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  • Table of Content
      15 April 2011, Volume 35 Issue 2 Previous Issue    Next Issue
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    GRAVITY DEDUCTION AND INTERPRETATION OF GEOLOGICAL STRUCTURE IN HEBEI PROVINCE
    ZHANG Ya-dong, DONG Jie, XIAO Jin-ping
    Geophysical and Geochemical Exploration. 2011, 35 (2): 143-148.  
    Abstract   HTML   PDF (886KB) ( 1064 )

    Based on a deepgoing study of the gravity field characteristics of Hebei Province in combination with geological and other geophysical data, the authors made a deduction and interpretation of the geological structure, divided the geological structures in the whole province into major tectonic units and fault structures, delineated rock bodies, basins and sags. The results provide important information for ore resources potential evaluation and ore prognosis.

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    A TENTATIVE DISCUSSION ON THE TAIL EFFECT OF NORTHEAST ALTUN FAUL TBELT IN THE LIGHT OF GEOPHYSICAL FIELD INFORMATION
    QIU Ai-mei, LI Bai-xiang
    Geophysical and Geochemical Exploration. 2011, 35 (2): 149-154.  
    Abstract   HTML   PDF (1552KB) ( 945 )

    According to the regional geophysical data, the Altun-Qilian arc giant gravity gradient zone is located at the northeastern edge of the Qinghai-Tibet block and forms the boundaries between Qinghai-Tibet block, Tarim basin and North China block. With the NEE-trending gravity gradient zone, this zone reflects the Altun fault characterized by both sinistral strike-slip and thrust. West Qilian is characterized by alternate NWW-trending arc gravity high and gravity low, which reflects the framework of squeeze nappe, thrust superposition and basin-range coupling within the Qilian orogenic belt. Between Dunhuang and Jinta, due to the tail effect of northeast Altun fault, a series of NNE-trending pull-apart fault basins associated with NEE-trending strike-slip fault and filling of mainland alkaline basalt in the pull-apart space were produced, which caused corresponding magnetic anomalies characterized by gravity low. Due to energy reduction and conversion, the Altun fault terminated in Huahai fault of Jinta basin, thus not extending eastward.

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    CHARACTERISTICS AND ORE-CONTROLLING REGULARITY OF CONCEALED FAULTS IN THE DAMAIDI ORE DISTRICT, SOUTHWESTERN YUNNAN PROVINCE
    ZHANG Xiao-yong, PENG Run-min, ZHANG Lin, YI Ai-wen, ZHAO Tian-ping, LIU Ai-min
    Geophysical and Geochemical Exploration. 2011, 35 (2): 155-159.  
    Abstract   HTML   PDF (840KB) ( 615 )

    The study of faults is very important in that nonferrous metal deposits are almost always related to faults. At present, the study of faults is confined to observing and analyzing the earth's surface, with very insufficient attention paid to the subsurface study. The authors hold that the EH4 section is a good section for studying faults in the Damaidi ore district. The inversion results of EH4 can show the variation of the faults in the subsurface, especially the width, depth, strata and lithology of the faults. Based on these characteristics, we can make an estimation of the faults, which helps explore concealed ore deposits.

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    THE PROGRESS OF SEISMIC TOMOGRAPHY RESEARCH IN THE TIBETAN PLATEAU
    ZHENG Hong-wei, LI Ting-Dong, GAO Rui
    Geophysical and Geochemical Exploration. 2011, 35 (2): 160-164.  
    Abstract   HTML   PDF (589KB) ( 932 )

    A large amount of broadband exploration works have been conducted in Tibetan Plateau to study the crust and upper mantle structure.The present author collects all the temporary and permanent digital seismic stations in Tibet and its surrounding areas.This paper gives a general review on the research results of tomography in Tibetan Plateau deep structure,such as the low-velocity zone in the crust,subducting of Indian plate lithosphere,tectonic of the northeastern and northwestern Tibet.

