The gravity field of South China is obviously different from that of Nor-th China in that the former is characterized by extremely intense negativeanomalies caused by reduction of the density of the lithosphere as a result ofgranitization of the crust. In coastal areas, the Bouguer gravity anomalies showno correlation with the relief of the Moho, and the inhomogenity of densityof the crust and upper mantle seems to play a dominant role in the distribu-tion of the gravity field. The widespread granitoids in South China reflect aspecial crusta' structure of that region. The exposed areas of granites coincidequite intimately with gravity contours, which makes up a favourable prere-quisite for applying gravity data to the quantitative inference and interpre-tation of the shape of granite body at depth. In this paper, a discussion ismade concerning the application of gravity modelling to the study of the earthcrust, the structure of the upper mantle and the subsurface shape of granitesin South China, with a tentative investigation into the genesis of granite andits relations with mineral resources.

The existence of a certain amount of clay minerals, chiefly kaolin, in thesample will give rise to some systematic deviations in analyses of severalvolatile elements, and the bad effect on lead is especially serious. The presentpaper elucidates systematically the mechanism of its action and suggests add-ing"buffer layer"material into the electrode to eliminate this effect; the resultof this measure has already boen proved to be satisfactory.

Arapid colorimetric technique for determination of active iodine in soilsis recommended in this paper? this method, based on the reaction betweentetrabase and chloramine T, has the determination range of 0.01-1ug/25mland is characterized by simplicity and high efficiency with 50-60 determin-ations made per man-day.The possibility of using iodine as a pathfinder element in geothermalexploration has been investigated. With the mentioned colorimetrie methoda-bove, the authors have determined 193 surface soil samples along11 profilesover the Yangbajing geothermel field in Tibet, covering an area of 25 km2.From the data obtained, a map showing the distribution of extensive andintense iodine anomalies is drawn. The distribution of iodine anomalies coin-cides quite well with that of resistivity or soil mercury anomalies, and is inconformity with the underground geothermal reservoir. This implies thatIodine is likely to be an important pathfinder element in geothermal explora-tion.

This paper outlines the physical basis of flow rate logging, advances itsunique theorem, and also deals with tLe hydrogeological theory for obtaininghydrogeoJogical parameters of various aquifer beds in a drill hole by means ofprimary mixed withdrawal. Practical examples are given to illustrate thetechnical superiority and economic potentiality of flow rate logging.

Second order linear system has been adopted to describe the property ofthe simple-shaped polarized body in homogeneous electric field. The responseto the order-leap signal by this earth current cross section is a linear combin-ation of two exponential functions. StudiesreveaJthe following facts.- two timeconstants of the system are only related to geophysical parameters and areinvariable with respect-to the whole observation profile? the coefficients ofthe two exponential functions are connected not only with geophysical para-meters but also with geometric factors; the value and sign of the two coeffi-cients are variable at different survey points in the profile. Consequently,eight different types of discharge curves might exist. The effect of continuouscharging interval on discharge curve has also been examined. Theoretical calcu-lations may well be used to explain field suiveyed data and model test resultsprovided by such previous workers as J. Bertin, J. loeb and Fu Liangkui andmay indicate some existing phenomena which remain undiscovered. The authorholds the opinion that the theoretical research method adopted in this papermight find application in more complicated circumstances.

Based on determinations of induced polarization properties for large quan-tities of rocks and ores as well as field data from volcanogenic ore deposits incoastal areas of southeast China, this paper dwells upon tnacroscopically andmicroscopically the characteristics of induced polarization of rocks and oresfrom volcanogenic ore deposits and the features of anomalies caused by thisinduced polarization. Aclassification of these anomalies has also been made inconsideration of various types of volcanogenic ore deposits, and each sort oftypical induced polarization anomaly has been illustrated with examples.

This paper proposes a method for determining the degree of the fittingpolynomial in Separation of gravity anomalies by means of trend analysis. Thesingle anomaly can be fitted by polynomial of different degrees with the leastsquares method, and the degree of the polynomial fitting this anomaly can beEstimation by "distortion poinfon the curve representing relationship betweenvariance of fitting degree and degree of the polynomial. The superimposedanonaly is firstly roughly divided by upward Continuation of different heights,and then the degrees of polynomial can be Estimation respectively. Tentativetheoretical calculation shows that this method not only can be applied satisf-actorily to the single anomaly caused by an individual geological body, but issuitable to some extent to the superimposed anomaly brought about by seve-ral geological bodies as well.

Based on the examination of the magnetic parameter Qvalue  ofores from quite a few magnetite deposits in Heilongjiang Province, the authorssummarize the variation range and frequency distribution of the Qvalue inore deposits of different geneses, and formulate a spatial distribution model ofQvalue in orebodies of various hydrothermal magnetite deposits. These argu-ments are supported by two practical examples.

Following a brief discussion on the deve'opment and evolution in the field ofnonmetallic mineral resources, this paper points out the necessity for streng-thening the research work and application of geophysical and geochemicalprospecting for these resources. Geophysical properties of such nonmetallicmineral resources as special types of nonmetals, raw materials for chemicalindustry, building materials and auxiliary metallurgical raw materials are dweltupon individually, and their integrated geophysical and geochemica) prospec-ting methods are also presented.