Spatio-chronological position of Precambrian uranium deposits

Radiological dating analysis of all known uranium deposits of the Precambrian has made it possible to single out seven main epochs of uranium ore formation, each one characteristic of certain ore component complexes. Aside from these, long periods with practically no ore formation have been observed. Workable uranium ore deposits are generated in mobile belts and in areas of disturbed cratons. The non-activated Archaean cratons are practically oreless. The activated structures are subdivided into taphrogenic basins and areas of tectono-magmatic activity. The former accommodate most large deposits, the latter complex deposits where the uranium is associated with rare and rare earth elements. The uranium bearing regions and provinces accommodating large uranium deposits are characterized by specific geotectonic, petrological and mineral-geochemical peculiarities. Knowledge of these makes it possible to forecast certain types of workable deposit and to outline efficient exploration programmes. (author). 12 refs, 2 tabs