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    ORE-PROSPECTING METHODS AND POTENTIAL ANALYSIS OF THE XINZHAI TIN-POLYMETALLIC DEPOSIT
    JIAO Yan-Jie, WU Shou Ai-li, WU Wen-xian, LI Hua, DENG Ke
    Geophysical and Geochemical Exploration. 2011, 35 (2): 165-169.  
    Abstract   HTML   PDF (865KB) ( 728 )

    The Xinzhai ore deposit discovered in recent years is a large-size tin deposit. On the basis of early period regional geological and geochemical survey, an arrangement of integrated geophysical methods was made. In accordance with the idea of outskirt ore-prospecting and ore-search based on known ore spots, the dual-frequency electromagnetic sounding IP method was employed in the work area. Electromagnetic sounding underground rock reflected the fabric patterns and related electrical anomalies, while IP measurements reflected the limits and unusual polarization characteristic frequency of a good ore body. In combination with various kinds of information and professional knowledge, the analytical capacity of geological ore-prospecting can be improved and the risk can be reduced. It is shown that at the depth of the Xinzhai work area there exist good prospects for mineralization.

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    PRIMARY HALO CHARACTERISTICS AND CONCEALED ORE BODY PROGNOSIS IN THE NANNONG LEAD-ZINC POLYMETALLIC DEPOSIT, SOUTHWESTERN ZHEJIANG PROVINCE
    WANG Qi, JIANG Yong-jian, YU Hai-tao, LIU Guo-chun, LIU Yong-li
    Geophysical and Geochemical Exploration. 2011, 35 (2): 170-175.  
    Abstract   HTML   PDF (1986KB) ( 1093 )

    The Nannong lead-zinc polymetallic deposit, located in an uplift area between Jiangshan- Shaoxing and Zhenghe-Dapu deep faults in southwestern Zhejiang Province, is one of the typical hydrothermal lead-zinc polymetallic deposits in this area. According to systematical sample collection as well as statistical analysis and calculation of data from drill holes, the authors determined combinational characteristics and axial zonation characteristics of elements as well as variation of geochemical parameters. On such a basis, the possible position of the concealed ore body was predicted. The results provide reliable geochemical evidence in search for deep concealed ore bodies in this area.

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    THE EFFECT OF GEOCHEMICAL EXPLORATION AND THE DISCOVERY OF GOLD AND MOLYBDENUM POLYMETALLIC ORE DEPOSITS IN SONGSHAN DISTRICT OF CHIFENG CITY, INNER MONGOLIA
    WANG Qiu-yin, CHENG Hua-sheng
    Geophysical and Geochemical Exploration. 2011, 35 (2): 176-182.  
    Abstract   HTML   PDF (981KB) ( 681 )

    The Mengguyingzi ore district lies in the Chifeng-Chaoyang gold ore belt and Xilamumulunhe metallogenic belt. Through 1∶25000 reconnaissance and 1∶10000 detailed investigation, geophysical and geochemical anomalies of the ore deposit were discovered. Drilling verification shows that this ore deposit is a metallic sulfide deposit with abundant gold and molybdenum. This ore deposit deserves further ore prospecting work in that its size is fairly remarkable.

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    PETROPHYSICAL CHARACTERISTICS OF PALAEOZOIC CLASOLITE IN THE TAHE OILFIELD
    FENG Xing-qiang, ZHONG Zhong-min
    Geophysical and Geochemical Exploration. 2011, 35 (2): 183-187.  
    Abstract   HTML   PDF (985KB) ( 574 )

    Based on the petrophysics theory, the authors measured the samples from the Silurian-Devonian Tertiary formation in the Tahe oilfield for ultrasonic compressional and shear wave velocities in rocks under the conditions of various temperatures, pressures and densities. The results show that the compressional and shear wave velocities show linear relationship in mudstone and sandstone fully saturated with water and oil. The rock velocities increase with the increasing temperature and pressure, whereas the rock velocities decrease with the increasing porosity in dry core samples and sampls saturated with water. According to Shuey's approximation, AVO forward modeling was conducted on the basis of petrophysical parameters. It is indicated that the AVO abnormal responses from Silurian-Devonian reservoir property belong to Class One in the Tahe orefield.

