The preliminary study of the geochemical features in Buqingshan area of East Kunlun in Qinghai Province was based on the 1∶50000 stream sediment survey. The study included element distribution characteristics, element anomalies, element correlation and element anomaly assemblage. The result shows that the study area might be a prospective area for Au, Cu, Co, Ni and Sb. It is inferred that ore deposits in Buqingshan area are probably porphyry Cu-Au polymetallic deposits related to granite and granite porphyry, whereas Co-Ni polymetallic deposits are related to the basic and ultrabasic rocks. The Mnite area is expected to be a prospective area for porphyry Cu-Au polymetallic deposits, the Delisitan area is likely to have Co-Ni polymetallic deposits associated with basic and ultrabasic rocks, and the Gerizhuoduo area is expected to be a prospective area for porphyry Cu-Au polymetallic deposits.

Through a comparative analysis of aeromagnetic data, detailed ground magnetic data, drilling validation data and regional gravity data obtained from the Sigezhuang work area of Luannan County in Hebei Province, this paper has made a preliminary summary of characteristics and regularity of the gravity and magnetic field in deep buried iron ore deposits. In practice, the authors actively explored Jidong metamorphosed sedimentary iron deposits with the purpose of looking for deep concealed large ore deposits based on new ideas and new methods, and the result obtained has great significance in search for deep and blind iron ore deposits in the future.

The Taipinggou stream sediment anomaly was delineated by the new regional geochemical exploration method for forest-swamp landscape region. Three-grade verification showed that it is an ore-related anomaly with good ore-prospecting vista. A medium-size porphyry molybdenite deposit was discovered in successive exploration, which fully shows the ore-prospecting guiding role of the regional geochemical information and the effectiveness of the new regional geochemical exploration method for forest-swamp landscape region. The authors conducted a study of the distribution of the Taipinggou geochemical field, extracted anomaly information by using optimum residual anomaly method, analyzed anomaly characteristics, and investigated ore-prospecting orientation.

Through 1∶50 000 stream sediment survey, multi-element anomalies were delineated in Yelanggou, which included Ag, Mo, W, Zn, Bi, As, Sb, Au, Cu etc. Of all these elements, Ag, Mo, Zn, W, As and Sb anomalies have high peaks, high values and continuity. The mixed anomalies are controlled obviously by faults and folds, characterized especially by high values in well developed fault tectonic alteration zone. Areas of lithogeochemical anomalies of indicator elements are not large; nevertheless, the intensity of principal ore-forming element Zn is high, as shown by Zn11 primary halo. The area of Zn11 primary halo is 0.11 km², the geometric mean is 1 368.51×10^-6, and data of three continuous samples are all above 3 000×10^-6, so this primary halo is identified as an anomaly related to mineralization. Zn, Ag and As primary halos have larger sizes and are more continuous around the mineralization district than in other places of the study area. All these results are really important for the study of ore-forming process and prospecting work.

The magnetic anomalies were delineated and the direct magnetic data were obtained by the ground magnetic survey in the Songhu iron deposit. On the basis of an analysis of reduction-to-pole of magnetic data and upward continuation,four high magnetic anomaly areas were delineated. Through the utilization of the 2.5° gravity and magnetic anomalies for iron deposit characteristics by fitting a curve of 2-dimensional interactive inversion,the relative depth of the high anomaly area was analyzed. The result has provided geophysical foundation for mineral prospecting.

An investigation of Longyao buried fault through the survey of radon in soil was conducted using FD-3017RaA emanometer. Through data processing and comparative analysis,the distribution range of the concealed fault in ground has been determined more accurately,which provides a valuable reference for further researches using other means.

The CSAMT method was used to conduct exploration of concealed ore bodies in the Shishi-Beiye ore district of Xin'an County, Henan Province. The results show that this method can be used to perform inversion of paleo-landform of Ordovician limestone, infer occurrence space of ore-bearing rock series, and predict potential resource quantity of bauxite. With this method, the exploration depth is relatively great, thus meeting the requirement of deep bauxite detection. The resistivity contour lines of the section of CSAMT can quite clearly reflect the attitude of strata, and hence the resistivity values can be used to divide strata.

Peru is rich in iron ore resources. Aeromagnetic is an important approach for iron deposit prospecting directly or indirectly. In order to understand distribution of iron bodies by using aeromagnetic information, various data process approaches such as reduction to the pole, continuation and derivative have been carried out for the 2 250 000 km² aeromagnetic raw data. Combined with regional geological structure and geological strata and lithology of Peru, various magnetic anomalies concerned with iron ore types are selected. The anomalies include: anomalies induced by continental facies eruption;the magnetic anomalies which are controlled by faults and concerned with the volcanic eruptions in early and middle Tertiary;the anomalies induced by the early and middle Tertiary volcanic eruptions covered areas;the positive magnetic anomalies belt induced by the coast rock band;anomalies induced by post-magmatic hydrothermal iron ore vein located in diorite rock;skarn iron ore anomalies.

