During the exploration of the underground medium structure, the gradiometer as well as its new deployment styles for various applications has become an important research topic of world concern. This paper describes various kinds of gradiometers based on torsion balance and difference algorithm and deals with the principle of each instrument. In addition, the absolute gradiometers based on the laser and atom interference are also described. In the last part of this paper, the design of the measurement light path is presented. The results obtained by the authors can serve as the technologic reference for developing gradiometer.

Using 1:25000 high precision aeromagnetic survey data and ground gravity data collected in eastern Hebei area,the authors analyzed the characteristics of magnetic and gravity anomalies on both sides of Lengkou fault and,in combination with the characteristics of geology and mineral resources,explained the factors responsible for the aeromagnetic and gravity anomalies and their control over geological structures and minerals. The characteristics of magnetic and gravity anomalies and the caprocks as well as the intrusive rocks are significantly different on the two sides of Langkou fault,so the authors infer that the fault not only controls the geological structure but also indirectly controls the distribution of minerals. The results obtained by the authors provide certain basis for geoscience research and mineral exploration.

In a gold mine of Tanzania, Sm-30 magnetic susceptibility device was used to directly measure the magnetic susceptibility values of drilling core rocks (ores) in the absence of logging equipment; the depths of the drill hole and the magnetic susceptibility values corresponding to these depths were plotted similar to well logs. According to the curve characteristics of the magnetic susceptibility parameters, the division of lithologic horizons was conducted, and the strike of the gold ore bed was determined. A comparison with the drill hole geological columnar section shows that this method is quite effective.

On the basis of the project of "China National Mineral Resources Potential Evaluation" and with the secondary development of regional geochemical data as a precondition, the authors generalized the halation and metallization geochemical and geological characteristics of some typical antimony deposits within the study area. In Rongjiang-Leishan area of Guizhou Province, the authors conducted geochemical quantitative prognosis of some antimony deposits in different geological units (the cap and the base formation). Similarity, metallization conditions, deposits distribution, elements composition and antimony anomaly intensity were selected as the prognostic variables, and some target areas around Rongjiang-Leishan were delineated. Furthermore, the potential resource of each target area was evaluated individually on the basis of analogy and areal productivity methods. The results provide geochemical data as reference for mineral potential evaluation.

Geological and geochemical background analysis shows that the Baoshan metallogenic belt has favorable metallogenic conditions and prospecting potential. Based on probing into the geological-geochemical characteristics and ore-forming regularity of the main large-size and medium-size Pb-Zn deposits, the authors put forward a "four zones, four storeys and three types" characteristics of Pb-Zn mineralization in the Baoshan metallogenic belt, which provides theoretical basis for geological-geochemical prognosis of regional Pb-Zn deposits. Based on analyzing the characteristics of four main Pb-Zn anomaly zones, this paper establishes prospecting models of the comprehensive information. The favorable zones for exploration and major types of ore deposits are pointed out, which is helpful to further ore-prospecting work.

In order to tap ore-prospecting potential in southeastern region of Guizhou, the authors interpreted regional gravity magnetic anomalies, studied distribution of gold geochemical anomalies in the Tianjinli gold ore concentration area of eastern region and western region and, as a result, discovered the regularity that the gold ore deposits (ore spots) and gold geochemical (element, block) anomalies are related spatially, temporally and genetically to the planar distribution of gravity and magnetic anomalies as well as the distribution of the inferred magmatic intrusions (basic, acid and tectonic alteration rocks) and the regional EW-trending and NS-trending deep and great faults. The results open up the new train of thought in search for gold deposits in the Tianjinli gold ore concentration area of eastern region as well as its periphery. The prospecting for veined gold deposits in metamorphic detrital rocks should not be confined only to the relevant horizons and the intersections between the NE-trending structure and the accompanied faults (i.e., anticline plus a cut) as well as their nearby places.

