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.

In order to study the ore-forming material source and ore-forming age of the Liuying fluorite deposit, the authors tested and analyzed the REE of 11 samples of rocks and ores, and determined the mineralization age of fluorite by Sm-Nd method. The results show that the chondrite-normalized REE patterns of wall rocks (marble+mica quartz schist), fluorite ore and Niuxinshan biotite monzogranite all have a rightly-dipping trend, but the distribution curves and statistical values of different parameters of fluorite ore and biotite monzogranite are closer to each other, indicating that they have obvious genetic relationship.The metallogenic age of fluorite is 141 Ma and the values of εNd(t) are negative, which shows that the main metallogenic epoch is early Cretaceous and the crust source characteristics are obvious. The metallogenic age of fluorite ore is basically consistent with that of SHRIMP zircon U-Pb age of Niuxinshan biotite monzogranite (132.4~138.4 Ma), suggesting that there is a close relationship between them, and the material sources should be consistent or similar.

Tomb of Wei Concubine is the nearest to Zhao mausoleum and the highest level in all the Tomb in Zhao Mausoleum,as also, it is the only construction tomb in Mountain of the Tang Dynasty that has been compouded,so,it is improtant to research and protect Tang-dynasty mausoleum.We survey the tomb of the Wei concubine with uav lidar survey, ground high-precision gravity and magnetic survey, high-density electrical survey, GPR and soil radon gas survey for evaluating the results. Ground high precision gravity and magnetic survey combined with soil radon measurement can effectively delineate the plane position of underground place. The high density electric method accurately delineates the space position under ground. The GPR has clearly detected the fine structure of the tomb with a resolution of up to sub-meter level, These resoults provide valuable information for exploration of Zhao Mausoleum’s underground palace in the future.

The northeastern margin of the Linyi uplift is located at the eastern end of the Luxi Block and immediately adjacent to the Yishu fault in the east. The main structural framework of the study area is controlled by the NE-trending Tangwu-Gegou fault and the NW-trending Mengshan fault. Covered by the Cenozoic sediments, the boundaries of main tectonic units in the study area are almost all concealed, and it is necessary to further investigate the change in the strike of the eastern end of the Mengshan fault as well as the distribution of the angular unconformity along the northern boundary of the Linyi uplift. Using the latest 1:50,000 high-precision gravity data, this study mainly investigated the positions and intersection relationships of the boundaries of tectonic units based on the qualitative analysis of gravity field, the interpretation of multiple gravity potential field conversion, and the division scheme of geotectonic units in Shandong Province. The analysis results are as follows. The Mengshan fault at the junction of the Mengshan uplift and the Pingyi sag transitions from the NW trending to nearly-EW trending in the east of Bancheng Town, significantly cuts the NE-trending Tangwu-Gegou fault, and shows a NW-trending turn to the east again. The angular unconformity at the junction of the Linyi uplift and the Pingyi sag neither ends in the Mengshan fault in the north nor turns southward but extends to the Tangwu-Gegou fault in the east. This unconformity also controls the southern boundary of the Pingyi sag, making the NW-trending banded gravity anomalies of the sag turn eastward. Consequently, the boot-shaped low-value gravity anomalies were formed in the study area. Based on the high-precision gravity boundary identification, this study determined the fault system and tectonic division of the northeastern margin of the Linyi uplift, providing high-precision gravity data for the basic geological study in the study area and laying a good foundation for further mineral geological survey.

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.

The existing geological data show that there are several buried faults in the main urban area of Chengdu. However, the specific location and distribution of these faults are still unclear, which poses great security risks to the comprehensive and scientific exploitation and utilization of underground space resources and the optimization of urban construction planning and layout in Chengdu. In view of such a situation, four geophysical methods, namely, micromotion survey, high-density electrical method, transient electromagnetic method and soil radon measurement, were used in this paper to comprehensively explore the buried Baojiangqiao fault in the work area. The integrated geophysical prospecting methods not only identified the stratigraphic structure along the survey line, but also obtained the location, property, attitude and scale of the buried Baojiangqiao fault. This work indicates that the integrated geophysical prospecting methods can achieve better results in the exploration of urban buried fault.

Shale gas reservoirs have the characteristics of low porosity and low permeability.The large-scale exploitation of shale gas requires the reconstruction of shale reservoirs through horizontal well fracturing technology.Available data indicate that,when the horizontal shale gas well azimuth is approximately perpendicular to the maximum horizontal principal stress,and the coefficient of difference in horizontal in-situ stress is small,it is favorable for fracturing to form network fractures and improve the effect of reservoir reconstruction.An in-situ stress prediction model was established for the Nanchuan area.On the basis of detailed 3D seismic interpretation and 3D seismic prestack inversion,the regional adaptive parameters were selected by using well data simulation,and the 3D simulation of the in-situ stress field was performed to predict the direction of the maximum horizontal principal stress,the direction of the minimum horizontal principal stress and the coefficient of in-situ stress difference.Through an analysis of the regional stress mechanism and the interpretation of the induced joint and the analysis of the application,the reliability of the in-situ seismic prediction results was verified,and the important role of in-situ stress analysis in shale gas development was proved.

