Increased export production during recovery from the Paleocene-Eocene thermal maximum constrained by sedimentary Ba isotopes

Bridgestock, Luke and Hsieh, Yu-Te and Porcelli, Donald and Henderson, Gideon M. (2019) Increased export production during recovery from the Paleocene-Eocene thermal maximum constrained by sedimentary Ba isotopes. Earth and Planetary Science Letters, 510. pp. 53-63. ISSN 0012 821X DOI

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The Paleocene-Eocene thermal maximum (PETM; similar to 56 Ma) was a transient global warming event associated with a huge perturbation to the global carbon cycle. Changes in marine biological productivity may have contributed to the rapid recovery from this climate change event, by driving the burial of inorganic and organic carbon. Disagreement between proxy reconstructions, however, makes the response of biological productivity to climatic changes experienced during the PETM uncertain. Accumulation of non-detrital barium (Ba) in marine sediments is a commonly used proxy for export production. This proxy however can be compromised by artifacts resulting from dilution and changes in barite preservation, issues that have been debated for its application to sediments deposited during the PETM. Here we present a new approach to address these limitations, by combining non-detrital Ba accumulation with Ba isotope data for marine PETM sediments. Observed positive correlation between these variables is consistent with their control by local changes in export production. These results help resolve previous discrepancies between productivity reconstructions, and indicate export production at sites in the Southern Ocean and South Atlantic decreased or remained unchanged following the PETM onset, followed by an increase to maximum values in the PETM recovery period. This increase in export production coincides with elevated carbonate accumulation rates, representing an important mode of carbon sequestration. These new constraints therefore support the idea that increased production and export of calcifying nannoplankton, perhaps driven by changes in ocean stratification and/or terrestrial runoff, played an important role in rapid recovery from the PETM. This work also demonstrates the utility of sedimentary Ba isotope compositions for understanding past changes in the marine carbon cycle. (C) 2019 Elsevier B.V. All rights reserved.

Item Type: Article
Uncontrolled Keywords: NILAREP
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Earth and Planetary Science Letters
Volume: 510
Page Range: pp. 53-63
Identification Number:
Depositing User: Sarah Humbert
Date Deposited: 05 Nov 2020 17:53
Last Modified: 25 Nov 2020 13:30

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