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Daniel Conley

Daniel Conley

Professor

Daniel Conley

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

Författare

  • 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.

Avdelning/ar

  • Kvartärgeologi

Publiceringsår

2020-05

Språk

Engelska

Publikation/Tidskrift/Serie

Paleoceanography and Paleoclimatology

Volym

35

Issue

5

Dokumenttyp

Artikel i tidskrift

Förlag

Wiley-Blackwell

Ämne

  • Physical Geography

Nyckelord

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

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 2572-4517