Preferred reversal paths caused by a heterogeneous conducting layer at the base of the mantle

Time variations in the geomagnetic field induce secondary electric currents in the mantle, which contribute to the magnetic field at the surface. We explore the possibility that currents in a conducting layer at the base of the mantle disturb the transition field during magnetic reversals and alter the path of the virtual geomagnetic pole (VGP). We calculate the magnitude of the magnetic perturbation during a reversal and quantify the influence of this perturbation on the VGP reversal path. The calculations show that the VGP reversal path depends on the geographic position of the observation site. A histogram of reversal paths obtained using a randomly distributed set of sites reveals a preferred path through the Americas. When the histogram of reversal paths is evaluated with a limited number of sites, based on locations in existing lava and sediment databases, we find that the paths are confined to Asian and American longitudes, which is compatible with reversal path distributions inferred from paleomagnetic records.