| Summary: | Present estimates of the biogeochemical cycles of calcium, strontium, and potassium in the ocean reveal large imbalances between known input and output fluxes. Using pore fluid, incubation, and solid sediment data from North Pacific multi-corer cores we show that, contrary to the common paradigm, the top centimeters of abyssal sediments can be an active site of authigenic precipitation of clay minerals. In this region, clay authigenesis is the dominant sink for potassium and strontium and consumes nearly all calcium released from benthic dissolution of calcium carbonates. These observations support the idea that clay authigenesis occurring over broad regions of the world ocean may be a major buffer for ocean chemistry on the time scale of the ocean overturning circulation, and key to the long-term stability of Earth's climate. This study was funded by a Blavatnik postdoctoral fellowship to ZS, an Isaac Newton Trust grant to AVT and ZS, ERC StG 307582 (CARBONSINK) to AVT, and DFG Grant 458035111 to ZS. The cruise on-board RV Kilo Moana was funded by NSF Ocean Acidification Grant OCE1220600. We thank Gilad Antler for assisting with sample processing during CDisK-IV, Abby Lunstrum for analyzing particulate inorganic carbon, Christopher Jeans for discussions about clay minerals, Laura Healy for support with the particle size analyses, Harold Bradbury for support with the TIMS and Mervyn Greaves for support with the ICP-OES. Open Access funding enabled and organized by Projekt DEAL.
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