1991 is the first year of China's eighth "Five-Year Plan", and many new research projects of exploration geophysics began to be put into practice after demonstration and approval. Less new scientific and technical achievements were gained in 1991 compared with what hud been achieved in the last two years of the seventh"Five-Vear Plan". In 1991, aerogeophysical and marine geophysical exploration, seismic exploration for oil and gas and regional gravity exploration had approximately the same number of research workers as work of these bran-ches in 1990, with somewhat larger amount of work completed. In the aspects of ground electrical method and shallow seismic exploration, quite a lot of new instruments were developed, mostly based on the improvement of instruments produced in recent years, which exhibited a good tendency of rapid renovation. In the fields of large-sized seismic and logging collection system, quite a number of new products were put into production in 1990, and therefore new designs were relatively few in 1991. Greater importance was attached to the application of geophysical technique to the development of oil-gas fields and coalfields, and the application of this technique to engineering exploration and environ-mental investigation continued to row vigorously. The new method "continental sonar"developed by Chinese scientists began to be used in engineering explora-tion. Various new processing and interpretation methods, softwares and systems successively came into being and developed coward the combined processing and interpretation of diversified methods and data.

Statistical study of the triplicate analytical data shows a general tendency that subsampling error is comparatively low for samples with Au value 1-10 ppb. The error increases in the medium Au value range. For higher Au value range, the subsampling error decreases again. This can be attributed to the follo-wing reasons; (1) in the samples with low Au value, the gold particles are very small; (2) in the samples with medium Au value, the subsampling error is dependent on gold particle size: if gold particles are in ultrafine size, the subsampling errors will be insignificant, but if there are unevenly distributed macroscopic particles, the subsampling errors will be great; and(3) in the samples with higher Au value, the macroscopic particles are abundant, so the subsampling errois are low.Although there exist great variations among the triplicate analytical data of individual samples, the trend, shape, intensity and dimensions of an anomaly re-main consistent.

Studies show that primary hatos of this ore deposit have the following characteristics; (1) anomalies cover a large area, and the concentration centers enclose all the auriferous breccia bodies; (2) the components are complex and show obvious zoning; (3) ore-bearing breccia and porphyry as well as compo-sitionally complicated breccia contain relatively abundant gold, which, however, is highest in pyrite; (4)trace element contents and their ratios vary noticeably with the varying extent of denudation; (5) gold and major accompanying elements migrated in the form of CM-CD or [M-HS] and, under the reduction condition of falling temperature, decreasing pressure, dilution and conversion from weak acidity to weak alkalinity, elements precipitated in order of Mo, Cu, Au, Ag and Pb, forming the main framework of the element precipitation zoning.

Using the instrumental neutron activation analysis and the newly-designed geogas collection device, we performed geogas survey and anomaly investigation over the Dongji gold deposit in Shandong Province.It seems that INAA is superior to PIXE so far as the prospecting for con-cealed gold deposits is concerned.There are obvious geogas anomalies of such elements as La,k, Na, Fe,Sc, Au, As, Cr, Sb and Zn over the structural ore-bearing belt;anomalies of Au, As, Cr,Sb,Zn and some other elements exist over concealed ore deposits. Anomalies of these metallic elements serve as a good direct indicator for subsurface gold mineralization.

In accordance with the reality of the two-hole electromagnetic method, the authors have established a numerical model for the scattering of a number of anomalous bodies (including nonuniform anomalous bodies). A method for handling relationship between serial number of blocking and coordinate is given, which renders the computer program commonly usable to some extent. The moments method is used to solve the volume integral equation; appropriate approximate formulae are adopted to calculate the distribution of scattering fields of various anomalous bodies under the condition of different working frequencies. From the calculations some conclusions may be drawn which are worth considering in the interpretation of measured data.

The characteristics, structure and field preliminary application of DJJ-1 type borehole induced polarization instrument are introduced in this paper.