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The electrical conductivity and thermal profile of the Earth's mid-mantle

Dobson, DP; Brodholt, JP; (2000) The electrical conductivity and thermal profile of the Earth's mid-mantle. Geophysical Research Letters , 27 (15) 2325 - 2328. 10.1029/1999GL008409. Green open access

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Abstract

Electrical conductivity in the Earth's mantle is sensitive to temperature and chemical environment. Recent laboratory measurements of electrical conductivity are combined with candidate mantle geotherms to produce synthetic electrical conductivity profiles. These profiles are used to forward model the Earth's geomagnetic response function C, results of which are compared with the observed globally averaged response function at periods of 3.5 days to 4 months. Candidate lower mantle geotherms, representing whole-mantle and layered convection end-members, are compared using published electrical conductivity measurements on alumina-bearing and alumina-free perovskite in the conductivity models. Comparison of the predicted response functions with the observed geomagnetic response of the Earth shows that a) if lower mantle alumina is incorporated into perovskite, then the lower mantle must be cool, and b) if the alumina is not incorporated in perovskite then the results are only consistent with a hot lower mantle. In addition, the maximum alumina content of lower mantle MgSiO3 perovskite is constrained at 4%.

Type:Article
Title:The electrical conductivity and thermal profile of the Earth's mid-mantle
Open access status:An open access version is available from UCL Discovery
DOI:10.1029/1999GL008409
Publisher version:http://dx.doi.org/10.1029/1999GL008409
Language:English
Additional information:Copyright 2000 by the American Geophysical Union
Keywords:Silicate perovskite, Ferric iron, Laboratory measurements, Olivine, Transition, Alumina, State
UCL classification:UCL > School of BEAMS > Faculty of Maths and Physical Sciences > Earth Sciences

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