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  • Table of Content
      03 April 2018, Volume 42 Issue 2 Previous Issue    Next Issue
    For Selected: View Abstracts Toggle Thumbnails
    CONTENTS
    The application of the airborne electromagnetic method to rapid prospecting breakthrough in high mountain areas
    XIANG Li-Na, WANG Zhi-Hong, SUN Dong-Hua, WU Xian-Hong, WEI Yong-Qiang
    Geophysical and Geochemical Exploration. 2018, 42 (2): 225-233.   DOI: 10.11720/wtyht.2018.2.01
    Abstract   PDF (1044KB) ( 586 )
    In order to find an effective means for quick prospecting breakthrough in high mountain areas, the Airborne Survey and Remote Sensing Center of Nuclear Industry carried out large-scale airborne electromagnetic demonstration survey in the Wulonggou gold deposit which is located in the Tibetan Plateau. With high-precision measurement and slow undualating flight suitable for the terrain situation, qualified raw data were acquired, and then detailed data processing, analysis of petrophysical parameters of rocks, and fast drilling verification were carried out, which made it possible to find a series of metal minerals, thus opening up a new prospect for airborne electromagnetic survey. The rapid prospecting breakthrough of 'three simultaneous' is realized. According to the demonstration survey and the prospecting effects, the large-scale electromagnetic method has the advantages of rapidness, high precision, low cost and significant effect in high mountain areas, thus having broad application and promotion prospect in such areas.
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    The application and significance of deep prospecting by using geogas survey in Xitian area, Hunan province
    LIU Ying-Han, YANG Ke, CHEN Hang-Xin, WANG Huan-Huan, LUO Jian-Lan, ZHU Hao-Feng
    Geophysical and Geochemical Exploration. 2018, 42 (2): 234-240.   DOI: 10.11720/wtyht.2018.2.02
    Abstract   PDF (808KB) ( 289 )
    Xitian area on Hunan province is located in the famous human Naning tungsten-tin polymetallic metallogenic belt and that shows huge prospecting exploration in recent years. Because of the Quatemary cover prospecting difficulty in crease, the coverage effective optimization methods is imminent with the deepening of the exploration work. Geogas survey prelimary solved the capture medium background influence, field operation system error and other issues by the unremitting research for many years, In combine with other methods, Xitian area on Hunan province optimization tungsten target applications found in the 190 meter deep underground tungsten ore body. The author thinks that the geogas survey can be used as a deep search for concealed deposies and effective geochemical exploration methods, in the coverage area of prospecting target areas selection play a huge role, promote the explorations of concealed deposites.
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    Surveying fault structures by geophysical exploration technique on the northwestern margin of Xining basin
    LONG Hui, SUN Sheng, LIU Yi, GUO Shu-Jun
    Geophysical and Geochemical Exploration. 2018, 42 (2): 241-246.   DOI: 10.11720/wtyht.2018.2.03
    Abstract   PDF (886KB) ( 301 )
    The temporal-spatial distribution characteristics of fault structures on the northwestern margin of Xining basin were investigated by using the audio-magnetotelluric method and 2D seismic exploration,with the purpose of providing the hydrogeological borehole properly so as to carry out the comprehensive investigation and evaluation of hydrogeology,environmental geology and engineering geology in eastern cities of Qinghai Province,find out the stratigraphic structures and geological structures,and study geophysical characteristic parameters in the key region.The results show clearly that there exists Xiamen thrusting-nappe fault on the northwestern margin of Xining basin,which dips NW,with dip angle about 65 °.The other two fractures were found in the river valley,away from mountains,and both are presumably associated with Nanmenxia strike-slip fault.In addition,the response characteristics of stratigraphic lithology,apparent resistivity and the velocity of seismic reflection wave were summarized.The hydrogeological borehole was drilled to verify the existence of Xiamen thrusting-nappe fault.The drilling coring is quite consistent with the results from the geophysical exploration methods.Several fault fracture zones exist in this borehole penetrating the Neo-Proterozoic crystalline limestone.
