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upstart writes in with an IRC submission for Bytram:

Heavy iron isotopes leaking from Earth's core:

The boundary between the liquid iron core and the rocky mantle is located some 1,800 miles (2,900 km) below Earth's surface. At this transition, the temperature drops by more than a thousand degrees from the hotter core to the cooler mantle.

The new study suggests heavier iron isotopes migrate toward lower temperatures -- and into the mantle -- while lighter iron isotopes circulate back down into the core. (Isotopes of the same element have different numbers of neutrons, giving them slightly different masses.) This effect could cause core material infiltrating the lowermost mantle to be enriched in heavy iron isotopes.

[...] Understanding the physical processes operating at the core-mantle boundary is important for interpreting seismic images of the deep mantle, as well as modeling the extent of chemical and thermal transfer between the deep Earth and surface of our planet, Lesher said.

[...] Computer simulations performed by the research team show this core material can even reach the surface, mixed with and transported by hot, upwelling mantle plumes. Some lavas erupted at oceanic hot spots such as Samoa and Hawaii are enriched in heavy iron isotopes, which Lesher and the team propose could be a signature of a leaky core.

Journal Reference:
Charles E. Lesher, Juliane Dannberg, Gry H. Barfod et al. Iron isotope fractionation at the core–mantle boundary by thermodiffusion, Nature Geoscience (DOI: doi:10.1038/s41561-020-0560-y)

Original Submission