Anqiu-Juxian fault in the Tanlu fault zone is in a concealed state in the Juxian basin.Geophysical data in the basin is very insufficient,and the distribution and spatial geometric characteristics of the fault are not clear.In view of such a situation,the buried faults in the basin were detected by shallow seismic reflection detection,and the distribution characteristics of Anqiu-Juxian fault in the basin were preliminarily discussed and analyzed in combination with the study of Zheng Chuanbei and other research results.The results show that the Anqiu-Juxian fault is located in the Quaternary sediments of Juxian basin,with relatively shallow burial depth.The fault is characterized by compressional thrust and positive fault in some sections.The shallow seismic reflection profile shows the new geophysical evidence of Anqiu-Juxian fault in Juxian basin and provides geophysical reference for the overall evaluation of the fault.

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

Jiaodong area is one of the major gold producing areas in China, and the deep prospecting in this area is to seek deep breakthroughs and blind spots at present. With the gold concentration area in Jincheng Town in Laizhou City and Ershilidian Town in Haiyang City as an example and based on the prediction and assessment theory and method of deep gold resources, this study summarizes the deep spatial characteristics and relationships of the Archaeozoic-Mesozoic intrusive rocks, Precambrian metamorphic basement, and the strata in Jiaolai Basin in the area and the deep morphology and characteristics of major ore-controlling structures in the area. To this end, section measurement was carried out using the integrated geophysical exploration of high-precision gravity survey, high-precision magnetic survey, and magnetotelluric sounding. Meanwhile, the obtained gravity, magnetic, and resistivity data were comprehensively researched and analyzed in combination with previous results. This study will provide a basis for the late prospecting prediction of deep gold deposits and related researches of the area.

In order to find out the occurrence status of geothermal resources in Huangniqiao area, Ninghua County, Sanming City, Fujian Province, the authors carried out geothermal exploration work in this area by using the audio frequency magnetotelluric method (AMT). Based on the analysis of the characteristics of layer structure and lithology in the work area, the fault structure distribution in the area was inferred and, according to the fault distribution characteristics, one optimized geothermal abnormal target area was delineated. Drilling shows that the well bore water-bearing formation is in good agreement with the low resistivity anomaly of AMT two-dimensional inversion. On the basis of verification, the spatial distribution model of faults in the area was constructed, and four potential fault type thermal storage areas were inferred according to AMT inversion results and fault distribution characteristics. The overall research results show that AMT method is feasible and effective for geothermal resource exploration, which can provide important reference value for the deployment of geothermal exploration in similar areas in the future.

The Silurian Longmaxi Formation shale in the south of Sichuan Basin has the geological characteristics of large burial depth (more than 3000 meters), thin thickness of high-quality shale section,rapid change of formation dip angle,and development of micro structure and micro fracture.It is difficult for the traditional geosteering technology to accurately identify the target location of the longitudinal sweet spot.During the drilling process of horizontal section,there is a high risk of target miss target and formation production.The 3D seismic data can provide guidance for sidetracking and target entry of horizontal wells and guide horizontal drilling.Taking the seismic tracking of shale gas horizontal wells in the complex area of southern Sichuan Basin as an example,this paper introduces a new idea of horizontal well seismic guidance technology based on anisotropic prestack depth migration three-dimensional data volume.Based on high-precision imaging data and considering regional velocity field background,geological constraint velocity modeling ensures accurate target and,at the same time,real-time anisotropic depth migration of target block can be carried out.In addition,real-time seismic tracking during drilling can effectively help drilling geosteering and provide early warning and adjustment scheme for drilling engineering.The actual drilling shows that the seismic steering technology for horizontal wells in shale gas complex structural areas can effectively improve the effective reservoir drilling rate of horizontal wells for development and engineering needs.

Airborne geophysical techniques represent a cost-effective way for obtaining insights into the crustal geology of the Antarctic. Based on the analysis of the history of Antarctic airbrone geophysical survey and development of facilities and fly-platform applied in the survey, this paper gives a review of the leading scientific application topic of airborne geophysical data i.e.,the crustal structure of Antarctica,the reconstruction and restoration of ancient terrains, magmatism and volcanism identification,and the interaction between Antarctica Ice Shelf and bed rock, which shows that airborne geophysical survey provides effective technical support for Antarctica geosciences research.Our research shows that there is still a blank area for geophysical survey. Based on out review, the combination of airborne magnetic, airborne gravity and ice radar data has provide a new solution to the interaction study of Antarctic Ice shelf and bedrock.

In marine oil and gas exploration,for the purpose of accurately acquiring the high-precision and high-resolution reflection information of the exploration target and realizing more delicate imaging,broadband acquisition and processing technology of marine seismic has been greatly innovated and developed in recent years.In this paper,the generation mechanism of ghost wave,the classification and characteristics of ghost wave and its manifestation in actual seismic data are studied.The high-resolution radon transform in frequency domain is used as the main processing method to attenuate ghost wave in a broad-band data of a straight slant cable.After the ghost wave suppression processing,the source ghost wave and cable ghost wave of seismic data have been greatly attenuated,and the notch energy has been significantly enhanced.The broadband processing not only broadens the low-frequency component of seismic data,but also broadens the high-frequency component of seismic data;especially,the low-frequency component energy has been significantly enhanced.This method has achieved good results in the application of marine seismic data.

