Plate motion and a dipolar geomagnetic field at 3.25 Ga

The paleomagnetic record is an archive of Earth’s geophysical history, informing reconstructions of ancient plate motions and probing the core via the geodynamo. We report a robust 3.25-billion-year-old (Ga) paleomagnetic pole from the East Pilbara Craton, Western Australia. Together with previous r...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2022-11, Vol.119 (44), p.1-7
Main Authors: Brenner, Alec R., Fu, Roger R., Kylander-Clark, Andrew R. C., Hudak, George J., Foley, Bradford J.
Format: Article
Language:English
Subjects:
Dynamo theory
Geodynamics
Geological Phenomena
Geomagnetic field
Geomagnetism
Paleomagnetism
Physical Sciences
Plate tectonics
Polar wandering
Polar wandering (geology)
Western Australia
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Summary:The paleomagnetic record is an archive of Earth’s geophysical history, informing reconstructions of ancient plate motions and probing the core via the geodynamo. We report a robust 3.25-billion-year-old (Ga) paleomagnetic pole from the East Pilbara Craton, Western Australia. Together with previous results from the East Pilbara between 3.34 and 3.18 Ga, this pole enables the oldest reconstruction of time-resolved lithospheric motions, documenting 160 My of both latitudinal drift and rotation at rates of at least 0.55°/My. Motions of this style, rate, and duration are difficult to reconcile with true polar wander or stagnant-lid geodynamics, arguing strongly for mobile-lid geodynamics by 3.25 Ga. Additionally, this pole includes the oldest documented geomagnetic reversal, reflecting a stably dipolar, core-generated Archean dynamo.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.2210258119