Phase equilibria constraints on the melt fertility of crustal rocks: The effect of subsolidus water loss

Abstract

During regional prograde metamorphism, H2O generated by ongoing dehydration reactions is likely to be continuously lost from a rock by compaction. Classical melting experiments cannot easily simulate this phenomenon, because ideally, all run products are conserved within the experimental charge, although significant equilibration and H2O generation may occur during heating. Phase equilibria modelling is used to consider the effect of subsolidus water loss (SWL) on subsequent melting relationships of felsic lithologies (including metapelite, metagreywacke and metatonalite) in the suprasolidus. SWL drives the bulk composition towards the minimum saturation point on the boundary of the wet-melt..