'Domestic' origin of opaque assemblages in refractory inclusions in meteorites

Abstract

Experimental studies indicate that opaque assemblages rich in refractory siderophile elements were formed within host calcium- and aluminium-rich inclusions (CAIs) by exsolution, oxidation and sulphidization of homogeneous alloys, rather than by aggregation of materials in the solar nebula before the formation of CAIs. These opaque assemblages are thus not the oldest known solid materials, as was once thought, and they do not constrain processes in the early solar nebula before CAI formation. Instead, the assemblages record the changing oxygen fugacity experienced by CAIs during slow cooling in nebular and/or planetary environments.