Terrestrial Magma Ocean Solidification and Formation of a Candidate D ′ ′ Layer

In this thesis we investigate the solidification of early magma oceans on the Earth and the formation of a deep dense layer at the core-mantle boundary. We also study the concentrations and densities of the last layers of the solidified magma ocean and how they create a deep dense layer after solid-state overturn. The deep dense layer that forms in our model matches the bulk physical properties of the D′′ layer observed by other workers. This layer is also sufficiently dense that the bulk of its material is not reentrained by the mantle after the onset of convection, and that this layer is enriched in incompatible elements such as samarium and neodymium regardless of distribution coefficients used for incompatible elements in mantle minerals such as perovskite. However, we found that this probable D′′ layer is more enriched in samarium than is to be expected for a planet’s mantle which evolves from an initially chondritic composition. Thesis Supervisor: Linda T. Elkins-Tanton Title: Assistant Professor