Equation of state of Al-bearing perovskite to lower mantle pressure conditions

被引:40
作者
Daniel, I
Cardon, H
Fiquet, G
Guyot, F
Mezouar, M
机构
[1] Univ Lyon 1, ENS Lyon, CNRS, UMR 5570,Lab Sci Terre, F-69622 Villeurbanne, France
[2] Univ Paris 06, Lab Mineral Cristallog, UMR 7590, CNRS, F-75252 Paris 05, France
[3] European Synchrotron Radiat Facil, F-38043 Grenoble, France
关键词
D O I
10.1029/2001GL013011
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
Al2O3 is estimated to total 4 to 5 mol% in all mantle compositional models, and is believed to be incorporated into (Mg,Fe)SiO3-perovskite at lower mantle conditions. Using synchrotron X-ray diffraction, we have measured the 300 K equation of state of a perovskite with X-Al = Al/(Al+Mg+Si) = .077, up to 32 GPa. A least squares refinement of two independent data sets yields the following 3 equation of state parameters V-0 = 163.52(3) Angstrom (3), K-0 = 229(4) GPa, and K-0 = 2.5(4). These values allow us to assess the most probable substitution mechanism for aluminium into perovskite at pressure conditions of the shallow lower mantle. Al3+ is likely to be incorporated in place of Si4+ in the octahedral site of perovskite, hence requiring the creation of oxygen vacancies for charge balance. As a consequence, aluminous perovskites may have a high affinity for water. The enhanced compressibility of aluminous perovskite certainly has also strong geophysical and geochemical implications, as it may revive perovskite-rich lower mantle models.
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页码:3789 / 3792
页数:4
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