E-mail Alert Rss
 
Quick Search
Highlights
More>>
Current Issue Just Accepted Archive Most Download Most Read
  20 June 2024, Volume 48 Issue 3 Previous Issue   
For Selected: View Abstracts Toggle Thumbnails
Research and application of the log-based comprehensive identification method for low-contrast oil layers:A case study of the Lufeng oilfield in the Pearl River Mouth Basin
LIU Wei-Nan, GUAN Yao, LIU Dao-Li, SHI Lei, SONG Wei
Geophysical and Geochemical Exploration. 2024, 48 (3): 573-583.   DOI: 10.11720/wtyht.2024.1164
Abstract   HTML ( 11 )   PDF (7267KB)

The accurate identification of fluid properties is critical for reservoir evaluation.However,for the Paleogene low-porosity and low-permeability reservoirs in the Lufeng area,Pearl River Mouth Basin,the low contrast between oil and water layers in conventional logs due to the presence of high-resistivity water layers complicates the identification of oil and water layers.This study first ascertained the reservoir characteristics and genetic analysis of low-contrast oil layers.Then,it developed the Flair gas logging response equation and the Flair logging response correction method,aiming to overcome the challenge that gas logging response values of low-porosity and low-permeability reservoirs are significantly influenced by factors such as drilling rate and porosity.Given the differences in the properties and components of various fluids,this study constructed new oil-bearing and water-content indices using Flair gas logging curves.Moreover,this study characterized the geochemical chromatogram using a gamma probability distribution function and extracted the shape and scale factors to describe the chromatogram characteristics.Based on sensitivity parameters,this study plotted the characteristic parameter-based fluid property identification chart.The practical application shows that the log-based comprehensive fluid property identification method can yield satisfactory effects,achieving a compliance rate of 91.3%.Therefore,this method can be popularized.

Figures and Tables | References | Related Articles | Metrics
Petrogenesis and rubidium enrichment indication of the Fuling rock mass in southern Anhui Province
ZHANG Jun, TAO Nai, QI Shang-Xing, WANG Zhi-Qiang, DA Hao-Xiang
Geophysical and Geochemical Exploration. 2024, 48 (3): 584-596.   DOI: 10.11720/wtyht.2024.1268
Abstract   HTML ( 3 )   PDF (7620KB)

The Fuling rock mass in southern Anhui Province, located in the eastern section of the Jiangnan uplift zone, is a complex granitic rock mass that has experienced multi-stage evolution. It primarily comprises two lithologies: Monzogranite and K-feldspar granite. By investigating the geological, petrographic, and petrogeochemical characteristics of the Fuling rock mass, this study delved into its evolutionary characteristics, genetic types, and tectonic environment, aiming to clarify its indication significance for rubidium enrichment. The results of this study are as follows: ① The geochemical characteristics of the Fuling rock mass demonstrate high SiO2, Na2O, K2O, and Al2O3 contents, high w(K2O)/w(Na2O) ratios, and aluminum saturation indices (A/CNK) ranging from 0.95~1.08 (average: 0.99), suggesting high-K calc-alkaline quasi-aluminous to peraluminous granites; ② In terms of trace elements, the Fuling rock mass possesses high Li, Rb, Nd, and Ta contents and significantly low Sr and Ba contents, which may be associated with the fractional crystallization of feldspar; ③ The w(Nb)/w(Ta) ratios ranging from 5.71~10.94 (average: 8.41) and Mg# values ranging from 0.02~0.31 (average: 0.13) indicate that the Fuling rock mass was primarily derived from the partial melting of lower crust rocks, suggesting A-type granites in a non-orogenic extensional environment; ④ The Rb content in the Fuling rock mass increases with the magmatic evolution degree. Compared to monzogranites, K-feldspar granites with a higher evolution degree display higher Rb content, implying that the Rb content in the Fuling rock mass is generally controlled by magmatic evolution. Overall, this study holds some reference significance for understanding the Yanshanian diagenesis and mineralization of southern Anhui Province.

Figures and Tables | References | Related Articles | Metrics
Element geochemical characteristics of weathering crust profiles of the Wenchuan section in the upper arid valley of the Minjiang River
ZHOU Xue-Ni, CAO Ya-Ting, JI Yang
Geophysical and Geochemical Exploration. 2024, 48 (3): 597-608.   DOI: 10.11720/wtyht.2024.1255
Abstract   HTML ( 4 )   PDF (6076KB)

This study conducted geochemical tests and analyses for vertical rock-soil profiles with different bedrock types in the Wenchuan section in the upper arid valley of the Minjiang River. Based on the above, this study explored the vertical distributions of elements in these weathering crust profiles to investigate the influence of bedrocks on the contents of chemical elements in soils. From a geological perspective, this study provided proposals for planting in agricultural production and eco-environmental restoration for the study area. The results of this study are as follows: (1) From top to bottom, weathering crust profiles can be divided into four layers: the humus layer (A), the illuvial layer (B), the soil parent material layer (C), and the bedrock layer (R). The humus layers exhibit higher average values of Al, Ca, K, Mg, Fe, Se, Zn, Cu, Cd, and Pb and lower average values of Si, Na, Mn, Cr, As, Cd, and Hg, compared to corresponding national average values in soils; (2) In weathering crust profiles with different bedrock types, except for elements with higher contents in both bedrocks and corresponding soil layers, the same elements manifest similar contents in other soil layers; (3) The chemical weathering intensity increased from the bedrock to the humus layers, with soil weathering degrees generally higher than bedrock weathering degrees; (4) In addition to characteristics inherited from soil parent materials, elements in weathering crust profiles show content differentiation, characterized by enriched Al, K, and Se in humus layers, enriched Na, Fe, Si, Pb, Cu, Zn, Mn, As, Cd, Cr, and Hg in illuvial layers, and enriched Mg and Ca in soil parent material layers.

Figures and Tables | References | Related Articles | Metrics
Geophysical forecasting of deep reservoirs in the Z gas field
HE Xian-Ke, LOU Min, LI Bing-Ying, LIU Jiang, HU Wei, CAI Hua
Geophysical and Geochemical Exploration. 2024, 48 (3): 609-617.   DOI: 10.11720/wtyht.2024.1352
Abstract   HTML ( 1 )   PDF (12226KB)

Fine-scale characterization of reservoirs is critical for oil and gas exploration and production. Reservoirs in the Z gas field exhibit considerable burial depths and superposed sandstone and mudstone impedance characterized by dark spots, complicating their identification using conventional seismic methods. This study achieved the characterization of deep reservoirs in the Z gas field based on the dominant-channel stacking technique. First of all, this study analyzed the seismic response characteristics of deep reservoirs through forward modeling, positing that poor physical properties are the primary factor contributing to the formation of dark spots. Then, starting with the investigation of the near-well prestack gathers of the target layer, this study examined their amplitude variation with offset (AVO) characteristics and seismic phase stability at different angles, determining the dominant-angle seismic channels that can accurately reflect the phase stability of reservoirs. Finally, this study derived a lithology-sensitive 3D data volume through partial stacking of dominant-angle seismic channels, achieving the characterization of deep reservoirs. The near-trace superimposition (3°~15°) of phase-shift seismic data (-90°) allowed for effectively characterized the H3a reservoir in the Z gas field, providing a geophysical basis for subsequent well deployment. Therefore, the dominant-channel stacking technique can effectively characterize the spatial distribution of deep river-channel reservoirs, guiding the reservoir characterization of similar oil and gas fields.

Figures and Tables | References | Related Articles | Metrics
Multi-source frequency-domain seismic exploration technique and its application
SUN Hong-Lin, LIU Tie-Hua, LIU Tie, ZHANG Zhan-Rong, CHEN Zhi-Xing
Geophysical and Geochemical Exploration. 2024, 48 (3): 618-628.   DOI: 10.11720/wtyht.2024.1317
Abstract   HTML ( 1 )   PDF (5836KB)

Due to various strong electromagnetic mechanical interference and traffic barriers, many geophysical exploration techniques are ineffective in urban geophysical exploration.Based on transient surface waves,microtremor arrays,and microtremor spectral ratios,this study synthetically extracted two kinds of characteristic curves for joint inversion from the multi-source frequency-domain seismic data obtained by multi-point three-component low-frequency sensors.Consequently,this study achieved multi-source frequency-domain seismic exploration that integrated three techniques and developed the two-source synthetic dispersive spectrum extraction technique,the two-source characteristic curve joint inversion technique,and the equivalent homogeneous medium forward modeling technique based on inhomogeneous media.Engineering practice results demonstrate the improvements in the exploration accuracy and efficiency.

Figures and Tables | References | Related Articles | Metrics
Log-based identification of the types of the Maokou Formation carbonate reservoirs in the central Sichuan Basin
LIU Yu, WANG Liang, LUO Yang, SU Shu-Te, YAO Lin-Fang, LIU Yu-Chao, ZHOU Chun-Run, HU Meng-Die
Geophysical and Geochemical Exploration. 2024, 48 (3): 629-639.   DOI: 10.11720/wtyht.2024.1289
Abstract   HTML ( 0 )   PDF (9463KB)

The Maokou Formationcarbonate reservoirs in the central Sichuan Basinexhibit well-developed dissolutionpores, vugs, and fractures, pronounced heterogeneity, and diverse types. This study aims to identify their types and establish the log-based identification criteria for various reservoir types. First, this study classified the reservoir types based on the analysis of casting thin sections, core photos, and micro-resistivity imaging logs.Moreover, it determined the conventional log response characteristics of different reservoir types. Finally, it conducted log-based identification of reservoir types using the fracture porosity (φf) -secondary porosity index (RP) cross-plotting method. The results are as follows: (1)The Maokou Formation carbonate reservoirs in the central Sichuan Basin can beclassified into four types, i.e., fractured-vuggy, fractured-porous, porous-vuggy, and matrix porous reservoirs;(2) Fracture porosities calculated from different models are more similar in the case of more developed fractures, and dissolution pores and vugscan affect the fracture porositycalculation results to some extent;(3) The φf-RP cross-plotting method can effectively identify reservoir types. These research results provide technical support for the log-based identification of carbonate reservoir types.

Figures and Tables | References | Related Articles | Metrics
Deep structural characteristics of the Yagan fault zone in northeastern Ejina Banner, Inner Mongolia: Evidence from magnetotelluric sounding
WANG Wen-Jie, CHEN Lei, LEI Cong-Cong, SHI Xiao-Feng, YANG Biao, WANG Wen-Bao, SUN Da-Peng, XU Hao-Qing
Geophysical and Geochemical Exploration. 2024, 48 (3): 640-650.   DOI: 10.11720/wtyht.2024.1478
Abstract   HTML ( 3 )   PDF (14674KB)

There exists a continued debate concerning the spatial distribution and deep structural characteristics of the Yagan fault zone in northeastern Ejina Banner, Inner Mongolia. Adhering to the known-to-unknown research approach, this study completed five magnetotelluric sounding (MT) profiles. First, it delved into the relationship between the electrical structure characteristics of a MT profile (MT01) on the west side of the study area and the geological structure information of the Yagan fault zone within the profile. In terms of electrical characteristics, the Yagan fault zone was determined as a resistivity gradient zone characterized by northward dip, high dip angles, and deep depths. Based on these characteristics, and combined with the inversion interpretation results of four MT profiles (MT02~MT05) on the east side, this study identified the deep positions and structural characteristics of the Yagan fault zone within all the MT profiles. Moreover, it determined the major electrical directions of all the MT profiles using the impedance tensor decomposition technique, and the spatial trend of the Yagan fault zone based on the two-dimensional inversion interpretation results. As revealed by the results, the Yagan fault zone within the study area exhibits an overall nearly EW strike at the shallow surface and a strike of NE45° in the deep part, with an average width of approximately 6.8 km. It is a reverse fault with a gradual arc deflection to the north from west to east, manifesting a generally northward dip direction, dip angles ranging from 60° to 67°, and a fault depth of about 20 km. The obtained deep electrical structure model effectively reveals the deep structural characteristics of the study area. providing certain reference significance for the study of regional tectonic evolution

Figures and Tables | References | Related Articles | Metrics
Application of high-density electrical resistivity tomography and audio magnetotellurics for groundwater exploration in the karst area in southwestern China
XIA Shi-Bin, LIAO Guo-Zhong, DENG Guo-Shi, YANG Jian, LI Fu
Geophysical and Geochemical Exploration. 2024, 48 (3): 651-659.   DOI: 10.11720/wtyht.2024.1237
Abstract   HTML ( 2 )   PDF (5894KB)

Huize County of Yunnan Province is situated in the karst area in southwestern China, where karst groundwater is its primary water source. To conquer local difficulties in drinking water, this study constructed a conceptual model of groundwater occurrence by fully investigating the hydrogeological conditions of the Huize area. Moreover, this study evaluated the applicability and optimal combination of geophysical methods based on the measurement results of petrophysical properties. According to the actual local needs, this study deployed a comprehensive profile combining high-density electrical resistivity tomography (HDERT) and audio magnetotellurics (AMT) in Tuogu Village, Huize County. The groundwater enrichment site was delineated relying on resistivity anomalies, effectively guiding the layout of boreholes. The boreholes achieved the maximum single-borehole water yield of 20.76 m3/d, thus effectively alleviating the local drinking water problem. The HDERT-AMT combined exploration method proves to be optimal for prospecting for groundwater in carbonate rock areas. HDERT can accurately characterize weathered layer thicknesses, bedrock boundaries, fissure evolutionary degrees, and water-bearing properties of strata, constraining groundwater recharge channels, thus counteracting AMT's defects for identification of near-surface stratigraphic structures. AMT can accurately reflect the spatial structures of fracture zones and the macrostructures of strata, limiting the boundary conditions (aquicludes) of water-bearing structures, thus making up for the defects of insufficient detection depths of HDERT in high-resistivity stratigraphic regions. HDERT and AMT, which are complementary to each other in terms of accuracy and depth, can be applied to identify and constrain the spatial occurrence conditions of groundwater migration, storage, and enrichment.

Figures and Tables | References | Related Articles | Metrics
REE geochemical anomalies in soils of the Ximeng-Lancang area in southwestern Yunnan and their discovery and their implications for ore prospecting
XIE Kui-Rui, SONG Xu-Feng, ZHOU Kun, ZHOU Yu-Guo, SHE Zhong-Ming, TANG Jian
Geophysical and Geochemical Exploration. 2024, 48 (3): 660-667.   DOI: 10.11720/wtyht.2024.2014
Abstract   HTML ( 1 )   PDF (2521KB)

The Ximeng-Lancang area in southwestern Yunnan resides in the southern section of the Nujiang-Lancangjiang-Jinshajiang orogenic belt in Southwest China. The 1∶50,000 geochemical soil survey revealed 24 rare-earth-element (REE) geochemical anomalies, which are primarily distributed in the Carboniferous Pingzhang Formation mafic volcanic rocks and the Carboniferous-Permian Yutangzhai Formation sedimentary carbonate rocks within and near the Changning-Menglian deep fault zone. Furthermore, the AP00 REE geochemical anomalies ranking high in the evaluation were analyzed in detail through a 1∶10,000 geochemical soil survey, a 1∶10,000 special geological survey, and light-duty prospecting engineering in mountainous areas. A new type of REE ores in weathering crusts has been first discovered in sedimentary carbonate strata, with preliminarily estimated REE resources reaching a medium scale, suggesting a prospecting breakthrough. This finding shows a new prospecting approach, which can be referenced for similar research. As revealed by a comprehensive analysis of the regional geological and geochemical settings and the data of AP00 REE anomalies, the AP00 REE ores in weathering crusts have undergone a gradual enrichment and mineralization process involving four different geological processes, suggesting polygenetic compound REE ores. Considering the low leaching efficiency of AP00 REE ores and significant structural (magmatic) superimposed mineralization of the heavy REE yttrium, it is inferred that yttrium-dominated primary REE ores might exist in the deep part, implying high potential for heavy-REE ores.

Figures and Tables | References | Related Articles | Metrics
Application of comprehensive geophysical prospecting to groundwater exploration in Ritu County of the Ali area
CHEN Yong-Ling, JIANG Shou-Jin, XIE Dan, WANG Jia, HE Zhi-Xiong, LIU Cheng
Geophysical and Geochemical Exploration. 2024, 48 (3): 668-674.   DOI: 10.11720/wtyht.2024.2485
Abstract   HTML ( 1 )   PDF (3140KB)

Surface water resources are scarce in Ritu County of the Ali area due to the absence of large rivers. The strata in the area are primarily composed of Jurassic and Cretaceous sedimentary rocks, exhibiting significantly varying spatial water abundance, thus posing challenges in water exploration through drilling. Based on hydrogeological survey data, this study summarized the occurrence patterns of pore water in Quaternary unconsolidated rocks and fissure water in fault structures and the electrical characteristics of aquifers in the area. It explored the structural fissure water with high water abundance in the area using the high-density resistivity method and the audio magnetotelluric method. Based on the geophysical exploration results, it delineated favorable aquifers. Furthermore, it verified the exploration accuracy through drilling, obtaining high-yield water wells, and ensuring the supply of drinking water. Therefore, the combination of multiple geophysical exploration methods is effective in groundwater resource surveys, improving the exploration accuracy of groundwater resources and providing effective technical support for well deployment.

Figures and Tables | References | Related Articles | Metrics
Deep-hole verification of wide-field electromagnetic method-derived results in the Zhengtun area of the Liaodong region
LIANG Wei-Tian, LI Di-Quan, SUN Xin-Sheng, WANG Dong-Bo, FENG Jia-Xin, LI Hao, FAN Jin-Hu
Geophysical and Geochemical Exploration. 2024, 48 (3): 675-683.   DOI: 10.11720/wtyht.2024.1428
Abstract   HTML ( 0 )   PDF (5860KB)

The development of gold deposits in the Liaodong region is considered to be controlled by the superimposed detachment fault zone of the metamorphic core complex system. The traditional view holds that the thickness of the cap rocks of the Yongning Formation in the Yongning Basin can exceed thousands of meters, thus hindering the migration of ore-bearing fluids and the formation of large-scale metal deposits. The exploration of deposits in the Liaodong region has remained within a depth of 1 km due to limited exploration efforts and insufficient research. This study obtained the resistivity distribution characteristics within a depth of 3 km in the Zhengtun area using the wide-field electromagnetic method (WFEM), ascertaining that the thickness of the cap rocks in the Liaodong region is around 1 km, in sharp contrast to the extremely thick cap rocks in the Yongning Formation. As verified by the 2 km deep drilling, an unconformable contact between the Yongning Formation and the underlying Archean basement was observed at a hole depth of 1 345 m, without significant structural detachment near the boundary. This study demonstrates that the thickness of the cap rocks in the Yongning Basin is merely around 1 km. Considering multistage active fault structures and densely distributed hypabyssal rock vein swarms in the area, it is preliminarily determined that the geological setting for mineralization in the Yongning Basin is akin to that of the Jiaodong gold ore concentration area. The ore-bearing metamorphic fluids or magmatic-hydrothermal fluids might have migrated to the upper part of the boundary for mineralization during the destruction of the North China craton. Overall, the Liaodong region has the potential to achieve breakthroughs in polymetallic prospecting, and the WFEM pinpoints the deep mineralization prediction.

