TY  - JOUR
A1  - Liu, Zhaodong
A1  - McCammon, Catherine
A1  - Wang, Biao
A1  - Dubrovinsky, Leonid
A1  - Ishii, Takayuki
A1  - Bondar, Dmitry
A1  - Nakajima, Ayano
A1  - Tange, Yoshinori
A1  - Higo, Yuji
A1  - Cui, Tian
A1  - Liu, Bingbing
A1  - Katsura, Tomoo
T1  - Stability and Solubility of the FeAlO3 Component in Bridgmanite at Uppermost Lower Mantle Conditions
Y1  - 2020
VL  - 125
IS  - 2
JF  - Journal of Geophysical Research: Solid Earth
DO  - 10.1029/2019JB018447
DO  - 10.23689/fidgeo-4690
N2  - We report the stability and solubility of the FeAlO3 component in bridgmanite based on phase relations in the system MgSiO3-FeAlO3 at 27 GPa and 2000 K using a multi-anvil apparatus combined with in situ synchrotron X-ray diffraction measurements. The results demonstrate that the FeAlO3 component dominates Fe3+ and Al3+ substitution in bridgmanite, although trace amounts of oxygen- and Mg-site vacancy components are also present. Bridgmanite with more than 40 mol% FeAlO3 transforms into the LiNbO3-type phase upon decompression. The FeAlO3 end-member decomposes into corundum and hematite and does not form single-phase bridgmanite. We determined the maximum solubility of the FeAlO3 component in bridgmanite at 27 GPa and 2000 K to be 67 mol%, which is significantly higher than previously reported values (25–36 mol%). We determined the partial molar volume (27.9 mol/cm3) and bulk modulus (197 GPa) of hypothetical FeAlO3 bridgmanite, which are significantly higher and lower than those of AlAlO3 and FeSiO3 bridgmanite, respectively. The non-ideality of MgSiO3-FeAlO3 solid solution (W = 13 kJ/mol, where W is the interaction parameter) is significantly larger than that for MgSiO3-AlAlO3 (5 kJ/mol) and MgSiO3-FeSiO3 (3 kJ/mol) solid solutions. The rapid decrease in abundance of the MgAlO2.5 component in bridgmanite with increasing pressure is enhanced by the presence of the FeAlO3 component. The FeAlO3 content in pyrolite and mid-ocean ridge basalt is far below its solubility limit in bridgmanite and provides new insight into the mineralogy of the lower mantle.
UR  - http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/9036
ER  -