With the development of technology and the increasing difficulty in finding new shallow deposits, the single and traditional method can hardly meet the demand of finding new mineral resources. This paper made a case study of VLF and EH-4 in the exploration of the Xiaosijia fluorite deposit in Aohan Banner, Inner Mongolia. On the basis of geological survey, the authors applied VLF and EH4 method to the exploration of the Xiaosijia fluorite deposit. According to the results, the combining method of VLF and EH-4 is useful in the exploration of concealed fluorite deposits, the VLF survey can quickly define the distribution characteristics of structures with low resistance, and the EH-4 survey can reveal the deep distribution of structures with low resistance. The two methods can make their respective advantages complementary to each other and offer scientific foundation for the future exploration.

Two kinds of methods for geochemical exploration were carried out in the Zhunsujihua copper-molybdenum deposit of Inner Mongolia. The results show that anomalies delineated by fine particle total measurement and MOMEO are in accordance with the deep concealed ore bodies. It is thus known that the two kinds of method can indicate concealed copper-molybdenum deposits effectively and can also be used to search for concealed copper-molybdenum deposits on semi-arid grasslands.

Based on the acquisition and analysis of geological, geophysical and geochemical data of the Yanqian tungsten ore district in Changshan, the authors established the metallogenic model and ore prognostic model for mineral deposits of this type. In the Yanqian ore-forming prospective area, four minimum prognostic units were delineated, of which two units are Grade A prognostic units, and two units are Grade C prognostic units. In addition, MRAS software was employed to predict tungsten metal source quantity.

The Dapingzhang Cu-polymetallic deposit is a typical volcanic exhalative sedimentary deposit in western Yunnan. This paper has summarized the geophysical characteristics of the ore district and established the geophysical anomaly model for the Dapingzhang deposit in combination with the geological features, in the hope that the model can guide the prospecting work in the depth and on the periphery of the ore district. In this paper, the main geological features include IP intermediate gradient anomaly, IP sounding anomaly, high-frequency magnetotelluric method (EH-4) anomaly and Transient Electromagnetic Method (TEM) anomaly in the ore district.

This paper investigates the method of high-precision digital elevation model generation in gravity intermediate area topographic correction with ZY-3 stereo surveying satellite data. The rational function model has been refined with the GPS points and forward, nadir, backward image data. The experimental verification of topographic correction with 1:10 000 high-precision digital elevation model data shows that the digital elevation model produced by ZY-3 stereo data can meet the precision requirement for 1:200 000 gravity intermediate area topographic correction. The result obtained by the authors provides an effective means for gravity intermediate area topographic correction and expands the application of ZY-3 in regional gravity survey.

RES2DINV is a good processing software for multi-electrode resistivity method. It is widely used in the data processing of the multi-electrode resistivity method. The No. 938 Geological Party of Guangdong Nonferrous Metal Geological Bureau carried out DC IP sounding work in a lead-zinc mine of northern Guangdong Province. The authors modified the format of IP measurement data, used RES2DINV software for inversion and, on such a basis, inferred three ore bodies, which are basically consistent with the drilling results.

Wireless Electro-Magnetic Method(WEM)is a new artificial source electromagnetic sounding technique developed in the 1990s. In this paper, the origin of the harmonic of the transmitting electromagnetic signals in WEM was analyzed, and the apparent resistivity and phase were calculated by using transmitting signals and its harmonic with the data of experimentation. Based on a comparison of the two results, the authors considered that this technique is an effective method by using harmonic in the artificial source electromagnetic methods. It can improve work efficiency by decreasing transmitting frequency numbers or improve accuracy of interpretation by increasing frequency numbers of the electromagnetic response curves. This technique can be used in other artificial source electromagnetic methods because the harmonic always coexists with the transmitting electromagnetic signals in the source electromagnetic method.

