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  • Table of Content
      10 June 2014, Volume 38 Issue 3 Previous Issue    Next Issue
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    Article
    The application research on the gravity exploration in sedimentary bauxite deposit survey
    Wang Wanyin, Ren Feilong, Wang Yunpeng, Ji Xiaolin, Li Jianguo, Li Qian
    Geophysical and Geochemical Exploration. 2014, (3): 409-416.   DOI: 10.11720/wtyht.2014.3.01
    Abstract   HTML   PDF (4070KB) ( 618 )

    Sedimentary bauxite deposit in the northern part of China mainly locates in the sag of the touching area between Ordovician limestone and Carboniferous Benxi Group. For the reason that there is a density difference between the sides of the above touching region, the target areas can be located by the low bouguer gravity anomaly. However, due to the influence by the observation on undulated surface and by the difficulties in density selection when apply the middle layer and the terrain corrections, the bouguer gravity anomaly may appears several mirroring or positive correlative false anomalies regarding to the topography, which gives troubles to determine the target areas. In order to eliminate or weaken this false anomaly, we obtained a new gravity anomaly by using a potential field on curved surface processing method and a moving window regression analysis method, and reinterpret it. The results show that the false anomalies can be well eliminated in bouguer gravity anomaly by these two methods, and the undulating topography of the above touching area is correctly reflected, and the target areas is accurately determined, which helps to achieve the efficient prospecting purpose.

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    The application of integrated geophysical methods to the prospecting for gold-copper deposits on the periphery and in the depth of Sarsuk area, Xinjiang
    Li Zhongping
    Geophysical and Geochemical Exploration. 2014, (3): 417-422.   DOI: 10.11720/wtyht.2014.3.02
    Abstract   HTML   PDF (2217KB) ( 581 )

    The gold-copper deposit on the periphery of Sarsuk area in Xinjiang is located in the west of the Ashele large-size copper deposit and lies between the Duolanasayi arc-trench interstitial structural belt and the Ashele island arc structural belt which are separated by F6-1 Maerkakuli deep fault. According to the ore-forming regularity and stratigraphic characteristics, the author carried out combinational exploration by using ground high-precision magnetic measurement, IP mid-gradient, IP sounding, CSAMT and TEM and, on the basis of drill hole locating, utilized IP sounding to delineate mineralized bodies at intermediate or shallow depth. Based on studying the corresponding relationship between CSAMT results and IP sounding results at the shallow depth, the author further studied the reflection regularity of CSAMT results for deep mineralized bodies. According to the results of CSAMT method, the sizes and attitude variations of the possibly existent concealed rock bodies, ore-controlling structures and silicification zones can be basically detected so as to provide deep ore-prospecting information. Two drill holes deployed along No. II mineralization-alteration zone on the periphery of Sarsuk area both intersected ore bodies, suggesting that great ore-prospecting potential might exist on the periphery and in the depth of Sarsuk area.

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    The application of gravity and magnetic techniques to the prospecting for the Tuerkubantao copper-nickel ore district
    Wang Wanyin, Feng Xuliang, Gao Lingju, Wang Pengfei, Liu Bin
    Geophysical and Geochemical Exploration. 2014, (3): 423-429.   DOI: 10.11720/wtyht.2014.3.03
    Abstract   HTML   PDF (2988KB) ( 608 )

    On the basis of observed gravity and magnetic data combined with geological information and borehole data obtained in the Tuerkubantao Cu-Ni ore district,the authors determined high gravity anomalies along with high magnetic anomalies as symbols to recognize ultrabasic rocks and basic rocks in this area. The authors used the correlation analytical method to analyze gravity and magnetic anomalies and,through computation of the correlation coefficient of gravity and magnetic anomalies,found that they are obviously of consanguinity. The authors deduced five faults with the edge recognition technology based on the normalized vertical derivative of the total horizontal derivative(NVDT_THDR) for potential field data. It is shown that the NWW—SEE trending faults were formed earlier and they are in accord with regional structure trend. The NE—SW trending faults were formed later and disconnected the NWW—SEE trending faults. 18 ultrabasic rocks and basic rocks were recognized based on the second order vertical derivative of Bouguer gravity anomalies,the first order vertical derivative of magnetic anomalies reduced to the pole and the result of correlation analysis. Then a discussion was made on the plane distribution characteristics and the size of these rocks. Their vertical distribution characteristics and size were also studied by using the gravity and magnetic man-computer interactive joint inversion method. The results indicate that the sizes of the ultrabasic rocks and basic rocks are not big. In consideration of both the characteristics of the faults and the rocks,the authors hold that distribution of the rocks is controlled by faults. The ultrabasic rocks and basic rocks are mainly distributed in the area surrounded by F1 fault,F4 fault and F5 fault. The distribution of the rocks can be divided into three stripes which coincide with the NWW—SEE trending faults. It is thought that the rocks intruded along the NWW—SEE trending faults and were constrained by NE—SW trending faults.

