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., and Williams, Helen M. (2019) Extensive crustal extraction in Earth’s early history inferred from molybdenum isotopes. Nature Geoscience, 12. pp. 946-951.

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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 ID: 64311
Item Type: Article (Research - C1)
ISSN: 1752-0908
Copyright Information: © The Author(s), under exclusive licence to Springer Nature Limited 2019
Funders: European Research Council (ERC), National Environment Research Council (NERC), Australian Research Council
Projects and Grants: ERC Starting Grant 306655 ‘‘Habitable Planet”, NERC Grant NE/M0003/1, ARC grant FL160100168
Date Deposited: 25 Nov 2020 23:42
FoR Codes: 04 EARTH SCIENCES > 0402 Geochemistry > 040203 Isotope Geochemistry @ 70%
04 EARTH SCIENCES > 0403 Geology > 040313 Tectonics @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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