The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Daniel Conley

Daniel Conley

Professor

Daniel Conley

Constraints on Earth System Functioning at the Paleocene-Eocene Thermal Maximum From the Marine Silicon Cycle

Author

  • Guillaume Fontorbe
  • Patrick J. Frings
  • Christina L. De La Rocha
  • Katharine R. Hendry
  • Daniel J. Conley

Summary, in English

The Paleocene-Eocene Thermal Maximum (PETM, ca. 56 Ma) is marked by a negative carbon isotope excursion (CIE) and increased global temperatures. The CIE is thought to result from the release of 13C-depleted carbon, although the source(s) of carbon and triggers for its release, its rate of release, and the mechanisms by which the Earth system recovered are all debated. Many of the proposed mechanisms for the onset and recovery phases of the PETM make testable predictions about the marine silica cycle, making silicon isotope records a promising tool to address open questions about the PETM. We analyzed silicon isotope ratios (δ30Si) in radiolarian tests and sponge spicules from the Western North Atlantic (ODP Site 1051) across the PETM. Radiolarian δ30Si decreases by 0.6‰ from a background of 1‰ coeval with the CIE, while sponge δ30Si remains consistent at 0.2‰. Using a box model to test the Si cycle response to various scenarios, we find the data are best explained by a weak silicate weathering feedback, implying the recovery was mostly driven by nondiatom organic carbon burial, the other major long-term carbon sink. We find no resolvable evidence for a volcanic trigger for carbon release, or for a change in regional oceanography. Better understanding of radiolarian Si isotope fractionation and more Si isotope records spanning the PETM are needed to confirm the global validity of these conclusions, but they highlight how the coupling between the silica and carbon cycles can be exploited to yield insight into the functioning of the Earth system.

Department/s

  • Quaternary Sciences

Publishing year

2020-05

Language

English

Publication/Series

Paleoceanography and Paleoclimatology

Volume

35

Issue

5

Document type

Journal article

Publisher

Wiley-Blackwell

Topic

  • Physical Geography

Keywords

  • Paleocene-Eocene Thermal Maximum
  • silicon biogeochemical cycle
  • silicon isotopes
  • weathering

Status

Published

ISBN/ISSN/Other

  • ISSN: 2572-4517