Elasticity of (Mg,Fe)O Through the Spin Transition of Iron in the Lower Mantle
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- J. C. Crowhurst
- Chemistry, Materials, and Life Sciences Directorate, Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA.
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- J. M. Brown
- Chemistry, Materials, and Life Sciences Directorate, Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA.
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- A. F. Goncharov
- Chemistry, Materials, and Life Sciences Directorate, Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA.
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- S. D. Jacobsen
- Chemistry, Materials, and Life Sciences Directorate, Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA.
書誌事項
- 公開日
- 2008-01-25
- DOI
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- 10.1126/science.1149606
- 公開者
- American Association for the Advancement of Science (AAAS)
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説明
<jats:p> 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 <jats:sub> 1– <jats:italic>x</jats:italic> </jats:sub> ,Fe <jats:sub> <jats:italic>x</jats:italic> </jats:sub> )O ( <jats:italic>x</jats:italic> = 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 <jats:italic>x</jats:italic> = 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. </jats:p>
収録刊行物
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- Science
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Science 319 (5862), 451-453, 2008-01-25
American Association for the Advancement of Science (AAAS)
