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

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.

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.

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

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

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

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

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

The edge depth of geological body plays a crucial role in the semi-quantitative interpretation of gravity and magnetic potential field exploration. At present, the main inversion methods of geological body edge depth mainly include Werner deconvolution method, analytical signal amplitude method, local wave number method, Tilt-depth method, Euler deconvolution method and curvature attribute inversion method. These methods all have problems of solution selection, stability and adaptability. This paper mainly studies the adaptability of different types of data and models. Through basic principle analysis and model test, the results show that Werner deconvolution method and Euler deconvolution method are applicable to the most types of data sources, followed by curvature attribute, and Tilt-depth is the least; Werner deconvolution method, Euler deconvolution method and curvature attribute methods can adapt to many models, the Tilt-depth is least. For gravity data, the analytical signal amplitude of the first vertical derivative as the data source is applicable to all methods. For magnetic data, the analytical signal amplitude as data source is applicable to all methods. At the same time, it is suggested that other scholars should follow the following principles when using these methods to invert the edge depth of the two-dimensional body: It is recommended that Werner deconvolution is preferred, followed by curvature attribute and Euler deconvolution. The gravity data source of Werner deconvolution method and Euler deconvolution method is recommended to use the horizontal derivative of the first vertical derivative, and the magnetic data source is recommended to use the horizontal derivative. The gravity data source of curvature attribute method is recommended to use the analytical signal amplitude of the first vertical derivative, and the magnetic data source is recommended to use the analytical signal amplitude. In addition, based on the above research conclusions, some suggestions on the future research directions of the solution screening, stability and adaptability of the edge depth inversion are given.

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

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

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

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.

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

To explore in detail superficial paleochannels in Xiong'an New Area,this study investigated two profiles in the study area using the high-density resistivity method based on previous remote sensing.The interpretation results were verified through drilling.The distribution range of the paleochannels that was delineated using the high-density resistivity method was more accurate than that obtained from remote sensing.This study determined that the superficial paleochannels in the study area exhibit curved,tortuous,and braided planar distribution,achieving excellent application performance in the detailed exploration of superficial paleochannels.This study provided a new idea for future exploration and study of superficial paleochannels and can be used as a reference for the selection of methods used to investigate paleochannels in similar geological conditions.

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

This study explored the geothermal resources in Yueliangwan, Binhai County, Jiangsu Province using the controlled source audio-frequency magnetotellurics (CSAMT) method and the wide-field electromagnetic method. Through the auxiliary correction of near-field and transition-field curves, as well as the inversion based on the CSAMT data, this study obtained the electrical structure information of underground geothermal resources in the Binhai port. Meanwhile, this study acquired the information on the underground geometric structure using the microtremor exploration method. By comprehensively analyzing the interpretation results of three kinds of geophysical data, this study obtained the geothermal model of the study area and determined the locations of the anomalies. A geothermal well with a depth of 2 919 m was drilled in the study area, obtaining water yield of 2 171 m³/d with a water temperature of 51 ℃. The high consistency between the results from the comprehensive geophysical exploration and the geological and geothermal well data indicates that the comprehensive geophysical exploration method can improve the reliability of geothermal exploration results.

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

As a fast and nondestructive geophysical exploration technique,the natural source surface wave technique performs well in exploration in a complex urban environment by extracting surface waves and other information using the natural earth vibration.This study applied this technique in an urban planning area to ascertain the distribution characteristics of the strata in the area through section interpretation,the extraction of site evaluation parameters including equivalent shear wave velocity and predominant period,and 3D visualized plotting.It can be concluded that the planning area has no concealed fault and thus has excellent site conditions.The results of this study can be utilized as an important reference for the site evaluation of similar areas.

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

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.

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

Laochang, Lancang, Yunnan is one of the most important polymetallic mining areas in the southern part of Sanjiang Tethys metallogenic belt. After years of mining, the shallow resources are nearly exhausted. In recent years, granite porphyry and porphyry polymetallic mineralization have been newly discovered in the deep part of the mining area, highlighting the prospecting potential of deep polymetallic deposits. In order to trace the occurrence of deep ore-controlling strata and structures in the study area and help to make a breakthrough in deep ore prospecting, high-power induced polarization method and audio magnetotelluric method were implemented to image the deep structure situated. Results obtained from the inversion of the measured induced polarization and electromagnetic data recuperated the distribution of induced polarization anomalies and the characteristics of deep electrical structure within the study area. Combined with the available regional geological settings, the main conclusions are as follows: The low resistance and high polarization anomalies in the northwest of the survey area are deeply related to the surface ferromanganese, silver manganese, and deep polymetallic mineralization, and the high resistance and high polarization anomalies in the middle and east of the survey area are in good agreement with the deep polymetallic mineralization. The upper Carboniferous limestone and dolomite strata are thick in the west and thin in the east, with the west strata dipping to SW and the east strata overlying the Yiliu Formation of the lower Carboniferous. The concealed granite porphyry dips in NE direction, and the coupling part between its deep 2 300~2 800 m horizontal section and deep fault is a favorable area for deep polymetallic mineralization. Notably, joint interpretation yielded from the high-power induced polarization method and the audio magnetotelluric method applied improved the reliability of deep polymetallic ore detection and provided more information of positioning the subsequent drilling layout.

