Investigating the Density of a Chondritic Melt Under High Pressure, and Implications for Earth Formation

Determining how the Earth's initial magma ocean crystalised into a solid body is important for understanding Earth's evolution to its present-day state. One of the fundamental properties governing the crystalisation of the magma ocean is the relative density between the crystalizing minerals and the melt phase. This is because the relative densities control whether melts float or sink, and whether, for instance, an isolated basal magma ocean form. However, the composition of the melt phase continually changes as crystallization occurs, particularly for the final melts which are very different from the initial melt. As such the density of melts are needed over a much wider range of compositions than the solid phases. One of the difficulties with predicting densities at any compositions is that normal equations of state such as the Birch-Murnagham are difficult to extend to arbitrary composition. Furthermore, there is limited experimental data for these melt compositions, due to experimental difficulties when working with a liquid sample. As such, my project will obtain thermodynamic data from ab initio calculations, then using machine learning this data will be fitted, to produce a model that can describe the density, for any given pressure, temperature, and composition within the space of the magma ocean.