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 the light of typical coneshaped columns in the Lu'an mine of Shanxi Province, the authors

established a mathematical model for the collapse column, and used the wave equation model for

seismic ray tracing and wavefield simulation of collapse columns. The simulation results show that,

due to the special nature of the collapse columns, such waves as the normal reflected wave, the fault

point diffraction wave, the delay diffraction wave, the delay reflected wave and  the "diffraction

wave" consisting of Pwave field are formed around the collapse columns. On such a basis, the field

shot was simulated, and then a single shot record for routine processing  was generated to produce

stacking sections and migrated sections. The forward section and the actual data analysis reveal that

the fallen columns of the special wave constitute an important feature for recognizing collapse

columns; nevertheless, the resultant scale of the actual seismic data interpretation is often smaller

than the scale of actual collapse column. Some suggestions are also put forward for reference.

Low density geochemical survey in Yishenjilike mountain area led to the discovery of a huge gold geochemical block, and the verification and evaluation of gold anomalies led to the discovery of the Bogutu gold deposit. In combination with the geological characteristics of the prospecting area, the authors carried out a series of geological-geophysical-geochemical exploration work, delineated quite a few geochemical and IP anomalies, and detected the characteristics of ore-bearing structural belt. Through trenching and drilling verification, the authors found more than 40 gold orebodies, thus achieving good ore-prospecting results.

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.

This paper has summed up the progress of the ERI method over the past decade of years as well as its future development trend in the following aspects: ① A comparison of the performances of the main ERI instruments used at present shows that the ERI instruments tend to develop in the multi-channel, multi-parameter, multi-functional, high-power direction; ② ERI measurement environment has changed from surface measurement to water surface, underwater and cross-hole measurements, with the last three kinds of measurements analyzed in this paper; ③ On the basis of analyzing ERI data processing method and inverse development status, this paper describes three-dimensional and four-dimensional inversion theory of ERI with practical examples; ④ ERT applications are summed up, and several new applications are introduced. It is concluded that, with the improvement of the probing depth and observation precision as well as the diversification of the observation models, the application field of ERI will become broader and broader, and this technique will surely have wide development prospect.

A review on the airborne gravity survey and airborne magnetic survey are given in this paper. The

authors hold that these techniques have entered into a new development period, as evidenced by the

emergence of such technologic indicators as airborne vector magnetometry, magnetic fulltensor LTSSQUID

and HTSSQUID gradiometry, airborne gravimetry, gravity gradiometry and geophysical survey by UAV.

This paper gives a brief review of the history of the airborne gravimetry. Based on the principle of the airborne gravimetry, the paper deals emphatically with the history, the present  research situation and the developments of the airborne scalar gravity survey system. Further development trends are also indicated.

The R-mode cluster analysis is a mathematic statistical method for obtaining the quantitative similarity of several elements. Its procedure includes: the conversion of the original data; the solution of the relevant coefficient ; the clustering of the result. The above operation can be realized by using the data analysis tool of Excel. This method is quite suitable for field utilization.

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

 With powerful Matlab image processing functions, this paper has realized the 3D display of ground penetrating radar data, whose procedures are simple to prepare and easy to learn. A detailed description of the code is given, and the three-dimensional test data show that, by setting transparency, the target can be displayed in an intuitive and visual way.

Porphyry copper deposit is the most important copper deposit type in China. With the deepening of mineral exploitation, exploration geochemistry in mineral exploration has become increasingly important. Based on related literature, this paper sums up the exploration geochemical research results of porphyry copper deposits, which include such aspects as geochemical characteristics, exploration methods, anomaly evaluation and prospecting indicators. Exemplified by the Fujiawu copper deposit, this paper reports the latest advances in the study of porphyry copper deposits.

Element abundances of the continental crust and rocks cited in the past and recent literature have been based on compilations of data from various studies. This leads to uncertainties in sample representativeness and data quality. The present study is based on systematic collection of 28 253 individual rock samples over an area of 3.3 million km² in eastern China, east of eastern longitude of 105°.The sampling involves more than 800 igneous intrusive bodies and metamorphic complexes as well as more than 500 type stratigraphic sections. From the individual rock samples, 2 718 composite samples were made and analyzed for 77 elements by 15 specific methods, dominantly XRF and INAA. Analytical quality was controlled by international and national preliminary geochemical reference materials of GSR, GAu and GPt series. Synthetic results from geological, geochemical and geophysical studies were used to construct crustal constitution model, from which element abundances of the continental crust in the North China platform, the upper crust and exposed crust in eastern China, chemical composition of igneous rock in China and of sedimentary rock and metamorphic rock in eastern China were derived.

This paper has described and reviewed the pinciples,expermental set up and observational results of applying atom interferometer to measuring the earth's gravitational acceleration.This method was developed by Nobelist Steven Chu,M.Kaservich,A.Peters et al.,who demonstrated a resolution of 10^-10.The application of this technique to geophysics and the related problems are also discussed.

In drawing the contour map of geophysical data, suitable gridding methods should be chosen according to objective

environment characteristics and characteristics of data themselves. With practical examples, this paper deals with some common

gridding methods such as inverse distance to a power, Kriging, Minimum Curvatrue, Nearest Neighbor, Polynomial Regression, Radial

Basis Function, and Triangulation/Liner Interpolation, probing into their choosing means, applicable fields and parameter

installment.

This paper puts forward a new method for calculating anomaly area—the polygonous approximation method,and gives corresponding algorithm and precision controlling technique.With this method,one can calculate anomaly area rapidly and precisely,thus yielding relatively satisfactory results.

Based on two-dimensional Fourier transform and half-wave theory, this paper has studied the seismic Rayleigh wave dispersion curve extraction in f-k domain and made this theory fit in with a program by means of Delphi7.0. It is concluded that the f-k method overcomes the shortcomings of the one-dimensional digital processing technology and makes full use of multi-channel Rayleigh wave data record.

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

IP is an important method for mineral resources exploration, but it can only be applied in a few pivotal places because its difficult performance, and hence the information obtained from the survey area is very limited. The aim of this study is to find a simple and effective IP method with which we can get much valuable information form the survey area so as to improve the exploration effect. In the Yinan gold ore district, the authors applied the gradient sounding profile method, calculated 2D resistivity and obtained the IP model. The results show that the gradient sounding profile method is simple and effective.

As an important prospecting technique and an effective means for obtaining mineralization data,

geochemical exploration has been proved to be very successful in mineral exploration. This paper focuses on

commenting the present research situation and application effect of some new methods such as structural

superimposed halos method, heat released mercury method, separatory electrogeochemistry method, enzyme leach, and

geogas and selective leaching of mobile metals method. It is emphasized that any one of these methods has its

unique applicability and that, in the practical application, we should pay attention to the cooperation of

geochemical exploration, geologicalgeophysical exploration and remote sensing and depend on the study of

geological background so as to demonstrate the usefulness and effectiveness of geochemical exploration.

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

The implied contour level and color scheme in Surfer software fail to express the subtle difference of DEM and the effect

of color solid. In addition, the artificial setting of the levels and color values are timeconsuming and laborious, and the

results are sometimes not perfect. With the consideration of contour level and color scheme and on the basis of Surfer platform

automation technology, this paper presents a program that can automatically generate a level file with different intervals and

different colors, thus resulting in satisfactory effect and efficiency.

The present paper makes a brief description of the progress of several main electric methods which havebeen developed quite rspidly since 1980's.They include induced polarization method,frequency spectrum IPmethod,trandient electromagnetic method, controlled-source audio-frequency magnetotelluric method and GPR.

According to aeromagnetic and gravitational data, the boundary and range of Ordos basin were determined based on an analysis of the characteristics of gravity and magnetic fields. And on the basis of compiling depth map of the metamorphic basement and structuring zoning map, research was conducted on the basin’s basement structure, characteristics and features of depth change, structure framework, and caprock thickness. The research indicates that the metamorphic basement is composed of Proterozoic metamorphic series, and the buried depth of crystalline basement can reach 5 000 to 20 000 meters. The caprock is the layers of Ediacaran, Paleozoic, and Mesozoic. The occurrence and development of the basin are restricted by nearly NE-and NWW-trending structures, forming a pattern of four depressions and three uplifts. All the new understanding and conclusions provide a reference for further oil and gas exploration in the basin.