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    The radioactive characteristics of a bauxite deposit in northwestern Henan province
    Wang Mingming, Yang Yong-qian, Ma kai, Zhang Lin, Liang Tao
    Geophysical and Geochemical Exploration. 2014, (3): 430-433.   DOI: 10.11720/wtyht.2014.3.04
    Abstract   HTML   PDF (950KB) ( 400 )

    For evaluating radioactivity of the deposit in the study area and studying the feasibility of applying the radioactive method, the authors measured the γ radiation dose rate of rocks and ores. Statistics show that the γ radiation dose rates of the bauxite vary in the range of (15.53~48.01)×10-9 (C/kg)/h, with the average value being 24.37×10-9 (C/kg)/h, whereas the γ radiation dose rates of other rocks and ores vary between 4×10-9 (C/kg)/h and 8×10-9 (C/kg)/h, suggesting that the bauxite has the strongest radiation in the deposit, which, however, is still much lower than the rated value of evaluation of human hygiene. It is considered that radioactive characteristics of China’s sedimentary bauxite deposits in ancient weathering crusts resemble the characteristics of this deposit, and that the significant difference between bauxite and other rocks provides the physical condition for applying the radioactive method to exploring bauxite deposits.

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    Geochemical characteristics of primary halos and ore-search prospecting in the depth of the Zijinshan copper-gold deposit, Fujian province
    Liu Guangyong, Dai Maochang, Qi Jinping, Zhang Jinzhang
    Geophysical and Geochemical Exploration. 2014, (3): 434-440.   DOI: 10.11720/wtyht.2014.3.05
    Abstract   HTML   PDF (2162KB) ( 580 )

    Based on systematic collection of rock and ore samples from 41 drill holes along No. 4 and No.11 exploration lines in the Zijinshan copper-gold deposit of Fujian Province,the authors drew a contour map of primary halos,established vertical element zoning sequence and orebody denudation guidelines and, in combination with characteristics of the indicator elements in the depth,made a prediction of concealed orebodies.For gold orebody, the near-halo is Au-Ag-Zn1, and the rear halo is Bi-Ga-Mo-Sn-Ti-Co-Ni-W1-V, whereas for copper orebody, the front halo is Hg-Sb-As, the near halo is Cu-Pb1-Zn2, and the rear halo is Be-W2. The evaluation of the denudation of the orebody shows that the high-sulfur copper orebody pinches out to the depth. The abnormal morphology and elemental composition of F-Mn-Pb2-Zn3 in the depth is consistent with the characteristics of a typical porphyry deposit, the porphyry body extends to the periphery of the deposit, and the deep alteration mineral assemblages, metal mineral assemblages, fluid inclusion characteristics show that there may exist a porphyry Cu (Mo) deposit in the depth of the southwest part.

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    The application of geological CHIM method to the prospecting for concealed uranium-lead-zinc deposits in vocanic rock areas
    Li Shizhu, Luo Xianrong, Tang Zhixiang, Li Yiyang, Li Bihong, Zhao Zheng
    Geophysical and Geochemical Exploration. 2014, (3): 441-446.   DOI: 10.11720/wtyht.2014.3.06
    Abstract   HTML   PDF (6818KB) ( 341 )

    It has been observed that the geological CHIM method is effective in search for concealed uranium deposits in volcanic rock areas. On such a basis, a geological CHIM comprehensive model was established through a comprehensive analysis and study of anomalous and metallogenic geological settings. The model could be used to look for orebodies in the peripheral areas. As a result, 7 targets were delineated.

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    Geochemical characteristics of a copper-lead-zinc-barite deposit in Guangxi and their geological implications
    He Shenghui, Rong Huifeng, Chen Xiansheng
    Geophysical and Geochemical Exploration. 2014, (3): 447-452.   DOI: 10.11720/wtyht.2014.3.07
    Abstract   HTML   PDF (2650KB) ( 322 )

    Based on the data of lithogeochemistry and isotope geochemistry, the authors studied geological characteristics,genesis and metallogenic epoch of a certain copper-lead-zinc-barite deposit in Xiangzhou County of Guangxi. Some conclusions have been reached: mineralization of the ore district was controlled by the structural fracturing zone; sulfur in the barite resulted from sea and gypsum-salt of Devonian period; the source beds of copper, lead, zinc and barium were mainly Devonian strata and subordinately deep magma; the ore-bearing solution was hot brine from underground deep cycle water; the metallogenic temperature was about 170℃; the copper-lead-zinc-barite deposit was a mesothermal-epithermal deposit; the metallogenic epoch was early Indosinian-early Yanshanian period. The results obtained by the authors lay the foundation for the further geological exploration.

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    Geochemical characteristics of Pingran area in Laos based on stream sediment survey and their prospecting signifivance
    Lei Chuanyang, Li Ruifeng, Zhao Baoshun, Zhao Guiqiu
    Geophysical and Geochemical Exploration. 2014, (3): 453-460.   DOI: 10.11720/wtyht.2014.3.08
    Abstract   HTML   PDF (1064KB) ( 368 )

