Aimed at solving the problems that exist in the geocliemical anomaly examination work conducted by various provincial bureaus of Ministry of Geology and Mineral Resources, this paper suggests a method for classifica tion, appraisal and examination of geochemical anomalies and advances some opinions on the reasonable working procedures for these three steps. The purpose and task of each verification stage in the three-stage verification of geochemical anomalies are also given in this paper. It lays emphasis on the importance of follow-up for anomaly sources in stream sediments at the ano maly reconnaissance and examination stage and puts forward five common methods of in-situ follow-up for anomaly sources.

By utilizing mass spectrographic technique, the author has developed a 36 channel AC analytical apparatus. It has such advantages as rapid, accurate, cheap and practical, and is therefore an effective device in large-scale geoche-mical oil prospecting. This paper gives detailed data on the exploration ef fectiveness and analytical quality of the soil AC method used in geochemical oil-gas prospectig. It also poses some problems which deserve further investi gation.

The main tasks of geophysical prospecting techniques in search for golddeposits are detection of or--controlling fault zonesl fracture zones and altera-tion zones, delineation of ore-bearing rock bodies and strata, determination of weak mineralization zones and search for quartz veins and other ore-bearing veins. Such traditional techniques as gravity, magnetic method, induced polari zation method and extremely low frequency electromagentic method all prove to be effective. Tests show that piezoelectric method, radio method and seis mic induced polarization method are quite promising. In addition, the study of thermoelectricity and thermoluminescent characteristics of rocks and mine rals is a new subject which deserves due consideration and will play an acti ve role in prognosis of ore resources and evaluation of ore potential.

Magnetic survey can play a quite satisfactory role in the search for gold deposits at various stages from regional reconnaissance to detailed exploration. With some examples on the eastern. Shandong gold ore belt, this paper demon strates that magnetic survey can be employed to detect gold-related fault structures and fractural alteration zones, and delineate contact zones of different rocks as well as distribution limits of intrusive bodies. Combined with other geophysical-geochemical prospecting methods and in coordination with geolo gical mapping, it can attain the aim of finding gold deposits.

The extremely low-frequency electromagnetic method is a rapid techni que requiring only portable devices. In 1:50,000 hydrogeological survey, this method, in combination with the aerophoto interpretation, has proved to be effective in investigating regional structures at the early stage of hydrogeolo gical survey. In the exploration of fissure water in bedrock, the adoption of detailed extremely low-frequency survey, together with some IP sounding work, can reveal locality and attitude of the fissurecrowded zone and conduct water abundance analysis, thus providing valuable information for drilling.

In order to suit the needs of the rapidly developing tourism in Hangzhou and improve the water quality of the West Lake, the Hangzhou Municipality hewed a tunnel and diverted water from the Qiantangjiang River to the West Lake to replace the original water in the West Lake.The worsening water quality of the lake is mainly attributable to the increasing organic substances and mineral matters in water, i. e., the increase in mineralization intensity of the water. The mineralization intensity of water, however, is approximately in linear relationship with its apparent resistivity. Therefore, we can use the apparent resistivity method to monitor the water-changing Work. From the equi-apparent resistivity graph of water that has been drawn, we can know the dynamic variation of changing water, i. e., the shape of mixed flow. As the concentration of substances in lake water and the variation in apparent resistivity obey the infinite dilution law, namely, the negative exponent attenuation law, we may establish a methmatical model and thus reveal the motion law of mixed flow theoretically.Based on the observation result and mathematic model, this paper also makes a tentative discussion on the economical and reasonable water-changing method.

The reconnaissance, preliminary exploration and additional exploration for the Mengyejing rock salt (potash salt) deposit has lasted for 13 years. Field work was conducted twice in the ore district and its outskirts, and the result was repeatedly interpreted; following the additional exploration, researches were made again. This paper makes an account of the geological outcomes gained in geophysical prospecting work at various stages.Geophysical and geochemical prospecting techniques were tried out at the early stage of geological reconnaissance, and it was demonstrated that gravity survey in coordination with electrical sounding was an effective method for direct search of salt. The depth, thickness, spatial form and estimated prospe ctive reserves inferred from geophysical prospecting results were mostly con firmed by preliminary exploration.Geophysical prospecting work was once more performed before the addi tional exploration; anomalies were reexamined; data of the ore district was collected; geophysical results were reinterpreted; and the boundary of the orebody was delimited. The argument was put forward that the drill hole hadalready passed through the rock salt bed and no salt could be found at the depth of northern flank. This provided data for "exploring the depth and the margin" in the geological work. The gamma-ray energy spectral logging divided the potash salt bed with effectiveness. It has been proved that the integrated study by combining geophysical prospecting with geological data and data of saline spring chemistry can classify the salt (potash salt) ore prospective areas.Through geophysical prospecting work for rock salt (potash salt) depo sits, we have summarized a suite of reasonable geological and geophysical pros pecting procedures, which play the function of reducing target areas, accelera ting the course of the work and cutting down the investment, thus yielding good economic benefits.

This paper puts forward a model of oblique bedded media suitable for shallow geological structures, with the corresponding virtual ray model estab lished. On such a basis, a set of inversion recurrence formulae has been deri ved. The evaluation of related parameters is discussed, and the inversion ima ging of common starting point or common refraction point of refraction waves has been realized which is generally suitable for various oblique bedded refra ction boundaries.