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

Masayuki Hyodo Orcid Logo, Takeshi Nakagawa Orcid Logo, Hayato Matsushita, Ikuko Kitaba, Keitaro Yamada Orcid Logo, Shota Tanabe, Balázs Bradák Orcid Logo, Masako Miki, Danielle McLean, Richard A. Staff Orcid Logo, Victoria C. Smith Orcid Logo, Paul Albert Orcid Logo, Christopher Bronk Ramsey Orcid Logo, Akiteru Yamasaki, Junko Kitagawa, Gordon Schlolaut, Katsuya Gotanda, Kosuke Tsumura, Kaito Inagawa, Koyo Kumazawa, Haruka Abe, Saki Sugo, Koki Takahashi, Atsumi Kitamura, (Suigetsu 2014 Project)

Communications Earth & Environment, Volume: 3, Issue: 1

Swansea University Authors: Danielle McLean, Paul Albert Orcid Logo

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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,...

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Published in: Communications Earth & Environment
ISSN: 2662-4435
Published: Springer Science and Business Media LLC 2022
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa59815
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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.
College: Faculty of Science and Engineering
Funders: This study was supported by grants 15H02143, 16J10887, 18K03804 and 18H03609 from the Japan Society for the Promotion of Science
Issue: 1