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    THE APPLICATION OF HIGH-PRECISION AEROMAGNETIC SURVEY IN WEST TIANSHAN AREA OF XINJIANG
    ZHENG Guang-ru, ZHANG Xiun-jie, FAN Zi-liang, ZHOU Jian-xin, SONG Yan-bing, WEN Shi-xin
    Geophysical and Geochemical Exploration. 2011, 35 (2): 188-191.  
    Abstract   HTML   PDF (912KB) ( 863 )

    This paper describes the effects of applying high-precision aeromagnetic survey in West Tianshan area. The high-precision aeromagnetic map contains very abundant magnetic anomaly information. The known iron deposits are clearly demonstrated in the map and, in addition, more than 50 iron anomalies are reflected in the map. The inspection of five anomalies led to the discovery of four ore-related anomalies, which are No.14,No.20,No.169 and No.374 anomalies. The discovery of these four ore-related anomalies has not only brought remarkable economic benefit but also provided typical examples for further application of high-precision aeromagnetic survey to the ore-prospecting work. Based on the results obtained, the authors hold that the high-precision aeromagnetic survey can be effectively used in the West Tianshan area and even in the whole low-exploration areas of western China for the purpose of prospecting for ferromagnetic ore resources.

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    CHARACTERISTICS OF GEOPHYSICAL AND GEOCHEMICAL ANOMALIES IN THE DONGPO LEAD-ZINC DEPOSIT OF HUNAN PROVINCE AND THEIR ROLE IN ORE-PROSPECTING WORK
    GUO Hai, ZHANG Guo-hua, LEI Zhi-yuan, Tan Yong-yan, ZHOU Jin-hua
    Geophysical and Geochemical Exploration. 2011, 35 (2): 192-197.  
    Abstract   HTML   PDF (1099KB) ( 1051 )

    Despite the existence of abundant ore resources in Dongpo, the proved lead-zinc reserves have begun to be exhausted after years of exploitation. As an assistant means in geological investigation, the method of high ground resolution magnetic measurement was put into practice mainly in potential surveying areas, followed by IP sounding method. High resolution magnetic scanning led to the discovery of 22 magnetic ΔT anomalies mainly along the contact zone of the Qianli Mountain. An analysis of geological conditions and geophysical-geochemical data revealed three remarkable anomaly zones, namely Yeijiwei-Niujiaolong, Meizilong and Shexingping-Tangzhashui. Drilling work in Meizilong area with strong M2 magnetic anomaly disclosed that the thickness of the mineralization is 10.86~32 m, suggesting a large-size skarn deposit with abundant Wu, Sn polymetallic resources. In Niujiaolong area with strong M9 anomaly, the thickness of the lead and zinc mineralized shatter zone reaches 6.4 m. Consequently, a geophysical-geochemical prospecting model in this region was built up, characterized by "two-lows and three-highs". The two-lows are the low apparent resistivity and gravity; whereas the three-highs refer to high ΔT , high apparent polarization and high amount of chemical substances (Pb, Zn, Ag, As,etc) in the earth. As there exists close relation between the Dongpo lead-zinc ore deposit and its surrounding structures, the selection of the survey areas must be based on rocks or underlying structures with strong responses to low gravity and low apparent resistivity. These areas are usually structural shatter zones or skarn zones.

