Carbon-bearing silicate melt at deep mantle conditions

摘要: Knowledge about the incorporation and role of carbon in silicate magmas is crucial for our understanding deep mantle processes. CO2 bearing melting its relevance upper regime have been extensively explored. Here we report first-principles molecular dynamics simulations MgSiO3 melt containing three distinct oxidation states - CO2, CO, C at conditions relevant whole mantle. Our results show that low pressures up to 15 GPa, dioxide speciation dominated by form carbonate ions. At higher pressures, dominant species are silicon-polyhedral bound carbonates, tetrahedral coordination, polymerized di-carbonates. also indicate component remains soluble high solution nearly ideal. However, elemental CO components clustering atoms hinting towards possible exsolution from reduced oxygen contents. Although lowers density, effect modest pressures. Hence, it likely above below transition zone, atop core-mantle boundary could efficiently sequester significant amounts without being gravitationally unstable.