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

This paper proposes an equivalent second order elastic wave equation to solve the problem of being unable to completely

separate the coupled P and S wave by full elastic wave equation. Through solving this equivalent wave equation by high-order

staggeredgrid finite difference scheme together with Flux Correction Technology (FCT) and separating wave fields of the

isotropic model and layered model, the authors accurately obtained the hybrid wave field and completely separated fields of pure

P wave and pure S wave fields. An analysis of the numerical results shows that the method is effective and reliable in isotropic

media, and there exists abundant energy transform information in separated pure P and pure S wave field. The result of the study

is of significance in understanding the propagating law and the elastic wave theory in the complex wave field.

With the extensive adoption of computer technology in geology and geophysics, computer graphics becomes more and more important. For the purpose of improving quality and efficiency, several software should be combined in practical work. In this paper, some basic characteristics of Surfer and MapGIS are discussed, and their application in geological field is described from the angle of geological mapping, thus drawing forth the necessity of the conversion between Surfer and MapGIS. The general method and steps for the conversion of maps between Surfer and MapGIS are presented in detail, and several problems concerning the conversion and corresponding solutions are emphatically discussed.

The high-resolution position data in the centimeter grade are extracted from the binary output records of the hand-held GPS position indicator, and the multiple average measurement and post-operation position difference correction method are used so as to decrease the planar locating error of the portable and cheap hand-held GPS position indicator from several meters to 1 m or so. Thus the precision of the sub-meter grade can be attained.

On the basis of accurate analysis of 154 composite soil samples collected from various landscape in China and other reference information, abundance of 79 elements and composition of soils in China have been given, chemical composition of soils under the influence of matrix rock and supergenesis geochemistry condition have been studied preliminarily.

 Vibroseis exploration, as an important method of seismic exploration, has become increasingly valued by geologists. During the field work, different geological conditions need different parameters, and the choice of suitable excitation parameters has become a very important problem. This paper mainly introduces six kinds of parameters, namely numbers of controlled seismic source, scanning bandwidth, vibration period, scanning length, scanning slopes, and vibration rate. The influence of these parameters on the quality of seismic records was studied in detail, and the simulation of the proper parameters was performed in Jiulishan area to enhance the resolution of vibroseis exploration and improve the signaltonoise ratio of seismic records.

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

This paper has put forward the idea of utilizing Surfer to draw the initial data profile-plan. The programme compiled can realize the construction of Bln file. The profile-plans for regular net and irregular net have been constructed, and the results are satisfactory.

The development of the gravity gradiometer is described simply in this paper, and the measuring principle and development experience of the rotating accelerometer gravity gradiometer are emphatically discussed. On the basis of researches on the existing airborne gravity gradiometer, the prospects of the airborne gravity gradiometer are also presented.

 Numerical integration of Hankel transforms is effective tools for EM Sounding 's forward numerical simulation, this paper made out formula derivation of numerical integration of Hankel transforms by digital filtering, and use digital coefficients to do numerical compute which was put forward by Guptasama and Singh，finally contrasted to theoretical resolve expression and analyzed this algorithm's error distribution. The results show that the calculation of this algorithm continuously approximate its theoretical solution, it has no oscillation, high precision and great practical value in the numerical simulation study.

Usually, city road consists of the surface layer and the subbase layer, and each layer contains several layers of different media with different relative dielectric constants. So using one relative dielectric constant to analyze the GPR data of all depths in city road detection is not accurate. This paper deduced the calculation formula of the equivalent dielectric constant of multi-layer underground media. Then the authors took two-layer media model and three-layer media model as examples to calculate the equivalent dielectric constant and the relation between the depth and the travel time. At last, theoretical modeling data of two-layer media were used to check the formula, and the results prove that the calculation formula of equivalent dielectric constant of multi-layer underground media is much better for practical GPR data analysis when there are multi-layer underground media.

Migration velocity analysis and migration imaging constitute two important parts in seismic data processing. At

present, time migration has become mature, and depth migration is getting more and more perfect. The common method for time

domain migration imaging is pre-stack time migration. By adopting stacking velocity analysis along the layer, exact layer

stacking velocity can be obtained. Through dip correction, pre-stack time migration and CRP de-migration velocity analysis, the

velocity is optimized step by step, and then a desired RMS velocity field that is up to the geological rule is acquired. In

addition, the method for building the accurate migration velocity field is summed up through the study of the depth migration

method. A new seismic data processing flow in combination of Kirchhoff arithmetic based on ray tracing and wave equation

arithmetic based on wave field extrapolation is presented. As a result, migration velocity analysis and migration imaging are

considerably improved.

According to the data obtained from air-borne electromagnetic and magnetic survey and

ground two-frequency IP and magnetic survey, this paper discusses the relationship between the

features of air-borne and ground geophysical composite anomalies and the ore resource distribution.

On the basis of an integrated analysis, geophysical composite anomaly criteria in search for iron, zinc

and lead deposits were established, and 12 important ore-prospecting targets were delineated, which

provides very important clues for finding iron, zinc, lead and some other ore resources.

In this paper,a historical review of the gravity gradiometry is given, the application of this technique to oil exploration and some other fields is described,and its development in future is predicted.

On the basis of mote than230 English and Russian papers or monographsissued in the last 30 years as well as nearly 50 Chinese articles published overthe past 10 years on the inversed problem in g avity and magnetic explora-tion, combined with his practice in the study of the inversed problem, the all-thor expounds the inversed methods in gravity and magnetic exploration cur-rently used both at home and abroad, briefs the readers about the researchsituation in China and foreign countries, and makes a detailed review on achi-evements gained in China in comparison with the research levels abroad.Final-ly, suggestions are put forward concerning some subjects which are worthnoticing in future research work.

In this paper, the working principle of three satellites (CHAMP, GRACE and GOCE) has been described, and the important geopotential models and the newest geopotential models (EIGEN-CG01C, GGM02) have been introduced.

Recommendation system algorithms, having recently garnered significant attention in the field of digital Earth science, are expected to be widely applied in metallogenic prediction. Traditional metallogenic prediction studies fail to fully mine the various types of semantic information in massive geoscience data. The deep interest evolution network (DIEN), as a recommendation system algorithm, can fully mine semantic information to predict user preferences. Therefore, this study employed the DIEN model as the prediction model and the semantic information extracted from bedrock interpretation as the ore-controlling elements according to the database provided by the Western Australian government. The model was trained to perform metallogenic prediction for the study area. The prediction results indicate that 92.95% of uranium ore occurrences fell within the medium-high probability zone in the prediction map, with some unknown zones also showing high prediction probabilities. After removing known uranium ore occurrences in some zones, the retrained model still yielded medium-high prediction probabilities in these zones. The results suggest that the DIEN can effectively mine semantic information in metallogenic prediction studies, and the DIEN model exhibits strong predictive capacity for the study area, providing a novel approach for metallogenic prediction studies.

Soil carbon pools play a significant role in regulating global carbon balance and mitigating greenhouse gases. Hence, estimating soil carbon stocks is critical for assessing the carbon cycle in terrestrial ecosystems. Based on the soil carbon data obtained from the land quality geochemical survey in the study area, this study estimated the stocks of total, organic, and inorganic carbon of various soil layers in Northwest China using the unit soil carbon amount (USCA) method. It analyzed the content characteristics of organic and inorganic carbon in soil under different soil, land use, and topographic types. The results of this study are as follows: (1) All the soil layers at depths ranging from 0 to 2 m in the study area exhibited total carbon of 10 099.4 Mt, including 1 224.8 Mt in the topsoil layer (0~0.2 m), 5 345.9 Mt in the upper soil layer (0~1.0 m), and 4 753.5 Mt in the lower soil layer (1.0~2.0 m). Inorganic carbon predominated in all the soil layers, with its proportion gradually increasing from top to bottom, whereas organic carbon was principally concentrated in the topsoil layer; (2) The high-value areas of inorganic carbon content were primarily distributed in the Huangshui Valley of Qinghai Province, and the Loess Plateau region covering the Longzhong area of Gansu Province, northern Shaanxi Province, and southern Ningxia Province. In contrast, the high-value areas of organic carbon content were chiefly distributed in the Qilian Mountains; (3) The aeolian sandy soil exhibited the lowest organic, inorganic, and total carbon contents in the topsoil and deep soil layers. The dark loessial soil and the loessal soil showed the highest inorganic carbon content in the topsoil layer. The dark felty soil and the dark loessial soil displayed the highest organic carbon contents in the topsoil and deep soil layers, respectively. Additionally, the dark felty soil had the highest total carbon content in the topsoil and deep soil layers; (4) Forests exhibited the highest organic carbon content in the topsoil and deep soil layers, and the highest total carbon content in the topsoil layer. Grasslands showed the highest inorganic and total carbon contents in the topsoil layer. Cultivated land had the highest inorganic carbon content in the deep soil layer. Bare land manifested the lowest inorganic, organic, and total carbon contents; (5) Mountains displayed the highest organic and total carbon contents in the topsoil and deep soil layers. Loess had the highest inorganic carbon content in the topsoil and deep soil layers. Plains showed intermediate carbon contents generally between those of loess and mountains. Besides, high-altitude areas manifested extremely high organic carbon content.

