According to the classification definition standard of soil selenium amount put forward by Li Jiaxi, it is confirmed that there exists selenium-rich soil in Zhejiang. Red earth in some areas and rice soil are important forms of selenium-rich soil in Zhejiang. The organic combination state in selenium-rich red earth and that in rice soil are the main combination patterns. The amount of weakly organic selenium is higher than that of strongly organic selenium in selenium-rich red earth, and the amount of ion exchange state selenium is lower than that of carbonate, but things are opposite in the latter case. The total amount of ion exchange state, carbonate state and ferric-manganese oxidation state has very little effects on full selenium.

Based on 1:200 000 regional geochemical exploration data obtained from the northern part of the Sanjiang region in combination with regional geochemical background,this paper has analyzed fairly in detail geochemical characteristics of various ages of strata and intrusive bodies.The metallogenic elements in this region are mainly As,Au,Cd,Hg,Ni,Sb,Ag,Cr,Pb,Sn,W,Zn and Cu.Such elements as Ag,Pb,Sn,Cd and Zn in the intrusive bodies are chiefly related to intermediate-basic volcanic activities,while the ore-forming actions of Cu,Mo,Bi and Au have close relationship with intermediate-acid magmatic activities.Cenozoic strata contain higher Cu than intrusive bodies of that age,and Mesozoic intrusive bodies contain much more Au than intrusive bodies of other epochs.These strata and intrusive bodies are therefore most likely to act as sources of ore materials.

Based on an investigation into 1:200 000 regional gravity field in northwest Hebei, this paper deals with characteristics of the regional gravity field and, according to inference and interpretation of regional fault structures, puts forward some new understanding concerning the main structures. The three NW-trending faults, namely, Kangbao-Chicheng-Miyun fault (F₁₁), Zhangbei-Zhangjiakou-Huailai-Changping fault (F₄₇) and Wanquanyulingou-Zhuoludaolazui fault (F₄₈), were recognized on the basis of gravitational and magnetic information. The EW-trending Kangbao-Guyuan, Chongli-Chicheng and Tanzhen-Miyun faults, NE-trending Zhangbei-Guyuan and Huailai-Shanghuangqi faults, and NW-trending Lanchengzi-Longmensuo, Zhangbei-Shahe and Yulingou-Nanliushui faults constitute deep fractural framework of this area.

Different lithological rocks have different content of radio-elements such as uranium,thorium and potassium.Even if they are the same lithological rocks,as a result of different cases and age of formation, different geological evolvement process, their content of radio-elements also is different .According to this character of radio-elements in rocks,using airborne gamma-ray spectrometric data,using the statistical multi-analysis methods,this paper analyzes airborne gamma-ray spectrometric data,makes out dynamic cluster chart, compares with geological map, compartmentalizes geological element, then offers some gist for the next geological work in this area.

Systematic investigations were conducted on the rock samples collected from the Ruqigou coalfield in Ningxia.As the rock temperatures vary with the combustion degree,the authors made a serial of calefaction experiments on the rock samples.The results demonstrate that the rock magnetism varies with temperature.The feasibility of applying the magnetic method to detecting the underground coal fires was studied and,in addition,the human-computer interactive inversion algorithm was used to process the measured data.The inversion result fits the measured data well and can determine the combustion center and delineate the coal fire area effectively.

In the Xiaotazigou gold deposit, Ba, As, Sb, Hg and Pb belong to the frontal halo elements, Mo, Co and Ni to the rear halo elements, and Bi, Ag, Cu and Zn to the main elements. The content of Na₂O in the lode increases with depth while the content of TFeO decreases. The linear equation formulated on the basis of fitting of such relationships can be used to predict the lode depth. In some large and high grade lodes, the temperature of the quartz fluid inclusions changes greatly (160～400 ℃),and so does the salinity of fluids (0～9%). In some relatively small lodes, the ore-forming temperature is higher(280～400 ℃) and the salinity is lower(<5%). In the deep part of the ore body, the quantities of the inclusions decrease obviously, the mineralizing temperature gets higher and the salinity of the fluids gets lower. Based on the prospecting criteria, it seems that no more industrial ore bodies are likely to be found below the level 19 in No.1 lode, and that No.2 lode probably has more potential than No.5 and No.6 lodes. The area 1-3 km south of the Beidashan monzonitic granite is the most favorable place in search for new, parallel and high-grade ore bodies.

