UCL Discovery
UCL home » Library Services » Electronic resources » UCL Discovery

Compositional instability of Earth's solid inner core

Gubbins, D; Alfe, D; Davies, CJ; (2013) Compositional instability of Earth's solid inner core. GEOPHYSICAL RESEARCH LETTERS , 40 (6) 1084 - 1088. 10.1002/grl.50186. Green open access

[img]
Preview
PDF
grl50186.pdf

Download (148kB)

Abstract

[1] All models that invoke convection to explain the observed seismic variations in Earth's inner core require unstable inner core stratification. Previous work has assumed that chemical effects are stabilizing and focused on thermal convection, but recent calculations indicate that the thermal conductivity at core temperatures and pressures is so large that the inner core must cool entirely by conduction. We examine partitioning of oxygen, sulfur, and silicon in binary iron alloys and show that inner core growth results in a variable light element concentration with time: oxygen concentration decreases, sulfur concentration decreases initially and increases later, and silicon produces a negligible effect to within the model errors. The result is a net destabilizing concentration gradient. Convective stability is measured by a Rayleigh number, which exceeds the critical value for reasonable estimates of the viscosity and diffusivity. Our results suggest that inner core convection models, including the recently proposed translational mode, can be viable candidates for explaining seismic results if the driving force is compositional.

Type: Article
Title: Compositional instability of Earth's solid inner core
Open access status: An open access version is available from UCL Discovery
DOI: 10.1002/grl.50186
Publisher version: http://dx.doi.org/10.1002/grl.50186
Additional information: ©2013. American Geophysical Union. All Rights Reserved. Full text made available to UCL Discovery by kind permission of Wiley.
Keywords: Inner core; Convection; Light elements
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
URI: https://discovery.ucl.ac.uk/id/eprint/1394315
Downloads since deposit
93Downloads
Download activity - last month
Download activity - last 12 months
Downloads by country - last 12 months

Archive Staff Only

View Item View Item