Figures and Tables | References | Related Articles | Metrics
Anisotropic characteristics beneath Tibetan Plateau and its surrounding areas
GAO Ling-Xia, FENG Bin, LIANG Meng, WU Wen-Li, SUN Yue
Geophysical and Geochemical Exploration. 2024, 48 (3): 684-689.   DOI: 10.11720/wtyht.2024.1355
Abstract   HTML ( 0 )   PDF (4965KB)

This study conducted SKS shear-wave splitting measurements of 39 distant earthquakes with magnitudes above 5.8 and epicentral distances between 88° and 120° recorded by the monitoring stations of China Earthquake Networks Center in the Qinghai-Tibet region in the past five years. Based on these measurements, this study investigated the anisotropic and deformation characteristics of Tibetan Plateau and its surrounding areas. Within the Qinghai-Tibet region, the fast axis of SKS shear-wave splitting measurements from west to east gradually shifted from NE-SW to E-W and then to NNW, roughly aligning with the direction of the GPS velocity field and changing in a clockwise direction. The reason for the measurement results in this region lies in that the westward retreating of the Burma plate during the eastward subduction may have caused circular deformation in the local lithosphere. The GPS data of the southern Sichuan-Yunnan region reveal nearly ES-directed surface deformation and NW-SE-trending strike-slip faults, with the fast-axis direction of the Pms wave for crustal anisotropy being S-N or NNE-SSW. The SKS splitting measurement results of this study reveal the E-W-directed anisotropy of the upper mantle, which intersects at a high angle with or is perpendicular to the fast-axis direction of the Pms wave. This suggests that the mantle flow field of the deep asthenosphere in Yunnan is inconsistent with the deformation characteristics of the crust and surface, and the mantle and crust show distinct deformation mechanisms and anisotropy sources, resulting in decoupling deformation.

Figures and Tables | References | Related Articles | Metrics
Determining double-layer goafs in coal mines using CSAMT-derived apparent resistivity and impedance phase
QIN Chang-Chun, NIU Zheng, LI Jing
Geophysical and Geochemical Exploration. 2024, 48 (3): 690-697.   DOI: 10.11720/wtyht.2024.1338
Abstract   HTML ( 2 )   PDF (4081KB)

The goaf and subsidence areas formed ue to the mining of subsurface coal seams can cause damage to surrounding ecological environments.At present, the detection effects of double-layer goafs in coal mines, especially the second-layer goafs, are unsatisfactory. In response to this challenge, this study delineated goafs using apparent resistivity and impedance phase derived from the data acquired by an efficient controllable source audio-frequency magnetotelluric instrument. In the case of a shallow water-bearing goaf with low resistivity, the apparent resistivity displays shadow effects, leading to an extended abnormal range of the upper target, which is unfavorable to the identification of the lower high-resistivity goaf. In contrast, the impedance phase, exhibiting minor shadow and static effects, shows a significant response to the lower goaf. As indicated by the theoretical model testing results, the combination of apparent resistivity and impedance phase can effectively determine shallow water-bearing goafs and deep unfilled high-resistivity goafs. This combination method was employed to interpret the double-layer goaf in the Shenfu mining area of the Jurassic coal field in northern Shaanxi, achieving satisfactory results through the mutual verification of the two parameters. Engineering verification results indicate that this method demonstrates reliable inference and expected exploration effects. Overall, this method provides a new approach for CSAMT-based inference and interpretation in the exploration of double-layer goafs in coal mines, thus holding critical technical promotion and reference significance.

Figures and Tables | References | Related Articles | Metrics
The calculation and application of a near-surface Q-value model based on dual-well micrologs for a loess tableland area
XIA Chang-Liang, DAI Hai-Tao, LI Guo-Qiang, GU Fa-Ming, WU De-Ming, HAN Li
Geophysical and Geochemical Exploration. 2024, 48 (3): 698-704.   DOI: 10.11720/wtyht.2024.1227
Abstract   HTML ( 0 )   PDF (11493KB)

Given the low resolution and poor wavelet coherence of seismic data for the loess tableland area of the Ordos Basin, this study proposed a method for calculating the near-surface Q-value model for near-surface Q-absorption compensation of seismic data. Investigations reveal that micrologs have been used to obtain the Q field of a whole survey area by calculating the Q value and subsequent interpolation. Based on previous research results, this study calculated the Q values of well sites and near-surface velocity values using dual-well micrologs. Then, the regional relationship function between near-surface velocity and Q was determined through fitting using the least squares method. Furthermore, the near-surface Q field of the study area was obtained using the near-surface velocity field derived from the tomographic inversion of the first arrival wave post basic static correction. Consequently, the near-surface Q field of the whole survey area were calculated from the Q values of microlog positions, and the near-surface Q absorption compensation of prestack gathers was achieved. As indicated by the application of the study area’s seismic data, which are characterized by complex surface and subsurface conditions, the inversion of the Q field for near-surface Q absorption compensation using the method proposed in this study can effectively enhance the wavelet coherence of seismic data, broaden the frequency band, improve the log-seismic matching relationship, and eliminate the influence of near surface on seismic wavelets.

Figures and Tables | References | Related Articles | Metrics
An improved butterfly optimization algorithm in the inversion of Rayleigh wave dispersion curve
PENG Liu-Ya, FENG Wei-Dong, XIE Hui-Ting, LI Fei, YANG Yuan-Yuan, CAO Jun-Feng, REN Chuan
Geophysical and Geochemical Exploration. 2024, 48 (3): 705-720.   DOI: 10.11720/wtyht.2024.1116
Abstract   HTML ( 0 )   PDF (6312KB)

Due to the multiplicity of solutions and the multiple extrema of the inversion objection functions,conventional nonlinear optimization algorithms are susceptible to unstable convergence and local optimum in the inversion of Rayleigh wave dispersion curves.This study improved the standard butterfly optimization algorithm by incorporating dynamic switch probability and nonlinear self-adaptive weight factors,yielding an elevated global exploration capacity in the early stage and a high local research ability in the latter stage.Furthermore,the dimension-by-dimension Cauchy mutation,along with a greedy algorithm,was employed to update the current best position during each iteration,ultimately directing the whole swarm population toward the global optimum.Tests of four commonly used benchmark functions demonstrate that the improved butterfly optimization algorithm(IBOA) outperformed other nonlinear algorithms,including the genetic algorithm and particle swarm optimization algorithm,in terms of the global research capacity of both unimodal and multimodal functions.Different algorithms were adopted for the inversion of the dispersion curves of three theoretical geological models.The results show that IBOA yielded inversion results that were closer to the models even when the dispersion curves contained 10% random noise.Finally,the IBOA was applied to actual Rayleigh wave data,and the inversion results were highly consistent with the strata revealed by drilling.Compared with the genetic algorithm and the particle swarm optimization algorithm,the IBOA significantly improved the convergence speed,as well as solution accuracy and stability.Therefore,the IBOA has a certain practical value and application prospects.

Figures and Tables | References | Related Articles | Metrics
Distribution patterns of the electromagnetic fields of orthogonal horizontal magnetic dipoles as sources in CSRMT
CHEN Xing-Peng, WANG Liang, LONG Xia, XI Zhen-Zhu, QI Qing-Xin, XUE Jun-Ping, DAI Yun-Feng, HU Zi-Jun
Geophysical and Geochemical Exploration. 2024, 48 (3): 721-735.   DOI: 10.11720/wtyht.2024.1395
Abstract   HTML ( 1 )   PDF (7800KB)

Controlled source radio-magnetotellurics (CSRMT) measurements typically use artificial field sources transmitting at frequencies ranging from 1 to 1 000 kHz. Among the many transmitting sources of the artificial source electromagnetic method, the orthogonal horizontal electric dipole source and the orthogonal horizontal magnetic dipole source are preferred field sources for tensor resistivity measurements. Hence, using the analytical formulas for electromagnetic fields based on the horizontal electric dipole source and the horizontal magnetic dipole source, this study calculated the electromagnetic fields based on the orthogonal horizontal electric dipole source and the orthogonal horizontal magnetic dipole source in the homogeneous half-space model. The results show that: (1) The displacement current needs to be considered at transmitting frequencies above 100 kHz; (2) The effects of displacement current on the tensor apparent resistivity and the impedance phase can be ignored in the far zone; (3) With a constant model resistivity and varying distances between transmitter and receiver, model calculations indicate a larger measurement range in the far zone of the high-frequency electromagnetic field; (4) With a constant distance between transmitter and receiver and varying model resistivities, model calculations suggest that the far-zone range of the electromagnetic field is significantly influenced by resistivity, and that the high-resistivity model requires higher frequencies for achieving far-zone observation conditions.Compared with the electric dipole source, the magnetic dipole source exhibits smaller deviations on the tensor apparent resistivity and impedance phase with the actual value, which is more suitable for geological analysis.

Figures and Tables | References | Related Articles | Metrics
Exploring the shear-wave prediction method for complex lithologic assemblages of the Fengcheng Formation in the Mahu sag
ZHONG Hou-Cai, LIU Zhen-Yu, ZHU Zhe, QU Lin, ZHANG Shan, YAO Yan-Fei, FAN Rong-Rong
Geophysical and Geochemical Exploration. 2024, 48 (3): 736-746.   DOI: 10.11720/wtyht.2024.1179
Abstract   HTML ( 0 )   PDF (9611KB)

Research on shear-wave prediction for complex lithologic assemblages of the Permian Fengcheng Formation in the Mahu sag is critical but challenging for accurately identifying hydrocarbon accumulation zones in the sag.The key to the prediction is to make breakthroughs in petrophysical modeling based on different lithologies.Given various lithologic types and intricate mineral compositions,this study delved into petrophysical modeling based on different lithologies.Consequently,this study developed an interval-,lithology-,and model-specific shear-wave prediction technique for complex lithologies.Furthermore,it established a technique for building a dry rock matrix for alkali lake-type dolomitized tight reservoirs by highlighting the major rock mineral compositions and merging the same types of rock mineral compositions.Additionally,the self-consistent model was selected for shear-wave calculation in the petrophysical modeling of dolomitized sandstone reservoirs.These techniques have been applied in the Fengcheng Formation of the Mahu Sag,achieving encouraging application results in both the shear-wave prediction of complex lithologic assemblages and the prediction of sweet spots.This study will provide a basis for well deployment and reserves determination in the area and offer valuable experience for oil and gas exploration in similar areas.

Figures and Tables | References | Related Articles | Metrics
Predicting the spatial distribution of soil organic matter using the model consisting of the Boruta algorithm and the optimized GA combined with the geostatistical method
GAO Peng-Li, REN Da-Lu, LI Chao-Hui, FENG Zhi-Qiang, MIAO Hong-Yun, QIAO Lin, WANG Jian-Wu, YANG Yong-Liang, ZHANG Li-Ming, LI Guang-Hui
Geophysical and Geochemical Exploration. 2024, 48 (3): 747-758.   DOI: 10.11720/wtyht.2024.1114
Abstract   HTML ( 0 )   PDF (4424KB)

Establishing a spatial prediction model for soil organic matter (SOM) can accurately predict the spatial distribution of SOM content, playing a significant role in scientific soil management and ecosystem service enhancement. Focusing on the soils in Yonghe County, Linfen City, Shanxi Province, this study extracted topographic factors and vegetation indices from the digital elevation model (DEM) and vegetation remote sensing data. With soil attributes as variable factors, this study, using the Boruta algorithm, selected the characteristic variablescorrelating strongly with SOM from variable factors as auxiliary variables. These auxiliary variables were used as model inputand the measured SOM values as model output.The SOM content in samples in the training set was predicted usingthe ordinary Kriging (OK)method, the back propagation neural network (BPNN), the genetic algorithm-optimized BPNN (GA-BPNN), and the improved BPNN combined with the geostatistical method (the GA-BPNN-OK method) separately. The prediction accuracy was comparatively analyzed based on samples in the validation set. The results show that: (1)The Boruta algorithm ranked the selected characteristic variables in order of importance, obtaining the sequence of total nitrogen >topographic wetness index (TWI) > elevation > slope > normalized difference vegetation index (NDVI) > enhanced vegetation index (EVI); (2)Despite local differences,the SOM prediction results obtained using the four methods exhibited roughly the same overall spatial distribution: low in the western and southwestern portions of the study areabut high in the eastern and southeastern portions;(3)Compared to the other three models, the GA-BPNN-OK model demonstrated more distinct low- and high-value areas in the predicted SOM distribution. (4) As revealed by the comparison of prediction accuracy indices, the GA-BPNN-OK method yielded a minimum root mean square error (RMSE) of 0.059, a minimum mean absolute error (MAE) of 0.240,a minimum mean relative error (MRE) of 0.165, and a maximum fitting coefficient (R2) of 0.78. To verify the effects of the Boruta algorithm in improving model accuracy, global variables, as well as the variables determined through characteristic selection, were used as the model inputof the GA-BPNN method. The comparison of the prediction results indicates that the Boruta algorithm reduced the model error. Therefore, the Boruta algorithm and the GA-BPNN-OK method constitute the optimal prediction model for the spatial distribution of SOM content.

Figures and Tables | References | Related Articles | Metrics
Intelligent inversion of magnetotelluric data based on improved DenseNet
YAO Yu, ZHANG Zhi-Hou
Geophysical and Geochemical Exploration. 2024, 48 (3): 759-767.   DOI: 10.11720/wtyht.2024.1275
Abstract   HTML ( 0 )   PDF (4789KB)

Magnetotelluric (MT) sounding is a vital exploration method in tunnel engineering. Inversion methods can assist geologists in interpreting geological data by converting MT data into geoelectric parameters. However, conventional inversion methods exhibit inferior timeliness and reliance on initial model settings. In this study, deep learning was applied to the one-dimensional inversion of magnetotelluric data. First, an improved DenseNet model was constructed and trained to invert geological models of various resistivity-variable strata, yielding a fast computational speed and high accuracy. Then, the robustness of the improved DenseNet model was tested, suggesting that its network structure can achieve satisfactory inversion results for noisy data. Finally, this artificial intelligence technique was applied to the MT data inversion of the Hongjiaqian tunnel in the Huangshan area, obtaining geophysical exploration results that match the geological research results. Additionally, relevant construction recommendations were given based on the inversion results.

Figures and Tables | References | Related Articles | Metrics
Prediction of oil column heights in fault-controlled tabular reservoirs through time-frequency analysis based on improved generalized S-transform
YUAN Xiao-Man, LI Xiang-Wen, ZHANG Jie, DAN Guang-Jian, LU Zhong-Yuan, HAN Chong-Yang, ZHANG Lei, XU Jian-Yang
Geophysical and Geochemical Exploration. 2024, 48 (3): 768-776.   DOI: 10.11720/wtyht.2024.1321
Abstract   HTML ( 2 )   PDF (6903KB)

The fault-controlled carbonate area in the northern depression of the Tarim Basin possesses abundant oil and gas resources.Identifying the oil-water contact (OWC) of fault-controlled tabular reservoirs is critical for their effective exploitation.However,OWC identification through drilling is costly and challenging.In contrast,it is efficient to identify the OWC using geophysical methods.This study proposed a time-frequency analysis method based on generalized S-transform.As revealed by the joint analysis of extensive time-frequency analysis results of through-well seismic channels and production performance analysis data,the depth/time-varying main frequency of seismic data is positively correlated with the oil layer thickness.Hence,this study proposed to identify the OWC using the abnormal inflection point of the energy envelope of seismic channel time-frequency gather.Experimental results demonstrate that oil layer thickness results obtained are uncertain,generally reliable,and reliable in the case of oil column height (OCH)<120 m,120 m≤OCH≤250 m,and OCH≥250 m,respectively.The method proposed in this study was applied to a fault fracture zone of an area of the Fuman oilfield,obtaining the main predicted oil layer thicknesses between 200 m and 520 m,aligning with the actual exploitation results.Therefore,the method of this study can be employed to guide exploitation.

Figures and Tables | References | Related Articles | Metrics
Critical factors in microtremor-based exploration at a depth of thousands of meters
QI Juan-Juan
Geophysical and Geochemical Exploration. 2024, 48 (3): 777-785.   DOI: 10.11720/wtyht.2024.1358
Abstract   HTML ( 2 )   PDF (6323KB)

To explore the critical factors influencing the results of microtremor-based exploration at a depth of thousands of meters,this study conducted experiments using triangular arrays based on spatial autocorrelation(SPAC) and extended SPAC(ESPAC).Focusing on factors such as array size,acquisition unit frequency,and acquisition duration,this study explored the frequency band ranges corresponding to different array sizes,the arrangement of arrays in kilometer-depth exploration for obtaining both deep and shallow data,and the improvement in deep resolution.Based on the analysis and discussion results,this study established a parameter-setting system to improve the accuracy of exploration at a depth of thousands of meters.

Figures and Tables | References | Related Articles | Metrics
An observation device based on asymmetric design for high-density resistivity imaging
PANG Yong-Hao, SHEN Zhao-Ang, CHANG Zhi-Xi, LI Guang-Chang, CHEN Mei, XIE Zhi-Wei, WANG Wei
Geophysical and Geochemical Exploration. 2024, 48 (3): 786-793.   DOI: 10.11720/wtyht.2024.1454
Abstract   HTML ( 0 )   PDF (5600KB)

For the high-density resistivity method, favorable grounding conditions are required to ensure the establishment and measurement of the geoelectric field. Otherwise, unfavorable grounding conditions, like rigid pavement, will prevent some electrodes from being inserted into the ground, leading to the loss of valid data from standard observation devices and reducing the imaging quality. Therefore, this study proposed a method for the fast observation device design. This method supplemented data using an asymmetric quadrupole electrode array according to the spatial positions of missing data's recording points. Numerical simulations show that the method proposed in this study significantly improved the imaging effects of Wenner, Schlumberger, and dipole-dipole arrays, with a second-scale design time. In this study, an observation device based on asymmetric design for high-density resistivity imaging was successfully applied to the embankment detection in Ningbo, reducing the influence of motor lanes on data quality and accurately locating the embankment position.

Figures and Tables | References | Related Articles | Metrics
Research and application of the velocity modeling method for the eastern margin of the Pre-Caspian Basin
WANG Zhen, JI Zhi-Feng, ZHANG Yi-Qiong, WANG Xue-Ke, JIANG Li, LIN Ya-Ping, KONG Ling-Hong, ZHANG Ming-Jun
Geophysical and Geochemical Exploration. 2024, 48 (3): 794-803.   DOI: 10.11720/wtyht.2024.1165
Abstract   HTML ( 1 )   PDF (12808KB)

The low-amplitude structures on the top of the Carboniferous carbonate rocks in the Akzor area on the eastern margin of the Pre-Caspian Basin show considerable potential for oil and gas exploration.However,the complex distribution of overlying Lower Permian strata and significant changes in lateral velocities pose high challenges for the mapping of the Carboniferous low-amplitude structures.To achieve the rapid mapping of the structures in the study area,this study selected the frequency-division interval velocity inversion method to build the velocity model for the study area after comparing three methods for velocity modeling.The velocity model built in this study,solving the problem that the frequency-division interval velocity inversion is constrained by the lateral continuity of conventional interval velocity inversion methods,yielded more accurate velocity characterization of anomalies in the Lower Permian carbonate rocks.Moreover,compared to the collaborative velocity modeling method based on well-seismic velocity spectra and the conventional interval velocity inversion method constrained by log data,the frequency-division interval velocity inversion method effectively improved the depth-domain mapping accuracy of the underlying Carboniferous low-amplitude structures in the study area,boasting high performance.

