Possible Eoarchean records of the geomagnetic field preserved in the Isua Supracrustal Belt, southern west Greenland
We present paleomagnetic field tests that hint that a record of Earth’s 3.7-billion-year (Ga) old magnetic field may be preserved as a chemical remanent magnetization acquired during amphibolite-grade metamorphism in the banded iron formation from the northeastern Isua Supracrustal Belt. Multiple pe...
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California Digital Library (CDL)
2023
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crescholarship:10.31223/x5sx0v 2024-03-03T08:36:32+00:00 Possible Eoarchean records of the geomagnetic field preserved in the Isua Supracrustal Belt, southern west Greenland Nichols, Claire Weiss, Ben Eyster, Athena Martin, Craig Maloof, Adam Kelly, Nigel Zawaski, Mike Watson, E. Bruce Mojzsis, Stephen Cherniak, Daniele 2023 http://dx.doi.org/10.31223/x5sx0v unknown California Digital Library (CDL) posted-content 2023 crescholarship https://doi.org/10.31223/x5sx0v 2024-02-07T10:56:39Z We present paleomagnetic field tests that hint that a record of Earth’s 3.7-billion-year (Ga) old magnetic field may be preserved as a chemical remanent magnetization acquired during amphibolite-grade metamorphism in the banded iron formation from the northeastern Isua Supracrustal Belt. Multiple petrological and geochronological lines of evidence indicate that the northern most part of Isua has not experienced metamorphic temperatures exceeding 350◦C since the Eoarchean, suggesting the rocks have not been significantly heated since magnetization was acquired. We use a ‘pseudo’ baked contact test to assess paleodirections in the banded iron formation that pre-date the intrusion of the 3.26-3.5 Ga Ameralik dyke swarm. We demonstrate that specimens that pass this test also go on to pass a fold test and may also pass a reversal test. We recover what appears to be the oldest known whole rock record of the geomagnetic field, and oldest known records of reversals suggesting that Earth’s magnetic field behaviour in the Eoarchean may have been similar to that observed today. Other/Unknown Material Ameralik Greenland eScholarship Repository (University of California) Ameralik ENVELOPE(-51.000,-51.000,64.117,64.117) Greenland |
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eScholarship Repository (University of California) |
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description |
We present paleomagnetic field tests that hint that a record of Earth’s 3.7-billion-year (Ga) old magnetic field may be preserved as a chemical remanent magnetization acquired during amphibolite-grade metamorphism in the banded iron formation from the northeastern Isua Supracrustal Belt. Multiple petrological and geochronological lines of evidence indicate that the northern most part of Isua has not experienced metamorphic temperatures exceeding 350◦C since the Eoarchean, suggesting the rocks have not been significantly heated since magnetization was acquired. We use a ‘pseudo’ baked contact test to assess paleodirections in the banded iron formation that pre-date the intrusion of the 3.26-3.5 Ga Ameralik dyke swarm. We demonstrate that specimens that pass this test also go on to pass a fold test and may also pass a reversal test. We recover what appears to be the oldest known whole rock record of the geomagnetic field, and oldest known records of reversals suggesting that Earth’s magnetic field behaviour in the Eoarchean may have been similar to that observed today. |
format |
Other/Unknown Material |
author |
Nichols, Claire Weiss, Ben Eyster, Athena Martin, Craig Maloof, Adam Kelly, Nigel Zawaski, Mike Watson, E. Bruce Mojzsis, Stephen Cherniak, Daniele |
spellingShingle |
Nichols, Claire Weiss, Ben Eyster, Athena Martin, Craig Maloof, Adam Kelly, Nigel Zawaski, Mike Watson, E. Bruce Mojzsis, Stephen Cherniak, Daniele Possible Eoarchean records of the geomagnetic field preserved in the Isua Supracrustal Belt, southern west Greenland |
author_facet |
Nichols, Claire Weiss, Ben Eyster, Athena Martin, Craig Maloof, Adam Kelly, Nigel Zawaski, Mike Watson, E. Bruce Mojzsis, Stephen Cherniak, Daniele |
author_sort |
Nichols, Claire |
title |
Possible Eoarchean records of the geomagnetic field preserved in the Isua Supracrustal Belt, southern west Greenland |
title_short |
Possible Eoarchean records of the geomagnetic field preserved in the Isua Supracrustal Belt, southern west Greenland |
title_full |
Possible Eoarchean records of the geomagnetic field preserved in the Isua Supracrustal Belt, southern west Greenland |
title_fullStr |
Possible Eoarchean records of the geomagnetic field preserved in the Isua Supracrustal Belt, southern west Greenland |
title_full_unstemmed |
Possible Eoarchean records of the geomagnetic field preserved in the Isua Supracrustal Belt, southern west Greenland |
title_sort |
possible eoarchean records of the geomagnetic field preserved in the isua supracrustal belt, southern west greenland |
publisher |
California Digital Library (CDL) |
publishDate |
2023 |
url |
http://dx.doi.org/10.31223/x5sx0v |
long_lat |
ENVELOPE(-51.000,-51.000,64.117,64.117) |
geographic |
Ameralik Greenland |
geographic_facet |
Ameralik Greenland |
genre |
Ameralik Greenland |
genre_facet |
Ameralik Greenland |
op_doi |
https://doi.org/10.31223/x5sx0v |
_version_ |
1792507257374638080 |