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    An integrated ore-prospecting method and model in search for Shuangshan alkali syenite Nb deposit in Fangcheng County, Henan Province
    CHENG Xing-Guo, CHEN Xin, YAN Hong-Pu, SONG Na-Na, NING Yong
    Geophysical and Geochemical Exploration. 2018, 42 (2): 247-252.   DOI: 10.11720/wtyht.2018.2.04
    Abstract   PDF (671KB) ( 427 )
    In this paper, an integrated ore-porspecting method is put forward in search for alkali syenite type "rare metal and REE" ore deposits. The method includes finding prospecting target through stream sediment survey, delineating the mineralized zone by rock survey, the performance of geological mapping of characteristic minerals to find the ore-bearing geological bodies, the control of the surface orebody by trench and the verification of the deep orebody by drilling. The combination of these techniques for ore-prospecting is economical, rapid and efficient in practice. Based on analysis and study of various prospecting techniques, the authors have built a prospecting model, which has guiding significance in search for alkali syenite type Nb-REE polymetallic deposits in China.
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    The application of EH-4 dual-power electromagnetic system to evaluating the shallow groundwater
    XIE Zhi-Feng, DU Fa, GAN Bin
    Geophysical and Geochemical Exploration. 2018, 42 (2): 253-258.   DOI: 10.11720/wtyht.2018.2.05
    Abstract   PDF (825KB) ( 316 )

    Talatan area in Gonghe basin of Qinghai Province is rich in Quaternary unconsolidated rock pore water, characterized by similar aquifer and aquiclude resistivity. Therefore, the common ground electric prospecting results look fuzzy, and it is difficult to precisely determine the groundwater level and the thickness of the aquifer. Using dense frequency and high vertical resolution characteristics of the EH-4 dual-power electromagnetic system, the authors made an effective trial above the known well. Based on a comparison with the borehole data, the authors calculated the empirical correction coefficient, then carried out MT "十" shape profile measuring and Bostick 1D inversion and EMAP 2D inversion to profile data in the work area, and checked empirical coefficient of the inversion results. Through synthesizing 1D and 2D inversion results, the authors formed inference geological section to quantitatively identify the buried depth and aquifer thickness of the groundwater, and successfully determined well spacing. The expected water inflow was obtained at the designed depth, and the interpretation accuracy of MT method was greatly improved.

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    Analysis on the characteristics of the uranium enrichment migration and the beneficial sites of uranium ore prospecting in Zhongchuan area
    WEI Yong-Qiang, JIANG Min-Zhong, SUN Dong-Hua, ZHANG Ren-Hong, WU Xian-Hong
    Geophysical and Geochemical Exploration. 2018, 42 (2): 259-269.   DOI: 10.11720/wtyht.2018.2.06
    Abstract   PDF (1360KB) ( 280 )
    In order to find out the relative enrichment of uranium in the Zhongchuan area and the advantageous sites of uranium mine prospecting under the action of geochemical, this paper mainly analysis the distribution of original uranium and activated uranium and the migration characteristics of uranium by using of airborne gamma spectrometric data, which has discussed the uranium content and endowment of the strata(terrane) by using the parameters such as the abnormal superposition and the enrichment coefficient, and comparatively studied the uranium content of different rocks in zhongchuan area by using the parameters including the Ur, the uranium-thorium ratio and the uranium-thorium lining ratio. Finally, it classifies the strata and terrane into uranium-rich source concentration body, uranium-rich concentration body, uranium-poor source concentration body and uranium-poor concentration body, and uranium-rich source concentration body is the most favorable for mineralization. By comparing the uranium content of different rocks in zhongchuan area, it is believed that the uranium content of the Zhongchuan rock is better. The Zhongchuan rock is a uranium rock, and the rest are thorium rock; it points out that the main enrichment areas of activated uranium include the structure broken zone, ex-contact zone and the edge of the basin. The superimposed compounding area of uranium increment and activated uranium is the most favorable for mineralization.
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    A study of the two-dimensional morphology of Dengfuxian semi-concealed compound granitic body in Hunan Province
    SONG Cai-Jian
    Geophysical and Geochemical Exploration. 2018, 42 (2): 270-275.   DOI: 10.11720/wtyht.2018.2.07
    Abstract   PDF (734KB) ( 297 )
    This paper describes in brief the geological background of Dengfuxian half-concealed compound granitic body.According to characteristics of density,gravity and magnetic anomaly and surface geology as well as regional geochemical composite anomaly,the author holds that Dengfuxian gravity low is the reflection of Dengfuxian rock mass and its concealed part.Based on the gravity gradient zone,residual anomaly and zero line of vertical second derivative anomaly around the rock mass,the author determined the position and boundary of the semi-concealed rock mass,and chose a representative gravity profile to conduct two-dimensional morphological inversion.On such a basis,the author puts forward some new opinions in the aspects of the morphology,attitude,buried depth of the top and bottom as well as its contact relationship with the wall rocks,the distribution of the Batuan rock mass and its contact relationship with Hanba rock mass.