Figures and Tables | References | Related Articles | Metrics
Data integration based on MapGIS and ASCII code files
ZHAO Hong-Yan, LI Cong, CHANG Qiu-Ling, GUAN Xiao-Rong, DU Cheng-Yuan, CHEN Xin, WANG Jing
Geophysical and Geochemical Exploration. 2024, 48 (3): 804-811.   DOI: 10.11720/wtyht.2024.1367
Abstract   HTML ( 4 )   PDF (3914KB)

Data integration based on MapGIS includes data conversion, data normalization, data fusion, and related research. A synthesis of existing research suggests that data conversion has been intensively studied, while there is a lack in studies of data normalization and data fusion. This study improved the data normalization method based on the complex and extensively applied geological maps, achieving the normalized annotation and color filling for thousands of geobodies at one time. A technical process for data fusion was established by analyzing the applicable conditions of various commonly used methods for data fusion and making some supplementation. Besides, ASCII code files were prepared for mapping small coal pillars in batches. The results of this study show that improving the data normalization method, establishing the technical process for data fusion, and making full use of ASCII code files can significantly enhance the efficiency of data integration and broaden the mind for problem solving.

Figures and Tables | References | Related Articles | Metrics
A data augmentation method for semi-airborne transient electromagnetic noise based on a generative adversarial network
FENG Wei, FENG Hao, XIAO Li-Jiang, CHEN Pin-Ming, LIU Dong, WANG Yong-Xin, ZHOU Xiao-Sheng, SUN Huai-Feng, WANG Zhen
Geophysical and Geochemical Exploration. 2024, 48 (3): 812-819.   DOI: 10.11720/wtyht.2024.1211
Abstract   HTML ( 0 )   PDF (3533KB)

The semi-airborne transient electromagnetic (SATEM) noise data, exhibiting intricate forms, high acquisition costs, and small volumes, cannot be augmented using conventional augmentation methods, thus significantly hindering the subsequent denoising work. Hence, this study proposed a data augmentation method for SATEM signals based on the generative adversarial network (GAN). By designing the generator as a long short-term memory (LSTM) network and training the generator and discriminator models based on the dataset of real-measured SATEM noise, this study obtained a generator model that can generate simulated noise data. Then, this study analyzed the distributions of the simulated noise generated by the generator and the real-measured noise. Moreover, this study compared the performance of the denoising network before and after augmentation, demonstrating the effectiveness of this method for augmenting real-measured SATEM noise data.

Figures and Tables | References | Related Articles | Metrics
Distributions, enrichment characteristics, and sources of heavy metals in soils in Fangshan District, Beijing
HAN Bing, HUANG Yong, LI Huan, AN Yong-Long
Geophysical and Geochemical Exploration. 2024, 48 (3): 820-833.   DOI: 10.11720/wtyht.2024.1153
Abstract   HTML ( 1 )   PDF (9140KB)

Heavy metal pollution in soils has become increasingly prominent. To explore the distributions of heavy metals in soils in Fangshan District, Beijing, China, this study collected 152 topsoil samples and 240 deep soil samples from this district. Based on these samples, this study statistically analyzed the distributions and enrichment factors (EF) of seven heavy metal elements, namely As, Cd, Cr, Cu, Hg, Ni, and Pb. Furthermore, this study investigated the correlations, sources, and contribution rates of these elements through principal component analysis (PCA) and positive matrix factorization (PMF). The results show that: ① Elements As, Cd, Cu, Ni, and Pb exhibit high contents in the topsoil of the Shidu, Shijiaying, Xiayunling, and Puwa areas. Besides, elements Cr, Ni, and As manifest high contents locally in Zhoukoudian, Nanjiao, and Hebei Town. Element Hg displays high content in the eastern plain areas including Doudian, Yancun, and Changyang; ② Elements Hg and Cd are highly enriched, and there exist strong corrections among elements As, Cr, and Ni; ③ These elements primarily originate from natural sources (soil parent materials), which contribute to 73.6% to 78.6% of the elements. Element Cd is mostly sourced from an anthropogenic mixed source, which contributes 83.3% of Cd. The mixed source predominantly consists of industrial and mining activities, agricultural production, and traffic emissions. Elements Cu and Pb showed similar contribution rates of natural and mixed sources, both about 50%. Element Hg in soils primarily stems from dry and wet atmospheric deposition, which yields a contribution rate of 72.4%.

Figures and Tables | References | Related Articles | Metrics
Analysis of soil heavy metal influencing factors and sources in typical small watersheds in shallow mountainous area
SHI Jing-Tao, LIU Jun-Jian, ZHANG Jun-Chao, WANG Jiang-Yu-Long, JIANG Yu-Ge, WANG Mo, LI Heng-Fei, YANG Wen-Hao, YAN Xiang-Jin
Geophysical and Geochemical Exploration. 2024, 48 (3): 834-846.   DOI: 10.11720/wtyht.2024.1270
Abstract   HTML ( 0 )   PDF (6471KB)

This study investigated the contents of eight heavy metals and related oxides in rocks with different lithologies and the soils formed in the Puhe river basin of Pingquan City. Based on the above investigation, this study analyzed the influencing factors and sources of soil heavy metals in the typical small watershed of the shallow mountainous area, aiming to provide theoretical support for water conservation and ecological restoration in the Beijing-Tianjin-Hebei region. Based on the contents and spatial distributions of soil heavy metals and combined with regional geological setting, this study delved into the influencing factors and sources of heavy metal elements in topsoil, deep soil, and soil parent materials using multiple statistical methods. The results show that heavy metals in topsoil and deep soil exhibited relatively similar contents and coupled spatial distributions. In terms of vertical distributions, the correlation coefficients of heavy metals were negative between topsoil and soil parent materials but positive between deep soil and soil parent materials. As indicated by the results, in the topsoil, elements Cr, Ni, Cu, Zn, and Pb are primarily derived from soil parent materials, while elements Cd, Hg, and As are subjected to the influence of mining. In contrast, the eight heavy metals in the deep soil predominantly stem from soil parent materials, with anthropogenic factors contributing to Cd and As.

Figures and Tables | References | Related Articles | Metrics
Sources of soil heavy metals and health risk assessment of crops in arable land at the periphery of a typical mercury mining area
YU Fei, WANG Rui, ZHOU Jiao, ZHANG Feng-Lei, JIANG Yu-Lian, ZHANG Yun-Yi, ZHU Shi-Lin
Geophysical and Geochemical Exploration. 2024, 48 (3): 847-857.   DOI: 10.11720/wtyht.2024.1313
Abstract   HTML ( 2 )   PDF (3441KB)

This study aims to systematically assess the pollution risk of heavy metals in the soil-crop-human body system along the periphery of mining areas, thus providing a scientific basis for the classified management of ecological risks and safe crop production in mining areas. Hence, this study examined the soil and crops (rice, corn, and sweet potato) in arable land along the periphery of a typical mercury mining area in Chongqing City. The single-factor pollution index (Pi), Nemero composite index (P), and positive matrix factorization (PMF) model were employed to assess the pollution degree and ecological risk of soil heavy metals for source analysis. Moreover, the human health risk assessment model recommended by the United States Environmental Protection Agency (USEPA) was applied to assess the health risks of local staple crops for residents. The results are as follows: (1) The average contents of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in the soil of the study area were all higher than the topsoil background values of Chongqing and China, suggesting that heavy metals are relatively enriched in topsoil; (2) The single-factor pollution index indicates that the over-limit ratios of Hg and Cd in the soil reached 96.29% and 92.59%, respectively, whereas rice, corn, and sweet potato samples with Cd content exceeding the value specified in the national food safety standard (GB 2762—2022) accounted for 16.67%, 18.75%, and 14.28%, respectively; (3) The Nemero composite index (P) was between 1.17 and 46.05, suggesting mild to heavy pollution in the study area, with heavy pollution primarily located around the mercury mining area and artisanal mercury smelters, as well as the lower reaches of the Rongxi River; (4) The PMF model analysis demonstrates that the heavy metals in the soil of the study area originate from three sources: natural source (47.21%), mining activities (16.00%), and a mixed source of mining and agricultural activities (36.79%). Specifically, Cd, Cr, and Ni are principally affected by the natural source, Hg by mining activities, As and Pb by the mixed source of mining and agricultural activities, and Cu and Zn are associated with the natural source and the mixed source of mining and agricultural activities; (5) The human health risk model reveals that the consumption of rice, corn, and sweet potato poses composite health risks for both adults and children. Rice consumption exhibits the highest risk index, especially in children, with the main risk factors being As and Cd.

Figures and Tables | References | Related Articles | Metrics
The migration,transformation and ecological effects of heavy metals in soil-cropsystem in Lipu, Guangxi
JIANG Yu-Xiong, WEN Mei-Lan, PAN Qi-Ming, JIANG Bo-Chang, WANG Zhong-Wei
Geophysical and Geochemical Exploration. 2024, 48 (3): 858-867.   DOI: 10.11720/wtyht.2024.3686
Abstract   HTML ( 1 )   PDF (4245KB)

In order to understand the content and distribution characteristics of heavy metals in soil and crops in Lipu,soil and crops (rice, Lipu taro, citrus, water chestnut) were collected. Todetermine the pH value of soil samples and the total amount of As, Cd, Cr, Hg, Ni, Pb, Cu, Zn and the form content of As, Cd, Cr, Hg, and Pb.The content of As, Cd, Cr, Hg, Pb in crop samples was measured.The bioconcentration factor (BCF) of heavy metal elements was calculated. The migration and transformation and ecological effects of heavy metal in the soil-crop system are analyzed. The results showed that:① The topsoil in the study area is predominantly acidic in the study area. The average contents of As, Cd, Cr, Hg, Ni, Pb, Cu, and Zn in the surface soil in the area were 13.57×10-6, 0.33×10-6, 87.06×10-6, 0.153×10-6, 27.49×10-6, 30.46×10-6, 27.94×10-6, 82.53×10-6.Respectively, all of which were higher than the national soil background values.②The heavy metal content in rice crops is higher than that in Lipu taro, citrus, and horseshoe.The heavy metal content is also different in rice roots, stems, and seeds.③ The bioaccumulation coefficient of heavy metal was generally high in rice. When comparing different parts of rice, the bioconcentration coefficients of heavy metals were greatest in the roots and least in the seeds. And when comparing different crops, the migration capacity of heavy metals in the soil-rice system was significantly higher than that of Lipu taro, citrus and water chestnut.④ The exchangeable state of Cd in the study area is significantly higher than As, Cr, Hg, and Pb. Cd is the most active soil heavy metal in the study area, it should be paid more attention to prevent excessive Cd in crops from causing harm to people.

Figures and Tables | References | Related Articles | Metrics
Assessing radiation levels in the environment by converting total natural gamma radiation into the absorbed dose rate in air: A case study of measured data from Panjia Village, Guiyang County and Tuqiao Village, Yongxing County
LIU Jun-Feng, PENG Wen-Biao, TAO Feng, MENG Fan-Xing, WEI Guang-Jing, LIU Hong, DENG Ju-Zhi, CHEN Hui, FU Chen, WANG Pei-Jian
Geophysical and Geochemical Exploration. 2024, 48 (3): 868-875.   DOI: 10.11720/wtyht.2024.1060
Abstract   HTML ( 1 )   PDF (1798KB)

China has accumulated massive data on total gamma radiation (γ) from the prolonged extensive surveys of uranium deposits. However, there is a marked lack of studies on radioactive environment assessment using these data. Based on the measurement principles of total gamma radiation and the absorbed dose rate in air, this study ascertained the relationships of the absorbed dose rate in air with the total natural gamma radiation and nuclide content and, accordingly, established the relationship between total gamma radiation and the absorbed dose rate in air. Furthermore, it analyzed the effects of instrument parameters on the measurement error, concluding that there existed a strictly linear relationship between the measured total gamma radiation and the absorbed dose rate in the air when bK/bU = 2.287 and bTh/bU = 0.430. Therefore, the bK/bU and bTh/bU ratios closer to both values correspond to more accurate absorbed dose rates in air converted from the measured total gamma radiation. Using the model of the Hunan Ionizing Radiation Measuring Station, this study calculated the coefficient for converting total gamma radiation into the absorbed dose rate in air, analyzed the error, and deduced the approximate uranium equivalent ranges of potassium and thorium in the instrument parameters. Furthermore, for the rock mass in Panjia Village, Guiyang County, Chenzhou City and the limestone area of Tuqiao Village in Yongxing County of the city, this study measured the total gamma radiation, gamma spectra, and absorbed dose rates in the air at the same stations. The results show that when the average nuclide content ratio CK/CU was less than 1 and CTh/CU ratio was less than 3, the absorbed dose rates in air estimated based on the total gamma radiation (measured using the FD3013 instrument) shared roughly the same error levels with those estimated based on energy spectra using the Beck formula, both yielding root mean square errors below 15%. As inferred from the average CK/CU and CTh/CU ratios of nuclides in China, the absorbed dose rate in air in most areas of China can be estimated using the total gamma radiation measured using an FD3013 instrument (or an instrument with similar performance). Overall, converting the total gamma radiation data from available extensive surveys of uranium deposits into effective absorbed dose rates in the air provides a methodological reference for rapid, large-area assessment of the external exposure level of natural radioactivity in the environment.

Figures and Tables | References | Related Articles | Metrics
Research on the detection of underground pedestrian passage by high precision gravity exploration
YANG Min, XU Xin-Qiang, CHEN Ming, Ji Xiao-Lin, WANG Wan-Yin, ZHAO Dong-Ming, ZHOU Wei, ZHANG Yi-Mi
Geophysical and Geochemical Exploration. 2024, 48 (3): 876-883.   DOI: 10.11720/wtyht.2024.0047
Abstract   HTML ( 3 )   PDF (3819KB)

Underground cavities with shallow burial and small scale are difficult to detect. With the development of gravity sensing technology, the accurate and rapid acquisition of micro-gravity variations brings new opportunities for detecting underground cavities, and it has wide research and practical value for the detection of small-scale underground cavities. This paper systematically analyzes and studies underground cavities from three aspects: gravity basic theory, gravity detection technology, and gravity data processing and inversion. Under given body size and gravity data accuracy, the maximum burial depth of gravity detection is calculated using the bisection method. High-density acquisition and high-precision gravity detection methods are applied to the actual detection of an underground pedestrian tunnel in a certain area of a passenger station. A set of high-precision gravity grid data is obtained. The theoretical research and measurement results indicate that existing gravity instruments have the ability to detect underground cavities. By using the minimum curvature potential field separation method, 2.5D interactive inversion and the target area recognition three-dimensional physical property fast inversion method, the approximate SN distribution and burial depth of the underground pedestrian tunnel are obtained, which is approximately 2.5~5 m, consistent with the actual situation. This study has developed a complete gravity exploration process for detecting underground cavities, and it has certain reference value.

Figures and Tables | References | Related Articles | Metrics
Application of the cross-borehole resistivity method in the monitoring of leakage for urban water supply pipelines
ZHANG Wei, ZHOU Yu-Kun, LIU Li-Yan, CHEN Jun-Liang
Geophysical and Geochemical Exploration. 2024, 48 (3): 884-890.   DOI: 10.11720/wtyht.2024.1368
Abstract   HTML ( 1 )   PDF (3195KB)

Urban main water supply pipelines are mostly buried along roads. Large pipe diameters and deep burial depths make it hard to detect their leakage in the early stage. Their leakage will severely influence urban traffic and residents' daily life. Hence, the leakage monitoring of water supply pipelines is particularly important. However, factors such as dense traffic lines, hardened road surfaces, and electromagnetic interference limit the application of the ground resistivity method and geological radars in pipeline monitoring. To make up for the shortcomings of existing monitoring methods, this study explored the cross-hole resistivity method for pipeline leakage monitoring. First of all, pipelines with and without leakage were simulated using forward modeling and inversion methods, analyzing the detection characteristics of the cross-borehole resistivity method. Then, electrode materials and burial methods were examined through experiments, solving the problems of electrode corrosion and weak electric field signals. Finally, an experimental site was set up near a water supply pipeline in Beijing, obtaining multi-phase monitoring data using the cross-borehole resistivity method. Through comparative analysis of multi-phase resistivity sections, this study analyzed the changes in pipeline leakage, delineating the leakage influence scope, which was verified by the leakage data from the waterworks. The satisfactory monitoring results suggest that the method proposed in this study can be referenced for similar pipeline leakage monitoring in cities.

Figures and Tables | References | Related Articles | Metrics
Please wait a minute...
For Selected: Toggle Thumbnails
More...
2024 Vol.48 No.2 No.1
2023 Vol.47 No.6 No.5 No.4 No.3 No.2 No.1
2022 Vol.46 No.6 No.5 No.4 No.3 No.2 No.1
2021 Vol.45 No.6 No.5 No.4 No.3 No.2 No.1
2020 Vol.44 No.6 No.5 No.4 No.3 No.2 No.1
2019 Vol.43 No.6 No.5 No.4 No.3 No.2 No.1
2018 Vol.42 No.6 No.5 No.4 No.3 No.2 No.1
2017 Vol.41 No.6 No.5 No.4 No.3 No.2 No.1
2016 Vol.40 No.6 No.5 No.4 No.3 No.2 No.1
2015 Vol.39 No.S1 No.6 No.5 No.4 No.3 No.2
No.1
2014 Vol.38 No.6 No.5 No.4 No.3 No.2 No.1
2013 Vol.37 No.6 No.5 No.4 No.3 No.2 No.1
2012 Vol.36 No.6 No.S1 No.5 No.4 No.3 No.2
No.1
2011 Vol.35 No.6 No.5 No.4 No.3 No.2 No.1
2010 Vol.34 No.6 No.5 No.4 No.3 No.2 No.1
2009 Vol.33 No.6 No.5 No.4 No.3 No.2 No.1
2008 Vol.32 No.6 No.5 No.4 No.3 No.2 No.1
2007 Vol.31 No.6 No.5 No.4 No.3 No.2 No.1
2006 Vol.30 No.6 No.5 No.4 No.3 No.2 No.1
2005 Vol.29 No.6 No.5 No.4 No.3 No.2 No.1
2004 Vol.28 No.6 No.5 No.4 No.3 No.2 No.1
2003 Vol.27 No.6 No.5 No.4 No.3 No.2 No.1
2002 Vol.26 No.6 No.5 No.4 No.3 No.2 No.1
2001 Vol.25 No.6 No.5 No.4 No.3 No.2 No.1
2000 Vol.24 No.6 No.5 No.4 No.3 No.2 No.1
1999 Vol.23 No.6 No.5 No.4 No.3 No.2 No.1
1998 Vol.22 No.6 No.5 No.4 No.3 No.2 No.1
1997 Vol.21 No.6 No.5 No.4 No.3 No.2 No.1
1996 Vol.20 No.6 No.5 No.4 No.3 No.2 No.1
1995 Vol.19 No.6 No.5 No.4 No.3 No.2 No.1
1994 Vol.18 No.6 No.5 No.4 No.3 No.2 No.1
1993 Vol.17 No.6 No.5 No.4 No.3 No.2 No.1
1992 Vol.16 No.6 No.5 No.4 No.3 No.2 No.1
1991 Vol.15 No.6 No.5 No.4 No.3 No.2 No.1
1990 Vol.14 No.6 No.5 No.4 No.3 No.2 No.1
1989 Vol.13 No.6 No.5 No.4 No.3 No.2 No.1
1988 Vol.12 No.6 No.5 No.4 No.3 No.2 No.1
1987 Vol.11 No.6 No.5 No.4 No.3 No.2 No.1
1986 Vol.10 No.6 No.5 No.4
1986 Vol.6 No.4
1986 Vol.10 No.3 No.2 No.1
1985 Vol.9 No.6 No.5 No.4 No.3 No.2 No.1
1984 Vol.8 No.6 No.5 No.4 No.3 No.2 No.1
1983 Vol.7 No.6 No.5 No.4 No.3 No.2 No.1
1982 Vol.6 No.6 No.5 No.4 No.3 No.2 No.1
1981 Vol.5 No.6 No.5 No.4 No.3 No.2 No.1
1980 Vol.4 No.6 No.5 No.4 No.3 No.2 No.1
1979 Vol.3 No.6 No.5 No.4 No.3 No.2 No.1
Please wait a minute...
For Selected: Toggle Thumbnails
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.  
Abstract2646)      PDF (4180KB)(4926)      


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.

