The mobility of U, Ra and Rn in a granitic batholith on the Canadian Shield

Analyses of groundwaters in overburden and bedrock in the Lac du Bonnet granite, southeastern Manitoba, have indicated the concentrations, distributions, sources, and geochemical controls of U, Ra, and Rn. The results indicate significant U concentrations in groundwater in the upper 100-200 m of rock and considerably reduced concentrations below this depth. Radium shows the opposite features, tending to higher concentrations at depth. Radon is a good indicator of localized enrichments of Ra (and U). All three elements are useful in defining actinide mobilities, geochemical processes and hydrogeological regimes that exist in the upper 1000 m of the granitic batholith. (orig.)