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    Forward modeling for research of main source
    LYU Zhen-Yu, BIAN Li-En, YU Ya, WANG Jun
    Geophysical and Geochemical Exploration. 2018, 42 (2): 276-284.   DOI: 10.11720/wtyht.2018.2.08
    Abstract   PDF (1451KB) ( 341 )
    B well field in Bohai Bay basin is affected by bidirectional sources,and its main source direction is uncertain due to the lack of research.In this study,forward modeling was applied to the study of the main source.The models were designed to simulate these two kinds of main control sources,verify the direction of the main source and the distribution of the reservoir by comparing the modeling response with the actual seismic reflection characteristics.In order to further demonstrate the conclusion that the western part of B well field is mud rich,the authors established different models by giving different wave impedance differences between the near source and the end of the progradation,and carried out forward modeling.Based on comparing the sandbody characteristics, the actual seismic reflection characteristics and the forward modeling responses,the authors have reached the conclusion that the oil-bearing sandstones of the lower D2 Formation in B well is the distal end of progradation that comes from northwestern Shijiutuo Uplift,and Shijiutuo Uplift is the main source of the study area,which is the potential target for the high quality reservoir.
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    Key technology of seismic acquisition of gas hydrate in Mohe permafrost area
    GE Zhi-Guang, CHEN Yong-Sheng, ZHOU Xiao-Xian
    Geophysical and Geochemical Exploration. 2018, 42 (2): 285-291.   DOI: 10.11720/wtyht.2018.2.09
    Abstract   PDF (1562KB) ( 142 )
    The exploration research on gas hydrate resources in permafrost areas has aroused much attention due to its huge potential resource value.Although the seismic exploration technology of marine gas hydrates is almost mature,the seismic exploration technology of gas hydrate in terrestrial permafrost area is still in the research phase,and there are still many problems in data acquisition,processing and interpretation. In this paper,the authors carried out the research on the seismic acquisition technology of gas hydrate in terrestrial permafrost area in China,conducted a comprehensive analysis and established a geological model of the study area on the basis of geological and geophysical data obtained in Mohe permafrost area.To tackle the exploration difficulties of the thin permafrost layer and deep complex structures,the authors conducted forward modeling based on the wave equation.Meanwhile,through a comparative analysis of the collected data,the authors put forward the data acquisition method of alternate blasting of small interval and shallow shots, small shots and moderate shots,which will acquire shallow-,middle-level and deep high SNR data for reservoir prediction and structure detection.
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    The application of large and medium scale gravity measurement to the Gaoer Banner half-concealed Ag-Pb-Zn polymetallic deposit,Inner Mongoli
    SU Mei-Xia, SUN Hui-Ling, ZHAO Zhi-Jun, GUO Ling-Jun
    Geophysical and Geochemical Exploration. 2018, 42 (2): 292-302.   DOI: 10.11720/wtyht.2018.2.10
    Abstract   PDF (1577KB) ( 402 )
    Gravity survey has been carried out in the basalt overburden area of the Gaoer Banner half-concealed Ag-Pb-Zn polymetallic deposit, Inner Mongolia. In residual gravity anomaly map of 1∶50000, the Gaoer Banner ore deposit is located at the distortions of the negative gravity anomaly contour line in the contact zone of alternate positive and negative anomalies. Results of 1∶10000 gravity survey, IP and geochemical soil measurement show that orebodies correspond to nearly east-west banded apparent chargeability anomalies, and Ag-Pb-Zn polymetallic anomalies correspond to the variable area of high and low resistivity anomalies. The north of the orebody is characterized by negative residual gravity and low resistance, while the south of the orebody shows positive residual gravity and high resistance. Negative residual gravity in the north results from the concealed rock mass (Carboniferous granite) with low density, low resistance related to east-west tectonic fracture zone and the stockwork vein in it. Positive residual gravity is associated with Niqiuhe Formation. Sandstone with high density and high resistance results from fine-grained feldspar quartz sandstone and siltstone of Niqiuhe Formation. The fine-grained feldspar quartz sandstone and siltstone block and ore fluid migration probably resulted in deposit formation in the structural fracture zone on the northern side. Large scale gravity survey, electrical measurements and geochemical soil survey are not only important geophysical basis for the study of metallogenic environment, but also provide important information for orebody location.