The Mianning-Dechang area in western Sichuan serves as the most important metallogenic belt of light rare earth elements (LREEs) in China. To make breakthroughs in the exploration of rare earth resources in the Dechang area, a 1:50 000 stream sediment survey was conducted in this study. The analysis of test data characteristics and the extraction of geochemical anomalies reveal that the total rare-earth oxides (REOs) in the area exhibit a pronounced enrichment pattern and that element anomalies largely overlap the spatial distribution of related geological bodies. Through comprehensive analysis using the cumulative frequency method and iterative method, this study determined the lower limits of anomalies and, accordingly, plotted element anomaly maps, with five main anomaly areas being delineated. The comprehensive evaluation of anomalies revealed four prospecting target areas: Huangjiaba, Jiaobacun, Yibasan, and Huajiaoyuan. The analysis of metallogenic geological conditions and the anomaly verification based on drilling in the Gannan area led to the discovery of three light rare earth deposits in the Huangjiaba prospecting target area, two heavy rare earth deposits in the Jiaobacun prospecting target area, two heavy rare earth deposits in the Yibasan prospecting target area, and two heavy rare earth deposits in the Huajiaoyuan prospecting target area. This study posits that the Triassic biotite moyite and biotite monzogranite in the study area are the metallogenic parent rocks of ion adsorption-type rare earth resources, with REEs primarily undergoing enrichment and mineralization in completely weathered layers. Therefore, a simple and effective prospecting pattern for "endogenous and exogenous" ion adsorption-type rare earth deposits in the Dechang area consists of analyzing the geochemical characteristics of the total REOs based on a 1:50 000 stream sediment survey, delineating metallogenic prospect areas that indicate parent rocks for REE enrichment, and selecting sections favorable for the formation and preservation of weathered crusts based on the hypergenic conditions of the enrichment areas, thus achieving the quick delineation of the prospecting target areas.

Over the past century, electromagnetic exploration technology has evolved from direct current resistivity and induced polarization methods to a comprehensive geophysical system. Yet, in China's new mineral exploration phase, challenges like deep-mining needs, cultural noise, and weak 3D interpretation limit traditional methods. High-power-ultrahigh-power electromagnetic technology, by boosting transmission current, combats these issues. It enhances detection depth, enables 3D exploration, and drives technological and application innovation. This paper reviews the development of high-power-ultrahigh-power electromagnetic instruments and current research. It emphasizes that technologies like true 3D full-waveform IP collection and inversion, tensor CSAMT collection and inversion, and multi-parameter joint inversion of time-and frequency-domain EM methods can strengthen deep-target detection. Future research should tackle anisotropic 3D inversion, full-domain inversion with a field source, and extracting polarization and magnetization rates under complex constraints. These advances will propel electromagnetic methods toward greater depth, precision, and intelligence, supporting China's renewed mineral exploration efforts.

Many cities or urban residential areas in central and western China reside in alluvial plains formed from piedmont alluvial fans. Hence, revealing the stratigraphic architectures and stability of alluvial fans holds critical significance for urban construction planning and rational land use. The alluvial fan in the eastern piedmont of the Liupan Mountains hosts the urban residential areas and villages of Guyuan City, with a dense population. Moreover, the alluvial fan develops several event deposits recording the activity of the alluvial fan under tectonic movements and climatic changes. Through field geological survey, optically stimulated luminescence dating, controlled source audio-frequency magnetotellurics (CSAMT), and conventional radon measurement, this study revealed the stratigraphic architecture of the alluvial fan and its two-phase event deposits (~43.33 ka B.P. and 22.92~20.72 ka B.P) since the Late Pleistocene. As indicated by the CSAMT and conventional radon measurement results, the alluvial fan still exhibits high activity under the influence of the Haiyuan and Qingshuihe faults. The results of this study provide fundamental data for crustal stability assessment, prevention and control of geologic hazards, and engineering construction in the Liupanshan area.

With the application of high-precision,high-density 3D seismic technology and significant improvements in acquisition efficiency,the volume of data from nodal seismic data acquisition has expanded sharply.This leads to growing demands for the quality monitoring of nodal seismic acquisition.Especially,the lag in the synthesis of common shot gather data in node data has affected the quality monitoring and processing efficiency of seismic data.Therefore,the demand for quality control technology has become increasingly prominent in nodal seismic data acquisition.By delving into technologies including the visual monitoring of pre-acquisition node states,node data synthesis,and seismic data quality monitoring,this study independently developed a quality monitoring platform for nodal seismic data acquisition,enabling quality control for the whole nodal seismic data acquisition,involving equipment status,data synthesis,and data quality control.This platform has achieved satisfactory application results in a practical seismic data acquisition project.

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

In practical detection operations using ground-penetrating radar (GPR), factors such as environmental noise and instrument errors frequently cause signals to be mixed with substantial noise, seriously reducing signal quality and the reliability of analytical results. To address this issue, this study proposed a time-frequency peak filtering method combined with minimum mean cross-entropy (TFPF-MMCE) for denoising GPR signals. This method combined time-frequency peak filtering with the cross-entropy function, enabling effective noise suppression and precise preservation of valid signals through precise optimization of the time-frequency representation, thereby significantly improving the quality of GPR signals. Numerical simulation and field GPR experiments validated that the TFPF-MMCE method exhibited a high noise removal capability and, thus, can effectively eliminate random noise while significantly improving signal clarity and reliability. Compared to traditional denoising methods, TFPF-MMCE shows significant advantages in denoising effectiveness and noise resistance stability, suggesting promising application potential and practical value in the field of GPR signal processing.

To evaluate the resource potential of the Jinchanshan mining area, this study conducted analysis and tests of metal element content in soil samples from two geochemical profiles using the electro-adsorption method. By combining the geological conditions of the mining area, this study revealed pronounced positive geochemical anomalies of Au, Ag, Cu, Pb, and Zn above the known gold deposits. The anomalous areas corresponded well with deposits, confirming the effectiveness and feasibility of the electro-adsorption method in the study area. The study identified geochemical anomalies Ⅰ and Ⅱ to the west of the Guaibanggou-Yangpo-Xiaoxigou mineralization zone in the first geochemical profile. Along the second profile, located between the Guaibanggou-Yangpo-Xiaoxigou and Nandawa-Limazigou-Loufengmao mineralization zones, anomalies Ⅲ and Ⅳ were observed at the westernmost end. The comprehensive geological analysis of the mining area indicates that the Ⅰ and Ⅲ anomaly zones exhibit favorable geological conditions for mineralization, serving as play fairways. The play fairway prediction conducted in this study provides targets for future exploration in the mining area.

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

In thereconstruction of actual subsurface structures, strong noise limits the accuracy of the magnetotelluric (MT) method,causing adverse effects on later data interpretation. Given this and the characteristics of the MT time series,this study analyzed different types of noise in the MT time series,proposing a signal denoising technique based on variational mode decomposition (VMD) and long short-term memory (LSTM) predictive reconstruction. First, baseline drift correctionwas performed for the original MT datausing the VMD signal decomposition algorithm. Then, the time series was further decomposed into multiple different intrinsic mode functions (IMFs) through VMD. The LSTM time series detection model was trained using interference-free data in the RSE component, which was then identified. Afterward, the time intervals containing noise weremarked, the increasement of noise was calculated, and the noise information wastransmitted to the original signal for truncation and removal. Finally, an LSTM multi-dimensional prediction model was trained for the IMFs, followed by the prediction of missing values under various modes. The predicted results under all modes were combined to obtain the final predicted MT signals. After signal reconstruction, a secondary signal-noise separationwas performed for spike-pulse noise that was not effectively identified through VMD. TheVMD-LSTM-based signal denoisingtechnique can accurately identify strong noise in MT signals by merely processing the time series intervals containing noise, thuseffectively preserving interference-free data. Moreover, its prediction errors can berestricted within the allowable error range of the data processing for MT signals. Therefore, this technique enjoys significant denoising effects.

