Grain boundary diffusion cannot explain the W isotope heterogeneities of the deep mantle

YH Peng and T Yoshino and J Deng, NATURE COMMUNICATIONS, 16, 1866 (2025).

DOI: 10.1038/s41467-025-57120-1

The low 182W/184W and high 3He/4He in some ocean island basalts compared to the bulk mantle values may derive from the Earth's core through long- term core-mantle interactions. It has been proposed that the grain boundary diffusion of siderophile elements is an efficient mechanism for core-mantle interaction and may effectively modify the W isotopic compositions of the plume-source mantle. In this study, we perform large-scale molecular dynamics simulations driven by machine learning potentials of ab initio quality to investigate the diffusion of W along ferropericlase grain boundaries and in (Mg,Fe)O liquid. Here we show that the diffusion of W is sluggish under core-mantle boundary conditions, and thus is unlikely to have observable impacts on the W isotopic compositions of terrestrial igneous rocks.

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