Bauxite and ore-bearing rocks are different obviously from underlying limestone in electrical properties, and this constitutes the basis of applying the transient electromagnetic method to the exploration of bauxite deposits. The little-loop transient electromagnetic equipment was used in the Hucun bauxite deposit and some other deposits. Characteristics of the inversion anomalies were studied. It is shown that the high resistivity is caused by the basement limestone in the bauxite-bearing strata. The predicted interface of high resistivity is identical with the basement limestone interface controlled by drill holes.

In this paper, the metallogenic geological background, ore-controlling factors and characteristics of the typical deposits in the Banpo antimony orefield are summarized, and the rock and fault structures in relation to antimony mineralization as well as the distribution of trace and REE elements in strata are analyzed. In addition, the metallogenic fluid characteristics, the ore genesis, the metallogenic model and the prospecting indicators are discussed.

The Zhaishang gold deposit is a large-size gold deposit in West Qinling area. The ore bodies occur in the shatter zone of Devonian and Permian strata and contain rich metallic sulfides. To extend the gold ore district, the authors used IP medium gradient survey to delineate the polarizability anomalies, IP combined profile to infer the strike and extension of the shatter zone and metallic sulfides, and the compound polar distance combined profile and IP sounding to judge the dip and downward extension. Drill holes of ZK192, ZK112 and ZK42 were arranged. The inferred ore conditions in the ZK432 hole are coincident with the real conditions, showing satisfactory results.

Aromatic hydrocarbons are important components in crude oil and source rock. Aromatic hydrocarbon compounds which are complex and stable may be used to make the oil/source contrast and recognize the oil and gas properties, and can also serve as primary indicators to the existence of oil and gas in geochemical prospecting for oil and gas. Three-dimensional fluorescent spectrum of a graph has the feature of "finger-print". Samples with different properties are different in three-dimensional fluorescent spectrum parameters, whereas the parameters of the samples from the same source have many common properties. Three-dimensional fluorescent spectra have a good indicative significance to the properties of oil and gas by analysis of the surface samples in some prospect areas.The oil and gas properties of the trap in depth may be inferred based on three-dimensional fluorescent spectra. Three-dimensional fluorescent spectrum is an effective indicator to oil and gas migration and properties for oil and gas surface geochemical prospecting.

The traditional height corrections for airborne gamma energy measurement in undulated mountain areas frequently lead to considerable errors. The authors hence put forward a method for synchronous correction of flight height and landform, which is rapid and easy to operate and can thus solve the above trouble.

On the basis of previous researches, an equation for radon movement in Quaternary overburden over the fault has been established on the assumption that the overburden is stable. The boundary conditions are given in this paper. The numerical simulation of radon distribution in the overburden and the influencing factors are discussed. It is shown that there exists an obvious anomaly in the overburden over a fault, and its distribution is affected by the thickness of the overburden, the width of the fault, the diffusion coefficient of radon, and the convection velocity of radon.

The high precision electrostatic accelerometer is one of the key payloads for Earth's gravitational satellite, and its sensitivity parameters directly determine the non-conservative force measurement, and eventually affect the precision of the Earth's gravitational field recovery. In this paper, the in-orbit gravitational calibration of the high precision space electrostatic accelerometer is discussed. A theoretical analysis shows that the two high sensitive axes of the SuperSTAR accelerometer with a resolution of 10^-10 m/s² used in GRACE mission can be calibrated by rotating a spherical attracting mass with a turn table.

