Superdeep Diamonds Provide Evidence for a Melting Barrier to Deep Carbon Subduction

Carbon is cycled from Earth’s surface to its depths, emerging through the crust from volcanoes, and descending to the mantle in subducting ocean floor. But how far down is the carbon subducted? In a letter by Andrew Thomson, Michael Walter, Simon Kohn, and Richard Brooker (University of Bristol, UK) published in Nature, the authors propose that most carbon goes no deeper than about 300 to 500 kilometers, at which point a carbon barrier limits carbon recycling into the deeper mantle [1].

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