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 in the banded iron formation from the northeastern Isua Supracrustal belt. Magnetite in the banded iron formation has a Pb-Pb age of 3.7 Ga (Frei et al., 1999). The U-Pb...
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ftzenodo:oai:zenodo.org:8052859 2024-09-15T18:09:51+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 Mojzsis, Steve Watson, Bruce Cherniak, Daniele 2023-06-18 https://doi.org/10.5281/zenodo.8052859 unknown Zenodo https://doi.org/10.5281/zenodo.8052858 https://doi.org/10.5281/zenodo.8052859 oai:zenodo.org:8052859 info:eu-repo/semantics/openAccess info:eu-repo/semantics/other 2023 ftzenodo https://doi.org/10.5281/zenodo.805285910.5281/zenodo.8052858 2024-07-26T12:43:01Z We present paleomagnetic field tests that hint that a record of Earth’s 3.7-billion-year (Ga) old magnetic field may be preserved in the banded iron formation from the northeastern Isua Supracrustal belt. Magnetite in the banded iron formation has a Pb-Pb age of 3.7 Ga (Frei et al., 1999). The U-Pb system has a closure temperature between 150-400°C for the magnetite grain size range observed in the banded iron formation, 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 have avoided thermal overprints from subsequent igneous intrusions. We demonstrate that specimens that pass this test also go on to pass fold and reversal tests. We argue that the banded iron formation acquired a chemical remanent magnetization via magnetite growth during a multi-phase Eoarchean metamorphic event. We recover what appears to be the oldest known whole rock record of the geomagnetic field, and oldest known records of reversals and secular variation suggesting that Earth’s magnetic field behaviour in the Eoarchean may have been similar to that observed today. Other/Unknown Material Greenland Zenodo |
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We present paleomagnetic field tests that hint that a record of Earth’s 3.7-billion-year (Ga) old magnetic field may be preserved in the banded iron formation from the northeastern Isua Supracrustal belt. Magnetite in the banded iron formation has a Pb-Pb age of 3.7 Ga (Frei et al., 1999). The U-Pb system has a closure temperature between 150-400°C for the magnetite grain size range observed in the banded iron formation, 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 have avoided thermal overprints from subsequent igneous intrusions. We demonstrate that specimens that pass this test also go on to pass fold and reversal tests. We argue that the banded iron formation acquired a chemical remanent magnetization via magnetite growth during a multi-phase Eoarchean metamorphic event. We recover what appears to be the oldest known whole rock record of the geomagnetic field, and oldest known records of reversals and secular variation 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 Mojzsis, Steve Watson, Bruce Cherniak, Daniele |
spellingShingle |
Nichols, Claire Weiss, Ben Eyster, Athena Martin, Craig Maloof, Adam Kelly, Nigel Zawaski, Mike Mojzsis, Steve Watson, Bruce 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 Mojzsis, Steve Watson, Bruce 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 |
Zenodo |
publishDate |
2023 |
url |
https://doi.org/10.5281/zenodo.8052859 |
genre |
Greenland |
genre_facet |
Greenland |
op_relation |
https://doi.org/10.5281/zenodo.8052858 https://doi.org/10.5281/zenodo.8052859 oai:zenodo.org:8052859 |
op_rights |
info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5281/zenodo.805285910.5281/zenodo.8052858 |
_version_ |
1810447440775479296 |