PETROLOGICAL EVALUATION CRITERIA OF KIMBERLITE DIAMOND POTENTIAL IDENTIFIED ON THE BASIS OF THERMOXIDE BAROMETRY

DOI: 10.24411/0869-5997-2019-10027

Abstract

Petrological evaluation criteria of kimberlite rocks diamond potential based on thermoxide barometry are dis cussed. To evaluate diamond potential, oxygen barometers reflecting redox conditions in the mantle existing in the diamond stable field are used. This method is based on C:O:H ratio or calculation of equilibrium fluid composition by P-T-fo2 parameters for individual parageneses (olivine-orthopyroxene-spinel, olivine-orthopyroxene-ilmenite). Oxygen fugacity is calculated by mineral equilibrium including Fe2+–Fe3+ exchange. Calculation methods of P-T-fo2 pa rameters for pyrope, ilmenite and spinel xenocrysts are realized in PTQuick-2 software resulting in «diamond fluid area» identi- fication in C-O-H diagnostic chart.