GEOCHEMICAL EVIDENCE OF THE INFLUENCE OF SUBDUCTEDCRUST IN THE PROCESS OF MODIFYING SUBCONTINENTALMANTLE YAKUTIAN DIAMONDIFEROUS PROVINCE
Available data indicate a complex evolution of deformed peridotites from mantle xenoliths, which PT parameters indicate that they are fragments of the metasomatized lower part of the craton lithosphere. The zonality established in garnets of such xenoliths from kimberlite pipes is interpreted as a result of metasomatism that occurred shortly before xenoliths hit the surface. Metasomatism in xenoliths of deformed harzburgites is manifested not only in the appearance of zoning of minerals. The studies show that there is a discrepancy between the calculated data based on the contents of incompatible elements in xenolith minerals and the concentration of direct measurements of the bulk composition of xenoliths. In order to determine the balance of incompatible elements, we carried out experiments on leaching xenoliths of deformed lherzolites from the Udachnaya kimberlite pipe. It was found that a significant part of light REE in the studied xenoliths is present in intergranular space. The nature of the distribution of incompatible elements and, in particular, the presence of a positive Eu anomaly clearly indicates that the appearance of the intergranular component is not associated with kimberlite melt contamination. A significant part of xenoliths demonstrates a positive Eu anomaly, which indicates the influence of subducted crust component at one of the stages of xenolith modification.