The 21th International Geochemical Exploration Symposium (21th IGES) was held in Dublin, Ireland from August 28 to September 3, 2003. Over 200 delegates from 27 countries attended the meeting. Fifty-eight papers were orally presented and fifty papers posted at the meeting. In addition to the scientific program, the Annual General Meeting of the AEG (Association of Exploration Geochemists) passed a resolution for the name change from AEG to AAG (Association of Applied Geochemists). While conventional geochemical exploration techniques such as soil and stream sediment surveys have been playing an important role in mineral exploration, lithogeochemistry and hydrogeochemistry remain interesting fields for geochemists. Much attention has been paid to the deep-penetrating technique and its formation mechanism in overburden, which represents the future trend of exploration geochemistry in the world. Indicator minerals, isotopes and biogeochemical methods are being studied for specific mineral deposits in special landscapes. ICP/MS has become conventional procedures for the analysis of elements and isotopes in geochemical samples. Although the number of papers on environmental geochemistry was increased, most of them were related to the environmental geochemistry of mines or mineral deposits. Thus, to get fully involved in the environmental field, we geochemists still have a long way to go.

Based on an analysis of structural characteristics of soil vertical profile, soil acidity-alkalinity and regularity of element distribution in thick overburden areas around the Poyang Lake, this paper has tentatively discussed characteristics of element associations and the position of "turning point of element content stability" towards the depth, and revealed geochemical characteristics of regional soil vertical profile and their environmental significance. According to statistical principle in combination with geochemical characteristics of regional soil vertical profile and conditions for large-scale production work, it is pointed out that the rational sampling depth of regional soil No. Ⅰ environment is -150～-180 cm.

Based on the study of the difference between aqua regia solution and HF-HClO₄-HNO₃-HCl solution and the distribution of elements in flood plain sediments A, B and active stream sediments, the authors hold that flood plain sediments A can be used as the effective sampling media in the ultra-low density deep penetration geochemical survey in the forest-swamp area of central Heilongjiang Province.

The utilization of new regional geochemical exploration methods in forest-swamp areas has widened the application of regional geochemical data and enabled these data to be used in basic geological survey. Based on regional geochemical surveying results of Shalanzhan sheet, the authors deal with in this paper the application of regional geochemical data to basic geological survey in the light of element associations, surface enrichment coefficients of elements, element content ranges and petrogeochemical data.

Obvious differences exist in the complexity of Pm waves obtained by deep seismic sounding (DSS) in different tectonic units. These differences are closely related to deep structural features. In this paper, a method is proposed for computing the complexity of seismic waves on the basis of its transient features and duration. For an ancient stable block, the Moho complexity coefficient is small, which reflects the feature of first order discontinuous interface. In contrast, for a strongly active block, the Moho complexity coefficient is large, which reflects the feature of crust-mantle transitional zone. Data processing was carried out with respect to a DSS profile which passes through the northeastern edge of Qinghai-Xizang Plateau. The result was interpreted dynamically.

High resolution borehole micro resistivity image logs (FMI) were used to investigate the origin of fracture structures, with Tarim basin in northwest China as an example. The result demonstrates that structural fractures and non-structural fractures (such as weathered fractures and fractures related to collapse of paleo-caves), extensional fractures and shear fractures, and the filling and solution characteristics of fractures can be differentiated with the help of borehole electric images combined with core calibration and interpretation of traditional well log curves. In addition, the attitudes of conjunctive fractures deduced from the borehole images provide important information for the direction of paleo-structural stress field.

Exemplified by the application of controlled source audio-frequency magnetotelluric sounding, this paper discusses the deep and periphery prospecting work with the resistivity sounding technique in the Bajiazi lead and zinc mine of Liaoning Province.

Lying at the core part of Qinling orogenic belt, the Weishancheng Au-Ag polymetallic ore belt is a complex tectonic belt produced by repeated convergence, piecing together and welding of several strata and terrains which were formed in different tectonic settings and had their respective formation characteristics as well as independent deformation, metamorphic and tectonic evolutionary sequences. This paper has studied the ore-forming process of this ore belt and magmatic rocks, major vein rocks, wall rock alterations, trace elements and geochemical characteristics of various epochs, probed into the regularity of element enrichment and variation, and established geological-geochemical ore-prospecting criteria.

Ore-bearing and barren rocks and soils were sampled in granite type uranium deposits, and their glowing curves and intensities were measured. A comparative analysis of the data indicates that the differences of glowing characteristics between ore-bearing rocks and soils and barren ones are obvious, and the soil TL survey can be used to find granite type uranium deposits.

Using such isotopic means as hydrocarbon acidolysis, top air measurement, adsorption filament and carbon methane, the authors made integrated oil and gas geochemical exploration and established goechemical anomaly models for indices of these methods in this area. On the basis of summing up anomaly regularity of known oil and gas areas, the geochemical methods and index combinations were optimized and then applied to unknown areas, which led to the delineation of oil and gas target areas. The relationship between surface geochemical anomalies and characteristics of petroleum geology is also discussed, which is helpful to geological interpretation of geochemical anomalies.

Based on D. C. exploration data obtained in the principal inclined shaft of the Songlou coal mine and geological and hydrogeological conditions of the coal well, the author holds that the cause of water bursting in the principal inclined shaft should be underground karst water derived from Quaternary sandy gravel water-bearing horizon and deep horizons. Through electric exploration, the fissure-developed zone, water-rich area and water gushing position were located. After performing mud grouting water exclusion measures at these places, the production was resumed.