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

Based on the data derived from the geochemical survey of land quality in the Guyuan region, Ningxia, this study studied the background values of 30 elements (indicators) in the surface soil using mathematical statistics. This study compared the distribution and enrichment (or dilution) characteristics of elements in different parent materials (parent rocks) and land use types and further analyzed the factors restricting the distribution of the elements from the perspective of element association characteristics using the principal component analysis method. The results show that the contents of iron-philic element Ni, tungsten-philic element Mo, alkaline (earth) metal elements Na₂O, MgO, CaO, halogen elements I, F, and copper-philic element As were all higher than corresponding national background values, while the contents of the biophilic elements such as Hg, Se, organic matter, N, and Pb were lower than corresponding national background values. Parent materials (parent rocks) were the main factor controlling the characteristics of element contents in soil. In the process of soil formation, natural and man-made influences have caused the enrichment or dilution of some elements. N, Mo, I, organic matter, and S are significantly controlled by the laterite parent material and their parent rocks, and the erosion of Ca²⁺ and Na⁺ causes weathering and leaching due to hydrodynamic effects. The element contents in the soil in the river valley plain were between those of laterite and those of loess parent material. In a supergene environment, Na₂O, K₂O, and Cl, which are prone to dissolve in water, are rich in estuaries and valleys due to hydrodynamic action. P, Hg, Se, and Mo elements are locally rich due to human interference. The factor analysis shows that parent materials (parent rocks), weathering, leaching, and bioaccumulation in the process of soil formation, and human production activities all affect the background values of the surface soil in the study area. The study results will provide basic geochemical information for the assessment of the regional resources and environment.

The Dashui gold deposit in Maqu County,Gansu Province is a typical mine of the western Qinling region.Owing to continuous mining,many mined-out areas have been formed at different depths below high and steep slopes No.5 and 9,causing local surface collapse and major safety hazards.According to the requirements for environmental protection and safety,there is an urgent need to determine the spatial distribution of concealed collapse to effectively prevent geological disasters.Using the opposing coils transient electromagnetic method (OCTEM),this study conducted the fine-scale interpretation of the anomalies on the typical sections of the exploration area.Based on this,as well as the comprehensive analysis of the hydrogeological data and basic geological data of the exploration area,this study determined the transparent and three-dimensional distribution of the concealed collapse of the Dashui gold deposit.The results of this study show that the subsurface investigation of mined-out areas using the OCTEM can effectively reveal the lithologic and electrical characteristics of concealed strata in mined-out areas.Moreover,the significantly different physical properties between mined-out areas and surrounding rocks can be used to effectively identify the locations and basic morphologies of subsurface mined-out areas.The data on the boundary characteristic points of the mined-out areas on geophysical profiles with multiple exploration lines and three-dimensional modeling allow for the three-dimensional visualization of the spatial morphology of the mined-out areas.The application performance of the OCTEM,along with three-dimensional modeling,provides a technical basis for mine restoration and safety evaluation,thus effectively serving the construction of digital mines.

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

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

Denoising is an important part of magnetotelluric data processing. To enrich and develop the denoising method of magnetotelluric time series, this study introduced the LSTM network-one of the recurrent neural networks-into the square wave noise processing of the magnetotelluric time series. Different from previous studies, the measured magnetotelluric time series without human interference superimposed on simulated square wave noise were used as the input of the LSTM network, and the noise-free original time series were used as the target output of the network. After training for 1,500 epochs, the normalized cross-correlation coefficient between the time series extracted from the simulated noise signals by the network and the original time series reached 0.9718, indicating that the network has effectively learned the characteristics of the noise-free magnetotelluric time series. Finally, the denoising test results of measured square wave noise signals show that the proposed method can effectively suppress the interference of square wave noise and improve the estimation quality of impedance. This study provides a new idea for the processing of magnetotelluric time series based on deep learning.

