F-radiographic study of uranium distribution in iron hydroxides from crusts of weathering

Presented are the results of study of uranium concentrations and peculiarities of its distribution in iron hydroxides from crusts of weathering of aluminium silicate and carbonate rocks. The age of one crusts of weathering is Quaternary, of others - Tertiary. The effect of climatic conditions, composition of source rocks, hydrochemical zoning of the crust of weathering on the uranium fixation by iron hydroxides has been studied. Gamma-spectroscopy, luminescence and autoradiography methods have been used. The mechanism of formation of increased uranium concentrations in iron hydroxides is considered. A conclusion is made that increased uranium concentrations in iron hydroxides may appear in the process of weathering both of aluminium-silicate and carbonate-containing rocks as a result of uranium sorption by fine dispersed iron hydrates. The use of iron hydroxides with increased (anomalous) uranium concentrations as a direct search feature without additional investigations can lead to wrong conclusions