True dipole wander

Peter Olson (1, 2) , Maylis Landeau (3) , Evan Reynolds (4)

1 Morton K. Blaustein Department of Earth and Planetary Sciences [Baltimore]
2 Univ New Mexico, Dept Earth & Planetary Sci, Albuquerque, NM 87131 USA
3 IPG Paris - Institut de Physique du Globe de Paris
4 Mobile USA, Bellevue, WA 98006 USA

S U M M A R Y A fundamental assumption in palaeomagnetism is that the geomagnetic field closely approximates a geocentric axial dipole in time average. Here we use numerical dynamos driven by heterogeneous core-mantle boundary heat flux from a mantle global circulation model to demonstrate how mantle convection produces true dipole wander, rotation of the geomagnetic dipole on geologic timescales. Our heterogeneous mantle-driven dynamos show a dipole rotation about a near-equatorial axis in response to the transition in lower mantle heterogeneity from a highly asymmetric pattern at the time of supercontinent Pangea to a more symmetric pattern today. This predicted dipole rotation overlaps with a palaeomagnetically inferred rotation in the opposite direction and suggests that some events previously interpreted as true polar wander also include true dipole wander.

Mots clés: Reversals; Dynamics: convection currents and mantle plumes; Core; Mantle processes; Dynamo theories and simulations; Palaeomagnetism

Domaines: Planète et Univers [physics]; Sciences de la Terre

Peter Olson, Maylis Landeau, Evan Reynolds. True dipole wander. Geophysical Journal International, 2018, 215 (3), pp.1523 - 1529. ⟨10.1093/gji/ggy349⟩. ⟨insu-02930249⟩