Abstract

High-pressure experimental studies make it possible to determine the completely miscible silicate-carbonate melts with dissolved carbon as the parental media for diamonds. Physico-chemically the genesis of diamonds and associated phases is unraveled in the mantle-carbonatite theory. Its effectivity is illustrated with the experimental study at 6GPa of the diamond-forming system peridotite/eclogite-carbonate-(C-O-H-fluid). This research has resulted in the discovery of the peritectic reaction of olivine and jadeite-bearing melts with formation of garnet. Only this reaction provides an ultrabasic-basic evolution of the melts with transfer from the diamond-bearing peridotites to eclogites (in conditions of the melts fractional crystallization under the Earth’s gravitation field). The mantle-carbonatite theory will also allow an understanding of the genesis of the unique Matryoshka-type diamond that is of interest as the diamond-host having a closed empty cavity inside of which the movable diamond-inclusion is revealed.

Keywords:Diamond origin; Mantle-carbonatite theory; Ultrabasic-basic evolution; Olivine peritectic reaction; Metastable graphite; Origin on unique Matryoshka-type diamond