Causes and consequences of outer core stratification

George Helffrich, Satoshi Kaneshima

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)


The Earth's outer core appears to be compositionally layered. Exotic mechanisms such as an original chemically layered core preserved from the Earth's accretionary period, or compositionally different core material delivered by a Moon-creating impactor are conceivable, but require a core whose outermost part has been stratified throughout core history, relying on unknowable processes to achieve. Barodiffusion and core-mantle reaction lead to layers significantly thinner than observed. We show that a balance of mass transferred from the inner core to the top of the outer core is possible, and that the stratification could arise as a byproduct of light element accumulation. However, if a subadiabatic thermal gradient at the top of the outer core exists that quells radial flow, it could serve as a witness of light element accumulation by preventing mixing with the convecting part of the core. The temperature difference through a subadiabatic layer could be 80-300. K and carry heat fluxes through the core-mantle boundary of 0.5-23 TW, given uncertainty in core properties.

Original languageEnglish
Pages (from-to)2-7
Number of pages6
JournalPhysics of the Earth and Planetary Interiors
Publication statusPublished - Oct 2013

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Geophysics
  • Physics and Astronomy (miscellaneous)
  • Space and Planetary Science


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