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Accretion of the Earth and segregation of its core

Naturevolume 441pages825833 (2006) | Download Citation

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Abstract

The Earth took 30–40 million years to accrete from smaller ‘planetesimals’. Many of these planetesimals had metallic iron cores and during growth of the Earth this metal re-equilibrated with the Earth's silicate mantle, extracting siderophile (‘iron-loving’) elements into the Earth's iron-rich core. The current composition of the mantle indicates that much of the re-equilibration took place in a deep (> 400 km) molten silicate layer, or ‘magma ocean’, and that conditions became more oxidizing with time as the Earth grew. The high-pressure nature of the core-forming process led to the Earth's core being richer in low-atomic-number elements, notably silicon and possibly oxygen, than the cores of the smaller planetesimal building blocks.

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Acknowledgements

The constructive reviews of C. Agee and K. Righter are acknowledged with thanks. B.J.W. acknowledges the award of an ARC Federation Fellowship.

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  1. Department of Earth and Planetary Sciences, Macquarie University, North Ryde, New South Wales, 2109, Australia

    • Bernard J. Wood
  2. Department of Earth Sciences, University of Bristol, Bristol, Queen's Road, BS8 1RJ, UK

    • Michael J. Walter
    •  & Jonathan Wade

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Correspondence to Bernard J. Wood.

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