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  20 August 2025, Volume 49 Issue 4 Previous Issue   
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High-power-ultrahigh-power electromagnetic exploration technology: Progress and outlook
WANG Jun-Lu, CHEN Hui, LUO Xian-Zhong, ZHANG Xiao-Fei, LIN Pin-Rong, YU Bing, PANG Zhen-Shan
Geophysical and Geochemical Exploration. 2025, 49 (4): 755-767.   DOI: 10.11720/wtyht.2025.0178
Abstract   HTML ( 7 )   PDF (5690KB)

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.

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Extracting geological mineral information from regional geochemical exploration data: A case study of the Gaoqiao area in Huixian County, Gansu Province, China
TIAN Liao-Dong, LONG Deng-Hong, YANG Tao, LIU Hai, MA Min-Xiong, JIANG Hong-Ying
Geophysical and Geochemical Exploration. 2025, 49 (4): 768-777.   DOI: 10.11720/wtyht.2025.1267
Abstract   HTML ( 8 )   PDF (6159KB)

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.

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Soil geochemical characteristics and prospecting orientations in the Bishan area, Xianghuang Banner, Inner Mongolia
CHAI Chen-Hui, QIN Yue-Qiang, LI Peng-Yuan, XIN Kai, WANG Jian-Min, YIN Jia-Le, LI Chao-Qun, YUAN Ning-Bo, GUO Dong, SUN Yu-Fei
Geophysical and Geochemical Exploration. 2025, 49 (4): 778-789.   DOI: 10.11720/wtyht.2025.1382
Abstract   HTML ( 3 )   PDF (5190KB)

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.

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Genetic analysis of dolomites in the Sinian Dengying Formation on the periphery of the Huangling anticline, western Hubei Province
LI Hao-Han, ZHANG Cong, LI Wen-Zheng, ZHANG Chun-He, ZHANG Yuan, WANG Zi, CHEN Wei-Kun, FANG Rong-Hui
Geophysical and Geochemical Exploration. 2025, 49 (4): 790-801.   DOI: 10.11720/wtyht.2025.1346
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A suite of dolomite-dominated carbonate reservoirs is developed in the Sinian Dengying Formation in the Huangling anticline in the eastern part of the intracratonic rift, western Hubei Province. Investigating the formation environment and genetic mechanism of dolomites is crucial for determining the developmental mechanism of carbonate reservoirs and facilitating conventional oil and gas exploration in the study area. This study employed various analytical techniques, including cast thin sections, cathodoluminescence thin sections, field emission scanning electron microscopy, carbon and oxygen isotope analyses of carbonate rocks, major and trace element analyses, whole-rock mineral analyses, and determination of the degree of order of dolomite. Using these techniques, this study analyzed the chemical composition and mineralogical characteristics of dolomites from the Dengying Formation on the periphery of the Huangling anticline. Furthermore, this study explored the formation environment, developmental mechanism, and modification process of dolomites. The results indicate that the dolomites from the Dengying Formation contained the same proportions of CaO and MgO molecules and low Sr content, aligning with the characteristics of penecontemporaneous dolomites. The analytical results of trace elements and carbon and oxygen isotopes confirm that the dolomites formed in a marine environment with low Fe and Mn contents. The average paleoseawater salinity (Z) of 128.41, average temperature of 21.32 ℃, and average diagenetic temperature of 49.36 ℃ created the favorable environmental conditions for forming penecontemporaneous dolomites. Additionally, the dolomite from the Dengying Formation exhibited significantly lower δ18O compared to the Dengyingian seawater, degrees of order ranging from 0.61 to 0.99, and a peak frequency distribution between 0.8 and 0.9, indicating that the dolomite experienced a progressively deepening burial modification process. The whole-rock mineral analyses reveal that the content of dolomite was positively correlated with its degree of order, suggesting that a high degree of dolomitization corresponded to a higher degree of order during burial modification. Therefore, this study holds that dolomites in the Dengying Formation were originally formed by penecontemporaneous dolomite. Through prolonged burial modification, micritic dolomite with a low degree of order experienced recrystallization, gradually transitioning into very finely crystalline/finely crystalline dolomite, accompanied by an elevated degree of order. Ultimately, dolomites of a penecontemporaneous-burial modification origin formed in the study area.

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Geochemical exploration-based discovery of the Baiguo lithium-bearing porcelain stone deposit in Jiangxi Province, China
ZHANG Ming-Jun, YAN Xin-Hua, XIONG Guang-Qiang, LUO Xian-Ming, ZHU Wen-Hui, YE Yue-Chen
Geophysical and Geochemical Exploration. 2025, 49 (4): 802-809.   DOI: 10.11720/wtyht.2025.1375
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The Baiguo lithium-bearing porcelain stone deposit in Jiangxi Province, China is located in the southern Jiuling uplift within the Jiuling rare metal metallogenic belt. This large altered granite-hosted lithium-bearing porcelain stone deposit was discovered by the Geophysical and Geochemical Exploration Brigade of Jiangxi Bureau of Geology using geochemical exploration methods and assessed using geological methods. The prospecting process in this study involved the following aspects: identifying the potential prospecting area through regional geochemical exploration, pinpointing the prospecting target based on the 1∶50,000 stream sediment survey, delineating the lithium anomaly range and morphology based on the 1∶10,000 soil survey, determining the cause of anomalies through follow-up geochemical surveys, defining the spatial distributions of ore bodies through trenching exploration and drilling engineering, and ascertaining the occurrence state and selectivity of lithium based on experimental tests. This prospecting process demonstrates the fast, direct, cost-effective, and efficient characteristics of geochemical exploration methods and their superiority and significance in mineral exploration. Notably, to achieve satisfactory prospecting results, the geochemical exploration for lithium should attach great importance to the geochemical enrichment patterns of lithium, the scientific interpretation of anomalies, and the close association with geological work.

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Characteristics and prospecting application of soil radon in a uranium mining area, Xingyi City, China
CHENG Jun-Yi, PENG Song, FAN Yun-Fei, LU Ping, CHEN Xiu-Wang
Geophysical and Geochemical Exploration. 2025, 49 (4): 810-817.   DOI: 10.11720/wtyht.2025.1459
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This study aims to further clarify the characteristics of uranium deposits and faults in a uranium mining area in Xingyi City, thereby laying a solid foundation for subsequent drilling operations. Soil radon measurements were conducted using the FD216 environmental radon meter. The data obtained were analyzed comprehensively to determine the content and distribution of radon in the soil, delineate the anomaly halos of soil radon, and refine the properties of concealed faults. Furthermore, the metallogenic characteristics of uranium deposits were examined, combined with geological and geochemical exploration data. This study revealed a strong correlation between soil radon content and fault strike. The most significant radon anomaly zones are located in the southwest and central-northeast sides. Uranium deposits in the study area occur in fault fracture zones and are associated with strata. The uranium exploration target might be located within the fault zone in the first member of the Middle-Lower Triassic Jialingjiang Formation.

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Anomaly characteristics in gamma-ray spectra and their relationship with uranium mineralization for target layers in carbonaceous-siliceous-argillaceous rock-hosted uranium deposits in Shitai area, Anhui Province, China
ZHOU Qian, LIU Chen-Chen, YANG Biao, FANG Xiang-Yu, ZHOU Zhong-Ping
Geophysical and Geochemical Exploration. 2025, 49 (4): 818-825.   DOI: 10.11720/wtyht.2025.1317
Abstract   HTML ( 1 )   PDF (5836KB)

The Shitai area in southern Anhui Province, China is located in the eastern part of the Xiushui-Ningguo carbonaceous-siliceous-argillaceous rock-hosted uranium metallogenic belt. The frequent activity of fault structures in this area contributes to great uranium mineralization potential. To explore the uranium resource potential in the Shitai area, this study conducted 1∶50 000 ground-based gamma-ray spectrometry. Accordingly, this study extracted metallogenic information using traditional statistical methods and difference analysis of uranium content, followed by the analysis of the distribution characteristics of radioactive elements. Then, this study analyzed the radioactive anomalies in the four members of the Hetang Formation based on the spectra and geological profiles. The analytical results revealed that the highest uranium content occurs in the first member of the Hetang Formation. By combining field geological surveys and microscopic petrographic analyses, this study further investigated the geological characteristics of the first member, as well as their potential relationships with uranium mineralization. The results indicate that the Hetang Formation serves as the primary uranium source in the Shitai area, with its first member identified as the main ore-bearing layer. This member is rich in ore-forming materials including organic matter, clay minerals, and pyrite, creating favorable conditions for uranium enrichment. The in-depth research on the target layer will provide technical guidance for exploring the same type of uranium deposits in this area.

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A method for predicting the brittleness and fracture parameters of shale gas reservoirs based on prestack direct inversion
SHI Xue-Wen, WANG Chang, ZHANG Dong-Jun, FENG Yan-Wen
Geophysical and Geochemical Exploration. 2025, 49 (4): 826-837.   DOI: 10.11720/wtyht.2025.1506
Abstract   HTML ( 1 )   PDF (13517KB)

The conventional inversion of anisotropic media is often constrained by assumptions of narrow-angle incidence and weak changes in stratigraphic properties.Moreover,the prediction of rock elastic parameters typically involves linear inversion and indirect fitting,leading to less accurate and reliable inversion results of petrophysical parameters for anisotropic formations.Hence,this study derived the petrophysical models of Young's modulus,Poisson's ratio,and fracture parameters for vertical transverse isotropy(VTI) media.Based on the precise VTI reflection coefficient equation,this study proposed a Bayesian anisotropic nonlinear direct inversion method,constrained by the L1 norm,to predict the brittleness and fracture parameters of shale gas reservoirs through direct inversion.The proposed method yielded satisfactory application results in a study area of shale gas in Southwest China,offering a novel technique for characterizing shale gas reservoirs.

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Structure-oriented log-seismic error correction in prestack depth migration
WANG Bing-Gang, DING Cheng-Zhen, ZHANG Dan, DONG Qing-Yu, CHEN Xin, WANG Ze, YANG Yang, XUAN Rui-Qing
Geophysical and Geochemical Exploration. 2025, 49 (4): 838-845.   DOI: 10.11720/wtyht.2025.1451
Abstract   HTML ( 2 )   PDF (5711KB)

Log-seismic error correction serves as a primary method for determining Thomsen's compressional-wave anisotropic parameters of vertical transverse isotropy(VTI) media.This method is also an essential processing technique for obtaining accurate depth-migrated images.Conventional log-seismic error correction involves determining the log-seismic errors at well locations and then directly applying planar interpolation to correct the depths of seismic horizons.However,the conventional method can lead to structural distortions and anomalous values of anisotropic parameter δ in areas with significantly varying formation thicknesses.To address this issue,researchers typically manually edit and smooth the anisotropic parameter field and the anisotropic velocity field,consuming considerable manpower and time.Hence,this study proposed a structure-oriented log-seismic error correction method that incorporates the concept of log-seismic error coefficient.The proposed method utilizes formation thicknesses as constraints to perform planar interpolation for log-seismic errors.Moreover,it employs a strategy of sequential calculation and interpolation for log-seismic errors from shallow to deep formations.It yielded log-seismic error distribution values that better conform to formation thickness variations and more stable δ values,without anomalous values.Therefore,the proposed method effectively avoids structural distortions induced by log-seismic error correction while saving manpower and time in practical projects.

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Application of the seismic meme inversion method in predicting superimposed thin sandstones: A case study of the Gaotaizi oil layer in the Qian'an oilfield,southern Songliao Basin
YANG Guang, WANG Li-Xian, HU Jia, LIU Zhi-Jun, ZHANG Hong-Jie, WANG Yun-He, SUN Long, ZHANG Xu-Sheng, CHEN Yan-Hu
Geophysical and Geochemical Exploration. 2025, 49 (4): 846-854.   DOI: 10.11720/wtyht.2025.0040
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To address the challenges in predicting superimposed thin sandstones in lacustrine basins,this study proposed a technical workflow for their prediction using the seismic meme inversion(SMI) method.First,an initial inversion model was constructed using log curves from sample wells selected based on seismic waveform similarity.Second,the initial inversion model was iteratively optimized in a Bayesian framework to yield high-resolution SMI results.Third,the SMI results were integrated with low-frequency inversion results to yield high vertical resolution while effectively characterizing the lateral superimposed patterns and boundaries of sand bodies.Case studies demonstrate that the SMI method achieved a prediction accuracy of 2 m to 3 m for superimposed thin sandstones.The coincidence rates for calibration and validation wells reached 91.5 % and 85.2 %,respectively,confirming the effectiveness of the SMI method and the high precision of the inversion results.Overall,this study provides an effective technical approach to predicting superimposed thin sandstones in lacustrine basins.

