I/Ca evidence for upper ocean deoxygenation during the PETM

Xiaoli Zhou, Ellen Thomas, Rosalind E.M. Rickaby, Arne M.E. Winguth, Zunli Lu

Research output: Contribution to journalArticle

35 Scopus citations

Abstract

Anthropogenic global warming affects marine ecosystems in complex ways, and declining ocean oxygenation is a growing concern. Forecasting the geographical and bathymetric extent, rate, and intensity of future deoxygenation and its effects on oceanic biota, however, remains highly challenging because of the complex feedbacks in the Earth-ocean biota system. Information on past global warming events such as the Paleocene-Eocene Thermal Maximum (PETM, ~55.5Ma), a potential analog for present and future global warming, may help in such forecasting. Documenting past ocean deoxygenation, however, is hampered by the lack of sensitive proxies for past oceanic oxygen levels throughout the water column. As yet no evidence has been presented for pervasive deoxygenation in the upper water column through expansion of oxygen minimum zones (OMZs). We apply a novel proxy for paleoredox conditions, the iodine to calcium ratio (I/Ca) in bulk coarse fraction sediment and planktonic foraminiferal tests from pelagic sites in different oceans, and compared our reconstruction with modeled oxygen levels. The reconstructed iodate gradients indicate that deoxygenation occurred in the upper water column in the Atlantic, Indian Oceans, and possibly the Pacific Ocean, as well during the PETM, due to vertical and potentially lateral expansion of OMZs. Key Points Foraminiferal I/Ca may be a useful paleoceanographic proxyOur I/Ca records demonstrate that OMZs expanded during the PETM

Original languageEnglish (US)
Pages (from-to)964-975
Number of pages12
JournalPaleoceanography
Volume29
Issue number10
DOIs
StatePublished - Oct 1 2014

Keywords

  • I/Ca
  • PETM
  • foraminifera
  • ocean deoxygenation

ASJC Scopus subject areas

  • Oceanography
  • Palaeontology

Fingerprint Dive into the research topics of 'I/Ca evidence for upper ocean deoxygenation during the PETM'. Together they form a unique fingerprint.

  • Cite this

    Zhou, X., Thomas, E., Rickaby, R. E. M., Winguth, A. M. E., & Lu, Z. (2014). I/Ca evidence for upper ocean deoxygenation during the PETM. Paleoceanography, 29(10), 964-975. https://doi.org/10.1002/2014PA002702