STRONGLY FRACTIONATED REE PATTERNS IN SALTS AND THEIR IMPLICATIONS FOR REE MIGRATION IN CHLORIDE-RICH BRINES AT ELEVATED-TEMPERATURES AND PRESSURES

Rare earth element (REE) distribution patterns have been determined in a salt profile adjacent to a basaltic intrusion. The REE concentratio ns in the salts are in the ppb range, which required an enrichment pri or to ICP-MS analysis. The results document a strong REE fractionation with increasing distance from the basalt contact which could be due t o REE-chloride solution complexation. The observed fractionation occur red at elevated temperatures and pressures and indicates a higher mobi lity of Ce, Pr, Nd, Sm and Eu. This finding is of interest for basic r esearch and for the disposal of nuclear waste in salt formations. ((C) Academie des sciences / Elsevier, Paris.)