From the practical need of scientific research, the authors put forward the concept of "eco-geochemical reference field". On the basis of this concept, this paper has discussed the concept and meaning of the soil eco-geochemical reference value. With the experimental result of the Zhangzhou study area as an example, the relevant relationship method was used to define the soil eco-geochemical reference value, which has provided a train of thought or a reference case for other relevant research work.

Considering the practical requirement in scientific research and adopting the tracing method for REE distribution patterns, the authors carried out a systematic research on the distribution patterns of REE in soils of alluvial plain. The results show that distribution patterns of REE in soil of alluvial plain are on the whole similar to each other, and that the basic characteristics of soil materials in alluvial plain are generally identical. Some insignificant differences in REE distribution patterns could be used to distinguish characteristics of soil materials.

Based on analyzing the data of some elements (including lead) and lead abundance ratio in air dust near the ground surface in Chengdu City, this paper has reached the conclusion that lead pollution is heavy. The spatial distribution of aerosol lead varies remarkably in the range from 119.76×10^-6 to 1327.42×10^-6 with an average of 374.51×10^-6, SD of 273.36 and CV of 0.730. The radiogenic lead of coal fly ash is obviously higher than that of gasoline and diesel oil, which can serve as the discrimination criterion to distinguish the aerosol lead sources. The data of lead isotopic compositions of aerosol lead show that the pollution is caused by multiple pollution sources, with the relatively clean area mainly by construction and soil dust, the moderately polluted area chiefly by automotive emissions and dust, and the heavily polluted area predominantly by coal fly ash, automotive emissions and industrial pollutions.

Based on the data of the Chinese chestnut yield of Qianxi County in 2001 and contents of 42 elements in stream sediments obtained from regional geochemical exploration, the authors sifted significant correlation variables and established the regression equation between element contents and Chinese chestnut yield. In the light of the natural landscape conditions,this paper has inferred the expected yield of Jingdong Chinese chestnut,and indicated favorable and unfavorable areas for producing Jingdong Chinese chestnut, thus guiding regional rational arrangement of Chinese chestnut production.

The NW-trending tectonic belts in the world are called Tethyan gigantic linear tectonics. The NW-trending structures along Poluokenu Qilian Mountains Qinling are well developed, making up an important set of ore-controlling structures. Based on 1:200 000 regional gravity survey in northwestern Hebei, this paper has discussed the geophysical (gravity field and magnetic field) evidence and its role in locating important mineral resources. Among the faulted structures, Kangbao Chicheng Miyun rift is the best ore-forming zone for lead, zinc and silver deposits, Zhangbei Zhangjiakou Huailai Changping rift is an active earthquake zone, and Wanquanyulingou Zhuoludaolazui rift may be an important boundary of geotectonic units.

The materials filled in the cave of conglomerate, part of cemented materials of sandstone and fresh rocks of sandstone were analyzed by magnetic susceptibility values, carbon 14, magnetic iron mineral content and ¹⁸O isotope. It is concluded that the magnetic susceptibility values of the Jiangbei conglomerate in Fuzhong of Beibei are consistent with the content of magnetic iron mineral. The characteristics of the magnetic susceptibility curve are similar to those of the oxygen isotope curve. The magnetic susceptibility of Jiangbei conglomerate in Fuzhong of Beibei can indicate the ancient climate change: the last stage of last pleistocene epoch experienced two relatively short warm-humid periods and three comparatively long dry-cool periods, but in the dry-cool periods there exists very short warm-humid time.

Hydrocarbon prospect appraisal by trace element spectral diagram is a new geochemical technique,developed on the basis of Russian geoelectrochemical exploration methods. Field tests show that spectral diagrams of electrochemically extracted trace elements Ti、V、Cr、Mn、Co、Ni、Cu、Zn in soil samples from within and outside oil production area have distinct characteristics. Based on these differences of spectral diagrams of trace elements in soil samples and the correlation coefficients of the spectral diagrams with standard soil sample from oil-bearing area, the hydrocarbon prospects of the study area can be evaluated and delineated. By the correlation coefficient anomalies of trace element spectral diagram in soil samples one oil-bearing prospect in Wugucheng area, which is in consistent with results of alkane geochemical analysis and self-potential anomaly and audio-frequency magneto-telluric anomaly, and 3 oil-bearing prospects in Jiyuan area are predicted. In 2001 and 2002 the predicted oil-bearing prospects were verified by the following drilling wells.