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    A study on 1∶50 000 stream sediments survey in Beishi area,Guangdong Province
    LI Chong, HAO Zhi-Hong, ZHANG Zhong-Jin
    Geophysical and Geochemical Exploration. 2018, 42 (2): 303-311.   DOI: 10.11720/wtyht.2018.2.11
    Abstract   PDF (1505KB) ( 194 )
    A study on mesh experiment of stream sediments survey at a scale of 1∶50 000 was conducted in a selected area about 310 square kilometers of Guangdong Beishi area. The -10~+80 mesh and -60 mesh of stream sediments was collected at the same sampling site for the content analysis of various elements. The effect of mesh was evaluated comprehensively from the distribution characteristics of elements content, the enrichment tendency and the characteristic of geochemical. The result shows that:1) The weight of the -10~+80 mesh assumes absolute?superiority?in stream sediments. 2) Elements in the two grade with similar content distribution characteristics in the mass and enriched in high background or mineralization zone with varying degrees,in low background or non-mineralization zone by contrary, except W、Sn、Pb. 3) The regional geochemical distribution of most elements in -10~+80 mesh shows a higher degree of agreement with the regional geological and more close to the geological boundary. 4) Elements in -10~+80 mesh shows a larger scale and intensity geochemical high background and positive anomaly than -60 mesh, particularly in Mo, Sb. Therefore, the optimal sampling fraction of the Beishi area in Guang Dong is -10~+80 mesh.
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    Geochemical divisions of Yanchiwan area in western Qijian Mountain of Gansu Provinceand their characteristics
    LI Chun-Liang, ZHANG Wei
    Geophysical and Geochemical Exploration. 2018, 42 (2): 312-315.   DOI: 10.11720/wtyht.2018.2.12
    Abstract   PDF (516KB) ( 345 )
    The geochemical data of stream sediments contain significant geological and geochemical information. In this study, R factor analysis method was applied to 1∶250 000 stream sediments data from Western Qilian Mountain. Five geochemical zones were recognized and their geological implications were discussed according to element association. The geochemical zones correspond to the tectonic units, and therefore these results can provide abundant geochemical implications for basic geology research, prediction of prospective areas and further division of Grade IV ore-forming belts.
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    The application of ground-penetrating radar to ore exploration in the Jiajika rare metal orefield
    HUANG Tao, FU Xiao-Fang, YANG Rong, FAN Jun-Bo
    Geophysical and Geochemical Exploration. 2018, 42 (2): 316-324.   DOI: 10.11720/wtyht.2018.2.13
    Abstract   PDF (1197KB) ( 464 )
    A superlarge X03 rare metal vein has been recently discovered in the Jiajika orefield in western Sichuan. In the exploration, the ground-penetrating radar (GPR) was used to probe into shallow geological structures in the Jiajika orefield for the first time. By analyzing and comparative study of the model simulation, the measured GPR profile and the drilling data, it is found that the GPR image can effectively reveal the shallow geological structures beneath the Quaternary soil in this orefield. The characteristics of different reflections from the boundaries between acidic veins or boulders and their wall rocks, such as schist or Quaternary soil, were identified; by using the GPR method, the geological features at the top of the concealed X03 and other lithium veins were uncovered. Through this study, it is found that GPR detection is an effectively way to explore rare metal veins, which can replace the shallow trenching method and achieve green exploration as well as rapid prospecting and evaluation.
