plenty of geophysical data have been recently obtained in Qinghai-Tibet region, including the results of Sino-French joint study conducted in 1980-1982. The Qinghai-Tibet plateau is a unified geological element and may be divided into three belts according to its structural activities:the center is a uniformly uplifted block in isostatic status, while the northern and southern margins, having been subjected to intense compression and overlapping, are differential uplifts not yet reaching an isostasy. Its structural forms consist of three stru ctural layers with the upper (upper crust) dominated mainly by overlapping, the middle (lower crust) by compression, and the lower (anomalous mantle) by uplifting. An intracrustal layer of low-velocity and low-resistivity exists between the upper and lower crust, being a major sliding plane. The geological evolution of this plateau might have experienced two stages: before the collision between Indian and Tibetan plates, buoyancy of the anomalous mantle caused the pla teau to uplift gently;after the collision, the crust thickened and the plateau uplifted rapidly owing to the isostasy.

During the sixth five-year-plan period, especially since the opening to the world of 14 coastal ports as decided by the State Council in 1984, 1:50,000 re gional geophysical survey has been conducted for 38 large or medium-sized ci ties with the help of such traditional geophysical techniques as aeromagnetic survey, gravity survey and electrical sounding. The results provide data of esse ntial importance for basic geology, engineering geology as well as investigationof underground water and geothermal resources, showing remarkable social and economic benefit. For the purpose of adapting geophysical work to extensive and many-sided requirements of modern urban construction, the author proposes in this paper the substance, methods and procedure for a new round of urban geo physical prospecting, which include seismic intensity zoning, investigation of fault activity, layering and regionalization for rock-soil mechanics of ground, regional survey of bed rock, fracture water and concealed geothermal areas. The develop ment of a new round of urban regional geophysical prospecting in its substance, methods and procedure will undoubtedly raise the urban regional geophysical prospecting and its social and economic benefit to a new level.

Samples of Permian basalt and bauxite were collected at six sampling sites in Panzhihua-Xichang area of Sichuan Province. The paleomagnetic measure ments indicate that the strata at different sites have consistent characteristic mean magnetic directions, with the geomagnetic polarity being either positive or reversed. A further analysis implies that the Emeishan basalt that lies in NE quadrant was formed at the positive polarity interval.A discussion is also given as to some differences in magnetic properties of the strata between the two sides of the Anninhe fault. It is considered that these differences in characteristic magnetic direction might have arisen from structural activity or disparity in age of strata.

Based on the distribution of metallogenic and associated elements in strata, rocks, ores and minerals of the ore district, the primary halos of the deposit, the sulfur and lead isotope compositions of the ores, and retios of elements re flecting environmental characteristics, combined with geological setting of the deposit, this paper summarizes the geological-geochemical environment for the formation of rocks, ores and halos, the material sources for mineralization and behaviours of late-stage hydrothermal elements,indicating evidently that this deposit is of stratabound type dominated by sedimentary enrichment.

The effects of such geochemical methods as soil survey, rock survey and stream sediment survey in large-area geothermal prospecting are dealt with and compared in this paper. It is demonstrated that geochemical soil survey and stream sediment survey yield the best results, while geuchemical rock survey also gives pretty good effect. The indicator elements consist of Hg, As, Sb. A dis cussion is made on the potentiality of the Rehai geothermal field in the light of exploration geochemistry, indicating that as this geothermal field is charac terized by large size, high temperature and considerable reserves, there exists bright prospect for its exploitation and utilization.

This paper discusses a new log evaluation method for carbonate oil reservo irs used in such aspects as the evaluation of the formation properties of carbon ate oil reservoirs, the determination of water-oil interface, the identification of fracture trend and the estimation of petroleum reserves and oil-well production potential. Good results have already achieved by using this new method.

In the light of geological, geophysical and geochemical characteristics of several typical ore deposits in eastern Shandong, Henan and Guangdong, com bined with some geophysical and geochemicaJ techniques which have been proved to be effective in utilization, this paper proposes preliminarily the coordination of geophysical and geochemicaJ prospecting methods and advances an ore pros pecting model for the purpose of detecting more altered rock type gold deposits in the near future.