This paper aims at obtaining a calculation equation for the formation porosity and natural gas hydrate content applied to Qilian Mountain permafrost area. Based on the laboratory test data of two cores, the authors adopted the multiple linear regression to get the porosity calculation equation applicably. And by referring to the relevant data obtained both in China and abroad, the mofified Archie Equation was employed to calculate the hydrate concentration and to get the concentration values of five hydrate formations with log data. A comparison with the value obtained from the univariate equation shows that the value from the ternary linear regression porosity equation can achieve better accuracy (up to 85%) with the test data of the core. The value range of the hydrate concentration is between 11.47% and 81.61%. The results obtained by the authors can provide valuable reference for the evaluation of the natural gas and hydrate in this area.

Advanced field experiment in electromagnetic exploration is of importance for performing geological projects and evaluating data interpretation. First, the measuring time is computed by geoelectric parameters, then the transmitting loop side and current could be determined according to the noise electric level. After the test of wave form, the measuring time will be confirmed through the geological effect experiment beside drill holes. Nevertheless, the signal-to-noise ratio, the coincidence and the stability should meet the requirements of prospecting accuracy.

This paper made a comparative study of the experimental devices for multi-turn small loop and discussed the variations of the parameters of two devices along with the turns of the loop, so as to provide the reference for field exploration. Firstly the authors buried a low resistive body at a certain depth and arranged a line above the low resistive body, and then analyzed the launch magnetic moment, the turn-off time, and the variation of the induced signal with the turns of the loop. On such a basis, the authors compared the multi-channel profile sections of different devices and analyzed their similarities and differences. Experimental results show that the launch magnetic moment, turn-off time, signal strength and resolution to the low resistive body increase with the turns of the loop; under the condition of the same turns, the launch magnetic moment and turn-off time of single loop are relatively large, the effective signal energy is attenuated quickly, the signal strength is relatively weak and the detecting depth is shallower. However, under the effective detecting depth, the resolution of the small single loop to the low resistive body is higher.

This paper deals with the effect of applying the metallic factor to the interpretation of IP anomalies in an ore district of Fuyan County, Xinjiang. Induced polarization method of geophysical electrical survey was employed to select electricity unusual areas, with the purpose of identifying the IP anomalies in the work area. The authors used the method of apparent metallic factor (J_s) by extracting IP secondary information to make prominent the low resistivity polarization anomalies and suppress the high resistivity polarization anomalies, thus strengthening the ore-related anomaly, suppressing the interference of barren anomalies, and successfully distinguishing ore-related anomalies from barren anomalies. Through calculating the dependency on the apparent metallic factors, the authors delineated the key exploration areas, and arranged IP sounding profiles in key exploration areas, thus guiding the drilling work. The drilling results has proved the effectiveness of the IP method in the exploration work of this area.

According to the results of 2-D resistivity inversion of magnetotelluric sounding, geological structures and strata were preliminarily confirmed. By synthetic analysis of petrophysical characteristics, the authors established the petrophysical parameters of strata and rocks in the study area, established the initial model of geology-geophysics, carried out gravity-magnetic-magnetotelluric joint inversion under the restraint of geological, well log and seismic data, and constantly revised the model of geology-geophysics and the results of 2-D resistivity inversion of magnetotelluric sounding, to make the gravity-magnetic measurement data fit in with the theoretical calculations. The results of interpretation of geological structures and strata in Yin'e basin show that the gravity-magnetic-magnetotelluric joint inversion can effectively overcome the multi-resolution of the single one, more correctly identify strata, and greatly improve the accuracy of quantitative interpretation.

Based on elastic wave equation,the authors deduced first-order velocity-stress elastic wave-equation with decoupling of compressional wave and shear wave and no converted wave under the condition of two-dimensional inhomogeneous media,which could not only make the implementation of vector migration and ensure the quality of migration,but also avoid the production of other kinds of converted interference wave.Starting from theories of exciting time image condition and reflection coefficient,in combination with first-order velocity-stress elastic wave-equation characterized by decoupling of compressional wave and shear wave and no converted wave,the authors put forward the image condition and migration method suitable for simulated data based on a combined P + S source.This paper has provided the theoretic record migration results of two typical models,and tests show that the method proposed in this paper can make the wavefiled produced by a combined P + S source return to the position accurately,and improve the processing precision of information.