    Pingran area is located in the Ma Jiang-Xam Nua island arc metallogenic belt, and the metallogenic condition of magmatic copper-nickel sulfide deposits is excellent. 1:50 000 stream sediment survey around the Pingran area of Laos revealed an anomaly combination of multiple elements dominated by Cu, Ni and Co accompanied by Cr, V and Ti, reflecting the metallogenic specialization of the basic-ultrabasic rocks. The authors used the method of factor analysis and clustering to analyze the data of 1:50000 stream sediment survey in Pingran area,and made a geological interpretation of the deposit. It is suggested that the anomalies from the geochemical survey are associated with the mineralization along a series of NW-trending fracture zones and the basic-ultrabasic rocks. Cluster analysis of the stream sediment geochemical data of Pingran area shows that fifteen kinds of trace elements can be grouped into three types,i.e. Ni, Cr, Cu, V, Co, Zn and Ti belong to the first type,As, Sb and Pb to the second type,and the rest to the third type. The first type reflects elemental distribution, accumulation characteristics and related mineralization information of mafic-ultramafic rocks,whereas the second type reflects the combination of ore-forming elements at low-medium temperature. The primary factor of stream sediment geochemical element F1 may represent Cu, Ni and Co mineralization of mafic-ultramafic rocks. There are 607 samples with the factor F1 scores higher than 2 among all the 3806 samples from Pingran area. Distribution characteristics of the factor F1 score anomalies are roughly consistent with those of Au,As and Cu anomalies in Pingran area. Thus,the overlapped portion between the Cu, Ni and Co anomaly area and the area where factor F1 scores are higher than 2 should be the key ore-prospecting target dominated by Cu, Ni and Co.

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    The application of integrated geophysical methods to the geothermal exploration in Shenxian area
    Ma Xiaodong, Liu Hongbo, Bai Jinline
    Geophysical and Geochemical Exploration. 2014, (3): 461-464.   DOI: 10.11720/wtyht.2014.3.09
    Abstract   HTML   PDF (732KB) ( 505 )

    As Shenxian area is extensively covered by Cenozoic strata of rather great thickness, the prospecting for geothermal resources should find out the characteristics of thermal reservoir bed, cover bed and faulted structure. In this area, the CSAMT has a good transverse capability of distinguishing faulted structures, and the direct current electric sounding can yield fairly good result in distinguishing Cenozoic strata. Based on collecting relevant geological, seismic and logging data, the authors made geological integrated inference, with the direct current sounding semi-quantitative interpretation result as the constraint condition of the CSAMT quantitative interpretation. As a result, the buried depth and distribution of the deep concealed strata, thermal reservoir beds and faulted structures were basically detected, with good survey result obtained. It is held that the integrated application of two geophysical methods can yield results with high quality and high effectiveness in the early-stage exploration of geothermal resources.

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    An analysis of grativity anomalies in the ore concentration areas of Guangdong province
    Chen Ming
    Geophysical and Geochemical Exploration. 2014, (3): 465-470.   DOI: 10.11720/wtyht.2014.3.10
    Abstract   HTML   PDF (6889KB) ( 291 )

    The metallogenic geological setting of the ore concentration area was related to the crustal deformation during the Paleoproterozoic geological evolution of the crust and the substance migration under the chemical action. The intrusive rocks in Guangdong caused a variety of geological processes, and were associated with the formation of various metal deposits. In order to study the relationship between magmatic rocks and mineralization, the authors used gravity data to analyze the distribution of intrusive rocks and revealed that the residual gravity anomaly resulted from the reaction of magmatic rocks. It is held that, using multi-scale wavelet decomposition approach, we can analyze the spatial distribution of intrusive rocks and the intrusive path to sum up the gravity field characteristics of the ore concentration area and, in combination with geological knowledge, we can eventually predict the the ore concentration area.

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    The combination of geochemical exploration methods and the prospecting breakthrough in the northern Dahinggan Ling metallogenic belt
    Zhao Pizhong, Cheng Zhengfa, Zhou Erbin, Tu Jinfei, Sheng Xia
    Geophysical and Geochemical Exploration. 2014, (3): 471-477.   DOI: 10.11720/wtyht.2014.3.11
    Abstract   HTML   PDF (8562KB) ( 398 )

    The Da Hinggan Mountains metallogenic belt is one of the most important base metal mineralized zones in China. Mineral exploration, however, is very difficult in the northern part because of forest and swamp cover. The authors first selected the potential targets by data processing and interpretation of 1:20000 regional geochemical anomalies. Detailed soil survey clearly indicates that there might be some economic base ore bodies in the regional geochemical targets. The innovatory high density rock chip survey successfully defined the dimension of the mineralizations. The Shangkenguo superlarge Pb-Zn deposit was found after trenching and drilling the geochemical anomalies. The geochemical methods and idea resulting in successful discovery can be an example of mineral exploration in the forest and swamp landscape.

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    The radioactive elements content of natual fluorite and its influence
    Zou Hao, Zhang Shouting, Fang Yi, Chen Anqing, Gao Feng, Tang Li, Deng Mingzhe
    Geophysical and Geochemical Exploration. 2014, (3): 478-484.   DOI: 10.11720/wtyht.2014.3.12
    Abstract   HTML   PDF (1890KB) ( 519 )

    whether fluorite radioactivity affects human health or not, in view of such a situation, the authors used gamma spectrometer to measure the fluorite radioactivity in different host rocks in five representative fluorite ore districts which are distributed respectively in Zhejiang, Inner Mongolia and Chongqing. The results show that, no matter where the fluorite occurs, i.e., whether it occurs in magmatic rocks, metamorphic rocks or sedimentary rocks, the radioactive elements content of fluorite is all by far lower than that of the host rocks. Radioactive elements content of natural fluorite is very low, and the result by using the formula to calculate shows that its radioactive value is much lower than the radioactive limit prescribed by the state. Therefore, except for a small amount of violet black fluorite associated with uranium deposits, the vast majority of natural fluorites cause no harm to human health.

