Structure and Dynamics of Liquid Iron under Earth's Core Conditions

First-principles molecular dynamics simulations based on density-functional theory and the projector augmented wave (PAW) technique have been used to study the structural and dynamical properties of liquid iron under Earth's core conditions. As evidence for the accuracy of the techniques, we present PAW results for a range of solid-state properties of low- and high-pressure iron, and compare them with experimental values and the results of other first-principles calculations. In the liquid-state simulations, we address particular effort to the study of finite-size effects, Brillouin-zone sampling and other sources of technical error. Results for the radial distribution function, the diffusion coefficient and the shear viscosity are presented for a wide range of thermodynamic states relevant to the Earth's core. Throughout this range, liquid iron is a close-packed simple liquid with a diffusion coefficient and viscosity similar to those of typical simple liquids under ambient conditions.Comment: 13 pages, 8 figure

A new thermal and rheological model of the European lithosphere

We present a new thermal and rheological model of the European lithosphere (10°W-35°E; 35°N-60°N), which is based on a combination of recently obtained geophysical models. To determine temperature distribution we use a new tomography model, which is principally improved by an a-priori correction of the crustal effect, by using EuCRUST-07, a new digital model of the European crust. The inversion approach is similar to those used in previous studies, but the employment of a more robust tomography model essentially improves the result. The uppermost mantle under western and central Europe is mostly characterized by temperatures in a range of 900°-1100 °C, with the hottest areas corresponding to the basins, which have experienced recent extension (e.g. Tyrrhenian Sea and Pannonian Basin). By contrast, the mantle temperatures under eastern Europe are about 550°-750 °C at the same depth and the minimum values are found in the northeastern part of the study area. The new temperature estimates are used to trace the lithosphere-asthenosphere thermal boundary, as a depth of the isotherm of 1200 °C. The lithospheric thickness is less than 100 km beneath the hottest part of western and central Europe, while the maximum values are observed beneath the East European Platform (200-230 km), the Alps and the Dinarides-Hellenic Arc (150-180 km). EuCRUST-07 and the new thermal model are used to calculate the strength distribution within the European lithosphere. Differently from previous estimates, the new model adopts lateral variations of lithology and density, which are derived from the crustal model. According to these estimates, in western and central Europe the lithosphere is more heterogeneous than in eastern Europe, the latter being generally characterized by higher strength values. These strength variations are also in a good agreement with other geophysical characteristics of the lithosphere such as residual mantle gravity anomalies. © 2009 Elsevier B.V. All rights reserved