It is hoped that this paper will be of some help to the discussion on geo--physical field, infrastructure and metallogenic specialization of granitoids in southeastern China and their connection with endogenic mineralizations.The crust and upper mantle model established by means of deep seismc sounding and gravity anomalies serves as the basis for division of crustal types and metallogenic prognosis, and the Moho depth and the crustal nonniformityseem to be the major criteria for division of regional metallogenic belts. The simulation and interpretation of regional gravity anomalies confirm the existen ce of relationship between W-Sn metallizations and Moho depression and low density zone in lithosphere as well as the relationship between Cu-Fe, Pb-Zn metallogenic belt and Moho uplift and steep slope zone.Due attention is also paid to the relationship of metallogenic provinces to local gravity and magnetic anomalies, chemical composition of intrusive bodies and deep faults in various directions. The metallogenic specialization of the gra nitoids is determined according to magnetism of rocks and petrochemical para meters.With the help of gravity simulation, the three dimensional shape and in terior structure of the granitoids at depth are determined, and this contributes to ore prospecting at depth and the research on ore potentiality of intrusives.The data obtained in southeastern China demonstrate the effectiveness and prospects of applying the gravity and magnetic field to the study of crustal structure, magmatic rocks and ore prognosis.

The detection of watersource channel proves to be of primary importance in water control and preventing floods in mines. The present paper suggests the application of such comprehensive underground geophysical techniques as drill hole radiowave penetration decay coefficient method and drill-hole high-pre cision temperature maasurement to the search for watersource channel. The tests conducted in two pits (one is flooded and the other not flooded) are given as examples, with a description of their effectiveness and economic benefits.

Arapid radon survey method for detecting blind orebodies, the ²¹⁸Po me thod, is presented in this paper. The working principle, characteristics and ore-searching effects of this method are described in brief, and the possibility of using²¹⁸Po method in search for blind orebody is discussed. In the end, the interpretation methods for the result of ²¹⁸Po survey is emphatically illustra ted. It is obvious that the ²¹⁸Po survey technique can be used not only to look for blind orebodies, but to predict quantitatively buried depths and sizes of blind orebodies.

Random, errors are ubiquitous in measurements of gravity and magnetic data, mathematical transformation processing of various kinds as well as direct and inversed calculations. One of the factors causing the instability of gravity and magnetic inversed solutions seems to be the existence of stochastic disturbance which, during the downward continuation and the calculation of derivative of higher degree, frequently enlarges the errors to an excessive extent, thus distur bing seriously the useful anomalies and making them unrecognizable.With a. purpose of looking into the influence of random errors on gravity and magnetic transformation, the author has made a deep investigation into the propagation of random errors in frequency domain.

This paper presents a new method for in-situ CO₂ accumulative determina tion, whose operating principle is that, after the reaction of CO₂ to blue alumina adsorbed with thymol phenolphthalein, the activated alumina changes from blue to white in colour. The CO₂-determining tube produced on this principle is buried in the loose layer about 50cm in thickness for 24 hours, then the CO₂ content of soil gas is determined according to the length of discoloured portion of the tube. This method was experimentally used in two areas, which yielded distinct anomalies over the known fault zones.

Soil mercury vapour survey is being increasingly carried out in China, and hundreds of atomic absorption mercury vapourmeters have so far been used for this purpose. The high price of gold-filament mercury-catching tube has hin dered seriously the substantial application of this method in production. This paper proposes to use a mercury-catching tube based on physical adsorption by active carbon instead of on routine chemical adsorption by amalgam. It has remarkably higher capacity for adsorption and deadsorption of mercury and can be used repeatedly so as to cut down the cost drastically. This enables any unit equipped with single wavelength atomic adsorption mercury vapourmeter to obtain enough mercury-catching tubes to perform soil mercury vapour sur vey on a large scale.The present paper deals with the optimum operating condition and work ing method for adsorption and deadsorption of mercury by mercury-catching tube, as well as the cause and measures for elimination of interference. In add ition, discussion is given concerning the theoretical existence of interfering gases in soil gas components.Two sorts of mercury-catching tubes recommended in this paper were tested and compared in several deposits, and their experimental application was un dertaken in a gold prospect in Zhejiang. The results show that the active car bon mercury-catching tube and the gold filament mercury-catching tube yield the same geological effect.

Trona deposit is one of the key mineral resources in China. The logging survey conducted over trona deposits in Anpeng area, Biyang depression by me ans of the 3600 digital logging system is described in this paper. After compu ter processing, the logging data obtained, besides giving back nine logging cur ves, can yield such parameters as contents of argillaceous substances, secondary porosity, apparent grain density, water-bearing saturation, waterlayer analytical parameters and porosity of trona bed, and rock and mineral compositions. Facts show the effectiveness of the logging method in prospecting for nonmetallic re sources such as saline deposits and trona deposits.

The appraisal of geophysical prospecting anomalies has previously been car ried out on the qualitative basis. In accordance with the characteristics of a skarn type magnetite deposit, this paper presents a quantitative comprehensive appraisal model for magnetic anomalies in the ore district mbiguous compre hensive appraisal model of subordinate function method, and also puts forward a new parameter Are certainty μ=C·B/T (where Cstands for matrix of coeffi cients, and B'Tfor the transposition of the comprehensive appraisal subordinate degree matrix B') as the criterion for final appraisal. Tests show that the accu racy of this appraisal model reaches 84%.