Loess plateau with very complex geological conditions is considered to be a world-class thorny problem.Liupanshan basin in southern Ningxia belongs to the typical loess tableland geomorphology and sedimentary basin,and its exploration is of low degree but has great potential.Geological conditions of the area is very complex with a great thickness of loess layer covering the surface,and deep conditions in different tectonic units are very different,so we must overcome the double impact of surface and underground in the seismic acquisition.In this paper,in combination with the data available and the application of new technologies and new methods,the authors analyzed the areas with different geological conditions and the difficulties in exploration and, on such a basis, summed up a series of seismic acquisition technologies with the purpose of guiding the exploration work in this area.

Thin interbedded sandstone reservoir has such characteristics as great thickness,small monolayer control reserves and strong heterogeneity.If the conventional areal well pattern is used,the reservoir will have a poor overall development effect characterized by low reserves control degree,serious contradiction between layers,low recovery rate and poor economic feasibility.According to the sedimentologic features of the oil-bearing sand body,the method of vector well pattern placement in single sand body scale is established based on porous media seepage theory,and a well spacing design formula of vector well pattern for single sand body with areal heterogeneity is provided.On the basis of physical model developed by the provided well spacing design formula, the water/oil displacement experiment on planar models is launched.With the application of reservoir scale vector well pattern placement by reservoir numerical simulation,a specific development strategy of series of strata assemblage and well placement for superimposed area and non superimposed area of interbedded sandstone reservoir is established.

Based on a systematic analysis of geological and geochemical environment of Rizhao tea-producing area, the authors hold that terrain, geomorphology, soil physical and chemical properties and elements content have important effects on tea quality. The correlation between total soil elements quantity and tea quality is not obvious, but the abundance and deficiency of effective elements have great impact on the tea quality. When the content of the available N, SiO₂ is relatively high, he content of free amino acids, caffeine and total ash in the tea will be higher, and the tea quality will be also higher. When the pH value of the soil and the effective content of Ca, Mg are comparatively high, the content of free amino acids, caffeine and total ash, and flavonoids in the tea will decrease, and the quality of the tea will also decrease. The correlation between water extracts and most effective elements is relatively obvious. The results obtained by the authors provide the basis for programming of Rizhao green tea producing area and south-to-north tea transfer.

Spatial distribution characteristics of soil metals in Zhangye-Yongchang area of Gansu Province were studied in this paper. The results show that the study area is mainly characterized by the pollution of Cd, As, Cr and Ni. Industrial waste water and industrial enterprises, human activities and atmospheric dust constitute the major sources of soil pollution in the study area. Viewed from the comprehensive evaluation map of the degree of soil pollution, Grade one, Grade two, Grade three and Grade four quality areas possess 1.87%, 87.13%,9.92% and 1.09% of the total area respectively. The current situation of soil pollution shows that heavy metals pollution in soil is mainly of Grade one and Grade two, which suggests the fairly good overall quality of the soil in the study area. Phase state analytical results of Cd, As, Cr and Ni show that Cd, As, Cr and Ni are mainly characterized by residual fraction. However, the Cd element is characterized by bound and soluble fractions, which account for about 5% of the total amount, and this situation is dangerous and deserves much attention.

Based on soil pool-rich standard classification for selenium from "National A Layer Soil Background Cumulative Frequency Classification Method", the authors hold that selenium-rich soil exists in Fangshan District. Se content of soil from different physiognomies shows that the mean value of Se decreases in order of erosion accumulation platform, pluvial plain, alluvial-pluvial plain and alluvial plain, and the Se element is mostly concentrated in the top soil, and decreases rapidly toward the depth. The Se content of soil is considerably influenced by soil organic matter of mountain areas, whereas the meta-alkaline and organic matter-rich supergene environment helps to the enrichment of Se in soil. The selenium content of winter wheat and vegetations has good relationship with the soil selenium content, and is lower than the standard content stipulated in the National Specification of Food and Vegetation.

