Having consulted data of the two-dimensional velocity profile, the authors calculated the density layering structure along the Haicheng-Aohanqi-Bayanc-hagan section by using gravity model of variable density combinational body and automatic fitting method. According to an ’analysis of the lithologic variation characteristics of the crust and the mantle, it is held that the crust is basically characterized by the three-layer structure and that these layers are lithologically mixed with each other and show progressive and transitional relationship without distinct lithologic boundaries. The Moho in this region shows no obvious undulation which hence is not the main cause for variation in gravity anomalies. It is mainly the inhornoganeous distribution of the crus-tal and mantle materials and the layered structure that determine the shapes of gravity anomalies. The results of this research provide new basis for prognosis of geological structures and ore resources in this region.

With the engineering reconnaissance of Chenzhuang tunnel as an example, this paper deals with the feasibility of applying the integrated engineering geophysical method to the reconnaissance of this tunnel, describes field techniques of the integrated engineering geophysical prospecting ’ method in finding out geological conditions such as division of weathering bed, faults and distribution of gToundwater, and makes individual explanations and integrated explanation for results obtained by various geophysical prospecting methods. An inspection of the drilling data indicates that the effect is quite satisfactory. In addition, a discussion is given concerning the fault and collapse which are probably encountered in the process of tunnel excavation.

Using horizontal three-layer media as the model, this paper deals emphatically with the concealed layer and layer of inverted velocity encountered commonly in the study of first arrival refraction method: their formation condition and their influence on the precision of inversion interpretation. With the applications in Gezhou Dam and Shenzhen Airport as examples, this paper demonstrates that the utilization of the layer velocity and thickness in the survey area to the theoretical calculation helps to the quantitative judgment as to the feasibility of using intersection point method to evaluate effective velocity and the reliability of inversion interpretation of outcomes.

The authors describe in this paper the fundamentals of estimating relative paleomagnetic field intensity by the currently used nonthermomagetic met-hod, which utilizes DRM/ARM and/or DRM; SIRM as indicators in pa,leomag-netism of unconsolidated sediments. The feasibility and the advantage of ap-plying the method to speleothems (secondary deposits of limestone cave) are nga.Iso demonstrated. We applied the me thud to a stalagmite sample from Cruangxi, China and estimated the variation in relative intensity of paIeomagnetic field over the past 6000 years. "Che variation has three major features:1 .Several short-period oscillations of 1000 years are superimposed on a longer-periori oscillation.2. There are fiva maximum peaks and five minimum peaks in the variation.3. The present }eo:na}netic field intensity approaches the minimum value.

The author has collected several thousand specimens from the granite zone of this province and measured their physical propetty parametesr. For the purpose of predicting ore potentiality of the rock body, he has studied the correlation between these physical property parameters and the chemical composition of the rock body and, with the help of discriminant analysis and correlation analysis, made classification for the graintes in this province according to their properties. Using physical property parameters, he has also conducted researches on the division of strata in tvo areas of sedimentary rocks.Large quantities of data obtained from practice demonstrate that the regional physical property work is of great prospects in the direct solution of some geological problems.

Based on correlation between high-predsion aeromagnetlc local allomallesand faults in covenng strata In nortlleffi part of centralHchel and through acomparison witll seismic data and direct fitting calctilation, this paper makesa detdlodanalysls of tile prerequlsite and geologicaf factors with which thefaults in covering strata may arollse local magnetic atomanelies,and thus indi-cates the posslbility of using high-precision aeromanetic data to detect faultsIn covedng strata as wu asdle prlncl“es and methods for division. It is alsopointed out in this paper that the perfect coincidence betwee the clusteredweak local magnetic anomalous zones and the faults In covering strata willprovide lmportant basls for using high-precision aelomagnetic survey ln deter-mining faults In covering strata.

Based on theoretical and experimental work, the authors argue for the reliability of utilizing the quartic exponent method to determine noise level of the high-precision magnetometer, and also indicate the effectiveness of the quartic exponent difference method in discriminating erroneous data in observations.

Based on statistical analysis of large quantities of geochemical data collected in western Yunnan, this paper gives a detailed summarization of the distribution pattern of Sn-related elemental anomalies and anomaly associations along the Western Yunnan tin ore belt and then classifies geochemical anomaly associations and divides geochemical zones in western Yunnan. It names this area"Western Yunnan geochemical proviuce"and delineates ten geochemical zones, thus providing geochemical basis for further research on tin deposfts in western Yunnan or even in its northward extension to Tibetan area.

This paper deals with geochemical characteristics of alkali metal elements in soils of the Yangbajing high-temperature geothermal field and its neighboring area of 90 km². Studies show that alkali metal elements Li, Kb and Cs can serve as a set of new geochemical indicators for the thermal field exploration and the delineation of thermal field limits,and their function is similar to that of such geochemical indicators as Hg, As, Sb and Bi. Apreliminary discussion is made concerning the distribution and geochemical behavior of alkali metal elements in geothermal system and the cause for the formation of anomalies. Correlation analysis demonstrates that these geochemical indicators have intimate correlationship, suggesting their common origin. Using Na and K. in the thermal water as geothermal temperature indexes, the authors have made an estimation of the temperature of underground hot water in the Yangbajing thermal field.

The porphyry type deposits in southeastern Hubei area are associated with intermediate-acid supergene small intrusive bodies. With the principles and methods of fuzzy mathematics, this paper, using F-PFScluster method, has established a fuzzy cluster recognition model for information of small rock bodies reflected by geochemical parameters, thus realizing the evaluation of ore potentiality for small rock bodies and the rapid choice of target areas. This is undoubtedly of practical signifance to the exploration of ore resources.