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    THE PETROLEUM GEOLOGICAL SIGNIFICANCE OF SOLUBLE CATIONS IN NEAR-SURFACE SOIL
    LI Guang-zhi, CHEN Yin-jie, YIN Hong-jun, XUAN Hai-bo
    Geophysical and Geochemical Exploration. 2011, 35 (2): 198-202.  
    Abstract   HTML   PDF (621KB) ( 792 )

    During the formation of oil-gas and migration process, some soluble trace elements in the sedimentary organic matter will be separated and dissolved in the associated water. Some soluble trace elements in oilfield water and crude oil will dissolve in water and migrate with water to the near-surface place. Through analyzing variation of soluble anions in near-surface soil, we can track the oil-gas information underlying strata. A study of variation of near-surface soluble anions in the Xinchang gas field, Changde gas field and Pingfangwang oil field show that soluble anions in oilfield water mainly migrate in the form of water carriers, the upward migration passage of oilfield water determines the anomaly shape and pattern at the top of oil and gas reservoirs, and soluble anions have a certain indicating significance for oil and gas reservoirs in the underlying strata.

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    THE MECHANISM AND APPLICATION EFFECT OF THE GEO-ELECTROCHEMICAL METHOD IN SEARCH FOR CONCEALED GOLD DEPOSITS
    QIU Wei, PAN Tong, LI Yong-hu
    Geophysical and Geochemical Exploration. 2011, 35 (2): 203-205.  
    Abstract   HTML   PDF (1115KB) ( 760 )

    Geo-electrochemical extraction measurement method is a new quick,convenient and effective means in search for concealed ore deposits.A study of its mechanism and application effect proves that the application of the geo-electrochemical exploration method to prospecting for concealed gold deposit is feasible and practical.

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    THE GRADIENT SOUNDING PROFILE METHOD AND ITS APPLICATION
    Ge Wei-zhong, LU Yu-zeng, Ding Yun-he
    Geophysical and Geochemical Exploration. 2011, 35 (2): 206-211.  
    Abstract   HTML   PDF (1051KB) ( 1579 )

    According to the practical application of DC sounding, this paper puts forward a new gradient sounding profiles method. The surveying system can simplify the working procedure through using more than one receiver or multi-channel electrical measuring instrument in a number of electrical sounding points at the same time. Moreover, the gradient sounding system includes tri-electrode gradient arrangement, dipole-dipole gradient array and central gradient array, which is suitable to 2-D inverse interpretation. The system has been applied to metallic ore exploration and engineering investigation successfully.

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    EXPERIMENTS ON TECHNICAL CONDITIONS OF THE THERMOMAGNETIC TECHNOLOGY AND SOME RELATED PROBLEMS
    HU Shu-qi, MA Sheng-ming, LIU Chong-min, LI Bing, XI Ming-jie
    Geophysical and Geochemical Exploration. 2011, 35 (2): 212-217.  
    Abstract   HTML   PDF (694KB) ( 643 )

    Experiments on technical conditions of thermomagnetic methods include such contents as roasting granularity, temperature, time and thermomagnetic component separation. Based on conducting technical design and experiments on various technical aspects, the authors established a set of reasonable technical processes for sample roasting and thermomagnetic component separation. Some problems encountered in the experiments were also analyzed, which provides the basic technical support for the introduction and promotion of thermomagnetic geochemical methods.

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    POLE-DIPOLE/DIPOLE-POLE ARRAY SOUNDING TWO-DIMENSIONAL GEOELECTRICAL SECTION IMAGING FOR TIME DOMAIN INEDUCED POLARIZATION METHOD
    LUO Zhi-feng, WU Xiao-ping
    Geophysical and Geochemical Exploration. 2011, 35 (2): 218-222.  
    Abstract   HTML   PDF (1155KB) ( 1455 )

