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

• Main Author: Costin, Simona E.O.
• Format: Text
• Language: English
• Published: University of British Columbia 2009
• Subjects: Geomagnetic Pole
• Online Access: https://dx.doi.org/10.14288/1.0052400; https://doi.library.ubc.ca/10.14288/1.0052400

Paleomagnetic data from sedimentary and volcanic rocks suggest that the positions of the Virtual Geomagnetic Pole (VGP) during polarity reversals over the past few million years are confined to longitudes through the Americas and Asia. In this study I examine the possibility that lateral conductivity variations in the lowermost region of the mantle contribute to the geographical distribution of the reversal paths. The conductivity model consists of a thin layer of material with variable electrical properties which accumulates in the core-mantle boundary region. The pattern of conductivity relies on the geodynamic predictions of the boundary topography and is in good agreement with the seismological observations of heterogeneities at the core-mantle boundary. Temporal variations in the dipole field during a reversal generate electric currents in the conductive layer, which in turn produce a secondary magnetic field. Superposition of the secondary field on a transition field affects the declination and ...