Thermoelasticity of Silicate Perovskite and Magnesiowüstite and Stratification of the Earth's Mantle

Stixrude, Lars; Hemley, Russell J.; Fei, Yingwei; Mao, Ho‐kwang

doi:10.1126/science.257.5073.1099

Cited by 157 publications

(56 citation statements)

References 29 publications

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“…The style and efficiency of mantle convection are also strongly influenced by depth variations in the thermal conductivity [2]. Here we focus on periclase (MgO), thought to be a major constituent of Earth's deep mantle [3].…”

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confidence: 99%

Thermal Conductivity of Periclase (MgO) from First Principles

2010

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We combine first-principles calculations of forces with the direct nonequilibrium molecular dynamics method to determine the lattice thermal conductivity k of periclase (MgO) up to conditions representative of the Earth's core-mantle boundary (136 GPa, 4100 K). We predict the logarithmic density derivative a ¼ ð@ lnk=@ ln Þ T ¼ 4:6 AE 1:2 and that k ¼ 20 AE 5 Wm À1 K À1 at the core-mantle boundary, while also finding good agreement with extant experimental data at much lower pressures.

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confidence: 99%

Thermal Conductivity of Periclase (MgO) from First Principles

2010

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“…We don't really know the thermochemical reference state of the Earth [see Williams and Knittle, this volume], and many different combinations of temperature and composition are compatible with a chosen seismic reference model [Anderson, 1989;Stixrude et al, 1992;Jackson, 1998;Deschamps and Trampert, 2004]. Furthermore, both experimental and ab initio mineral physics data contain uncertainties, and there appears to be an inconsistency in the shear modulus of magnesium perovskite between experimental and ab initio data .…”

Section: Sensitivities Of Wave Speeds To Temperature and Compositionmentioning

confidence: 99%

Towards a quantitative interpretation of global seismic tomography

Trampert

Hilst

2005

Geophysical Monograph Series

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We review the success of seismic tomography in delineating spatial variations in the propagation speed of seismic waves on length scales from several hundreds to many thousands of kilometers. In most interpretations these wave speed variations are thought to reflect variations in temperature. Careful consideration of shear wave, bulk sound, and, most recently, density variations is, however, producing increasingly compelling evidence for chemical heterogeneity (that is, spatial variations in bulk major element composition) having a first-order effect on the lateral variations in mass density and elasticity of the mantle. This has profound consequences for our understanding of mantle dynamics and the thermochemical evolution of our planet. We argue that the quantitative integration of constraints from seismology, mineral physics, and geodynamics, which underlies the inference of thermochemical parameters, requires careful uncertainty analyses and should move away from emphasizing visually pleasing images and single, nonunique solutions.

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“…Discrepancies between the velocity and density jumps in spherical seismic models and estimates from experiments on phase transitions in olivine or pyro lite, as well as Earth evolution and geochemical and cosmochemical arguments have been used to advocate that there is an intrinsic chemical difference between upper and lower mantle (e.g., Stixrude et al, 1992;Khan et al, 2008;Javoy et al, 2010). If there is any chemical difference, it would need to result in a density jump at 660 km depth that is less than 6%, or else it would lead to fully layered mantle convection (Christensen and Yuen, 1984), which seismic tomography, plate evolution modeling, and considerations about the convective and thermal evolution of the Earth have shown is implausible (Silver et al, 1988;Ricard et al, 1993;Van der Hilst et al, 1997;McNamara and Van Keken, 2000).…”

Section: Density Jumpmentioning

confidence: 99%

Subduction-transition zone interaction: A review

et al. 2017

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Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTAs subducting plates reach the base of the upper mantle, some appear to flatten and stagnate, while others seemingly go through unimpeded. This variable resistance to slab sinking has been proposed to affect long-term thermal and chemical mantle circulation. A review of observational constraints and dynamic models highlights that neither the increase in viscosity between upper and lower mantle (likely by a factor 20-50) nor the coincident endothermic phase transition in the main mantle silicates (with a likely Clapeyron slope of -1 to -2 MPa/K) suffice to stagnate slabs. However, together the two provide enough resistance to temporarily stagnate subducting plates, if they subduct accompanied by significant trench retreat. Older, stronger plates are more capable of inducing trench retreat, explaining why backarc spreading and flat slabs tend to be associated with old-plate subduction. Slab viscosities that are ~2 orders of magnitude higher than background mantle (effective yield stresses of 100-300 MPa) lead to similar styles of deformation as those revealed by seismic tomography and slab earthquakes. None of the current transition-zone slabs seem to have stagnated there more than 60 m.y. Since modeled slab destabilization takes more than 100 m.y., lower-mantle entry is apparently usually triggered (e.g., by changes in plate buoyancy). Many of the complex morphologies of lower-mantle slabs can be the result of sinking and subsequent deformation of originally stagnated slabs, which can retain flat morphologies in the top of the lower mantle, fold as they sink deeper, and eventually form bulky shapes in the deep mantle.

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Thermoelasticity of Silicate Perovskite and Magnesiowüstite and Stratification of the Earth's Mantle

Cited by 157 publications

References 29 publications

Thermal Conductivity of Periclase (MgO) from First Principles

Thermal Conductivity of Periclase (MgO) from First Principles

Towards a quantitative interpretation of global seismic tomography

Subduction-transition zone interaction: A review

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