    :The double current supply, inline and combined pole-dipole/dipole-pole array for time domain induced polarization method is an unsymmetrical arrangement sounding technology composed of forward pole-dipole and reverse dipole-pole array. This paper shows the sounding principle with graphical representation. For collecting resistivity and chargeability raw data distribution features in the pseudosection with forward pole-dipole and reverse dipole-pole array, it is similar to MT in that MT raw data obtain "static state effect", and resistivity and chargeability raw data also obtain "partial topography " and "electromagnetism noise" effect and assumes "false belt anomaly" features. Forward pole-dipole and reverse dipole-pole array obtains resistivity and chargeability data and can respectively process two-dimension inversion, but only the combined pole-dipole/dipole-pole array can get the best geological effect, indicating that the strongpoint of the electrodes configuration array is that it can obtain massive collection data, strong induced polarization signal, larger penetration depth and highly surveying accuracy. With the electrical property parameters for resistivity and chargeability two-dimension inversion imaging techniques in the geoelectrical section, we can accurately determine the spatial distribution of the electric anomaly body and can also provide accurate geophysical basis for drilling verification of the electric anomaly.

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    THE APPLICATION OF THE DUAL-FREQUENCY IP METHOD TO THE DELINEATION OF THE COAL FIELD FIRE ZONE
    YU Chuan-tao, LIU Hong-fu, ZHANG Xin-jun
    Geophysical and Geochemical Exploration. 2011, 35 (2): 223-225.  
    Abstract   HTML   PDF (504KB) ( 755 )

    A tentative study was conducted in the coal mine fire zone by using the dual-frequency IP method with the assistance of radon measurement. The results of the two methods were well consistent with each other, which was substantiated by exploratory boring. It is shown that at the top of the coal mine fire zone there exists a very obvious abnormal reaction when the dual-frequency IP method is used. The apparent amplitude-frequency rate of the normal value is 2 times that of the background value zone, showing a high apparent amplitude-frequency rate characteristic. The apparent resistivity value is lower than that of the normal area, i.e., only 50%~75% of the value of the normal area. At the same time, the radon value in the fire area is higher than that of other areas. The use of dual-frequency IP method to detect the fire area should be promoted in that it provides a solution to the coal mine fire zones at different depths. This method can also be employed in dynamic monitoring of the coal field fire zone.

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    THE DEDUCTION OF THE STRIKE OF THE GEOLOGICAL CONCEALED FAULT BASED ON UNDERGROUND RADON MEASUREMENT
    LIU Chun-lai, TUO Xian-guo, HUANG Lian-mei, YAN Yong-ping, SONG Qian-qian, WANG Lei, LIU Jing
    Geophysical and Geochemical Exploration. 2011, 35 (2): 226-229.  
    Abstract   HTML   PDF (1021KB) ( 832 )

    In this paper, underground radon gas measurement was used in the work to find concealed unusual polarization characteristic faults. The authors employed shallow seismic exploration technology and high-density electrical method to give comparative validation in combination with geological in-situ verification. Analysis shows that the abnormal values obtained from radon measurement can well indicate locations of faults. With the underground radon measurement method, the authors detected the alignment of two other faults in the earthquake area, and made an evaluation of their relative activities. This method overcomes the time-consuming and high cost problem existent in other geophysical methods. In practical work, underground radon measurement provides the reference information for conducting other geophysical methods and implementing projects.

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    THE SCHEME FOR DESIGNING THE LASER INTERFEROMETER GRAVITY GRADIOMETER
    WU Qiong, TENG Yun-tian, GUO You-guang
    Geophysical and Geochemical Exploration. 2011, 35 (2): 230-233.  
    Abstract   HTML   PDF (896KB) ( 553 )

    Two kinds of gravity gradiometer are described in this paper: one is laser interferometer and the other is atom interferometer. The authors have found that free fall gradiometery offers much promise for dynamic measurements and the free fall system can either use macroscopic objects in free-fall (mirrors) or atomic fountains. The two systems have similar intrinsic sensitivities. Based on the initial gravity gradient measuring experiment with NIM-Ⅱ, the authors put forward two ideas to design the gravity gradiometer: Single-Interferometer and Dual-Interferometer. The authors favor the second one in that it can satisfy the precision requirement at the same size as the traditional absolute gradiometer.

