Influence of Cr on REE Partitioning between Garnet and Silicate Melt: Application to Metasomatism of Mineral Inclusions in Diamonds

Abstract

Partitioning of REE between garnet and basaltic melt was performed at 7. 5GPa and 1900∼2090°C, considering the possible influence of Cr. It was confirmed that compatibility of light REE in Cr-bearing garnet increases significantly as comparing with that of Cr-free system, but no evident variation was detected for heavy REE. Based on the newly established partition coefficients, it is concluded that the light REE-enriched garnet inclusions in diamonds have not achieved equilibrium with metasomatic melts. Bulk mixing and subsequent recrystallization could be the main processes for the mineral inclusions in diamonds.