In deep-penetrating geochemical international cooperative project, results obtained by sequential extraction methods for mobile forms with ultra filtration technology of China and six selective leach methods of Canadian labs showed fairly good anomaly over the Spence porphyry copper deposit in Chile. In order to identify the type of anomaly, the authors extracted and tested industrial mineral phase of Cu. The results show that Cu of oxide and sulfide phases has fairly ideal anomaly discrimination over the ore body. It can thus be confirmed that the above-mentioned anomaly is an ore-induced anomaly. The authors believe that, for underlying porphyry copper ore deposits such as Spence, trace phase analytical method technology should be used to look for industrial mineral anomaly after finding element anomaly by deep-penetrating geochemical methods. If the two kinds of anomalies coincide with each other, researchers can more confidently make a correct assessment of ther concealed ore body.

The utilization of the vertical component ΔZ and the rational horizontal component module difference ΔH' value to conduct 2D fitting inverse calculation and subsequent inference and interpretation can effectively detect the mode of occurrence of the borehole lateral magnetic body. This interpretation method can play an accurate guiding role in search for deep magnetic ore bodies. The application of this technology to deep prospecting is of great geological significance.

China Aero Geophysical Survey and Remote Sensing Center successfully developed AGS-863 Three Axis Airborne Magnetic Gradiometer with self-owned intellectual property rights, and carried out gradient measurements of aeromagnetic survey in Inner Mongolia recently. To analyze the key indicators of gradiometer and corroborate instrument performance, the authors designed the testing method for key indicators. It has been proved that the aeromagnetic gradiometer is stable and reliable during survey. The test result shows that the system has excellent synchronism, consistency, long-term stability and compensation precision.

This paper analyzed the twin-T notch filter circuit, deduced the expressions of transfer function, center frequency, bandwidth and Q value. Through calculation, analysis and simulation, the optimal resistance and capacitance were selected for the characteristics of wide field electromagnetic signal and the suppression requirements of frequency interference. Experiments show that the optimal design of twin-T notch filter's minimum depth of suppression is -31.9 dB when the bandwidth is only 3.62, so the application of the optimal design of twin-T notch filter can not only keep the desired signal, but also maximally filter out frequency and its harmonic interference noise in the wide field electromagnetometer.

Using three-point deconvolution calculation principle, the authors analyzed responsiveness of characteristic parameter α, calculation features of the cell layer, and the causes for appearance of negative values in the anomaly section. The authors hold that, in the quantitative interpretation of γ logging data for the granite-type uranium deposit, it is relatively reasonable to choose the value 0.1 of characteristic parameter α for calculating the ore bed thickness and uranium content, which can remarkably simplify the calculation process.

From the viewpoint of chemical composition categorization and structure classification of rocks, an effective method was proposed to identify the lithology of volcanic rocks by using logging data. On the one hand, the conventional logging data could be obtained by core wafer identification. Thus, after processing the data with Support Vector Machines (SVM) method of statistical theory, we could get the lithologic type of the volcanic rocks, which are classified according to the chemical composition of rocks. On the other hand, the volcanic rocks can be classified as volcanic lava, pyroclastic lava and pyroclastic rock according to the rock structure. Typical formation micro-resistivity imaging logging (FMI) image mode can be concluded by establishing the corresponding relationship between FMI images and lithology of volcanic rocks with different structures. As a result, the lithologic type of the volcanic rock classified by rock structure can be determined. Finally, by combining these two kinds of lithology, the ultimate rock lithology can be determined, too. In this paper, the authors presented a novel method to identify the lithology of volcanic rocks by combining SVM processed logging data and FMI image mode.

The exploration of permafrost thickness refers to determining the upper and the lower limits of frozen soil depth. According to the geophysical properties of permafrost, frozen and non-frozen soils show significant differences in the permittivity and resistivity . Using ground penetrating radar (GPR) and transient electromagnetic sounding method (TEM) respectively, the authors explored the upper and the lower limits of permafrost in hot spring areas of eastern Tibetan Plateau. The results show that GPR and TEM can effectively solve the above problems. It is concluded that applying GPR and TEM is a set of feasible methods for the exploration of permafrost thickness in the range of 0 ~ 100 m in depth.

