LONGITUDINAL CONFINEMENT OF GEOMAGNETIC REVERSAL PATHS AS A POSSIBLE SEDIMENTARY ARTIFACT

THE positions of the virtual geomagnetic pole (VGP) during a large number of reversals of the Earth's magnetic field seem to show a remarkable confinement to longitudes over the Americas or to antipodal longitudes1,2, although it has been argued that this confinement is statistically insufficiently constrained3. It has also been pointed out4 that the same bands of longitude appear in other geophysical observations, such as the pattern of fluid motion in the outer core and regions of higher seismic velocities in the lower mantle, suggesting a causal relationship. Here we show that longitudinal confinement of VGPs can arise from the smoothing of non-antipodal stable directions (just) before and after a geomagnetic reversal, because of the filtering effect of the remanence acquisition process in sediments. The origin of this non-antipodality is still uncertain and must remain speculative until more reversal records become available that include sufficiently long pre- and post-transitional intervals.