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Cenozoic global cooling and increased seawater Mg/Ca via reduced reverse weathering

Author(s): Dunlea, Ann G; Murray, Richard W; Santiago Ramos, Danielle P; Higgins, John A

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Abstract: Authigenic clay minerals formed on or in the seafloor occur in every type of marine sediment. They are recognized to be a major sink of many elements in the ocean but are difficult to study directly due to dilution by detrital clay minerals. The extremely low dust fluxes and marine sedimentation rates in the South Pacific Gyre (SPG) provide a unique opportunity to examine relatively undiluted authigenic clay. Here, using Mg isotopes and element concentrations combined with multivariate statistical modeling, we fingerprint and quantify the abundance of authigenic clay within SPG sediment. Key reactants include volcanic ash (source of reactive aluminium) and reactive biogenic silica on or shallowly buried within the seafloor. Our results, together with previous studies, suggest that global reorganizations of biogenic silica burial over the Cenozoic reduced marine authigenic clay formation, contributing to the rise in seawater Mg/Ca and decline in atmospheric CO2 over the past 50 million years.
Publication Date: 10-Oct-2017
Citation: Dunlea, Ann G., Richard W. Murray, Danielle P. Santiago Ramos, and John A. Higgins. "Cenozoic global cooling and increased seawater Mg/Ca via reduced reverse weathering." Nature communications 8, no. 1 (2017): 844. DOI: 10.1038/s41467-017-00853-5.
DOI: DOI: 10.1038/s41467-017-00853-5
EISSN: 2041-1723
Pages: 1 - 7
Language: eng
Type of Material: Journal Article
Journal/Proceeding Title: Nature Communications
Version: Final published version. This is an open access article.

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