LATE PAN-AFRICAN GRANITOIDS FROM THE GROVE MOUNTAINS, EAST ANTARCTICA: AGE, ORIGIN AND TECTONIC IMPLICATIONS

Abstract

The Grove Mountains of East Antarctica are an inland continuation of the Pan-African Prydz Belt. The area is made up of high-grade metamorphic complex and numerous intrusive granitoid bodies including foliated charnockite, sheeted granite and charnockitic and granitic dykes. U–Pb zircon dating reveals that the charnockite, charnockitic dyke, granite and granitic dyke were emplaced in succession during the period from 550 to 500 Ma. Trace element abundances indicate that all the granitoids are of A-type affinity, characterized by enrichment in REE, Y, Ba, Sr, Ga and HFS elements (Zr, Nb, Th). Sr–Nd isotopic analyses yielded high initial ⁸⁷Sr/⁸⁶Sr ratios (0.7095–0.7156) and low ɛNd(T) values (−9.2 to −13.4). Depleted mantle-based Nd model ages range from 2.0 to 2.3 Ga. These geochemical and isotopic signatures point to their ultimate derivation from a long-term enriched subcontinental lithospheric mantle.