EVIDENCE FOR EVOLUTION OF DIAMOND CRYSTALLIZATION MEDIUM IN ECLOGITE XENOLITH FROM THE UDACHNAYA KIMBERLITE PIPE, YAKUTIA

Abstract

The recently obtained data on the superimposed character of diamonds in eclogite xenoliths have compelled us to consider the problem of diamond formation in the upper mantle from a new standpoint. We reported the first results of the study of a unique diamond-bearing xenolith (length18 cm, weight 6900 g) from the Udachnaya kimberlite pipe (Yakutia). The results testify to the superimposed character of diamonds (particularly, the chemistry of minerals) and suggest that diamond crystallized as a product of interaction between the high-K and C-bearing fluid with the ultramafic substrate. The study of diamond-hosted inclusions from xenoliths and the comparison of their chemical composition with minerals of the xenolith groundmass would be of special interest for reconstructing conditions of formation, composition, and evolution of diamond. In this communication, we present results of the study of inclusions along with defects, impurities, and the internal structure of diamond from this xenolith.