Two different R–N geomagnetic reversals with identical VGP paths recorded at the same site

Abstract

We have studied two reverse–normal (R–N) geomagnetic reversals recorded at different stratigraphical levels of a single section of Tortonian marine clays in western Crete. We report here that the virtual geomagnetic pole (VGP) paths associated with these two transitions, which are separated in time by a period of ∼1 Myr, are identical. Although the possibility of an accidental coincidence cannot be rejected, this result suggests that the basic mechanisms in the geodynamo leading to a reversal might persist unchanged over a long period of time. Moreover, the two VGP paths are largely constrained in longitude along a mean great circle located ∼80°W of the site, so that the transitional field cannot be correctly described in terms of pure axial symmetry.