This study investigated the Panxi area as an example to delineate faults and determine their current activity levels using aeromagnetic data and precise relocation results of small earthquakes. A total of 42 faults were delineated in the study area. Among them, 21 faults were inferred to be active currently, including 10 newly inferred active faults. This study examined the three-dimensional structural characteristics of some local sections of major faults in the study area. The results indicate that precise relocation results of small earthquakes can identify highly active faults and characterize their deep structures. Additionally, based on the delineation of basement faults using aeromagnetic data, the locations of active faults were constrained, and concealed active faults within the sedimentary cover were also determined. The proposed method holds certain practical significance for promoting research on the spatial distribution and activity of fault structures using aeromagnetic data.

The Triassic strata in the Lunnan area of the Tarim Basin represent a continental deltaic sedimentary system,with sedimentary subfacies including deltaic plain,deltaic front,and prodelta.The rapid phase transition of reservoirs and the high-frequency sand-mudstone alternating deposition create thin,highly heterogeneous reservoirs,rendering high-precision reservoir prediction extremely challenging.Under the guidance of sedimentary petrology and seismic sequence stratigraphy,this study conducted comprehensive seismic and geological research.Then,based on isochronous sequence interpretation,as well as seismic facies analytical results,this study established a lithofacies model.By constraining the pre-stack geostatistical inversion process,this study determined the spatial distribution of sand bodies.The practical application demonstrates that the proposed method enhances the vertical resolution of heterogeneous,thin reservoirs while significantly reducing lateral uncertainty.The predicted results align with actual drilling and production performance data and thus can provide valuable support for the efficient exploitation of hydrocarbon reservoirs.

Due to dense buildings and structures and insufficient drilling surveys, the construction of shield tunnels passing through urban karst formations that host dense buildings faces significant risks of surface fracturing and subsidence caused by karst development. Hence, this study employed the microtremor survey technology with strong anti-interference capability in complex environments to address this challenge. Based on the technology, it analyzed the structural characteristics of wave velocities in underground rock formations through the inversion of the apparent shear-wave velocity profile. Combined with geological drilling data, it inferred the bedrock interface, highly weathered unconsolidated formations, and karst cave anomaly zones. Key findings are as follows: (1) The apparent shear-wave velocities in the study area gradually increased from the shallow to deep formations. Formations with wave velocities above and below 300 m/s were inferred to be limestone and Quaternary formations, respectively, with the rock-soil interface at depths approximately between 10~15 m; (2) Seven low-value anomaly zones of apparent shear-wave velocities ranging from 150~240 m/s were interpreted. They were presumed to be unconsolidated formations or karst caves at depths ranging from 8~30 m. Relying on strong anti-interference and high accuracy, the microtremor survey technology can accurately identify the shear-wave velocity structures of underground profiles, lithologic interfaces of formations, unconsolidated formations, and karst cave anomalies. Therefore, the technology is effective in the geological exploration of urban dense building areas with karst development.

This study investigated data from a 1:50,000 stream sediment survey in the Juxian-Wulian area, Shandong Province using factor analysis. By extracting eight representative factors, this study identified element assemblage types. Then, this study performed geochemical zoning based on the factor scores and discussed the relationships between various sub-zones and their geological background. Based on the geochemical zoning results, as well as geological conditions for mineralization, this study determined favorable geological bodies and prospecting targets and discovered new prospecting clues.The most significant mineralization combination in this area is Au-Cu-Ag-Mo-Bi, followed by Pb-Zn; The V-Ti-Co-Mn combination and Ni-Cr combination can serve as exploration elements, indicating that there may be favorable mineralization mechanisms in the center and deep parts of the combination anomaly zone. Finding volcanic craters and hidden explosive breccia tubes in the distribution areas of volcanic rocks in this region or area is an important direction for mineral exploration; In the area of Shichang Fangzi Village in the eastern part of the research area, there is a comprehensive zoning with a F₂-F₄-F₁ three factor combination model. The Mesozoic Buliu sequence and Weideshan sequence rock bodies are favorable geological bodies for mineralization, and the NE trending structural belt is a favorable place for mineralization, indicating the direction of prospecting.

The deep mining of geological mineral information from geochemical exploration data has been a hot research topic in mathematical geology and geological big data. Despite China's abundant regional geochemical exploration data, the deep mining of geological mineral information from these data remains limited, necessitating a scientific, efficient, simple, and feasible data processing workflow and analytical methodology. This study investigated the Gaoqiao area in Huixian County, Gansu Province, China. According to the geological background and the theories of element properties and geochemical behavior, this study processed relevant element data to mine the geological mineral information in geochemical exploration data. It established preliminary mathematical models for the boundary delineation and lithofacies classification of intermediate-acid rock masses, and the boundary delineation of mafic volcanic rocks in the Gaoqiao area to scientifically guide geological mapping. It preliminarily established the target delineation model for tectonic altered rock-hosted gold deposits. The model's effectiveness was substantiated by seven newly delineated target areas with promising prospecting potential. The mineral inspection identified five ore occurrences, including four reported for anomalies related to mineralization, with two currently under provincial geological exploration. The results of this study show that by calculating and processing data based on the geochemical properties of elements, the hidden information in regional geochemical exploration data can be further mined to effectively guide and modify geological mapping, thereby enhancing mapping efficiency and quality. High-quality anomaly information can be further extracted from geochemical exploration data to effectively guide mineral prospecting in new areas.

Seismic data processing reveals that internal multiples exhibit highly complex formation mechanisms,making their accurate identification and effective suppression a persistent challenge in geophysical exploration.Traditional methods for internal multiple suppression frequently require manual identification of subsurface reflection interfaces,making them difficult to apply to complex underground medium structures.Moreover,these methods are not only computationally cumbersome but also typically ensure only temporal and positional consistency when predicting internal multiples.The amplitude often deviates from observed values,requiring adaptive matching subtraction algorithms for effective suppression.This study developed an internal multiple suppression method based on Marchenko theory.Specifically,the wavefield relationships between the focusing function and Green’s function were constructed using the convolution and correlation reciprocity theorem of the Green’s function during data processing.The Green’s function was then solved using the focusing function,yielding either multiples or primaries constructed from the Green’s function.This method requires only the background velocity or the original data as operators during the iterative multidimensional correlation and convolution process,rendering it simple and computationally efficient. This study constructed an expression for the primary wave field using the Green’s function and the Marchenko equation.The tests using the SMAART model and actual data from the Gulf of Mexico demonstrate that the Marchenko method can effectively suppress internal multiples under the conditions of complex subsurface media.The iterative process requires no velocity information,providing significant advantages over conventional methods and great potential for application in complex underground environments where layers are difficult to distinguish.

The exploration and exploitation practices in the Sichuan Basin in recent years indicate that breakthroughs have been achieved in the Jurassic continental tight sandstones.Nevertheless,due to the low porosity and permeability of tight sandstone,conventional post-stack inversion frequently exhibits limited resolution,failing to meet the accuracy requirements for the prediction of actual exploration reservoirs.This necessitates pre-stack inversion for detailed characterization of tight sandstones,while S-wave velocity is crucial to pre-stack inversion.Based on continental exploration wells drilled in the southeastern Sichuan Basin in recent years,this study developed a petrophysical modeling technique for dense sandstones in this region.Specifically,given the low permeability of tight sandstones and the uneven mixing of fluids in the pore space,the Domenico model was preferentially employed to calculate the pore fluid modulus.Although fluid modulus and density are inevitably variable under the actual subsurface conditions,previous studies typically use constant values to conduct petrophysical modeling for tight sandstones.In this study,depth-dependent values were applied.Tight sandstones in the southeastern Sichuan Basin generally exhibit a porosity of less than 10%.Therefore,calculations using the Nur and the Krief models will yield high errors.Given this,this study preferred using the Lee-Pride model to calculate the skeleton modulus and controlled the relationship between the rock matrix and the skeleton by introducing the value of the cementation parameter.The application of the established petrophysical model of tight sandstone to an actual survey area indicates high agreement with data from actual wells.Additionally,based on log statistics,Poisson's ratio,the most sensitive parameter is used for high-precision pre-stack inversion in the proposed technique,enabling detailed characterization and prediction of the internal structure of channel sandstones.