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    A study of influencing factors of diurnal variation of the soil radon concentration
    Wang Dong, Fang Fang, Ding Weicheng, Shi Hui
    Geophysical and Geochemical Exploration. 2014, (3): 485-489.   DOI: 10.11720/wtyht.2014.3.13
    Abstract   HTML   PDF (649KB) ( 418 )

    Surface soil radon could reflect deep underground hydrology, geology, mineral resources, heat source and other information, but the soil radon concentration has diurnal and annual variation characteristics. In order to study this problem, the authors used α spectroscopic cumulative radon instrument for continuous measurement. The results show that the law of soil radon concentration diurnal variation is of the single-peak type, the maximum value appears at the time interval of 19:00-22:00, with the minimum value at 11:00-14:00. Soil temperature is the key factor affecting the soil radon concentration, which is positively correlated with soil temperature. Rainfall has significant effects on soil radon concentration, which assumes double peak type after rain. The changes are related to meteorological factors such as soil humidity and air temperature.

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    The magnetic susceptibility features of rocks and ores in central inner Mongolia
    Wu Chengping, Wang Weiping, Xiao Gangyi, Liu Huanlin
    Geophysical and Geochemical Exploration. 2014, (3): 490-496.   DOI: 10.11720/wtyht.2014.3.14
    Abstract   HTML   PDF (2055KB) ( 548 )

    In order to understand the magnetic features of rocks and ores in the region of Xilin Hot and Bairin Left Banner of inner Mongolia, the authors made integrated interpretation of the aeromagnetic anomalies in this area by using ZH-1susceptibility meter designed and developed by China Aero Geophysical Survey and Remote-Sensing Center for Land and Resources. The magnetic susceptibilities of rocks and ores were measured four times in central Inner Mongolia during 2009 to 2011. Based on the statistics and analysis of the actual measured data of magnetic susceptibilities, the authors studied the distribution of magnetic susceptibilities of rocks and ores in this area, and described the magnetic susceptibility features of sedimentary rocks, intrusive rocks, volcanic rocks, metamorphic rocks, ores and wall rocks, and dealt with the relationship between magnetic susceptibilities and aeromagnetic anomalies as well as the relationship between magnetic susceptibilities and ferromagnetic minerals. The results obtained are important for interpretation of magnetic exploration and geological prospecting.

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    Characterization and evaluation of fracture-cavity type carbonate reservoir in the western part of Northern Tarim uplift
    Zhang Junlin, Tian Shicheng, Zheng Duoming
    Geophysical and Geochemical Exploration. 2014, (3): 497-503.   DOI: 10.11720/wtyht.2014.3.15
    Abstract   HTML   PDF (1829KB) ( 186 )
    Fracture-cavity type carbonatite reservoir has strong dimensional anisotropism, and hence reservoir characterization and evaluation are very difficult. The plateau facies carbonatite fracture-cavity reservoir is stably developed in Middle Ordovician strata in western W block of northern Tarim uplift. Utilizing paleo-geographic coordinate transform, logging reservoir analysis and sensibility attributor analysis of the fracture-cavity type carbonatite reservoir, the authors studied the reservoir facies. Based on reservoir facies research and utilizing stochastic method, the authors built the dual porosity model for fracture-cavity reservoir, and characterized the carbonatite reservoir. Finally, in combination with AVO inversion and reservoir characterization, the carbonatite reservoir was evaluated. It is proved that the reservoir pattern in the study area is mainly of the fracture and cavity type, with fractures acting both as hydrocarbon accumulation space and as the factor for the formation of cavity. AFE (Automatic Fault Extraction) and wave classification attribution were sensitive to the fracture and cavity type reservoir. With increasing oil saturation, AVO of the reservoir became more obvious. The fluid prediction method based on pre-stack AVO inversion could reasonably forecast oil province of carbonnate reservoir.
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    The application of three-component scattering wave seismic imaging in detecting city active fault in Ji district,Tianjin city
    Zhang Baowei, Shen Hongyan
    Geophysical and Geochemical Exploration. 2014, (3): 504-509.   DOI: 10.11720/wtyht.2014.3.16
    Abstract   HTML   PDF (2144KB) ( 350 )
    Three-component (3C) seismic technology to fine solve the near-surface geological problems has obvious advantages. Based on the point scattering seismic-geological model, we deduced multi-component scattering wave time-distance equation. On the basis of establishing the multi-component scattering wave imaging principle, we processed the 3C seismic data for the detecting city active fault in Jixian of Tianjin. Imaging results show that the wave group characteristics of the bedrock surface are obvious, insider structural features are rich, and minor faults near the bedrock surface are more development. Through this study, the contact relationship between the bedrock and Quaternary soil in the region is basic cleared, and the piedmont fault conditions and the geological structure of bedrock near the surface have been clear surveyed.
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    A study of the key seismic acquisition technology in the salt marsh area of Dulan,Qinhai province
    Zhang Zhilin, Liu Bin, He Jingguo, Gao Lulu, Liu Lijuan, Sun Li
    Geophysical and Geochemical Exploration. 2014, (3): 510-515.   DOI: 10.11720/wtyht.2014.3.17
    Abstract   HTML   PDF (2655KB) ( 304 )
    It is very difficult to conduct seismic acquisition in Dulan,because it has a lot of salt ponds and salt lakes on the surface and extensive thick crystalline interbeds in the near-surface area. In this paper, the authors analyzed in detail the seismic response characteristics of the near-surface media in Dulan, with the emphasis placed on the characteristics of crystalline interbedded strata and beaded cavities by means of a model. Through the application of the actual seismic data, it is confirmed that the near-surface absorption decay law of the crystalline interbedded strata is correct. Moreover,the authors investigated the optimization techniques for the acquisition technology series by analyzing the stratification near the surface, and also optimized the depth design and the variable concept of the observation system. As a result, good results in the actual acquisition applications were acquired, and the problems concerning complex salt marsh area acquisition were successfully solved.
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    The calculation of full time apparent resistivity for transient electromagnetic survey based on “double smoking ring” theory
    Xu Yangcheng, Wu Yan-qing, CUI Ren, HAN Shuang
    Geophysical and Geochemical Exploration. 2014, (3): 516-521.   DOI: 10.11720/wtyht.2014.3.18
    Abstract   HTML   PDF (988KB) ( 326 )
    Owing to the impact of inductor and capacitor of transmit coil, the transmit current of transient electromagnetic turns off like the ramp current. If we use the "single smoke ring" theory which fits for step turning off transmit current to make interpretation, the distortion will occur during the early and middle stage. According to the expression of second field induced voltage for ramp current, this paper presents interpretation with the "double smoke ring" theory, i.e., the secondary field induced voltage is made to be equivalent to the summation of secondary magnetic induction excited by two equal, opposite and successive "smoke ring" after the current is completely turned off. The secondary magnetic induction excited by every "single smoke ring" is calculated with forward and backward recurrence respectively. After that, the monotony of secondary magnetic induction excited by "smoke ring" is utilized to calculate the full-time apparent resistivity of ramp current and remove the distortion. At last, the numerical simulation model is used to confirm the correctness. The results obtained by the authors provide theoretical support for the full-time transient electromagnetic exploration and explanation.
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    The test of high-density induced polarization technique in the detection of shallow concealed lead-zinc deposits
    Zhang Wei, Zhang Zhen, Li Hua, Yu Yuanshan, Jiao Yanjie
    Geophysical and Geochemical Exploration. 2014, (3): 522-526.   DOI: 10.11720/wtyht.2014.3.19
    Abstract   HTML   PDF (1079KB) ( 465 )