Related Articles | Metrics
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
Abstract1361)   HTML151)    PDF (12833KB)(4317)      

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.

Reference | Related Articles | Metrics
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
Abstract799)   HTML408)    PDF (4078KB)(3872)      

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.

Table and Figures | Reference | Related Articles | Metrics
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.  
Abstract3385)      PDF (431KB)(3549)      

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.

Related Articles | Metrics
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.  
Abstract2966)      PDF (1014KB)(3440)      

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.

Related Articles | Metrics
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.  
Abstract6784)      PDF (532KB)(3151)      

 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.

Related Articles | Metrics
THE UTILIZATION OF EXCEL TO THE PERFORMANCE OF R-MODE CLUSTER ANALYSIS
CHUN Nei-ya
Geophysical and Geochemical Exploration    2007, 31 (4): 374-376.  
Abstract4642)      PDF (659KB)(2713)      

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.

Reference | Related Articles | Metrics
CALCULATION OF THE ANOMALY AREA
Zhao Rongjun
Geophysical and Geochemical Exploration    2000, 24 (2): 154-156.  
Abstract1586)      PDF (346KB)(2691)      

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.

Reference | Related Articles | Metrics
THE CHOICE OF GRIDDING METHODS FOR GEOPHYSICAL DATA
LIU Zhao-Ping, YANG Jin, WU Wei
Geophysical and Geochemical Exploration    2010, 34 (1): 93-97.  
Abstract3172)      PDF (1939KB)(2654)      

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.

Related Articles | Metrics
THE APPLICATION OF ATOM INTERFEROMETER TO THE MEASUREMENT OF GRAVITATIONAL ACCELERATION
ZHANG Chang-da
Geophysical and Geochemical Exploration    2000, 24 (5): 321-326.  
Abstract1750)      PDF (673KB)(2566)      

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.

Reference | Related Articles | Metrics
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
Abstract2359)      PDF (964KB)(2549)      
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.
Reference | Related Articles | Metrics
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.  
Abstract3053)      PDF (2969KB)(2425)      

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.

Reference | Related Articles | Metrics
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.  
Abstract4313)      PDF (403KB)(2402)      

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.

Related Articles | Metrics
RECENT ADVANCES IN THE RESEARCH AND DEVELOPMENT OF QUANTUM MAGNETOMETERS
ZHANG Chang-da
Geophysical and Geochemical Exploration    2005, 29 (4): 283-287.  
Abstract1752)      PDF (376KB)(2399)      

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

Reference | Related Articles | Metrics
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.  
Abstract3751)      PDF (534KB)(2351)      

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.

Reference | Related Articles | Metrics
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.  
Abstract3752)      PDF (643KB)(2290)      

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.

Reference | Related Articles | Metrics
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
Abstract644)   HTML3)    PDF (3147KB)(2246)      

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.

Table and Figures | Reference | Related Articles | Metrics
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.  
Abstract3078)      PDF (2717KB)(2240)      

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.

Related Articles | Metrics
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.  
Abstract3737)      PDF (363KB)(2229)      

 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.

Related Articles | Metrics
PARAMETER SELECTION IN VIBROSEIS SEISMIC EXPLORATION
XUE Hai-Fei, DONG Shou-Hua, TAO Wen-Peng
Geophysical and Geochemical Exploration    2010, 34 (2): 185-190.  
Abstract3504)      PDF (3477KB)(2221)      

 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.

Related Articles | Metrics
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.  
Abstract2629)      PDF (2180KB)(2188)      

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.

Reference | Related Articles | Metrics
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.  
Abstract3571)      PDF (572KB)(2173)      

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.

Related Articles | Metrics
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.  
Abstract2828)      PDF (1927KB)(2151)      

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.

Related Articles | Metrics
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.  
Abstract3653)      PDF (830KB)(2144)      

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.

Related Articles | Metrics
THE INVERSED PROBLEM IN GRAVITY AND MAGNETICEXPLORATION: A REVIEW
Zeng Hualin
Geophysical and Geochemical Exploration    1990, 14 (3): 182-190.  
Abstract2047)      PDF (737KB)(2113)      

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.

Related Articles | Metrics
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
Abstract5032)      PDF (1427KB)(2104)      
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.
Reference | Related Articles | Metrics
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.  
Abstract3181)      PDF (1060KB)(2097)      

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.

Related Articles | Metrics
Geophysical and Geochemical Exploration    1982, 6 (3): 154-156.  
Abstract1180)      PDF (190KB)(2058)      
Reference | Related Articles | Metrics
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.  
Abstract2206)      PDF (690KB)(2033)      

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.

Reference | Related Articles | Metrics
SOME PROBLEMS CONCERNING THE CONVERSIONOF MAPS BETWEEN SURFER AND MAPGIS
QIN Lin-Jiang
Geophysical and Geochemical Exploration    2010, 34 (5): 677-680.  
Abstract5489)      PDF (865KB)(2016)      

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.

Related Articles | Metrics
PML ABSORBING BOUNDARY CONDITION FORNUMERICAL MODELING OF RAYLEIGH WAVE
XIONG Zhang-Qiang, TANG Sheng-Song, ZHANG Da-Zhou
Geophysical and Geochemical Exploration    2009, 33 (4): 453-457.  
Abstract3450)      PDF (2025KB)(2014)      

The algorithm of the finite difference oforder velocitystress staggered grids has been built, which is

suitable for the perfectly matched layer (PML) absorbing boundary for elastic media. Meanwhile, the construction of the

PML absorbing boundary condition and the realization of the finitedifference algorithm are discussed in detail. Wave

field modeling calculations show that, compared with the conventional decaying exponential absorbing boundary and non

absorbing boundary, the PML absorbing boundary can perform absorption much more clearly and absorb the boundary

reflection from various angles, whose absorptivity (the ratio of absorption energy to unabsorbable energy) can reach

99.99%. The PML absorbing boundary can well eliminate the periodic folding effects, which makes the calculation of the

wave field characteristics very distinct, and the Rayleigh wave can be clearly shown in the waveform record.

Related Articles | Metrics
YANG Li-De
Geophysical and Geochemical Exploration    2009, 33 (6): 741-742.  
Abstract2213)      PDF (240KB)(1999)      
Related Articles | Metrics
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.  
Abstract3232)      PDF (1351KB)(1988)      

 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.

Related Articles | Metrics
THE COMPARATIVE STUDY AND APPLICATION OF SEVERALTIMEFREQUENCY ANALYSIS METHODS IN THE COAL FIELD
HU Ming-Shun, PAN Dong-Ming, XU Hong-Li, ZHAO Li-Gui
Geophysical and Geochemical Exploration    2009, 33 (6): 691-695.  
Abstract2505)      PDF (2110KB)(1972)      

In the light of the characteristic time-frequency properties of different time-frequency analysis methods, it is

important to select an optimal time-frequency analysis method for high precision seismic exploration in the coal field on the

basis of comparing and studying these methods. Aimed at probing into STFT, Wavelet Transform, S-Transform, Choi-Williams

Distribution, Wigner-Ville Distribution and its improved methods, this paper studied advantages and disadvantages of every method

through numerical simulation in time resolution, frequency resolution and interference. The First Break Picking and Separate

Frequency Display for Collapse Column interpretation were realized by SPWVD and S-Transform, with a good result obtained.

Related Articles | Metrics
The application of the integrated geophysical-geochemical method to the Yiliu polymetallic ore district in northern Guangdong Province
WU Wei-Guo
Geophysical and Geochemical Exploration    2015, 39 (6): 1097-1103.   DOI: 10.11720/wtyht.2015.6.01
Abstract1139)   HTML152)    PDF (11771KB)(1944)      

The main minerals in the Yiliu polymetallic ore district are mainly As, Sb, Pb, Zn, Ag, W, Sn, Nb and Ta, the deposit types and the ore-controlling factors are complex and diverse. Recently, by using 1:50000 geochemical stream sediment survey, geochemical soil survey and CSAMT method in this ore district, supergene distribution of elements were found, and many integrated anomalies were delineated. A comprehensive evaluation of all kinds of anomalies shows that the F3 fault has features of ore-passage structure and ore-storage structure, and the area sandwiched between F2 and F3 fault are favorable ore-forming place, whereas the depression parts of biotite granite which have high resistance and multiple sets of fracture intersections are most favorable places for mineralization.

Reference | Related Articles | Metrics
A TENTATIVE DISCUSSION ON THE RESOLUTION OF THE GROUND-PENETRATING RADAR
YUAN Ming-de
Geophysical and Geochemical Exploration    2003, 27 (1): 28-32.  
Abstract2530)      PDF (512KB)(1940)      

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.

Reference | Related Articles | Metrics
PRESENT STATE AND REVIVAL OF GRAVITY GRADIOMETRY
Zeng Hualin
Geophysical and Geochemical Exploration    1999, 23 (1): 1-6.  
Abstract2259)      PDF (474KB)(1919)      

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.

Reference | Related Articles | Metrics
THE APPLICATION OF THE RAYLEIGH SURFACE WAVE TECHNIQUE TO RAILWAYS
LI Hai
Geophysical and Geochemical Exploration    2002, 26 (2): 160-162.  
Abstract1913)      PDF (480KB)(1905)      

With practical examples, this paper deals with the basic principle and technique of the Rayleigh surface wave exploration, the technology for its application to railways, the data acquisition, processing and interpretation, and the calculation method for converting the velocity of the Rayleigh surface wave to the bearing capacity. The reliability of applying this technique to railways is also pointed out.

Reference | Related Articles | Metrics
THE EXPLORATION EFFICIENCY OF THE TERRATEM ELECTROMAGNETIC SYSTEM,IN THE CONCEAL IRON DEPOSIT,HENAN PROVINCE
LI Shui-Peng, ZHANG Tong-Zhong, JING Jin-Ming
Geophysical and Geochemical Exploration    2009, 33 (4): 424-426.  
Abstract2781)      PDF (608KB)(1900)      

This thesis supply a profile about performance of TerraTEM system and the  distinguishing feature of TEM. By exploring

work on two conceal iron deposit in HeNan province and analyzing. the abnormal value of the TEM system.combining with drill

drawing,The writer prove that the TEM can take a obvious effect on exploring iron mineral.

Related Articles | Metrics
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.  
Abstract2122)      PDF (749KB)(1899)      

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.

Reference | Related Articles | Metrics
More...
Please wait a minute...
For Selected: Toggle Thumbnails
Distribution of microorganisms in the typical geothermal field environment and its significance for geothermal exploration
ZHENG Xu-Ying, XU Ke-Wei, GU Lei, WANG Guo-Jian, LI Guang-Zhi, GUO Jia-Qi, ZOU Yu, BORJIGIN Tenger
Geophysical and Geochemical Exploration    2023, 47 (5): 1127-1136.   DOI: 10.11720/wtyht.2023.1151
Abstract287)   HTML17)    PDF (4903KB)(258)      

As a kind of clean energy, geothermal energy has attracted the attention of scholars all over the world in recent years. Previous geochemical exploration methods for geothermal resources are limited to the analysis of individual geochemical indices. Moreover, previous studies of microorganisms in geothermal fields mostly focus on hot spring outcrops, lacking ecological studies of geothermal resources in complex terrains. This study investigated the soil geochemistry and microbial diversity of the Bantang Hot Spring geothermal field in Chaohu, Anhui Province. Geochemical indices such as head-space gas, soil gas, acid-hydrolyzed hydrocarbons, and altered carbonate were detected in this study. Combined with the microbial high-throughput sequencing technology, this study analyzed the composition and spatial-temporal distribution of the microbial population above the geothermal fields in uplifted mountains and the relationship between these bioinformatics characteristics and the geochemical indices. The results indicate that the acid-hydrolyzed hydrocarbons on the surface of the geothermal field showed a maximum methane concentration of 43.7 μL/kg in the area between faults F2 and F3, adequately reflecting the fault location of the geothermal field.Bacillaceae, Hydrogenophilaceae, and Thermodesulfovibrionaceae in the geothermal field and the background area showed large relative abundance differences, which were 0.178%, 0.108%, and 0.060%, respectively. This result indicates that they are sensitive to geothermal resources and correspond well to geochemical indices above the known geothermal field. This study preliminarily investigated the diversity of geothermal microorganisms in the geothermal field and analyzed the corresponding relationships between microbial distribution characteristics and geochemical indexes, providing technical support for the microbiological exploration of geothermal resources.

Table and Figures | Reference | Related Articles | Metrics
Advancements in research on geochemical exploration methods and technologies for mineral resources in overburden areas
SUN Yue, ZHANG Zhen-Yu, FENG Bin, YANG Shao-Ping, WANG Zhi-Feng
Geophysical and Geochemical Exploration    2023, 47 (6): 1387-1399.   DOI: 10.11720/wtyht.2023.0109
Abstract229)   HTML15)    PDF (2899KB)(323)      

Following China's planning for ore prospecting in overburden areas, China's geochemical exploration researchers have conducted extensive research on the fundamental theories, methods, and technologies of geochemical exploration for overburden areas in the past decade. They achieved significant advances mainly in two aspects: (1) the research on the migration mechanism, occurrence state, and anomaly formation mechanism of elements in overburden areas; (2) advances in methods and technologies, including geoelectrochemistry, active state of elements, geogas, separation of micro-fine-sized soil particles, soil thermomagnetic composition, and integrated gas survey, as well as numerous experimental demonstrations. These advances represent continuous progress in the research on the fundamental theories, methods, and technologies of geochemical exploration for overburden areas, providing new geochemical methods and technologies for ore prospecting breakthroughs in overburden areas.

Table and Figures | Reference | Related Articles | Metrics
Aerogeophysical anomalies and prospecting direction in the Fengtai ore concentration area
XU Xue-Yi, XIONG Sheng-Qing, YANG Xue, GAO Wei-Hong, FAN Zheng-Guo, JIA Zhi-Ye
Geophysical and Geochemical Exploration    2023, 47 (5): 1157-1168.   DOI: 10.11720/wtyht.2023.0068
Abstract224)   HTML10)    PDF (14675KB)(286)      

The Fengtai ore concentration area is an important producing area of plumbum-zinc and gold ores in the middle of the Qinling orogenic belt. It hosts many large to super-large deposits, such as Qiandongshan-Dongtangzi, Bafangshan-Erlihe, Baguamiao, and Shuangwang deposits. With the exploitation proceeding, the reserves of these deposits have decreased significantly, and the ore prospecting in these deposits has shifted from the surface to the deep part. However, the geophysical fields in the deposits are yet to be ascertained, severely restricting research on the metallogenic regularity of the deposits and the ore prospecting and exploration in the peripheral zones. Based on the latest 1∶50,000 aeromagnetic and airborne radioactivity survey data, as well as gravity data, this study investigated the multi-source geophysical fields on the scales of the region, the ore concentration area, and deposits, aiming to summarize the distribution patterns of geophysical anomalies of different scales and provide evidence for research on metallogenic regularity and prospecting prediction. The results show that the Fengtai and the Xicheng ore concentration areas, with similar magnetic structures, are separated by the zone with strong magnetic anomalies caused by the crystalline basement of the Huicheng Basin. The first vertical derivative of gravity reveals that the Fengtai and Xicheng ore concentration areas have density structures similar to the Huicheng Basin. It can be inferred that the shallow part is a unified basin and that a large prospecting space exists between the two ore concentration areas. Many NW-trending linear magnetic anomaly zones occur in the Fengtai ore concentration area. Their locations are highly consistent with those of fault structures, and they were offset by NE-trending structures due to late transformation. The second vertical derivative of gravity reveals that many intermediate-acid intrusive stocks or veins have developed in the deep part of the Fengtai ore concentration area. Structural boundaries can be effectively identified based on the first vertical derivative, X-directional derivative, and wavelet transform of aeromagnetic data. Furthermore, ore bodies are mostly distributed in the NW direction along the tectonic belt. All these will play an important role in guiding ore prospecting and exploration in the Fengtai ore concentration area.

Table and Figures | Reference | Related Articles | Metrics
Gravity survey and audio magnetotellurics-based insights into the deep structures and geothermal resource potential of the Rucheng Basin
ZHAO Bao-Feng, WANG Qi-Nian, GUO Xin, GUAN Da-Wei, CHEN Tong-Gang, FANG Wen
Geophysical and Geochemical Exploration    2023, 47 (5): 1147-1156.   DOI: 10.11720/wtyht.2023.1449
Abstract210)   HTML8)    PDF (8018KB)(335)      

Geothermal resources are significant clean energy and tourism mineral resources. The Rucheng Basin, a carbonate basin in the southeastern mountainous area of Hunan Province, possesses favorable conditions for the formation of convective geothermal energy. However, the basin is enclosed on three sides by the giant Zhuguangshan rock mass, and its basement is subjected to the intrusion and destruction by the rock mass, resulting in severely deformed formations, crisscrossing faults, and significantly different eastern and western structures. The understanding of the basin's water- and heat-conducting pathways and deep reservoir structures remains elusive, thus restricting the investigation of the basin's geothermal potential. Hence, this study probed the basin's deep structures through gravity survey and audio magnetotellurics (AMT), obtaining the following insights: (1) The Rucheng Basin has developed into a bidirectional ramp structure due to east-west differentiation. The synclinorium in the east experienced compression and clockwise rotation due to the emplacement of the Yanshanian rock mass, rocks were fragmented in the core zone, and strike-slip fracture zones were found at the boundary. The faults have vertical cutting depths exceeding 4 km, widths ranging from 300~600 m, and dip angles between 80°~90°. (2) The basin's basement anticlinal axis hosts several NWW-directed concealed rock masses, with diameters from 3~4 km and buried depths from 0.5~1.5 km. Hot springs reside in the fracture zones crossing the boundaries of the concealed rock masses. (3) The basin boasts favorable conditions for the formation of convective geothermal energy. Folds, fault zones, and concealed rock masses match each other to form a unified spatial combination of heat-controlling elements, manifesting heat accumulation characterized by east-west recharge and intermediate discharge. With more thriving deep geothermal reservoirs in the east, the basin has high potential for geothermal resources.

