Along several plate suture zones discovered in Qinghai-Tibet plateau, there are ophiolite complexes dominated by basic and ultrabasic rocks, most of which can be discerned to some extent in 1:1000000 Airborne Magnetic Map of Central and Western Qinghai-Tibet Plateau. According to their distribution, the authors have divided these ophiolites roughly into three types for reference in the work of recognizing suture zones.

It is known from the 1:1000000 10′×15′ average isostatic gravity map that the northwestern Hunan area assumes gravity high, and the other vast areas are basically characterized by zero isostatic anomaly if the local gravity low corresponding to granite is eliminated. The authors consider the northwestern Hunan area to be the isostatic dislocation area in Hunan Province, and make an analysis of this problem from five aspects.

Using achievements gained by wave velocity test which contain abundant geophysical information, this paper deals with the sedimentary process and sedimentary environment of Pleistocene-Holocene sediments in the southern limb of the Yangtze delta.

In the Liutang ore-prospecting target area on the outskirts of the Hunan lead-zinc polymetallic orefield which has been investigated in great detail,the authors used integrated methods,such as high-precision magnetic survey,high-precision gravity survey,high-sensitivity soil and rock survey,and carbon-oxygen isotope determination, to conduct reconnaissance and detailed investigation.In the Liutang prognostic area which shows no mineralization and alteration at surface,the utilization of the"magnetic field sudden change area"and weak Pb,Zn,Ag,Sb and As anomalies as the main indicators led to the discovery of a concealed lead-zinc-silver deposit at the depth of greater than 400 m.It seems that the utilization of new methods and new techniques is the best means for extracting deep ore-prospecting information in the investigation and evaluation of mineral resources in ore prospect areas (belts).This paper has summed up the basic train of thought for ore prospecting and prediction,and illustrated the successfulness of using the "prediction-reconnaissance consistency" principle.

Based on geochemical technical tests conducted in the Yanzidong ore block,western Yunnan,the authors used the hydrochemical survey as the Grade 3 inspection method for high canyon target areas, and rearranged the methods for routine stream sediment survey and soil survey.These measures show satisfactory ore prospecting results and can greatly raise the working efficiency.

This paper has described the principle of the contact polarization curve method and the technique for measuring basic parameters, analyzed the influence of such factors as oxidation conditions of the ore deposits, arrangement of electrodes and structures of orebodies on the basis of studying some typical polarization curves, inferred several parameters such as independency of orebodies, reacted minerals, effective areas of reacted minerals, reserves of elements and grades of elements for some measured typical curves, and compared the inferences with the exploration results. It is held that the contact polarization curve method, being an exploration technique characterized jointly by immediacy, long distance and totality, is especially suitable for conductive sulfide ore deposits.

The combination of such means of data processing as electric sounding derivative calculation, change rate calculation for deviation zone of combined profiling ρ_s curve, multi-profiling cross correlation processing and IPdata processing has proved to be effective in raising anomaly resolution of the water-bearing structure and thus can play an important role in water exploration work in karst stone hills of northwestern Hunan.

Based on the different responses of compensated neutron log (CNL) in the gas reservoir before and after mud filtrate invasion, the authors designed the test of time-lapsed CNLin cased hole. The result indicates that time-lapsed CNLis effective in gas identification of a reservoir whose permeability is higher than (1～3)×10^-3μm². The test has provided a new method for the interpretation of the questionable, low resistivity or mud contaminated reservoir and for the restudy of old well data.

Measurements of U and Ra in100 soil samples collected from Gejiu area in Yunnan Province show that the Ra/Uequilibrium ratio is 0.65,implying that Uis richer than Ra.Some indications of regional disequilibrium have also been found.The spreading equilibrium ratio values indicate that disequilibrium may cause errors in Uchannel data obtained by ground gamma-ray surveying. Neverthelsss,these data can be improved to some extent by equilibrium ratio correction.

In this paper, the implementation and techniques of the Regional Geochemical Data Management and Information System (GeoMDIS2000) are dealt with on the basis of analyzing features of the regional geochemical data and applying GIStechnolgy and Object-Oriented Database. The managing model of regional geochemical spacial data collection, the visualizing data query with geographic and geological vector maps, and the conventional geochemical data processing and geochemical mapping technology are also described.

Starting from the calculation formula for transient electomagnetic response of vertical magnetic couple source at the surface of horizontal layered media and in accordance with the interchange principle, this paper worked out a very useful forward calculation formula for device of induced electromotive force measured by coil within the range of field angleθon both sides of the perpendicular bisector (with emission from couple pole source), and calculated transient electromagnetic response of couple pole source in horizontal layered media by using M. M. Goldman's mixed algorithm. The result proves the advantage of the mixed algorithm.

Resolution in crosshole seismic tomography has been studied in this paper by means of ray density, ray orthogonality and point-spread function. Numerical experiments indicate that the resolution is better in the vertical direction than in the horizontal, and the high velocity anomalous body is different from the low velocity anomalous body in resolution and shapes of tomography. For the high velocity anomalous body, the spatial resolution of the waveform velocity tomogram in horizontal is about 1/2 of the wavelength, and that in vertical about 3/10 of the wavelength. For the low velocity anomalous body, the spatial resolution of the waveform velocity tomogram in horizontal is about 2/5 of the wavelength, and that in vertical about 1/5 of the wavelength. The spatial resolution of the traveltime velocity tomogram in horizontal is about three tomographic elements width, and that in horizontal about two tomographic elements width. When the ratio between the borehole depth and well offset is equal to 2.0, the spatial resolution of the velocity tomogram is the best.

Based on the comparison and analysis of four major filtering methods designed and developed in China, this paper derived a new expression of the filtering technique. The author chose a representative filtering method, simulated the observational field on computer, and investigated the distortion of gravity and magnetic anomaly caused by filtering under the condition of complex interference. On such a basis, a feasible method is proposed concerning the inversion interpretation under such a distortion condition.

Based on an analysis of the seismic data of Tazhong desert, the authors put forward such techniques as residual static correction of separate migration consistency from the surface and multirange denoisization before stack. The practical seismic data processing has remarkably improved the signal-to-noise ratios of medium and deep layers. This paper has summed up a set of processing techniques of low signal-to-noise ratio suitable for desert areas.

The quality of large quantities of retaining wall made of mortar and stones should be examined rapidly. Based on the comparison of elastic wave velocity, Rayleigh surface wave and elastic wave frequency spectrum analysis, the author holds that the last technique has the merits of high resolution and simple operation. The tests made at several hundred points prove to be successful.

This paper describes the principle and method for testing pile bottom force-bearing layer and pile body force-bearing declivity, deals with results of standard component test and inclined model pile test under the condition of inclination, and also gives some practical examples of engineeing application.