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    COAL EROSION ZONE INTERPRETATION BASED ON SEISMIC ATTRIBUTES
    CUI Da-wei, WANG Yi, TIAN Qing-lu, LIU Zui-liang, QI Zhen-hong
    Geophysical and Geochemical Exploration. 2011, 35 (2): 234-237.  
    Abstract   HTML   PDF (694KB) ( 822 )

    Both seismic attribute technique and seismic facies analysis were used in the interpretation of coal erosion zones. Firstly, attributes were extracted from the reflection of the coal seam. Secondly, these attributes and the response characteristics of erosion zones were comparatively studied. Finally, the erosion zones were explained synthetically with attributes of sensitive response, and the erosion was determined. A comparison with the traditional method of drilling shows that the seismic attribute method can locate the coal erosion boundary accurately.

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    THE EFFECTS OF THE NUMBER OF GEOPHONES IN ARRAY ON NOISE ATTENUATION
    WEI Ji-dong
    Geophysical and Geochemical Exploration. 2011, 35 (2): 238-242.  
    Abstract   HTML   PDF (910KB) ( 812 )

    The geophone array in field data acquisition can suppress both the regular interference noise and the scattering interference noise. The regular interference noise is mainly suppressed by directional effect,while the scattering interference noise is mainly suppressed by statistical effect. Relevant theories hold that, when other factors remain fixed, the more geophones are used, the better results are obtained. It seems therefore that more geophones should be used to improve the seismic data quality; nevertheless, the authors' studies have proved that, if the number of geophones in a liner array whose sensitivities are suitably weighted is more than " +3"(where =effective-array-length /minimum-wavelength of regular interference noise), no obvious advantage can be seen by using more geophones. On such a basis, by calculating rose diagrams, the suitable number of geophones in an area-geophone-array or smearing can be pointed out, which is more economical. On the other hand, for the purpose of attenuating environmental noise, the more geophones are used in an array, the better result can be obtained under the condition that the effective array length is fixed. However, when the number of geophones reaches a certain level, no obvious improvement can be made. In addition,the authors' study also shows that the number of geophones has no definite relationship with the couple resonance noise. If the number of geophones in array is to be fixed, the geophone pattern should be taken into account. If the geophone pattern is unsuitable, adding geophones will not be beneficial to the noise attenuation. If the geophone sensitivity is not reasonably distributed, it cannot be helpful to the noise attenuation.

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    A 3D CONTINUOUS VELOCITY ANALYSIS OF TEM FICTITIOUS WAVE-FIELD AND ITS APPLICATION TO TUNNEL ADVANCED PREDICTION
    FAN Tao
    Geophysical and Geochemical Exploration. 2011, 35 (2): 243-247.  
    Abstract   HTML   PDF (503KB) ( 774 )

    In view of the fact that tunnel advanced geological prediction cannot effectively predict the flood in front of the tunnel face, this paper proposes a new method, i.e., transient electromagnetic wave-field transform continuation and imaging, which is based on the theory of floating plate and has proved to be very effective in predicting the unfavorable geological body in front of the tunnel face. With this desirable 3-D virtual velocity continuous analysis method, the problems of velocity extraction of observed data in migration imaging can be well solved. This paper puts forward the suitable working method of transient electromagnetism for the application in tunnel. In addition, the theoretical models and application examples were analyzed and calculated, and the results obtained coincide with the actual situation, showing that this velocity analysis method is feasible and effective.

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    THE DISCOVERY OF LAKE FACIES SELENIUM-RICH SOIL AND ITS ECOLOGICAL SIGNIFICANCE
    CAI Zi-hua, SONG Ming-yi, HU Yan-hua, HUANG Chun-lei, WANG Jia-en
    Geophysical and Geochemical Exploration. 2011, 35 (2): 248-253.  
    Abstract   HTML   PDF (873KB) ( 779 )

    Based on geochemical study of soil, the authors discovered a new type of selenium-rich soil in northern plain of Zhejiang, which occurs discontinuously around the Taihu Lake. The content of selenium in soil is from 0.084×10-6 to 1.296×10-6 , with the average value being 0.399×10-6, the standard deviation being 0.094, and the variation coefficient being 0.037. Studies show that the soil organic matter is closely related to selenium, but not related to soil pH. Under the conditions of rich organic matter and oxidation, content of selenium in such agricultural products as rice, corn, leafy vegetables, and beans is high. Further studies show that the source of selenium-rich soil is related to lake facies. On such a basis, a new type of selenium-rich soil is put forward.

