Intergranular diamonds derived from partial melting of crustal rocks at ultrahigh‐pressure metamorphic conditions

Abstract

Abstract By reporting for the first time intergranular diamond in quartz–feldspar (Qtz–Kfs) aggregates, the processes of metamorphic diamond formation have to be reconsidered. Based on their Kfs/Qtz ratio, the texture of these aggregates are proposed to result from ‘granitic’ melt with a calculated composition that corresponds well with that of experimental data for the pelitic system. Taking into account experiments on CO 2 solubility in silicate melt under ultrahigh‐pressure conditions, a granitic melt is further suggested to act as a crystallization medium as well as a transport medium for producing metamorphic diamond.