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Deformation of polycrystalline MgO at pressures of the lower mantle
Laboratoire des sciences de la Terre, École normale supérieure de Lyon, Lyon, France
Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia, USA
Department of Earth and Planetary Science, University of California, Berkeley, California, USA
Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia, USA
Consortium for Advanced Radiation Sources, University of Chicago and Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, USA
Laboratoire des sciences de la Terre, École normale supérieure de Lyon, Lyon, France
Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia, USA
Geophysical Laboratory, Carnegie Institution of Washington, Washington, District of Columbia, USA
Room temperature investigations on the shear strength, elastic moduli, elastic anisotropy, and deformation mechanisms of MgO
(periclase) are performed in situ up to pressures of 47 GPa using radial X-ray diffraction and the diamond anvil cell. The
calculated elastic moduli are in agreement with previous Brillouin spectroscopy studies. The uniaxial stress component in
the polycrystalline MgO sample is found to increase rapidly to 8.5(±1) GPa at a pressure of 10(±1) GPa in all experiments.
Under axial compression, a strong cube texture develops which was recorded in situ. It is probable that the preferred orientation
of MgO is due to deformation by slip. A comparison between the experimental textures and results from polycrystal plasticity
suggest that the {110}
is the only significantly active slip system under very high confining pressure at room temperature. These data demonstrate
the feasibility of analyzing elastic moduli, shear strength, and deformation mechanisms under pressures relevant for the Earth's
lower mantle. Implications for the anisotropy and rheology of the lower mantle are discussed.
Published 5 November 2002.
Citation: (2002), Deformation of polycrystalline MgO at pressures of the lower mantle, J. Geophys. Res., 107(B11), 2271, doi:10.1029/2001JB000920.
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