In order to adapt itself to the increasingly difficult situation in a newround of ore prospecting, especially to meet the requirements for detecting oredeposits which are located at depth or difficult to recognize, the geophysicaland geochemical prospecting should be armed with some new strategic thou-ght. In determining a reconnaissance target, one should exactly know its chara-cteristics. Therefore, a geological-geophysical-geocheical model of target oughtto be established to guide the whole reconnaissance and prospecting work.

This paper gives a summarization and review on geochemical gold prospe-cting work in1978-1987 organized by Ministry of Geology and Mineral Resour-ces. Using geochemical prospecting method the Ministry. has discovered in thepast ten years 272 gold occurrences,. of which 62 are proved to be industrialgold deposits. The main experience gained is as follows: (1)Every effort shouldbe made to use trace gold as the indicator element in gold prospecting; (2)in geochemical gold prospecting work, one should stick to the principle of "carrying out the work on a regional scale and making breakthrouth at mostfavorable points"; (3) the choice of areas for geochemical gold recounaissanceshould be based on gold anomalies detected in1:200,000 regional geochemicalprospecting;(4) the on-the-spot trace gold analysis method ought to beadopted in follow-up for gold anomalies. Regarding the future developmenttrend of geochemical gold prospecting in China, the authors puts forward thefollowing views: (1) The compilation and study of regional geochemical mapsfor gold and related elements are expected to be accelerated; (2) the analy-tical method and technique for trace gold will be further developed, and it issuggested that an on-the-spot analytical method and technique for simultane-ous determination of Au, Ag and As should be worked out; (3) the study ofrepresentativeness in geochemical gold sampling wil1 be put on the agenda;(4) the study and follow-up for gold anomalies will be extensively carriedout; and (5) important advances will be made in the research of geocbemicalgold prospecting in thick overburden areas.

This paper gives a comprehensive description of the application situationand recent advance of geophysical prospecting in exploration of groundwaterresources, engineering geoloic survey and civil construction in China. It dealswith the main methods used and illustrates with examples the practical app-lication of geophysical prospecting in this field.

Through the investigation of variations in oxygen and carbon isotopes sur-rounding orebodies in Shuiximiao deposit of Limu area, Wuzhishan, Jiuban de-posit of Jiahui area and Shuiyanba ore district of Pinggui area, the authors havediscovered that the isotopie determinations can be used to draw contour linesand predict as well as delineate blind orebodies.

Among the sediments of continental facies in China,the clastic sedimenta-ry facies related to oil-gas fields include pluvial. fluvial, lacustrine, delta andturbidity current facies.The sedimentary facies is an integrated manifestation of sedimentary envi-ronment and sedimentary characteristics.The logging response had close rela-tionship with sedimentary environment and characteristics of sediments,and dif-ferent sedimentary facies show different logging features; therefore, loggingfeatures seem to be an important means for recognition of sedimentary facies.This paper deals with logging features of sedimentary facies and givessome examples illustrating the recognition of sedimentary facies of clastic rocksby means of logging technique.

Based on the gravity model of variable density combinational body, theauthors have developed the method and program for automatic fitting of gra-vity curves.The advantage of this method lies in the fact that it utilizes theknown geologic and geophysical data to the maximum extent, and thus canovercome the interference by man in the process of man-machine interaction;in addition, as a result of progressive modification of the thickness,width anddensity for various layer sections during the curve fitting, the computationand fitting are carried out as a whole, so that the calculation precision canbe greatly raised. No operator is required in the course of computation, andhence the purpose of saving time can be attained.

By utilizing data from the absolute geomagnetic charts (197l, 1980) com-piled by Institute of Geophysics,Academia Sinica, the principle of sphericalharmonic analysis was adopted to extract regional field, and the principle offrequency spherical analysis was employed to evaluate the depth of Curie sur-fuce. In this way, data-processing was made for geomagnetic fields in the250, 000 km² sharply curved area of the Yarlung Zangbo River. In combinationwith the geologic, geothermal and seismic data of this area, the variations ingeomagntic fields and magnetic basement were analysed comprehensively, andthe locations, strikes and dips of the tectonic lines of deep faults in this areadeduced. All these results provide reference information for the knowledge ofgeoiogic conditions at depth of this area.

The electromagnetic method seems more effective and easy to handle thanother electric survey techniques in detecting such underground conductors asmetallic pipes and cables. The method of using nonreference-line imagin-ary component instrument (DDW-1) and adopting orthogonal circuit device toobserve imaginary components of magnetic field is especially suitable for dete-cting metallic conductors in cities (even in urban districts). This is becausethe system only has a narrow band receiver and is not connected to ground,and the observations have little to do with the transceiving distance. General-ly speaking, the induced current caused by metallic pipes and cables in theelectromagnetic field can be approximately regarded as line current, so the in-terpretation of the data is rather simple. The present paper gives some out-comes obtained in urban and suburban areas of Beijing.