.66% of the total carbon stocks. With an increase in soil depth, the organic carbon stocks gradually decreased, while the inorganic carbon stocks gradually increased. At depths ranging from 0 to 180 cm, the inorganic carbon stocks represented 85.73% of the total, suggesting that inorganic carbon predominated in the compositions of soil carbon pools; (2) The soil in three depth ranges exhibited organic carbon densities of 1,956.45, 7,913.37, and 119,73.19 t/km², which were all below the national average level, and inorganic carbon densities of 71,722.84, 37,605.54, and 71,914.93 t/km²; (3) The compositions of soil carbon pools varied somewhat across statistical units. In terms of soil types and land use types, the densities of organic and inorganic carbon were higher in fluvo-aquic soil, brown calcic soil, irrigation-silting soil, and solonchak but lower in aeolian sandy soil and irrigated desert soil. Cultivated land exhibited the highest densities of organic and inorganic carbon in the soil, whereas unused and construction land manifested the lowest carbon densities; (4) In terms of topography, undulating mountains manifested the highest soil organic carbon density, whereas alluvial-proluvial plains displayed relatively high inorganic carbon density; (5) The spatial distribution of soil carbon density in the study area was characterized by high organic carbon densities in the Yanqi Basin, medium organic carbon densities in part of Kashgar Delta (western and southern localities and eastern margin), and high inorganic carbon densities in the Aksu area. Overall, under the background of extreme drought, the oases on the northern margin of the Tarim Basin show high potential for inorganic carbon sink, with soil carbon sequestration significantly influenced by soil types, land use types, and geomorphologic landscapes.

Multi-channel gamma-ray spectrometers are necessary for measuring natural and artificial radionuclides. The core of the multi-channel gamma-ray spectrometers is the multi-channel pulse amplitude analysis, which determines the resolution and analysis accuracy of radionuclides. This study introduces the working principle of a multi-channel pulse amplitude analyzer based on linear discharge and describes the methods for analyzing pulse amplitude and obtaining spectrum peaks. Secondly, this study details the design methods of eight important parts of the multi-channel pulse amplitude analyzer, including the design basis, design idea, and feasible schemes. Finally, this study details the logical sequence diagram of the analyzer, laying a foundation for readers to design a multi-channel pulse amplitude analyzer. Using the working principle, design method, and working logic sequence diagram presented in this paper, as well as modern high technology, readers can develop a new type of modern multi-channel pulse analyzer with uniform channel width, excellent differential nonlinearity, and improved resolution of radionuclides, thus better serving the society using gamma-ray spectrum data with higher energy resolution and high measurement accuracy.

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.

With central south Hebei plain as the study area, the authors studied geochemistry of fluorine in detail and explored its controlling factors. The results show that the fluorine content in central south Hebei plain is on the whole high, and the distribution is not uniform, having significant zoning characterized by four high and four low fluorine regions. The distribution of fluorine element in the area is significantly affected by physical geographic factors and artificial factors, with the natural geographic factors play the leading role. In the natural geographical factors, landscape is the main controlling factor, whereas in human factors, fertilizer seems to be the dominant factor.