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Intermittent non-axial dipolar-field dominance of twin Laschamp excursions

Abstract:
Geomagnetic excursions represent the dynamic nature of the geodynamo. Accumulated palaeomagnetic records indicate that such excursions are dominated by dipolar-fields, but exhibit different structures. Here we report a palaeomagnetic record from the varved sediments of Lake Suigetsu, central Japan, which reveals fine structures in the Laschamp Excursion and a new post-Laschamp excursion that coincides with the Δ14C maxima. The record’s high-resolution chronology provides IntCal20 mid-ages and varve-counted durations. Both excursions comprise multiple subcentennial directional-swings. Simulations of filtering effects on sediment-magnetisations demonstrate that this high-resolution record replicates most of the features in existing, lower-resolution Laschamp excursion records, including the apparent clockwise open-loop of the virtual geomagnetic pole pass. The virtual geomagnetic poles during the ‘swing’ phases make four clusters centred in hemispherically-symmetric regions, three of which encompass the virtual geomagnetic poles associated with the Laschamp Excursion recorded in lavas at various locations. The stationary dipolar-field sources under each cluster should have intermittently dominated one after another during the excursions.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1038/s43247-022-00401-0

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Role:
Author
ORCID:
0000-0002-6398-5498
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Role:
Author
ORCID:
0000-0003-0831-6803
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Role:
Author
ORCID:
0000-0003-0611-8133


Publisher:
Springer Nature
Journal:
Communications Earth and Environment More from this journal
Volume:
3
Article number:
79
Publication date:
2022-04-04
Acceptance date:
2022-03-02
DOI:
EISSN:
2662-4435


Language:
English
Keywords:
Pubs id:
1250477
Local pid:
pubs:1250477
Deposit date:
2022-04-13

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