The tactics of exploration of buried non-ferrous metallic ore deposits is deviding the exploration into several stages with each stage having given geological problems to be solved in order to delineate a smaller area to do more detail work in the next stage and finally to search for ore body in a very small area. For example, an exploration is carried out in an area of 5 million squre km, it is assumed that each stage will delineate an area of 5% of the work area to do more detail work in the next stage, calculation shows that after the fifth stage the work area is 1.5625 squre km. To solve the geological problems in each stage, it is necessary to know something about the buried geological features which can't be seen on the ground surface and is predicated by the geologic features seen on the ground surface. Now the problems arise. Firstly, predication of space geologic features by surface geologic features is a problem of multiple soluions. Secondly, no geologic features can be seen when the rocks are covered by soil or water or the observed geologic features having no relation with the deep geologic features when the deep rocks are covered by younger rocks. Thirdly, it is impossible to map the deep geologic features by drilling and digging as it is too expensive when the work area is large. These difficulties can only be conquered with the help of geophysical exploration and now geophysical exploration is successfully used to solve the geological problem in the exploration.
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