The natural source surface wave frequency-waves (NSSWF) method is a new geophysical method deriving surface wave signals from natural source. In recently years, based on the learning of foreign files and analysis of the fundamental characteristics of surface wave, the authors have successfully developed the field observation and collection system and data processing system. Through testing large quantities of known holes, the field observation technique of stochastic matrix has been set up alongside with the test of the above method.

This paper describes in brief the basic principle, technical advantage and applicable conditions of the refraction static correction technique in CGG processing system, and deals with the influence of some key factors including the refraction datum level upon the refraction static correction. Exemplified by the application of this technique in mountainous areas, deserts and gobi areas, the paper also analyzes the results of the refraction static correction.

The ground-penetrating technique has been widely used in highway structure inspection. According to the regularities of reflection and refraction of the surface electromagnetic wave that take place at the interface between media with different physical properties, the amplitude and traveltime information of the radar-measured signal was used to realize the rapid automatic interpretation of road layer thickness. The numerical simulation analysis and the measured data were utilized to test the interpretation technique, and the result proves the effectiveness of this technique.

In this paper, the theory of using triangular radar to detect the metallic target is discussed, and the wavelet packet transform and its algorithm are also described in detail. The method of applying wavelet packet transform to pick up characteristics of radar signals is recounted, and the in-door experimental detection results are given.

The relaxation principle of the atomic nucleus system magnetization is discussed in this paper. Relaxation of hydrogen macroscopic nuclear magnetization is analyzed, Bloch equation of nuclear magnetization is given, free induction decay in receiving coil is presented, and relaxation about components of the nuclear magnetization and free induction decay is computed. In addition, the relationship of nuclear magnetization and free induction decay to the longitudinal and transverse time constants is analyzed.

The depth data logged again from China Continental Scientific Drilling (CCSD) progressive CCSD-1 well after the completion of the first 0～2 000 m drilling plan are different from the data measured last time. Corrections must be made for the veracity of the logging data. In this paper, the logging data were pre-processed before the correction, and several methods were applied for analysis during the correction. The results of correction are satisfactory and fully meet the required precision. It is shown that the correction analysis is an effective method for correction. Nevertheless, the processing of the parts with obvious different logging curve shapes needs further investigation. The whole process is automatically done on computer, and the technique can obviously improve the data-processing efficiency.

With the neural network method, this paper used geochemical exploration and geoelectric as well as remote sensing data to evaluate hydrocarbon-bearing characteristics of Liandaowan area, with satisfactory result obtained. The trained result was further analyzed, and thus important factors were selected. The evaluation effects based on different types of factors were compared. The results are of guiding significance in factor optimization.

This paper has analyzed the difficulties in the exploration of the transitional zone in Kendong area, such as the unfavorable exciting and receiving conditions of the seismic wave and the development of the disturbing wave. The seismic wave excitation and receiving as well as measures for improving the detector are discussed, the improvement of the detector and the couple effect of the surface is studied, the parameters of air gun source and dynamite source are optimized, the detector fixation method is improved, and the real time fixed location monitoring of the detector is carried out. With the adoption of the above measures, the signal-to-noise ratio of the seismic data was raised, and the seismic data acquisition task was successfully completed.

According to anomaly characteristics and with the help of Mapgis software, the measuring points affected relatively insignificantly by the local anomaly in measured data were chosen through sieving, and the curve or curved surface represented by a n-order polynomial expression was used to approximate the regional anomaly contained in these measuring points. The coefficient of this polynomial expression was used to calculate the polynomial value of every measuring point in the whole surveyed area, and the value was used as the regional anomaly of the measuring point. On such a basis, the local anomaly can also be obtained.

Based on an analysis of the SVD method, the authors advance a filtering method based on singular value decomposition in f-x-y domain. The method is a true three demension. With this technique, it is not necessary to know the dip of the event when the random noise is eliminated. In addition, the amplitude of the event can be preserved. The results of data simulation show that, with its rapid operation time, this method is very effective.

In the course of processing geophysical well logging data or developing well logging interpretation software, it is important to know the format of well logging data file. In understanding the format of well logging data to be processed, much work can be done, such as reading data, transforming data format, processing data and plotting. On the basis of analyzing XTF file format of ECLIPS 5700 well logging system, a class of reading XTF format data was built with the object-oriented method based on the memory mapping file technique. This technique realizes fast reading of XTF format file with mass data and also provides the technical reference for format transformation and data processing of other well logging data formats.

As a newly developed exploration method, the transient Rayleigh wave method still has some defects. With practical examples, this paper has investigated and discussed the data-collecting technique in transient Rayleigh wave materials, and analyzed various factors affecting the transient Rayleigh wave exploration and the data-collecting technique that should be adopted. In this way, the purpose of improving the data collection quality of transient Rayleigh wave can be achieved.

This paper describes the result of a test in a more than 400 m deep well. Practice shows that, with the adoption of some measures, the PS wave of single drillhole layer-testing method can break through the limit of one hundred meters. This technique can therefore be used in more extensive application fields.

Based on a detailed analysis of several main factors in the ultrasonic testing of non-equal diameter drilling hole, this paper puts forward some relevant improving measures. From a large number of successful engineering examples, it is believed that the utilization of ultrasonic reflecting technique is an absolutely necessary means for ensuring the hole quality of the non-equal diameter drilling pile.