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

Hyodo, M. et al. (2022) Intermittent non-axial dipolar-field dominance of twin Laschamp excursions. Communications Earth and Environment, 3(1), 79. (doi: 10.1038/s43247-022-00401-0)

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.

• Item Type: Articles
• Additional Information: This study was supported by grants 15H02143, 16J10887, 18K03804 and 18H03609 from the Japan Society for the Promotion of Science. Part of this study was performed in collaboration with the Center for Advanced Marine Core Research, Kochi University (reference numbers: 14A023, 15A001, 16A002, 18A014 and 19A020) and with the support of JAMSTEC. The 2014 field campaign to obtain the studied sediment core (Fukui-SG14) was funded by Fukui Prefecture, Japan.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Staff, Dr Richard
• Authors: Hyodo, M., Nakagawa, T., Matsushita, H., Kitaba, I., Yamada, K., Tanabe, S., Bradák, B., Miki, M., McLean, D., Staff, R. A., Smith, V. C., Albert, P. G., Bronk Ramsey, C., Yamasaki, A., and Kitagawa, J.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Communications Earth and Environment
• Publisher: Nature Research
• ISSN: 2662-4435
• ISSN (Online): 2662-4435
• Copyright Holders: Copyright © 2022 The Authors
• First Published: First published in Communications Earth and Environment 3(1):79
• Publisher Policy: Reproduced under a Creative Commons License