ORCID Profile
0000-0002-6602-0990
Current Organisation
University of Leeds
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Publisher: American Geophysical Union (AGU)
Date: 17-11-2022
DOI: 10.1029/2022GL100692
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.
Publisher: American Physical Society (APS)
Date: 23-06-2021
Publisher: California Digital Library (CDL)
Date: 26-03-2023
DOI: 10.31223/X50M2C
Publisher: California Digital Library (CDL)
Date: 17-06-2022
DOI: 10.31223/X5H34M
Abstract: Earth's core has produced a global magnetic field for the last 4 Gyrs, presently sustained by inner core growth.Models of the core with high thermal conductivity suggest potentially insufficient power available for the geodynamo prior to inner core formation ~1 Ga.Precipitation of SiO2 from the liquid core might offer an alternative power source for the magnetic field before inner core growth, however, no estimates of partition coefficient exist for conditions of the early core.We present the first determination of the silicon partition coefficient at core-mantle boundary conditions and use these results to build a thermodynamic model that is integrated into a model of coupled core-mantle thermal evolution.We show that models including precipitation of silicon can satisfy constraints of inner core size, mantle convective heat flux, mantle temperature and a persistent ancient geodynamo whilst those excluding fail.Successful power from precipitation favours an oxygen poor initial core composition.
Publisher: California Digital Library (CDL)
Date: 07-04-2023
DOI: 10.31223/X5BT0S
Abstract: We examine magnesium and potassium solubility in liquid Fe mixtures, representative of Earth’s core composition, in equilibrium with liquid silicate mixtures representative of an early magma ocean. Our study is based on the calculation of the chemical potentials of MgO and K2O in both phases, using density functional theory. For MgO, we also study stability against precipitation of the solid phase. We use thermal evolution models of the core and mantle to assess whether either radiogenic heating from 40K decay or Mg precipitation from the liquid core can resolve the new core paradox by powering the geodynamo prior to inner core formation. Our results on K show that concentrations in the core are likely to be small and the effect of 40K decay on the thermal evolution of the core is minimal, making it incapable of sustaining the early geodynamo alone. Our results also predict small concentrations of Mg in the core although these might be sufficient to power the geodynamo prior to inner core formation, depending on the process by which it is transported across the core mantle boundary.
Publisher: Elsevier BV
Date: 07-2023
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Alfred Wilson.