Wilson, Alfred J;
Pozzo, Monica;
Alfè, Dario;
Walker, Andrew M;
Greenwood, Sam;
Pommier, Anne;
Davies, Christopher J;
(2022)
Powering Earth’s ancient dynamo with silicon precipitation.
Geophysical Research Letters
, 49
(22)
, Article e2022GL100692. 10.1029/2022gl100692.
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Abstract
Earth's core has produced a global magnetic field for at least the last 3.5 Gyrs, presently sustained by inner core (IC) growth. Models of the core with high thermal conductivity suggest potentially insufficient power available for the geodynamo prior to IC formation ∼1 Ga. Precipitation of silicon from the liquid core might offer an alternative power source for the ancient magnetic field, although few estimates of the silicon partition coefficient exist for conditions of the early core. We present the first ab initio determination of the silicon partition coefficient at core-mantle boundary conditions and use these results to confirm a thermodynamic description of partitioning that is integrated into a model of coupled core-mantle thermal evolution. We show that models including precipitation of silicon can satisfy constraints of IC size, mantle convective heat flux, mantle temperature and a persistent ancient geodynamo, and favor an oxygen poor initial core composition.
| Type: | Article |
|---|---|
| Title: | Powering Earth’s ancient dynamo with silicon precipitation |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1029/2022gl100692 |
| Publisher version: | https://doi.org/10.1029/2022GL100692 |
| Language: | English |
| Additional information: | © 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
| Keywords: | Thermal history, ab initio, silicon partitioning, geodynamo, precipitation |
| UCL classification: | UCL 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-pp.ucl.ac.uk/id/eprint/10159863 |
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