The age and evolution of the lithospheric mantle in the East Antarctic Craton: osmium isotope composition and the distribution of the platinum group elements in spinel lherzolite nodules

Abstract

The mantle xenoliths of lherzolite composition from Mesozoic alkaline-ultrabasic diatremes of the Jetty Oasis were studied. The studied xenoliths represent the mantle section of the East Antarctic Craton down to depths of 60-80 km. The osmium isotope composition of these nodules testifies to the beginning of the formation of the lithospheric mantle in the considered region at about 2400 Ma. The absence of any signs of Early Archean lithosphere points either to partial destruction of the lithosphere at the convergent boundary of the plates in the Late Archean or to thermal erosion of the Archean lithosphere under the deep-seated plume impact at the Mesozoic time during rift propagation.