Possible Eoarchean Records of the Geomagnetic Field Preserved in the Isua Supracrustal Belt, Southern West Greenland
- Autor(en)
- Claire I.O. Nichols, Benjamin P. Weiss, Athena Eyster, Craig R. Martin, Adam C. Maloof, Nigel M. Kelly, Mike J. Zawaski, Stephen J. Mojzsis, E. Bruce Watson, Daniele J. Cherniak
- Abstrakt
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.
- Organisation(en)
- Department für Lithosphärenforschung
- Externe Organisation(en)
- Massachusetts Institute of Technology, University of Oxford, Tufts University, Princeton University, Bruker Nano Analytics, University of Colorado, Boulder, Texas A&M University, MTA Társadalomtudományi Kutatóközpont, Friedrich-Schiller-Universität Jena, Rensselaer Polytechnic Institute, State University of New York, Albany
- Journal
- Journal of Geophysical Research: Solid Earth
- Band
- 129
- ISSN
- 2169-9313
- DOI
- https://doi.org/10.1029/2023JB027706
- Publikationsdatum
- 04-2024
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105105 Geochemie
- Schlagwörter
- ASJC Scopus Sachgebiete
- Geophysics, Geochemistry and Petrology, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous)
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/d8c9fca4-2287-44c1-ad8e-78671c10ffbf