Effect of Pressure on the Composition of the Lower Mantle End Member Fe x O
- 1 January 1993
- journal article
- other
- Published by American Association for the Advancement of Science (AAAS) in Science
- Vol. 259 (5091) , 66-68
- https://doi.org/10.1126/science.259.5091.66
Abstract
The composition limits of FexO are sensitive to both pressure and temperature. Earlier studies have shown that FexO becomes highly nonstoichiometric when in equilibrium with metallic iron above 10 gigapascals, which is difficult to reconcile with available thermodynamic data. Experiments with a uniaxial split-sphere apparatus demonstrate that the iron content of FexO increases continuously at high pressure in excellent agreement with quantitative models and suggest that there is a discontinuity in the elastic properties of FexO above x = 0.95. On the basis of these results, it is inferred that the Earth's present lower mantle is not in equilibrium with metallic iron.Keywords
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