IS THERE AN ULTRADEPLETED MANTLE?

Abstract

A number of researchers have reported experimental data on the Sm-Nd isotopic system of garnet and clinopyroxene from xenoliths in the kimbcrlite pipes of southern Africa and Yakutia. In the majority of cases, they do not agree with the real values of xenolith ages and the initial 143Nd/144Nd. Consequently, they cannot be considered evidence for the existence of an ultradepleted mantle reservoir and its evolution beginning from 4.5 Ga.