Possible contribution of lower mantle magnesiowüstite metallization into geomagnetic data

• Published in: Russian geology and geophysics Vol. 54; no. 3; pp. 263 - 271
• Main Authors: Plotkin, V.V., Dyad'kov, P.G., Ovchinnikov, S.G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2013; Allerton Press
• Subjects: conductivity; electrical conductivity; electromagnetic field; electromagnetic induction; ferropericlase; geomagnetic observatories; geomagnetic variation; Geophysics; global; global electromagnetic induction; lower mantle; magnesiowüstite; magnetic field; magnetic properties; magnetic susceptibility; mantle; mathematical models; metallization; observations; oxides; paleomagnetism; phase change; solid Earth (tectonophysics); spherical harmonic analysis; theoretical studies; magnesiowüstite; metallization; phase change; lower mantle; conductivity; global electromagnetic induction; geomagnetic variation; magnetic susceptibility; geomagnetic observatories
• ISSN: 1068-7971; 1878-030X
• DOI: 10.1016/j.rgg.2013.02.002

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 which may be the contribution of magnesiowüstite metallization to geomagnetic data and how the variations of magnetic susceptibility associated with this phase change may influence the Earth's 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.