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    The application of GPR in detecting the depth of bedrock
    LIU Sheng-Rong, ZHANG Jin-Ai, TANG Xiao-Ping
    Geophysical and Geochemical Exploration. 2018, 42 (2): 325-330.   DOI: 10.11720/wtyht.2018.2.14
    Abstract   PDF (780KB) ( 453 )
    In order to cooperate with the East Tianshan-Beishanarea geochemical exploration work,we carry out the Quaternary thickness and bedrock surface depth detection in the Yuhai area. In order to find the bedrock surface in Yuhai area, the bedrock survey was carried out on the experimental area and the demonstration area to obtain the depth of bedrock depth, to provide depth reference data for drilling sampling, and the combined application of ground penetrating radar and single point electric sounding method in bedrock Survey. Yuhai area is located in the north of the Kanggoul fault, the results show that in the south area that the along north side of the Kangguer fracture, Neogene thinner,the depth of the bedrock can be effectively detected by the ground penetrating radar and the single-electron sounding method, There is a negative correlation between the bedrock depth and the topographic contour in the north and south direction, with a depth of 1~21 m; the bedrock fluctuation is larger in the east-west direction, showing a deeper depth in the west, more than 12 meters,the middle of the shallow, in the 4~20 m, the eastern part of the 8~30 m, white board to the central part of the region can be greater than 20 meters, but the range is small. The engineering practice shows that it is feasible to combine the ground penetrating radar and single-point electric sounding method in Yuhai bedrock survey to provide reliable basic data for later drilling.
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    A comparison of the inverse Q filtering methods based on wavefield continuation
    YU Dai, HE Zhi-Jun, SUN Yuan, WANG Ying
    Geophysical and Geochemical Exploration. 2018, 42 (2): 331-338.   DOI: 10.11720/wtyht.2018.2.15
    Abstract   PDF (963KB) ( 320 )
    Wavefield continuation algorithm is the most common inverse Q filtering method;nevertheless,due to the unstability of amplitude factor,part of the high frequency is magnified,which affects the results of inverse Q filtering.It is thus confirmed that complete stability amplitude compensation is only related to Glim by formula derivation,which causes difficulty to improve deep seismic wave resolution.The authors systematically analyzed the filter properties of different amplitude compensation operators in the wavefield continuation inverse Q filtering.Gain control compensation method is neither magnify nor suppress a certain frequency.Regularized and iterative compensation methods not only have strong anti-noise capability but also have better amplitude compensation capability for deep seismic waves.By applying different amplitude compensation operators to theoretical models and actual data of cross-well seismic data,the authors found that regularized and iterative amplitude compensation factors have strong suppression effects on high-frequency interference;for middle and deep part of seismic records and seismic records with low-Q energy attenuation,they also have better compensation effects.
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    Static correction and its application to seismic data of loess tableland area
    XIA Chang-Liang, WANG Yong-Ming, HU Hao, LI Hong-Xia, WANG Xiang-Chun
    Geophysical and Geochemical Exploration. 2018, 42 (2): 339-346.   DOI: 10.11720/wtyht.2018.2.16
    Abstract   PDF (1192KB) ( 192 )
    A new method of progressively united static correction is proposed for the serious static correction problem of seismic data of loess tableland area in southern Ordos basin.Firstly,grid tomographic inversion static method is used to solve the problem of long wavelength static;secondly,difference residual static method of first arrival is used to solve the problem of short wavelength static;finally,a new hybrid optimization method for estimating static corrections is put forward to solve residual static problem,which involves energy maximization,simulation annealing and hereditary algorithm.The practical application results of seismic data of loess tableland area show that the events of stack section of applying the above method is continuous with good consistency,and the diffraction wave characteristics of breakpoint are obvious.It is thus held that the progressively united static method can solve the static problem of seismic data obtained in this area.Good processing result can be obtained.
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    The static correction method of wave impedance layer and its application
    WANG Hai-Li, WANG Yong-Sheng, WANG Biao, MA Li-Xing, ZHANG Xian-Jian
    Geophysical and Geochemical Exploration. 2018, 42 (2): 347-351.   DOI: 10.11720/wtyht.2018.2.17
    Abstract   PDF (885KB) ( 204 )
    Yingxiongling area of Qaidam Basin has a strong wave impedance interface,which serves as the earthquake model inversion symbol layer to calculate low and high frequency static correction components.The method makes full use of the depth information,refraction information and reflection information of the interface of shallow strong wave impedance,and takes into account the low and high frequency.Large scale application of this method in Yingxiongling area improved SNR of seismic section and complex structure imaging precision,which indicates that the static correction is an effective method to solve extremely low SNR complex static correction of Yingxiongling area.
