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

McCoy-West, Alex J. and Chowdhury, Priyadarshi and Burton, Kevin W. and Sossi, Paolo and Nowell, Geoff M. and Fitton, J. Godfrey and Kerr, Andrew C. and 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. ISSN 1752-0894 DOI https://doi.org/10.1038/s41561-019-0451-2

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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
Uncontrolled Keywords: 2019AREP; IA75
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Journal or Publication Title: Nature Geoscience
Volume: 12
Page Range: pp. 946-951
Identification Number: https://doi.org/10.1038/s41561-019-0451-2
Depositing User: Sarah Humbert
Date Deposited: 15 Nov 2019 12:17
Last Modified: 15 Nov 2019 12:17
URI: http://eprints.esc.cam.ac.uk/id/eprint/4521

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