    The application of Chinese-made WGMD-9 super-high-density electrical system to the Yangtianwo lead-zinc ore district in Shuicheng of Guizhou Province shows that this technique can more accurately distinguish the electrical structure characteristics of the Upper Permian Liangshan Formation and the Upper Carboniferous Maping Formation which are closely related to mineralization, and can also more accurately detect the orebody buried in the contact area between the sandstone and shale of Liangshan Formation and the limestone of the Maping Formation in the depth of 0~150 m, thus guiding the implementation of surface prospecting tunnels and finally achieving the prospecting aim through "indirect" means. The results obtained also show that the high-density induced polarization technique has two deficiencies, i.e., the restriction of supply current and the limited depth of detection.

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    An analysis of noise effect on the identification of sources of potential fields with the continuous wavelet transform method and the choice of the scaling factor
    Liu Caiyun, Yao Changli
    Geophysical and Geochemical Exploration. 2014, (3): 527-533.   DOI: 10.11720/wtyht.2014.3.20
    Abstract   HTML   PDF (1091KB) ( 233 )

    In order to improve the accuracy of the identification of sources of potential fields with the continuous wavelet transform method (CWT), this paper deals with the effect of noise and the choice of scaling factor. Firstly, the principle of the identification of sources of potential fields with the CWT method is presented. Secondly, the method is used to identify the sources from potential field data with noise of various levels, and the effect of noise is analyzed. Lastly, the effect of suppressing noise by CWT is analyzed, and the choice of scaling factor is studied. The results of identification of the sources of synthetic data and field data indicate that the noise can decrease the accuracy of identification result. but the choice of the scaling factor can suppress the noise and improve the accuracy of the identification result.

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    The analytical calculation of the angle domain topographic point-source electric field and its application to high density resistivity method for topographic correction
    Xu Zhimin, Zan Chongxin, Xiao Xiao, Li Jin, Xin Huicui
    Geophysical and Geochemical Exploration. 2014, (3): 534-538.   DOI: 10.11720/wtyht.2014.3.21
    Abstract   HTML   PDF (2249KB) ( 373 )

    With the angle domain overlay method, the apparent resistivity anomaly produced on pure landform was obtained; by adopting the ratio method, topographic correction was made for high density resistivity measuring data under the condition of slope topography; in combination with the drill hole geological sections in the surveying area, the effects of the topographic correction were analyzed. The results show that the method of angle domain topographic correction is effective, as is shown by the facts that the inverse sectional drawing after the topographic correction is closer to the practical geological situation, and the effects are fairly satisfactory.

