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Terrestrial environmental change across the onset of the PETM and the associated impact on biomarker proxies: A cautionary tale

Research output: Contribution to journalArticle

Original languageEnglish
Article number102991
Number of pages8
JournalGlobal and Planetary Change
Volume181
Early online date21 Jul 2019
DOIs
DateAccepted/In press - 18 Jul 2019
DateE-pub ahead of print (current) - 21 Jul 2019
DatePublished - 1 Oct 2019

Abstract

The Paleocene-Eocene Thermal Maximum (PETM; ~ 56 million years ago) is the most severe carbon cycle perturbation event of the Cenozoic. Although the PETM is associated with warming in both the surface (up to 8°C) and deep ocean (up to 5°C), there are relatively few terrestrial temperature estimates from the onset of this interval. The associated response of the hydrological cycle during the PETM is also poorly constrained. Here, we use biomarker proxies (informed by models) to reconstruct temperature and hydrological change within the Cobham Lignite (UK) during the latest Paleocene and early PETM. Previous work at this site indicates warm terrestrial temperatures during the very latest Paleocene (ca. 22-26°C). However, biomarker temperature proxies imply cooling during the onset of the PETM (ca. 5-11°C cooling), inconsistent with other local, regional and global evidence. This coincides with an increase in pH (ca. 2 pH units with pH values > 7), enhanced waterlogging, a major reduction in fires and the development of areas of open water within a peatland environment. This profound change in hydrology and environment evidently biases biomarker temperature proxies, including the branched GDGT paleothermometer. This serves as a cautionary tale on the danger of attempting to interpret biomarker proxy records without a wider understanding of their environmental context.

    Research areas

  • Biomarkers, Eocene, GDGTs, Hydrology, Lignite, Peat

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    Rights statement: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Elsevier at https://doi.org/10.1016/j.gloplacha.2019.102991 . Please refer to any applicable terms of use of the publisher.

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    Embargo ends: 21/07/20

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    Licence: CC BY-NC-ND

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