Extensive crustal extraction in Earth’s early history inferred from molybdenum isotopes
McCoy-West, Alex J
Burton, Kevin W
Nowell, Geoff M
Fitton, J Godfrey
Kerr, Andrew C
Cawood, Peter A
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McCoy-West, A. J., Chowdhury, P., Burton, K. W., Sossi, P., Nowell, G. M., Fitton, J. G., Kerr, A. C., et al. (2019). Extensive crustal extraction in Earth’s early history inferred from molybdenum isotopes. Nature Geoscience https://doi.org/10.1038/s41561-019-0451-2
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.
This project was funded by a European Research Council Starting Grant (‘HabitablePlanet’ 306655) to H.M.W. and a NERC Grant (NE/M0003/1) to K.W.B. While at Monash A.J.M.-W., P.C. and P.A.C. were supported by ARC grant FL160100168.
EC FP7 ERC CONSOLIDATOR GRANT (306655)
NERC (via Durham University) (NE/M000303/1)
External DOI: https://doi.org/10.1038/s41561-019-0451-2
This record's URL: https://www.repository.cam.ac.uk/handle/1810/297108
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