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    Systematical improvements of trace gold field rapid determination method
    Zhou Yuguo, Gao Qizhi, Wang Yuchao, Zhou Kun
    Geophysical and Geochemical Exploration. 2014, (3): 539-543.   DOI: 10.11720/wtyht.2014.3.22
    Abstract   HTML   PDF (2272KB) ( 364 )

    Based on analysis experience for several years of more than 10000 samples with various content of gold from different gold deposits or gold survey areas, this paper brings forward systematical improvements of trace gold field rapid determination method, involved less operation processes, available and portable devises, by which, high speed and efficiency can be obtained without loss of precision and accuracy. According to Qeqott formula, combined with acquaintance of (super-) micro-fine gold deposits, proposes a solution to sample wight of trace gold field rapid determination, thus, the field rapid determination method can be applied to trace gold as well as exploration and development of target deposit.

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    A comparative study of surface wave dispersion curves extracted from S transform and wavelet transform based on multi-mode separation
    Lin Dandan, Xiong Zhangqiang, Zhang Dazhou
    Geophysical and Geochemical Exploration. 2014, (3): 544-551.   DOI: 10.11720/wtyht.2014.3.23
    Abstract   HTML   PDF (3259KB) ( 450 )

    To compare and analyze the dispersion accuracy of Rayleigh wave calculated by wavelet transform and S transform, the authors applied staggered grid high-order finite difference method to two-layer model and six-layer model designed by the authors, then the Rayleigh wave records of different modes in time-space domain were isolated by using F-K method, and Rayleigh wave dispersion curves of different modes were calculated by using wavelet transform and S transform in comparison with the theoretical values. Finally, the two methods were used to deal with real data. The results shows that the error in the low frequency of the dispersion curve calculated by wavelet transform is relatively large and the accuracy of the dispersion curve calculated by S transform is higher than that calculated by wavelet transform on the whole.

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    A study of encoding and decoding method in active seismic source exploration
    Tang Jie, Xiao Guangrui, Fang Bin
    Geophysical and Geochemical Exploration. 2014, (3): 552-557.   DOI: 10.11720/wtyht.2014.3.24
    Abstract   HTML   PDF (823KB) ( 258 )

    According to the repeatability and controllability of artificial active source, encoding seismic source can be used effectively to improve the capability of artificial source exploration depth and detection distance. In this paper, the authors studied the encoding and decoding method of active seismic source exploration, and mainly did the following work: ① the analysis of the basic principles of encoding seismic source. The coded method can increase the range of the target and reduce side-lobe energy with correlation; ② the study of three source encoding methods, and make the comparison. The authors have designed coded source which can be fired repeatedly in different time intervals with different energies, and coded seismic source can reduce autocorrelation side-lobes. Signals can be detected with better sensitivity in the time interval after the first autocorrelation peak and before the first periodic side-lobe; ③ the study of the principle of iterative correlation method for decoding. The encoding method can significantly improve the seismic exploration capability. It is proved that researchers can obtain a large detection range and high resolution using encoding method with small energy source.

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    The application of colored inversion to reservoir prediction in sparse well zone
    Bi Junfeng, Yang Peijie
    Geophysical and Geochemical Exploration. 2014, (3): 558-565.   DOI: 10.11720/wtyht.2014.3.25
    Abstract   HTML   PDF (4607KB) ( 596 )

    Every inversion method has its own characteristics and applicable conditions. The inversion based on model can obtain high resolution in vertical and horizontal direction, but the inversion result is affected obviously by wells and wavelet. So it can be used to interpret lithologic body in multiple wells area. Colored inversion is a kind of frequency domain inversion method, which does not depend on initial model and needs limited wells. Moreover, the inversion result is faithful to seismic data and the inversion process is relatively simple. By building forward model and testing parameter, the authors got to know the physical meaning and range of inversion parameters. By using this method, the authors preferably depicted the lateral distribution characteristics of fan body in lower Es3 of Gunan sag. Compared with conventional seismic attributes, the colored inversion results are more coincident with the deposition rules and the lithologic distribution of the actual drilling wells. It is shown that the colored inversion method could improve the resolution of seismic data based on keeping the original phenomena, and hence it is suitable to interpreting the strata or lithologic characteristics in sparse or no well zone.

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    The analysis and application of multiple wave forward modeling and the influencing factors of SRME technology
    Jin Mingxia, Yi Shuchang, Wang Zheng
    Geophysical and Geochemical Exploration. 2014, (3): 566-570.   DOI: 10.11720/wtyht.2014.3.26
    Abstract   HTML   PDF (2072KB) ( 303 )

    Heavy multiple waves in marine seismic exploration interfered by primary waves can't be fully attenuated, and these multiple waves make the seismic profile too illegible and also makes it difficult to easily interpret and trace the horizon. In view of such a situation, multiple wave forward modeling by simulating field operation on the given velocity horizon model was created. As there were only a few horizons in the mocked layer model, some factors such as sample in pace and extended radius that affected precise prediction of multiple wave model were analyzed and discussed. After that, reasonable processing parameters were optimized and applied to the real seismic data. The final results demonstrate that 3D SRME (Surface Related Multiple Elimination), which is better than 2D SRME, is capable of effectively suppressing multiple waves.