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Reverse time migration of order-divided multiples based on seismic interferometry
ZHANG Hong, JIANG Da-Jian, LIU Xin, NIU Yun-Bo, LI Zhen-Chun, XU Kai
Geophysical and Geochemical Exploration. 2025, 49 (4): 855-868.   DOI: 10.11720/wtyht.2025.1137
Abstract   HTML ( 1 )   PDF (6601KB)

High-velocity salt domes and steeply dipping structures in subsurface media pose challenges to conventional imaging methods.In conventional seismic exploration,multiples are usually treated as noise to be suppressed or eliminated.However,due to their long propagation paths and smaller reflection angles within subsurface media,multiples show a wider imaging range and richer information on subsurface structures.Since seismic interferometry enables accurate prediction of multiples,the reverse time migration(RTM) of multiples based on seismic interferometry is crucial for imaging complex subsurface structures.Based on the analysis of the fundamental principles of seismic interferometry,this study derived the corresponding equations and algorithms.Furthermore,this study proposed a multiple prediction technique based on seismic interferometry.By circumventing conventional multiple processing methods,this technique enhances imaging efficiency, providing a research basis for subsequent RTM of multiples.To address the significant crosstalk noise in conventional RTM,this study innovatively utilized seismic interferometry to explore the RTM of order-divided multiples.Finally,this study proposed a RTM method for order-divided multiples based on seismic interferometry,effectively mitigating the problem of crosstalk noise in multiple imaging.Numerical experiments show that compared to the RTM of primary waves,the RTM of multiples exhibited significant improvements in imaging pre-salt structures.The RTM of order-divided multiples based on seismic interferometry could further suppress the crosstalk noise in conventional RTM,enabling accurate imaging of complex pre-salt structures and improving imaging resolution.

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Local imaging of complex structures based on seismic interferometry
DIAO Rui, GE Da-Ming, KONG Qing-Feng, YAN Xin-Yue, HAN Rui, GU Bing-Luo
Geophysical and Geochemical Exploration. 2025, 49 (4): 869-877.   DOI: 10.11720/wtyht.2025.1272
Abstract   HTML ( 1 )   PDF (7041KB)

With the continuous advancement of oil and gas exploration in China,the focus of seismic imaging has gradually shifted from large-scale overall imaging to small-scale complex structure imaging.Due to the inherent limitations of seismic wave propagation,small-scale and highly steep complex structures pose challenges such as difficulty in capturing interface reflection information and weak reflection energy.Consequently,conventional surface seismic imaging methods struggle to achieve accurate imaging of these targets.The seismic interferometry method can render the virtual observation system closer to the target area,improving the imaging resolution of complex interfaces, and achieving high-precision target-oriented imaging.This study conducted a theoretical derivation of the seismic interferometry mechanism and forward modeling of small-scale models.By comparing the generated interferometric gathers with actual reference gathers,this study verified the accuracy of the seismic interferometry method.Subsequently,this study applied the method to the backpropagation(BP) gas cloud model and a highly-steep structure- thin interbed model for numerical tests.The imaging results were finally compared with conventional reverse time migration(RTM) results,demonstrating that the seismic interferometry method enables high-precision imaging of deep complex structures.

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Source excitation characteristics of transient Rayleigh surface waves and the superposition and fusion of multi-dispersion spectra
CHEN Zhen-Hua, ZHANG Sheng-Biao, ZENG Qi-Yan, ZHANG Da-Zhou
Geophysical and Geochemical Exploration. 2025, 49 (4): 878-887.   DOI: 10.11720/wtyht.2025.1447
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Offset and source weight constitute critical factors influencing the data acquisition of transient Rayleigh surface waves. Hence, it is necessary to examine the characteristics of dispersion spectra derived from surface wave data acquired under different offsets and source weights. This study investigated the influence of the two critical factors on dispersion spectra through theoretical analysis and numerical simulation. Based on field experiments, this study delved into the characteristics of dispersion spectra from surface wave data collected at various excitation locations of seismic sources with different weights. To address the discrepancies in dispersion spectra caused by varying source locations during the data acquisition of transient surface waves, this study proposed a superposition and fusion method for multi-dispersion spectra, significantly enhancing the effectiveness of surface wave detection results.

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Application of time-frequency analysis in the suppression of deep high-frequency noise in the Penglai gas area
HAN Song, TANG Cong, ZHANG Xuan, ZENG Ming, PENG Hao-Tian, LYU Wen-Zheng, TU Zhi-Hui, LI Ke-Rui, ZHU Hai-Hua
Geophysical and Geochemical Exploration. 2025, 49 (4): 888-895.   DOI: 10.11720/wtyht.2025.2533
Abstract   HTML ( 0 )   PDF (7721KB)

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.

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A 3D inversion method for apparent resistivity data along irregular survey lines under complex terrain
GUO Jun-Qi, FAN Ben-Feng, LU Kai, WANG Peng, ZHAI Hao-Jie
Geophysical and Geochemical Exploration. 2025, 49 (4): 896-901.   DOI: 10.11720/wtyht.2025.1277
Abstract   HTML ( 3 )   PDF (3037KB)

The electrical resistivity tomography (ERT) method has become the primary geophysical technique for landslide structure investigation. However, the complex terrain of landslides and the impacts of collapsed surface features render it challenging to arrange survey lines orderly along a straight line in practice. This leads to deviations in the calculations of apparent resistivity. To minimize the impacts of irregular survey lines on the final results, this study developed a scheme for the 3D inversion of measured data. Specifically, this scheme minimized 3D grid subdivision by identifying the rectangle enclosing the minimum area of complete survey lines. Meanwhile, this scheme suppressed the changes in model parameters in the vertical direction by increasing the regularization parameters along the vertical direction of the survey lines. Numerical simulation results indicate that, compared to the traditional 2D inversion scheme, the proposed 3D inversion scheme can significantly improve the identification accuracy of the sliding zone. The measured results of the Baishuihe landslide have verified the effectiveness of the proposed method.

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Response characteristics of shallow good local conductors using the plane electromagnetic wave method
MA Hong-Wei, LIU Hai-Bo, LIU Peng-Fei, LIU Xiao-Yu, YAN Tuo-Jiang, LONG Xia
Geophysical and Geochemical Exploration. 2025, 49 (4): 902-911.   DOI: 10.11720/wtyht.2025.1270
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This study conducted the forward modeling of a 3D good conductor model under a uniform half-space background to investigate its response characteristics in a plane electromagnetic wave survey. The electromagnetic anomalies of a three-dimensional good conductor are primarily caused by the secondary field generated by static charge accumulated at interfaces. Consequently, higher relative resistivity differences between the target conductor and the surrounding rock correspond to greater response anomalies. Additionally, a smaller distance between observation electrodes and the target conductor is associated with greater relative response anomalies. Changes in the horizontal and vertical dimensions of a conductor pose different impacts of anomalies. Specifically, variations in vertical thickness have minor impacts on the anomalies. When a conductor has similar dimensions in the horizontal direction, its apparent resistivity response curve resembles a two-layer D-type sounding curve, with the relative anomalies intensifying as the horizontal sizes increase. However, in the case of significant differences between the two dimensions in the horizontal direction (with the larger dimension being at least eight times the smaller), the response curves observed in the directions of the larger and smaller dimensions differ. Notably, the apparent resistivity response curve observed in the direction of the larger dimension resembles a three-layer H-shaped sounding pattern characterized by high, low, and high values sequentially. In addition, the relative anomalies of apparent resistivity are generally more than two times those of phase, with apparent resistivity anomalies following the static effect law in the vertical direction. Specifically, apparent resistivity anomalies in high frequencies tend to extend to low frequencies, creating favorable conditions for anomaly identification. Therefore, apparent resistivity anomalies are more conducive to anomaly identification for good conductors.

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Development of a high-power time-domain induced polarization transmitter based on optimal absorption circuit
QIAN Wen-Sheng, XI Zhen-Zhu, ZHOU Sheng, QI Qing-Xin, XIAO Chang-An, WANG Jun, XUE Wen-Tao
Geophysical and Geochemical Exploration. 2025, 49 (4): 912-918.   DOI: 10.11720/wtyht.2025.1216
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Large-depth induced polarization sounding requires power supply with long wires and high current. This results in the oscillation of the turn-off waveforms, which greatly affect the accuracy of induced polarization (IP) measurement. To address this issue, this study first constructed a simulation model for electromagnetic induction caused by the long wires for high-power IP transmitters and proposed a method to eliminate IP electromagnetic coupling using an RCD absorption circuit. Then, using the optimal absorption circuit algorithm, the parameters of the optimal absorption circuit were calculated. Afterward, the optimal absorption circuit of the high-power 30 kW IP transmitter was designed, and the simulation results indicate that the optimal absorption circuit effectively mitigated the oscillation of turn-off waveforms. Finally, based on the optimal absorption circuit, a high-power IP transmitter prototype was developed. An AB/2 configuration with a large electrode spacing of 1 500 m was deployed in an area of Shanxi Province. The full turn-off waveforms at four measurement points were repeatedly observed under an emission current of 10 A. With a maximum standard deviation of polarizability estimated at 0.02, the accuracy of the transmitter met the requirements of relevant specifications.

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Feature identification model and seismic reservoir prediction of channel turbidite bodies: A case study of the MC block,Lower Congo Basin,West Africa
GAO Jun, XU Rui, HUANG Jia-Chen, YUAN Shu-Jin
Geophysical and Geochemical Exploration. 2025, 49 (4): 919-924.   DOI: 10.11720/wtyht.2025.0032
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A typical channel turbidite system is developed in the deep-water area of the Lower Congo Basin,West Africa,establishing this area as a significant target for deep-water oil and gas exploration.Turbidite bodies in this area are characterized by strong heterogeneity and a complex reservoir distribution.Traditional methods show limited turbidite body identification accuracy and reservoir prediction ability,failing to support efficient exploration.This study investigated the channel turbidite system in this area based on the deep-water gravity flow theory.It established feature identification models for four kinds of channel turbidites at different scales.The models integrate the turbidite depositional site,accommodation space geometry,internal turbidite characteristics,and the rock,log,and seismic facies obtained through drilling.Furthermore,guided by the principle of facies-controlled reservoir distribution,new composite elastic parameters were constructed based on an improved ray-path elastic impedance inversion method.These parameters provided enhanced resolution for turbidite sandstone reservoirs,enabling a quantitative prediction of such reservoirs.Validation with post-test wells demonstrates high accuracy and favorable application outcomes.Overall,this study serves as a foundational guide for oil and gas resource assessments and well placement in similar deep-water areas.

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Quantitative analysis of seismic velocity model accuracy and its influence on migration imaging: A case study of ultradeep fault-controlled fractured-vuggy reservoirs in the Tarim Basin,China
LIU Zhi-Yuan, LIU Xi-Wu, YANG Wei, ZHANG Qing, XIAO Yan-Jun
Geophysical and Geochemical Exploration. 2025, 49 (4): 925-932.   DOI: 10.11720/wtyht.2025.0026
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Seismic velocity model accuracy significantly influences the quality of depth-migrated images.However,a quantitative analysis and clear understanding of this relationship remain lacking.Based on the seismic images of ultradeep fault-controlled fractured-vuggy reservoirs in the Tarim Basin,this study constructed a depth-domain numerical velocity model that approximates the conditions of subsurface media.The 3D seismic forward modeling was performed using a seismic acquisition and observation system for practical production.Different interval velocities within the numerical model were smoothed and used to quantitatively analyze their effects on reverse time migration(RTM) images based on identical parameters.Using seismic simulation data as input,the isotropic and anisotropic depth-domain velocity models were constructed following a standard industrial workflow.A quantitative analysis was subsequently conducted to analyze the differences of the constructed models and corresponding migration images from the numerical velocity model and its RTM image across different intervals and for various geological features.Overall,this study quantitatively analyzes the velocity accuracy of different velocity types in various intervals and its influence on migration imaging, obtaining several clear insights.

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Geochemical assessment and spatial distribution characteristics of the environmental quality of topsoils in Fujian Province
WANG Wen-Jun
Geophysical and Geochemical Exploration. 2025, 49 (4): 933-942.   DOI: 10.11720/wtyht.2025.1372
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Based on the high-precision and high-quality data of eight heavy metals obtained from the 1∶250,000 multi-purpose regional geochemical survey in Fujian Province, this study investigated the topsoils (depths: 0~20 cm) throughout the province, with reference to the Environmental Quality Standard for Soils (GB 15618—2018). A geochemical assessment method for soil environmental quality based on individual/composite indices, matching the structural characteristics of the assessment standard, was developed to first assess the environmental quality of topsoils across Fujian Province. The results indicate that the topsoils in Fujian Province are dominated by strongly acidic and acidic soils, representing 36.5% and 57.89% of the total area in the province, respectively. The soils for prioritized conservation cover 91.06% of the total area, suggesting overall high soil environmental quality in the province. The over-limit ratio of 8.94% for soil heavy metals in the province is significantly below the total over-limit ratio of 16.1% in China. The element with the highest over-limit ratio is Pb, accounting for 4.95%, followed by Cd, accounting for 2.84%. In contrast, elements like Zn, Hg, Cu, As, Ni, and Cr show minimal over-limit ratios. Regarding the spatial distribution characteristics of topsoil elements, zones with over-limit Pb, Cd, Zn, Cu, As, and Cr are primarily distributed in the metal or non-metal sulfide deposits/ore occurrences/mineralized spots within the Wuyishan metallogenic belt and their surrounding areas. Zones with over-limit Hg are primarily distributed in the junction zone between Youxi and Dehua counties, as well as in cities along the coastal area of Fujian Province. The zone with over-limit Ni is predominantly located in the geological background area of the Fotan Formation basalts and olivine basalts in the northeast of Zhangpu County. Overall, the soil environmental quality is higher in the coastal area compared to the inland area. The assessment results of this study fill the gap in the geochemical assessment of soil environmental quality in Fujian Province, first providing the comprehensive geochemical assessment data of soil environmental quality for the province. These data, revealing the environmental quality of soil resources in Fujian Province, serve as fundamental geochemical data for scientific research in related fields and for constructing the geological information engineering big data platform for Fujian Province. Overall, this study provides a decision-making reference for soil environment management, territorial space planning, and the construction of the national ecological civilization pilot zone (Fujian) in Fujian Province, holding significant scientific value.

