2,362 research outputs found
Mineral physics of the mantle
No full textThe last few years have seen intense interest in the global environment and climate change, and with it an increasing appreciation for the interactions between the atmosphere, biosphere, oceans and the solid earth. In solid earth geophysics, the traditional boundaries between the earth's fluid and solid spheres have been breached by the growing body of evidence that they may physically communicate on a massive scale, that atmospheric constituents, under certain conditions, may be transported to and stored within the deepest parts of the earth. Of course there has for some time been an appreciation for influence of mantle dynamics, the driving force of plate tectonics, volcanism, and seismicity, on surface processes. However, perhaps nothing illustrates the essential connections better than visualizing, now with some experimental and observational support, a tropospheric molecule, transported through sedimentary and tectonic agents 3000 km to the core mantle boundary, only to rise again, perhaps many millions of years later in a volcanic eruption
Heat and charge transport in H2O at ice-giant conditions from ab initio molecular dynamics simulations
No full textThe authors here perform ab initio calculations to investigate in the heat transport properties of water at extreme pressure and temperature conditions, typically found in the interior of ice giants such as Uranus and Neptune
Stixrude receives James B. Macelwane Medal
No full textPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95034/1/eost12216.pd
Reptricket. Förord till Lars Gustafsson: Mot noll
No full textIntroduction to a collection of philosophical essays by Swedish author Lars Gustafsson (b. 1936)
Thermal and Tidal Evolution of Uranus with a Growing Frozen Core
No full textThe origin of the very low luminosity of Uranus is unknown, as is the source of the internal tidal dissipation required by the orbits of the Uranian moons. Models of the interior of Uranus often assume that it is inviscid throughout, but recent experiments show that this assumption may not be justified; most of the interior of Uranus lies below the freezing temperature of H2O. We find that the stable solid phase of H2O, which is superionic, has a large viscosity controlled by the crystalline oxygen sublattice. We examine the consequences of finite viscosity by combining ab initio determinations of the thermal conductivity and other material properties of superionic H2O with a thermal evolution model that accounts for heat trapped in the growing frozen core. The high viscosity provides a means of trapping heat in the deep interior while also providing a source of tidal dissipation. The frozen core grows with time because its outer boundary is governed by the freezing transition rather than compositional layering. We find that the presence of a growing frozen core explains the anomalously low heat flow of Uranus. Our thermal evolution model also predicts time-varying tidal dissipation that matches the requirements of the orbits of Miranda, Ariel, and Umbriel. We make predictions that are testable by future space missions, including the tidal Love number of Uranus and the current recessional rates of its moons
Thermodynamics of mantle minerals – I. Physical properties
No full textWe present a theory for the computation of phase equilibria and physical properties of multicomponent assemblages relevant to the mantle of the Earth. The theory differs from previous treatments in being thermodynamically self-consistent: the theory is based on the concept of fundamental thermodynamic relations appropriately generalized to anisotropic strain and in encompassing elasticity in addition to the usual isotropic thermodynamic properties. In this first paper, we present the development of the theory, discuss its scope, and focus on its application to physical properties of mantle phases at elevated pressure and temperature including the equation of state, thermochemical properties and the elastic wave velocities. We find that the Eulerian finite strain formulation captures the variation of the elastic moduli with compression. The variation of the vibrational frequencies with compression is also cast as a Taylor series expansion in the Eulerian finite strain, the appropriate volume derivative of which leads to an expression for the GrÜneisen parameter that agrees well with results from first principles theory. For isotropic materials, the theory contains nine material-specific parameters: the values at ambient conditions of the Helmholtz free energy, volume, bulk and shear moduli, their pressure derivatives, an effective Debye temperature, its first and second logarithmic volume derivatives (Γ 0 , q 0 ) , and the shear strain derivative of Γ. We present and discuss in some detail the results of a global inversion of a wide variety of experimental data and first principles theoretical results, supplemented by systematic relations, for the values of these parameters for 31 mantle species. Among our findings is that the value of q is likely to be significantly greater than unity for most mantle species. We apply the theory to the computation of the shear wave velocity, and temperature and compositional (Fe content) derivatives at relevant mantle pressure temperature conditions. Among the patterns that emerge is that garnet is anomalous in being remarkably insensitive to iron content or temperature as compared with other mantle phases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73485/1/j.1365-246X.2005.02642.x.pd
Author Functions in Lars Kepler\u27s The Hypnotist: An Analysis
No full textThis paper examines Foucault\u27s notion of the author function as it pertains to Lars Kepler\u27s bestselling 2011 crime thriller, The Hypnotist. Lars Kepler is the pseudonym of a Swedish husband-wife writing duo, making him the perfect subject for analysis centering on illusory notion of the author. This paper will answer these questions: Who is the true author of The Hypnotist? What factors influence the author function of this bestelling novel? And what can The Hypnotist phenomenon tell us about the relationships between authors and their readers? This paper will demonstrate that no literary works may be ascribed to an individual person, and that authors hold no privileged knowledge of the works they produce, because authors cease to be authors the moment pen is lifted from page
Ab initio study of the elastic behavior of MgSiO3 ilmenite at high pressure
No full textWe investigate the athermal high pressure behavior of the elastic properties of MgSiO3 ilmenite up to 30 GPa using the ab initio pseudopotential method. Our results at zero pressure are in good agreement with single-crystal elasticity measurements. The elastic anisotropy is shown to decrease slightly under compression and hence to remain substantial (25 to 20% shear wave anisotropy and 16 to 10% longitudinal wave anisotropy) over the pressure regime studied. The directions of fastest and slowest wave propagation are found to change slightly with pressure as determined by the pressure dependence of c(14) and c(25). Comparisons with the elastic behavior of other deep transition zone phases such as ringwoodite and garnet show that ilmenite is likely to be the fastest and most anisotropic mineral in this region. Large contrasts (approximate to 10%) in velocities and densities between ilmenite and garnet are suggested to be significant for the interpretation of lateral structure in the transition zone
Stability of (Mg,Fe)SiO3 perovskite and the structure of the lowermost mantle
No full textThermodynamic analysis shows that (Mg,Fe)SiO3 perovskite is stable throughout the likely pressure, temperature and compositional regime of the Earth's mantle. The breakdown of perovskite to its constituent oxides appears unlikely, even under the extreme conditions of the core-mantle boundary. This reaction had been proposed to reconcile estimates of silicate melting with seismic observation and proposed geotherms
Data for: The potential for bridgmanite megacrysts to drive magma-ocean segregation
No full textThis repository contains the source data for the manuscript titled "The potential for bridgmanite megacrysts to drive magma-ocean segregation".
Authors: Jie Deng, Junwei Hu, Yidi Shi, Jina Lee, Haiyang Niu, and Lars Stixrude
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