Causes and consequences of outer core stratification

George Helffrich, Satoshi Kaneshima

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

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
Volume223
DOIs
Publication statusPublished - Oct 1 2013

Fingerprint

outer core
stratification
causes
radial flow
core-mantle boundary
inner core
Moon
heat flux
mantle
light elements
history
temperature
impactors
moon
temperature gradients
Earth mantle
histories

All Science Journal Classification (ASJC) codes

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

Cite this

Causes and consequences of outer core stratification. / Helffrich, George; Kaneshima, Satoshi.

In: Physics of the Earth and Planetary Interiors, Vol. 223, 01.10.2013, p. 2-7.

Research output: Contribution to journalArticle

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