In China, shallow-sea oil and gas geochemical exploration has just begun and is only being conducted on a small scale; nevertheless, the work has a bright future. Based on our practice in Pinghu area of the East China Sea,the present paper has made a fairly systematic description of the development of shallow-sea oil and gas geochemical exploration and its methods and techniques as well as the preliminary achievementns obtained. A brief discussion is also given on the affecting factors and problems related to the inference and interpretation.

This paper has recounted the application of gas survey to underground channel line and reservoir area exploration in four periods of the Yellow River water-drawing project, with emphasis placed on the effects of soil gas Hg and Rn. Drilling inspection and shallow seimic verification of known anomalies have unexceptionally yielded fairly good geological results, which shows that, when used in engineering geological exploration, gas survey is economical, rapid, directly perceivable and effective, suggesting that this method will be employed more extensively in future.

Metallogenic model of ore deposits constitute one of the problems that have aroused much interest in research work. There exist a great variety of geological ore-prospecting models and patterns as well as a number of geochemical ore-prospecting models. Nevertheless, these models are generally established on the basis of primary halos of ore deposits. whereas regional geochemical anomaly models of ore deposits or orefields established on the basis of regional geochemistry are relatively rare. With the ore field as the basic research unit and the 1: 200000 regional geochemical data as the basis, the present paper has studied regional geological and geochemical environments for mineralization from regional geological setting of the orefield as well as distribution regularity of positive and negative regional geochemical anomalies of 39 elements. It has been discovered that the spatial distribution of anomaly associations of ore-forming elements, anomaly associations of indicator elements and anomaly associations of elements in metallogenic environments exhibits unique structural characteristics in the orefield. On such a basis, the present paper has put forward the concept of anomaly structural model and, furthermore, the regional geological-geochemical anomaly structural model of the Zijinshan orefield.

Based on distribution of elements in such media as rocks and ores within the Jiguanzui copper-gold deposit,this paper has illustrated geochemical characteristics of the ore deposit and determined indicator elements related to the ore deposit as well as zonal sequence of elements. Applying the regularity that multiplicative ratios of supraore and subore element groups gradually decrease from the upper part downward,the paper has established indices for appraisal of anomalies and formulated the conceptual model for exploration geochemical anomalies of this ore deposit.

The distribution regUlarity of radionuclides Th,U and K in strata is related to litholigic character,mineral composition, diagenetic environment and groundwater activity.On the basis Of natural gamma spectra and indoor analyses of 646 core samples from 27 deep drill holes in Sanzhao area and through database management system of natural gamma spectra,the authors succeeded in drawing Th-U intersection diagram and Th-K intersection diagram,thus finding out the relationship between natural gamma spectra and lithologic character.

Genetic algorithm is a constrained stochastic optimization method. Compared with traditional deterministic optimization method, it has the merits of realizing overall convergence with no need of calculating partial derivatives of objective functions; compared with traditional stochastic optimization method, it has the advantages of high search efficiency and implication parallel calculation. The present paper deals with the basic principles of genetic algorithm and procedures of iterative calculation, followed by a discussion on the application results of this method in the constrained inverse problem of magnetic intensity.

The mathematic principle of principal component analysis method (PCA) lies in coordinate conversion.In practice,it provides a means of variable combination for integrated interpretation. The present paper has made a generalized description of basic principle of the principal component analysis method as well as analytical programscompiled by ourselves. Exemplified by northern Tarim area of Xinjiang,the paper has also illustrated the achievements gained in layering,calculation of argillaceous material content and porosity.

The present paper deals with the errors existent in routine datum plane statics under the condition of complex topography as well as the cause for the errors. The author puts forward a new field statics method-floating datum plane statics, which can completely eliminate the errors existent in the routine datum plane statics method and improve the quality of the seismic time profile as well as its interpretation precision.

The apparent resistivity of dual-frequency electromagnetic sounding is a new method of geoelectric measurement with dual-frequency electromagnetic wave. By analysing apparent resistivtiy curves of various geoelectric sections, the present paper has proved the practicability of this method.Being the monodrome function of electromagnetic response, the apparent resistivity can objectively describe electric characteristics of the geoelectric section,suppress the interference of background field, and highlight geoelectric anomalies. Its capacity for distinguishing strata and its characteristics can meet the requirements of sounding.

This paper has discussed the image reconstruction of electric resistivity by Zohdy inversion.Zohdy inversion was advancd on the basis of surface surveying data; numerical modeling and field data inversion proved it to be simple,easy to handle,low in calculation cost,high in resolution and ideal in result. It is hence quite possible to use it in resistivity tomography of field surface surveying. Using Fortran Language, the authors made programming for realizing the aboe process, and used the 2. 5 dimensional finite element method in forward modeling. To improve the image results, they mapped the inversion data ny false color image processing technique.