Carbon chemistry in pyrolite melt

Updated: Feb 19, 2019

Understanding the forms in which carbon existed in the molten early Earth is a critical step towards quantifying the carbon budget of Earth's deep interior. We employ first-principles molecular dynamics to study the evolution of carbon species as a function of pressure and temperature in a molten carbon-bearing Bulk Silicate Earth composition at 3000-5000 K. We find a wide range of carbon coordination environments, which depend strongly on the pressure, temperature and oxidation state of the melt. At low pressures, carbon is predominantly in the form of unpolymerized carbon, while at mid-mantle pressures, carbon becomes increasingly polymerized, forming complex clusters with iron and silicon.