Selective transport of primordial signatures across the core-mantle boundary by adsorption

The anti-correlation between the ³ He/ ⁴ He and ¹⁸² W/ ¹⁸⁴ W ratios observed in some ocean island basalts suggests possible core contributions to the plume source. However, the mechanism by which He and W are transported across the core-mantle boundary remains elusive. Here, we combine high-pressure experiments and large-scale atomistic simulations to assess element transport from the core to the mantle via oxide exsolution. We find that adsorption can effectively operate at ultra-high temperatures under planetary core conditions. Ferropericlase nanoparticles can selectively adsorb W but not Pt, suggesting that W may be fractionated from highly siderophile elements by oxide exsolution. The adsorption mechanism may imprint core-like isotopic signatures onto ocean island basalts and potentially affect the Earth’s deep geochemical cycles.