Elasticity of (Mg,Fe)O through the spin transition of iron in the lower mantle

J. C. Crowhurst*, J. M. Brown, A. F. Goncharov, S. D. Jacobsen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

139 Scopus citations

Abstract

Changes in the electronic configuration of iron at high pressures toward a spin-paired state within host minerals ferropericlase and silicate perovskite may directly influence the seismic velocity structure of Earth's lower mantle. We measured the complete elastic tensor of ferropericlase, (Mg 1-x,Fex)O (x = 0.06), through the spin transition of iron, whereupon the elastic moduli exhibited up to 25% softening over an extended pressure range from 40 to 60 gigapascals. These results are fully consistent with a simple thermodynamic description of the transition. Examination of previous compression data shows that the magnitude of softening increases with iron content up to at least x = 0.20. Although the spin transition in (Mg,Fe)O is too broad to produce an abrupt seismic discontinuity in the lower mantle, the transition will produce a correlated negative anomaly for both compressional and shear velocities that extends throughout most, if not all, of the lower mantle.

Original languageEnglish (US)
Pages (from-to)451-453
Number of pages3
JournalScience
Volume319
Issue number5862
DOIs
StatePublished - Jan 25 2008

ASJC Scopus subject areas

  • General

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