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Robust Characteristics of the Laschamp and Mono Lake Geomagnetic Excursions: Results From Global Field Models

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dc.contributor Háskóli Íslands
dc.contributor University of Iceland
dc.contributor.author Korte, Monika
dc.contributor.author Brown, Maxwell
dc.contributor.author Panovska, Sanja
dc.contributor.author Wardinski, Ingo
dc.date.accessioned 2020-04-30T14:10:16Z
dc.date.available 2020-04-30T14:10:16Z
dc.date.issued 2019-04-30
dc.identifier.citation Korte M, Brown MC, Panovska S and Wardinski I (2019) Robust Characteristics of the Laschamp and Mono Lake Geomagnetic Excursions: Results From Global Field Models. Frontiers in Earth Science 7:86. doi: 10.3389/feart.2019.00086
dc.identifier.issn 2296-6463
dc.identifier.uri https://hdl.handle.net/20.500.11815/1765
dc.description Publisher's version (útgefin grein)
dc.description.abstract Data-based global paleomagnetic field models provide a more complete view of geomagnetic excursions than individual records. They allow the temporal and spatial field evolution to be mapped globally, and facilitate investigation of dipole and non-dipole field components. We have developed a suite of spherical harmonic (SH) field models that span 50–30 ka and include the Laschamp (~41 ka) and Mono Lake (~33 ka) excursions. Paleomagnetic field models depend heavily on the data used in their construction. Variations in paleomagnetic sediment records from the same region are in some cases inconsistent. To test the influence of data selection and reliance on age models, we have built a series of SH models based upon different data sets. A number of excursion characteristics are robust in all models, despite some differences in energy distribution among SH coefficients. Quantities, such as field morphology at the core-mantle boundary (CMB) or individual SH degree power variations should be interpreted with caution. All models suggest that the excursion process during the Laschamp is mainly governed by axial dipole decay and recovery, without a significant influence from the equatorial dipole or non-dipole fields. The axial dipole component reduces to almost zero, but does not reverse. This results in excursional field behavior seen globally, but non-uniformly at Earth's surface. The Mono Lake excursion may be a series of excursions occurring between 36 and 30 ka rather than a single excursion. In contrast to the Laschamp, these excursions appear driven by smaller decreases in axial dipole field strength during a time when the axial dipole power at the CMB is similar to the power in the non-dipole field. We suggest three phases for the 50 to 30 ka period: (1) a broadly stable phase dominated by the axial dipole (50–43 ka); (2) the Laschamp excursion, with the underlying excursion process lasting ~5 ka (43–38 ka) and the surface field expression lasting ~2 ka (42–40 ka); (3) a weak phase during which axial dipole and non-dipole power at the CMB are comparable, leading to more than one excursion between 36 and 30 ka.
dc.description.sponsorship MB was supported by the Deutsche Forschungsgemeinschaft SPP PlanetMag 1488 project BR4697/1.
dc.format.extent 86
dc.language.iso en
dc.publisher Frontiers Media SA
dc.relation.ispartofseries Frontiers in Earth Science;7
dc.rights info:eu-repo/semantics/openAccess
dc.subject Geomagnetic field
dc.subject Global magnetic field models
dc.subject Laschamp excursion
dc.subject Mono lake excursion
dc.subject Paleomagnetism
dc.subject Jarðsegulsvið
dc.subject Bergsegulmælingar
dc.subject Líkön
dc.title Robust Characteristics of the Laschamp and Mono Lake Geomagnetic Excursions: Results From Global Field Models
dc.type info:eu-repo/semantics/article
dcterms.license This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
dc.description.version Peer Reviewed
dc.identifier.journal Frontiers in Earth Science
dc.identifier.doi 10.3389/feart.2019.00086
dc.relation.url https://www.frontiersin.org/article/10.3389/feart.2019.00086/full
dc.contributor.department Jarðvísindastofnun (HÍ)
dc.contributor.department Institute of Earth Sciences (UI)
dc.contributor.school Verkfræði- og náttúruvísindasvið (HÍ)
dc.contributor.school School of Engineering and Natural Sciences (UI)

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