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

The detection of landslide deposits is frequently required in the infrastructure construction of the Western China Development. However, it is difficult to distinguish the landslide deposits using conventional electromagnetic methods because of the small differences in the resistivity between the sliding surface of the sliding bed and the Quaternary overburden. Therefore, this study proposed a scheme that detected the landslide deposits using opposing-coils transient electromagnetics (OCTEM) and then traced the mountain dislocation surface reversely. Accordingly, this study established a geoelectric structure model of the landslide deposits, investigated the transient electromagnetic response patterns of landslide deposits through forward calculation, and theoretically analyzed the transient electromagnetic response patterns of landslide deposits with different thicknesses and those of landslide deposits under different thicknesses of the Quaternary overburden. As verified by the detection results of known landslides, the method proposed in this study is correct and that OCTEM is valid in detecting landslide deposits in mountainous areas.

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

To achieve the goals of peak carbon dioxide emissions and carbon neutrality, geothermal energy has great prospects for utilization as a type of widely distributed green and clean energy. The tectonic fissure-hosted geothermal water is regarded as an important type of hydrothermal energy for development and utilization because of its high water yield and easy reinjection. This study systematically analyzed the regional structures, formation lithology, water storage space, and water yield property of the urban area of Meixian County in the west of Guanzhong Plain through the regional integrated geophysical exploration, aiming to guide the target area prediction and well placement of geothermal wells. The results show that three concealed faults are present in the target area, of which two faults with favorable water yield property and large scale can be regarded as the faults of the target area. Based on this, geothermal wells were arranged near the fault prediction lines on the hanging wall of the faults, and the weathered zones of the bedrock surfaces were penetrated vertically along the dip angles of the faults. Given the actual geological conditions, such as the faults and the burial depth of the bedrock surface, the geothermal wells had an average drilling depth of 500 m from the bedrock surface. The drilling results show that there are dual-structure thermal reservoirs in the target area, including thermal reservoirs of pore water in the Neogene clastics and those of the bedrock fissure water. Among the eight geothermal wells, seven wells have a water yield of more than 100 m?/h, which mainly originates from the bedrock fissure water, and only one well has a relatively low water yield, which is mainly sourced from the pore water in the Neogene clastics.

Vanadium (V) is an essential trace element required by organisms for maintaining their normal life activities. It is also a harmful element listed as a priority environmental pollutant by the United Nations Environment Programme (UNEP). The study of the migration and enrichment patterns of V in the soil and plant system is of great practical significance for further understanding the ecological geochemical behavior of V and ensuring the safety of agricultural products and human health. This study systematically sampled the soil and plants in some ordinary farmland in Linyi City, Shandong Province and analyzed and tested the contents of V and its associated elements in the soil and plant samples. Moreover, this study conducted the source analysis and pollution assessment of V and investigated the migration and transformation patterns of V in the soil-plant system using statistical methods such as descriptive statistics, correlation analysis, and cluster analysis, as well as the single factor pollution index method, the potential ecological risk index method, and the biological enrichment coefficient method. The results are as follows: V is relatively concentrated in the study area, and its content increases with an increase in the Fe and Ti contents and decreases with an increase in the SiO₂, Na₂O, Sr, and CaO contents; The V in the study area mainly originates from the weathering of parent rocks, and the parts with a high V content is related to magnetite; As shown by the results of the single factor index method and the potential ecological risk index method, V is relatively clean in the soils of the study area, but attention should be paid to the pollution of the associated Cd; V is enriched primarily in the roots of plants, and plants' absorption capacity of V is generally negatively correlated with the contents of Cu, Pb, Zn, Ni, Co, Cd, and especially Cr in soils and is positively correlated with the As content in soils. This study enriches the ecological geochemical theory of V and provides a scientific basis for regional agricultural production, environmental quality assessment, and ecological pollution control.

Deep seismic reflection is one of the most effective means of studying the deep geological structure of the Earth.However,the energy of seismic waves exponentially decreases due to the filtering by the Earth,resulting in weak energy of effective deep seismic reflection signals.In this case,deep seismic reflection data are liable to be seriously disturbed by background noise,and thus it is difficult to obtain accurate images of deep geological structures.According to the study on the differences in the distribution of effective signals and random noise of deep seismic reflection data on different scales in the Shearlet domain,seismic signals on different scales are affected by random noise to different extents.Furthermore,with the signal-to-noise ratio,the L2 norm of Shearlet coefficients,and the residual errors of random noise in deep seismic reflection data as the parameters for threshold estimation,this study developed a random noise suppression method that is adaptive to different scales to minimize the effects of random noise.Theoretical model data and actual tests of deep seismic reflection data verified that this method can effectively eliminate the disturbance of random noise,improve the overall signal-to-noise ratio of seismic sections,and realize the accurate imaging of weak deep seismic reflection signals.

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

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