Department of Geological Sciences

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Reevaluating the evidence for a Hadean-Eoarchean dynamo
(American Association for the Advancement of Science, 2020) Borlina, Caue S.; Weiss, Benjamin P.; Lima, Eduardo A.; Tang, Fengzai; Taylor, Richard J. M.; Einsle, Joshua F.; Harrison, Richard J.; Fu, Roger R.; Bell, Elizabeth A.; Alexander, Ellen W.; Kirkpatrick, Heather M.; Wielicki, Matthew M.; Harrison, T. Mark; Ramezani, Jahandar; Maloof, Adam C.; Massachusetts Institute of Technology (MIT); University of Cambridge; Imperial College London; Harvard University; University of California Los Angeles; University of Alabama Tuscaloosa; Princeton University
The time of origin of the geodynamo has important implications for the thermal evolution of the planetary interior and the habitability of early Earth. It has been proposed that detrital zircon grains from Jack Hills, Western Australia, provide evidence for an active geodynamo as early as 4.2 billion years (Ga) ago. However, our combined paleomagnetic, geochemical, and mineralogical studies on Jack Hills zircons indicate that most have poor magnetic recording properties and secondary magnetization carriers that postdate the formation of the zircons. Therefore, the existence of the geodynamo before 3.5 Ga ago remains unknown.