Davies, C orcid.org/0000-0002-1074-3815 and Constable, C (2017) Geomagnetic spikes on the core-mantle boundary. Nature Communications, 8. 15593. ISSN 2041-1723
Abstract
Extreme variations of Earth’s magnetic field occurred in the Levant region around 1000 BC, when the field intensity rapidly rose and fell by a factor of 2. No coherent link currently exists between this intensity spike and the global field produced by the core geodynamo. Here we show that the Levantine spike must span >60° longitude at Earth’s surface if it originates from the core–mantle boundary (CMB). Several low intensity data are incompatible with this geometric bound, though age uncertainties suggest these data could have sampled the field before the spike emerged. Models that best satisfy energetic and geometric constraints produce CMB spikes 8–22° wide, peaking at O(100) mT. We suggest that the Levantine spike reflects an intense CMB flux patch that grew in place before migrating northwest, contributing to growth of the dipole field. Estimates of Ohmic heating suggest that diffusive processes likely govern the ultimate decay of geomagnetic spikes.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Author(s) 2017. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
Keywords: | Core processes, Geomagnetism, Paleomagnetism |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Funding Information: | Funder Grant number NERC NE/L011328/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 06 Jun 2017 09:09 |
Last Modified: | 22 Jul 2020 13:47 |
Status: | Published |
Publisher: | Nature Publishing Group |
Identification Number: | 10.1038/ncomms15593 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:117280 |