This paper deals with X-ray fluorescence technique for rapid determination of Si,S,Kand TFe content of iron ore concentrates.The analytical precision and accuracy of this technique are consistent with the chemical analytical error standard and can meet the practical production requirements.

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.

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.

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.

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.

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.

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.

As one of the large tin-polymetallic deposits in the world, the Dachang deposit has complicated metallogenic mechanism and rich hidden mineral resources. In order to detect the distribution and study mineralization mechanism of the concealed deposits around the cage and cover rock in the Dachang ore district, the authors finely processed the audio magnetoelectromagnetic data covering the Dachang ore district, and obtained a two-dimensional electrical structure model within the depth of 3 km. According to the results of resistivity model, the location of concealed granite and orebody was determined. Granite is characterized by high resistance and is buried at a depth of about 1.5 km, with the formation of ridge uplift along the fault structure. The low-resistivity orebody is located in the middle Devonian strata at the top of granite, so it is inferred that the orebody was developed from the granite at the bottom, which indicates that granite has an obvious ore-controlling effect. According to the zonal characteristics of copper in the near place and tin in the distant place as well as anomalies of metallic elements in the Dachang ore district, it is most possible to find skarn type Zn-Cu deposits and Sb-W deposits. The research shows that, in the late Cretaceous period, the magmatic hydrothermal fluids of the middle and lower crust together with a small amount of upper mantle rose to the shallow Devonian strata of the crust along the basement fault in the NW direction, and then formed mineralization with surrounding rocks through crystallization differentiation.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

In this paper, a simple method for normalization of geochemical data is described. It can be used to reduce the differences between different analytical batches and normalize the data from different areas which have different background values. The method lies in using the ratio of the original analytical value to mean or median value in the batch multiplied by a reference value. The transfer value is given the name apparent content. Two examples are given in this paper to illustrate the details of adjusting the differences.

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.

Based on the systematic collection of information of rare earth element (REE) deposits in North China, this paper analyzes the current situation of REE resources and the temporal-spatial distribution regulation of REE deposits in North China.The mineralization types of the REE deposits in North China mainly include sedimentary and metamorphic type, igneous carbonate magma type, magmatic hydrothermal type, pegmatite type, andion-adsorption type. Given thegeotectonic locations and ore-controlling factorsof REE deposits in North China, the geodynamic background favorable for the formation of the REE deposits includes the ancient metamorphic basement, Archean-Paleoproterozoic rift zones on continental margins, Middle Proterozoic rift zoneson continental margins, and Yanshanian active continental margins in coastal areas of the West Pacific. Thetectonic-sedimentary-magmatic prospecting favorable conditions include volcanic-sedimentary events during the early development of regional deep faults and geosynclines and the magmatic activitiesof alkaline syenitesand alkaline granites. Meanwhile, the geochemical background favorable for REE mineralization consists of high precipitation amount, alluvial plains, and brown soil distribution areas.

Due to the difference of the physical and chemical properties between the normal paraffin and the isoalkane which have the same molecular weight,they are affected by the physical and chemical property of soil substrate and other external environmental factors and are hence likely to have some differentiation effects during migration,rendering their distribution in space characterized by some signature and regularity.Isomerization rate indicators φ_iC4 /φ_nC4 and φ_iC5 /φ_nC5 can expose to some extent the characteristics and regularity.With the isomerization rate indicators φ_iC4 /φ_nC4 and φ_iC5 /φ_nC5 ,we can determine organic maturity,path and direction of light hydrocarbon migration and light hydrocarbon generating environment,and study biochemical degradation of light hydrocarbon.

The construction of three-dimensional visualization models in key urban areas is important for multidisciplinary data integration and intuitive presentation of spatial stratigraphic distribution.However,existing models face limitations in integrated geological-geophysical interpretation and concrete visualization of results.In response to this,this study established a 3D visualization model based on comprehensive geophysical data,specifically including a 3D structural model and a 3D velocity model for the Xiong'an core area down to 5 km depth.It revealed the correspondence between the 3D S-wave velocity distribution and the spatial morphology of strata,and validated the structural framework of alternating uplifts and depressions.To be specific,within the depth range of 0~1 km,the lateral homogeneity of S-wave velocity reflects the stable sedimentary characteristics of Quaternary and Neogene strata.Between 1 km and 2.2 km,the velocity zoning is unclear,primarily due to fracture development in the Jixianian geothermal reservoir,which leads to a reduction in S-wave velocity.Below 2.2 km,the significant velocity contrast between the Xushui Depression and the Rongcheng Uplift is mainly attributed to lithological differences and unconformable contacts.The construction of the 3D velocity model helps overcome the limitations of sparse geological data and reveals the subsurface 3D structures in the Xiong'an core area from a physical property perspective.

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.

Being one of the effective geophysical investigation techniques in engineering and environment,electromagnetic (EM) survey has been well developed in these years. New EM instruments have been continually introduced into underground tube detection, underground water pollution monitoring and subsurface building detection and evaluation. With the purpose of filling in the blank area where the traditional EM methods and the ground penetrating radar (GPR) can not be applied effectively, frequency domain electromagnetic (FEM) instruments make use of frequency bands, in which the diffusion and displacement currents cannot be ignored, and the bit stream transmit technique. Time domain electromagnetic (TEM) instruments are shifted to the very early time of the off time electromagnetic responses. The detection resolution and efficiency can be improved by the new EM instruments. The electromagnetic integrated demonstration (EMID) at the Idaho National Engineering Laboratory Cold Test Pit in USA shows the present status and development trend of the modern EM instrumentation.

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.

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.

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.

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 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.