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    A study of inverse Q continuation operator in dual complexity media
    Guo Kai, Lou Tingting
    Geophysical and Geochemical Exploration. 2014, (3): 571-576.   DOI: 10.11720/wtyht.2014.3.27
    Abstract   HTML   PDF (2072KB) ( 223 )

    Inelastic attenuation characteristics of the layers cause the narrowness of middle and deep signal band, weakness of energy, and difficulty of imaging. It is therefore necessary to compensate the inelastic attenuation of the layers. Based on one-way wave equation, the authors use the complex velocity including quality factor and frequency substitutes for real velocity. Then through expansion viscous continuation operators using continued fraction in F-X domain, the authors obtain phase and compensate term, correct the error caused by continued fraction in F-K domain, and use gradually accumulate method to solve the irregular surface problem. This method could improve the imaging accuracy and compensate the amplitude and frequency attenuation effectively. Model trial and real data processing show that this method has certain adaptability and practicability.

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    The absorption compensation research based on viscolasti acoustic wave equation
    Guo Jianle
    Geophysical and Geochemical Exploration. 2014, (3): 577-581.   DOI: 10.11720/wtyht.2014.3.28
    Abstract   HTML   PDF (1747KB) ( 544 )

    Generally, the layer medium are viscous.Due to absorption affect, seismic wave energy,especially high- frequency energy be absorbed and attenuated in downward propagation, reflection wave signal frequency bands be narrowed. For compensated those absorbed energy, the paper, adopt viscosity wave equation wave field continuation method, used to carry out energy compensation researching, and obtained better effect. At first, the paper from viscosity wave equation wave field continuation function theory, derived wave field continuation function stability condition;Secondly,author test the method availability;Finally, through forward simulation test, proved absorption and compensation method based on viscosity wave equation can carry on very well compensation of energy attenuation, improved processing effect.

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    The application of the comprehensive static correction technology in complex areas
    Bai Xuming, Cui Hongliang, Yuan Shenghui, Liu Jiangtao, Cheng Zhanzhan, Hu Qing
    Geophysical and Geochemical Exploration. 2014, (3): 582-586.   DOI: 10.11720/wtyht.2014.3.29
    Abstract   HTML   PDF (4575KB) ( 281 )

    Surface velocity and thickness show heterogeneity in complex areas. With the increasingly deep exploration and the complexity of the surveyed areas, static correction problems become more and more prominent and even seriously trouble the seismic acquisition. In order to greatly improve the data quality and imaging precision in the complex seismic exploration areas and meet the needs of the fine oil and gas accumulation exploration in these complex exploration areas characterized by multiple solutions of the surface structure, serious surface adsorption attenuation, low S/N ratios and resolutions and difficult imaging, the authors carried out detailed studies of the statics method based on the FBT of a single source, performed the high and low frequency static separation and integrated the static correction technology. The application of the statics technology shows that S/N can be greatly improved, and good imaging effects can be obtained. The technology can solve not only short wavelength problems but also the long wavelengths problem, thus achieving good exploration results.

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    The extraction of sounding curves from the data of high-density resistivity method for intepretation
    Li Wangming, Wu Shulai, Yi Qiang, Ye Mingjin, Li Jingkai
    Geophysical and Geochemical Exploration. 2014, (3): 587-590.   DOI: 10.11720/wtyht.2014.3.30
    Abstract   HTML   PDF (2590KB) ( 470 )

    For multilayer karst, the caves are rather small or the karst is developed along the bedding, and hence it is difficult to distinguish them directly from the cross-sectional view of the high-density resistivity method. By utilizing sounding curves extracted from high density electrical data and analyzing synthesized sounding curves as well as a cross-sectional view, different kinds of karst can be effectively distinguished. Engineering practice shows that the extraction of sounding curves from the data of high-density resistivity method for interpration can result in fairly good geological interpretation results.

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    The low resistivity abnormal intersection method for transient electromagnetic coalface detection of mine
    Liang Qinghua
    Geophysical and Geochemical Exploration. 2014, (3): 591-594.   DOI: 10.11720/wtyht.2014.3.31
    Abstract   HTML   PDF (1566KB) ( 245 )

    Based on the mine transient electromagnetic detection theory in combination with underground transient electromagnetic detection test, the authors studied the roadway influence and detection method of coalface detection by using mine transient electromagnetic method and put forward the "intersection method"for mine transient electromagnetic coalface detection, i.e., in downhole practical exploration, two adits should be dug for coalface. This method was tested in a coal mine in Luliang of Shanxi Province, and the result shows that the "intersection method" can make more accurate detection, improve the detection accuracy and reduce the drilling workload. This is a reliable method for mine transient electromagnetic detection of coalface. It is thus held that the use of this method should be promoted in the coal mine.

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    The generation and application of geological patterns
    Qiu Chongtao, Quan Xudong, Guo Xinhong, Qin Jinchao, Zi Yong, Wu Yongqiang
    Geophysical and Geochemical Exploration. 2014, (3): 595-600.   DOI: 10.11720/wtyht.2014.3.32
    Abstract   HTML   PDF (1602KB) ( 530 )

    Aimed at solving the problem of the lack of geological pattern design in such software as CorelDRAW, Surfer and Grapher,the authors, based on the spatial distribution regularity of geological patterns, put forward an automation method for producing patterns using Visual Basic 2010 in CorelDRAW X4. Such features as size, density and color in the produced patterns can be adjusted according to the need of the mapping. The patterns are used for drawing in such software as CorelDRAW, Surfer and Grapher.