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Geochemical characteristics and health risk assessment of heavy metals in soil-crop systems
WANG Zhi-Qiang, NI Ping, ZHANG Hong-Xu, SHI Tian-Chi, YANG Jian-Feng, ZHANG Hui-Ling
Geophysical and Geochemical Exploration. 2025, 49 (4): 943-953.   DOI: 10.11720/wtyht.2025.1455
Abstract   HTML ( 0 )   PDF (1470KB)

This study analyzed the distributions, enrichment characteristics, and health risks of heavy metals (Cd, Cr, Hg, As, and Pb) in soil-crop (maize, rice, and wheat) systems in the Shizuishan area, Ningxia Hui Autonomous Region. The results indicate that the contents of heavy metals in the soils were below national background values, with the geoaccumulation index indicating an overall clean soil environment. Different crops showed significant differences in their ability to enrich heavy metals, with Cd and Pb being more enriched in wheat, and As and Hg being more enriched in rice. Moreover, significant correlations were observed between soil pH and heavy metal enrichment coefficients. With an increase in pH value, maize exhibited markedly increased enrichment coefficients for Cr and As, whereas rice manifested a notably decreased enrichment coefficient for As. Soil organic matter inhibited the ability of crops to absorb and enrich heavy metals by reducing the bioavailability of heavy metals. The health risk assessment reveals a high non-carcinogenic risk index for children via the hand-to-mouth route. The As content in some samples exceeded the limit specified in food safety standards, requiring targeted monitoring. The results of this study provide a scientific basis for soil contamination control and safe crop production.

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Contamination characteristics and risk assessment of soil heavy metals in a typical industrial town in Shandong Province, China
ZENG Jiao, KONG Ling-Hao, LIU Shu-Liang, CHU Hong-Xian, ZHAO Zheng-Peng, YANG Kai-Li, GUO Xu-Jun, CHEN Liang
Geophysical and Geochemical Exploration. 2025, 49 (4): 954-964.   DOI: 10.11720/wtyht.2025.1275
Abstract   HTML ( 0 )   PDF (2434KB)

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.

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Selenium background values and their responses to soil factors along the northern margin of the Tibetan Plateau
MA Qiang, QIANG Xiao-Nong, WU Jin-Hong, DAI Lu, HE Lian-Zhen, WANG Shuai, MA Nan
Geophysical and Geochemical Exploration. 2025, 49 (4): 965-972.   DOI: 10.11720/wtyht.2025.1189
Abstract   HTML ( 0 )   PDF (3857KB)

This study aims to determine the selenium (Se) background values of oils along the northern margin of the Qinghai-Tibet Plateau and serve the utilization of Se-rich resources, as well as the prevention and control of Se deficiency risks. To this end, this study systematically collected 8 273 surface soil samples and 2 190 deep soil samples, analyzed and tested the Se content and other relevant indicators, and examined the response relationships between soil Se and factors such as soil type and physicochemical properties. The results indicate that the surface and deep soils exhibit Se background values of 0.188×10-6 and 0.153×10-6, respectively. High Se background values are identified in the Menyuan Basin, the Xining Basin, the northern part of Qinghai Lake, and the Lagrange and Daban mountains. The highest Se background values occur in soils with the weathering materials of red and coal-bearing clastics of the Paleogene Xining Group as parent materials. The Se background values exhibit a negative correlation with pH and a positive correlation with the contents of organic matter and iron-aluminum oxides. Se in soils tends to accumulate in woodlands, grasslands, peat-rich marsh soils, and meadow soils. The study posits that the soil-forming parent materials with Se background values, including red and coal-bearing clastics of the Paleogene Xining Group, serve as the primary factor controlling the formation of Se-rich soils, and the secondary controlling factors include carbon-rich forests, grasslands, meadow soils, and marsh soils. The transportation by water streams and sedimentary transformation of these controlling factors contribute to the formation of the spatial distribution pattern of localized Se enrichment in the soils of the northern margin of the Qinghai-Tibet Plateau.

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Discussion on the delimitation, exploitation, and utilization of arid saline lacustrine sedimentary type selenium-rich land: A case study of the Hongshuiquan area, Qinghai Province
MA Qiang, MIAO Guo-Wen, ZHU Ming-Xia, WANG Shuai, HE Lian-Zhen, MA Nan
Geophysical and Geochemical Exploration. 2025, 49 (4): 973-979.   DOI: 10.11720/wtyht.2025.1320
Abstract   HTML ( 0 )   PDF (1643KB)

Based on the summary of the genetic types and elemental characteristics of national selenium (Se)-rich land, this study explored the arid saline lacustrine sedimentary type Se-rich land. According to the requirements for the delimitation and identification of natural Se-rich land, this study assessed and delimited the Se content, environmental quality, and fertility of soils in Hongshuiquan Township, Ping'an District, Haidong City, Qinghai Province. The results indicate that the soils in the Hongshuiquan area are alkaline, exhibiting a high background level of available Se. Specifically, the content of soil Se ranged from 0.037 mg/kg to 6.544 mg/kg, with an average of 0.352 mg/kg. The contents of Cd, Hg, Pb, and Cr in the soils did not exceed their contamination risk screening values for agricultural land. Additionally, soil As shows potential risk in local plots. In terms of fertility status, the soils exhibit abundant available phosphorus and potassium, and moderate nitrogen and organic matter. Based on the above results and the designated values for Se-rich land in the alkaline soil area, while excluding soil contamination risk zones and considering the continuity, scale, and development and utilization of plots, this study delimited 43 591 mu (1 mu=0.066 7 hectares) of natural green Se-rich land in the Hongshuiquan area, including 13 513 mu for direct agricultural use, and 30 078 mu for potentially utilizable forest land and grassland. Considering local conditions, this study suggests the development of the integrated agriculture and animal husbandry industry in the Hongshuiquan area, centering on the delimited zones and extending to the peripheries with moderate Se content. Planting grain crops and green forage grass in the delimited zones, surrounded by free-range grazing, forming an industrial layout of land with high Se content for grain crops and land with moderate Se content for grazing. Overall, this study holds critical reference significance for further exploring Se-rich land resources in Qinghai Province, scientifically planning the selenium industry, highlighting location advantages, and efficiently transforming resource value.

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Three-dimensional numerical simulations of spectral induced polarization for detecting landfill leachate
SHI Jing, XIONG Bin, XU Zhi-Feng, HUANG Li-Shan, LU Yu-Guo, LI Yao-Xin, YU Jia-Min
Geophysical and Geochemical Exploration. 2025, 49 (4): 980-988.   DOI: 10.11720/wtyht.2025.1384
Abstract   HTML ( 2 )   PDF (5250KB)

The contamination of soils and groundwater caused by landfill leachate is increasingly prominent. Given the distinctive electrical properties of leachate, such as low resistivity, high polarization, high time constant, and low-frequency correlation coefficient, this study performed three-dimensional finite element numerical simulations of landfills using the spectral induced polarization (SIP) method. The aim is to explore the theoretical effects of this method in detecting landfill leachate. First, this study conducted forward modeling for typical geoelectric models using the algorithm developed in this study. The result revealed a maximum relative error between the numerical and analytical solutions of less than 2.5%, demonstrating the algorithm's accuracy and effectiveness. Second, the parameters of the SIP model were set based on the actual electrical characteristics of landfills, ensuring that the numerical simulations closely reflected actual conditions. Finally, SIP anomaly responses were compared and analyzed for landfill leachate leakage under different scenarios. The results indicate that the leachate locations can be accurately delineated using the apparent complex resistivity's phase and apparent dispersion, regardless of whether landfills are equipped with high-resistivity impermeable walls. For leachate plumes of the same scale, shallower locations corresponded to more pronounced anomaly morphologies of apparent complex resistivity's phase and apparent dispersion. Compared to the direct current resistivity method, the SIP method can detect richer underground electrical parameters, achieving better application effects in detecting landfill leachate.

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AN ANALYSIS OF THE SPECIAL WAVE IMPACT ON THE INTERPRETATIONOF THE COALFIELD COLLAPSE COLUMN
YANG Xiao-Dong, YANG De-Xi
Geophysical and Geochemical Exploration    2010, 34 (5): 627-631.  
Abstract2726)      PDF (4180KB)(4972)      


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.

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The application of integrated geological, geochemical and geophysical techniques to the exploration of the Bogutu gold deposit
YAO Tie, ZHOU Yong, DU Zhan-Jun, ZHAO Zhen-Ming
Geophysical and Geochemical Exploration    2015, 39 (5): 877-884.   DOI: 10.11720/wtyht.2015.5.01
Abstract1464)   HTML151)    PDF (12833KB)(4378)      

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.

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Review on the study of grounded-source transient electromagnetic method
ZHANG Ying-Ying
Geophysical and Geochemical Exploration    2021, 45 (4): 809-823.   DOI: 10.11720/wtyht.2021.1513
Abstract1327)   HTML653)    PDF (729KB)(4266)      

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.

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The application of integrated geophysical prospecting methods to the exploration of urban buried fault
LIU Wei, HUANG Tao, WANG Ting-Yong, LIU Yi, ZHANG Ji, LIU Wen-Tao, ZHANG Qi-Bin, LI Qiang
Geophysical and Geochemical Exploration    2021, 45 (4): 1077-1087.   DOI: 10.11720/wtyht.2021.1525
Abstract972)   HTML408)    PDF (4078KB)(4113)      

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.

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A NEW DEVELOPMENT PERIOD OF THE GRAVITY AND MAGNETIC EXPLORATION
ZHANG Chang-Da, DONG Hao-Bin
Geophysical and Geochemical Exploration    2010, 34 (1): 1-7.  
Abstract3456)      PDF (431KB)(3729)      

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.

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THE ADVANCES IN THE STUDY OF THE AIRBORNE GRAVIMETRY SYSTEM
WANG Jing-Bo, XIONG Sheng-Qing, ZHOU Xi-Hua, GUO Zhi-Hong
Geophysical and Geochemical Exploration    2009, 33 (4): 368-373.  
Abstract3017)      PDF (1014KB)(3611)      

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.

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THE PROGRESS AND PROSPECT OF THE ELECTRICAL RESISTIVITY IMAGING SURVEY
YAN Jia-yong, MENG Gui-xiang, LV Qing-tian, ZHANG Kun, CHEN Xiang-bin
Geophysical and Geochemical Exploration    2012, 36 (4): 576-584.   DOI: 10.11720/wtyht.2012.4.13
Abstract5234)      PDF (1427KB)(3505)      
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.
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THE UTILIZATION OF EXCEL TO THE PERFORMANCE OF R-MODE CLUSTER ANALYSIS
CHUN Nei-ya
Geophysical and Geochemical Exploration    2007, 31 (4): 374-376.  
Abstract4742)      PDF (659KB)(3202)      

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.

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3D DISPLAY FOR GROUND PENETRATING RADAR BASED ON Matlab
WU Bao-Jie, JI Mei-Xiu, YANG Hua
Geophysical and Geochemical Exploration    2009, 33 (3): 342-344.  
Abstract6885)      PDF (532KB)(3186)      

 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.

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RECENT ADVANCES IN THE RESEARCH AND DEVELOPMENT OF QUANTUM MAGNETOMETERS
ZHANG Chang-da
Geophysical and Geochemical Exploration    2005, 29 (4): 283-287.  
Abstract1819)      PDF (376KB)(2996)      

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

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CHEMICAL COMPOSITIONS OF CONTINENTAL CRUST AND ROCKS IN EASTERN CHINA
Yan Mingcai, Chi Qinghua, Gu Tiexin, Wang Chunshu
Geophysical and Geochemical Exploration    1997, 21 (6): 451-459.  
Abstract3140)      PDF (2969KB)(2911)      

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.

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THE APPLICATION OF ATOM INTERFEROMETER TO THE MEASUREMENT OF GRAVITATIONAL ACCELERATION
ZHANG Chang-da
Geophysical and Geochemical Exploration    2000, 24 (5): 321-326.  
Abstract1811)      PDF (673KB)(2871)      

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.

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THE PRESENT SITUATION AND RESEARCH ADVANCES OF EXPLORATION GEOCHEMISTRY FOR PORPHYRY COPPER DEPOSITS
HU Shu-qi, MA Sheng-ming, LIU Chong-min
Geophysical and Geochemical Exploration    2011, 35 (4): 431-437.  
Abstract3840)      PDF (643KB)(2853)      

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.