The eastern region of Sichuan basin is located between Huaying Mountain and Qiyaodan Mountain. After multiple periods of complex structural superposition and transformation, high and steep tectonic belts and faults were formed. It is difficult to detect and distinguish hidden faults in the high and steep tectonic belts in geophysical exploration. Based on the forward and inverse simulation results of gravity, magnetic and electric detection methods, the authors have reached the conclusion that buried faults in high and steep fault folds can be detected and recognized. Combined with the practical application effect of gravity, magnetic and electric integrated geophysical prospecting methods in high and steep fault folds in eastern Sichuan, the authors summarized the abnormal morphology and abnormal characteristics of buried faults . At the same time, the experimental results of field data acquisition interference suppression and the forward inversion processing method of fault fracture zone anomalies were also summarized. The results obtained by the authors provide a reference basis and experience accumulation for geological exploration in eastern Sichuan.

Surface wave dispersion curve inversion is an important geophysical method for obtaining the velocity and thickness distribution of underground shear wave.Conventional linear inversion methods,such as iterative least squares,relying on the initial model and multiple solution,are easy to fall into local minimum and low inversion accuracy.The stochastic inversion method based on Bayesian theory is a nonlinear inversion method which can integrate prior information.This method does not need initial model,only uses prior information to sample the model randomly,and selects and accepts the appropriate inversion model according to the probability distribution.It achieves the accurate estimation of the detail information.In this paper,the authors present a Bayesian Markov Monte Carlo (MCMC) stochastic inversion method based on GPR data constraints to invert the Rayleigh-waves dispersion curve.In the inversion process,by randomly changing the model parameters and calculating the likelihood function of the dispersion curve and the actual dispersion curve,researchers can choose whether to accept the new model parameters,repeat this process continuously,and finally get the best fitting result with the actual dispersion curve and the posterior probability density distribution of the VS solution.The typical numerical model test and field seismic data demonstrate that,compared with the conventional unconstrained stochastic inversion,the proposed method can effectively reduce the multiple solution and improve the efficiency and accuracy.

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

The Haiyu gold deposit, as a superlarge gold deposit with gold reserves of 470 t and average grade of 4.30×10^-6, is a typical Jiaojia-type gold deposit. The authors carried out the rock geochemical survey by the samples from drillholes, and detected the enrichment of Au, Cu, Pb, Zn, Ag, As, Sb, Cd, Bi, S and Fe₂O₃ and the depletion of Na₂O, Ba and Sr in the ore-hosting tectonic alteration zone. The authors systematically summarized the geochemical marks used for exploration. The enrichment of S and Au, or called the positive S and Au anomalies, is the typical geochemical mark of the source rock. The enrichment of S, Au, Ag and Bi and the depletion of Na₂O and CaO are typical geochemical marks of the tectonic alteration zone. Based on the above elements and their anomalies, the authors constructed the ore-induced anomaly model of the Haiyu gold deposit, which provides a useful reference for the exploration of the peripheral and deep-seated gold deposits. It is proposed that the main gold orebodies of the ore-forming zone of the sea field may be along ZK2403, ZK3008, and ZK3814 boreholes spread in NEE direction.

The Chahe deposit is the largest tin deposit in Sichuan Province. In order to gain a prospecting breakthrough, the authors conducted 1:50 000 stream sediment survey, studied the characteristics of element combination of this area by feature analysis and factor analysis of the measuring results. The results show that the three main ore-forming element groups of Ag-Pb-Zn, Bi-F-W-Sn and Cu-Ni have similar enrichment rules, in which the enrichment regularities of W, Sn and other medium and high temperature elements are extremely significant, and the overlapping features of the spatial distribution of the element anomalies are good.The lower limit values were determined by methods of cumulative frequency and iteration. The authors compiled the element anomaly maps and delineated nine comprehensive anomalies. By comprehensive evaluation of the anomalies, the authors consider that the Chahe and Fangjia composite anomalies are the prospective areas. The authors analyzed the geological condition for mineralization, carried out mineral inspection, and discovered a new skarn type tungsten-tin vein in the Chahe prospective area and more than ten new quartz-vein type tungsten veins in the Fangjia prospective area. The Fangjia prospective area, with a certain degree of similarity in geological characteristics with the "five-story+basement" prospecting model for tungsten deposits, has a favorite prospect in the search for polymetallic deposits such as tungsten, copper, lead and molybdenum.

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

Mianluening area is one of the most complex areas of geological structure around the Yangtze plate. Based on the comparative study of the high magnetic anomaly zone to the west of Baiquesi basic complex, the regional gravity anomaly gradient zone and the geochemical anomalies of Fe, V, Ti and other elements, combined with the geochemical characteristics of the overflow phase basalts distributed along the anomaly zone, it is inferred that there may be a larger hidden fault in the deep part of the NNE-trending shallow faults interpreted by surface remote sensing. This hidden deep fault may have provide an important channel for the mantle-derived magmatic activity in the context of post arc cracking in Mianluening area in the Neoproterozoic. On the one hand, the Baiquesi basic complex and igneous carbonatite were formed by the intrusion of the plutonic magma; on the other hand, the belt like overflow phase basalt rich in magnetite was formed by the fissure type volcanic eruption. This finding is of great significance for the study of Neoproterozoic tectonic setting and mantle-derived magmatic mineralization in Mianluening area.

