摘要：AbstractThe temperature dependence of the Al2O3solubility in bridgmanite has been determined in the system MgSiO3–Al2O3at temperatures of 2750–3000 K under a constant pressure of 27 GPa using a multi-anvil apparatus. Bridgmanite becomes more aluminous with increasing temperatures. A LiNbO3-type phase with a pyrope composition (Mg3Al2Si3O12) forms at 2850 K, which is regarded as to be transformed from bridgmanite upon decompression. This phase contains 30 mol% Al2O3at 3000 K. The MgSiO3solubility in corundum also increases with temperatures, reaching 52 mol% at 3000 K. Molar volumes of the hypothetical Al2O3bridgmanite and MgSiO3corundum are constrained to be 25.95 ± 0.05 and 26.24 ± 0.06 cm3/mol, respectively, and interaction parameters of non-ideality for these two phases are 5.6 ± 0.5 and 2.2 ± 0.5 KJ/mol, respectively. The increases in Al2O3and MgSiO3contents, respectively, in bridgmanite and corundum are caused by a larger entropy of Al2O3bridgmanite plus MgSiO3corundum than that of MgSiO3bridgmanite plus Al2O3corundum with temperature, in addition to the configuration entropy. Our study may help explain dynamics of the top lower mantle and constrain pressure and temperature conditions of shocked meteorites.Graphical abstractDisplay OmittedHighlights•Phase relations in the system MgSiO3–Al2O3were determined up to 3000 K at 27 GPa.•Bridgmanite can contain 30 mol% Al2O3at 27 GPa and 3000 K.•The solubility of Al2O3in bridgmanite and that MgSiO3in corundum increase with temperatures.•We constrain the molar volume and non-ideality of Al2O3bridgmanite and MgSiO3corundum.•Temperature dependence of Al2O3solubility in bridgmanite may explain the dynamics of the top lower mantle.
