According to geophysical field characteristics, seismic sounding, magnetotelluric sounding and recent geological data, the boundary between Chinese platform and Da Hingganling-Mongolian Paleozoic geosynclinal folded belt lies along Xar Moron River- Wenduermiaobei-Baiyinyanzhongxingaobaobei-Baoyintubei-Qeh-Talin tectonic line, and from Talin eastward, the geosyncline-platform boundary stretches along the northern boundary of Tarim platform; from Xar Moron River eastward, the geosyncline-platform boundary pinches out on the southwestern edge of Songliao Precambrian landmass.

This paper discusses the fine velocity structure in the shallow crust on the basis of the wide-angle seismic data collected along the HQ-Eprofile. The velocity structure depicts the characteristics of formation and development of the South China fold belt. The shallow crust is composed evidently of four strata: sedimentary cover, sediments, Caledonian fold basement and Proterozoic crystalline basement. The velocity structure shows obvious differences laterally along the profile. To the northwest of Wuyi Mountain (near Ningdu), the low velocity depression is correlated to the Mesozoic and Cenozoic basins, with strong relief up to a maximum depth of 10 km at the bottom of the Variscan fold basement. As for the velocity structure to the southeast of Ningdu, the velocity near the surface becomes much higher, and the bottom of the Caledonian fold basement gets thinner, merely 3～5 km in depth. At the end of this paper, the author makes a tentative analysis of several basins according to the fine velocity structure in the shallow crust.

A comparison of the result from stream sediment survey with that from grid soil survey or chipping rock survey indicates that in the forest and swamp landscape of Da Hinggan Mountains, the tradition stream survey should be replaced by the new grid soil survey or chipping rock survey in the 1:50,000 follow-up for regional geochemical anomalies.

Based on a review of regional geochemical prospecting techniques adopted in more than twenty years' geochemical exploration work within the special langscape area of Gansu Province, this paper points out the problems that should be emphasized and the techniques that ought to be popularized in future work.

The development of oil and gas geochemical exploration in the past forty odd years has been full of frustrations. We have persisted in introducing techniques from abroad, test and reformation, opening up new roads and bringing forth new ideas, and, as a result, gradually established and formed oil and gas exploration techniques with Chinese characteristics. The Chinese characterization has been realized in such aspects as the sieving of geochemical methods and indices, the study of application conditions, the improvement of analytical technology, and the data processing, interpretation and evaluation. The further introduction of new techniques and methods from abroad, the utilization of the experience of other countries for reference, and the bringing forth new ideas in practice are absolutely necessary to sustainable development of oil and gas exploration.

In Mesozoic, Longbaoshan intermediate-alkaline complex was formed as a result of two stages of magmatic intrusion. As shown by statistical analysis of REEin the complex, the total content of w ΣREEis nearly 2.5 times as high as the Clarke value, the ratio of w LREE/w HREEis nearly 9 times that of the crust, and light REEis greatly enriched, whereas Eu and Ce are slightly depleted. The REEdistribution patterns of various stages of intrusives and auriferous quartz veins are basically similar to each other, all dipping steeply towards the right. Nevertheless, ΣREEand LREEare richer in auriferous quartz veins than in magmatite. Combined with the geological and geochemical characteristics, the authors conclude that magma and metallogenetic materials of the complex were derived mainly from the same magma chamber in the upper mantle, and assimilated and mixed with the wall rocks during the intrusion of magma into the crust.

Based on the storage properties of deep-seated karstic water in south Ningxia, this paper analyses the test results of the combination of four geophysical techniques in exploring deep-seated karstic water of south Ningxia, and describes the drilling effects. On such a basis, an optimal exploration model for the exploration of this kind of groundwater at present is put forward.

The seismic wave impedance inversion technique is becoming an increasingly important tool in carrying out reservoir prediction for oil exploration and development. There exist both turbidite sand and thick-bedded halite in S^2-3 formation of Liutun sag. The lithofacies vary greatly in transverse direction. The application of the Strata inversion technique in this area is discussed according to the data processing order, which mainly includes well logging data correction, wavelet extraction, correlation of the synthetic records with the seismic profile, establishment of the initial model, and the constraint inversion. Ideal results are achieved showing the gradual modification from the deep turbidite fan to the salt lake face. The contour map of the sand body in each system tract is made, so the spatial distribution of the reservoir is characterized.

