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Russian Geology and Geophysics

2013 year, number 3

POSSIBLE CONTRIBUTION OF LOWER-MANTLE MAGNESIOWÜSTITE METALLIZATION INTO GEOMAGNETIC DATA

V.V. Plotkin, P.G. Dyadkov, S.G. Ovchinnikov
Keywords: Magnesiowüstite, metallization, phase change, lower mantle, conductivity, magnetic susceptibility, global electromagnetic induction, geomagnetic variation, geomagnetic observatories
Pages: 263-271

Abstract

Phase change of dielectric magnesiowüstite in the lower mantle may leave signatures in geomagnetic records of the globally distributed array of observatories. We investigate theoretically the assumed contribution of magnesiowüstite metallization to geomagnetic data and how the variations of magnetic susceptibility associated with this phase change may influence the Earths field. The modeling is performed using spherical harmonic analysis (SHA) of mantle electromagnetic (EM) responses in observatory geomagnetic data at periods of decades, 11 years, 1 year, and 27 days. The existence of a lower mantle conductor is checked against monthly means of real observatory records from 1920 through 2009 obtained by preliminary processing.