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    THE DESIGN AND IMPLEMENTATION OF THE EVALUATION SYSTEM FOR ECOLOGICAL AGRO-GEOCHEMISTRY
    NIE Lan-shi, WANG Xue-qiu, YANG Zhong-fang, CHEN Yue-long
    Geophysical and Geochemical Exploration. 2011, 35 (2): 254-257.  
    Abstract   HTML   PDF (544KB) ( 654 )

    With the overall expansion of ecological geochemical investigation and evaluation, a large number of data have been accumulated; nevertheless, there is not yet an appraisal system widely used or approved at present. This paper adopts MapGIS6.7 platform to develop the ecological-geochemical appraisal system according to demands of agricultural ecological geochemistry. The software and hardware are described in detail, which include input of figures and maps, weighting, calculation of appraisal attribute values, mapping appraisal figures, analyses of space attributes etc. Generally, this system includes such parts as the database (surveyed data, figure data), the appraisal system, and the counting and inquiry system.

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    THE APPLICATION OF FREQUENCY ELECTROMAGNETIC SURVEY TO THE INVESTIGATION OF GEOELECTRICAL FEATURES AT A MINING ABANDONED SITE
    ZHANG Shao-hong, BIAN Xiang-shan
    Geophysical and Geochemical Exploration. 2011, 35 (2): 258-260.  
    Abstract   HTML   PDF (520KB) ( 543 )

    The frequency electromagnetic method was employed to investigate the geoelectrical features and map the extent of contamination at a mining abandoned site with the purpose of detecting the spread of groundwater and soil contamination, locating possible pathways of pollution and detecting the buried underground tanks. Based on an electrical conductivity analysis of the survey area, the authors delineated the geophysical anomaly zones. The results show that the frequency electromagnetic method technique is sensitive to conductive layers, has the capability of measuring small changes in subsurface properties in relation to underground water and is thus quite suitable for high-accuracy environmental monitoring.

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    THE KEY TECHNOLOGY FOR DIGITAL MAPPING OF MEASURED GEOLOGICAL PROFILE BASED ON AutoCAD
    YANG Li-rong, LAI De-jun, LUO Juan
    Geophysical and Geochemical Exploration. 2011, 35 (2): 261-264.  
    Abstract   HTML   PDF (465KB) ( 922 )

    The measured geological profile map and traverse map constitute an important part of the regional geological map and are used to reflect the underground structures and profile features. In addition, they are the basic maps in geological work. As the maps were drawn by hand in the past, they were not only inefficient but also not easy to preserve and update. The authors used the secondary development interface offered by the sophisticated graphics tools for AutoCAD as the map output stage, the format of EXCEL as the import data and the export of the result, and the Microsoft Visual Studio NET as the development of language to develop a Measured Geological Profile Mapping System which can automatically draw the measured Geological Profile Map and the Traverse Map. With the mapping of the geological survey section in Tibet as an example, this paper has verified the accuracy of the map and the precision of the system. It is shown that the map can meet the requirements for drawing Geological Profile Map and Traverse Map at a variety of scales.

