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Extensive crustal extraction in Earth’s early history inferred from molybdenum isotopes

McCoy-West, Alex J.; Chowdhury, Priyadarshi; Burton, Kevin W.; Sossi, Paolo; Nowell, Geoff M.; Fitton, J. Godfrey; Kerr, Andrew C.; Cawood, Peter A.; Williams, Helen M.

Extensive crustal extraction in Earth’s early history inferred from molybdenum isotopes Thumbnail


Authors

Alex J. McCoy-West

Priyadarshi Chowdhury

Paolo Sossi

J. Godfrey Fitton

Andrew C. Kerr

Peter A. Cawood

Helen M. Williams



Abstract

Estimates of the volume of the earliest crust based on zircon ages and radiogenic isotopes remain equivocal. Stable isotope systems, such as molybdenum, have the potential to provide further constraints but remain underused due to the lack of complementarity between mantle and crustal reservoirs. Here we present molybdenum isotope data for Archaean komatiites and Phanerozoic komatiites and picrites and demonstrate that their mantle sources all possess subchondritic signatures complementary to the superchondritic continental crust. These results confirm that the present-day degree of mantle depletion was achieved by 3.5 billion years ago and that Earth has been in a steady state with respect to molybdenum recycling. Mass balance modelling shows that this early mantle depletion requires the extraction of a far greater volume of mafic-dominated protocrust than previously thought, more than twice the volume of the continental crust today, implying rapid crustal growth and destruction in the first billion years of Earth’s history.

Journal Article Type Article
Acceptance Date Aug 19, 2019
Online Publication Date Sep 23, 2019
Publication Date Dec 1, 2019
Deposit Date Sep 12, 2019
Publicly Available Date Mar 23, 2020
Journal Nature Geoscience
Print ISSN 1752-0894
Electronic ISSN 1752-0908
Publisher Nature Research
Peer Reviewed Peer Reviewed
Volume 12
Pages 946-951
DOI https://doi.org/10.1038/s41561-019-0451-2
Public URL https://durham-repository.worktribe.com/output/1322246

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