In this paper, a review has first been made as to the achievements scored during recent years in such aspects as aerogeophysical prospecting, regional gravity survey, geophysical prospecting for metallic and nonmetallic ore deposits as well as for coal basin, hydrologic and engineering geophysical exploration, and geophysical survey for information at great depths, with an enumeration of geologic results achieved and methods and instruments newlyadded for utilization, then some tentative ideas have been put forward concerning the future work, arguing that geophysical exploration should be advanced to a new stage to achieve four objectives; discussion is also given on some important subjects, e. g., to conduct the second-generation aerogeophysical work; to extend the regional gravity prospecting to complicated areas; to perform 1:50,000 integrated geophysical survey as an important component part of the geophysical prospecting work; to speed up the geophysical work in aspects of hydrologic engineering prospecting and geothermal prospecting; to enable geophysical prospecting for metallic and nonmetallic deposits to tackle increasingly complicated and variable problems; to further strengthen geophysical prospecting for coal basins; and to work out a long-term plan of deep-seated geophysical survey for systematical work. At the end of the paper, some expectations have been made for improving techniques and instruments.

Thirty years have elapsed since tie nationwide petroleum reconnaissance announced its beginning in North China Plain in 1955 During tiis period, integrated geophysical survey has been carried out in dozens of continental or off-siore depositional basins with the discovery of hundreds of structural traps of various types, of which some one hundred have proved by later investigation and exploration to be oil fields of commercial value; nevertheless, the geophysical work in this thirty years, named "the first round petroleum geophysical reconnaissance", has been predominantly confined to various anticlinal traps within Mesozoic and Cenozoic detrital sequence of East China. Starting in about 1982, the second round petroleum geophysical reconnaissance extends the investigation and research work to new areas, new depths, new realm and new types with the aim of looking into complex structures and stratigraphic traps. To fulfil the task assigned to tiis round, full use should be made of the experience gained in the first round, such as spreading the survey to the whole region, integrated exploration with seismic prospecting as the major method, and integrated evalution. Tie present paper also maintains that tie successful realization of tie new objectives requires new viewpoints, new equipments, new techniques and newly-trained personnel.

The present paper reviews the advances in research and production work exploration geochemistry gained by Ministry of Geology and Mineral Resources over the past thirty years, especially during the recent years. It deals with such aspects as effectiveness of geochemical prospecting for mineral deposits, regional geochemical exploration, geochemical survey in metallogenic belts, geochemical prospecting in mining areas, standard geochemical reference samples, analytical devices and methods for geochemical prospecting and mercury vapor survey. Marked progress has been made in the field of geochemical exploration in the past five years, as evidenced by the detection of not only more quantities but also more types of ore deposits and ore occurrences than ever before, with the discovery of 24 gold deposits or occurrences as the most convincing example. The progress in designing an integrated plan for analysis of multiple elements in regional geochemical samples and its role in geochemical prospecting have been emphatically elucidated. The available data fully show that, as a useful direct ore-detection method, geochemical prospecting widens geologists' visual field, enables them to search for ore at greater depths, and is therefore surely to play an increasingly important role in geological work in the days to come.

This paper presents some valuable results obtained in experimental geoc-bemical exploration work in tbe arid area of Inner Mongolia. Surface soil and drainage sediments in tbe arid area of Inner Mongolia and western Gansu are commonly mixed with aeolian (wind-borne) sand, whose interference reduces element contents of geocbemical samples nearly to background values. Aimed at eliminating the effect of this aeolian sand, we have graded the geochemical samples according to grain size, calculated tbe proportion possessed by eachsize fraction, made microscopic identification for genesis and determined contents of various elements. The resulting data suggest that aeolian sand is predominantly of -0.9-+0.2 mm in size and the optimum sampling size seems to be -5-+2 mm-samples in this size range show high anomalous values with small variation coeJficients and fine recurrence. Investigation has also been made on such problems as optimum sampling site, sampling horizon and sampling density, combined with a comparison of effectiveness between soil survey, rock survey, hydrochemical survey and some other geochemical methods. Ail this has led to the conclusion that, in arid and desert areas, the most economical and efficient regional geochemical prospecting methods are drainage sediment survey of coarse-sized fraction and underground hydroche mical survey, whereas in peneplane or denuded gobi areas the optimum sampling media are rocks and underground water, with soil being secondary in importance.

/With a view to further ascertaining tie relative position of the Sino-Korea Plate in late Paleozoic Era and investigating the migration of various plates in Asia, a total of 70 paleomagnetic hand specimens of Carboniferous and Permian sediments were collected along the Qiligou section and the West Valley (Due-rping) section at Xishan, Taiyuan on Shanxi anteclise which, lying in the middle of the North China Platform, were relatively stable during the late evolution stage of the platform. These hand specimens were cut into 140 samples which, after being subjected to heating demagnetization, were measured for remanent magnetization one by one. The average magnetization, paleolatitude and paleopole for every sampling site were thus obtained.The data acquired indicate the following facts. (1) Average paleolatitude of sampling sites during Permian was 24.9° and the difference in latitude between Sino-Korea Plate and Siberia Plate at that time was about 1200km larger than the present difference; paleolatitude in Carboniferous was averagely 16.2° and the difference in latitude between these two plates was some 2100km larger than the present difference. It is tentatively presumed that the Sino-Korea Plate must have lain within low-latitude area in late Paleozoic, in the process of migration from low latitude to high latitude. (2) The formerly-defined Permian strata are of negative polarity with the exception of the middle portion of Shiqianfeng Formation which possesses positive polarity. This formation, according to a comparison of documents available, is preliminarily assigned to Triassic.

Theoretical investigation, model test and analysis of the data available all suggest that the research on complex resistivity spectra is subject to certain limitations if only amplitude spectrum and phase spectrum are used. As a remedy, an integrated utilization of amplitude, phase as well as real and imaginary component spectra makes it possible to derive the reliable initial values of such spectral I. P. Parameters as r, m and c by means of simple procedures in fitting and inversion computations, which in turn will contribute to a further shortening of the fitting and inversion process.