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CALCULATION OF THE ANOMALY AREA
Zhao Rongjun
Geophysical and Geochemical Exploration    2000, 24 (2): 154-156.  
Abstract1641)      PDF (346KB)(2843)      

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.

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THE CHOICE OF GRIDDING METHODS FOR GEOPHYSICAL DATA
LIU Zhao-Ping, YANG Jin, WU Wei
Geophysical and Geochemical Exploration    2010, 34 (1): 93-97.  
Abstract3236)      PDF (1939KB)(2827)      

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.

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THE EXTRACTION METHOD AND PROGRAM DESIGN FOR DISPERSION CURVE IN F-K DOMAIN
LI Jie, CHEN Xuan-hua, ZHANG Jiao-dong, ZHOU Qi, LIU Gang, LIU Zhi-qiang, XU Yan, LI Bing, YANG Jing
Geophysical and Geochemical Exploration    2011, 35 (5): 684-688.  
Abstract3826)      PDF (534KB)(2717)      

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.

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A TENTATIVE DISCUSSION ON THE RESOLUTION OF THE GROUND-PENETRATING RADAR
YUAN Ming-de
Geophysical and Geochemical Exploration    2003, 27 (1): 28-32.  
Abstract2594)      PDF (512KB)(2638)      

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.

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THE APPLICATION OF THE GRADIENT SOUNDING PROFILE METHOD TO THE GOLD PROSPECTING IN THE YINAN GOLD MINE
DU Li-ming, WU Jun-jie, YANG Jin-duo, WANG Peng, YU Bao-xian
Geophysical and Geochemical Exploration    2013, 37 (2): 225-228.   DOI: 10.11720/j.issn.1000-8918.2013.2.07
Abstract2448)      PDF (964KB)(2614)      
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.
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THE APPLICATION OF NEW GEOCHEMICAL EXPLORATION METHODSTO MINERAL EXPLORATION AND ITS GEOLOGICAL EFFECT
JIANG Yong-Jian, WEI Jun-Hao, ZHOU Jing-Ren, WANG Zhong-Ming, JI Zhao-Jia, WANG Fa-Yan
Geophysical and Geochemical Exploration    2010, 34 (2): 134-138.  
Abstract4365)      PDF (403KB)(2584)      

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.

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Characteristics of gravity and magnetic fields in Ordos Basin and their geological significance
Bing LI, Yan-Bing SONG, Lei SHI, Qi WANG, Jiu-Ming JIANG, Jiu-Qiang JIN, De-Wen ZHOU, Ming XU, Gang-Yi XIAO, Min-Ying XIE
Geophysical and Geochemical Exploration    2019, 43 (4): 767-777.   DOI: 10.11720/wtyht.2019.1391
Abstract809)   HTML3)    PDF (3147KB)(2422)      

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.

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Geophysical and Geochemical Exploration    1982, 6 (3): 154-156.  
Abstract1235)      PDF (190KB)(2397)      
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THE AUTOMATIC FORMATION OF THE SUFFER SOFTWARECONTOUR LEVEL FILE BASED ON AREA STATISTICS
REN Lei, CHEN Hua-Gen
Geophysical and Geochemical Exploration    2009, 33 (5): 595-598.  
Abstract3709)      PDF (830KB)(2363)      

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.

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WAVE FIELD SEPARATION NUMERICAL MODELING OF SECOND ORDER ELASTIC WAVE EQUATION BY HIGH-PRECISIONSTAGGEREDGRID FINITE DIFFERENCE SCHEME
CHEN Ke-Yang, YANG Wei, LIU Hong-Lin, WU Qing-Ling
Geophysical and Geochemical Exploration    2009, 33 (6): 700-703.  
Abstract3233)      PDF (1060KB)(2355)      

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.

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THE DISTRIBUTION AND LEVEL OF RADON GAS IN SOIL IN A HIGH RADIATION BACKGROUND CITY OF CHINA
WANG Nan-ping, XIAO Lei, LI Can-ping
Geophysical and Geochemical Exploration    2012, 36 (4): 646-650.   DOI: 10.11720/wtyht.2012.4.27
Abstract3927)      PDF (726KB)(2355)      
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.
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THE APPLICATION OF THE POST-OPERATION DIFFERENCE TECHNIQUE TO IMPROVE THE LOCATING PRECISION OF THE HAND-HELD GPS
GAO Jian-dong, LEI Yu-wen
Geophysical and Geochemical Exploration    2006, 30 (5): 446-449.  
Abstract2122)      PDF (359KB)(2336)      

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.

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ABUNDANCE OF CHEMICAL ELEMENTS OF SOILS IN CHINA AND SUPERGENESIS GEOCHEMISTRY CHARACTERISTICS
Yan Mingcai, Gu Tiexin, Chi Qinghua, Wang Chunshu
Geophysical and Geochemical Exploration    1997, 21 (3): 161-167.  
Abstract2727)      PDF (2180KB)(2330)      

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.

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PARAMETER SELECTION IN VIBROSEIS SEISMIC EXPLORATION
XUE Hai-Fei, DONG Shou-Hua, TAO Wen-Peng
Geophysical and Geochemical Exploration    2010, 34 (2): 185-190.  
Abstract3556)      PDF (3477KB)(2326)      

 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.

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RESEARCH AND APPLICATION ON NUMERICAL INTEGRATIONOF HANKEL TRANSFORMS BY DIGITAL FILTERING
ZHANG Wei, WANG Xu-Ben, QIN Qing-Yan
Geophysical and Geochemical Exploration    2010, 34 (6): 753-755.  
Abstract3787)      PDF (363KB)(2317)      

 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.

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SOME PROBLEMS CONCERNING THE CONVERSIONOF MAPS BETWEEN SURFER AND MAPGIS
QIN Lin-Jiang
Geophysical and Geochemical Exploration    2010, 34 (5): 677-680.  
Abstract5572)      PDF (865KB)(2304)      

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.

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THE UTILIZATION OF SURFER TO CONDUCT THE DRAWING OF PROFILE-PLAN
SUN Zhong-ren, ZHAO Dong-liang
Geophysical and Geochemical Exploration    2006, 30 (2): 172-174.  
Abstract3657)      PDF (572KB)(2297)      

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.

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A GENERALIZED DESCRIPTION OF THE DEVELOPMENT OF ELECTRIC EXPLORATION METHODS
Li Jinming
Geophysical and Geochemical Exploration    1996, 20 (4): 250-258,249.  
Abstract3938)      PDF (659KB)(2291)      

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.

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FEATURES OF GEOPHYSICAL COMPOSITE ANOMALIES AND ORE RESOURCES IN YIHUANG AREA, JIANGXI PROVINCE
WANG Wei-Beng, FANG Ying-Yao, TUN Cheng-Beng
Geophysical and Geochemical Exploration    2010, 34 (5): 573-578.  
Abstract3146)      PDF (2717KB)(2262)      

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.

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MIGRATION VELOCITY ANALYSIS AND MIGRATION IMAGING RESEARCH
YE Jing-Yan, YAO YA-Lin, WANG Yan-Qun, LI Qing
Geophysical and Geochemical Exploration    2009, 33 (6): 674-677.  
Abstract2910)      PDF (1927KB)(2227)      

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.

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THE CALCULATION METHOD OF EQUIVALENT DIELECTRIC CONSTANT OF MULTI-LAYER UNDERGROUND MEDIA
XIAO Min, CHEN Chang-yan, SU Zhao-feng, JIA Hui, ZHANG Hui
Geophysical and Geochemical Exploration    2013, 37 (2): 368-372.   DOI: 10.11720/j.issn.1000-8918.2013.2.37
Abstract4305)      PDF (780KB)(2219)      
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.
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PRESENT STATE AND REVIVAL OF GRAVITY GRADIOMETRY
Zeng Hualin
Geophysical and Geochemical Exploration    1999, 23 (1): 1-6.  
Abstract2303)      PDF (474KB)(2212)      

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.

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PRESENT RESEARCH SITUTATION AND DEVELOPMENT TREND OF AIRBORNE GRAVITY GRADIOMETER
SHU Qing, ZHOU Jian-xin, YIN Hang
Geophysical and Geochemical Exploration    2007, 31 (6): 485-488.  
Abstract2281)      PDF (690KB)(2190)      

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.

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THE INVERSED PROBLEM IN GRAVITY AND MAGNETICEXPLORATION: A REVIEW
Zeng Hualin
Geophysical and Geochemical Exploration    1990, 14 (3): 182-190.  
Abstract2108)      PDF (737KB)(2181)      

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.

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CHAMP, GRACE AND GOCE: THREE SATELLITES FOR SENSING AND/OR MEASURING THE EARTH'S GRAVITY FIELD
ZHANG Chang-da
Geophysical and Geochemical Exploration    2005, 29 (5): 377-382.  
Abstract2186)      PDF (749KB)(2118)      

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.

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SOME BASIC PROBLEMS IN THE APPLICATION OF GROUND-PENETRATION RADAR
Lei Linyuan
Geophysical and Geochemical Exploration    1998, 22 (6): 408-414.  
Abstract2379)      PDF (1144KB)(2106)      

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.

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THE APPLICATION OF SEISMIC REFRACTION WAVE METHOD ANDHIGHDENSITY RESISTIVITY METHOD TO TUNNEL INVESTIGATION
ZENG Guo, CUI De-Hai, LIU Jie, LI Kai
Geophysical and Geochemical Exploration    2009, 33 (5): 608-612.  
Abstract3281)      PDF (1351KB)(2099)      

 Basic principles and techniques for the shallow seismic refraction wave method and the highdensity resistivity method

are described in this paper in combination with engineering practice to explain the results of the refraction wave method and the

high-density resistivity method in railroad and highway tunnel exploration. The application effects of the combination of these two

methods in detecting positions, sizes, natures and characteristics of such harmful geological bodies as concealed faults and shatter

zones are also discussed. Some measures for improving the investigation accuracy of these two methods are put forward.

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New progress in the technology and applications of SOTEM
XUE Guo-Qiang
Geophysical and Geochemical Exploration    2024, 48 (5): 1165-1168.   DOI: 10.11720/wtyht.2024.0325
Abstract549)   HTML11)    PDF (380KB)(554)      

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

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Stocks and content of organic and inorganic carbon in soil of the Loess Plateau region
DUAN Xing-Xing, LIU Xiao-Long, HAN Bao-Hua, Adilai·Saitiniyazi , JIN Meng-Ting, LIU Tong
Geophysical and Geochemical Exploration    2025, 49 (1): 239-247.   DOI: 10.11720/wtyht.2025.3603
Abstract333)   HTML2)    PDF (4635KB)(132)      

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.

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Analysis of critical parameters in the field acquisition of short-offset transient electromagnetic data
CHEN Wei-Ying, XUE Guo-Qiang, LI Hai
Geophysical and Geochemical Exploration    2024, 48 (5): 1169-1175.   DOI: 10.11720/wtyht.2024.1197
Abstract315)   HTML6)    PDF (2409KB)(340)      

The grounded-source short-offset transient electromagnetic (SOTEM) method involves many parameters in field data acquisition. The selection of these parameters is closely associated with the signal quality and detection sensitivity of measured data. Based on the relevant provisions in the organization standard, Technical specification for grounded-source short-offset transient electromagnetic method (T/CGS 002—2021), issued by the Chinese Geophysical Society, numerical emulations, and practical cases, this study analyzed and expounded the selection criteria of critical parameters like transmitting source length, transmitting fundamental frequency, offset, device type, and observation component. The insights obtained in this study are significant for guiding the field construction of the SOTEM device and leveraging its detection performance.

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Stratigraphic architecture and activity of the alluvial fan in the eastern piedmont of the Liupan Mountains since the Late Pleistocene
YAO Zi-Heng, DONG Xiao-Peng, YANG Yong
Geophysical and Geochemical Exploration    2025, 49 (1): 1-13.   DOI: 10.11720/wtyht.2025.2257
Abstract254)   HTML7)    PDF (11949KB)(158)      

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.

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Organic carbon content-baesd prediction and influencing factors of black soil layer thicknesses
LIU Kai, DAI Hui-Min, LIU Guo-Dong, LIANG Shuai, WEI Ming-Hui, YANG Ze, SONG Yun-Hong
Geophysical and Geochemical Exploration    2024, 48 (5): 1368-1376.   DOI: 10.11720/wtyht.2024.1436
Abstract247)   HTML6)    PDF (4274KB)(271)      

Black soil layer thicknesses, anessential attribute of black soil,serves as a significant indicator for measuring the fertility and erosion degree of black soil. Their spatial prediction holds critical significance for supporting China's black land conservation and ensuring food security.Considering the diagnostic characteristics of black soil layers in soil system classification, this study regarded soil layers with organic carbon content higher than 6×10-3 of soil parent materials as black soil layers.Moreover, it derived the calculation formula for the thicknesses of black soil layers relying on the exponential distribution pattern of organic carbon in the vertical soil profile. Based on the 62 896 topsoil and 15 687 deepsoil organic carbon data obtained from the multi-purpose regional geochemical survey, this study conducted detailed spatial prediction of the thicknesses of black soil layers in the Songliao Plain and analyzed their relationship with soil types and climate factors. Key findings are as follows:(1) The thicknesses of black soil layers in the Songliao Plain range from 0 to 165 cm, with a median of 23.33 cm;(2) The spatial distribution of black soil layers exhibits significant heterogeneity, characterized by thin southwestern and thick northeastern portions;(3) The black soil layers of swampy soil and peat soil manifest the largest average thicknesses between 60 and 80 cm, followed by those of typical black soil (average thickness: 56 cm) and those of albic soil and meadow soil (average thickness: 40~50 cm);(4) The spatial distributions of the thicknesses of black soil layers are closely associated with climatic conditions, primarily showing a significant negative correlation with temperature and a positive correlation with rainfall;(5) The mean annual temperature of 0 ℃ is a significant temperature threshold for the development of thick black soil layers.Above this temperature, the average thickness of black soil layers exceeds 80 cm and no longer changes with temperature. With global warming, the southward shift of this 0 ℃ is otherm may significantly influence the thicknesses of black soil layers.