Table and Figures | Reference | Related Articles | Metrics
An experimental investigation of the CO2 and SO2 gas geochemical survey method for mineral exploration in forested areas
WAN Wei, WANG Ming-Qi, CHENG Zhi-Zhong, FAN Hui-Hu, ZUO Li-Bo, LI Jun-Hui
Geophysical and Geochemical Exploration    2023, 47 (5): 1137-1146.   DOI: 10.11720/wtyht.2023.1615
Abstract204)   HTML9)    PDF (4627KB)(174)      

This study aims to explore the feasibility of the carbon dioxide (CO2) and sulfur dioxide (SO2) gas geochemical survey method for mineral exploration in forested areas. Based on the newly designed gas rapid analysis instrument, this study conducted an experimental investigation of the method in the forested Jiapigou gold concentration area, Jilin Province. The results show that significant CO2 and SO2 anomalies were observed above the concealed ore bodies and structures. In the forested area, the CO2 and SO2 gas geochemical survey method reflected the fault structures and effectively indicated the deep concealed gold deposit. This method holds critical significance for the breakthrough of prospecting technology in China's covered areas.

Table and Figures | Reference | Related Articles | Metrics
Application of the opposing-coils transient electromagnetic method in urban geological surveys
HE Sheng, WANG Wan-Ping, DONG Gao-Feng, NAN Xiu-Jia, WEI Feng-Feng, BAI Yong-Yong
Geophysical and Geochemical Exploration    2023, 47 (5): 1379-1386.   DOI: 10.11720/wtyht.2023.1554
Abstract189)   HTML4)    PDF (5856KB)(320)      

With the rapid development of urban infrastructure,the demand for urban geological work is increasing,and urban geological surveys become particularly important.Urban geophysical exploration has different exploration purposes and working environments from conventional geophysical exploration.Accordingly,compared with conventional geophysical exploration methods,the geophysical exploration methods for urban geological surveys face the challenges of many interference factors,limited construction sites and time,and high requirements for exploration accuracy.The opposing-coils transient electromagnetic(OCTEM) method enjoys a strong anti-interference ability,convenient and efficient construction,and high resolution.Therefore,this study employed the OCTEM method to investigate the test profile in the urban geological survey and evaluation of Haidong City.This test profile was subjected to numerous interference sources since it crossed 11 highways and railways and passed through factories,schools,logistics parks,villages,living quarters,and rivers.Consequently,the OCTEM results agree well with the results of single-point resistivity sounding and drilling results.Therefore,the OCTEM method proposed in this study is effective for urban geological surveys.

Table and Figures | Reference | Related Articles | Metrics
Application of integrated geophysical exploration technology in the geothermal exploration of northern Jinan
ZHANG Yi, LIU Peng-Lei, WANG Yu-Min, ZHANG Peng-Peng, ZHANG Chao, ZHANG Ning
Geophysical and Geochemical Exploration    2024, 48 (1): 58-66.   DOI: 10.11720/wtyht.2024.1141
Abstract185)   HTML9)    PDF (8896KB)(317)      

Ji'nan possesses highly abundant geothermal resources, which are hosted by Ordovician-Cambrian karst-fissured geothermal reservoirs and Neogene-Paleogene clastic pore-fissure geothermal reservoirs. The geothermal exploration in this study focuses on the Ordovician-Cambrian karst fissured geothermal reservoirs in Daqiao Town in northern Ji'nan. Through geophysical profile measurements, this study aims to identify the distributions of strata and fault structures and the burial depths of geothermal reservoirs, infer the attitudes and spatial morphologies of fault structures associated with heat control and conduction, delineate the target area for geothermal well construction, and conduct drilling verification in the favorable underground water-rich position. Building on the collected data, this study interpreted and inferred the fault structures in the study area and comparatively analyzed the water-bearing properties by employing direct-current sounding, controlled source audio magnetotellurics, and magnetotelluric survey. A geothermal exploration and production combined well was constructed in a favorable position of the geothermal target area, manifesting a completion depth of 1 532.06 m, a static-water burial depth of 13.03 m, a wellhead water temperature of 50.1 ℃, a water yield of 132.998 m3/h, and a dropdown depth of 18.27 m.

Table and Figures | Reference | Related Articles | Metrics
Regional geochemical characteristics and metallogenic prospect area prediction of strategic mineral antimony in the Eerguna block, Heilongjiang Province, China
WAN Tai-Ping, ZHANG Li, LIU Han-Liang
Geophysical and Geochemical Exploration    2023, 47 (5): 1179-1188.   DOI: 10.11720/wtyht.2023.1439
Abstract182)   HTML4)    PDF (4012KB)(170)      

The Eerguna block with metallogenic geological conditions is an important metallogenic area in Heilongjiang Province. Globally, China boasts the richest resource of antimony. However, the high mining intensity in recent years imposes huge challenges to this resource advantage of China. In this context, it is necessary to ascertain the geochemical characteristics of antimony in the Eerguna block. Based on the data of the 1∶250 000 stream sediment survey in the Eerguna block, this study explored the geochemical parameters of antimony in different tectonic units and the regional geochemical anomalies of this block. The results show that the study area has median and average concentrations of antimony of 0.33×10-6 and 0.55×10-6, respectively. The Mohe foreland basin is rich in antimony, with median and average concentrations of antimony higher than those of the study area. Furthermore, zones with high and extremely high antimony concentrations in the study area are distributed primarily in the Mohe foreland basin. Based on the 85% cumulative percentage, this study determined 66 geochemical anomalies of antimony, among which two reach the scale of geochemical provinces. Furthermore, this study identified significant geochemical anomalies of antimony in the discovered gold, antimony, and plumbum deposits or ore occurrences (mineralization points). Based on the spatial distributions of geochemical anomalies and metallogenic geological conditions of antimony, arsenic, and gold, this study delineated three metallogenic prospect areas of antimony: the Beijicun-Sanlianshan metallogenic prospect area, the Wangsushan-Daling metallogenic prospect area, and the Baikalushan-Huzhong metallogenic prospect area. In addition, the geochemical anomalies and metallogenic prospect areas for antimony, arsenic, and gold provide important areas for searching for sulfide deposits such as gold, antimony, and plumbum ones in the study area.

Table and Figures | Reference | Related Articles | Metrics
Predicting the geothermal resources of the Tangyu geothermal field in Meixian County, Shaanxi Province, based on soil radon measurement and the controlled source audio magnetotelluric method
XUE Dong-Xu, LIU Cheng, GUO Fa, WANG Jun, XU Duo-Xun, YANG Sheng-Fei, ZHANG Pei
Geophysical and Geochemical Exploration    2023, 47 (5): 1169-1178.   DOI: 10.11720/wtyht.2023.0010
Abstract181)   HTML10)    PDF (4345KB)(304)      

Despite abundant geothermal reserves of the Tangyu geothermal field in Meixian County, Shaanxi Province, long-term exploitation has decreased the water temperatures and yields of its existing geothermal wells year by year. Hence, there is an urgent need to explore new potential geothermal resources in the geothermal field. Since the known geothermal wells in the geothermal field are significantly controlled by faults, investigating the deep fault propagation holds critical significance for exploring the geothermal field’s potential geothermal resources. Due to the method limitations and the topographic influence, identifying thermal control faults through conventional geological route investigation or large-scale engineering is not applicable to the geothermal field. Therefore, a new technical method combining the penetrating soil radon measurement and the controlled source audio magnetotelluric (CSAMT) method was employed in this study to find concealed faults and delineate potential geothermal areas. Based on the measured surface soil radon concentration anomaly data and the subsurface electrical structure model derived from the CSAMT data inversion, this study inferred six new concealed faults on the basis of corroborating the known faults, predicted two potential geothermal areas, and built a conceptual model for the Tangyu geothermal field. As revealed by the results, the soil radon concentrations at concealed faults are much higher than the regional background value, and the concealed faults are located in the low-resistivity fracture zones as indicated by the apparent resistivity results based on CSAMT data inversion. Besides, the two potential geothermal areas spread from 450~750 m and 850~1 150 m on the profile, respectively, at depths of approximately 250~300 m. This study concludes that the geothermal field resides in a low-resistivity region with soil radon anomalies three times the regional background value. The results of this study provide a reference for the subsequent sustainable production and utilization of potential geothermal resources in the region.

Table and Figures | Reference | Related Articles | Metrics
Comparison and summary of different azimuthal anisotropy-based inversion techniques
LIANG Zhi-Qiang, LI Hong
Geophysical and Geochemical Exploration    2024, 48 (2): 443-450.   DOI: 10.11720/wtyht.2024.1251
Abstract181)   HTML2)    PDF (3440KB)(118)      

The progress in seismic acquisition techniques characterized by wide azimuths,wide frequency bands,and high densities has greatly promoted the application of the prestack P-wave fracture inversion technique based on the azimuthal anisotropy theory.Azimuthal anisotropy-based inversion can yield the azimuths and intensities of fractures.However,different inversion techniques yield different parameters for fracture intensity characterization,resulting in inconsistent inversion results.Consequently,the azimuthal anisotropy-based inversion results of fractures are non-unique,leading to confusion about accurate results.Based on the Thomsen anisotropy theory,as well as the interrelationships between fracture models(the Hudson coin model and the Schoenberg linear sliding model),this study established the connections of anisotropic parameters between different fracture inversion techniques(VVAZ,Ruger's approximation,and Fourier series),presenting the real meanings and mathematical expressions of results from different azimuthal anisotropy-based fracture inversion techniques.Additionally,this study summarized the relationships of parameters between different inversion techniques and fracture models,further deepening the research on azimuthal anisotropy-based fracture inversion.This study lays solid theoretical and technical foundations for large-scale fracture detection based on the seismic data obtained using the seismic acquisition techniques featuring wide azimuths,wide frequency bands, and high densities.

Table and Figures | Reference | Related Articles | Metrics
Prospecting for concealed skarn iron deposits using the high-precision gravity-magnetic survey method
DONG Jian, LI Xiao-Peng, FU Chao, DANG Zhi-Cai, ZHAO Xiao-Bo, ZENG Qing-Bin, HU Xue-Ping, WANG Jin-Hui
Geophysical and Geochemical Exploration    2024, 48 (1): 31-39.   DOI: 10.11720/wtyht.2024.1047
Abstract175)   HTML7)    PDF (7885KB)(276)      

The Laiwu area in central Shandong Province, situated in the eastern North China Craton, is a significant production area of skarn iron-rich ores. Its ore deposits occur primarily in the contact zone between the mining rock mass and the Middle Ordovician carbonate formation. Based on the latest areal gravity and magnetic survey results, this study thoroughly investigated the characteristics of gravity and magnetic anomalies along the Shijiaquan-Liujiamiao area in the western periphery of the mine rock mass. Then, this study delineated the deep prospecting target combining the characteristics of gravity and magnetic fields of the known iron deposits in the Laiwu area. Large-scale gravity and magnetic profiles were arranged in the favorable mineralization area. With the known boreholes as constraints, the gravity and magnetic anomalies were qualitatively and quantitatively interpreted using the 2.5D gravity-magnetic joint inversion technique. The interpretation results provide a basis for the location and depth of the borehole to be placed, which revealed a 15.8 m-thick iron-rich ore deposit, suggesting remarkable prospecting effects. This study holds critical indicative significance for further exploration of skarn iron ore deposits in this area.

Table and Figures | Reference | Related Articles | Metrics
A review of thirty years of airborne geophysical surveys in the Qiangtang Basin and future prospect
ZHOU Dao-Qing, XIONG Sheng-Qing, WANG Bao-Di, CAO Bao-Bao, GUO Zhi-Hong, HU Yue, ZHENG Yu-Zhou, ZHAO Rui, WEI Yan-Yan, XIAO Meng-Chu, HU Xia-Wei, YAN Qiao-Juan
Geophysical and Geochemical Exploration    2024, 48 (2): 287-295.   DOI: 10.11720/wtyht.2024.1413
Abstract173)   HTML14)    PDF (7354KB)(191)      

Airborne geophysical surveys, characteristic of being green, economical, efficient, and subjected to less influence by surface factors, serve as the one of most effective means of basic surveys and scientific research on the Qinghai-Tibet Plateau. This study reviewed the progress in the airborne geophysical surveys in the Qiangtang Basin of the Qinghai-Tibet Plateau in the past thirty years, systematically summarizing the progress and geological interpretation results of comprehensive airborne geophysical surveys in the basin. Furthermore, this study presented research progress and understanding of major basic geological issues of the basin, such as the basin's boundaries, central uplift zone, basement properties, deep structures, and cover characteristics, as well as the identification of favorable structural areas for oil and gas exploration. Finally, based on an analysis of the developmental trends of airborne geophysical surveys in the Qiangtang Basin, this study proposed opinions and suggestions for key research directions in the future.

Table and Figures | Reference | Related Articles | Metrics
Chronology and geochemical characteristics of trachytes in the Tiaojishan Formation, Xuanhua Basin, northwestern Hebei Province, and their geological implications
YANG Ji-Yuan, HU Xin-Zhuo, ZHOU Jing, QI Peng-Chao, LI Ze-Yang, MENG Jia-Bao, XU Fan, ZHANG Hui-Bin, QI Hui-Yun
Geophysical and Geochemical Exploration    2024, 48 (1): 1-14.   DOI: 10.11720/wtyht.2024.2503
Abstract171)   HTML13)    PDF (8237KB)(160)      

The Tiaojishan Formation in northwestern Hebei Province is home to volcanic-sedimentary strata. Due to the lack of fossil organisms, insufficient isotopic dating data, and outdated dating methods, the formation epochs of these strata have been controversial. To accurately determine their formation epochs and examine their regional geotectonic setting, this study conducted a detailed field investigation of the lithologic assemblage of the Tiaojishan Formation in the Xuanhua Basin. Petrological, petrogeochemical, and high-precision isotopic dating studies were conducted on the trachytic volcanic rocks in the upper segment of the formation, obtaining the LA-ICP-MS-based zircon U-Pb isotopic ages, which were 161.1±1.2 Ma and 162.5±1.3Ma. As indicated by the petrological and petrogeochemical characteristics, these trachytic volcanic rocks belong to the shoshonite series, exhibiting enriched light rare earth elements, relatively enriched elements including Rb, K, Th, Ce, Zr, and Hf, and relatively depleted Ba, Nb, Sr, P, and Ti. According to the comparison of principal parameters and graphical discrimination, the magma originated primarily from the melting of continental crustal materials and formed in the tectonic setting of compressional continental margin volcanic arcs. The comprehensive research reveals that the Tiaojishan Formation formed primarily during the Middle Jurassic and continued to the Late Jurassic, and the trachytic volcanic rocks in its upper segment formed in the intraplate compressional tectonic setting. The results of this study provide new data for the division and correlation of Mesozoic volcanic-sedimentary strata and the analysis of their formation environment.

Table and Figures | Reference | Related Articles | Metrics
Application of the geochemical block method to the assessment of copper resources in Ethiopia
XIANG Wen-Shuai, BAI Yang, JIANG Jun-Sheng, LEI Yi-Jun, HUNDIE Melka, SISAY Degu, ZHANG Yuan-Pei, WU Ying, ZHENG Xiong-Wei
Geophysical and Geochemical Exploration    2023, 47 (4): 845-855.   DOI: 10.11720/wtyht.2023.1198
Abstract170)   HTML5)    PDF (6040KB)(177)      

Low-density geochemical mapping is characterized by high order streams to be sampled and a large coverage area and can be used to effectively trace geochemical blocks with high metal contents. Based on the 1:1,000,000 low-density geochemical mapping data of Ethiopia and the processing of the testing data of Cu in the original stream sediments, this study calculated the anomaly threshold of Cu at 37×10-6 through iterative deletion. Then, this study delineated three geochemical blocks and two regional anomalies with 37×10-6, 42×10-6, 47×10-6, 52×10-6, 59×10-6, and 66×10-6 as grading intervals. It calculated the mineralization coefficient of Cu ore bodies in the study area at 0.055% by referencing the known reserves of Cu deposits in geochemical blocks with a high level of copper exploration in the same metallogenic belt. Moreover, this study estimated the Cu resources in the study area at 2,600,000 t based on a rock mass thickness of 1,000 m. By combining the analysis of metallogenic geological conditions, this study determined that the zones where geochemical blocks nos. 2, 3, and 4 are located can be considered key metallogenic prospect areas for further detailed exploration.

Table and Figures | Reference | Related Articles | Metrics
First-arrival wave travel time-based tomography inversion with surface wave information as constraints
ZHANG Li-Zhen, SUN Cheng-Yu, WANG Zhi-Nong, LI Shi-Zhong, JIAO Jun-Feng, YAN Ting-Rong
Geophysical and Geochemical Exploration    2023, 47 (5): 1198-1205.   DOI: 10.11720/wtyht.2023.1536
Abstract163)   HTML2)    PDF (4925KB)(214)      

The performance of ray-based tomography inversion is affected by many factors,such as initial model error and low-velocity interlayer.The conventional tomography method based on first-arrival wave travel time,which constrains or smooths models,destroys the relative relationship between model parameters and rays and affects the inversion stability.By testing the performance of first-arrival wave travel time-based tomography inversion under different initial models,this study proposed a first-arrival wave travel time-based tomography inversion method with surface wave information as constraints.The process of this method is as follows:(1)Given that surface waves feature high energy and frequency dispersion in seismic data,the surface-wave frequency dispersion curves are obtained through the multi-channel analysis of surface waves;(2)Using the damped least squares method,the shallow-surface shear wave (S-wave) velocities are determined through inversion;(3)With the S-wave velocity structure as the constraint,the initial compressional wave (P-wave) model is established,and accordingly,the first-arrival wave travel time-based tomography inversion that considers regularization is achieved.This method improves the accuracy and stability of shallow structure inversion by fully utilizing the surface wave information in seismic data to counteract the inherent defects of tomography inversion.The effectiveness of this method has been verified using actual data.

Table and Figures | Reference | Related Articles | Metrics
Artificial neural network-based transient electromagnetic imaging
YOU Xi-Ran, ZHANG Ji-Feng, SHI Yu
Geophysical and Geochemical Exploration    2023, 47 (5): 1206-1214.   DOI: 10.11720/wtyht.2023.1547
Abstract161)   HTML3)    PDF (4517KB)(222)      

The transient electromagnetic method (TEM) commonly uses the all-time apparent resistivity parameter for interpretation, which involves complex formulas and time-consuming iterative processes. Based on the characteristics of TEM data, this study employed the artificial neural network (ANN) for TEM pseudo-resistivity imaging. First, this study designed a multi-hidden-layer BP neural network and calculated a response amplitude through TEM analysis. The response amplitude, as the mapping parameter of pseudo resistivity, was used for network training. Then new data outside the training set were used to test the trained network. A homogeneous half-space and one-dimensional layered model was built to verify the correctness and adaptability of the neural network. The imaging of the three-dimensional geoelectric model was performed. As revealed by the results, the pseudo resistivity calculated based on the neural network can reflect the target anomalies of the geoelectric model, with highly accurate network imaging results. Finally, the measured data were processed using the neural network algorithm, further indicating that the neural network-based imaging can serve as a basis for data interpretation. This study verified the feasibility of the ANN in TEM imaging, thus providing a new approach for TEM imaging.

