Achievements and shortcomings of geochemlcal exploration in China inthe 1980s are reviewed with aim to better strategic planning of geochemicalexploration research and development works toward the Year 2000.China's national geochemical mapping project （Regional Geochemistry-Reconnaissance RM Project） has been very successful in the 1980s. About4 million km² of China's territory have been covered by this project. Morethan 600 new mineral occurrences and 158 new economic mineral deposits havebeen discovered. Optimum sampling methods for arid, semi-arid, igh mou-ntains, karst and loess-covered terains have been developed. Effective multi-element analytical systems and data quality monitoring procedure have beenworked out. All these make China ahead of the world in systematic geochemi-cal mapping. The main shortcoming is that the research imputs have becomelesser and the project has changed more and more into purely routine opera-tions in the later half of 1980s.That geochemical mapping will be one of the most important researchfrontiers in geosciences and exploration geochemistry has been acknowledgedby many prominent earth scientists of the world. The preponderance intechnics developed and information accumulated in this field of study isproviding exciting opportunities for Chinese exploration geochemists in the1990s. Some important and promising research topics are briefly suggested.

This paper describes for the first time analytical results of Au and Ag inthe Rehai geothermal field of Yunnan Province and in the Yangbajing geother-mal field of Tibet. It is found that soil and rock over these geothermal fieldscontain fairly hish Au and Ag, associated with anomalies of such elementsas Ag, Ab, Sb, Bi, Pb and Tl, indicating that gold mineralization might existin the geothermal fields which, therefore, are favorable places for gold prospe-cting.

Based on an investigation into magmatism of roof sandstone of the Pi-ngzhuangxi opencut coal mine in Inner Mongolia. this paper points out thatthe Upper Jurassic grey sandstone of the roof of the coal mine is weakly ma-gnetic under natural conditions. The natural remanence and the magnetic su-sceptibility are n × 10^-3A/m and 10^-4 (SI) in order of magnitude respectively.After high-temperature heat treatmellt (>600℃), however, magnetism incre-ases rapidly: remanent magnetism and magnetic susceptibility increase by fiveand four orders of magnitude respectively. It is found through rock and oreanalysis of various means that the cement of the sandstone is weakly magne-tic iron carbonate (FeCO₃), which. after high-temperature treatment, turns intostrongly magnetic magnetite(Fe₃O₄). Such change seems to be the major factorcausing the appearance of magnetic anomalies over many Jurassic coal fieldsin North China. The change in magnetism of pyrite through heat treatment isalso described. Finally, using magnetism of rocks that was determined, we havedesigned quite a few theoretical models and made direct calculation for valuesof magnetic anomalies. The results show that it is quite possible to distinguishself-combustion districts from non-self-combustion districts by means of high-precision magnetic exploration.

A study of the relationship between physical properties of rocks and pri-mary anomalies was conducted in the Xianghualing tin, lead and zinc polyme-tallic ore district in Hunan Province, and physical and chemical analysis wasmade for 153 samples from the ore-related Laiziling rock body and Jianfenglingrock body as well as their wall rocks. As a result, four physical parameters(density σ, magnetic susceptibility k, residual magnetization Jr and a specificratio Q) and contents of seven metallogenic elements (Pb, Zn, W, Sn, Ag, Moand Be) have been obtained. Studies reveal the existence of obvious correlationbetween physical parameters and element contents, and their anomalies arein good conformity. Such correlation can therefore be used to perform geologi-cal exploration and metallogenic prognosis.

The exploration method of transient Rayleigh wave is a new seismic me-thod for quick and economical determination of Rayleigh wave velocity in rockand soil layers. The actual shear wave velosity is calculated using Rayleighwave velosity. In this paper, the principle and field testing technique of thisexploration method is described. Several case studies are cited to illustrateits utility. Finally, the advantages of this method are discussed.

The automatic pick of the first arrivl time has been one of the basic and important problems in seismic exploration. Based on some simple assumptions, previous researchers have already put forward several computerized algorithms for automatic pick of first arrival time; neverthless, the pick precision is always affected by noise and waveform variation. This paper advances a technique for picking the first arrival time, composed jointly of an improved dip angle scanning correlation algorithm and an improved energy ratio method. After conductig noise suppression for seismic channel by means of scanning correlation algorithm, this technique employs the energy ratio method to determine rough first arrival time of the possibly existing effective wave, then uses the dip angle scanning correlation algorithm to verify the existence of effective wave, uses the peak value method and the inflection-point correction method to evaluate the precise first arrival time and, finally, uses empirical criteria for hand pick to examine the reliability of the first arrival and correct the interchange time.The algorithm put forward in this paper has been realized on Z-181 microcomputer, with fairly good results obtained in the automatized interpretation of refracted wave exploration for protection of cultural relics in Lian-yungang City, Jiangsu Province.

Based on piezoelectric effects of rocks and minerals, this paper has caclu-lated piezoelectric fields produced by piezoelectric bodies in the form of slen-der rod and thin plate under the action of elastic wave as well as theirdistribution regularity, and derived a theoretical calculation formula for thethin-plate piezoelectric body. These outcomes are of some significance in thestudy of spatial distribution regulariry of piezoelectric fie1ds of rocks andores and the interpretation of piezoelectric data.

This paper deals mainly with some problems in vertical electrical sound-ing under complex conditions, especially some interpretation methods for car-rying out vertical electrical sounding in "finite horizontal layered uniformmedia", e. g. in "finite electrical bodies" such as metallic deposits and karstareas. Anomalous characteristics of some "finite electrical bodies in the conto-ur diagram of ρs section as well as field experimentS are described. A discu-ssion is also given on the compilation method for the contour diagram of ρs.section.