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Application of wide-field electromagnetic sounding method to deep prospecting in the Mangling ore concentration area in North Qinling: A case study of the Yaozhuang ore district
ZHANG Xiao-Tuan, LI Xin-Lin, ZHOU Bin, GAO Wei-Qiang
Geophysical and Geochemical Exploration    2024, 48 (6): 1609-1617.   DOI: 10.11720/wtyht.2024.0056
Abstract237)   HTML3)    PDF (6000KB)(271)      

The Mangling ore concentration area with intense magmatic activity has become a focal area for deep prospecting in the North Qinling tectonic belt in recent years. The formation of molybdenum deposits in this area is closely related to small Late Jurassic acidic intrusions. To achieve breakthroughs in deep ore prospection within this area, this study conducted the wide-field electromagnetic sounding over the concealed Yaozhuang intrusion delineated based on gravity anomalies. The results indicate the presence of pronounced high-resistivity anomalies at depth, and it is inferred that the protruding part of the anomalies corresponds to the concealed Yaozhuang intrusion. The resistivity inversion results roughly delineated the variations in the top surface of the intrusion, with the elevations and N-S width of the top surface estimated at -300~620 m and 1300~1600 m, respectively. Drilling in the most favorable deep mineralized part confirmed the presence of the concealed intrusion and concealed molybdenum ore bodies. The results of this study demonstrate that the wide-field electromagnetic sounding method exhibits great sounding depths and high resolutions, serving as an effective method for deep ore prospecting in the Mangling ore concentration area.

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Development of a nodal rotational seismometer with a micro-electro-mechanical system sensor and testing of H/V spectral ratios
JIA Song, HE Zhan-Xiang, YANG Hui, YAO Yong-Chao, WANG Cai-Xia
Geophysical and Geochemical Exploration    2024, 48 (6): 1471-1478.   DOI: 10.11720/wtyht.2024.0140
Abstract224)   HTML4)    PDF (3283KB)(221)      

In response to the increasing demand for large-scale field seismic acquisition, this study developed a low-cost multifunctional nodal rotational seismometer (RBWL) with a micro-electro-mechanical system (MEMS) sensor, considering the functionality, economic feasibility, and the ease of arrangement. The RBWL employs a low-cost and low-power MEMS sensor to acquire seismic signals, involving three-component translational motions (Tx,Ty,Tz) and three-component rotational motions (Rx,Ry,Rz). To reduce the impacts of environmental factors on measurements, the system of the RBWL automatically records real-time information including temperature and attitude while performing compensation correction on the measurement results. For real-time monitoring and data transmission at acquisition nodes, the system establishes a data transmission link integrating 4G, cloud, and client, with the measured maximum data transmission rate up to 100 Mbps. The testing of H/V spectral ratios verifies the system functions and principal performance parameters of the RBWL and its effectiveness in engineering physical exploration.

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Metallogenic prediction based on the deep interest evolution network: A case study of supergenetic calcrete-hosted uranium deposits in Western Australia
ZHANG Chang-Jiang, HE Jian-Feng, NIE Feng-Jun, XIA Fei, LI Wei-Dong, WANG Xue-Yuan, ZHANG Xin, ZHONG Guo-Yun
Geophysical and Geochemical Exploration    2025, 49 (2): 259-269.   DOI: 10.11720/wtyht.2025.1391
Abstract222)   HTML12)    PDF (9933KB)(168)      

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.

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Total rare-earth oxides in stream sediments in the Dechang area: Geochemical characteristics and prospecting targets
ZHU You-Huan, NIE Fei, ZOU Jia-Zuo, LI Hong-Wei, ZHOU Xue-Cheng, RAN Guang-Hui, LEI Dong
Geophysical and Geochemical Exploration    2025, 49 (2): 270-280.   DOI: 10.11720/wtyht.2025.2571
Abstract209)   HTML18)    PDF (4186KB)(117)      

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.

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Application of the opposing coils transient electromagnetic method in a shallow groundwater-rich area: A case study of Xiacun Town, Xinyu City
ZHU Xiao-Wei, DING Chen, XUE Kai-Xi, CHEN Jun, HAN Kai-Min, LUO Qiang, YI Guang-Sheng
Geophysical and Geochemical Exploration    2024, 48 (5): 1424-1436.   DOI: 10.11720/wtyht.2024.1574
Abstract203)   HTML4)    PDF (7265KB)(326)      

Unfavorable geobodies such as Karsts, weak soil, and water-rich areas are extensively distributed in China. Under heavy rainfall, they are prone to geologic hazards like collapse. A severe geological collapse occurred in Xiacun Town, Yushui District, Xinyu City, near the Shanghai-Kunming high-speed railway. The space around the collapsed foundation pit was limited, with many interference sources like underground pipelines. With early signals subjected to the mutual inductance effects of receiver and transmitter coils, the conventional transient electromagnetic method exhibited low detection accuracy and anti-interference ability, encountering significant shallow blind zones. To locate unfavorable geobodies in the study area and provide suggestions for the prevention and control of geologic hazards, this study innovatively applied the opposing-coils transient electromagnetic method (OCTEM), supplemented by borehole-based verification. The results show that: (1) The OCTEM exhibited high accuracy, as demonstrated by the high consistency between the geophysical exploration results and the drilling results of the study area; (2) The low-resistivity zone spread across the study area, and the low-resistivity anomalies revealed by geophysical exploration were caused by groundwater according to borehole-based verification; (3) The strata from top to bottom were composed of soft plastic silty clay, hard plastic silty clay, soft plastic silty clay, and moderately weathered limestones; (4) The subsurface micro-confined water in the collapse area surged upward, gradually eroding the soft plastic silty clay layer around the area. The static water level in the collapsed foundation pit manifested an elevation of 55.60 m, located approximately 1.4 m below the surface; (5) A groundwater channel existed under the collapse area, with soil caves formed in the limestone layer under the prolonged erosion effect of water flow; (6) Long-term groundwater extraction may expand the underground seepage zone; (7) The administrative department in charge must promptly contain groundwater in the collapse area to prevent it from further eroding the surrounding unconsolidated soil layer.

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Geochemical characteristics and formation mechanism of thermal spring water in the Chuhe fault zone in Anhui Province
WANG Guo-Jian, HU Wen-Hui, LI Guang-Zhi, ZHU Huai-Ping, HU Bin, XIAO Peng-Fei, ZHANG Ying
Geophysical and Geochemical Exploration    2024, 48 (5): 1223-1231.   DOI: 10.11720/wtyht.2024.1145
Abstract191)   HTML5)    PDF (3297KB)(225)      

Several thermal springs associated with tectonic activity occur along the Chuhe fault zone. Except for the Bantang thermal spring at the southern end, other springs along the fault zone exhibit unideal utilization of thermal energy. This affects the development of local industries. Therefore, it is necessary to delve into the geochemical characteristics and formation mechanism of typical thermal springs along the Chuhe fault zone. The purpose is to provide scientific evidence for the rational utilization and exploration methods of geothermal resources in the thermal spring groups in the future. Therefore, this study investigated thermal springs in the Bantang, Zhaoguan, and Xiangquan areas along the Chuhe fault zone, where nine samples of thermal spring water, cold well water, and surface water were collected individually. For these samples, the composition tests of 25 indices, including anions, cations, and major and trace elements, were tested, and the hydrogen and oxygen isotope values were determined. The analyses of the 25 measured indices, along with the investigation of the geothermal water source and controlling factors through hydrogen and oxygen isotope tracing, indicate that the thermal spring water in the three areas tends to be of the CaSO4 type and is all closely related to the interactions between groundwater and surrounding rocks. The thermal spring water, cold well water, and surface water in Bantang and Zhaoguan show consanguinity, with geothermal water being directly recharged with local precipitation and surface water. In contrast, the thermal spring water, surface water, and cold well water in the Xiangquan area show weaker consanguinity, indicating different sources for the underground cold water runoff and geothermal water. This should be noted when determining the primary factors controlling the thermal spring in this area. The temperatures calculated using a chalcedony geothermometer were close to the temperatures of the hot water recovered on the surface. In contrast, the temperatures calculated using a quartz geothermometer approached the temperatures of deep geothermal reservoirs. The results of this study preliminarily reveal the geochemical characteristics, recharge relationships, and water-rock interactions of thermal spring water in the Chuhe fault zone and propose effective geochemical geothermometers for the study area. These contribute to deeper insights into the mechanisms and controlling factors of the thermal springs along the fault zone, as well as providing practical value and a methodological model for enhancing thermal spring functionality and geothermal resource exploitation and utilization in the future.

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Factors influencing the application of ESPAC-based microtremor survey in shallow surface environments
YANG Lang-Yong-Hang, LI Hong-Xing
Geophysical and Geochemical Exploration    2024, 48 (5): 1322-1330.   DOI: 10.11720/wtyht.2024.1479
Abstract184)   HTML5)    PDF (5302KB)(371)      

The extended spatial autocorrelation (ESPAC)-based microtremor exploration(natural-source surface wave exploration) technology has been extensively used in shallow formation exploration owing to its simplicity,efficiency,and accuracy.However,the imaging effect of dispersion energy extracted based on the ESPAC method is unsatisfactory in practical applications.In particular,different observation array arrangements influence the extraction of dispersion curves from collected data.By investigating the imaging principle of the ESPAC method,this study conducted the simulation experiment of natural-source microtremor recording through ambient noise simulation.It compared the differences in dispersion energy under various dominant frequency distributions of wavelets.Moreover,it quantitatively analyzed the influence of different station arrangements and acquisition durations on the imaging quality of dispersion energy.The comparative study reveals the imaging patterns of the ESPAC method in shallow surface exploration.The ESPAC method can maximize the imaging quality of dispersion energy in the fundamental mode while considering both efficiency and exploration costs.The results of this study were applied to engineering application cases to further verify the simulation results.

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A log-based lithofacies identification method based on random forest and sedimentary microfacies characteristics:A case study of tight sandstones in the second member of the Xujiahe Formation in the Xinchang area
HE Xiao-Long, ZHANG Bing, YANG Kai, HE Yi-Fan, LI Zhuo
Geophysical and Geochemical Exploration    2024, 48 (5): 1337-1347.   DOI: 10.11720/wtyht.2024.0180
Abstract173)   HTML0)    PDF (5425KB)(204)      

Tight sandstones serve as significant oil and gas reservoirs.Their lithofacies identification can assist in further understanding the developmental characteristics of reservoirs.Combining core observations with log data processing,this study analyzed the lithofacies and sedimentary microfacies characteristics of tight sandstones in the Xinchang area and the internal relationships between lithofacies and sedimentary microfacies.Moreover,it constructed a random forest classification model with geological implications through data mining of sedimentary microfacies characteristics.The results show that:(1)Tight sandstones in the Xinchang area can be classified into seven typical lithofacies,including mudstone,siltstone with ripple lamination,massive fine sandstone,fine sandstone with parallel bedding,massive medium- to coarse-grained sandstone,and medium- to coarse-grained sandstone with parallel/cross bedding;(2)The sedimentary microfacies in the Xinchang area consist primarily of subaqueous distributary channel,subaqueous distributary bay,river-mouth bar,and prodeltaic mud,which are closely associated with the sedimentation of lithofacies;(3)In the classification model,the relative centroid(RM),root mean square deviation(GS),average median(AM),and average slope(M) of the gamma ray(GR) curve can be used as the characteristic parameters of sedimentary microfacies to increase the number of characteristics in the dataset;(4)Considering the characteristics of sedimentary microfacies,especially the energy and turbulence of water bodies,can significantly enhance the performance of the random forest classification model.Overall,the results of this study provide a novel approach for lithofacies identification using machine learning methods and a significant reference for oil and gas exploration in tight sandstones.

