Insufficient Energy From MgO Exsolution to Power Early Geodynamo

Zhixue Du, Colin Jackson, Neil Bennett, Peter Driscoll, Jie Deng, Kanani K.M. Lee, Eran Greenberg, Vitali B. Prakapenka, Yingwei Fei

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

The origin of Earth's ancient magnetic field is an outstanding problem. It has recently been proposed that exsolution of MgO from the core may provide sufficient energy to drive an early geodynamo. Here we present new experiments on Mg partitioning between iron-rich liquids and silicate/oxide melts. Our results indicate that Mg partitioning depends strongly on the oxygen content in the iron-rich liquid, in contrast to previous findings that it depends only on temperature. Consequently, MgO exsolution during core cooling is drastically reduced and insufficient to drive an early geodynamo alone. Using the new experimental data, our thermal model predicts inner core nucleation at ~850 Ma and a nearly constant paleointensity.

Original languageEnglish (US)
Pages (from-to)11,376-11,381
JournalGeophysical Research Letters
Volume44
Issue number22
DOIs
StatePublished - Nov 28 2017
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences

Keywords

  • core dynamo
  • elemental partitioning
  • high pressure
  • laser-heated diamond anvil cell
  • magnetic field
  • paleomagnetism

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