Reevaluating the evidence for a Hadean-Eoarchean dynamo

Cauê S Borlina; Benjamin P Weiss; Eduardo A Lima; Fengzai Tang; Richard J M Taylor; Joshua F Einsle; Richard J Harrison; Roger R Fu; Elizabeth A Bell; Ellen W Alexander; Heather M Kirkpatrick; Matthew M Wielicki; T Mark Harrison; Jahandar Ramezani; Adam C Maloof

doi:10.1126/sciadv.aav9634

Reevaluating the evidence for a Hadean-Eoarchean dynamo

Sci Adv. 2020 Apr 8;6(15):eaav9634. doi: 10.1126/sciadv.aav9634. eCollection 2020 Apr.

Authors

Cauê S Borlina¹, Benjamin P Weiss¹, Eduardo A Lima¹, Fengzai Tang², Richard J M Taylor², Joshua F Einsle^{2

3

4}, Richard J Harrison², Roger R Fu⁵, Elizabeth A Bell⁶, Ellen W Alexander⁶, Heather M Kirkpatrick⁶, Matthew M Wielicki⁷, T Mark Harrison⁶, Jahandar Ramezani¹, Adam C Maloof⁸

Affiliations

¹ Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
² Department of Earth Sciences, University of Cambridge, Cambridge, UK.
³ Department of Materials Science and Metallurgy, University of Cambridge, Cambridge, UK.
⁴ Department of Earth Science and Engineering, Imperial College London, London, UK.
⁵ Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA.
⁶ Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, Los Angeles, CA, USA.
⁷ Department of Geological Sciences, University of Alabama, Tuscaloosa, AL, USA.
⁸ Department of Geosciences, Princeton University, Princeton, NJ, USA.

Abstract

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.

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