ALKALINE-CHLORIDE COMPONENTS IN PROCESSES OF DIAMOND GROWTH IN THE MANTLE AND HIGH-PRESSURE EXPERIMENTAL CONDITIONS

Abstract

Judging from the primary fluid microinclusions [1–3], parent media of diamond formation under mantle conditions represent partial or complete multicomponent carbonate–silicate melts containing dissolved chloride, phosphate, and other components, as well as water. Their efficiency for the diamond formation was demonstrated by direct experiments at high pressures [4, 5]. These experiments revealed important aspects of diamond genesis, namely, the chemical nature and physicochemical mechanisms of diamond formation in the mantle. According to numerous thermobarometric estimates, natural diamonds are most often crystallized at 4.5–7.5 GPa and 950–1350°C [6], which corresponds to the PT region of thermodynamic stability of diamond on the phase diagram of carbon [7].