The forward modeling is an effective way to study the characteristics of transient electromagnetic (TEM) responses. The high precision and fast 3D forward modeling technology is a hot spot in the study of TEM forward modeling. The multiphysics module in ANSYS software is suitable for the forward modeling of TEM. In this paper, the application method of ANSYS software in TEM 3D forward modeling is introduced by some model examples, including the preprocessing, loading, solution setting and post-processing. The numerical results show that the simulation of TEM forward modeling by using ANSYS software has high accuracy. The TEM forward modeling using ANSYS can improve the efficiency of forward simulation calculation and provide a strong support for analyzing and understanding the characteristics of TEM response.

In order to find out the stratigraphic structure and groundwater pollution in the ore concentration area of Guyang County, Baotou City, it is necessary to carry out hydrogeological drilling around typical mines in the ore concentration area. In this paper, according to different types of groundwater-finding targets and the advantages of different measuring devices in resolution and signal-to-noise ratio, the multielectrode resistivity method was employed to study and analyze the electrical structure characteristics and well forming pattern of groundwater around south concentrator of Wengeqi iron deposit, Hongchang concentrator and Shangshierfenzi gold deposit. The result shows that comprehensive analysis of the hydrogeological conditions of the study area and utilization of different arrays of multielectrode resistivity method seem to be effective technical means for carrying out water resources investigation, which can achieve the target, reduce the multi-solution of geophysical inversion and interpretation, greatly improve the efficiency of searching for groundwater resources by using single geophysical method and provide a technical basis for water exploration and well determination in the ore concentration area of Guyang County, Baotou City.

As it is difficult to collect the weathering stream sediments of bedrock in the loess overburden area,the effect of regional geochemical exploration is often not ideal; therefore, regional geochemical exploration work has not been carried out in many loess overburden areasof China. In this paper, the deep-penetrating geochemistry method was used to carry out the experimental study of geochemical prospecting techniques for concealed deposits in the loess overburden area in the Zhonghedi silver-lead-zinc polymetallic deposit in Xiaoshan, Henan Province. The results of fine-grained soil prospecting method and metal mobile extraction measurement show that both methods can well indicate the anomalies of underlying polymetallic orebodies in the loess overburden area and, at the same time, the mobile extraction method further enhances the abnormal indication of ore-forming elements to the orebody, so both methods can be used as effective means in search for concealed polymetallic deposits in the loess overburden area.

The formation of natural selenium-rich soiltends to be controlled by the parent materials. Spatially, it is closely related to the distribution areas of selenium-rich rocks such as black rock series, coal-bearing rock series, carbonaceous mudstones (shales), argillaceous limestones, and volcanic rocks. Selenium-rich soil of different genetic types greatly differs in development suitability. However,agenetic classification scheme of natural selenium-rich soil is yet to be developed. This paper sorted out the genesis of natural selenium-rich soil and divided it into three categories and 10 subclasses according to the major controlling factor of selenium source in soil (parent materials) based on existing classification schemes. Then it briefly reviewed the primary characteristics and development suitability of selenium-rich soils of four major subclasses, i.e., black rock series, coal-bearing rock series, volcanic rocks, and epimetamorphic rocks.Based on this, this study proposed assessment indices of the development suitability of natural selenium-rich soil.

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.

With the gradual acceleration of the construction of Yinchuan metropolitan area, especially the further expansion of Ningdong national energy and chemical base, the Yinchuan Plain urban agglomeration has been encountered with severe environmental quality problems, especially air quality problems. Therefore, intensifying the development and utilization of clean energy, optimizing the energy utilization structure in the region and reducing harmful gas emissions are one of the effective ways to improve air quality. Based on the regional geological structure and geothermal geological conditions on the eastern margin of Yinchuan Basin, the authors used regional gravity, magnetic, electrical, seismic and drilling data to focus on the analysis of three important geothermal enrichments in deep heat sources, heat conduction channels and reservoir caps. The geothermal accumulation model on the eastern margin of Yinchuan Basin was constructed, which lays a solid research foundation for the subsequent development and utilization of geothermal resources.

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.

Great progress has been made in the formation mechanisms of surface characteristics of gas microseepagesince the start of the 21st century, which is significant for oil-gas exploration. The microseepage in petroliferous basins is dominated by methane, which migrates nearly vertically from source rocks or reservoirs toward ground surface. The chemical, physical, and biological variation characteristics produced on the ground surface approximately reflect the oil reservoirs underground. Therefore, the methane microseepage is an objective and important part of the petroleum seepage system and has replaced microseepage as the most effective window for the tracing of underground reservoirs on the ground surface at present. Methane microseepage can be directly monitored on ground surface and in water and atmosphere, and the component concentrations and isotopic composition of methane-bearing hydrocarbon gases serve as the first-hand important data for the assessment of underground oil and gas. The data indirectly monitored mainly source from microorganisms, vegetation, minerals, radioactivity, and magnetism on the ground surface. Similar to the geochemical exploration data directly obtained, these abnormal data canbe distinguished from the background values of the ground surface far away from the oil reservoirs, and the distribution areas of the anomalies will become important targets of favorable exploration areas. It will play an increasingly important role in the future integrated oil and gas explorationto gain in-depth understanding of methane microseepage mechanisms, avoid single monitoring method and one-sided understanding, transform ideas to adoptsurface integrated monitoring methods, and establish new mathematical analysis systems.

