Fig. 2: Geochemical signature of magma ocean solidification for an intermediate (δ = 10 × 10−3) phase separation efficiency.
From: Solidification of Earth’s mantle led inevitably to a basal magma ocean
a–c, Snapshots at the final stage of the simulations showing the distribution of various geochemical ratios (normalized to their ratio in the BSE) across the mantle Lu/Hf (a), Hf/W (b) and Sm/Nd (c). Sm/Nd and Hf/W ratios are always larger than 1 in solids and lower than 1 in residual melts. By contrast, Lu/Hf behaves similarly at low pressure (olivine–melt fractionation) but becomes less than 1 in solids and greater than 1 in residual melts at high pressures (bridgmanite–melt fractionation). The geochemical signature of both low-pressure and high-pressure fractionation (Lu/Hf ratio) as well as enriched solids and depleted liquids (Sm/Nd and Hf/W ratios) are preserved in the early solid mantle after magma ocean solidification. These are then expected to be further stirred by ensuing thermochemical convection in the solid mantle throughout Earth’s subsequent history. See Supplementary Figs. 6 and 7 for more extreme cases.