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

Conventional splicing methods aim to serve structural interpretation and align the reflection energy and frequency of large strata based on seismic data themselves.They adopt seismic data only from one study area in processing data of overlap zones,failing to fully utilize the effective information in seismic data of all study areas.Consequently,the resulting low-fidelity seismic data in overlap zones severely affect subsequent discrimination of reservoir connectivity and hydrocarbon-bearing properties.This study proposed a weighted fusion-based data spicing method for overlap zones,where seismic data from different study areas are fused with corresponding weights to generate a trace of seismic data.The application of the proposed method to actual seismic data shows that the processing results based on the fusion and splicing of data in overlap zones can effectively improve the quality of seismic data,with high continuity of seismic events on the profile, contributing significantly to the discrimination of the connectivity of shallow sand bodies.

Understanding the distribution patterns of selenium in soils and crops is critical to developing selenium-rich industries. Enshi City in Hubei Province is known for its extensive selenium-rich soils, establishing this city as a promising area for selenium-rich agriculture. This study investigated Xintang Township in Enshi. Based on the organization and analysis of the geochemical data of 2 469 soil samples and 237 crop samples of maize, potatoes, rice, radish, cabbage, and tea, this study offered a systematic summary of the selenium distribution in soils and factors influencing selenium content in crops in the study area. The results indicate that the topsoils exhibit selenium content ranging from 0.14×10^-6 to 25.74×10^-6, with a background value of 0.81×10^-6, which is 3.7 times the national background of selenium content in soils. Selenium-rich soils cover 86.23% of the total area of the study area, and two NEE-directed selenium-rich belts are found. The spatial distribution of selenium in soils is closely related to soil-forming parent materials. Soils with Permian black rock series as parent materials exhibit notably higher selenium content, with an enrichment coefficient of 3.74. In high-selenium-content areas, rice, radish, and cabbage exhibit selenium enrichment rates exceeding 65%. Except for potatoes, crops display positive correlations between their selenium content and the selenium content in their root soils, with tea showing the highest correlation (P<0.01, R=0.84). This suggests a close relationship between the selenium content in crops and their root soils. The crops in cultivated areas with Permian black rock series and Triassic carbonate rock series as soil-forming parent materials exhibit high bioconcentration factors of selenium, with soils and crops with Permian black rock series as soil-forming parent materials presenting the highest average selenium content. This highlights the significant impacts of soil-forming parent materials on crop selenium content.

Despite bearing valuable recyclable elements, mine tailings pose environmental risks. However, there is a lack of studies on the geochemical characteristics of tailings in China and abroad, hindering their appropriate treatment and reuse. This study collected tailing samples from the Han-Xing Iron deposit in Hebei Province, China and conducted the analysis and tests of these samples. This study determined the concentrations and chemical speciation (i.e., exchangeable, carbonate-bound, Fe-Mn oxide-bound, organic-bound, and residual forms) of elements including Fe, Co, S, Cu, and Zn in tailing particles with varying grain sizes. Accordingly, it explored the implications for the exploitation and utilization of tailing resources, along with the assessment of environmental risks. This study provides deeper insights into the geochemical characteristics of tailings, producing positive impacts on the exploitation and utilization of tailing resources, as well as the prevention of environmental risks.

As an important part of gravity investigation, the performance tests of gravimeters are required throughout field surveys. In these tests, mean squared error (MSE), accuracy, and root mean squared error (RMSE) are commonly employedto quantitatively describe the test results. The comparison of the theoretical equations for dynamic and consistency tests in specifications on geological surveys, petroleum, and measurement reveals a pronounced confusion in the usage of MSE, accuracy, and RMSE. This issue is observed in the consistent equations forconsistency testsin these specifications. Through investigations into the equations used in the dynamic and consistency tests inthe threespecifications, this study analyzed the differences between mean MSE and RMSE, elucidated the normativity of RMSE relative to MSE, and determined the applicablerange of RMSE. To avoid confusion, it is recommended that accuracy be used for qualitative expression and RMSE for quantitative expression in these specifications.

Small- and micro-scale faults fractures (fractures and faults with fault throw less than 10 m) that originally developed in shale strata have a significant impact on the probability of penetration, stimulation volume, and production capacity of high-quality reservoirs in horizontal well sections. Therefore, it is critical to conduct fine-scale fault and fracture prediction. However, any single method struggles to accurately identify and predict these faults and fractures. Based on the developmental conditions of small-and micro-scale faults and fractures in the shale gas reservoirs of the Longmaxi Formation in the southern Sichuan Basin, this study conducted forward modeling, response mechanism analysis, and characterization of fracture responses, developing a prediction method integrating predicting and modeling. Furthermore, this study preferentially investigated techniques including seismic data processing, small-scale fault and fracture prediction, multi-scale fracture modeling, and fusion characterization. The results of the proposed method were highly consistent with the geological anomalies including small and micro-scale faults, lost circulation, and inter-well pressure channeling observed during the drilling of horizontal wells in the shale gas reservoirs of the Longmaxi Formation. Furthermore, these results exhibit a strong positive correlation with the single-well production capacity. All these corroborate that it is feasible to use this method to predict small- and micro-scale faults and fractures. This study can serve as a reference for predicting small-scale faults and fractures in other strata of the same type.

Seismic data collected in the field frequently suffer from missing values due to constraints of acquisition cost or terrain. Data reconstruction is a critical step in seismic data preprocessing. Based on the compressed sensing theoretical framework, this study subsampled synthesized data using the 2D random undersampling technique. Then, the 3D seismic data were divided into a series of time slices. By introducing the sparse Shearlet transform and using the convex set projection (POCS) algorithm, this study conducted sequential data reconstruction for various time slices. As a result, a Shearlet transform-based time-domain 3D seismic data reconstruction method was developed. Numerical experiments and measured results demonstrate that the proposed reconstruction method exhibits a higher signal-to-noise ratio, a higher computational speed, and better effects than a Curvelet transform-based approach.

Conventional inversion and forward modeling of large-scale potential field data from gravity and magnetic exploration, demanding high computer performance, exhibit low efficiency. Hence, this study defined a footprint determination method for potential fields, analyzed the influencing factors, and innovatively proposed a footprint-FFT strategy for forward modeling of potential fields. The footprint-FFT algorithm improved the forward modeling process from three aspects: (1) Kernel matrices were calculated based on the potential field-derived properties, significantly reducing their size; (2) A footprint concept for potential fields was introduced and defined, decoupling data scales from kernel matrix sizes, thus improving the kernel matrix computing efficiency and reducing the hardware cost; (3) Based on the above, the computing area was divided into subspaces, and the footprint-FFT strategy was first proposed for the batch computing of potential fields in subspaces, accelerating the forward modeling process. By reducing the computational complexity and storage of the kernel matrix, the method proposed in this study significantly improved the operational speed while ensuring computational accuracy. This method enabled the fast forward modeling of potential fields with more than 1 billion grids on a laptop computer within a few minutes. Theoretical examples demonstrate that this method has high efficiency and moderate requirements for computer configuration, manifesting considerable potential in the forward modeling and inversion of large-scale potential field data.

The inversion of petrophysical data can image the microscopic fracture structures inside rocks, revealing the evolutionary patterns of fractures within rocks and soil with changes in external environments. Hence, it is an intuitive and reliable method for investigating the mechanisms of deep geotechnical disasters. This study presented a petrophysical data acquisition system and resistivity-based forward modeling and inversion algorithms. Based on the above, this study conducted numerical simulations of 2D and 3D inversion imaging of petrophysical data. As indicated by the numerical simulation results, 2D inversion imaging can characterize millimeter-scale rock fractures with high/low resistivities, whereas 3D inversion imaging can accurately locate and effectively identify millimeter-scale fractures and vugs with high/low resistivities. Moreover, data measurement and inversion imaging were conducted on rock samples subjected to microwave-induced fracturing in three states: heated sandstone before failure, sandstone heated to a molten state, and molten sandstone in a cooled state, preliminarily revealing the variation patterns of sandstone fractures under microwave heating. Overall, this study provides a novel method for exploring the mechanisms of deep geotechnical disasters.

