Experimental Study of Diamond Crystallization in Carbonate-Peridotite Melts at 8.5 GPa

摘要

The composition of the parental melt for the predominant mass of natural diamonds may be determined from concerted mineralogical and experimental data [1]. The study of mineral inclusions in diamonds demonstrates their affiliation to peridotite and eclogite parageneses [2]; i.e., the composition of the diamond crystallization medium is strongly variable. Its component composition may be estimated from inclusions of minerals, quenched melts, and fluids in diamonds. It has become evident that the multicomponent and multiphase parental medium consists of chemically different compounds and phases: oxides, silicates, alumino-silicates, sulfides, phosphates, carbonates, chlorides, metals, water, carbon dioxide, and others. However, the main problem of dominating compound in parental media during the diamond formation is still unclear. The reason is that efficiency of diamond formation for mantle materials, including those primarily included in diamonds, is not evident and cannot be reliably determined from mineralogical data. That is why the chemical mode of diamond formation in mantle matter cannot be revealed.