REE MINERALS IN CARBONATITES OF THE ARSHAN DEPOSIT, WESTERN TRANSBAIKALIAN REGION

Abstract

The fault-line REE-bearing carbonatites of the Arshan deposit were described for the first time twenty years ago (Bulnaev, 1985, 2000). The elevated REE contents were explained by the occurrence of bastnaesite and allanite. Fine parisite grains after bastnaesite phenocrysts were noted as well (Ripp et al., 2000). In the present study, parisite and allanite replacing bastnaesite were examined with SEM/EDS. The investigation has shown the metasomatic origin of both minerals and their essentially cerium composition. Sm, Eu, Gd, Dy, and Yb in amounts of n(0.001 0.1)% were detected with spectrochemical analysis.