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Reevaluating the evidence for a Hadean-Eoarchean dynamo.

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.

SUBMITTER: Borlina CS

PROVIDER: S-EPMC7141829 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Reevaluating the evidence for a Hadean-Eoarchean dynamo.

Borlina Cauê S CS Weiss Benjamin P BP Lima Eduardo A EA Tang Fengzai F Taylor Richard J M RJM Einsle Joshua F JF Harrison Richard J RJ Fu Roger R RR Bell Elizabeth A EA Alexander Ellen W EW Kirkpatrick Heather M HM Wielicki Matthew M MM Harrison T Mark TM Ramezani Jahandar J Maloof Adam C AC

Science advances 20200408 15

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 magnetizati ...[more]

PMID: 32284988

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