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    SOME ADVANCES OF GENNERAL S TRANSFORM IN SEISMIC EXPLORATION
    MA Jian-qing, LI Qing-chun, WANG Mei-ding
    Geophysical and Geochemical Exploration. 2011, 35 (2): 265-269.  
    Abstract   HTML   PDF (1072KB) ( 848 )

    The generalized S transform is a relatively new time-frequency analysis method for non-stationary signal, which has the following characteristics and advantages: S transform inverse transform and Fourier transform is directly linked to ensure that it is the non-destructive transform; linear transform ensure there is no cross-terms; time-frequency resolution and the signal frequency-related; basic wavelet do not have to meet the permit conditions; scale makes the generalized S transform have good aggregation ability for frequency. Based on these characteristics and advantages, the generalized S transform has been widely used in seismic exploration. Such as dispersion analysis of Rayleigh surface wave, wave field separation and noising, Extraction of sedimentary cycles and the first-arrive detection of seismic wave, etc. In this paper, we summarize the present representative of the generalized S transform type, and combine with examples, expound the research progress of this method in seismic exploration. Finally, we give a prospect of generalized S transform in seismic exploration.

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    AN ANALYSIS OF CONVERTED-WAVE VELOCITY IN ANISOTROPIC MEDIA
    LI Qin, LI Qing-chun
    Geophysical and Geochemical Exploration. 2011, 35 (2): 270-273.  
    Abstract   HTML   PDF (774KB) ( 805 )

    The converted-wave time curve is non-hyperbolic and becomes more complex in anisotropic media. This paper has mainly discussed the method for anisotropic velocity analysis of PSV wave and conducted a velocity analysis of converted-wave in one-parameter method based on previous research results. As the velocity analysis of PSV wave is not independent from PP wave data, the authors made use of efficient information on PP wave data, simplified the procedure of velocity analysis and obtained the information of velocity and anisotropic parameters. To some extent, the authors' study improves the accuracy and efficiency and proves to be effective, as shown by the results of the model test.

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    THE APPLICATION OF TEM AND RESISTIVITY SOUNDING TO THE INVESTIGATION OF GOB AREAS NEAR SHAWU RAILWAY
    LI Yao-hua, YANG Jin, LI Shi-feng
    Geophysical and Geochemical Exploration. 2011, 35 (2): 274-279.  
    Abstract   HTML   PDF (694KB) ( 959 )

    The exploitation of iron ore near Shawu Railway (at 40 km+870 m) has led to the overlying rock distortion and collapse above gob areas and the earth surface subsidence. Such a situation not only affects the railway transportation but also endangers the safety of lives and property of the adjacent villagers. In this study, TEM served as the primary technique and IP sounding was used to strengthen the investigation along the railway. The location, limits and spatial characteristics of the gob areas were detected through the combination of the two methods. The accuracy of the investigation was increased and the effect was fine. The exploration results can provide reliable technical support for surface safety and gob treatment, and can also supply protection to railway operation.

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    THE APPLICATION OF GPR TO THE EXPLORATION OF KARST CAVES IN THE FOUNDATION OF BRIDGE TOWER AND ITS SIGNAL ANALYSIS
    YANG Tian-chun, FENG Jian-xin, WANG Zhan-jun
    Geophysical and Geochemical Exploration. 2011, 35 (2): 280-284.  
    Abstract   HTML   PDF (635KB) ( 836 )

    Horizontal karst caves were frequently studied for geohazards prospecting in the past. In this paper, the application of GPR to vertical karst caves was introduced in Zhangjiajie-Huayuan Expressway of Hunan Province, and the effectiveness of the complex signal analysis was illuminated in GPR data processing. A vertical karst cave characterized by a small horizontal scale would arose an unintelligible anomaly in the GPR image, which could not be recognized easily. The authors first processed the GPR data by two-dimensional spatial filter, and then applied Hilbert transform to the data, thus obtaining the transient amplitude, transient phase and transient frequency. Finally, the authors analyzed the processed data synthetically. The results show that the spatial filter can remarkably eliminate high frequency noise and improve SNR of the signal. In addition, the accuracy of the GPR interpretation can be improved by the multi-parameter analytical method. Drilling results prove the correctness of the inversion interpretation.

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