Structural evolution in a pyrolitic magma ocean under mantle conditions

Structure and properties of terrestrial magma oceans control the co-evolution core, mantle atmosphere early Earth, but are poorly understood because discrepancies remain between experiments theoretical calculations. Here we combine acoustic velocity measurements ab initio simulations on pyrolite glass/melt with a silicate Earth-like composition. In complex system, find gradual increase sound increasing pressure. Through simulations, this is explicable by transition from four- to six-fold coordinated Si occurring over entire regime. These results at odds recent X-ray diffraction measurements, which show an abrupt change in Si-O coordination 35 GPa. It however consistent high-pressure data, where Ni partitioning molten metal exhibits similar Unlike amorphous silica, smooth structural evolution multicomponent system implies progressive changes ocean depth, such as density, element transport properties, which, when incorporated into models, may improve our understanding history Earth other rocky planets.