Influenced by the difficulty of exploration and poor seismic quality, the exploration of oil-gas resources in the southwest of Tarim Basin has not achieved a substantial breakthrough after decades of work. Based on the latest high-precision aeromagnetic data obtained in Southwest Tarim Basin in recent years, this paper discusses the geological problems related to oil-gas accumulation, such as basement structure of basin, distribution and characteristics of depressions, main fault structures and their controlling rules for oil-gas migration and accumulation, local anomalies and favorable local structures of oil-gas as well as their distribution characteristics. The results of the study can provide important reference for the further strategic selection of oil-gas exploration and deep resource evaluation in Southwest Tarim Basin.

Deep learning is an extension of the artificial neural network algorithm, which has a good approximation ability for complex functions. This paper introduces this means for the calculation of transient electromagnetic apparent resistivity. First, a 5-layer deep neural network is established with a single mapping relationship between the normalized induced electromotive force and the transient field parameters. By analyzing the error conditions trained by different numbers of neurons in a single hidden layer, the hidden layers of the 5-layer deep neural network are determined. The number of layered neurons is 13,8,5,8,13. The training algorithm chooses the improved Nadam algorithm with adaptive learning rate, which can speed up the training process. The trained deep neural network model is simulated and verified by a typical electrical model, and it is found that it has a good response to different geoelectric models, which proves the feasibility of calculating apparent resistivity based on deep learning put forward in this paper. The actual application results show that the trained deep neural network model can quickly and accurately calculate the apparent resistivity, and its effectiveness is verified by drilling.

This study summarized the progress and major application performance of gravity and magnetic techniques for onshore hydrocarbon exploration in China in recent years.By combining the research results of the authors,this study elucidated the new progress made in the gravity and magnetic techniques for hydrocarbon exploration from the prospect of acquisition,processing,interpretation,and application and sorted the application performance of these techniques in key fields including deep targets,complex areas,and volcanic rocks.Moreover,this study future analyzed the demand for the gravity and magnetic techniques for hydrocarbon exploration.By combining the new trends of gravity and magnetic exploration techniques at home and abroad,this study proposed the development direction and application prospect of gravity and magnetic techniques for oil and gas in deep strata and igneous rocks in complex areas.The results of this study show that significant progress has been made in gravity and magnetic exploration techniques,which play an important role in supporting the current hydrocarbon exploration.It is expected to develop high-precision and high-density gravity and magnetic exploration techniques and gravity-gravity-electricity-seismic collaborative innovation techniques.

The Jiama mining area in Tibet is one of the most important large deposits in the eastern Gangdise porphyry copper belt. There are many kinds of rocks, and the physical properties of different strata and intrusive rocks are complex and diverse. In the past, due to the lack of enough attention to the physical properties of rocks, the types of rock determination were not comprehensive enough, and there was a lack of systematic and complete understanding of the physical properties of rocks in the Jiama mining area. On the basis of an analysis of rock physical property data in the past and through the physical property measurement and statistical analysis of core samples from six typical boreholes in the Jiama mining area, the characteristics of rock density, magnetism, resistivity and polarizability in the mining area were summarized, and the rock geological geophysical model of the mining area was established, which provides a reliable basis for the subsequent geophysical work in the mining area. Secondly, the rock electrical parameters were used to correct the static effect measuring points on the magnetotelluric sounding profile in the mining area so as to provide the basis for the magnetotelluric sounding profile interpretation and guide the magnetotelluric data processing and interpretation in the mining area. Through the comparison and verification of drilling data, good exploration results were achieved.

Danghe Nanshan is one of the important gold metallogenic areas in Gansu Province. A number of important gold deposits have been discovered there, such as Jiagongtai, Heicigou and Langchagou, suggesting that the metallogenic conditions are very favorable. However, due to the special geochemical landscape of this area, the peripheral prospecting effect is not good. When carrying out the 1:50 000 mineral prospect survey project in Heidaban-Danghe Nanshan area and aiming at the low and gentle anomalies in the area, the authors introduced the 1:10 000 tectono-geochemical debris survey method into the gold prospecting work for the first time, and analyzed the geochemical characteristics and element combination characteristics in this area. Combined with the metallogenic geological background, 13 comprehensive geochemical anomalies were delineated, and it was found that the main metallogenic elements Au, Pb and Pb and exploration elements As and Sb are intensively enriched in favorable structural positions. Through trenching, 6 new gold mineralization zones were discovered and 15 gold orebodies were delineated. This method was further applied to the gold prospecting in adjacent areas, with good prospecting results achieved. The successful application of this method is of great significance for prospecting in the geochemical landscape area of shallow covered Alpine desert.