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Response of the geochemical anomalies of cobalt to ore-bearing geological bodies in the Mangyahedong area, eastern Kunlun
MA Wen-Jun, XIE Hai-Lin, GUO Wei, LI Fei-Fei, TENG Xiao-Yan, CHEN Su-Liong, LI Shao-Nan, LIU Xiu-Feng, MA Zhong-Ying, MA Hai-Yun
Geophysical and Geochemical Exploration    2024, 48 (5): 1232-1246.   DOI: 10.11720/wtyht.2024.0031
Abstract172)   HTML5)    PDF (14076KB)(250)      

Over recent years, large-scale geochemical surveys on a scale of 1:25,000 have been conducted in the eastern Kunlun region for geological prospecting. These surveys, characterized by the rapid and accurate location of anomaly sources, have been widely applied in mineral explorations, yielding encouraging mineral prospecting results. Using 1:25,000-scale stream sediment surveys, this study delineated 12 geochemical integrated anomalies of the element associations of Cu, Co, and Ni in the Hedong area, Mangya City, eastern Kunlun. These anomalies include one integrated anomaly dominated by Co, where various element anomalies exhibit high-degree overlap, relatively large scales, high intensity, and distinct concentration zoning. The Co anomaly is closely associated with the Ordovician Qimantag Group, demonstrating a high degree of spatial consistency. The subsequent anomaly verification reveals four cobalt mineralized zones within anomalies GA16, GA26, GA11, and GA39, with three ore bodies and multiple mineralized bodies of cobalt being identified within the mineralized zones. The comprehensive analysis indicates that the eastern Kunlun region enjoys excellent metallogenic geological conditions and favorable geochemical characteristics, with promising prospecting results having been achieved. Therefore, this region has the prospecting potential of medium to large-scale cobalt deposits.

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2D/3D electrical exploration based on borrowing-line telecontrol electrode arrays
GE Wei-Zhong, LIANG Bing-He, GAO Jian-Dong, Lv Yu-Zeng, CHEN Long
Geophysical and Geochemical Exploration    2024, 48 (6): 1437-1447.   DOI: 10.11720/wtyht.2024.0170
Abstract172)   HTML13)    PDF (3061KB)(314)      

The telecontrol electrode array is a new type of electrode array for power supply and observations that utilizes the carrier waves of the power-supply and measurement wires used in conventional electrical prospecting to transmit signals. By remotely controlling a series of coded electrode switches between various wires and their connections, this array allows for orderly power supply and measurements. This array enables flexible spacings between electrodes and the gradual expansion of the distances between power supply electrodes via remote control, thus achieving a gradient-based sounding array. The borrowing-line remote controller can be used combined with single-channel, multi-channel, and high-density resistivity instruments, and the combined arrays can perform 2D/3D electrical prospecting more effectively. Followed by the brief introduction of the principle of the borrowed-line telecontrol electrode array, this study discusses the applications and examples of this array and several combined arrays in the resistivity method and induced polarization (IP).

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Definition, classification, and functions of underground research laboratories for the geological disposal of high-level radioactive waste and the scientific research plan of Beishan underground research laboratory
WANG Ju, LUN Long
Geophysical and Geochemical Exploration    2024, 48 (6): 1507-1518.   DOI: 10.11720/wtyht.2024.1556
Abstract170)   HTML3)    PDF (8255KB)(162)      

Underground research laboratories (URLs) for the geological disposal of high-level radioactive waste serve as critical facilities for verifying the safety and suitability of the sites of potential disposal repositories and for developing disposal technologies. URLs are irreplaceable in many aspects such as the siting and system design of potential disposal repositories, the development of the theories and technologies for disposal engineering, the safety and characteristic assessments, full-scale field tests, and on-site demonstration. This study highlights the definition, classification, and functions of URLs and categorizes existing primary URLs both in China and abroad. URLs are generally categorized into general URLs (first generation) and site-specific URLs (second generation). The construction of disposal repositories in China has progressed from national, regional, and site screening to site evaluation and to URL construction. The authors of this study proposed the concepts of "site-specific URLs" and "third-generation URLs" in 2010 and 2014, respectively. Furthermore, the Beishan URL-the world's first site-specific URL for the geological disposal of high-level radioactive waste-has been built. This study introduces the siting process, planning, positioning, and functions of the Beishan URL, as well as the functions of primary scientific experiments and main field experiments conducted during its construction. The results of this study serve as a guide for future siting and R&D of disposal repositories.

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A fault extraction technique based on structure-oriented filtering and its application
YAO Ming
Geophysical and Geochemical Exploration    2024, 48 (5): 1313-1321.   DOI: 10.11720/wtyht.2024.1418
Abstract168)   HTML5)    PDF (7103KB)(218)      

Accurately identifying faults is crucial for the exploration and exploitation of oil and gas fields,and further fault extraction based on this holds critical significance for later comprehensive research.At present,the commonly used fault extraction techniques primarily include automatic fault tracking,fault slice interpretation,and manual interpretation.However,these fault extraction techniques and their application in practical exploration and exploitation often face the following challenges.Automatic fault tracking based on an attribute volume often extracts faults with low accuracy and poor continuity,whereas fault slice interpretation and conventional manual interpretation require long work cycles.Hence,this study proposed a fault extraction technique based on structure-oriented filtering.First,the original poststack seismic data were processed through structure-oriented filtering to improve the quality of fundamental data and enhance the fault boundary features.Then,a relative isochronous model was established based on the filtered data volume,with sensitive attributes that can characterize faults extracted.Finally,based on the analysis of fault combination relationships,a comprehensive interpretation method combining plane and profile views was employed to extract faults.The technique proposed in this study has been successfully applied to a certain block of SB.As indicated by the application results,the proposed technique exhibits higher reliability,accuracy,and efficiency compared to the three commonly used fault extraction techniques, thus demonstrating high applicability.

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Development and sea trials of a marine towed geomagnetic vector measurement system
LUO Jian-Gang, LI Hai-Hu, LIU Jing-Xiao, LI Hai-Bing, GUO Zi-Wei, SUN Ning, FU Bi-Bo, ZHANG Feng, LI Xue-Yan
Geophysical and Geochemical Exploration    2024, 48 (6): 1455-1462.   DOI: 10.11720/wtyht.2024.0155
Abstract166)   HTML6)    PDF (3254KB)(215)      

The geomagnetic field is a vector field in space. However, traditional marine magnetic surveys focus on geomagnetic field intensity, failing to fully acquire and utilize rich information about the geomagnetic vector field. Given this, this study developed a towed marine geomagnetic vector measurement system. This system was designed to operate in dynamic marine conditions and ultimately acquire geomagnetic vector field data within the geographical coordinate system. Through sea trials of the system, grid line and repeat line measurements were obtained. After preprocessing the collected data, the measurement accuracy of repeat lines and crosspoints was better than 6.7 nT and 6 nT, respectively. The results of the sea test indicate that the measurement system has the preliminary ability to measure the geomagnetic vector field at sea, and it can be applied to geomagnetic field measurement tasks near or far sea, obtaining richer geomagnetic field information.

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Application of time-frequency peak filtering with minimum mean cross-entropy in ground penetrating radar signal denoising
ZHENG Wei, TIAN Ren-Fei, GAO Yu-Han, WU Bin
Geophysical and Geochemical Exploration    2025, 49 (2): 404-410.   DOI: 10.11720/wtyht.2025.1300
Abstract165)   HTML3)    PDF (4113KB)(70)      

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.

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Microtremor survey-based investigation of deep geothermal- and water-controlling structures in the Salt Lake geothermal field, Yuncheng City, Shanxi Province, China
WANG He-Yu, WU Guo-Peng, CHEN Guo-Xiong, CHAI Jian-Zhou, MAO Jie, WANG De-Tao
Geophysical and Geochemical Exploration    2025, 49 (1): 32-40.   DOI: 10.11720/wtyht.2025.1327
Abstract162)   HTML5)    PDF (4299KB)(206)      

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.

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An automatic fitting method for a variogram based on deep learning
ZHAO Li-Fang, YU Si-Yu, LI Shao-Hua
Geophysical and Geochemical Exploration    2024, 48 (5): 1359-1367.   DOI: 10.11720/wtyht.2024.1522
Abstract158)   HTML0)    PDF (3408KB)(203)      

A variogram serves as a crucial tool for quantifying spatial correlations. However, existing variogram fitting methods often yield unstable results. This study proposed an automatic variogram fitting method based on deep learning, aiming to enhance the precision and stability of automatic fitting. The fitting of the experimental variogram is essentially a nonlinear optimization problem, which involves optimizing the matching between the experimental and theoretical variograms. The proposed method generated substantial training datasets using several sets of theoretical variograms with varying parameter values for training and learning in deep neural networks. The trained model was then used for the automatic fitting of the experimental variogram. Multiple sets of experimental results demonstrate that based on the robust fitting capability of deep neural networks, the proposed method manifested superior fitting stability and computational efficiency compared to the least squares method, providing a novel approach for automatic variogram fitting in geostatistics.

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Application cases of the short-offset transient electromagnetic method in detecting goafs with thick overburden in a coal mine
HUANG Shi-Mao, YANG Guang, WANG Jun-Cheng, LUO Chuan-Gen, XU Ming-Zuan, ZHOU Nan-Nan, ZHAO Peng
Geophysical and Geochemical Exploration    2024, 48 (5): 1208-1214.   DOI: 10.11720/wtyht.2024.1232
Abstract158)   HTML2)    PDF (4749KB)(286)      

Within a coal mine in Peixian County, Xuzhou City, brick-red Paleogene and Neogene strata were deposited in the faulted basin during the Cenozoic, with extensive Quaternary strata overlying various strata. The Quaternary, Jurassic, and Cretaceous strata exhibit thick overburden, up to over 500 m. This study explored the coal mine using the short-offset transient electromagnetic (SOTEM) method. Based on geoelectric conditions, reasonable observation parameters were designed to obtain the subterranean electric structure within a burial depth of 1500 m. Goafs were detected at a burial depth of 900 m, with their delineated boundaries aligning with the mining situation of the coal mine. The results of this study serve as a reference for detecting goafs with thick overburden in North China-type coalfields.

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Three-dimensional numerical simulation of short-offset transient electromagnetic responses to water-rich bodies in coal mines
CHANG Jiang-Hao, XUE Jun-Jie, MENG Qing-Xin, ZHAO Peng
Geophysical and Geochemical Exploration    2024, 48 (5): 1176-1184.   DOI: 10.11720/wtyht.2024.1300
Abstract157)   HTML4)    PDF (7711KB)(236)      

This study performed forward modeling for the short-offset transient electromagnetic (SOTEM) responses of a three-dimensional geoelectric model using the three-dimensional finite-difference time-domain method. The results reveal that: (1) The attenuation curves of the Ex responses from the electric field above the goaf or collapse column were above the background response curve at early times but below it at later times; (2) A shorter offset corresponded to a higher relative anomaly of ∂Bz/∂t response signals. Increasing the length of the transmitting source could enhance the signal intensity while slightly decreasing the relative anomaly; (3) In the case of survey lines close to the transmitting source, the overall ∂Bz/∂t responses of the goaf or collapse column were weaker than the background responses. For survey lines away from the transmitting source, the overall ∂Bz/∂t responses of the goaf or collapse column were stronger than the background responses. In summary, the calculation results demonstrate significant implications for understanding the ability of the SOTEM method to detect typical water-rich bodies in coal mines, laying a theoretical foundation for the parameter selection of SOTEM devices and their generalized application in the coal sector.

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Application of microtremor survey technology in shield tunnels passing through urban karst formations
ZHANG Zhong, FENG Wen-Cheng, LIN Yang
Geophysical and Geochemical Exploration    2025, 49 (2): 520-528.   DOI: 10.11720/wtyht.2025.1146
Abstract157)   HTML5)    PDF (7289KB)(183)      

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.

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Exploration and play fairway prediction of the Jinchanshan mine in Inner Mongolia using electro-adsorption method
CHEN Qing-Yun, ZHANG Jiang-Bo, ZHONG Song-Shu, ZHOU Qi-Ming, SHI Yu-Jiao, LIU Yao-Hui, ZHAO Li-Ke, TAN Jie
Geophysical and Geochemical Exploration    2025, 49 (2): 281-287.   DOI: 10.11720/wtyht.2025.2494
Abstract156)   HTML9)    PDF (4491KB)(95)      

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.

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Application of ground-penetrating radar in detecting the internal structures of the ancient Great Wall in Linhai City
YANG Hao, ZOU Jie, CHENG Dan-Dan, YU Jing-Lan
Geophysical and Geochemical Exploration    2024, 48 (6): 1741-1746.   DOI: 10.11720/wtyht.2024.0091
Abstract154)   HTML1)    PDF (3789KB)(236)      

Non-destructive testing of the internal structural characteristics of ancient buildings is the key to preserving cultural relics.To determine the structures and internal defects of the ancient Great Wall in Linhai City,this study performed non-destructive testing of the wall structures in different orientations using a ground-penetrating radar (GPR) combining 100 MHz and 270 MHz antennas.The testing results show significant structural stratification in the ancient Great Wall.The GPR signal-reflected images reveal clear internal wall defects like pores,cracks,voids,and other hidden dangers.This study demonstrates the reliability of the GPR in detecting structures and defects of ancient walls,there by providing technical support for the structural protection of the ancient Great Wall.

