Melting experiment on a model chondritic mantle composition at 25 GPa

Abstract

We have conducted melting experiments on a chondritic mantle composition in the five‐component system CaO‐FeO‐MgO‐Al 2 O 3 ‐SiO 2 at 25 GPa. The liquidus phase at this pressure is majorite garnet, and the second crystallizing phase is Mg‐silicate perovskite or magnesiowustite; these phases seem to be consumed into the melt at almost the same temperature. The present experiments indicate that majorite garnet fractionation might have occurred in the chondritic primitive mantle, if the partial molten zone extended to a depth equivalent to the upper part of the lower mantle in the early stages of terrestrial evolution.