Formation of uranium deposits

The beginning of the uranium province formation could be determined as being concurrent with differentiation of the Earth's substance. Those parts of the nebula of the condensed Earth in which the concentration of the radioactive elements was stronger were heated earlier by the radiogenic heat released. This created conditions for an earlier upward migration in this part of the nebula via radioactive metal convection towards the Earth's crust. Thus, even in the initial stage of the terrestrial globe's zonal formation between 4600 and 360 million years ago, separate sections of the mantle and primitive Earth's crust were relatively enriched with radioactive metals. The crust's reformation by anatexis, magnetic differentiation, weathering, sedimentation and radioactive metal extraction contributed to the uranium enrichment of some rocks. The earlier differentiation of the primitive Earth's crust, which has lower density and higher uranium content, is an important factor in the formation of the uranium provinces. This differentiation was the first phase of a series of remobilizing processes. The uranium concentration in these areas of the Earth's crust depends on the intensity of the remobilizing processes and their multiphased nature. The uranium concentration in these parts of the crust is higher, thereby the second cycle of uranium province formation is almost completed. The processes of uranium mobilization from the local sources and its fixation (concentration) in deposits characterizes the fourth and last cycle of uranium province formation. Six uranium provinces have been recognized: South African, South Sahara, North Australian, Colorado-Wyoming, Middle European and Canadian. Some of these uranium provinces comprise several subprovinces. 13 refs, 3 figs, 1 tab