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Deriving analytical solution of the pseudo wavefield from transient electromagnetic data
LI Hai, ZHAO Pan, LI Ke-Ying, LIU Zheng
Geophysical and Geochemical Exploration    2024, 48 (5): 1193-1198.   DOI: 10.11720/wtyht.2024.1188
Abstract151)   HTML2)    PDF (1705KB)(254)      

The transform from transient electromagnetic (TEM) field to pseudo wavefield is the basis for using the imaging technique. The TEM field follows the diffusion equation, while the pseudo wavefield follows the wave equation. These two can be transformed into each other via the Q-transform. As the integral transformation from TEM field to pseudo wavefield is ill-posed, numerical method is used to get the desired pseudo wavefield. As a result, it is often the case that the methods and parameters are need to be optimized to get a optimal pseudo wavefield. Therefore, here in this paper, we derived the analytical solution of the pseudo wavefield from the TEM field. We start from the analytical formula of TEM field, and utilize the Laplace transform to establish the analytical solution pairs. The pairs can be used to test the accuracy and stability of the numerical method, as well as examining the features of the pseudo wavefield to get an effective imaging method.

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The indicators of tectonic superimposed halo for prediction and discrimination of denudation degree of deep and peripheral blind ore deposits of hydrothermal deposits and their application effect
WEI Zi-Xin, LI Hui, WEI Yang, REN Liang-Liang, WEI Jiang, WANG Xu, YU Bin, WANG Jun, PENG Wei, WANG Xi-Jun, XIE Zi-Chen, JIA Jin-Dian, YAO Yue-Wen, AN Na
Geophysical and Geochemical Exploration    2025, 49 (1): 14-21.   DOI: 10.11720/wtyht.2025.2580
Abstract150)   HTML2)    PDF (3456KB)(199)      

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.

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Development and application of a quality monitoring platform for nodal seismic data acquisition
ZHANG Jian
Geophysical and Geochemical Exploration    2025, 49 (2): 451-461.   DOI: 10.11720/wtyht.2025.1107
Abstract150)   HTML4)    PDF (12776KB)(94)      

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.

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Portable opposing-coils transient electromagnetic system and its application tests
ZHOU Sheng, CHEN Xing-Peng, WANG Jun, QI Qing-Xin, ZHANG Zhi-Qing, PAN Ji-Min, XI Zhen-Zhu, YANG Chun-Hua
Geophysical and Geochemical Exploration    2024, 48 (6): 1479-1485.   DOI: 10.11720/wtyht.2024.0169
Abstract148)   HTML5)    PDF (4415KB)(237)      

In shallow engineering investigations, the small-loop transient electromagnetic (TEM) system is challenged by limitations such as overweight equipment, significant transmitter-receiver mutual inductance, and high manpower requirements. Hence, this study introduced an improved system. Based on the opposing-coils transient electromagnetic (OCTEM) theory, this study calculated the magnetic field distribution of the generalized opposing-coils antenna device. Furthermore, it designed and developed efficient portable antennas and the supporting system (collectively referred to as the portable OCTEM system). Subsequent field experiments demonstrate that while ensuring exploration accuracy, the portable OCTEM system can enhance the investigation efficiency by effectively mitigating the transmitter-receiver mutual inductance and significantly reducing manpower requirements. This study preliminarily verifies the feasibility of the portable OCTEM system, providing a novel technology route for developing downsized shallow exploration equipment.

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Active/passive source-based observation experiments and applications of fiber-optic rotational seismometers
CAO Yu-Jia, CHEN Yan-Jun, LI Zheng-Bin, TENG Yun-Tian, ZHANG Ding-Fan
Geophysical and Geochemical Exploration    2024, 48 (6): 1486-1497.   DOI: 10.11720/wtyht.2024.0142
Abstract146)   HTML3)    PDF (9597KB)(235)      

In the past two decades, high-sensitivity ring laser gyroscopes have demonstrated the potential of rotational observation data in global seismology. Commercial fiber-optic three-component rotational seismometers have heralded a new development phase of rotational seismography. Field experiments for high-sensitivity portable fiber-optic rotational seismometers in China remain in the initial stage, whereas their relevant data analysis results have been obtained internationally. This study elucidated the co-located observation experiments on six components (6C, including three components of translational motions and three components of rotational motions) of an active source and a natural earthquake, involving experimental schemes, implementation steps, and subsequent data analysis. Moreover, this study revealed the primary factors influencing the experiment results by comparatively analyzing the similarities and differences of experiments. Fiber-optic rotational and conventional seismometers need to be fixed on the same rigid panel to ensure the consistency of received signals. Besides, proper ground coupling and burial processing contribute to high-quality experimental data. The experimental results indicate that water bodies will affect surface wave manifestation and P-wave clarity. These findings, enriching the practical experience in seismic rotational observation experiments, serve as a reference for the design of subsequent rotational observation experiments, thereby assisting in completing the experiments and obtaining higher-quality data. In terms of data application, this study optimized and substantiated the feasibility of the preprocessing scheme, with the backazimuth calculation accuracy improved by 58.8° and 50° at the two active-source measuring points, and by 24.1° and 29.4° at the two passive-source measuring points. The application of six-component seismic data from a single seismic station suggests that additional observation of rotational components can acquire more seismic wavefield information, thus the observation of rotational components can be employed to enhance the utilization of China's massive seismic observation data. Overall, fiber-optic rotational seismometers broaden the boundary of seismic monitoring technology, boost seismology research, and create new possibilities for future earthquake research.

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A Marchenko theory-based method for internal multiple suppression
LIAO Zhen, MA Ji-Tao, CHEN Xiao-Hong, LI Wen-Jin
Geophysical and Geochemical Exploration    2025, 49 (1): 52-62.   DOI: 10.11720/wtyht.2025.1213
Abstract145)   HTML2)    PDF (5190KB)(128)      

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.

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Prediction of heterogeneous,thin Triassic sandstone reservoirs in the Lunnan area,Tarim Basin
MI Xin-Wu, ZHOU Cheng-Gang, TIAN Jun, HAN Yao-Zu, LI Ya-Nan, XIAO Bing-Qing
Geophysical and Geochemical Exploration    2025, 49 (2): 321-329.   DOI: 10.11720/wtyht.2025.1357
Abstract145)   HTML16)    PDF (13788KB)(101)      

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.

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Application of three-dimensional magnetic anomaly inversion in magnetite exploration
ZHAO Bai-Ru, LI Hou-Pu, ZHANG Heng-Lei
Geophysical and Geochemical Exploration    2024, 48 (6): 1626-1632.   DOI: 10.11720/wtyht.2024.0167
Abstract142)   HTML3)    PDF (3579KB)(267)      

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

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Electrical structure characteristics and geothermal exploration directions of the upper crust on the eastern margin of the Yinchuan Basin
WU Yang, ZHAO Fu-Yuan, HU Xin-Jun, CHEN Xiao-Jing, BU Jin-Bing, GUO Shao-Peng
Geophysical and Geochemical Exploration    2024, 48 (5): 1258-1267.   DOI: 10.11720/wtyht.2024.1489
Abstract141)   HTML4)    PDF (8811KB)(252)      

The successful operation of geothermal wells on the eastern margin of the Yinchuan Basin suggests a new geothermal exploration orientation around the Huanghe fault and its secondary faults. To further investigate the controlling effect of the Huanghe fault on geothermal resources in the study area and pinpoint the exploration target, this study arranged four magnetotelluric (MT) lines, obtaining 71 survey points.The preprocessing and two-dimensional inversion of MT data yielded a two-dimensional electrical structure of the study area within a depth of 10 km.Based on the previous geological, gravity, microtremor, and controllable source audio magnetotellurics(CSAMT) data in the study area, this study further interpreted the strata and fault structures of the study area.It posited that the relatively-low-resistivity zone within the high-resistivity zone of the Ordovician basement reflected by the MT lines may be the secondary-fault development site at the rear edge of the Huanghe fault, which is caused by the fragmentation and water filling of Ordovician strata, showing certain exploration potential for geothermal resources.

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Application of factor analysis in geochemical zoning and its implications: A case study of 1:50,000 stream sediment survey in the Juxian-Wulian area, Shandong Province
LU Wen-Dong, SUN Bin, LI Guang-Jie, WEI Wei, XIA Xiao-Xing, PAN Bing-Lei, SHA Qing, LYU Xiao-Hong, LI Yuan-Chun, QIAO Na
Geophysical and Geochemical Exploration    2025, 49 (2): 411-421.   DOI: 10.11720/wtyht.2025.2505
Abstract140)   HTML3)    PDF (4697KB)(131)      

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.

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Marine controlled-source electromagnetics-based technology for generating arbitrary-frequency waveforms
WANG Jie, WANG Meng, REN Zhi-Bin, WANG Chen-Tao, WANG Hui-Min
Geophysical and Geochemical Exploration    2024, 48 (6): 1448-1454.   DOI: 10.11720/wtyht.2024.0165
Abstract137)   HTML5)    PDF (2713KB)(274)      

Marine controlled-source electromagnetics (MCSEM) is used to explore resources such as oil and gas hydrates, as well as deep geological structures, by revealing resistivity differences below the seabed. Different excitation frequencies correspond to varying detection depths. To enhance the resistivity imaging of targets beneath the seabed, this study investigated the MCSEM-based technology for generating arbitrary-frequency waveforms to flexibly alter the excitation frequency and improve the exploration effectiveness and efficiency. Using the direct digital frequency synthesis (DDS) chip AD9833 and the joint control of a microcontroller and a complex programmable logic device (CPLD), this study achieved the generation of arbitrary-frequency waveforms with limited precision. The test results indicate that this technology can effectively enhance the spectral adaptability and flexibility of MCSEM.

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Assessment of primary soil fertility indicators of different forest stand types in the Nanshan forest farm in Jiyuan City
WANG Yong-Feng, WANG Jian, PANG Guo-Tao, ZHU Wei-Ping, WANG Ke-Chao, WANG Xiao-En, WANG Zu-Zhen, LIU Jie
Geophysical and Geochemical Exploration    2024, 48 (5): 1400-1408.   DOI: 10.11720/wtyht.2024.1570
Abstract137)   HTML2)    PDF (2696KB)(275)      

Soil fertility is a significant indicator that measures the ability of soil to provide various nutrients required by vegetation and reflects the crop producing power of soil. To ascertain the soil fertility of different forest stand types in the Nanshan forest farm of Jiyuan City, this study investigated the soil of four forest stand types: Platycladus orientalis, Robinia pseudoacacia, Quercus variabilis, and walnut trees. It analyzed the soil nutrients of the forest stand types by determining the pH, organic matter, total nutrients (TN,TP,TK), and available nutrients (AN,AP,AK) of soil at different depths (0~40 cm). Moreover, it assessed the comprehensive soil fertility using the improved Nemerow comprehensive index method. The results show that: (1) Except pH, the physicochemical factors of the soil of the forest stand types in the study area exhibited moderate variations, and the soil TP, TK, AP, AK, and pH manifested significant differences; (2) With an increase in soil depth, the soil in the study area showed increased pH and bulk density, decreased organic matter, TN, and available nutrients, and almost unchanged TP and TK; (3) The assessment of soil nutrient abundance indicated that the TN, TP, and available nutrients were relatively poor in the soil of the study area; (4) Based on a comprehensive assessment, the soil fertility of four forest stand types at different depths decreased in the order of Robinia pseudoacacia, Quercus variabilis, Platycladus orientalis, and walnut trees. Their soil fertility was generally at an average level, with low values observed at depths ranging from 20 to 40 cm. The comprehensive analysis indicates that TN, TP, and available nutrients are deficient in the study area. Therefore, applying appropriate organic fertilizers, nitrogen, and phosphorus is recommended for the study area.

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Application of an improved SRME method in eliminating land surface multiples
QI Peng, YANG Jin-Long, HU Shou-Wang
Geophysical and Geochemical Exploration    2024, 48 (5): 1331-1336.   DOI: 10.11720/wtyht.2024.1271
Abstract136)   HTML4)    PDF (4565KB)(235)      

Surface-related multiple elimination(SRME) is vital in processing seismic data.At present,the SRME method most commonly used for processing marine data can effectively predict surface-related multiple models,achieving multiple elimination through matching and subtraction.However,this method requires full wave field information,thus placing higher demands on observation systems.The irregular land data acquisition makes it difficult to apply this method for processing land data.Hence,this study presented an improved SRME method,which performs moveout correction on adjacent channels for multiple prediction by constructing the minimum error constraint function,thus enhancing the adaptability to complex observation systems.The improved SRME method was applied to process the actual seismic data of land.Its effectiveness was validated by comparing the gathers,velocity spectra,prestack time migration profiles,and synthetic seismograms before and after SRME.

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Advances and performance of seismic exploration experiments in the western Yin'e Basin
WANG Xing-Yu, LIU Yan-Li, WANG Tong, RONG Li-Xin
Geophysical and Geochemical Exploration    2024, 48 (6): 1599-1608.   DOI: 10.11720/wtyht.2024.1507
Abstract134)   HTML4)    PDF (15587KB)(200)      

This study aims to improve the seismic exploration effects in the Upper Paleozoic strata of the Yin'e Basin.With the Juyanhai depression in the western Yin'e Basin as an experimental area,it investigated the previous seismic acquisition characteristics and current data processing techniques of the area.Through field seismic acquisition experiments and data processing research in the laboratory,it explored and summarized the seismic exploration techniques for the Upper Paleozoic strata in the Yin'e Basin.Key findings are as follows:(1)The combination of shot holes and seismic vibrators is recommended for seismic excitation in the area according to local conditions;(2)The receiving array length takes precedence over the receiving density;(3)Targeted processing techniques including anisotropy processing,spectral-constrained deconvolution,and wedge transform adaptive denoising can effectively improve the quality of deep seismic imaging.This study provides a reference for relevant research in similar areas.