The Guanzixia M exploration area in Huining County is located in the hilly and gully area of the Loess Plateau,which has a good prospect of prospecting for graphite ore. Firstly, graphite ore metallogenic conditions in the exploration area are analyzed. Then, the geophysical work is carried out in the favorable area of graphite mineralization. Adopting the dual frequency induced polarization intermediate gradient to measure the apparent amplitude frequency, apparent resistivity and the natural electric field adopted to measure natural,the two methods are used to delineate graphite mineralization anomalies,which are characterized by high amplitude frequency, low apparent resistivity and negative anomaly of natural potential. On this basis, the induced polarization sounding is used to find out the spatial distribution characteristics of mineralized anomalous bodies, and provides evidence for drilling through various methods. It has been verified by drilling that 2 layers of graphite ore are drilled, and obtained good exploration results.

Urban land subsidence is liable to induce ground fractures or even collapse,thus causing safety accidents.However,traditional geophysical methods cannot be applied in cities due to the strong human interference and high requirements for safety and environmental protection in the urban environment.The microtremor survey method is a passive,efficient,and environment-friendly geophysical method and it can be used to detect the underground geological conditions in the urban environment with strong interference.Taking Xiegang Primary School in Hefei City as the research site,this paper focuses on the applicability and effectiveness of the microtremor survey method in detecting the causes of land subsidence.Based on the microtremor survey data collected,the dispersion curve was extracted using the F-K method and then the underground shear wave velocity structure was obtained through inversion,thus revealing the underground geological conditions.Finally,verification was conducted through drilling.The results show that the microtremor survey is an effective geophysical method for detecting the information such as the position and scale of underground unconsolidated soil,and thus the secondary accidents in subsidence areas can be eliminated.

With Xiangshan South-Dadiantang area of the Ningwu volcanic basin as an example, the authors used the methods of geology and unmanned helicopter aeromagnetic to explore the prospecting work in the deep and peripheral parts of the old mine. Comprehensive analysis and fine inversion of aeromagnetic anomalies were conducted to determine the location of the borehole. All the drill holes intersected ores in the depth of the old mine, which proves the effectiveness of this method. The result also provides a reference for the rapid and effective development of prospecting work in the deep and peripheral areas of old mines in areas with similar working conditions in the future.

As an important part of the Tianshan metallogenic belt in Central Asia, Kyrgyzstan boasts rich mineral resources and completely types of mineral resources. The national scale (1∶1 000 000) geochemical mapping of Kyrgyzstan covers an area of about 170 000 km² across the country and the analyses and tests of 69 elements. It has filled in the blank of national geochemical mapping in Kyrgyzstan and will provide basic geochemical data for studies on basic geology, mineral development, environmental protection, and agricultural production inthe country. According to the regional geologic and structural evolution and geochemical background, the study area is divided into five structural geochemical regions. According to the geological background and the statistical analysis of geochemical parameters of major metallogenic elements, it is considered that Kyrgyzstan is a metallogenic favorable region of Au, Cu, Pb, Sb, Sn, W, and Ag, with notably distributed geochemical anomalies. In detail, the northern Tianshan Mountain shows high anomalies of Au, Cu, Pb, Zn, Ag, Be, and As. The middle Tianshan Mountaincan be divided into the eastern and western parts with the Fergana fault as the boundary. Among them, the western part is rich in Au, Cu, Cr, Mo, and Co, while the eastern part is rich in Au, W, Sn, Co, Cr, and Ni. As for the southern Tianshan Mountain, the western part is characterized by the concentrated distribution of Cu, Co, Cr, Ni, Au, As, Sb,and Hg, while the eastern part is characterized by the distribution of W, Sn, and Bi associations. The analytical results of metallogenic significance are as follows.The Chattkar area in middle Tianshan Mountain is considered the area with the highest prospecting potential in Kyrgyzstan. It has enormous potential for the prospecting of Cu, Pb, Au, and W. It is followed by the Zarejaz area in the eastern part of the southern Tianshan Mountain, which also has great prospecting potential and is highly favorable forthe prospecting of Au, CU, W, and Sn. Besides, the western part of the southern Tianshan Mountain and the Talas-Narun area also enjoygood prospecting potential and are prospecting favorable areas of gold, copper, lead, and zinc polymetallic deposits.

The forward modeling of a 3D mesh model is the basis of gravity data inversion. High precision and high efficiency forward modeling is helpful to the improvement of the quality of inversion interpretation. In order to solve the problem of high precision and high efficiency gravity forward modeling based on a large-scale surface observation area, this paper presents the gravity anomaly forward modeling method and parallel algorithm of a 3D Tesseroid mesh model in the spherical coordinate system. The forward modeling uses the improved Gauss-Legendre Quadrature integration method to realize the high-precision gravity anomaly calculation based on a large-scale surface observation area, and also uses the MATLAB task parallel algorithm based on OpenMP to realize the high-efficiency forward modeling. The test on the 3D theoretical model and the Eastern China lithospheric model has verified the validity of the proposed method. This method can provide technical support for efficient large-scale gravity field simulation and 3D inversion.