In recent years, pre-stack time migration has developed rapidly in various fields. The composite reservoir in the Tahe oilfield is complicated in type of hydrocarbon trap, thin in reservoir thickness, low in amplitude of structure, laterally variable in lithology, and strong in heterogeneity. Compared with poststack time migration and conventional bend-ray Kirochhoff pre-stack time migration, the imaging resulting from asymmetric travel time Kirochhoff pre-stack time migration is clearer in images of faults, breakpoints, planes of unconformity and reflector structures in the Ordovician carbonate reservoir. The lateral resolution of the stack section is improved.

Karst collapse is widespread in the coal field of northern China, which takes a serious influence on the designing and production of mine well. On the basis of establishing the forward model, this article made use of migrate result of model data to extract and analyze the seismic attribute. Some analysis and contrast indicate that the lateral scale of karst cave reacts well in the attributes of amplitude class, frequency class, and phase class. The vertical scale can be quantitated by the spectral decomposition attribute.

This paper deals with the problem of "acquisition footprint" in recording geometry. The effect of "acquisition footprint" on the seismic attributes and reservoir prediction was first analyzed, and then the self-adaptive filtering method was used to eliminate the "acquisition footprint", thus inhibiting the interference of "acquisition footprint" in the post-stack seismic data. Based on an analysis of the effects on seismic attributes and reservoir prediction before and after eliminating the "acquisition footprint", the authors put forward a method for eliminating acquisition footprint.

Based on analyzing the actually measured MT data of an ore concentration area in the middle and lower reaches of the Yangtze River and considering the actual situation in the study area, this paper analyzed the profile characteristics of noise and divided the noise into 6 kinds, namely, impulse noise, periodic noise, triangle-wave noise, square-wave noise, step noise and triangular charge-discharge mode noise. The results obtained are helpful to making de-noising treatments directed against different noise types in the late-stage data processing.

Using the electromagnetic field stimulated by the horizontal electric dipole, this paper proposes the method of CSAMT near-field correction. According to the experiments, the result of this method is equivalent to that of the Cagniard resistivity in the distant area; nevertheless, the utilization of this method can obviously improve the distortion of the Cagniard resistivity in the near and transitional area. Therefore, this method will increase the depth of CSAMT exploration, extend the application field and reflect the changes of the vertical subsurface electric vividly.

Considering the P-impedance overlap of sand-shale, the faint AVO response and the complex reservoir conditions at the target zone in LHK field, the authors applied the pre-stack elastic parameters to predicting the distribution of hydrocarbon. This technique system includes three critical steps, i.e., filtering of sensitive parameters by analysis of fluid substitution and elastic parameters cross-plot, wavelet estimation in different partial stacks and fine synthetic seismogram correlation, and elastic parameters inversion and computation. The result of the intersection of lam*density body with P-impedance body can describe hydrocarbon distribution, which has been proved by drilling.

Within the limits of 13 000 km² in Yantai of Shandong Province, totally 408 top soil samples were collected with the density of one sample/36 km², and 10 indices such as HCH and DDT were determined. By studying the variation of the content, the authors have found that the soil has remaining HCH and DDT whose use has been prohibited for nearly 30 years, and some samples have relatively high content. According to environmental quality standard for soils evaluation, Ⅲ grade and Ⅲ-exceeding grade soils appear in the study area. In addition to α-HCH, β-HCH has the most high content in the four isomers of HCH , and DDT mainly existent in the forms of P,P'-DDE and P,P'-DDT. Furthermore, indicated by the changing rule of w(α-HCH)/w(γ-HCH),w(β-HCH)/w(γ-HCH)and/w(P,P'-DDT), the authors have induced that HCH has been used for a long time within the study area, and locally there doesn't exist new pollutant source input. In most areas, the use of DDT was stopped long time ago, and their compositions have undergone considerable change through physical and chemical actions, so the pollutant must have been formed in the past. In 4.41% of the study area, there may exist new pollutant source input in recent years, to which we must pay sufficient attention.

Using the multi-objective geochemical survey data obtained from Langfang, the authors studied enrichment characteristics and pollution degrees of As, Cd, Pb, Cr and Hg, which are five kinds of heavy metal elements in surface soil. Also, the five kinds of heavy metals were comparatively investigated with the quality evaluation method. The single factor index method indicates that Cd causes rather heavy pollution. Geoaccumulation index of pollution evaluation shows that, viewed from the background value of soil heavy metals, Cd causes mild-moderate pollution, while viewed from the background value of the study area, Hg causes mild-moderate pollution, whereas As, Cd, Cr, Pb do not cause pollution.