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    Box wave analysis of Nima area in Qiangtang basin
    WANG Fei, PEI Jin-Mei, LIU Feng-Zhi, LIU Zhi-Huan, LI Guo-Shun
    Geophysical and Geochemical Exploration. 2018, 42 (2): 352-357.   DOI: 10.11720/wtyht.2018.2.18
    Abstract   PDF (1429KB) ( 266 )
    The surface and geological conditions of Qiangtang basin is complicated,the data signal to noise ratio is extremely low,the folding of strata is serious,and hence the seismic data processing is very difficult. In order to grasp the characteristics of interfering waves in the region more effectively, the authors selected the appropriate seismic exploration parameters and put forward the appropriate box wave investigation method.Through the box wave analysis, it is found that the regular interference wave is well developed with obvious regularity,but the speed of energy and other aspects show evidentdifferences.Through the combinational indoor analysis, the authors detected that the accepting combination form has a rather great impact on the data, and such parameters as the number of received combinations, the base distance and graphics also affect the data quality.
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    A directional borehole radar 3D imaging algorithm based on arctangent method
    LIU Si-Xin, WANG Wen-Tian, LU Qi, LI Hong-Qing, FU Lei
    Geophysical and Geochemical Exploration. 2018, 42 (2): 358-362.   DOI: 10.11720/wtyht.2018.2.19
    Abstract   PDF (539KB) ( 464 )
    As a special mode of GPR, the directional borehole radar system can not only detect underground target depth and the radial distance but also identify the azimuth of target, and then it uses the azimuth for 3D imaging. The directional drilling radar in this paper consists of a transmitting antenna and four receiving antennas, and the four receiving antennas are distributed on the ring perpendicular to the borehole axis. Based on the insignificant difference between the four different receiving antenna signals, the authors propose the arctangent method for calculating azimuth angle. The combination of the azimuth angle and the signal produces the horizontal and vertical slice data, thus eventually realizing the borehole radar 3-D imaging algorithm. Finally, the effectiveness of the algorithm is verified by numerical simulation results.
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    The key technology of structural mapping with scarce seismic data and complex terrain condition and its application:A case study of D Basin
    LI Pei-Pei, LIU Zhi-Guo, YANG Song-Ling, WANG Xiao-Min, XU Shan-Hui
    Geophysical and Geochemical Exploration. 2018, 42 (2): 363-368.   DOI: 10.11720/wtyht.2018.2.20
    Abstract   PDF (818KB) ( 188 )
    The scarcity of data and the complicated geological conditions are often encountered in overseas exploration,so the difficulty and challenge of exploration are directly aggravated.Therefore,it is urgently needed to get the research results quickly and effectively so as to guide the exploration.As an example,D Basin is characterized by scarce data and complex terrain conditions.In this paper,a set of mapping techniques and processes are summarized,which are applicable to this area.Combined with seismic survey,drilling well and diversified information,the authors integrated the digital geological profile and the gravity and magnetic information with trend surface constraints into the grid structure.The effective trend constraint of seismic blank area was also carried out,thus obtaining effective basic regional geological maps and achieving good application effect.The results obtained by the authors have laid a solid foundation for the further basin structural analysis and structural unit division.
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    Experimental research on the detection of aromatic hydrocarbons for soil samples of oil and gas geochemical exploration by rapid solvent extraction and fluorescence detection
    LU Li, NING Li-Rong, SUN Chang-Qing, GAO Jun-Yang, WANG Guo-Jian, YANG Jun
    Geophysical and Geochemical Exploration. 2018, 42 (2): 369-373.   DOI: 10.11720/wtyht.2018.2.21
    Abstract   PDF (511KB) ( 170 )
    Through optimizing the detecting conditions of the aromatic hydrocarbon for soil samples, such as the blank experiment, sample weight, extraction temperature and extraction pressure, the authors obtained the best analysis conditions. According to the experimental results, the method has been established. Methodological indicators such as repeatability has been used to evaluate the method. Compared with the conventional extraction effect, the extraction rate of rapid solvent extraction has been increased. In a known geological section south of Nanyang sag, North Ma Zhuang area, the application effect of rapid solvent extraction with fluorescence method was carried out. The results show that this method can describe the regional geochemical anomalies.