Due to the influence of the artificial boundary condition, when the conventional finite element method is used to carry out the forward simulation of the three-dimensional geophysical field in a limited space, local abnormal distortion may occur, which affects the accuracy of the numerical simulation. This problem is usually solved by expanding the edge, but this requires a larger range, which greatly increases the computational cost and affects the efficiency of forward simulation. In this paper, on the basis of COMSOL Multiphysics software, infinite elements are set on the external boundary to replace the traditional boundary conditions so as to reduce the calculation area. Compared with the traditional finite element method, the finite element infinite element coupling method, by setting the isolated sphere and the combined body model and considering the conditions of demagnetization, remanence and surface undulation, can effectively overcome the boundary effect, improve the calculation accuracy and reduce the amount of calculation, thus improving the forward numerical simulation efficiency of the finite element method.

Gas content is one of the main parameters to evaluate whether shale gas can be enriched to obtain high-yield.The higher the gas content,the more favorable for shale gas wells to obtain high-yield.Traditional gas content seismic prediction methods are based on single-attribute,multi-attribute linear fitting or simple neural networks,and have low accuracy.The gas content prediction method is based on deep neural network.Through optimizing seismic attributes,optimizing the solution method and choosing the appropriate number of hidden layers,the number of neurons,and the number of iterations,a prediction model can be established to predict the gas content of shale,thus effectively improving the prediction accuracy of shale gas content and providing support for the geological evaluation of shale gas research areas and the deployment of shale gas horizontal wells.

As one of the important regional faults in northern Ningxia, the Yellow River fault has controlled the formation and evolution of Yinchuan Basin. This fault is one of the inevitable key points for studying the law of seismic activity and geothermal resource enrichment in Yinchuan plain. At present, the study of the Yellow River fault is very insufficient, and the work is mainly concentrated on surface survey with shallow geophysical exploration in some areas. In this paper, the authors used geological outcrop data as clues and, based on regional 1:200000 gravity data, used advanced geophysical data processing techniques such as wavelet demarcation and oblique derivative to clearly depict the phenomenon that the Yellow River fault has obvious characteristics of "flying geese" plane distribution. The fault is divided into four sub-segments: Lingwu section, Linhe section, Yueyahu section and Lihe section. The CSAMT data of Linhe section and Lingwu section reveal that the main fault and its secondary faults of the Yellow River descend gradually from east to west, i.e., "staircase", with obvious "grading" characteristics. The undercut depth of the Yellow River main fault reaches the upper crust, and the combination of the secondary-scale faults on the profile exhibits a typical "broom" shape. The "seat-like" space of "upward steep, moderately gentle, and downward steep" of each fault is obviously present. Compared with the existing research results, it is found that there are three differences between them, i.e., spreading characteristics, spreading position, and spreading relationship.

Aiming at tackling the current shortcomings of wide field electromagnetic method data processing software such as low integration, cumbersome operation and inability to manage data in a unified manner, the authors developed wide field electromagnetic method data processing and interpretation software. The software adopts client-server architecture and modular design. The project management module developed based on MySQL database can realize the automatic storage and management of project data. The data processing module of wide field electromagnetic method developed by the scientific computing library based on Python can meet the data processing requirements. Based on visualization and interactive operation, this software can greatly simplify the operation process and improve the efficiency of data processing. This software was applied to actual projects and, as a result, large quantities of data were processed, and good results were achieved.

In the Middle-Lower Yangtze River metallogenic belt, the possibility of the development of copper-gold mineralization similar to things of the fault-uplift area in the depth of volcanic basin has attracted extensive attention. Based on the geophysical profile through the Tongling fault-uplift area and Fanchang volcanic basin and using integrated geophysical exploration methods, the authors identified the deep geological structure, rock and ore-controlling structure and the distribution of intrusions. The comparative study shows that the lithology, height and distribution of intrusions are different in Tongling and Fanchang area, and the intrusions in Fanchang is more felsic and shallow than those in Tongling. The faults in Tongling area only control the shallow location of intrusions, while the boundary faults in Fanchang basin are the channels for magma rising. The intrusion in Tongling area is characterized by "one mother and multiple offspring" and different intrusive branches or strains derived from the same magma chamber, which directly proves that different types of intrusive rocks in Tongling area are the products of the evolution of the same magma source region, and different degrees of evolution may be one of the reasons for their different kinds of mineralization. In this study, the authors used integrated geophysical exploration methods to discuss the difference of diagenesis and mineralization between Tongling fault-uplift area and Fanchang volcanic basin and explain the reason why only small iron mineralization exists in Fanchang region while large copper (-gold) deposit occurs in Tongling region. In addition, large-scale intrusion of granitic magma in the depth of Fanchang region indicates that there is no "second Tongling" in the depth of the Fanchang volcanic basin. These results further deepen the understanding of the regularity of copper and iron mineralization in the Middle and Lower Yangtze River metallogenic belt and provide theoretical support for ore prospecting and exploration in the future.