Table and Figures | Reference | Related Articles | Metrics
Advances in research on the distributed optical fiber acoustic sensing system in the field of geophysical exploration
ZHOU Shao-Yu, BAO Qian-Zong, SHI Wei
Geophysical and Geochemical Exploration    2024, 48 (2): 411-427.   DOI: 10.11720/wtyht.2024.1304
Abstract152)   HTML5)    PDF (7793KB)(158)      

Distributed acoustic sensing (DAS) technology, one of the most advanced sound field detection technologies, can achieve distributed, long-distance, and high-precision real-time detection of the ambient vibration and sound field information interacting with optical fiber. The optical fiber exploration system of the DAS technology solves the problems of high cost and deployment difficulty of conventional geophones in complex geological environments. In recent years, the DAS technology has experienced rapid development, especially in monitoring application scenarios that require long-term and large-scale deployment. However, its systematic understanding is insufficient due to divergent research results. To further understand the research advances of the DAS technology in geophysical exploration for more effective subsequent research, this study systematically classified and summarized the development history of the DAS technology and its recent research results in geophysical exploration based on the oil and gas, marine, and environmental engineering application scenarios through literature research. This study focused on the development process of the DAS technology in different directions, the research advances in data processing, and relevant literature with specific results. Finally, this study generalized the development trend and urgent problems of the DAS acquisition system, analyzing the DAS development prospect.

Table and Figures | Reference | Related Articles | Metrics
Application of comprehensive geophysical prospecting in exploration of the Duhu copper deposit in Xinxing County
HE Jun-Fei
Geophysical and Geochemical Exploration    2024, 48 (2): 375-381.   DOI: 10.11720/wtyht.2024.1101
Abstract152)   HTML11)    PDF (5778KB)(159)      

Since individual geophysical exploration methods suffer the multiplicity of solutions, comprehensive geophysical prospecting has been extensively applied in deep ore prospecting presently. This study conducted the geological exploration of the Duhu porphyry copper deposit in Xinxing County using multiple geophysical methods such as high-precision magnetic survey and controlled source audio-frequency magnetotellurics (CSAMT). It was inferred that the CSAMT-derived medium-low resistivity anomalies and the low-gentle anomalies derived from the high-precision magnetic survey serve as significant prospecting indicators. Satisfactory results were achieved in follow-up verification of the anomalies. Specifically, copper, molybdenum, silver, and gold mineralized bodies with a cumulative thickness of 178.2 m were identified in a 1 000 m deep borehole, with the highest copper grade of 1.45%. The application of comprehensive geophysical prospecting holds great significance in guiding the exploration of porphyry copper deposits in western Guangdong.

Table and Figures | Reference | Related Articles | Metrics
Calculation and analysis of zero drift rates of gravimeters in two-way reciprocal observations based on different specifications
CHANG Xiao-Peng, CHEN Liang, ZHANG Xiang, ZHANG Ling-Xiao, ZHU Zhang-Liu, QIAO Yan-Yi
Geophysical and Geochemical Exploration    2023, 47 (5): 1307-1315.   DOI: 10.11720/wtyht.2023.1526
Abstract149)   HTML0)    PDF (928KB)(152)      

Gravity survey is an important part of geodetic mapping and geophysical exploration. Different gravity specifications adopt different methods to calculate the zero drift rates in two-way reciprocal observations (i,j,j',i'). The repeated measurements of point j are subjected to static drift in the geological survey specification. By contrast, the zero drift rate is calculated through regression analysis in the petroleum specification. Different processing methods for the repeated measurement interval of point j yield significantly different zero drift rates based on the two specifications. Through theoretical formula analysis and comparison of measured data, this study analyzed the influence of g'j- g j and t'j-tj in the repeated measurements of point j on the calculation of the zero drift rate. By comparing with the regression analysis, this study illustrated the importance of static drift in reducing the uncertainties caused by instrument performance and measurement environment. Moreover, this study proposed the applicable conditions of the two specifications.

Table and Figures | Reference | Related Articles | Metrics
Feasibility of the transient electromagnetic method in the exploration of double-layer waterlogged goafs with different layer spacings in coal mines
ZHANG Fan, FENG Guo-Rui, QI Ting-Ye, YU Chuan-Tao, ZHANG Xin-Jun, WANG Chao-Yu, DU Sun-Wen, ZHAO De-Kang
Geophysical and Geochemical Exploration    2023, 47 (5): 1215-1225.   DOI: 10.11720/wtyht.2023.1525
Abstract148)   HTML6)    PDF (5416KB)(260)      

It is difficult to explore the overlapping double-layer waterlogged goafs using the transient electromagnetic method. The reason is that upper waterlogged goafs will hinder the propagation of the electromagnetic field, thus prolonging the observation of the lower waterlogged goafs and reducing the signal-to-noise ratio. Besides, the burial depths and layer spacings of double-layer waterlogged goafs affect the signal-to-noise ratio and the observation time of transient electromagnetic signals. By building a double-layer waterlogged goaf model based on the Majiayan coal mine in Shanxi, this study analyzed the electromagnetic field propagation under layer spacings of 25 m, 50 m, 75 m, and 100 m,and calculated the observation time of waterlogged goafs with different layer spacings. Furthermore, it quantitatively characterized the differences between induced voltages in the double-layer waterlogged goafs with different layer spacings using root mean square errors. Additionally, this study proposed the identification criteria for explorable lower waterlogged goafs based on the record errors and noise levels during the observation. The results of physical simulation experiments are as follows: The differences between the induced voltages of double-layered waterlogged goafs with different layer spacings occur mainly in the late stage; the differences between induced voltages gradually decrease as the layer spacing and the burial depth of upper waterlogged goafs increases; the difference between induced voltages is close to the noise level when the layer spacing is greater than 75 m. The actual detection of the double layer waterlogged goaf with a spacing of 75 meters was conducted in Majiayan Coal Mine, and the results showed that the lower waterlogged goaf was not effectively identified.Therefore, It is difficult to effectively explore the lower waterlogged goafs when the layer spacing is greater than 75 m.

Table and Figures | Reference | Related Articles | Metrics
A method for strong noise suppression based on DC-UNet
ZHOU Hui, SUN Cheng-Yu, LIU Ying-Chang, CAI Rui-Qian
Geophysical and Geochemical Exploration    2023, 47 (5): 1288-1297.   DOI: 10.11720/wtyht.2023.1386
Abstract138)   HTML0)    PDF (6456KB)(147)      

Seismic data acquired from mature industrial areas frequently contain a large amount of local strong noise with high amplitude due to the continuous operation of production equipment.However,such local strong noise can be hardly suppressed using conventional denoising methods.This study integrated dilated convolution(DC) and U-Net into a DC-UNet network for suppressing local strong noise.For the circular DC blocks at the front end of the DC-Unet network,a circularly expanded DC kernel was used to extract the features of strong noise at different scales,with the receptive field being expanded.Meanwhile,an encoder was used at the back end of the network to extract the features of strong noise and restore the details of strong noise.Subsequently,the DC-UNet network was employed to perform a nonlinear mapping from noisy data to noise.On this basis,strong noise was suppressed by subtracting the learned strong noise from the noisy data.As indicated by the experimental results of synthetic and real data obtained from the training using the PyTorch framework in the GPU environment,the DC-UNet network can effectively suppress the local strong noise and improve the signal-to-noise ratio compared with DnCNN,U-Net,and PCA-UNet networks.

Table and Figures | Reference | Related Articles | Metrics
Application of the integrated geophysical exploration technology in the exploration of deep carbonate geothermal reservoirs: A case study of the Xiong'an New Area
ZHANG Zhao, YIN Quan-Zeng, ZHANG Long-Fei, ZHANG Da-Ming, ZHANG Shi-Hui, HUANG Guo-Shu, ZHAO Shi-Feng, YANG Biao, TAI Li-Xun, ZHANG Deng-Liang, WANG Jin-Chao, DUAN Gang
Geophysical and Geochemical Exploration    2023, 47 (4): 926-935.   DOI: 10.11720/wtyht.2023.1354
Abstract134)   HTML3)    PDF (7787KB)(220)      

Xiong'an New Area has great potential for geothermal resources. Carbonate rocks are favorable reservoirs for deep geothermal resources in this area. The integrated geophysical exploration technology is an effective way to ascertain the deep structures and the characteristic stratigraphic structure of carbonate geothermal reservoirs. Aiming at the exploration target of deep carbonate geothermal reservoirs, this study put forward a surface-line-point hierarchical and progressive geophysical exploration model. Using the high-precision gravity and aeromagnetic data, this model first investigated the distribution range of carbonate rocks, the thickness of carbonate strata, the distribution of deep-seated faults, and the fluctuation of bedrocks. Then, it analyzed the low-resistivity anomalies of geothermal reservoir strata using the magnetotelluric method. Finally, this model finely characterized the geothermal reservoir strata using two-dimensional seismic profiles and analyzed the velocity structure and regional structural characteristics of anomaly zones in the geothermal field. Based on the exploration precision and reliability of gravity, aeromagnetic, magnetotelluric, and seismic geophysical methods in the geothermal resource exploration of different stages, as well as other factors such as construction cost and efficiency, this study analyzed the economic applicability of geophysical methods in the exploration of deep karst geothermal reservoirs and suggested that the carbonate geothermal resources should be explored using the geophysical exploration technology combination of gravity, magnetic, and magnetotelluric methods.

Table and Figures | Reference | Related Articles | Metrics
Research on time-frequency electromagnetic method detection of Wumishan Formation thermal reservoir in deep Xiong’an New Area
Cheng Zheng-Pu, Lian Sheng, Wei Qiang, Hu Wen-Guang, Lei Ming, Li Shu
Geophysical and Geochemical Exploration    2023, 47 (6): 1400-1409.   DOI: 10.11720/wtyht.2023.1611
Abstract127)   HTML6)    PDF (2331KB)(227)      

Xiong’an New Area is one of the areas with the best conditions for the development and utilization of geothermal resources in sedimentary basins of eastern China. Wumishan Formation of Jixian System is the main thermal reservoir, with buried depth of the top boundary varies greatly, which istypical carbonate type thermal reservoir. In order to find out the stratigraphic structure and concealed faults within 6 km of the starting area of Xiong’an New Area, focus on finding out the spatial distribution and structural characteristics of the main deep thermal reservoirs, and predict the favorable geothermal areas, the time-frequency electromagnetic method is applied to the geothermal resources exploration of Xiong’an New Area. Through high-standard data acquisition, refined data processing and resistivity-constrained inversion, the pseudo-seismic imaging technology and borehole data are used to calibrate the resistivity horizon, which effectively improves the reliability of interpretation results. In this work, 8concealed faults were identified, mainly NNE strike normal faults, which controlled the salient-depression pattern and stratigraphic distribution of the study area. The study area is divided into Rongcheng salient, middle sub-depression, Niutuozhen salient and Baxian depression from west to east. The thermal reservoirs of Wumishan Formation is mainly distributed in Niutuozhen salient, Rongcheng salient and middle sub-depression, with buried depth of top interface is about 600~2600m. Vsing the inversion results of the time-frequency electromagnetic method, the three-dimensional geological model of the study area is constructed, and the Niutuozhen salient area is considered to be the optimal geothermal favorable area from the aspects of heat source, channel, reservoir, caprock and fluid, especially near the footwall of F4.

Table and Figures | Reference | Related Articles | Metrics
Correction of the influence of mountains on grounded-source transient electromagnetic responses
ZHOU Zhong-Hang, ZHANG Ying-Ying
Geophysical and Geochemical Exploration    2023, 47 (5): 1236-1249.   DOI: 10.11720/wtyht.2023.1489
Abstract124)   HTML1)    PDF (5591KB)(213)      

The grounded-source transient electromagnetic (TEM) method, which enjoys the advantages of high topographic adaptability and large exploration depths, is suitable for deep resource exploration in mountainous areas. However, the TEM responses can be distorted due to topographic effects, causing great difficulties in data interpretation. This study investigated the influence patterns and correction method of topographic effects based on the three-dimensional unstructured time-domain finite element method. First, this study conducted the fine-scale description of mountains using unstructured tetrahedral grids, calculated the response of various topographic models, and analyzed the influence patterns of topographic effects. Then, it proposed a correction method for topographic effects based on the principle of the linear superposition principle of electromagnetic fields, established a geoelectric model of mountains according to the actual elevation data, and calculated the model responses through three-dimensional forward modeling. Subsequently, this study determined the topographic responses by subtracting the flat Earth model responses from the mountain model responses and then obtained the corrected TEM responses by removing the topographic responses from the total responses. The results are as follows: (1) The influence of mountains on the TEM responses is concentrated in the early stage and weakens gradually with time; (2) The topographic effects are concentrated near mountains, and their intensity depends on the distance of survey points from mountain peaks; (3) The influencing range and response amplitude of mountains are proportional to the mountain scale. In other words, a larger mountain scale corresponds to a larger influencing range and higher response amplitude; (4) Mountains with relatively high resistivity show more intense topographic influence. As shown by multiple models with simple and regular topographic anomalies, the corrected TEM responses, which match well with the responses from direct forward modeling, can effectively eliminate topographic effects to a certain extent. The research on the influence and correction method of topographic effects can be used as a reference for the processing and interpretation of TEM data of areas with complex terrain.

Table and Figures | Reference | Related Articles | Metrics
Common problems and solutions in the use of instrument calibration points in high-precision ground magnetic surveys in the field
GENG Tao
Geophysical and Geochemical Exploration    2023, 47 (4): 1078-1082.   DOI: 10.11720/wtyht.2023.1358
Abstract124)   HTML0)    PDF (1837KB)(195)      

To ensure the high quality of data acquisition in high-precision ground magnetic surveys in the field, it is an important link to ascertain the instrument performance in a period using instrument calibration points. However, some workers fail to properly use instrument calibration points and thus fail to monitor the operation state of instruments on a day through the early and late calibration measurement of the instruments, affecting the acquisition of high-precision magnetic survey data. Based on the analysis of specific examples, this study proposed that the checking of early and late calibration measurement results of instruments should consider both the differences between these results, as well as the differences between these results and the actual magnetic field values of instrument correction points. The purpose is to ensure the high-quality field acquisition of high-precision magnetic survey data.

Table and Figures | Reference | Related Articles | Metrics
Characterization of multi-attitude fractures in tight sandstones in the Yuanba area, northeastern Sichuan Basin
HUANG Yan-Qing
Geophysical and Geochemical Exploration    2023, 47 (5): 1189-1197.   DOI: 10.11720/wtyht.2023.1352
Abstract123)   HTML3)    PDF (9055KB)(137)      

This study proposed a fracture prediction method based on unsupervised clustering of fracture sensitivity attributes to accurately characterize the distribution of fractures with different attitudes in tight sandstones of the Upper Triassic Xujiahe formation in the Yuanba area, northeastern Sichuan. First, the sensitivity of fractures was extracted and selected based on the optimized post-stack seismic data. Then, the convolutional neural network, a deep learning algorithm, was used to learn global massive fault and fracture databases of various types, obtaining the intensities, dip angles, and azimuths of fractures. In combination with high-precision-guided curvature attributes, an unsupervised clustering algorithm based on the Bayesian probability model was used to predict the intensities of fractures with different dip angles through dimensionality reduction using principal component analysis (PCA). The prediction results are highly consistent with both the fracture interpretation results from imaging logs and the geological results. The results of this study show that the third member of the Xujiahe Formation has more developed fractures than the second member. Fractures in the third member include both the fault-induced fractures distributed near the faults in the southeast flank of the Jiulongshan anticline and the fold-induced fractures in the areas with large formation flexures. By contrast, only fault-induced fractures near the faults occur in the second member.

Table and Figures | Reference | Related Articles | Metrics
Geophysical characteristics and deep prospecting prediction of the Dachaigou gold deposit in the eastern Kunlun area
YU Zhong-Hong, YAN Ling-Qin, ZHANG Zhan-Xiong, LI Peng, LI Feng-Ting, FU Jia
Geophysical and Geochemical Exploration    2024, 48 (1): 40-47.   DOI: 10.11720/wtyht.2024.1126
Abstract118)   HTML5)    PDF (7232KB)(236)      

The eastern Kunlun metallogenic belt, as a significant metal metallogenic belt in China, hosts extensive orogenic gold deposits and large-scale Kunlunhe, Gouli, and Wulonggou gold concentration areas. The Dachaigou gold deposit is a large-scale gold deposit newly discovered in the Wulonggou gold field in recent years. Despite its high metallogenic potential, the western extension of its ore belt has not been defined. Hence, this study conducted induced polarization (IP) sounding and wide-field electromagnetic sounding in the deposit. The results show that the known ore belt is situated in the regional gravity anomaly gradient zone, the transition zone of positive and negative weak magnetic anomalies, the edge of IP anomalies, or the electrical gradient zone. The development zone of the regional tectonic belt resides in the large-scale IP anomaly section. The regional tectonic belt is characterized by a wide range of low-resistivity anomaly zones. The IV and III alteration zones of the known ore belt are located in the opening position of the low-resistivity anomaly zone and the shallow electrical anomaly gradient zone, respectively. Based on the above understanding and the electromagnetic anomaly change patterns of several parallel profiles in the western extension segment, it was inferred that the regional ore-controlling structure extends steadily in the W-NWW direction, forming a favorable prospecting space in the western extension segment of the deposit. The results of deep geophysical exploration in the Dachaigou deposit indicate that geophysical methods manifest significant advantages in deep geological prospecting research, providing successful experience for deep prospecting in the eastern Kunlun gold deposit area.

Table and Figures | Reference | Related Articles | Metrics
Critical factors in microtremor-based exploration at a depth of thousands of meters
QI Juan-Juan
Geophysical and Geochemical Exploration    2024, 48 (3): 777-785.   DOI: 10.11720/wtyht.2024.1358
Abstract118)   HTML2)    PDF (6323KB)(83)      

To explore the critical factors influencing the results of microtremor-based exploration at a depth of thousands of meters,this study conducted experiments using triangular arrays based on spatial autocorrelation(SPAC) and extended SPAC(ESPAC).Focusing on factors such as array size,acquisition unit frequency,and acquisition duration,this study explored the frequency band ranges corresponding to different array sizes,the arrangement of arrays in kilometer-depth exploration for obtaining both deep and shallow data,and the improvement in deep resolution.Based on the analysis and discussion results,this study established a parameter-setting system to improve the accuracy of exploration at a depth of thousands of meters.

