Remarks on depleted mantle evolution models used for Nd model age calculation

Abstract

This paper reviews published models on Nd isotopic evolution of the upper mantle, and focusses in particular on the problems of models currently in use for Nd model age (T Nd ) calculation and should help to prevent misleading T Nd interpretation. Presently, T Nd calculations are generally based on depleted mantle (DM) evolutionary models (T DM ), implying that continental crust is generated from suboceanic, convecting mantle. However, the properties of the secular evolution curve of the DM, are rather controversial. Depending on the models used, differences between calculated T DM ages for a given sample may be as much as a few hundred millions years