To determine the optimal prospecting target in the Bishan area, Xianghuang Banner, Inner Mongolia, this study conducted a geochemical survey at 1∶10,000 scale. Using multivariable statistical analysis, this study analyzed 14 elements (i.e., Au, Ag, Cu, Pb, Zn, Mn, Mo, Li, W, Sb, Bi, B, Hg, and As) in soil samples from the study area. The results indicate that six elements, including Au, Ag, Pb, Zn, Li, and As, exhibited high enrichment degrees, suggesting their significant metallogenic potential. The anomalies of high-content elements are principally dictated by the outer contact zone between tuffs/tuffaceous volcanic breccias and granites in the Lower Permian Sanmianjing Formation. The ore-forming elements are primarily controlled by the NW-trending fault zone. Alterations like silicification, binarite, pyrite, galena, and sphalerite alterations serve as principal prospecting markers. Based on the geological conditions for mineralization in the Bishan area, this study delineated three composite anomalies and two prospecting targets, with Ag ore bodies discovered through engineering validation. Soil geochemistry proves crucial for the successful identification of polymetallic ore bodies, thereby providing a significant foundation for subsequent mineral exploration efforts.

To improve the inversion accuracy of reservoirs in the Paleogene strata with limited wells and sedimentary and structural complexity, two key technologies were used in seismic data processing: sparse pulse inversion for primary wave estimation and anisotropic Q-pre-stack depth migration (PSDM). This contributed to improved quality of seismic gathers and imaging. Then, the pre-stack simultaneous inversion method was applied as follows: (1) Stacking velocity and layer-constrained Dix inversion were employed to obtain a low-frequency model of P-wave impedance; (2) Elastic impedance inversion was performed using angle-stacked data and well-calibrated wavelets, yielding far, medium, and near elastic impedance; (3) Initial P- and S-wave impedance, as well as initial density, were obtained through Fatti inversion; (4) Pre-stack simultaneous inversion was performed to obtain the final P- and S-wave impedance and density; (5) Lithology and physical property inversion results were used to predict the reservoir distribution range. This method, driven by three-dimensional seismic data and exhibiting low dependence on logs, can serve as a reference for reservoir prediction under similar geological settings.

Land emerges as the most fundamental resource for agricultural production, and addressing land quality-related issues is the key to ensuring high food quality. A comprehensive understanding of land quality is crucial to the scientific and sustainable utilization and development of land resources. This study conducted a 1:50,000 geochemical survey of land quality in the contiguous farmland in Dongchuan Town, Yao'an County, Yunnan Province. Accordingly, this study provided a comprehensive assessment of soil nutrients, environment, dry and wet atmospheric deposits, and agricultural irrigation water. Based on the assessment results, this study determined the production areas of green food and pollution-free agricultural products, aiming to provide a reference for the development and utilization of sustainable, green cultivated land. The results indicate that soils in the study area are nutrient-rich and enjoy a favorable environment, high-quality irrigation water, and an excellent atmospheric environment. The comprehensive grade assessment results of soil quality align with those of land quality, revealing that the first and second-grade high-quality soils account for 68.98% of the total area. A batch of production areas of pollution-free and green food were determined, and those that can be directly used to develop green, zinc- and copper-rich crops were delineated. These findings will provide geochemical data support for land use planning, food security, building agricultural products with plateau characteristics, and serving rural revitalization efforts.

Slope tomography is a method to estimate subsurface velocity macromodels from the slopes and traveltimes of local coherent reflection events. In geologically complex areas, the macromodels obtained from slope tomography tend to yield larger errors. To address this issue, this study proposed a method for error correction of the models using deep learning. Specifically, with macromodels determined using slope tomography-based inversion serving as input and corresponding theoretical models as labels, a neural network was trained, yielding a nonlinear mapping from the slope tomography-derived macromodel to the corresponding theoretical model. To ensure that the trained neural network was applicable to measured seismic data, the training samples were generated from the inversion model and migration profiles of measured seismic data. Tests based on the data synthesized using the theoratical model validated the accuracy and effectiveness of the proposed method. The proposed method was then applied to the 2D measured seismic data from beaches and shallow seas, yielding velocity models with elevated precision and depth migration imaging profiles with high quality.

In actual exploration, the surface-to-borehole transient electromagnetic (TEM) method is prone to be affected by irregular transmitter loops and inclined boreholes, resulting in increased measurement errors of the three-component induced magnetic fields and decreased interpretation accuracy. By establishing surface-to-borehole TEM method-based three-component measurement models under the excitement of transmitter loops of various shapes, this study derived the calculation formulas for surface-to-borehole TEM responses under inclined boreholes through coordinate transformation. Then, it achieved one-dimensional forward modeling of the full-space TEM field using a numerical filtering algorithm. The calculation results of multiple typical models indicate that the three components of the transient magnetic fields were significantly influenced by the shapes of the transmitter loops, with the impacts on horizontal components x and y far more significant than those on vertical component z. The transmitter loops of regular polygons with even edges as the sources exhibited uniform and symmetric distribution of the TEM fields of the three components. Under the condition of the same perimeter, a greater number of edges of the transmitter loops associated with greater primary field energy excited by the loops. Therefore, rectangular transmitter loops as the sources prove the most cost-effective. The inclination and offset primarily affected the amplitude of the three-component responses. In contrast, the borehole azimuth mainly influenced the sign of the horizontal components, bearing rich information on location. Therefore, in the exploration using the surface-to-borehole TEM method, it is necessary to accurately determine source paths and the geometric morphologies of boreholes to make essential corrections, thus improving the accuracy and reliability of interpretations.

Areas with low exploration degrees in the Tarim Basin exhibit intricate seismic-geologic conditions and extensively developed multiples.The internal multiples generated by strong reflection interfaces involving Paleozoic gypsum rocks undermine the imaging of the Ordovician stratigraphic information,resulting in vague images for Ordovician fractured-vuggy carbonate reservoirs and thus affecting stratigraphic interpretation.Accurate prediction and suppression of internal multiples in the Yubei area is challenging,thus restricting the deployment of oil and gas exploration in the area.The conventional prediction method for internal multiples is computationally intensive and ineffective.Hence,this study proposed an internal multiples suppression technique combined with the modeling method and adaptive matching subtraction.Based on the principles of internal multiples prediction and the forward modeling results,the proposed technique takes the main reflection interfaces generating internal multiples as the model layers and follows the approach of layer-by-layer prediction and suppression.Finally,it employs adaptive matching subtraction for the suppression of internal multiples.As demonstrated by the processing results of actual data,the proposed technique can effectively predict and suppress the dominant internal multiples to eliminate their interference effects.It solves the problems of layer-crossing phenomenon and flat formation occurrence,improving the imaging accuracy of formation structures,faults,and fractured-vuggy reservoirs.

This study investigates the spatial distribution characteristics, temporal changes, and influencing factors of total carbon density, organic carbon density, and reserves in the farmland soils in Luoyang City based on repeated sampling data from multi-purpose regional geochemical survey points over different periods. The results indicate that in 2005, the topsoils in the multi-purpose survey area exhibited an average total carbon content of 1.57%, an average total carbon density of 44.74 t/hm², an average organic carbon content of 1.12%, and an average organic carbon density of 34.27 t/hm². With annual average increases in the total carbon density and organic carbon density of 0.709 t/hm² and 6.643 t/hm², respectively, this year witnessed increases in the total carbon and organic carbon of 41.73 kg/(hm²·a) and 390.75 kg/(hm²·a), respectively. The respective reserves of total carbon and organic carbon were 12.511 3 million tons and 8.879 59 million tons, with respective increases of 198.28 thousand tons and 1.857 8 million tons. In 2018, the topsoils in the multi-purpose survey area displayed an average total carbon content of 1.18%, an average total carbon density of 34.27 t/hm², an average organic carbon content of 1.07%, and an average organic carbon density of 30.94 t/hm². With annual average increases in the total carbon density and organic carbon density of 9.642 t/hm² and 4.727 t/hm², respectively, this year witnessed increases in the total carbon and organic carbon of -2,410.5 kg/(hm²·a) and 1,181.75 kg/(hm²·a), respectively. The respective reserves of total carbon and organic carbon were 1.963 5 million tons and 1.772 61 million tons. The total carbon reserves in topsoils in the whole study area were 14.474 81 million tons, including organic carbon reserves of 10.652 2 million tons. The total carbon reserves decreased by 552.41 thousand tons, while the organic carbon reserve increased by 270.82 thousand tons. Overall, the study area experienced a total carbon decrease of 354.13 thousand tons and an increase in the organic carbon reserves of 2.128 62 million tons. The total carbon showed significant positive correlations with the contents of organic carbon, CaO, MgO, N, and P, the organic carbon displayed significant positive correlations with the contents of total carbon, N, and P, and there was a significant positive correlation between pH and the CaO content. Fertilization led to an increase in the organic carbon and total carbon contents in farmland soils, with total carbon being significantly affected by the CaO content. In the carbonate areas, alkaline soil environments exhibited carbon sink characteristics. In the southern regions with acidified soil environments, the decomposition of carbonates in soils led to carbon loss and reduced calcium content. The results of this study provide important scientific evidence for research on peak carbon dioxide emissions and carbon neutrality of Luoyang City.

