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Composition and temperature of the Earth's core constrained by combining ab initio calculations and seismic data
 

Summary: Composition and temperature of the Earth's core constrained
by combining ab initio calculations and seismic data
D. Alfe© aYb
, M.J. Gillan bY
*, G.D. Price a
a
Research School of Geological and Geophysical Sciences, Birkbeck College and University College London, Gower Street,
London WC1E 6BT, UK
b
Physics and Astronomy Department, University College London, Gower Street, London WC1E 6BT, UK
Received 11 May 2001; received in revised form 21 September 2001; accepted 26 October 2001
Abstract
It is shown how ab initio techniques based on density functional theory can be used to calculate the chemical
potentials of the leading candidate impurity elements (S, O and Si) in the Earth's solid inner core and liquid outer core.
The condition that these chemical potentials be equal in the solid and liquid phases provides values for the ratios of the
impurity mol fractions in the inner and outer core. By combining the estimated ratios with ab initio values for the
impurity molar volumes in the two phases, and demanding that the resulting density discontinuity across the inner-core
boundary agree with free-oscillation data, we obtain estimates for the concentrations of S, O and Si in the core. The
results show that O partitions much more strongly than S and Si from solid to liquid, and indicate that the presence of O
in the core is essential to account for seismic measurements. We suggest that if compositional convection drives the

  

Source: Alfè, Dario - Departments of Earth Sciences & Physics and Astronomy, University College London
Price, G. David - Department Earth Sciences, University College London

 

Collections: Geosciences; Materials Science; Physics