In view of the particularity and complexity of the subtle hydrocarbon reservoir in the west slope area of Qinan, the authors pointed out the difficulties in litho-reservoir exploration and provided the solutions according to the basic methods of the modern reservoir description. First, on the basis of improving resolution of seismic data, the strata were divided by utilizing sequence stratigraphy technique, and the object units of description were identified successfully.Second, the subtle structure features which existed in thin beds were detected accurately by applying several advanced techniques of structural interpretation, such as dominant band coherence processing and dip and azimuth angle composite detection that can identify small faults. Third, the spatial distribution regularities of bar sandbody of the 3rd Member of Shahejie Formation and special rock units of the 1st Member of Shahejie Formation were determined and the optimal litho-traps existing in different sequences in the west slope area of Qinan were delineated by various means such as drilling, logging, geological survey, oil test, integrating forward modeling(GMAPLUS), seismic inversion(JASON), classification(Stratimagic), Spec Decomp (LandMark), attribute analysis and optimization (MDI), true 3D interpretation, 3D visualization (GeoProbe) and pattern recognition. Finally, several pre-exploratory wells were arranged in the west slope area according to the results of comprehensive reservoir description in Qinan, and all of them later produced high-yield oil and gas. The series of detailed description technologies for subtle hydrocarbon reservoir produced in this study may provide a good example for other similar hydrocarbon reservoir exploration.

The compound lithologic-structural oil reservoirs are located in Yaoyingtai regional uplift belt of Northeast China.Lithologically,there are mainly massive sandstones and fine-grained sandstones.The porosity and permeability of the reservoirs are generally quite low.The reservoirs consist of strata characterized by oil-water coexistence.The oil-water reservoirs of low porosity and permeability can hardly be discovered in geological exploration and borehole logging.Nevertheless,borehole geochemical exploration can reveal the features of oil-water coexistent strata.The authors combined the practice with research and application,and improved the recognition capacity steadily.As a result,a new borehole logging method has been established for recognizing oil-water coexistent reservoirs with low porosity and permeability.

The Huangchengshan silver deposit occurs in pyroclastic rock of Huangchengshan Formation and its basement.An integrated study of characteristics of ore geology,trace elements,isotopes and fluid inclusions shows that the ore-forming materials of the ore deposit were mainly indirectly derived from the pyroclastic rock of Huangchengshan Formation formed by volcanic eruption,and that the metallogenic media were dominated by meteoric water.Therefore,the deposit is of the shallow-seated volcanic hydrothermal type.It is held that silver mainly migrated in the form of [Ag(S₂O₃)₂]^3- complex under the shallow alkaline environment,and that geothermal fluid and its circulation and alteration action led to the formation of a series of mineral resources such as silver deposits and bentonite deposits.A metallogenic model of the ore deposits has been set up in this paper.

Exemplified by the Zhangxian salt district, this paper points out the advantages of applying the logging method to locating the rock and mineral bed. According to the electric character and radioactivity of the strata as well as their relationship, the binary regression method was used to obtain the theoretical equation for the salt mine district. The result of applying the empirical equation to salt mine grade interpretation is also given. Tests show that the application of the regression method to qualitative and quantitative interpretation is feasible. For the rock salt bed which can meet the related conditions, the utilization of this method can yield fairly ideal geological result, which has practical guiding significance in salt field evaluation.

Using inverse rotational projection, this paper has constructed 2-D continuous potential mother wavelets from 1-D continuous potential mother wavelets. At the same time, the widely-used mother wavelets for vector analysis and for tensor analysis are given. 2-D continuous potential wavelet transforms were conducted on synthetic models. SI (Euler Structure Index) for gravity sources was obtained by estimating the scale exponent, so that gravity sources could be identified. Gravity sources were quickly and successfully inversed by means of continuous potential wavelet transforms. This approach is useful in fast automation processing, inversion and interpretation of magnetic and gravity fields.

We can quickly and properly acquire the traveltime and ray path of first-break through forward calculation on the near-surface model by using linear traveltime interpolation ray tracing. As the first-breaks calculated by this method not only contain refraction but also other parameters, the problem of shielding layer in shallow refraction exploration caused by a low velocity can be satisfactorily solved. Moreover, based on gridding division and linear interpolation, this method can trace first-breaks in any complex media and can make the traced ray path approach the real condition, thus avoiding the direct connection of web nodes to form ray paths which causes a bigger traveltime value due to the serious bending of the ray path. Several other methods are compared with the LTI method in this paper, and the result shows that the LTI method is more precise and stable than other methods in calculating traveltime and ray path of first-breaks. It is thus concluded that LTI is an effective ray tracing method.