Table and Figures | Reference | Related Articles | Metrics
Geological characteristics and origin of the Mogou fluorite deposit in Fangcheng County, Henan Province
ZHANG Qing-Song, XIA Ming-Zhe, WANG Chun-Lian, LI Ke-Kun, LIU Zeng-Zheng, JIANG Ji-Yong, JIANG Jian-Lang
Geophysical and Geochemical Exploration    2024, 48 (1): 15-23.   DOI: 10.11720/wtyht.2024.2588
Abstract116)   HTML6)    PDF (6964KB)(130)      

The Mogou fluorite deposit of Fangcheng County, residing in the Neoproterozoic Meiyaogou Formation, is a crucial part of the fluorite metallogenic belt in southern Henan Province. Based on the analysis of the geological characteristics of the Mogou fluorite deposit, this study conducted petrographic and petrogeochemical studies to define the source of ore-forming materials and probe into the genetic mechanism of the fluorite deposit. The results show that the fluorite ore body is veined or lenticular, with mineralization-related alterations composed of silicification, fluorite and sericite alterations. Its ore structures are primarily massive, followed by banded, striped, and brecciated types. The chondrite-normalized rare earth element distribution pattern of the fluorite ore body is similar to that of the Meiyaogou Formation marbles and the Yanshanian porphyritic plagiogranites, suggesting a genetic relationship. The possible genetic mechanism is that the F-enriched ore-bearing hydrothermal liquids intruded along the interbedded fault and reacted with the surrounding rocks to form the fluorite ore /mineralized body. The deposit belongs to the epithermal filling type along the interbedded structure.

Table and Figures | Reference | Related Articles | Metrics
Application of the multi-dimensional study of geochemical anomalies in deep metallogenic prediction of the Zhexiang gold deposit in southwestern Guizhou, China
TAI Wen-Xing, YANG Cheng-Fu, JIN Xiao-Ye, SHAO Yun-Bin, LIU Guang-Fu, ZHAO Ping, WANG Ze-Peng, TAN Li-Jin
Geophysical and Geochemical Exploration    2023, 47 (4): 856-867.   DOI: 10.11720/wtyht.2023.1338
Abstract116)   HTML3)    PDF (8849KB)(196)      

Due to the lack of effective deep exploration techniques, it has become a key and difficult task to expand the scale of prospecting by obtaining the mineralization information in the deep and peripheral areas of the proven typical deposits of the Huijiabao anticline in southwestern Guizhou. To truly reflect the characteristics of deep geological anomalies, this study investigated the deep ore-bearing Longtan Formation of the Zhexiang gold deposit in the eastern Huijiabao anticline. The information on deep Au anomalies was extracted through geochemical exploration in boreholes of any azimuth according to the profiles, longitudinal profiles, and deep 3D planes of survey lines. Then this study summarized the distribution patterns of geochemical anomalies and evaluated the deep metallogenic potential of the Zhexiang gold deposit. The geochemical data obtained from deep boreholes were processed using the iterative histogram method and the sample length weighted average grade method, respectively. The results show that the Longtan Formation in the mining area had Au anomaly background values of (0.04~0.12)×10-6 and an anomaly threshold of about 0.24×10-6. As revealed by the anomaly contour maps generated from the processed data using the above two methods, the distribution characteristics of Au anomalies are in high agreement with those of deep ore bodies, and the distribution ranges of high Au anomalies in all profiles are highly consistent with the morphologies of the proved ore-bearing zones (bodies). Moreover, the large-scale and unclosed high Au anomalies follow the dip direction of fault F20 in the first member of the Longtan Formation. The 3D distribution of Au anomalies shows that the nearly EW-directed high anomaly zone in the central mining area is consistent with the axial region of the Huijiapu anticline. As indicated by the analysis of the multi-dimensional geochemical anomalies and the geological characteristics of the study area, fault F20 is the main ore transmitting and controlling fault in the mining area, and the northern and eastern deep parts around the mining area have great metallogenic and prospecting potential. In addition, two prospecting targets were delineated, needing further engineering verification. This study plays an important demonstration role in guiding the exploration of other mining areas in the Huijiabao anticline. The feasible study methods can be referenced for the study of geochemical anomalies in other mining areas.

Table and Figures | Reference | Related Articles | Metrics
Design and implementation of key technologies for real-time three-dimensional ground-penetrating radar
YIN Da, XIN Guo-Liang, SUN Xue-Chao, ZHANG You-Yuan, ZHANG Qi-Dao
Geophysical and Geochemical Exploration    2024, 48 (1): 194-200.   DOI: 10.11720/wtyht.2024.1030
Abstract115)   HTML0)    PDF (3013KB)(173)      

To improve the detection level of municipal roads for rapid and effective municipal road collapse warning and rapid search for municipal pipe network distribution, the 22nd Research Institute of China Electronics Technology Group Corporation designed and developed real-time three-dimensional ground-penetrating radar (3D GPR). With the real-time 3D GPR, which is based on the architecture of field programmable gate array and digital signal processor (FPGA&DSP), the institute achieved the design and implementation of several key technologies for the multi-channel high-speed acquisition system, enriching the road detection techniques and methods. The real-time 3D GPR enables high-speed acquisition of ten-channel radar data using the horizontally polarized antennae equipped with five transmitters and six receivers. The channels can be switched using high-speed switches, which operate in an interactive interpolation manner. The 3D GPR allows for up to 32 channels and detection speeds of above 60 km/h (channel interval: 2 cm). This is attributed to the switching of the antenna array using switches. The optimum antenna polarization design was verified by the comparison of experimental data from cavity- and metal-plate-based experimental sites. As a result, the optimal antenna scheme was determined. The measured results show that, compared to general LTD-2600 radar, the real-time 3D GPR boasts a higher acquisition speed and higher performance in terms of amplitude and phase, conducive to the improvement of road disaster detection technologies. Therefore, there is high market demand for the real-time 3D GPR.

Table and Figures | Reference | Related Articles | Metrics
A processing method for seismic data consistency under complex surface conditions and its applications
CHEN Chao-Qun, DAI Hai-Tao, GAO Qin, CHEN Jun-Jie, LUO Wen-Li, WANG Zhi-Ru
Geophysical and Geochemical Exploration    2023, 47 (4): 954-964.   DOI: 10.11720/wtyht.2023.1162
Abstract113)   HTML2)    PDF (14044KB)(175)      

Located in the loess tableland area,the eastern Ordos Basin features criss-cross ravines and gullies and great topographic fluctuations.Its complex surface conditions and near-surface structures caused significantly different amplitudes,frequencies,and phases in the original seismic data of different regions.These differences are unrelated to the subsurface geological information and can easily lead to misinterpretation.Therefore,there is an urgent need to develop a processing method for seismic data consistency according to the characteristics of seismic data in the study area,aiming to improve the fidelity of seismic data.Based on the summary of the current consistency processing methods,this study built a new consistency processing flow for seismic data under complex surface conditions.By innovating surface consistent amplitude compensation,this study employed the dual-domain near-surface Q-absorption compensation for the first time to broaden the frequency band and improve the amplitude and frequency consistency of seismic data collected across gullies and tablelands.In addition,this study applied the surface consistent deconvolution of Yu's wavelet to attenuate the low-frequency noise and broaden the effective signal frequency band,improving the signal-to-noise ratio,resolution,and wavelet consistency of seismic data.The actual application verifies that the method used in this study is feasible and effective and has a high popularization value.

Table and Figures | Reference | Related Articles | Metrics
Exploring the Rayleigh wave propagation characteristics in different aggregate concrete models
XIANG Zhu-Bao, ZHANG Da-Zhou, ZHU De-Bing, LI Ming-Zhi, XIONG Zhang-Qiang
Geophysical and Geochemical Exploration    2023, 47 (5): 1226-1235.   DOI: 10.11720/wtyht.2023.0086
Abstract112)   HTML0)    PDF (1444KB)(142)      

To avoid aggregate interference on the detection target in concrete quality detection by Rayleigh waves, the abnormal signals from the aggregate and the target should be distinguished for high detection reliability. Hence, this study explored the propagation characteristics of Rayleigh waves in aggregate concrete. By building the mesostructural random aggregate models and employing the high-order staggered-grid finite difference scheme, this study examined the effects of the randomness, shape, size, and content of aggregate on the Rayleigh wave field and dispersion curves, thus obtaining the Rayleigh wave scattering, energy attenuation, distortion, and dispersion curve characteristics under different aggregate parameters. Based on the forward modeling data of different aggregate concrete models, this study quantitatively analyzed the sizes and influence ranges of aggregate-induced anomalies of the Rayleigh wave field and dispersion curves. The results are as follows. The randomness and content of aggregate could affect the energy attenuation of direct Rayleigh waves. The Rayleigh wave field was slightly influenced by the aggregate shape but significantly impacted by the aggregate size. When the aggregate size exceeded half of the dominant wavelength, Rayleigh waves would produce strong scattering, distorting its waveforms. In contrast, these aggregate parameters caused no anomalies in the dispersion curves. Therefore, data analysis using dispersion curves can avoid aggregate interference on the target in concrete quality detection by Rayleigh waves.

Table and Figures | Reference | Related Articles | Metrics
Heavy metal pollution and health risk assessment of groundwater in a typical chemical industry park in northwestern Shandong, China
FAN Hai-Yin, SONG Rui-Rui, YU Lin-Song, TENG Yong-Bo, WAN Fang, ZHANG Xiu-Wen, LI Sheng-Yu, ZHAO Chuang
Geophysical and Geochemical Exploration    2023, 47 (5): 1326-1335.   DOI: 10.11720/wtyht.2023.1367
Abstract112)   HTML2)    PDF (4861KB)(177)      

This study aims to ascertain the heavy metal pollution of groundwater in a typical chemical industry park in northwestern Shandong. According to the investigation and evaluation requirements for groundwater environments in chemical industry parks, this study collected 10 groundwater samples to analyze the concentrations and spatial distributions of eight heavy metals, namely Fe, Cu, Zn, Al, Cd and Pb. Furthermore, it conducted the health risk assessment of groundwater for different populations. The results indicate that: (1) except Mn and Al, all heavy metals in the groundwater of the chemical industry park showed concentrations lower than the class III water quality standard stated in the Standard for Groundwater Quality (GB/T 14848—2017), with a comprehensive pollution index ranging from 0.37 to 0.78. The monitoring points for heavy metal elements are all pollution-free; (2) the overall spatial distributions of heavy metals are roughly consistent with the distribution areas of key enterprises in the chemical industry park. This consistency indicates that external factors such as the production activities of enterprises affect the spatial distributions of heavy metals in groundwater; (3) the health risks are lower for children than for adults and lower via skin contact than via drinking. The non-carcinogenic risks under different exposure routes are acceptable for different populations. Carcinogens As and Cd have slight carcinogenic risks for adults. Local authorities should strengthen the supervision of the production activities of enterprises and thoroughly inspect enterprises with suspected pollution. Only in this way can we effectively control and then gradually reduce the risks to human health caused by groundwater pollution.

Table and Figures | Reference | Related Articles | Metrics
Application of the minimum entropy method based on a velocity-controlled moving window to the reverse time migration of ground-penetrating radars
XI Yu-He, WANG Hong-Hua, WANG Yu-Cheng, WU Qi-Ming
Geophysical and Geochemical Exploration    2023, 47 (5): 1250-1260.   DOI: 10.11720/wtyht.2023.1556
Abstract111)   HTML1)    PDF (6342KB)(166)      

Velocity is a key parameter determining the migration imaging resolution of ground penetrating radars (GPR).The method combining minimum image entropy and migration usually estimates the medium velocity by calculating the entropy curves using the overall migration profile as a fixed window.Therefore,such a method is not applicable to non-uniformly distributed media.Moreover,for this method,a too-high or too-low test velocity will make the convergence position of hyperbolic diffracted waves go beyond the fixed window,thus reducing the estimation accuracy.This study proposed a minimum entropy method based on a velocity-controlled moving window,in which the calculation window in the migration profile is accurately controlled by the test velocity.Then,this method was combined with inverse time migration to estimate the optimal migration velocity.By automatically adjusting the position of the calculation window using the trial velocity,this method keeps the convergence position of hyperbolic diffracted waves at the center of the calculation window.In this manner,stable and accurate entropy curves can be obtained.By comparing the calculation results with those of the minimum entropy method based on a fixed window,this study verified the correctness and effectiveness of the minimum entropy method based on a velocity-controlled moving window for a typical hyperbolic diffracted wave.As revealed by numerical experiments and the tests of measured data,compared with the minimum entropy method based on a fixed window,the minimum entropy method based on a velocity-controlled moving window can keep the convergence position of hyperbolic diffracted waves accurately at the center of the calculation window,yielding more stable entropy curves,lower computational complexity,higher estimation accuracy of the migration velocity,and better imaging performance of reverse time migration.

Table and Figures | Reference | Related Articles | Metrics
Delineation of areas with high geological background values of heavy metals in soils in Yunnan Province, China based on geological big data technology
XIAO Gao-Qiang, ZHAO Juan, CHEN Zi-Wan, SONG Xu-Feng, ZHU Neng-Gang
Geophysical and Geochemical Exploration    2024, 48 (1): 216-227.   DOI: 10.11720/wtyht.2024.1129
Abstract111)   HTML3)    PDF (4168KB)(136)      

This study aims to systematically investigate the distribution and over-limit elements of areas with high geological background values of heavy metals in soils in Yunnan Province. GIS spatial analysis was conducted based on the heavy metal content data from a province-wide 1∶200,000 stream sediment survey and the regional geological map. The analysis results were validated using the data of heavy metals in soils in Kunming, Yuxi, Zhaotong, and other regions. A total of 61 geological units were identified, with heavy metal content in soils exceeding the screening values of agricultural land, accounting for 21.09% of the total land area of Yunnan. The cultivated land in high geological background areas covers an area of approximately 2.844 1 million hectares, accounting for 7.22% of the total land area of Yunnan. The lithologies that cause over-limit heavy metals in soils primarily comprise carbonate rocks, mafic-ultramafic volcanic rocks, intermediate mafic intrusive rocks, coal-bearing clastic rocks, and clastic rocks with mafic components. The over-limit heavy metal elements in high geological background areas are dominated by Cu, Cr, Ni, and Cd. In contrast, As manifests an over-limit risk mainly in carbonate rock formations, Pb and Zn only exhibit an over-limit risk in individual strata, and Hg almost shows no over-limit risk.

Table and Figures | Reference | Related Articles | Metrics
Fine-scale prospecting targets of skarn iron deposits in the Pandian gravity-magnetic anomaly zone of northwestern Shandong Province: Insights from deep prospecting using the wide-field electromagnetic method
GUO Guo-Qiang, LI Ya-Dong, WANG Yang, YU Jia-Bin, WANG Run-Sheng, GAO Xiao-Feng, ZHANG Da-Ming, HU Dong-Ning, FANG Lei, GUO Wei-Fang
Geophysical and Geochemical Exploration    2024, 48 (2): 327-333.   DOI: 10.11720/wtyht.2024.1157
Abstract111)   HTML3)    PDF (4258KB)(168)      

Significant aeromagnetic and gravity anomalies were found in the ultra-deep coverage zone of the Pandian area in the northwestern Shandong Province. Through systematic verification of gravity and magnetic anomalies, a breakthrough in prospecting for deep skarn iron deposits has been achieved through several boreholes around the Pandian gravity-magnetic anomaly zone. However, the gravity-magnetic anomaly zone spreads extensively and its characteristics cannot directly indicate the prospecting target, thus some boreholes failed to find ores or revealed poor ore-finding conditions. Hence, to accurately delineate the ore-forming location in the gravity-magnetic anomaly zone and achieve a further breakthrough in ore prospecting, this study conducted the wide-field electromagnetic (WFEM) sounding in the verified Pandian gravity-magnetic anomaly zone. Combining the drilling verification, this study delineated the deep ore-forming interval of skarn iron deposits in the deep coverage zone and the favorable structural plane for ore-forming, suggesting the deep fine-scale prospecting targets.

Table and Figures | Reference | Related Articles | Metrics
Application of tectonic primary halos in the exploration of deep concealed ore bodies: A case study of the Niuxingba plumbum-zinc-gold-silver deposit in Yinkeng, southern Jiangxi
CHEN Wei, TAN You, CAO Zheng-Duan, LIAO Zhi-Quan, ZHANG Ning-Fa, FU Hai-Hui
Geophysical and Geochemical Exploration    2023, 47 (4): 892-905.   DOI: 10.11720/wtyht.2023.2625
Abstract109)   HTML1)    PDF (8961KB)(204)      

The Niuxingba plumbum-zinc-gold-silver deposit (the Niuxingba deposit) occurs in the Yinkeng ore field at the intersection of the EW-trending Nanling metallogenic belt and the NNE-striking Wuyishan metallogenic belt. It is a typical hydrothermal vein deposit under the strict control of fault structures, with ore bodies occurring as vein groups. To predict the deep prospecting potential of the No. V31 major ore belt (body) of the Niuxingba deposit, this study systematically investigated the axial (vertical), transverse, and longitudinal geochemical characteristics and zoning of tectonic primary halos of the ore belt (body) based on the geological characteristics of the deposit. Then, this study determined the axial zoning sequence and the geological-geochemical model of tectonic primary halos. It was confirmed that this model was correct, reasonable, and reliable using the multivariate statistical method. The results of the geological-geochemical model show that: ① the front halo of the Niuxingba deposit has F as the indicator element; ② the near-ore halo has two types of indicator elements: the gold mineralization-related As-Au element association in the middle and upper parts of the ore body and the Pb-Zn-Ag mineralization-related Hg-Zn-Pb-Ag-Cu-Bi-Sb element association in the middle part of the ore body; ③ the rear halo has the Mo-Cr-Co-Ni element association as indicator elements; ④ the anomaly centers of the front, near-ore, and rear halos are about 200~300 m apart axially, suggesting significant coexistence of front and rear halos and the presence of inflection points of the near-ore halo broken line. Furthermore, the transformation of low-moderate-temperature Pb-Zn-Ag-Au mineralization into moderate-high-temperature Cu-Zn mineralization occurs eastward. These characteristics indicate that the No. V31 main ore belt (body) has a pitch direction of east and a large extension toward the deep part (to an elevation of -200 m at least), implying that blind ore bodies may occur. As verified by deep drilling in the eastern concealed area (the lowest ore-controlled elevation of the No. 367 survey line: -165 m), the eastern deep part of the No. V31 ore belt (body) has a high potential for increasing reserves.

Table and Figures | Reference | Related Articles | Metrics
Three-dimensional imaging based on the ultrasonic planar array-total focusing method
ZHANG Bang
Geophysical and Geochemical Exploration    2023, 47 (5): 1273-1280.   DOI: 10.11720/wtyht.2023.1414
Abstract108)   HTML0)    PDF (3504KB)(180)      

Given large data volumes and low post-processing efficiency of full matrix capture-total focusing imaging,this study proposed a planar array-total focusing method(PATFM) for the imaging of planar array data.First,the wave front time of the downgoing planar array was calculated using the eikonal equation based on the characteristics of both the total focusing imaging algorithm and the planar array wave field.Then,the total focusing imaging formula was improved using the upgoing and downgoing ultrasonic propagation time based on the delay superposition principle.Finally,focusing imaging was performed on a wide range of imaging points below the planar array aiming at the derived directivity and diffusion correction coefficient of the planar array.Through Field II simulation,the PATFM was compared with three imaging methods,including phase-controlled scanning imaging,full matrix capture-based total focusing imaging,and plane wave capture-based total focusing imaging.The results show that the PATFM can be used for large-range focusing imaging of single planar array data,greatly improving the computational efficiency while obtaining corresponding accuracy.Therefore,this study provides a feasible technical means for 3D imaging of array acoustic waves.

