According to an investigation into abundant data of rare earth elements V, Ce, La obtained during the 1:200, 000 regional stream sediment survey for Zhangla, Songpan and Plngwu sheet areas, this paper holds that these ele ments can play a peculiar role in classification of Au, W and some other ano malies, differentiation of mineralization anomalies of various magmatic rocks, and the study on strata and metallogenic characteristics of different tectonic areas as well as on regional geochemical characteiistics of elements, thus un doubtedly serving as good geochemical indicators. This understanding opens ip a new train of thought for the study of regional geochemical data.

According to the assessment and the checking and acceptance of some fifty 1:200, 000 regional geochemical prospecting map areas, it is considered that the comparatively low quality shown in a few map areas of MGMR is mainly attributed to the unclear quality requirements and loose management. Based on experience gained by MGMR, the authors have compiled "Quality Evaluation Criteria for Field Sampling, Sample Processing and Firsthand Data in 1:200, 000 Regional Geochemical Prospecting"and "Criteria for Marking Mul tielement Analytical Quality in 1:200, 000 Regional Geochemical Prospecting". Nearly three years’ practice demonstrates that these two sets of criteria are affective in raising the sampling and analytical quality. In this paper, they are given in full text for the sake of reference.

This paper is a. summarization of experience gained in the analysis of samples from the whole island undertaken jointly by five laboratories in the transprovincial contract project for 1:200,000 regional geochemical prospec ting of Hainan Island organized in 1986 by Ministry of Geology and Mineral Resources. It deals systematically with the understanding of such quality para meters as detection proportion, monitoring of standard samples of Grade I and Grade II, internal check and cipher sample check as well as the ex perience acquired in quality monitoring.In the aspect of how to guarantee the analytical quality, these understand ing and experience are probably of referential value to geologic laboratori es of various provinces which are performing analysis of 1:200,000 regional geochemical samples, geophysical parties which are undertaking the task of piecing together and compiling maps and, especially, laboratories which are jointly charged with the analysis of samples from the Hainan province.

Through quantitative statisties of axial azimuth angles of 1: 1,000,000 gra vity anomalies in Jilin province, this paper reveals the general regularity of distribution directions of the gravity anomalies and provides new information for research of regional geological structures.

This paper makes a brief description of the two developing stages that the National gravity reference system has experienced; the system of 1957 and that of 1958. It analyses the respective precision and main technical cha racters of these two systems and discusses two urgent and important practi cal problems that the national gravity reference system is faced with in its performance: 1) the evaluation of the precision of the old system and the trans formation of this system into the new one; 2) the data-processing method for various sorts of high-precision additional gravity measurement controlled by the new net, e. g., the Grade J National Gravity Net.

The dipole device has small electromagnetic coupling, and is a common device for amplitude-frequency induced polarization. Dipole quasi-cross section contains abundant information, and is therefore beneficial to raising inference level. Nevertheless, the insufficient research has affected giving full play to its role. For the purpose of solving this problem, we have made a systematic study on characteristics, laws and inference method of dipole anomalies. The basic results obtained are reported ill this paper, i. c. , the graph-source cor responding law of single-source quasi-cross section under the condition of horizontal topography.On the basis of describing and defining graphic characteristics of quasi-cross section, this paper gives the corresponding law between graph-source local characteristics of a set of low-tesistance sources under the condition of two-dimensional linear source and the corresponding law between the overall characteristics of a set of common graphs-sources. The former includes the corresponding law between upper, middle, lower characteristic points and up per, middle characteristic lines, whereas the latter includes saddle-peak law, valley distribution law, variation law of isostatic value, orthogonal law and symmetry corresponding law. .Finally, using model experimentation and mime rical calculation, the paper proves that the above laws arc also suitable for three-dimensional point source condition.

Based on the effects of integrated remote-sensing and ground geophysicalprospecting information interpretation method in such aspects as trailing wa-ter-bearing fractural linear structures, delineating water-bearing structures at contact zone and searching for concealed water-healing structures overlain by volcanic jocks, this paper deals with the establishment of the Water-search-ing methodological series consisting of remote-sensing (aerophoto interpreta-tion)-ground geophysir.nl prospecting (resistivity method or extremely low frequency method, a-card method, IP decay field method, shallow seismic method etc.), and expounds the necessity, rationality and possibility of the adoption of this series. It is thus pointed out that the three-dimensionality and multivariation of the hydrogeophysical information has become an impor tant subject for hydrogeophysicists.

Loess, paleosol and sandy loam make up the major lithologic characters of Quaternary sediments in loessial plateau of northern Shaanxi. As they are not obviously different from each other in conductivity and electrochemical activity, it is quite difficult to distinguish them accurately by means of ap parent resistivity logging curves and spontaneous logging curves. This paper applies such mathematical methods as regression analysis, discriminatory ana lysis and fussy cluster analysis to the lithological division of Quaternary sedi ments in loessial plateau of Northern Shaanxi. The fussy cluster analysis, in particular, shows quite good geological effects in distinguishing loess, paleosol and sandy loam.