Possible Eoarchean Records of the Geomagnetic Field Preserved in the Isua Supracrustal Belt, Southern West Greenland
Name
JGR Solid Earth - 2024 - Nichols - Possible Eoarchean Records of the Geomagnetic Field Preserved in the Isua Supracrustal.pdf
Description
Published version
Size
8.14 MB
Format
Adobe PDF
Checksum (MD5)
179434b327f3bffa72e501c5e16f3819
Author(s)
Nichols, Claire IO
Weiss, Benjamin P
Eyster, Athena
Martin, Craig R
Maloof, Adam C
Kelly, Nigel M
Zawaski, Mike J
Mojzsis, Stephen J
Watson, E Bruce
Cherniak, Daniele J
Date Issued
April 24, 2024
Journal
Journal of Geophysical Research: Solid Earth
Publisher
American Geophysical Union
Citation
Nichols, Claire IO, Weiss, Benjamin P, Eyster, Athena, Martin, Craig R, Maloof, Adam C et al. 2024. "Possible Eoarchean Records of the Geomagnetic Field Preserved in the Isua Supracrustal Belt, Southern West Greenland." Journal of Geophysical Research: Solid Earth, 129 (4).
Version
Final published version
Abstract
Recovering ancient records of Earth's magnetic field is essential for determining the role of the magnetosphere in protecting early Earth from cosmic radiation and atmospheric escape. We present paleomagnetic field tests hinting that a record of Earth's 3.7‐billion‐year (Ga) old magnetic field may be preserved in the northeastern Isua Supracrustal Belt as a chemical remanent magnetization acquired during amphibolite‐grade metamorphism in the banded iron formation. Multiple petrological and geochronological lines of evidence indicate that the northernmost part of Isua has not experienced metamorphic temperatures exceeding 380°C since the Eoarchean, suggesting the rocks have not been significantly heated since magnetization was acquired. We use “pseudo” baked contact tests (intrusions emplaced 3.26–3.5 Ga ago) and a fold test (folding 3.6 Ga ago) to demonstrate that some samples preserve a ca. 3.7 Ga record of the magnetic field. We recover a field strength of >15 µT. This suggests that Earth's magnetic field may have been weak enough to enhance atmospheric escape during the Archean.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Terms of Use
Creative Commons Attribution-Noncommercial
Persistent DSpace Link
DOI of Published Version
10.1029/2023jb027706
