A year in the life of an aluminous metapelite xenolith-The role of heating rates, reaction overstep, H2O retention and melt loss

► Zoned metapelitic xenoliths are consistent with single stage equilibrium evolution. ► Heating rates govern the degree of retention of H2O in lower grade hydrates. ► Stability of solid phases, particularly corundum, is sensitive to bulk H2O contents.