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. ORCID: https://orcid.org/0000-0001-5569-4730, Cawood, Peter A. and Williams, Helen M. 2019. Extensive crustal extraction in Earth’s early history inferred from molybdenum isotopes. Nature Geoscience 12 (11) , pp. 946-951. 10.1038/s41561-019-0451-2

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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.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Publisher:	Nature Research
ISSN:	1752-0894
Date of First Compliant Deposit:	17 September 2019
Date of Acceptance:	19 August 2019
Last Modified:	21 Nov 2024 18:30
URI:	https://orca.cardiff.ac.uk/id/eprint/125497

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