Enhanced East Pacific Rise hydrothermal activity during the last two glacial terminations

Science  29 Jan 2016:
Vol. 351, Issue 6272, pp. 478-482
DOI: 10.1126/science.aad4296

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Searching sediment for climate signals

Sediments on the ocean floor may provide clues about the interplay between ice ages and mid-ocean ridge magma production. Lund et al. present well-dated and detailed sediment records from hydrothermal activity along the East Pacific Rise. The sediments show changes in metal fluxes that are tied to the past two glaciations. Ice age changes in sea level alter magma production, which is manifested by changes in hydrothermal systems. The apparent increase in hydrothermal activity at the East Pacific Rise around the past two glacial terminations suggests some role in moderating the size of ice sheets.

Science, this issue p. 478


Mid-ocean ridge magmatism is driven by seafloor spreading and decompression melting of the upper mantle. Melt production is apparently modulated by glacial-interglacial changes in sea level, raising the possibility that magmatic flux acts as a negative feedback on ice-sheet size. The timing of melt variability is poorly constrained, however, precluding a clear link between ridge magmatism and Pleistocene climate transitions. Here we present well-dated sedimentary records from the East Pacific Rise that show evidence of enhanced hydrothermal activity during the last two glacial terminations. We suggest that glacial maxima and lowering of sea level caused anomalous melting in the upper mantle and that the subsequent magmatic anomalies promoted deglaciation through the release of mantle heat and carbon at mid-ocean ridges.

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