Preliminary results of REE-Y sorption on carbonate rocks

Résumé

The Rare Earth Elements and Yttrium (REE-Y) have recently been proposed as good proxies for identifying rupture zones on carbonate fault scarps. Indeed, fluctuations in the REE-Y concentrations along a fault plane may be linked to the number and size of earthquakes that ruptured the fault. The enrichment is attributed to the contact of the soil with the carbonate fault scarp. Our study presents preliminary results from a series of experiments that aim to shed light on the mechanism associated with the REE-Y sorption on the limestone-soil interface. Rain simulation pot experiments, kinetic and isotherm batch experiments were employed to describe the mechanism of REE-Y sorption in calcite. Results reveal fast REE-Y sorption on the limestone surface after the simulation of five years of rainfall. The fast REE-Y sorption is also supported by the kinetic experiments. Isotherm tests show the higher affinity of calcite in the Light Rare Earth (LREE) compared to the Heavy Rare Earth Elements (HREE). The sorption of the REE in the form of carbonate complexes is proposed as a plausible mechanism of REE-Y incorporation into the limestone.