The signature of inner-core nucleation on the geodynamo - INSU - Institut national des sciences de l'Univers Access content directly
Journal Articles Earth and Planetary Science Letters Year : 2017

The signature of inner-core nucleation on the geodynamo


Energy considerations indicate that the power delivered to the present-day geodynamo comes mainly from the growth of the solid inner core, through light element and latent heat releases. The nucleation of the inner core was, therefore, a major transition for the geodynamo. Here, we use numerical dynamo simulations linked by thermochemical evolution of the core to investigate the effects of inner-core nucleation (ICN) on the geodynamo, and identify possible ICN footprints in the palaeomagnetic field. Our results suggest that a strong-field dipole-dominated dynamo prior and after ICN (the uniformitarian scenario) is most likely. We predict little footprint of ICN on the surface field intensity, consistent with the observed lack of a long-term trend in paleointensity data. Instead, we find that the best proxy for inner-core growth is an increase in axial octupole strength with age, from present-day to ICN, which might be resolvable in the palaeomagnetic record. We confirm the existence of weak-field, multipolar dynamos prior to ICN, suggesting the dynamo might have transiently reached a weak-field state (the catastrophic scenario). The narrow stability domain of these weak-field dynamos implies that the catastrophic scenario is less probable than the uniformitarian scenario.
Fichier principal
Vignette du fichier
S0012821X1730064X.pdf (17.07 Mo) Télécharger le fichier
Origin Files produced by the author(s)

Dates and versions

insu-02918346 , version 1 (21-08-2020)



Maylis Landeau, Julien Aubert, Peter Olson. The signature of inner-core nucleation on the geodynamo. Earth and Planetary Science Letters, 2017, 465, pp.193-204. ⟨10.1016/j.epsl.2017.02.004⟩. ⟨insu-02918346⟩
61 View
56 Download



Gmail Mastodon Facebook X LinkedIn More