Journal ArticleDOI
Fundamental thermodynamic relations and silicate melting with implications for the constitution of D
TLDR
In this article, the authors describe fundamental thermodynamic relations (Helmholtz free energy as a function of volume and temperature) for solids and liquids, simple physically based expressions which contain all thermodynamic information about a system.Abstract:
We describe fundamental thermodynamic relations (Helmholtz free energy as a function of volume and temperature) for solids and liquids, simple physically based expressions which contain all thermodynamic information about a system. The solid fundamental relation consists of Debye and Birch-Murnaghan finite-strain theory combined in the Mie-Gruneisen framework. The liquid fundamental relation is derived by taking the high-temperature limit of the solid expression. We derive the liquid equation of state, which contains only four parameters, from the liquid fundamental relation and show that it successfully describes measurements of liquid alkali metals, water, and liquid diopside over a wide range of pressure and temperature. We find optimal fundamental relation parameters for diopside, enstatite, ilmenite, and perovskite and find the solid relation to be in excellent agreement with data, including heat capacities, thermal expansion, and MgSiO3 phase equilibria. We then combine the liquid and solid fundamental relations to calculate the melting curves of diopside, enstatite, and perovskite, which are found to be in excellent agreement with experiment. All predicted melting curves have dT/dP slopes which decrease steadily with pressure, eventually becoming negative because of liquid-crystal density inversion. Our predicted melting temperature of perovskite in the D″ region (3750 K) at the base of the mantle is thousands of degrees lower than previous estimates, yet it is consistent with experimental data. The predicted melting curve, although consistent with the lack of widespread melting in the lower mantle, is much lower than recently proposed geotherms in the D″ layer at the base of the mantle. By combining our results with seismic observations of the deep mantle, we propose that the D″ layer consists of magnesiowustite and silica in the form of stishovite or its recently discovered high-pressure modification.read more
Citations
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Thermodynamics of mantle minerals - II. Phase equilibria
TL;DR: In this paper, a thermodynamic method for the computation of phase equilibria and physical properties of multiphase assemblages is presented, and a global inversion strategy for determining the values of the free parameters in their theory and compare inverted parameter values with expectations based on scaling arguments.
Journal ArticleDOI
Thermodynamics of mantle minerals – I. Physical properties
TL;DR: In this article, a theory for the computation of phase equilibria and physical properties of multicomponent assemblages relevant to the mantle of the Earth is presented, which is based on the concept of fundamental thermodynamic relations appropriately generalized to anisotropic strain and encompassing elasticity in addition to the usual isotropic thermodynamic properties.
Journal ArticleDOI
The solubility of quartz in H2O in the lower crust and upper mantle
TL;DR: In this article, the authors derived the equilibrium constant of the reaction quartz = SiO2(aq)log K = 4.2620 −5764.2T + 1.7513 × 106T2−2.2869 × 108T3 + [2.8454−1006.9T + 3.5689 × 105T2] log ρH2O where logK = logmSiO 2(aq).
Journal ArticleDOI
Petrology, elasticity, and composition of the mantle transition zone
Joel Ita,Lars Stixrude +1 more
TL;DR: In this paper, the authors compare the predictions of compositional models of the mantle transition zone to observed seismic properties by constructing phase diagrams in the MgO-FeO-CaO-Al2O3-SiO2 system and estimating the elasticity of the relevant minerals.
Journal ArticleDOI
Compositional heterogeneity in the bottom 1000 kilometers of earth's mantle : Toward a hybrid convection model
TL;DR: A range of geophysical evidence indicates that compositionally distinct mantle domains may exist in the bottom 1000 kilometers of the mantle, which implies that mantle convection is more complex than envisaged by conventional end-member flow models.
References
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Preliminary reference earth model
TL;DR: In this paper, a large data set consisting of about 1000 normal mode periods, 500 summary travel time observations, 100 normal mode Q values, mass and moment of inertia have been inverted to obtain the radial distribution of elastic properties, Q values and density in the Earth's interior.
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Finite strain isotherm and velocities for single-crystal and polycrystalline NaCl at high pressures and 300°K
TL;DR: In this article, a large portion of the data is consistent, to within reasonable uncertainties, with the Eulerian formulation of finite strain, in the BE2 form, which contains three parameters, of which two, K0 and K0′, are obtainable from single-crystal ultrasonic measurements, while the third, K 0″, may be found with the aid of shock wave data.
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Elasticity and constitution of the Earth's interior
TL;DR: In this paper, the authors derived a general equation for the variation of the quantity,, in a homogeneous gravitating layer with an arbitrary gradient of temperature, and discussed the parameters of this equation in terms of the experimental and theoretical relations for solids.