Equation of state parameters given by Zhang & Weidner (1999) are taken as an alternative extreme set for AlPv (dot-dashed line). We have developed a comprehensive model based on the radial variations of shear velocity in the D″ layer (the base of the lower mantle) and the high-P,T elastic properties of major candidate minerals, including the effects of post-perovskite phase changes. Second, we analyse the influence of uncertainties in the bulk modulus of AlPv. Shaded areas depict their a priori and a posteriori uncertainties (light and dark grey shading). The P–V–T measurements are taken from Fiquet et. Fei Y. 3, we compare the a priori and a posteriori uncertainties assuming an iron partitioning equal to 1. The latter indicates that some subducting slabs penetrate deep into the mantle (e.g. The minimization is performed iteratively using standard procedures (for details see Tarantola & Valette 1982). This additional heating is consistent with the assumption of existence of basalt in which radioactive elements are concentrated at the base of the mantle. The temperature derivative of the shear velocity for ppv is reported to be (1995) and McDonough & Sun (1995) put the missing silicon budget into the core whereas Ringwood (1979) suggested that Si was volatilized during Earth accretion. In these cases, the inverted composition appears to be homogeneous throughout the mantle (except for the peculiar iron behaviour as already mentioned). This article is a PNAS Direct Submission. (A) Cross-section of the Earth. Fig. Dewaele et. Two recent studies on CaSiO3 perovskite based on X-ray diffraction measurements (Wang et. In contrast, models with a double-crossing phase transition cannot match the seismological observations. 2B), the shear wave velocity therefore has an “S-shaped” depth dependence, which is consistent with the model observed beneath the western Pacific (Fig. Nevertheless, no clear consensus has emerged from these studies: Vacher et. These three parameter sets will be used to study the influence of uncertainties on elastic parameters of MgPv by random sampling of (∂K0,T/∂T)P and α within these 2σ ellipses. The corresponding partition coefficient, To cover this large experimental range, we choose two characteristic values of, We use the Birch–Murnaghan equation of state (third order) to relate pressure, Temperature derivatives of elastic moduli of MgSiO, Rare gas systematics: formation of the atmosphere evolution and structure of the mantle, Transition region of the Earth's upper mantle, Shifts in thermal expansivity with Fe content for solid solutions of MgSiO, Evaluation of (Mg,Fe) partitioning between silicate perovskite and magnesiowustite up to 120 GPa and 2300 K, Equation of state of lower mantle (Al,Fe)-MgSiO, Iron partitioning in Earth's mantle: toward a deep lower mantle discontinuity, Elastic properties from acoustic and volume compression experiments, Constraints on lower mantle composition and temperature from density and bulk sound velocity profiles, Pressure-induced changes in the compression mechanism of aluminous perovskite in the Earth's mantle, Thermodynamic parameters in the Earth as determined from seismic profiles, Thermodynamically consistent decompression: implications for the lower mantle composition, Layered convection with an interface at a depth of 1000 km: stability and generation of slab-like downwellings, Geochemical observations and one layer mantle convection, The composition and geotherm of the lower mantle: constraints from the elasticity of silicate perovskite, Equation of state of Al-bearing perovskite to lower mantle pressure conditions, Effects of aluminum on the compressibility of silicate perovskite, Thermal convection in a heterogeneous mantle, Towards a lower mantle reference temperature and composition, P-V-T equation of state of periclase from synchrotron radiation experiments, Effects of temperature and composition on the bulk modulus of (Mg,Fe)O, Experimental determination of element partitioning and calculation of phase relations in the MgO-FeO-SiO, Mixing properties in the Earth's mantle: effects of the viscosity stratification and of oceanic crust segregation, High-temperature thermal expansion of lime periclase corundum and spinel, Thermoelastic properties and crystal structure of MgSiO, Global seismic tomography a snapshot of convection in the Earth, Mineral assemblages in a model mantle composition, Systematic variation of bulk modulus of wustite with stoichiometry, The fate of subducted basaltic crust in the Earth's lower mantle, Mantle geochemistry: the message from oceanic volcanism, Absence of an aluminous phase in the upper part of the Earth's mantle, An experimental study of the garnet-perovskite transformation in the system MgSiO, Measured elastic moduli of single-crystal MgO up to 1800 K, Calculated elastic and thermal properties of MgO at high pressures and temperatures, Petrology elasticity and composition of the mantle transition zone, A temperature profile of the mantle transition zone, Elasticity composition and temperature of the Earth's lower mantle: a reappraisal, The elasticity of periclase to 3 GPa and some geophysical implications, Elasticity shear-mode softening and high-pressure polymorphism of wustite (Fe, Structure and elasticity of single-crystal (Mg,Fe)O and a new method of generating shear waves for gigahertz ultrasonic interferometry, The integral enstatite chondrite model of the Earth, Density and composition of the lower mantle, Importance of anelasticity in the interpretation of seismic tomography, First-principles determination of elastic properties of CaSiO, Determination of Fe—Mg partitioning between perovskite and magnesiowustite, Compositional stratification in the deep mantle, Constraints on seismic velocities in the Earth from traveltimes, Mineralogy and dynamics of a pyrolite lower mantle, Synthesis and equation of state of (Mg,Fe)SiO, The core-mantle boundary layer and deep Earth dynamics, Bulk moduli of wustite and periclase: a comparative study, Effect of pressure temperature and composition on lattice parameters and density of (Fe,Mg)SiO, Multivariable dependence of Fe-Mg partitioning in the lower mantle, Microstructures and iron partitioning in (Mg,Fe)SiO, Constraints on the lower mantle composition from molecular dynamics simulations of MgSiO. The geotherm in the deep Earth has often been evaluated based on the P,T conditions of major phase transitions expected in the mantle and core such as the olivine-spinel and spinel-perovskite transitions and the melting of iron alloy. (2004) suggested radially heterogeneous lower mantle models. S1b). A single-crossing phase transition model was found to be more favorable in reproducing the observed seismic wave velocity structure than a double-crossing phase transition model. al. Depth dependence of inverted molar fractions of individual end-members: MgSiO3 perovskite (MgPv), FeSiO3 perovskite (FePv), Al2O3 perovskite (AlPv), CaSiO3 perovskite (CaPv), periclase (MgMw) and wustite (FeMw). Therefore, the reported large velocity reduction, if substantiated by further observations could be interpreted as a double-crossing phase transition due to a local temperature increase of a few hundred Kelvin which can be produced by the decay of radioactive elements. As required by our inversion, the inverted parameters match both PREM and ak135 models, within 0.5 per cent for density and within 0.1 per cent for bulk sound velocity. (∂K0,T/∂T)P is considered to be constant as a function of temperature. These two figures reveal that the resolution of all parameters is constant with depth and that density and bulk sound velocity do not put significant constraints on either the calcium or the aluminium content of the lower mantle. al. Given the uncertainties on K0,T, (∂K0,T/∂T)P (see discussion below) and intrinsic correlations, we keep K′0,T equal to 4. The values reported from separate P–V–T studies can differ significantly even though they have been obtained by matching similar observed densities.

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