Partitioning of potassium between iron and silicate at the core-mantle boundary

Naohisa Hirao, Eiji Otani, Tadashi Kondo, Noriaki Endo, Toshiko Kuba, Toshiaki Suzuki, Takumi Kikegawa

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Abstract

Chemical reactions and the partitioning of potassium between metallic iron and potassium-silicate were studied at the core-mantle boundary (CMB) condition, 2900 km deep in the Earth, in a laser-heated diamond-anvil cell (LHDAC). Analytical transmission electron microscope (ATEM) analysis of the recovered samples from 134 GPa and 3500 K, prepared with Focused Ion Beam (FIB) techniques, revealed significant dissolution of potassium (0.8 wt.%) into molten iron, indicating that the partition coefficient of potassium between iron and silicate is 0.15. Our results show that the Earth's core can contain 35 ppm total potassium, i.e., 4.1 × 10-3 PPM of 40K, which could serve as a heat source corresponding to 0.23 TW in the Earth's core.

Original languageEnglish
Article numberL08303
JournalGeophysical Research Letters
Volume33
Issue number8
DOIs
Publication statusPublished - 2006 Apr 28

ASJC Scopus subject areas

  • Geophysics
  • Earth and Planetary Sciences(all)

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    Hirao, N., Otani, E., Kondo, T., Endo, N., Kuba, T., Suzuki, T., & Kikegawa, T. (2006). Partitioning of potassium between iron and silicate at the core-mantle boundary. Geophysical Research Letters, 33(8), [L08303]. https://doi.org/10.1029/2005GL025324