GEOCHEMICAL IDENTIFICATION OF GRANULITES IN XENOLITHS FROM YAKUTIAN KIMBERLITES

Abstract

Newly obtained data (ICP-MS, XRF, and atomic absorption analyses) are reported for a broad spectrum of REE in xenoliths of metabasite granulites (mafic crystalline schists), charnockites, and metapyroxenites from the kimberlite pipes Obnazhennaya, Slyudyanka (northeastern Siberian Platform), and Udachnaya (central Siberian Platform). The geochemistry of the pristine rocks suggests that the granulites from the Obnazhennaya and Slyudyanka pipes represent a cumulative magmatic series with geochemical signatures of tholeiites from modern island arcs. The mafic granulites from the Udachnaya pipe are metamorphosed volcanics with geochemical characteristics of E-MORB and oceanic-island tholeiites. The lower crustal evolution of the central Siberian Platform was generally similar to that of the Anabar and Aldan shields. The data presented in the paper testify that the evolution was different in the northeastern and central geoblocks of the platform, and these geoblocks should have belonged to different terranes.