Elastic Shear Anisotropy of Ferropericlase in Earth's Lower Mantle

+ See all authors and affiliations

Science  10 Apr 2009:
Vol. 324, Issue 5924, pp. 224-226
DOI: 10.1126/science.1169365

You are currently viewing the abstract.

View Full Text


Seismic shear anisotropy in the lowermost mantle most likely results from elastic shear anisotropy and lattice preferred orientation of its constituent minerals, including perovskite, post-perovskite, and ferropericlase. Measurements of the elastic shear anisotropy of single-crystal (Mg0.9Fe0.1)O up to 69 gigapascals (GPa) show that it increased considerably across the pressure-induced spin transition of iron between 40 and 60 GPa. Increasing iron content further enhances the anisotropy. This leads to at least 50% stronger elastic shear anisotropy of (Mg,Fe)O in the lowermost mantle compared to MgO, which is typically used in geodynamic modeling. Our results imply that ferropericlase is the dominant cause of seismic shear anisotropy in the lower mantle.

    View Full Text