Table and Figures | Reference | Related Articles | Metrics
GIS-based assessment of the radioactivity levels and risks of soil environment
QUE Ze-Sheng, LI Guan-Chao, HU Ying, JIAN Rui-Min, LIU Bing
Geophysical and Geochemical Exploration    2023, 47 (5): 1336-1347.   DOI: 10.11720/wtyht.2023.1582
Abstract108)   HTML1)    PDF (9237KB)(133)      

Investigating the concentrations of natural radionuclides in soils is basic for soil pollution prevention and control. First, this study determined the background values and anomaly thresholds of radionuclides 238U, 226Ra, 232Th, and 40K in soils in Guangdong Province using the geographic information system (GIS) and three methods, namely conventional statistics, exploratory data analysis (EDA), and median absolute deviation (MAD). Then, this study assessed the radioactivity levels of the soil environment using four indices: the γ radiation dose rate, the equivalent radium specific activity, the external exposure index, and the annual effective dose rate. Finally, this study assessed the health risks of the soil radioactivity using the geoaccumulation index method, the single factor index method, and the Nemerow composite index method. The results indicate that: (1) Radionuclides 238U, 226Ra, 232Th, and 40K in soils of Guangdong Province have average concentrations of 79.4, 102.95, 74.59, and 541.25 (Bq·kg-1·dry), respectively; (2) The four radionuclides have background values of 34.27、46.75、32.87 and 271.79 (Bq·kg-1·dry), and the anomaly values of 111.35、141.805、105.12、946.26 (Bq·kg-1·dry); (3) The radioactivity level indices for soil environment, namely D, Raeq, Hex, and AEDR, show averages of 121.44 ± 67.08 nGy/h, 263.48 ± 147.72 Bq/kg, 0.08~2.3, and 148.93 ± 82.26 μSv/a, respectively; (4) The radionuclide geoaccumulation index suggests clean soils, the single factor index indicates slight pollution, and the Nemerow composite index of 0.22~5.52 (average: 1.74 ± 0.97) indicates mild pollution. These three indices, which suggest roughly consistent results for the health risk assessment of radionuclides in soils, can serve as a supplement to the health risk assessment method for soil radioactivity.

Table and Figures | Reference | Related Articles | Metrics
Research on the application of the integrated gravity-magnetic-radioactive geophysical exploration method in the exploration of rare earth deposit in Weishan, western Shandong
LAN Jun, LI Zhao-Ling, ZHANG Peng, LI Zhi-Min, LI De-Jian, XING Nan, SUN Li, YANG Yun-Tao, XU Hong-Yan, WANG Jian, WANG Qiao-Yun
Geophysical and Geochemical Exploration    2023, 47 (6): 1417-1424.   DOI: 10.11720/wtyht.2023.0189
Abstract107)   HTML7)    PDF (4793KB)(220)      

Since the periphery of the Xishan rare earth deposit in Weishan County, western Shandong is mostly covered by the Quaternary strata, single geophysical exploration methods are ineffective in searching for rare earth elements in this area. To establish a geological-geophysical prospecting model for deep rare earth prospecting in this area, a combination of exploration techniques and methods suitable for the deep exploration of rare earth deposits in this area were selected through multiple geophysical exploration technology experiments on the known geological profiles. The distribution range of the underground Mesozoic Xishan alkaline complex was roughly determined through gravity survey and high-precision magnetic survey. The ore body outcrop was delineated through ground-based gamma spectrometry, and the deep ore body characteristics were revealed through drilling. Finally, this study developed an integrated geophysical exploration method including gravity-magnetic joint delineation of rock masses, radioactive positioning for ore body outcrops, and deep drilling. By using this exploration model, one super-large rare earth deposit was discovered in this area, providing a reference for the exploration of rare earth deposits in the surrounding area.

Table and Figures | Reference | Related Articles | Metrics
Microtremor signal simulation and its application in microtremor exploration
LI Chuan-Jin, WANG Qiang, JIAN Xiang, ZHENG Tao, ZHAN Su-Hua, CHEN Shao-Wei
Geophysical and Geochemical Exploration    2023, 47 (4): 1040-1047.   DOI: 10.11720/wtyht.2023.1303
Abstract104)   HTML2)    PDF (3904KB)(217)      

This study synthesized microtremor signals using the normal mode superposition.The dispersion curves of the synthesized microtremor signals were calculated using the spatial autocorrelation method,and the calculated results agreed well with theoretical dispersion curves.The simulation of microtremor signals involves many parameters,which are of great significance for microtremor exploration.As shown by results from numerical experiments of these parameters,the hypocentral distance and array size had a significant influence on the results.Moreover,high-order surface waves should be considered for complex strata,while small-size arrays tended to yield high-frequency dispersion information at quiet observation sites,thus improving the resolution of shallow strata.Therefore,it is necessary to consider the influences of hypocenter distribution,array size,and high-order surface waves on exploration results in microtremor exploration.

Table and Figures | Reference | Related Articles | Metrics
Analysis and application of the responses of the frequency selection method of telluric electricity field
YANG Tian-Chun, HU Feng-Ming, YU Xi, FU Guo-Hong, LI Jun, YANG Zhui
Geophysical and Geochemical Exploration    2023, 47 (4): 1010-1017.   DOI: 10.11720/wtyht.2023.1424
Abstract103)   HTML1)    PDF (1964KB)(183)      

As an inevitable physical phenomenon in the application of frequency-domain electromagnetics, the static shift effect is generally suppressed or eliminated by correction. This study proposed a new approach of directly utilizing the static shift effect of natural electromagnetic methods to explore shallow electrical anomalies. The frequency selection method of telluric electricity field (FSM) is to study the variations in electrical properties of subsurface media by measuring several horizontal electric field components with different frequencies generated on the surface by the natural alternating electromagnetic field. In this study, the forward modeling of FSM data was conducted using the two-dimensional finite element method. The modeling results are shown as follows: (1) In the case of low-resistivity anomalies near the surface, the curves of horizontal electric field components along the survey line on the surface showed the same morphologies as the FSM-derived curves, with significant low-potential anomalies above the low-resistivity anomalies; (2) As the calculated frequencies increased, both the profile curves and the pseudosection map of electric field components exhibited a static shift effect, indicating that the FSM-derived anomalies were mainly caused by the static shift effect. Both the FSM application results and the drilling verification results showed that with the presence of groundwater, the FSM-derived profile curves and pseudosection map exhibited a significant static shift effect, which was consistent with the CSAMT exploration results. As indicated by theoretical and practical research, it is feasible to directly use the components of the telluric electricity field for the exploration of shallow electrical anomalies. Moreover, shallow geological exploration can be conducted by utilizing the static shift effect of the frequency domain electromagnetics.

Table and Figures | Reference | Related Articles | Metrics
Two-dimensional joint inversion based on the marine controlled-source electromagnetic method and seismic full-waveform
KONG Fan-Xiang, TAN Han-Dong, LIU Jian-Xun
Geophysical and Geochemical Exploration    2024, 48 (1): 67-76.   DOI: 10.11720/wtyht.2024.2583
Abstract103)   HTML1)    PDF (5740KB)(109)      

To reduce the limitations and the multiplicity of solutions of a single geophysical inversion method, this study investigated the two-dimensional joint inversion based on the marine controlled-source electromagnetic (MCSEM) method and seismic full-waveform inversion. The MCSEM method employs the data-space Occam’s algorithm, while the seismic full-waveform inversion utilizes the gradient algorithm. By incorporating a cross-gradient function for the mutual coupling of the two types of physical property parameters, this study developed a two-dimensional joint inversion method, whose accuracy was verified using three different models. As indicated by the results, compared to a single inversion method, the MCSEM-based joint inversion yielded significantly improved inversion results, predominantly in terms of the morphology characterization of anomalous bodies, as well as the reconstruction of their structure and textures and their physical property values. Therefore, the full-waveform inversion can enhance the reliability of the MCSEM inversion results.

Table and Figures | Reference | Related Articles | Metrics
Application of high-density electrical resistivity tomography and audio magnetotellurics for groundwater exploration in the karst area in southwestern China
XIA Shi-Bin, LIAO Guo-Zhong, DENG Guo-Shi, YANG Jian, LI Fu
Geophysical and Geochemical Exploration    2024, 48 (3): 651-659.   DOI: 10.11720/wtyht.2024.1237
Abstract101)   HTML2)    PDF (5894KB)(80)      

Huize County of Yunnan Province is situated in the karst area in southwestern China, where karst groundwater is its primary water source. To conquer local difficulties in drinking water, this study constructed a conceptual model of groundwater occurrence by fully investigating the hydrogeological conditions of the Huize area. Moreover, this study evaluated the applicability and optimal combination of geophysical methods based on the measurement results of petrophysical properties. According to the actual local needs, this study deployed a comprehensive profile combining high-density electrical resistivity tomography (HDERT) and audio magnetotellurics (AMT) in Tuogu Village, Huize County. The groundwater enrichment site was delineated relying on resistivity anomalies, effectively guiding the layout of boreholes. The boreholes achieved the maximum single-borehole water yield of 20.76 m3/d, thus effectively alleviating the local drinking water problem. The HDERT-AMT combined exploration method proves to be optimal for prospecting for groundwater in carbonate rock areas. HDERT can accurately characterize weathered layer thicknesses, bedrock boundaries, fissure evolutionary degrees, and water-bearing properties of strata, constraining groundwater recharge channels, thus counteracting AMT's defects for identification of near-surface stratigraphic structures. AMT can accurately reflect the spatial structures of fracture zones and the macrostructures of strata, limiting the boundary conditions (aquicludes) of water-bearing structures, thus making up for the defects of insufficient detection depths of HDERT in high-resistivity stratigraphic regions. HDERT and AMT, which are complementary to each other in terms of accuracy and depth, can be applied to identify and constrain the spatial occurrence conditions of groundwater migration, storage, and enrichment.

Table and Figures | Reference | Related Articles | Metrics
An integrated data quality evaluation of Earth magnetic anomaly grid EMAG2v3 and global gravimetric database V29: A case study of the Aegir ridge in the Arctic
ZHANG Mian, ZHANG Chun-Guan, ZHAO Min, ZHONG Zhen-Hua, YUAN Bing-Qiang, ZHOU Lei, HAN Mei
Geophysical and Geochemical Exploration    2023, 47 (6): 1410-1416.   DOI: 10.11720/wtyht.2023.1558
Abstract101)   HTML5)    PDF (3654KB)(122)      

To evaluate the qualities of the marine magnetic data in the Earth magnetic anomaly grid EMAG2v3 and the marine gravity data in global gravimetric database V29, this study selected the magnetic and gravity data of the Aegir axial rift and its adjacent areas within a range of about 150 km from EMAG2v3 and V29, respectively to conduct comparative research. This study systematically collected the anomaly data of the study area from EMAG2v3 and V29 for comparison with the measured gravity and magnetic data of the study area. First, this study gridded and whitened the EMAG2v3 data, V29 data, and measured gravity and magnetic anomaly data to obtain the corresponding images. Then, this study analyzed the correlations between the EMAG2v3 data and the shipborne magnetic data and between the V29 data and the shipborne gravity data, obtaining the magnetic and gravity correlation diagrams and corresponding correlation coefficients. By comparing the correlation coefficients and differences between the two kinds of magnetic data and the two kinds of gravity data, this study conducted an integrated evaluation of magnetic the gravity data of the study area from EMAG2v3 and V29, respectively. As indicated by the results, EMAG2v3 incorporates many shipborne magnetic data, with the shipborne magnetic anomaly data showing higher quality than the data from the EMAG2v3 for areas with dense survey lines. The results also show that the shipborne gravity anomalies showed roughly the same variations as those from V29, indicating the same lateral resolution of the two types of anomaly data.

Table and Figures | Reference | Related Articles | Metrics
Geochemical characteristics of fluorine in irrigation water and soils in the Gaomi area, Shandong Province, China
JIANG Bing, LIU Yang, WU Zhen, ZHANG De-Ming, SUN Zeng-Bing, MA Jian
Geophysical and Geochemical Exploration    2023, 47 (5): 1348-1353.   DOI: 10.11720/wtyht.2023.1527
Abstract100)   HTML0)    PDF (1766KB)(183)      

This study aims to ascertain the distribution patterns and influencing factors of fluorine in irrigation water and soils in the Gaomi area, Shandong Province, China. Through systematic sampling and testing, this study obtained data including the pH and fluoride concentration of irrigation water and the pH, organic matter, and fluorine concentration of soils. Based on these data, this study plotted the geochemical contour maps for statistical, correlation, and difference analyses. Furthermore, this study explored the influencing factors. The results are as follows: (1) The irrigation water in the study area has a fluoride concentration of 1.89 mg/L on average, which shows strong spatial variability. Zones with high fluoride concentrations in irrigation water are distributed in the northern low-flat alluvial plain, with the number of samples with fluoride concentrations greater than 2 mg/L accounting for 63.16%. There is a significant positive correlation between the fluoride concentration in the irrigation water and the pH (P < 0.01); (2) The soils have a fluoride concentration of 455×10-6 on average, which shows an inhomogeneous spatial distribution. Zones with high or excess fluorine concentrations are distributed in the northern part of the study area. The fluorine concentrations of soils show significant positive correlations with the pH and organic matter of soils and the fluoride concentration of irrigation water (P < 0.01); (3) The fluoride concentrations in the irrigation water and soils are high in the distribution area of lime concretion black soil. The results of this study reveal the background characteristics and influencing factors of fluoride in the irrigation water and soils of the Gaomi area, providing a geochemical basis for the precise prevention and control of endemic fluorosis.

Table and Figures | Reference | Related Articles | Metrics
Neural network-based denoising for ground-penetrating radar data
WU Song, NING Xiao-Bin, YANG Ting-Wei, JIANG Hong-Liang, LU Chao-Bo, SU Yu-Di
Geophysical and Geochemical Exploration    2023, 47 (5): 1298-1306.   DOI: 10.11720/wtyht.2023.1347
Abstract100)   HTML1)    PDF (6256KB)(206)      

Ground-penetrating radar (GPR) data are often contaminated by random noise in the actual engineering inspection.The noise in data will reduce the signal-to-noise ratio and resolution of the data,adversely affecting the subsequent inversion and interpretation.Accordingly,this study proposed neural network-based denoising for GPR data.First,a multi-layer neural network model was constructed to integrate the data corrupted by white Gaussian noise into the noise-free data.Then,the corrupted data and their corresponding noise patches were built as training data.The weights of neurons in every layer of the model e updated using a back-propagation algorithm to minimize the model training loss.Finally,the two synthetic data and the measured radar data were input to the trained model,and the model's output was calculated using the noise characteristic weights acquired from the training.Compared with the curvelet transform,the numerical simulation test results verify the effectiveness and robustness of the method proposed in this study.Moreover,the proposed method can suppress the noise more thoroughly in areas with complex structures and weak amplitudes,and show effective signals more clearly.

Table and Figures | Reference | Related Articles | Metrics
Distributions of the total concentration, bioavailability, and speciation of selenium in soils in Luoyang City, Henan Province, China
TIAN Qiang-Guo, HOU Jin-Kai, YANG Zai-Wei, LI Li-Yuan
Geophysical and Geochemical Exploration    2023, 47 (5): 1371-1378.   DOI: 10.11720/wtyht.2023.1488
Abstract100)   HTML1)    PDF (2826KB)(140)      

Targeting the selenium resource in soils of Luoyang City, Henan Province, this study analyzed the distribution of total selenium concentration under different geological settings, soil types, land use types, acidity and alkalinity, and organic matter. Furthermore, it determined the bioavailability and speciation distribution of selenium in the soils. The results indicate that: (1) The soils in Luoyang City have total selenium concentrations of (0.03~5.67)×10-6, with an average of 0.30×10-6, and the area of soils with moderate and rich selenium accounts for 94.73%; (2) The average selenium concentration is the highest in soils of the Jixian Yunmengshan formation and the lowest in soils of the Cambrian Xinji Formation; (3) The average total selenium concentration is the highest in lime concretion black soil and the lowest in paddy soil; (4) Regarding land use types, the average total selenium concentration is relatively high in soils of paddy land and woodland; (5) Soils with high acidity and high organic matter concentrations are favorable for selenium enrichment; (6) In terms of soil types, the average concentration of bioavailable selenium is the highest in fluvo-aquic soils and the lowest in red clays; (7) The average concentration of bioavailable selenium is higher in alkaline soils than in neutral and acidic soils; (8) Selenium in soils primarily occurs in residue, strong organic bound, and humic acidic bound forms, with the highest average concentration of bioavailable selenium occurring in alkaline soils and red clays. The selenium resource in the soils in Luoyang City has high utilization potential, and it is feasible to conduct targeted development and planning of the selenium-rich industry according to the distribution of total selenium concentration in the study area.

Table and Figures | Reference | Related Articles | Metrics
Metallogenic prospect prediction and 3D geological modeling for the Tonglyushan ore field
LIU Bao, YANG Yu-Shan, LIU Tian-You
Geophysical and Geochemical Exploration    2023, 47 (4): 906-915.   DOI: 10.11720/wtyht.2023.1398
Abstract99)   HTML1)    PDF (7791KB)(215)      

The Tonglvshan ore field is the most important skarn copper-iron-gold polymetallic ore field in the southeastern Hubei ore concentration area. Since its mineralization is closely related to Tonglvshan stocks, ascertaining the deep distribution and morphologies of these stocks and their contact relationship with surrounding limestones and marbles holds great significance for deep prospecting prediction of the ore field. This study first conducted a detailed analysis of the gravity and magnetic anomaly combinations of the Tonglvshan pluton and stocks; limestones and marbles, as well as their xenoliths; and skarn ore bodies and mineralized bodies. Accordingly, this study inferred the boundary of the Tonglvshan pluton and delineated the xenoliths and mineralized bodies of limestones and marbles within the Tonglvshan pluton. Then, this study conducted the 3D geological modeling based on the results from the 3D physical property inversion and 2.5D and 3D gravity-magnetic human-computer interaction inversion, as well as the drilling and geological data. Finally, this study established a 3D geological model for the plutons and mineralized bodies at depths of 4000 m and below in the Tonglvshan ore field, providing a basis for target delineation and deep prospecting prediction.

Table and Figures | Reference | Related Articles | Metrics
More...
Office Online
News
gfff
More>>
Information
Sponsored by:
China Aero Geophysical Survey and Remote Sensing Center for Natural Resources
Edited by:
Editorial Office of Geophysical and Geochemical Exploration
Add:
29 Xueyuan Road, Beijing 100083,China
Tel: 86-010-62060192/62060193
Fax: 86-010-62060193
Email: whtbjb@sina.com
Web: http://www.wutanyuhuatan.com
Editor in Chief: XIONG ShengQing
Published by:
The Geological Publishing House (31 Xueyuan Road,Beijing 100083,China)
Printer:
Beijing Changning Printing Co. Ltd.
Distributor: Beijing Post Office
Abroad Distributor:
China International Book Trading〖DW〗Corporation
Subscription Hander:
Local Post Offices of China
Links
More>>
京ICP备05055290号-3
Copyright © 2021 Geophysical and Geochemical Exploration, All Rights Reserved.
Tel:(8610)62301569   Email:wt@caict.ac.cn