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

Based on high-precision, high-quality data on SiO₂, Al₂O₃, Fe₂O₃, and organic matter in topsoils obtained from the 1:250,000-scale multi-purpose regional geochemical survey in Fujian Province, this study assessed topsoils and, for the first time, established a geochemical method-based geochemical assessment system for desertified land in the province. Specifically, this system involves methods for calculating the silicon-aluminum-iron ratio (Saf), carbon-silicon ratio (K_Si), and their comprehensive index value (Szh_ f), which serves as the indicator for assessing the degree of land desertification. Specifically, a higher Szh_ f value indicates a higher degree of desertification, and vice versa. Furthermore, this study determined the statistics of geochemical classification parameters for desertified land in Fujian Province and delineated the distribution ranges of geochemical grades. This aims to assess the current status of desertified land in the province from the microscopic perspective of soil elements and to further ascertain the distribution characteristics of the land. The results indicate that the land with strong, moderate, slight, and very slight desertification in Fujian Province exhibits areas of 39 531 hectares (0.326%), 65,790 hectares (0.542%), 103 601 hectares (0.853%), and 360 329 hectares (2.968%), respectively, primarily distributed along the coastal zone to the south of the Minjiang River and in Changting County of Longyan City. Field verification demonstrates that this evaluation method is scientific and reliable and yields accurate classification results of desertification grades, thus objectively reflecting the distribution status of desertified land in Fujian Province.

The construction and presentation of a geological modelprove to be ahot topic and challenge in research on 3D geological modelling. Given the large scale, involvement of complex surfaces, and insufficient geological constraints of geological body data, this study achieved the rapid construction of a large-scale geological surface model using the domain decomposition-based implicit generation method. Initially, implicit functionswere constructed by taking radial basis functions as the kernel functions.Then, the distribution functions of various domainswere solved in parallel usinganoverlapping domain decompositionmethod, reducing the spatiotemporalcost and accelerating the solving process.Subsequently, normal vectors were extracted to generate control pointsand formconstraints on surface fluctuation, thereby effectively controlling the model boundaries. The experimental results indicate that the method proposed in this study can significantly improve the efficiency associated with the solving of distribution functionswhile ensuring the high quality of the model. This study effectively solves the problem of balance between efficiency and precision in geological modeling and provides methodological support for the refinement of geological surfaces.

Ray tracing-based first-arrival traveltime tomography is widely used to construct near-surface velocity models to achieve the static correction of seismic data from complex near surface.However,this method necessitates the calculation of ray paths for first-arrival traveltimes and the iterative updating of initial velocity models.As a result,significant computational time is required when applying this method to measured 3D high-density seismic data.To address this issue,this study proposed a method for quickly building 3D near-surface velocity models utilizing diving wave traveltimes under rugged surface.Specifically,based on the ray and traveltime equations of diving waves corresponding to velocities subjected to lateral and vertical changes under rugged surface,the velocity distribution from the observation surface downward was determined using common offset gathers.The proposed method eliminates the need for ray tracing and iterative updates of initial velocity models,offering high modeling efficiency.Tests based on data from theoretical models verified the effectiveness of the proposed method.When applied to measured 3D seismic data,the proposed method yielded static correction results comparable to those obtained using the Fresnel-volume first-arrival traveltime tomography while significantly improving computational efficiency.

The topographic factor significantly influences the 3D inversion results of magnetotelluric data. Despite extensive research results previously obtained in suppressing topographic effects, the gridding of complex terrains (with significant elevation changes) is still challenged by grid design complexity and difficulty in correcting data elevation points. Based on the mainstream 3D inversion module ModEM for magnetotelluric data, this study proposed a novel method for rapid automatic grid design and partitioning of terrains based on unsupervised learning, primarily involving the K-means++ algorithm and the assessment of clustering effects. Compared to the uniform and equal proportion-based hierarchical methods ignoring the topographic factor, the proposed method shows the following advantages: (1) The terrain grid generated by the clustering-based hierarchical method manifested higher terrain approximation, reducing the average error between the terrain grid and the actual terrain by 25%; (2) The matching calculation for terrain correction based on the digital elevation model was somewhat avoided; (3) The rapid design of terrain grids can be achieved, and the hierarchical characteristics can be referenced for gridding in other modeling software. The proposed method was employed to demonstrate the whole process of partitioning the elevation data of a complex terrain in a mining area, generating a resistivity structure model more representative of the actual terrain characteristics. Based on this model, finer-scale 3D inversion results were obtained. Theoretical and practical applications illustrate that the proposed method can significantly improve the topographic adaptability of gridding, holding critical significance for suppressing topographic effects on the 3D inversion of magnetotelluric data.

In the era of rapid digitalization development, artificial intelligence (AI) technology has brought revolutionary changes to traditional work patterns. Based on Baidu Comate, this study proposed an automatic numbering method for sampling points in irregular geochemical networks. Automatic numbering tests, conducted on 12 000 geochemical sampling points, demonstrate that the method improved the efficiency by 99.8% and achieved 100% accuracy compared to the traditional manual method. This indicates that the proposed method is more efficient and accurate than traditional approaches, effectively avoiding human errors and improving work efficiency. This study also discussed the challenges AI faces in processing complex instructions, the importance of instruction clarity, the identification of complex logic, and the necessity of developing knowledge reserves. Although AI technology has significantly improved the efficiency and accuracy of the automatic numbering of sampling points in irregular geochemical networks, the early development of packaging tools requires personnel who can read codes to modify and verify the codes. Additionally, AI-assisted demand processing should be in phases, and ultimately, it is necessary to encapsulate verified codes into a tool for reuse.

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

Noise detection and suppression of oil well pumping units pose challenges in data processing for mature exploration areas.The conventional method in the industry is to identify pumping unit noise through manual interactions and then suppress it as high-amplitude interference.However,manual identification wastes manpower and yields low detection accuracy,often resulting in missed detections.Hence,based on the noise characteristics of pumping units,this study conducted noise detection on seismic data containing pumping unit noise using deep learning methods.It then estimated the bandwidth of the detected noise using mathematical morphology techniques to determine the final position and distribution pattern of the noise.This allows for adaptive parameter support for the anomalous amplitude attenuation(AAA) method to achieve automatic detection and efficient suppression of pumping unit noise.The processing results of actual seismic data reveal that the methodology used in this study enables intelligent detection of pumping unit noise,significantly reducing the manual effort required for noise identification,improving the detection accuracy,and enhancing the fidelity and robustness of the AAA method.

The spectral parameters of the Cole-Cole model can improve the resolution of comprehensive interpretation of time-domain induced polarization (IP) data, contributing somewhat to the exploration of metal deposits. Applying the backpropagation neural network (BPNN) model to the prediction and inversion of spectral parameters can avoid high computational complexity to improve the inversion speed. Moreover, the BPNN model can fully explore the utilization efficiency of time-domain IP data to enrich the characteristic information of subsurface ore bodies. Based on this, this study derived the mathematical expression of the time-domain apparent polarizability attenuation curve using the digital filtering algorithm. With the mathematical expression as the forward/inverse model, this study comparatively analyzed the impacts of four factors-the sample size of the training set, the number of neurons in the input layer, the node number of hidden layers, and the number of hidden layers-on the training and inversion effects of the BPNN model, determining the optimal model. Furthermore, this study trained the BPNN model using time-domain IP data from eight time windows. Finally, this study applied the trained BPNN model for prediction and inversion based on the measured time-domain IP data. The results indicate that the BPNN model is feasible in inverting spectral parameters based on both theoretical and measured datasets, manifesting high inversion accuracy and minor errors. Overall, the results of this study can assist in distinguishing paragenetic and associated minerals and reducing misinterpretation.