Seismic wave forward modeling technology is widely used in shallow exploration.This method can combine geological model and seismic model organically to verify and guide the acquisition,processing and interpretation of seismic data.The deep reflection seismic profile detection technology based on the oil reflection seismic technology has been very mature after decades of development and application.But up to now,the application of seismic wave forward modeling in deep reflection seismic profile is very insufficient.In this paper,the deep reflection seismic profile across Sichuan Basin was used to carry out forward modeling.By comparing and fitting the horizon of forward simulation data and actual seismic data,the parameters such as velocity and horizon were constantly modified,and the final depth domain geological model was established,which provides more accurate stratigraphic information such as crustal thickness and Moho depth for structural profile.Through the geological model in depth domain,it is revealed that the angle of Neoproterozoic paleosubduction in the northwest margin of Yangtze plate was about 30 °,and the depth of subduction reached 60 km.

Shallow seismic reflection (SSR) surveys are an indispensable method in the exploration of urban underground space.Their exploration effects are affected by many aspects such as excitation,receiving factors,acquisition parameters,and processing methods,which should be systematically scientifically demonstrated and selected according to geological tasks.Taking an underground space exploration project in Jinan as an example,the authors discussed the method of improving the resolution of SSR surveys.Through the comprehensive analysis of the collected data,a reasonable seismic geological model was established.Based on this model,the forward analysis and illumination analysis were performed using the fluctuation equation of seismic data acquisition parameters,obtaining a high-density two-dimensional seismic observation plan.Meanwhile,high-resolution reflection images were obtained through the study on targeted data processing techniques such as pre-stack denoising,deconvolution,and velocity field optimization.Excellent exploration results have been achieved in the project.This study will provide reliable geophysical exploration data for the construction of the smart city in Jinan,and can serve as references for the implementation of SSR exploration in this area in the future.

With the increasing demand for oil and gas resources,the exploration and development of oil and gas fields have shifted from conventional to unconventional fields,and tight oil and gas reservoirs have become the current and future focus of the exploration and development of unconventional oil and gas.Most of the tight reservoirs in China are continental sediments with poor lateral continuity,strong vertical heterogeneity,complex lithology,and large changes in physical properties.All these make it difficult to effectively characterize the pore structure of tight reservoirs.The pore structure of reservoirs not only affects the occurrence of oil and gas but also seriously restricts the seepage and efficient exploitation of oil and gas.To analyze the pore structure characteristics of tight reservoirs in a targeted manner,this study systematically investigates relevant literature on the assessment methods of pore structure of tight reservoirs and organizes indirect measurement methods such as semi-permeable plate,direct observation methods such as casting thin sections,and digital core method.Moreover,it dissects the logging-based assessment methods of the pore structure of tight reservoirs,explores the applicability,advantages,and disadvantages of these methods,and further proposes the development trend of pore structure study based on the current status.

As oil shale is an important unconventional oil and gas resource,its exploration and development has received increasing attention.Microtremor exploration based on seismic ambient noise is a passive,efficient and low-cost method of seismic exploration,which can be used to image the shear wave velocity of underground medium and can become a potential new exploration method for oil shale more in line with the requirements of "environmental protection".For the first time,the authors applied microtremor method to oil shale exploration based on the spatial cross correlations of common central panel and conducted a study of the identification of oil shale in Songliao Basin.The results show that the geometry of microtremor method can be flexible according to the real situation,the shear wave velocity profile corresponds well with the results of borehole cataloging near the survey line and the main stratum is well divided.The second member of the Nenjiang Formation,which is mainly oil-bearing shale,exhibits low velocity characteristics.

The vibrator has been widely used in petroleum,coal field and other seismic exploration,and the corresponding technical means are relatively mature;nevertheless,there is no reference basis for the parameter selection of middle and shallow seismic exploration with vibrator.In order to study how to obtain high quality data in middle and shallow seismic exploration,the authors carried out a series of "vibrator excitation,high frequency geophone reception" experiments in Xiong'an.Based on a large number of experimental data and using qualitative analysis of original single shot and quantitative analysis of frequency spectrum,this paper systematically discusses the influence of the selection of parameters such as vibration number of vibrator,sweep length,starting frequency,ending frequency,drive level,slope length and natural frequency of geophone on data quality.This paper clarifies the key points and basis of parameter selection,puts forward the concept of high cutoff frequency,and summarizes the strategy of parameter selection for middle and shallow seismic exploration,which provides some reference for the use of vibrator in middle and shallow seismic exploration.

In an open-pit coal mine in Hulun Buir of Inner Mongolia, the main mining coal seams are buried in depths ranging from 39m to 90m. Before coal mine integration, predatory mining has left many mined areas with unknown geological data, and the existence of mined-out areas has brought huge safety hazards to open-pit mining stripping. In order to find out the specific location and connectivity of the underground goaf, the authors used the cross-hole electromagnetic wave CT method to probe into the inside of the goaf in detail, and obtained a lot of real and reliable geophysical data. The analytical result shows that relatively complete rock formation electromagnetic wave absorption coefficient is in the range of 0.44~0.51Nper/m, and no water-filled goaf electromagnetic wave absorption coefficient is in the range of 0.29~0.40 Nper/m. According to the difference of electromagnetic wave absorption coefficient between goaf and surrounding rocks, the authors drew the morphological interpretation map of the goaf, and the results are basically consistent with the drilling data.