The landfill leakage pollution has been increasingly serious, and the groundwater pollution has especially attracted more and more attention among researchers. Based on the characteristics of landfill leakage pollution, this paper has studied the application of high-density resistivity method to landfill leakage detection, and proposed a set of work modes and techniques with high-precision. As proved by practical application, the high-density resistivity method for detection of landfill leakage is an effective method deserving popularization.

Based on two-dimensional Fourier transform and half-wave theory, this paper has studied the seismic Rayleigh wave dispersion curve extraction in f-k domain and made this theory fit in with a program by means of Delphi7.0. It is concluded that the f-k method overcomes the shortcomings of the one-dimensional digital processing technology and makes full use of multi-channel Rayleigh wave data record.

The magnetic field of pulse source in the cased hole was analyzed by the finite element method. The effect of relative magnetic permeability of casing, casing thickness and the pulse width on the magnetic field distribution was discussed. The magnetic field in pulsed cased hole is considered as two parts in time domain: early signal and late signal. The early signal decreases obviously and includes mainly the useless signals and high frequency part of useful signal. The late signal is the low frequency part of useful signal and decreases slowly, thus containing the information of strata. The magnetic intensity is small when relative magnetic permeability of casing is very large. When the relative magnetic permeability of casing is small, the magnetic intensity is large but decreases drastically. The measurement is more favorable for the moderate relative magnetic permeability of casing.

In the light of the characteristics of AMT data, this paper deals with the commonly used data processing methods for improving the vertical resolution, removing noise and suppressing the static effect as well as their characteristics. According to the quality of the raw data and the geological problems to be solved, we should choose different processing and inversion methods as well as their combinations in practice so as to get true and reliable formation resistivity values. Two means are also described in this paper concerning the formulation of mathematical models of groundwater salinity evaluation for pore formation, with some relevant application examples provided. It is concluded that different geophysical methods and different inversion methods will result in differences in formation resistivity values. While using the same mathematical evaluation model for salinity in the same work area, we should pay attention to the consistency of the working methods and inversion methods and make full use of existing data as well as choose appropriate methods to establish salinity assessment mathematical model based on the reality.

This paper analyzed the geophysical mechanism of the time-lapse seism and the non-geological factors responsible for the differences of the time-lapse seismic data, and dealt with the key processing technology for the marine time-lapse seismic data acquired on cable. Practical applications show that these technologies can improve the consistency of the seismic data processing results and improve the reliability of the difference profile, thus providing accurate information for the reservoir development monitoring.

In large scale gravity prospecting, when total accuracy of Bouguer gravity anomaly is increased to 0.025×10^-5m/s², the height mean square error of the measuring point must be 0.050 m. Using EGM2008 model and GPS leveling data to fit local quasi-geodic surface, the authors transformed the altitude of the measuring point GPS, thus reaching the accuracy. By using GPS leveling data of a certain area, the authors studied the feasibility of the transforming method. The result shows that the method is completely applicable to large scale gravity prospecting.

Based on analyzing Surfer data format, the authors compiled the procedure for topographic correction. The topography could be corrected on the original presumed sectional drawing for plane observation, and thus the observation plane can be expressed in the form of practical elevation curved face, so as to attain the effect of being closer to the reality. The topographic correction on the sectional drawing is of symbolic significance. After topographic correction, the spatial shapes of anomalies and the spatial relationship of various anomalies can be more easily and objectively observed; meanwhile, the sectional drawing will become more beautiful and have higher practical indicating significance.

Exemplified by the fathoming data of a survey line using direct current, the sectional drawings of apparent resistivity isograms were plotted by manual and Surfer software respectively. It is concluded that the plotting of the isograms by correct utilization of Surfer software is of great importance. The key points for an ideal effect include the presentation of the x and y value before mesh generation, the choice of the interpolation methods and the correct interpolation. If the plotting is incorrect, the explanation of the data can be directly affected and even a wrong conclusion will be reached.

The transport engineering has massive tunnel construction, and the tunnel construction is likely to be affected by adverse geological structures. In order to reduce the influence of geological disaster on tunnel construction, researchers use the TSP203 geological forecast system to carry out the survey in front of the tunnel face and provide in advance geological prediction that could give instructions for the following construction; nevertheless, due to the existence of much misinformation in the practical application, these means often fail to report the situation or the accurate of the report is too low. These problems often result from the insufficient data acquisition and data processing. Through standard data acquisition and reasonable data processing, the adverse effect might be reduced, and the application accuracy of the TSP203 system in the geological forecast could be improved.