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    The application of normalized total horizontal derivative vertical derivative method to the interpretation of in situ data
    ZHAO Qiang
    Geophysical and Geochemical Exploration. 2018, 42 (2): 374-380.   DOI: 10.11720/wtyht.2018.2.22
    Abstract   PDF (788KB) ( 359 )
    The normalized vertical derivative of the total horizontal derivative method is a potential field interpretation method based on combination of horizontal and vertical derivatives,highlighting linear structure by calculating the total horizontal derivative of the vertical features or rock geological boundary.With the metal ore resources in Xiangshan District of Zhongwei City in Ningxia and the distribution of nonmetallic mineral resources areas as the study objects,the utilization of this method can distinguish between rock mass and geological plane range clearly,and determine the location of the maximum value of the rock mass through the boundary position and level distribution.The results show that the method of normalizing the total horizontal derivative and vertical derivative can qualitatively explain the distribution range of rock mass and thus has fairly good application effect.
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    Geochemical characteristics of selenium-rich soil in Quanzhou county of Guangxi
    HUANG Zi-Long, LIN Qing-Mei, FANG Ru-Hai
    Geophysical and Geochemical Exploration. 2018, 42 (2): 381-385.   DOI: 10.11720/wtyht.2018.2.23
    Abstract   PDF (485KB) ( 435 )
    Based on evaluation of surface soils in Quanzhou county of Guangxi and studied characteristics of selenium overall distribution, controlled factors and ecological effect of soils were presented. The results show that there has a large area of selenium-rich soils. The average selenium content is 0.60×10-6. Selenium-sufficient and selenium-rich soil’s area occupies 17.38% and 81.88% of the total area. The distribution of selenium in soils is affected by soil parent material, soil type, pH value and so on, which mainly controlled by soil parent material and has obviously inherited. The soil environment quality of the study area is good and the selenium-enriched agricultural products are rich, which has good development prospect.
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    Geochemical characteristics of selenium-rich soil in Shouning County of Fujian Province
    WU Jun
    Geophysical and Geochemical Exploration. 2018, 42 (2): 386-391.   DOI: 10.11720/wtyht.2018.2.24
    Abstract   PDF (477KB) ( 473 )
    Based on the analysis of selenium content in soil and agricultural products in the study area, the authors studied the distribution characteristics and influencing factors of total selenium, and analyzed the characteristics of selenium content in agricultural products. The results show that the selenium contents were controlled by the geological background. It was much higher in the Third and Fourth members of Jurassic Nanyuan formation than in other geological background regions.In addition, the contents of selenium in soil under different soil types showed a great difference, and the land use types also has a certain impact on it. The correlation analysis indicates that the selenium content in soil has a significant correlation with pH, organic matter and metal oxides such as TFe2O3, indicating that the physicochemical properties of soil play important roles in the geochemical behaviors of selenium. The significant correlation between the selenium content and heavy metals indicates that there is a certain assorted relation between selenium and heavy metals in primary sulfide mineral.
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    Combined use of active and passive surface waves in the deep overburden area
    FENG Yun, SHA Chun
    Geophysical and Geochemical Exploration. 2018, 42 (2): 392-397.   DOI: 10.11720/wtyht.2018.2.25
    Abstract   PDF (758KB) ( 549 )
    The overburden thickness of the river bed is deep in southwestern China,and it is important to rapidly obtain the S-wave velocity of foundation site in hydropower engineering survey.Due to its low cost and simple operation,surface wave method has been widely used to detect shallow structure by S-wave velocity.In this study,the authors used active source and passive source surface wave methods to obtain S-wave velocity on the hydropower station dam in southwestern China.The active source surface wave method conducts detection with high resolution,and the passive source surface wave method gives a deeper investigation.They have their own advantages respectively.
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    The application of generalized S-transform of Rayleigh waves to detecting near-surface fissures
    SHAO Guang-Zhou, DONG Jin, DONG Zhao-Tang
    Geophysical and Geochemical Exploration. 2018, 42 (2): 398-404.   DOI: 10.11720/wtyht.2018.2.26
    Abstract   PDF (759KB) ( 259 )
    Ground fissures constitute a kind of geological disasters which not only cause direct damage to various buildings but also result in a series of environmental problems.It is therefore an important task to detect the ground fissures effectively in many engineering projects.In this paper,an experimental research on using Rayleigh waves to detect ground fissures was conducted.The generalized S-transform was adopted to extract the arrival time of the diffracted Rayleigh waves from the ground fissure at a certain receiver in time-frequency domain.And then the arrival times were used to calculate the locations of the ground fissures.In this paper,two half-space fissure models and a real world data analysis were used to demonstrate the feasibility and effectiveness of detecting ground fissures with the generalized S-transform.The theoretical models and the real world example show that it is feasible and effective to use the generalized S-transform to detect ground fissures.