This paper describes the history and development trend of MPOG and sums up the theoretical basis of this technique. Examples of Songzi area in Hubei and Huhe depression in Inner Mongolia are given. MPOG has aroused more and more interest among petroleum exploration workers all over the world in that it is direct, effective, rapid and economical.

Based on lithologic logging interpretation, the authors identified typical fracture sections according to their logging response calibrated by core data integrating drilling mud leakage, drilling break and production data. Then the typical logging response of fracture section was employed as training samples for Artificial Neural Network Pattern Recognition (NNPR). All the 76 wells in the Qijia buried hill were processed by applying the ability of NNPR including paralleling process, distribution information storage, powerful self-study and automatic weight value adjustment. Finally, a new fracture prediction method integrating core, conventional logging, test and production data was formulated, which has been proved to be effective by drilling.

This paper deals with the first arrival batch modification methods which use the common-offset first arrival curve combined with the common-source-location basis by setting different parameters aiming at overestimation and underestimation of first arrivals. It also presents a new approach to the automatic picking of the later phase of the first arrival rather than the first break using a trough-to-peak ratio technique combined with expected arrival time, picking window and threshold. The application of these new methods remarkably improves the precision and efficiency of the first arrivals picking in areas of poor signal-to-noise ratios.

As a time-frequency decomposition method,the wavelet package transform can be used extensively. It is better than the wavelet transform. The wavelet package transform can divide the seismic data in more detail and better describe the distribution of effective wave and surface wave in the time-space field with the same frequency compared with the conventional Fourier transform. In addition, we can separate the surface waves from it. After reconstruction we can get the result of surface wave separation. The new method can separate surface waves successfully,and meanwhile it can also avoid the loss of the effective wave energy (particularly the low frequency energy),preserve the frequency band width of signal and raise the signal/noise ratio of the seismic data. Practice shows that it is very effective in surface wave separation.

Based on some suppositions on ideal electromagnetic analogy conditions, this paper analyzed the theoretical expression for the time domain IP field intermediate gradient method. The frequency domain data-processing method of the gravity magnetic field was employed to interpret the IP data, and some practical examples were used to make calculation, in the hope that the train of thought and method for IP exploration interpretation can be broadened.

This paper used the formula of layer system offsetting and stress recurrence in the calculation of solid multilayer elastic media. The formulae for calculating reflection and transmission coefficients of P and S-wave can be deduced. This paper tried to calculate several models for an oil field in Xinjiang and discuss the variation of the reflection coefficient with the incident angle. It is shown that the sand with gas is likely to be detected. Using Zoepptitz's equation and the resolution of reflection coefficients of upright incident angle, the authors tested the single interface and the model in this paper respectively, and the results are coincident with each other.

In developing the electrical method information interpretive system, the VB and Fortran mixed language programming has remarkable merits. On the one hand, we can use sufficient Fortran source codes and avoid the waste of resources. On the other hand, VB can get rid of the disadvantages of the Fortran, such as the untidy interface and unsatisfactory graphic processing function. This paper describes the transfer between VB and Fortran in detail and gives an example of mixed language programming with VB and Fortran.

Ground Penetrating Radar (GPR) has been widely applied in civil engineering and environmental detection as a high resolution and efficient nondestructive testing (NDT) method. For example, it is used to detect the rebar concrete structures. In this paper, the FDTD method was used to simulate the GPR detection of the defects in the reinforced concrete and to migrate with the frequency wavenumber (F-K) migration method. This study shows that the technique can be used to reduce the multiple and diffraction of rebar. With the F-K migration method, the diffraction energy is efficiently focused on rebar and defects, which can not only separate the signals of rebar from those of defects but also improve range resolution. As a result, the distribution and shape of defects can be easily interpreted.

In this paper, the authors deal with the basic principle for nondestructive test of the pile inclination. Based on the implementation of the seismic alignment on the top of the pile, it is found that the larger the inclination degree of the pile, the bigger its side effect, and that, when the pile is inclined, the main response on the side of the pile is the primary wave and the transverse wave. An experiment on the pile inclination with the help of a three-component detector has proved these conclusions.