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    The multi-core paralleled strategies and efficiency analysis of 3D magnetotelluric forward modeling and inversion
    Gu Guanwen, Wu Wenli, Liang Meng
    Geophysical and Geochemical Exploration. 2014, (3): 601-606.   DOI: 10.11720/wtyht.2014.3.33
    Abstract   HTML   PDF (1209KB) ( 313 )

    A parallel magnetotelluric (MT) 3D forward modeling algorithm was implemented on multi-core CPU, and was introduced into the 3D conjugate gradient (CG) inversion algorithm with MT data for parallel computation. The authors tested the parallel MT 3D forward modeling code with a theoretical model and the parallel 3D inversion code with one synthetic data. A comparison of the execution efficiency was made between serial computation and parallel computation. The results indicate that the parallel 3D forward modeling and inversion computation are correct, and the efficiency of computation is greatly improved.

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    The development of airborne geophysical map frame drawing software based on MapGIS K9
    Wu Gaowei, Yan Hongyu
    Geophysical and Geochemical Exploration. 2014, (3): 607-609.   DOI: 10.11720/wtyht.2014.3.34
    Abstract   HTML   PDF (1037KB) ( 425 )

    Through analyzing the existing drawbacks of MapGIS built-in frame drawing function and airborne geophysical map frame constitution, the authors developed airborne geophysical map frame drawing software using C# language and secondary development interface of MapGIS K9. Practical applications indicate that the software can quickly and conveniently draw different kinds of frames, thus effectively improving the working efficiency. Because the database of frame element style is maintainable and extensible, the user can customize the software according to the actual need.

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    The application of integrated geophysical techniques to the investigation of karst graound collapse and ground subsidence in Jingshazhou area, Guangzhou city
    Hu Rangquan, Huang Jianmin
    Geophysical and Geochemical Exploration. 2014, (3): 610-615.   DOI: 10.11720/wtyht.2014.3.35
    Abstract   HTML   PDF (2128KB) ( 486 )

    With the comprehensive use of cross-hole seismic CT technique, ground penetration radar, high density resistivity method, shallow seismic reflection wave method, soil radon concentration and bore wave velocity test method,the authors detected geological hazards of karst ground collapse and ground subsidence in Jinshazhou area, Baiyun district of Guangzhou city. The distribution of karst caves, soil caves and tectonic fracture zones was detected. The authors utilized all kinds of methods and techniques and summarized the results of integrated geophysical techniques. With practical examples, it is proved that integrated geophysical techniques are efficient in the investigation of karst ground collapse and ground subsidence geological hazards, and can provide important basic data for geological disaster prevention. The first cross-hole seismic CT was applied to detecting the distribution of structures of underground karst in Guanghua basin, thus providing a basis for the safety of structures which are affected by karst geological hazards.

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    The application of the surface nuclear magnetic resonance method to detecting Yangtai landslides in Anhui province
    Pan Guolin, Lu Lin, Nie Donggang
    Geophysical and Geochemical Exploration. 2014, (3): 616-619,623.   DOI: 10.11720/wtyht.2014.3.36
    Abstract   HTML   PDF (1817KB) ( 621 )

    In geological field, the NMR method is the unique method for direct detection of groundwater. Using NMR method,we can calculate such hydrogeological parameters of landslides as the water content, the porosity and the permeability coefficient. In this paper, a typical landslide is selected for investigation and drilling verification so as to study the effectiveness, superiority and practicability of the method in landslide application.

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    The application of high-precision magnetic survey to the idantification of interference source of the Xsens system of animation equipment
    Zhang Zuohong, Gao Shiyin, Dai Kangming
    Geophysical and Geochemical Exploration. 2014, (3): 620-623.   DOI: 10.11720/wtyht.2014.3.37
    Abstract   HTML   PDF (1500KB) ( 204 )

    In order to find out whether there exists the magnetic interference source affecting the photographic quality of the Xsens system for capture of inertial motion or not in the new planning area of a digital company in Suzhou, the authors accurately judged that the No. 2 studio had a magnetic interference source by using the measurement result of magnetic field with different probe-heights flexibly applied in the existing studio. With this method, the authors measured the magnetic field of the new planning area and inferred that the intensity of the magnetic field of the new planning area is not enough to cause interference to the Xsens system, which was confirmed by the test.

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    The application of ground-penetrating dadar to the karst foundation investigation
    Liu Wangfeng, Zhang Zhenyong
    Geophysical and Geochemical Exploration. 2014, (3): 624-628.   DOI: 10.11720/wtyht.2014.3.38
    Abstract   HTML   PDF (1773KB) ( 631 )

    In the construction sites of Shandong University and Central Stadium for Olympic Games in Jinan, the ground-penetrating radar was adopted to investigate the karst foundation and, as a result, the development situation of karst fissures was ascertained rapidly and effectively. Engineering practice shows that, in the engineering application, geological survey data should be analyzed thoroughly at the early stage to rationally determine the detection parameters, and the investigation should be combined with such methods as engineering drilling so as to continuously accumulate experience and obtain satisfactory engineering results.

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