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    Numerical simulation of parallel pipeline in mining areas based on magnetic anomaly
    FENG Mu-Qun, LIU De-Jun, PAN Qi, FENG Shuo, LIU Jia-Ning
    Geophysical and Geochemical Exploration. 2018, 42 (2): 405-411.   DOI: 10.11720/wtyht.2018.2.27
    Abstract   PDF (613KB) ( 243 )
    In order to detect underground parallel pipeline accurately and efficiently,the authors used the magnetic dipole method to simulate underground parallel iron pipeline model,chose MATLAB to calculate the magnetic anomaly curve generated by the model,and analyzed changes of the magnetic anomaly curve caused mainly by the basic shape and the number of peaks.Numerical simulation results show that the amplitude and magnetic width of magnetic anomaly signal are both affected by the selected parameters.Specifically,the center distance,depth and susceptibility all significantly change the basic curve shape as well as the number of curve peaks;the length,diameter and thickness affect the amplitude,but do not change the basic shape;with the same parameters,the calculated magnetic anomaly curves respectively from the COMSOL software and the magnetic dipole method have the same normalization shape,which shows that the demagnetization affects the curve amplitude of magnetic anomaly, thus proving the validity of magnetic dipole method in the parallel pipeline model forward analysis.
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    BEAM tunnel advanced geological prediction method based on optical fiber current sensing
    GAO Xin-xing, ZHAO Bin, LU Li-yong, YU Jie, XU Ya
    Geophysical and Geochemical Exploration. 2018, 42 (2): 412-421.   DOI: 10.11720/wtyht.2018.2.28
    Abstract   PDF (970KB) ( 259 )
    Low contact resistance between the cutterhead and the shield leads to the loss of insulation between the detecting current and the guarding current in BEAM-INTEGRAL method and generates the leak current. Experiments indicate that the leak current reduces the calculation accuracy of apparent resistivity and causes the omission of geological disasters in advanced prediction. In order to eliminate negative effects of the leakage current, we propose an advanced geological prediction method based on optical fiber current sensing. This method can measure the leakage current by a fiber current sensor, which is attached on the main bearing of the TBM. The experiment reveals that this method can eliminate the negative influence of the leakage current on the apparent resistance measurement and improve geological advanced prediction’s detecting precision compared with BEAM-INTEGRAL method.
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    Research on geoelectric characteristics of Holocene ancient channels in Xuzhou area
    JIANG Guo-Qing, HUANG Jing-Jun, ZHANG Da-Lian, XU Shi-Yin, LU Jin-Tian
    Geophysical and Geochemical Exploration. 2018, 42 (2): 422-428.   DOI: 10.11720/wtyht.2018.2.29
    Abstract   PDF (897KB) ( 295 )
    Investigation of ancient channels is of great significance for earthquake disaster reduction, urban planning and reasonable development of ground water resources. Based on the significant electrical property difference of rock and soil in Xuzhou area, Holocene ancient channel was detected using high density resistivity method. Firstly, through numerical simulation of geoelectrical models and field test nearby boreholes, the effectiveness of high density resistivity method in detecting Holocene ancient channel and the device choice were discussed; Secondly, the result maps of section, plane and 3D were analyzed; Finally, the detecting result of high density resistivity method was verified by boreholes. Result of theoretical research and applied case indicates that Holocene ancient channels in Xuzhou area show representative electrical field response characteristics, information such as morphology and stratum structure of ancient channels can be obtained through the analysis of response characteristic; the dipole-dipole device of high density resistivity method is very sensitive to the structure variation of overburden, maximum anomalous intension, and it has certain advantages in the aspect of stratum division, so dipole-dipole device is the preferred device for the investigation of ancient channels; through arranging multiple survey lines in investigated area and with the help of 3D visual software platform, 3D spatial interpretation of target can be realized, and interpreted results will intuitively reveal the 3D morphology and spatial distribution characteristics of Holocene ancient channels.
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