REWORKING OF THE LITHOSPHERIC MANTLE OF THE SIBERIAN CRATON BY REDUCED FLUIDS IN THE MIDDLE PALEOZOIC KIMBERLITE EVENT: GEOCHEMICAL CONSEQUENCES

Abstract

Nowadays, it is commonly accepted that kimberlitic magmatism of ancient platforms was initiated by hot plumes that ascended toward the base of the continental lithosphere from the Earth’s deep-seated boundary sources such as the lower mantle/core boundary or transitional zone. The Late Devonian kimberlitic magmatism, the most productive for diamonds at the Siberian Craton, is related to the Yakutian superplume. It is suggested that the plume approaching the base of a rigid continental plate produces asthenospheric melts and related assemblages of low-Cr megacrystals. The melts replace substance of the upper asthenospheric layer and the lower lithosphere. This process is rather well studied based on geochemistry of megacrystals and high-temperature deformed peridotites from kimberlites in South Africa and Yakutia.