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Seismic prediction of unfavorable geobodies in tunnels using the borehole-roadway transient electromagnetic method
LI He, LI Xiu, QI Zhi-Peng, CAO Hua-Ke
Geophysical and Geochemical Exploration    2024, 48 (5): 1215-1222.   DOI: 10.11720/wtyht.2024.1277
Abstract133)   HTML2)    PDF (8377KB)(270)      

Tunnel detection in complex environments requires fine-scale detection of small unfavorable geobodies like karst caves and fissures. Hence, this study designed a tunnel construction model with a small karst cave in front of the tunnel face. A borehole was drilled at the center point of the tunnel face towards the construction direction, and then an electrical source was put into the borehole for excitation. Array data acquisition was conducted on the tunnel face. The 3D forward modeling based on transient electromagnetic data was performed using the time-domain finite element method. As indicated by the results, the electromagnetic sounding of the target was achieved through the movement of the electrical source, and the planar position of the unfavorable geobody was determined based on the distribution patterns of the electromagnetic field on the tunnel face. Therefore, electrical source excitation in a borehole can enhance the detection ability of the transient electromagnetic method on small karst caves, serving as a feasible method for improving the accuracy of tunnel seismic prediction.

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Petrophysical modeling of tight sandstones of the Lianggaoshan Formation,Southeast Sichuan
ZHANG Zheng-Yu-Cheng, SU Jian-Long
Geophysical and Geochemical Exploration    2025, 49 (2): 288-298.   DOI: 10.11720/wtyht.2025.1356
Abstract132)   HTML4)    PDF (3907KB)(126)      

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.

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Investigating fault structure characteristics based on aeromagnetic data and precise relocation results of small earthquakes: A case study of the Panxi area
LI Jiao-Jiao, ZHANG Yong-Jun, HE Yi-Yuan, LI Yi-Chuan, LI Shi-Jun, CHEN Yao
Geophysical and Geochemical Exploration    2025, 49 (1): 206-214.   DOI: 10.11720/wtyht.2025.1082
Abstract126)   HTML2)    PDF (7402KB)(125)      

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.

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Development of a submarine optically pumped magnetometer
GONG Yi-Xuan, JIANG Kai, GAO Jing-Yu, ZHU Wan-Hua, CHEN Kai
Geophysical and Geochemical Exploration    2024, 48 (6): 1498-1506.   DOI: 10.11720/wtyht.2024.0144
Abstract125)   HTML4)    PDF (4010KB)(184)      

The Autonomous Underwater Vehicle (AUV) equipped with a magnetometer conducts underwater magnetic anomaly detection, enabling long-duration and large-scale continuous sampling. It offers advantages such as concealment, high efficiency, high practicality, wide application range, strong maneuverability, and robust endurance. To improve measurement accuracy, synchronous seabed magnetic field data is needed as a reference to counteract environmental magnetic noise. To address this, a submarine optically pumped magnetometer was developed to provide a reference for processing AUV magnetic anomaly detection data.The submarine optically pumped magnetometer consists of a magnetic field measurement unit and an acoustic release unit, capable of high-precision autonomous acquisition of the total magnetic field on the seabed, as well as underwater acoustic release and recovery. The magnetic field measurement unit includes an optical pumping probe, electronic unit, counter, battery pack, and nylon pressure chamber. The acoustic release unit includes an acoustic transducer, acoustic communication board, electro-corrosion decoupler, cement block, buoyancy block, and frame. This design addresses key technical challenges such as miniaturization, autonomous acquisition, and underwater acoustic communication.In 2022, a magnetic anomaly detection test was conducted in the offshore waters of Qingdao. The test results verified the autonomous seabed magnetic field acquisition and the release and recovery functions of the submarine optically pumped magnetometer, providing effective reference data for underwater target detection.

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A method for estimating electromagnetic wave velocities in subsurface media based on common-offset GPR signal envelope and 3D velocity spectrum analysis
ZHOU Xin, WANG Hong-Hua, WANG Yu-Cheng, WU Qi-Ming, WANG Hao-Lin, LIU Hong-Rui
Geophysical and Geochemical Exploration    2024, 48 (6): 1693-1701.   DOI: 10.11720/wtyht.2024.1526
Abstract124)   HTML1)    PDF (4846KB)(157)      

Currently,velocity spectrum analysis methods widely used for ground-penetrating radar(GPR) signals mostly construct velocity spectra by superposing the amplitude energy of coherent signals to estimate electromagnetic wave velocities in subsurface media.In the case of multiple peaks and troughs in signal wavelets,velocity spectra constructed using these amplitude-based methods display multiple energy clusters,adversely affecting the identification,picking,and velocity estimation of subsequent energy peaks.Hence,this study proposed a method for estimating electromagnetic wave velocities in subsurface media based on common-offset GPR signal envelope and 3D velocity spectrum analysis.By scanning the signal envelope of hyperbolic diffracted waves in the GPR profile,the proposed method constructed the 3D velocity spectra of superimposed energy varying with zero-offset two-way travel time,test velocity,and measuring point position.Moreover,it extracted the slices of 2D velocity spectra according to the positions of hyperbolic vertices in the 3D velocity spectra.On this basis,the test velocities corresponding to the energy peaks in the slices of 2D velocity spectra were picked as the electromagnetic wave velocities in subsurface media.The numerical test results show that compared to the amplitude-based methods,the signal envelope-based 3D velocity spectrum analysis method obtained velocity spectra characterized by fewer continuous energy clusters,more concentrated energy,and minor velocity estimation errors,thus more effectively constructing the velocity model with inverse-time migration.

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Application of the unmanned aerial vehicle-airborne gamma-ray spectrometry system to follow-up geochemical surveys in high-relief areas
ZHONG Hui-Rong, YANG Cheng-Zhi, YANG Qing-Hua, XIN Chao, YANG Lei, WANG Wei
Geophysical and Geochemical Exploration    2024, 48 (5): 1268-1274.   DOI: 10.11720/wtyht.2024.1565
Abstract122)   HTML3)    PDF (3183KB)(252)      

In response to the need for large-scale exploration of radioactive minerals in high-relief areas, this study developed an airborne gamma-ray spectrometer based on small-sized NaI (Tl) crystals, which was integrated with the F-120 unmanned aerial vehicle (UAV) to form an airborne gamma-ray spectrometry (AGRS) system. The UAV-AGRS system was applied to the follow-up geochemical survey of uranium deposits in a certain area of South China. The survey results show roughly consistent locations and morphologies for high-anomaly zones with the ground gamma-ray spectrometry results. Moreover, the results of this study exhibit more detailed anomaly morphologies, and more significant responses of uranium content-related uranium channel data to known uranium occurrences in the study area, suggesting superior data. Therefore, the UAV-AGRS system shows promising potential as an effective alternative to ground gamma-ray spectrometry for the follow-up geochemical survey of uranium deposits in high-relief areas.

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AMT-based geological-geophysical prospecting model for the gold ore zone in the Daduhe area, Shimian County, Sichuan Province
YAO Wen, GUO Jun, SUN Chong-Bo, ZHOU Hong-Bing, ZHANG Hong-Chao
Geophysical and Geochemical Exploration    2024, 48 (5): 1247-1257.   DOI: 10.11720/wtyht.2024.1545
Abstract121)   HTML2)    PDF (8840KB)(338)      

The gold ore zone in the Daduhe area of Shimian County, Sichuan Province, is located in the rare metal-precious metal-nonferrous polymetal metallogenic belt in the southern segment of the Songpan-Ganzi orogenic belt. It exhibits complex structures and steep terrains, severely restricting prospecting and exploration. Based on the geological settings, conditions, and geophysical characteristics for regional mineralization, this study investigated the typical Luoluoping gold deposit in Shimian by conducting deep geophysical exploration centered on audio-frequency magnetotellurics (AMT). Three low-resistivity anomalies (M1, M2, and M3) were identified, corresponding to the mineralized alteration zone I, the gold mineralization zone III, and the gold-copper ore body, respectively, demonstrating the effectiveness and applicability of geophysical methods for deep prospecting. Combined with geological understanding and engineering verification, this study summarized geological and geophysical prospecting markers for the typical gold deposit, establishing the geological-geophysical prospecting model for the gold ore zone in the study area. Therefore, this study provides technical support for deep prospecting in the study area.

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Distribution of macroelements in surface sediments and their geological implications from Qinzhou Bay, Guangxi
WANG Zhi-Jun, WANG Jian, WANG Ke-Chao, LIU Jian, WANG Yong-Feng, SUN Zhong-Yu
Geophysical and Geochemical Exploration    2024, 48 (5): 1377-1387.   DOI: 10.11720/wtyht.2024.0034
Abstract120)   HTML0)    PDF (6429KB)(190)      

This study examined 121 sets of surface sediments collected from Qinzhou Bay, Guangxi, China, determining their grain sizes and macroelement contents and analyzing the characteristics, spatial distribution patterns, and sources of microelement assemblages. The results indicate the presence of eight types of surface sediments in Qinzhou Bay, which are dominated by sands and silty sands in terms of grain size. The surface sediments featured a stable macroelement composition,with SiO2, Al2O3, Fe2O3, and CaO accounting for about 95.54% of the total sediments. Of these, SiO2 and Al2O3 exhibited the highest contents, averaging 73.23% and 8.71%, respectively. Compared to the upper continental crust (UCC), these surface sediments are enriched in SiO2, MnO, and TiO2 but depleted in other elements. These sediments displayed similar spatial distribution patterns of Al2O3, MgO, TiO2, K2O, and Na2O. The significant positive correlations between these oxides indicate similar factors governing their distributions. Using Al as a reference,the enrichment factors (EFs) of nine macroelements in the study area were calculated. The results indicate that these elements largely originated from the UCC, with those from some sites being potentially affected by other factors. A comprehensive analysis of correlation and R factors shows that the ten types of macroelements in the study area can be divided into three categories. The first category consists of SiO2, Al2O3, Fe2O3, MgO, MnO, TiO2, K2O, and Na2O, suggesting a source of terrigenous clastic sediments. The second category is CaO, principally representinga marine biological source. The third type comprises P2O5, representinga mariculture source. The analysis of these sediment sources using the PCA-MLR model reveals that the three sources exhibit relative contribution rates of 46.14%, 15%, and 38.86%, respectively.

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Design and application of the dynamic management system for scientific data of the Beishan underground research laboratory
MA Ming-Qing, CHEN Liang, WANG Ju, LI Xiao-Jun, ZHANG Zhi-Wei, LING Hui
Geophysical and Geochemical Exploration    2024, 48 (6): 1559-1567.   DOI: 10.11720/wtyht.2024.0017
Abstract119)   HTML2)    PDF (4462KB)(145)      

The construction of the Beishan underground research laboratory (URL) is a key initiative under China's 13th Five-Year Plan. During the construction and operation of the URL, extensive scientific data will be generated in field experiments. To ensure the integrity, reliability, authenticity, and traceability of these data and to ensure that researchers can manage and utilize various types of data in an efficient and convenient manner, it is necessary to develop a dynamic management system tailored for the scientific data of the URL. The purpose is to provide data support and a decision-making basis for the R&D of disposal engineering technologies and safety assessments. This study introduces the background and overall requirements for the development of the scientific data dynamic management system for the Beishan URL, proposes a general design scheme, and provides a comprehensive overview of the system's functional architecture and content. The system is primarily composed of modules for system management, system status management, basic data management, metadata management, experimental information management, experimental data management, data quality management, and data visualization. This system has been preliminarily applied to the management of field experimental processes and data for the Beishan URL, yielding encouraging results.

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Impacts of drone noise on semi-airborne transient electromagnetic data
WANG Zhi-Hong, ZHANG Nuo-Ya, HU Shan-Shan, ZHENG Zi-Qiang, LIU Yu-Chao, ZHOU Zheng, SUN Huai-Feng
Geophysical and Geochemical Exploration    2024, 48 (6): 1633-1642.   DOI: 10.11720/wtyht.2024.1544
Abstract118)   HTML1)    PDF (4475KB)(182)      

As a semi-airbone transient electromagnetic (TEM) platform, drones inherently generate electromagnetic signals that may interfere with the collected transient electromagnetic data. This study investigated the impacts of drone noise on the collected data. Through outdoor experiments and systematic performance testing, this study analyzed the impacts of drone noise under varying rotor speeds, suspension lengths, flight height, and flight speeds. Accordingly, this study proposed methods for suppressing drone noise, such as determining the optimal suspension length and incorporating shielding layers. The study was conducted using the KWT-X8L-25 octocopter drones, but the research methodology and philosophy are also applicable to other drone models, thus serving as a reference for the selection of semi-airborne TEM platforms.

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