Survival of presolar silicon carbide grains during parent-body metamorphism: constraints on the composition of metamorphic fluids

Systematic variations in the abundances of presolar grains of Sic and diamond with petrologic type in unequilibrated ordinary chondrites (UOCs) [1,2] probably reflect differences in P-T conditions and/or fluid composition during parent-body metamorphism. It may, therefore, be possible to constrain physical conditions during the metamorphism by determining the conditions under which presolar grains are destroyed.