Due to numerous thin interbeds in weakly elastic media,seismic excitation typically yields rapidly attenuated seismic wave energy and a narrow dominant frequency band,resulting in low-resolution seismic data.Therefore,selecting a favorable lithology plays a crucial role in improving the seismic excitation effect.This study explored the dominant factors influencing the quality of seismic data obtained from the northern Jiangsu exploration area,a region with a dense river system.Specifically,this study determined the top boundary of the high-velocity layer based on microlog surveys and the dominant lithologic member using the cone penetration test and lithologic coring.It quantitatively analyzed seismic wavelet attributes,including octave band,resolution,main-to-side lobe energy ratio,and wavelet clarity,establishing their matching relationship with the lithology for seismic excitation.By selecting a lithologic surface featuring a high seismic wave propagation velocity,a favorable elastic property,and a wide frequency band in the study area,it plotted a surface lithology map for pointwise well depth design,ensuring wide-frequency excitation.The above techniques were applied to well depth design for seismic excitation in the YA and SDX areas,achieving well-normalized single-shot frequencies and widening the dominant frequency band of the target layer in the seismic profile by over 10 Hz,with an increase of 1.5 octave bands.The results show that the excitation strategy of "selecting the dominant lithology from weakly elastic media" in regions with dense river systems can effectively enhance the seismic excitation effect in weakly elastic media,thereby improving the imaging accuracy and resolution of seismic data.

To understand the characteristics and sources of heavy metal contamination in the sediments of the Jinsha River basin, this study investigated the Qingling River basin-a primary tributary of Longchuan River on the south bank of the Jinsha River. Samples were collected from the sediments of 22 representative sections, and the concentrations of eight heavy metal elements, i.e., As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, were tested and analyzed. Statistical analysis was conducted on the distribution characteristics of these heavy metal elements in the sediments along the basin. The sources of these heavy metals were investigated using correlation analysis and principal component analysis, and the degree of heavy metal contamination in the sediments was assessed using the geo-accumulation index and the Nemero index. The results indicate that As, Cd, Cu, Hg, Ni, Pb, and Zn are primarily influenced by mining, agricultural, and industrial activities. Cr and Ni originate primarily from soil-forming parent materials. Besides natural sources, Ni is also affected by anthropogenic sources. The assessment results derived using the geo-accumulation and Nemero indices reveal that the eight heavy metal elements exhibit moderate or low contamination on average. However, partial elements, represented by Cd, Hg, Pb, and Zn, exhibit localized enrichment within the basin, primarily concentrated in the Laojiezi Au-Pb-Ag polymetallic mining area and the urban-rural junction in the lower reaches of the county.

Traditional gridding methods struggle to balance computational accuracy and efficiency when processing irregularly distributed magnetic anomaly data. To address this issue, this study applied the classic least-squares collocation method from geodesy to the gridding of ground-based magnetic anomaly data. This application was verified through the test and analysis of the simulation data and the actual coalfield data. The results indicate that the computational accuracy of gridding based on least-squares collocation is dictated by the error estimation of discrete observational data and the selection and fitting of the covariance function. More accurate error estimation contributes to higher-accuracy interpolation. A polynomial function is a simple and effective empirical covariance function for processing magnetic anomaly data. The least-squares collocation method demonstrates more effective noise suppression compared to the Kriging, minimum curvature, and radial basis function methods. Overall, applying the least-squares collocation to the gridding of magnetic anomaly data can enhance the accuracy and efficiency of data processing.

Seismic waves, particularly their high-frequency components, will undergo energy attenuation during subsurface propagation. This results in a low signal-to-noise ratio (SNR) within the high-frequency band, significantly reducing the accuracy of seismic exploration for deep oil and gas. To enhance the SNR of deep seismic data, this study employed the time-frequency analysis technique to describe the time variations of signal frequency based on the non-stationary characteristics of seismic signals. Accordingly, this study proposed a method for suppressing deep high-frequency noise based on time-frequency analysis. Considering the stable and similar time-frequency characteristics of effective signals and the uncertain and random high-frequency interference, this study proposed an adaptive threshold selection strategy based on correlation analysis. This strategy involves extracting the time-frequency characteristics of effective signals from an advantageous frequency band and comparing them with the time-frequency characteristics within the high-frequency band. Subsequently, feature-constrained attenuation was applied to time-frequency spectra in the high-frequency band, thereby suppressing high-frequency noise. Theoretical models and actual data processing results demonstrate that the proposed method can effectively suppress high-frequency noise and significantly enhance the SNR of deep seismic data.

AVO inversion, based on the Zoeppritz equation, extracts various hidden petrophysical parameters from pre-stack seismic data. In seismic data, angle information is recorded in the form of offset values, and converting between offset values and angles is prone to generate errors. In addition, using the same approximate formula for different acreage types may lead to reduced applicability due to varying actual geological conditions. The exact Zoeppritz equation will lead to increased computational demands due to its high complexity. Therefore, this study developed an adaptive prestack inversion method based on the quadratic Encoder-Decoder network. This inversion method used the high feature and relationship extraction abilities of deep learning to replace traditional relationships, thereby reducing the angle errors and adapting to varying acreage types and geological conditions. The quadratic Encoder-Decoder network used a quadratic algorithm as the optimization method, maximizing the efficiency of the standard Encoder-Decoder structure. Additionally, the Xavier initialization method was incorporated to enhance the randomness of model initialization, thus improving the robustness of the network. The results indicate that the quadratic Encoder-Decoder network, selected through orthogonal experiments, outperforms the single-decoder network in prediction and exhibits greater consistency with actual log curves. The P-wave velocity, S-wave velocity, and density profiles obtained from inversion are consistent with the geological conditions of the study area, exhibit strong lateral continuity, and can effectively achieve high-precision prestack inversion.

To investigate the contamination, source, and ecological risk of soil heavy metals in a typical industrial town in Shandong Province, China, this study collected 499 topsoil samples from the study area from August to October 2022. The contents and spatial distributions of heavy metals like Hg, Cd, As, Pb, Cu, Cr, Zn, and Ni in the samples were analyzed using classical statistics and spatial interpolation methods. The source apportionment of heavy metals in the study area was explored through the principal component analysis (PCA). The contamination levels of heavy metals in the study area were assessed using the contamination index method. The results indicate that the average contents of Hg, Cd, As, and Pb in soils all exceeded their background values in Yantai City, and high-value zones were observed for all eight elements, indicating various degrees of enrichment. The analysis of coefficients of variation reveals that except for Ni, other heavy metals were significantly influenced by human activities. The PCA suggests that Cd, Pb, Cu, Zn, and Cr originated primarily from industrial and traffic sources. As and Hg were predominantly derived from industrial, agricultural, and domestic sources, while Ni was primarily from natural soil parent materials. The analyses based on the single-factor contamination index, geoaccumulation index, and Nemerow contamination index show that apart from Hg and Cd, other soil heavy metals in the study area exhibited no or slight contamination overall, demonstrating that the study area was principally contaminated by Hg and Cd. The potential ecological risk assessment suggests that the overall heavy metal contamination posed a minor risk level. A few sites with relatively severe contamination were primarily located around the industrial area. The waste gas, wastewater, and industrial residue generated by industrial activities constituted the dominant factor influencing the enrichment of heavy metals in surrounding soils. Overall, soil heavy metal contamination in the study area was at a moderate to low level, with some metals, particularly Hg and Cd, severely exceeding standard levels, warranting attention. It is recommended to strengthen the monitoring of heavy metals in soils around the industrial area, and adopt scientific and reasonable measures to ensure sustainable soil utilization.

With the advancement of social economy and science and technology, the demand for oil and gas resources has been increasing in daily life and industry. Tight sandstone reservoirs have been the priority targets for the exploration and production of oil and gas resources. However, there still exist many challenges in assessing the parameters and quality of tight sandstone reservoirs. This study conducted experiments on the physical properties, pore structures, and electrical properties of rock samples from the Taiyuan Formation in the Shenmu gas field of the Ordos Basin. Based on this, it established a porosity-permeability relationship model, a capillary pressure prediction model, and a classification saturation assessment model. Besides, it obtained the relative permeability of gas and water phases, which varied point by point, from wells based on the I-Kr model. This study proposed the factors for assessing reservoir quality, which were applied to the target interval in the study area considering the physical properties, pore structures, and multiphase seepage capacity, yielding satisfactory assessment results. Therefore, the method of this study provides a reliable basis for the log-based assessment of the quality of tight sandstone reservoirs.