The central-loop device is an important surveying means for transient electromagneticmethod. It is necessary to make a rapid interpretation and improve the interpretation level. The electromagnetic field stimulated by the central-loop-source in the late period is similar to the plane-electromagnetic-wave. Through the time-frequency conversion, the TEM data are transformed to the plane-wave field data, thus constructing the system of M×N order underdetermined equations related to the reflection function. The authors have designed a computer programme to solve the reflected function sequence q_m with the method of Linear programming, and the error between the inversion result of a host of models and the theoretical value is very small, which indicates this method is feasible and the calculation result is correct. The electromagnetic response time-section is drawn with the parameter q_m, which realizes the explanation of the TEM rapid imaging. The imaging section clearly reflects the geoelectric characteristics of the section. The processing results of the field data demonstrate that this method is useful and practical.

In frequency domain electric exploration,the authors propose the utilization of the GPS OEM so as to improve the accuracy of signal phase estimation. 1 pps can be used as a time reference. The time synchronization of the frequency domain electric transmitter and receiver can thus be realized. This paper describes the framework, characteristics and principles of GPS in time synchronization. The frequency domain electric transmitter and receiver synchronization electrocircuit has been designed. It is concluded that the GPS time synchronization is feasible in this instrument.

Based on a brief analysis of the response of different settings in FAEM and a detailed description of the Occam algorithm, the authors successfully applied the Occam method to the processing of frequency-domain AEM data. As the algorithm is concerned not only with the rms misfit, but also with the smoothness of the model, it can steadily converge with wide initial values. The method was used in some theoretical models and FAEM field data, and the result is satisfactory and helpful to the interpretation of FAEM data.

A new data transmission system used for the ENVI MAG magnetometer has been developed.The system adopts VC++ computer language and can be run under the condition of Windows, like Win95/98/Me/2000/XP.It can be used to dump every kind of data measured with ENVI MAG magnetometer and stored in its memory. It wins advantages over the prior Bindump.exe software offered by the manufacturer which must be run under the DOS condition. The system the authors developed has the merits of rapidness, accuracy and easy operation. It can also directly dump the data coded decimal without transforming from binary to decimal with the Xfenvi.exe software offered by the manufacturer.

The method determines the incidence angle for every ray through scanning,and hence has very large computation work and needs to provide a relative precise preliminary geologic model.This paper introduces a kind of travel time inversion method based on polynomial.First,the depth and slowness can be expressed by Chebyshev polynomial.Then the structure and velocity variation of the complex construction can be acquired through iteration.Compared with the grid velocity inversion,this method has less unknown numbers,and does not need to provide a precise preliminary geological model.Model calculations show that the result achieved is close to the actual geologic model.

This paper has put forward the idea of utilizing Surfer to draw the initial data profile-plan. The programme compiled can realize the construction of Bln file. The profile-plans for regular net and irregular net have been constructed, and the results are satisfactory.

This paper describes the application of kriging to GPS data interpolation and the modelling of the variogram, and deals with some problems which deserve more attention in performing interpolation programming. Based on quite a few tests with real data, it is concluded that the application has a good result.

This paper describes the principle of the Ground Probing Radar technique (GPR), the hardware integration of GPR and GPS, and the measurement condition at the top of Mount Qomolangma. The elevation of Mount Qomolangma was measured again in 2005, and the ground probing technique was used for the first time to determine the precise thickness of the niveal bed. The processing and analysis of data reveal that the thickness of the niveal bed is 3.50 m at the surveyor's beacon of Mount Qomolangma.

With practical examples, crosshole sonic logging is employed in this paper to inspect the integrity of the cast-in-place pile (model pile) and to determine the degree of defectiveness. This method is proved to be very effective.

The crosshole seismic CT is a high-resolution response method for geological exploration. This paper describes the theory and field techniques of crosshole seismic CT, and presents an example to illustrate the application of the crosshole seismic CT to the detection of fissures in the foundation of a bridge. The means for obtaining good seismic data based on the authors' experience are given in this paper. Only by performing joint inversion of crosshole seismic data and geological data can good interpretation result be achieved.