Marcos Bonotto, Daniel [UNESP]2014-05-272014-05-271989-05-30Journal of Hydrology, v. 107, n. 1-4, p. 155-168, 1989.0022-1694http://hdl.handle.net/11449/63903Groundwater samples were collected for several months in boreholes drilled at Morro do Ferro, a thorium and rare earth deposit located on the Poços de Caldas Plateau, Minas Gerais State, Brazil. An aquifer system has developed in the weathered mantle due to in situ intense alteration. The weathered zone includes a thick argillaceous laterite greater than 100 m thick. The U content and 324U/238U activity ratio were measured in the groundwater samples and in spoil samples of a borehole drilled in the ore body. Some possible mechanisms related to the mobilization of uranium are considered such as complexation with humic substances and adsorption by clays. © 1989.155-168engThorium Deposits--BrazilUranium Compounds--SolubilityArgillaceous LateriteHigh-Grade ThoriumSubsurface FlowWeathering ProcessesWater, Undergroundadsorption by clayaquifer systemcomplexation with humic substancedissolved uraniumgroundwatergroundwater qualitythorium deposituranium isotopeuranium mobilizationuranium-234/uranium-238 activity ratioweathered zoneBrazil, Minas Gerais State, Pocos de Caldas Plateau, Morro do FerroBrazil, Pacos de Caldes Plateau, Morro de FerroArtigo10.1016/0022-1694(89)90056-5Acesso restrito2-s2.0-00244757897430102726026121