Influence of supercritical C-O-H-fluid on hyperbasic-basic evolution of magmatic and diamond-forming systems of the upper mantleстатьяИсследовательская статья
Аннотация:The key mechanism of ultrabasic-basic evolution of magmatic and diamond-forming melts of the upper mantle is the peritectic reaction of olivine and jadeite-containing melt with the formation of a garnet-containingassociation. The influence of increased C-O-H-fluid contents on the possibility of the peritectic olivine reaction, its temperature, the compositions of reaction phases, and the starting pointin mantle silicate-fluid magmatic olivine-jadeite–diopside – (5 wt. % C-O-H) and diamond-forming silicate - (Mg-Fe- Ca-Na-carbonate) - (7.5 wt. % C-O-N) systems was experimentally studied at 6.0 GPa and 700-1400°C. In the silicate-fluid system, the solidus and liquidus temperatures decrease, respectively, by 120 and ~60-80 °C compared to the dry silicate system. The olivine peritectic is shifted by~10 wt. % towards olivine. In the silicate-carbonate-fluid diamond-forming system, the olivine peritectic is still occurred at its temperaturedecreases by 280 °C, the solidus temperature by 380 °C in comparison with the silicate-fluid system. The CO2component carbonatizes silicates. The H2O component is released into the gas-fluid phase on the solidus, creating asupercritical hydrothermal system that coexists with solid silicates and/or carbonates.
