Redox Recycling

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Science  14 Jun 2013:
Vol. 340, Issue 6138, pp. 1264
DOI: 10.1126/science.340.6138.1264-d

Plate tectonics drive the continuous exchange of material between Earth's crust and mantle. Subduction adds crustal materials to the mantle, which influence the composition of erupted lavas at mid-ocean ridges. Because chemical and physical processes in the mantle change over time as a response to the availability of oxygen, the redox state of mid-ocean ridge basalts may trace the history of recycling between crust and mantle. Cottrell and Kelley (p. 1314, published online 2 May) analyzed the relation between the oxidation state of iron in a global suite of mid-ocean ridge basalts and tracers for mantle source composition. Over tectonic time scales, the recycling of reduced carbon in ancient crustal sediments may result in the preservation of more reduced zones in the mantle.

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