This paper describes in brief the lithologic profiles and the geophysical logging curves of the low resistivity oil and gas layers in Tabei area, analyzes the origin of the low resistivity oil and gas reservoirs in that area, and deals emphatically with the principle of applying the neural network to recognizing oil and gas layers, oil-water layers, water layers and dry layers. The recognition of low resistivity oil (gas) layers and water layers is consistent with the real conditions, thus obviously improving the interpretation precision of logging data.

This paper processed the simple fractal data with pyramidal algorithm of wavelet analysis and, in combination with the "random resonance" theory, analyzed and approached noise and error in high-precision micro-magnetic anomaly. According to residual magnetic anomaly detected by tendency analysis, the authors suggest controlling normal random Brown motion of non-integer rank calculus with "shift with the window" least squares technique, and provide essential guidance for effective recognition of high-precision micro-magnetic anomaly.

Based on the method for evaluating oil and gas geochemical anomaly and the principle for formulating its parameters,this paper points out that the formulated parameters should not only have definite geological and geochemical implications but also accord with a certain mathematical principle as well as the optimization criterion.On such a basis, the paper deals with the attributes of anomaly and background as well as methods for their determination,describes roughly the criteria for judging oil and gas anomalies,emphasizes the importance of the correlation between composite anomalies and variables as well as the extraction of associated information.

Due to the difference of the physical and chemical properties between the normal paraffin and the isoalkane which have the same molecular weight,they are affected by the physical and chemical property of soil substrate and other external environmental factors and are hence likely to have some differentiation effects during migration,rendering their distribution in space characterized by some signature and regularity.Isomerization rate indicators φ_iC4 /φ_nC4 and φ_iC5 /φ_nC5 can expose to some extent the characteristics and regularity.With the isomerization rate indicators φ_iC4 /φ_nC4 and φ_iC5 /φ_nC5 ,we can determine organic maturity,path and direction of light hydrocarbon migration and light hydrocarbon generating environment,and study biochemical degradation of light hydrocarbon.

This paper deals with characteristics of the natural electric field "8"-shaped maps under different hydrogeological conditions, which are of guiding significance in the evaluation of the environment caused by the leakage of waterlines.

In this paper, the effects of using conventional KLtransform and dip scanning stack KLtransform to remove coherent noises in seismic record are discussed, with their scopes of application and limitations pointed out. Based on these two methods, the authors suggest a new technique for removing coherent noises, which is called space-time variety and dip angle KLtransform. With this technique, we can not only remove the strong coherent noises effectively but also maintain the continuity of effective events. The validity of this technique has been proved by applying it to the synthetic data and the real data.

Based on an analysis of the cause and characteristics of man-made interference to the observation of magnetic diurnal variation in aeromagnetic survey and making use of computer technique, the authors designed an editing software for suppressing man-made interference in visualized magnetic diurnal variation on the basis of suitable mathematical means, which can raise the correction precision of magnetic diurnal variation and solve practical problems in production.

The author selected and edited some data concerning the application of the ground-penetration radar to the detection of underground pipelines. On the basis of detailed experiments, the effects of such factors as the thickness, material quality, filling substances and defects of the pipelines as well as the frequency and noise of the antenna upon the radar images are analyzed, which will be of some help to further application of the ground-penetrating radar to urban underground pipeline detection.

By the application of 2D inversion, the accuracy of high density resistivity method has been greatly improved. With some examples of applying the inversion method to engineering survey, this paper deals with the characteristics of the high density resistivity method and the superiority of the 2D inversion.

With practical examples, this paper deals with the basic principle and technique of the Rayleigh surface wave exploration, the technology for its application to railways, the data acquisition, processing and interpretation, and the calculation method for converting the velocity of the Rayleigh surface wave to the bearing capacity. The reliability of applying this technique to railways is also pointed out.

The relative displacement of the pile head which occurs when the pile soil system is impacted by the free-fall hammer is the dynamic response of the dynamic rigidity of the pile soil system to the acting load. During the low strain dynamic test of the foundation pile, the adoption of the velocity sensor to the direct measurement of the relative displacement of the pile head is helpful to reducing the improper dependence upon the measured intrinsic frequency valuesof the pile soil system in calculating vertical bearing capacity of the single pile, and is hence conducive to raising the accuracy of the calculated vertical bearing capacity of the single pile.