Editor's Summary

13 September 2007

Taking the Earth's pulse

The mechanism of formation of the Earth's continental crust and its timing — did it all form early in Earth's history, grow gradually, or in large pulses — have proven difficult to pin down. Pearson et al. have analysed large numbers of osmium alloy grains in order to quantify the distribution of ages at which melt was extracted from the Earth's mantle. They find that the ages are not evenly distributed but cluster in distinct periods, around 1.2, 1.9 and 2.7 billion years ago, coinciding with peaks in the ages of continental crust. This supports the theory that continental growth occurred in pulses linked to large-scale mantle melting events.

Letter: A link between large mantle melting events and continent growth seen in osmium isotopes

D. G. Pearson, S. W. Parman & G. M. Nowell

doi:10.1038/nature06122

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