The audio magnetotelluric method has been widely used in the field of groundwater exploration both in China and abroad. In this paper, the groundwater exploration in a certain area of Northwest China was taken as an example. The theoretical basis of the method was elaborated and its application effect was discussed. As the equipment of audio magnetotelluric method is relatively light in weight, the exploration depth is relatively large, and hence the results are fairly satisfactory. Therefore this technology has a broad application prospect in groundwater exploration.

Based on an analysis of hydrogelogical conditions in southern Tongliao of Inner Mongolia, the authors inferred the distribution characteristics of the water quality and delineated the limits of soil salinization by using the airborne electromagnetic method(AEM) and the results of data conversion. The results of AEM exploration indicate that the re-salinized area is very insignificant, whereas the non-salinization area is very extensive; the groundwater resources of the northern plain area are rich and the Quaternary aquifer is a huge hosting space of interconnected groundwater with free surface.

The application of wave-form classification technology has several obvious advantages in identifying lithological faices.Nevertheless,its limitations are also existent.According to lots of practical applications in areas with different lithological facies,this paper deals explicitly with the factors affecting the application results.Also,the applicability and limitations of this technology in recognizing lithological faices have been analyzed systematically.Studies show that the type and length of time window and the selection of seismic attribute volume have the most significant influence on the utilization quality.In addition,the remarkable differences in seismic amplitude,frequency,phase,and time thickness of lithological facies constitute the fundamental basis for the appropriate use of the wave-form classification technology.When the seismic reflection responses between different lithologcial facies are not obvious,or the wave-forms change abruptly within the same lithological facies,the results have less geological meaning and are far from desirable.Focusing on the geophysical response features of lithological facies,establishing the relationship between seismic response and lithological facies and carrying out the trial application constitute the basic and crucial points for successful utilization of the wave-form classification technology.

In marine seismic survey,the difference of wave impedance between water bottom and surface is remarkable,and hence there are lots of short period multiple waves and micro-bending multiple waves in the marine seismic data,which affects seismic data quality seriously.Usually Surface Related Multiple Elimination(SRME)is used to suppress these multiple waves.In an area of Southwest Weizhou,the basement is shallow,and its wave impedance has considerable difference from the wave impedance of the old formation,so in addition to water bottom and surface there are the third multiple wave sources,and there is a water bottom multiple wave very close to that of the basement.Conventional SRME couldn't attenuate the multiple waves.The authors used series SRME based on wave equation model and convolution model to suppress them,and the result is obvious.

Based on an analysis and contrast of seismic curvature attributes,this paper aims at finding effective curvature attributes to interpret the seismic data so as to improve the efficiency and accuracy of interpretation.The amplitude curvature attribute and structural curvature attribute are independent of each other in mathematics.The amplitude curvature attribute can be computed by the second derivative of seismic amplitude data.Faults and geological anomalies in general seismic section have such features as variation of the homophase axis,twist,and abrupt change of the amplitude.These variations show small linear structure in the seismic horizon curvature attribute,so faults and geological anomalies can be interpreted according to linear structure anomaly.This paper also sums up the notable problems in the application of curvature attributes.Amplitude curvature attribute not only reflects structural characteristics but also highlights the difference between the amplitudes of geological factors,thus demonstrating the geological features.This technique can effectively portray boundaries of sedimentary bodies,hierarchical structure, and fracture system.The applications show that the utilization of amplitude curvature attributes is effective and convenient in interpreting faults.With this technique,the tracks of the faults and the sizes,shapes and boundaries of sedimentary bodies become continuous and clear, and the fault interpretation becomes more easy.

Data-processing plays an important role in the magnetotelluric (MT) sounding work. For several simultaneous sounding sites, in particular, it is required to process field data with magnetic remote reference, which is time-consuming and demands a huge amount of calculation. The professional processing software named SSMT-2000 is commonly used to carry out the work; nevertheless, because of the restriction of the software, the batch processing for data from several sites can't be carried out efficiently. Hence data-processing has become a tedious and long time work for MT workers. In this paper, the authors analyzed the format and the calling pattern of parameter files, probed into the problem as to how the internal executables are called by SSMT-2000 and, on such a basis, developed a smart code based on the MATLAB language. The code has the utilities of running a batch processing for fast Fourier transform, Robust estimation of impedance tensors for one single site and utilization of magnetic remote reference technique in three ways. The authors can apply the code to process data from many MT sounding sites at one time, which makes multiple-site data processing procedures much simpler and more efficient.

Although there are many methods to determine thresholds of geochemical anomaly, they all to some extent have such problems as complex calculation process, narrow application scope, and low popularity degree of professional software. Aimed at solving these problems, the authors put forward a method formed by the combination of EDA technique and classical statistical probability method. And a VBA program for this method is developed by using the Application Development Tools in Excel to realize the quick calculation of geochemical anomaly thresholds. This method and VBA program are characterized by simple and convenient calculation, robust anomaly thresholds and wide application range. Nevertheless, according to the principle of this method, it can only be applied to the data from a single parent body which can be recognized by fractal pictures.

Since July 1, 2008, the CGCS2000 Coordinate System has been employed in China; nevertheless, Beijing Coordinate System of 1954 remains its utilization in geological and mineral departments. For the purpose of realizing the effective sharing of graphic document achievements of different coordinate systems, the transformation of geological, geophysical and geochemical exploration graphic documents must be carried out in different coordinate systems. This paper describes the inter-conversion method of graphic document achievements in different coordinate systems by using MapGIS. The transformation precision was analyzed with the real data. The test result indicates that the method used in the graphic document transformation of different coordinate systems is completely feasible.

The shaded relief map can enhance the gradation and reality sense of the grid data, and the realistic three-dimensional grid data show the effect of the airborne geophysical interpretation of a wide range of integrated applications. Based on the principle of the drawing of the shaded relief map, the authors realized the drawing of the map, and compared the application effect between the image fusion and the image enhancement technique in the formation of the image. Through the application of the interpolation technology, the display technology and parallel algorithms can improve efficiency and ensure the display effect.

On the basis of the seismic reflection and fault characteristics,this paper deals with supertrace-based coherence-estimation technique for complex fault interpretation and the actualization of this technology.To include more seismic traces in the coherence estimation,this paper introduces a supertace technique that constructs a new data cube by rearranging several adjacent seismic traces into a single supertrace.And the cube preserves the dip information contained in the original data cube,and reduces average effect of seismic attributes computation.By combining the supertrace technique with the wavelet transform of seismic coherence technology, the coherence value is estimated.The method has very fast calculating speed and can effectively suppress Gaussian noise.The result shows that this method is significant in comparison with the routine method.It can effectively enhance the faults continuity,which is helpful to trace strata and explain faults.It is especially adapted to low SNR seismic data structure interpretation.

With the success examples of applying the transient electromagnetic method to detecting water-rich anomalous areas on the top and the floor of the main coal-mining bed in the southwestern ore district of Pingdingshan, this paper investigated the applying effect of PROTEM67D system in detecting geological bodies with the buried depth over 1000 m. It is held that, before the acquisition of the outwork data, the choice of suitable work parameters through test is the prerequisite and the important guarantee for fulfilling the exploration of the deep anomalous body.

Empirical mode decomposition has its unique advantages in dealing with non-linear,multi-component signal.Subjected to the sampling rate and the fact that frequencies of the individual components usually lie close to each other or within an octave,each intrinsic mode function is not composed of a single frequency component.With the help of the combination effect of masking signal and sampling rate interpolation,the result of intrinsic mode functions is significantly improved relative to the traditional EMD decomposition.The improved decomposed intrinsic mode functions are used to image the defects inside a concrete structure with the synthetic aperture focusing technique.The location of the defects can clearly be found,and practice has proved the feasibility of this improved method.