Calcium isotope ratios of malformed foraminifera reveal biocalcification stress preceded Oceanic Anoxic Event 2

Gabriella D. Kitch*, Andrew Darin Jacobson, Bradley B. Sageman, Rodolfo Coccioni, Tia Chung-Swanson, Meagan E. Ankney, Matthew T. Hurtgen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Ocean acidification causes biocalcification stress. The calcium isotope composition of carbonate producers can archive such stress because calcium isotope fractionation is sensitive to precipitation rate. Here, we synthesize morphometric observations of planktic foraminifera with multi-archive calcium isotope records from Gubbio, Italy and the Western Interior Seaway spanning Cretaceous Ocean Anoxic Event 2 (~94 million years ago). Calcium isotope ratios increase ~60 thousand years prior to the event. The increase coincides with foraminiferal abnormalities and correlates with existing proxy records for carbon dioxide release during large igneous province volcanism. The results highlight Ocean Anoxic Event 2 as a geologic ocean acidification analog. Moreover, decreasing calcium isotope ratios during the event provide evidence for ocean alkalinization, which could have shifted air-sea carbon dioxide partitioning. These data offer an explanation for the Plenus Cold Event and further have implications for refining ocean alkalinity enhancement, a leading anthropogenic carbon dioxide removal strategy.

Original languageEnglish (US)
Article number315
JournalCommunications Earth and Environment
Volume3
Issue number1
DOIs
StatePublished - Dec 2022

ASJC Scopus subject areas

  • General Environmental Science
  • General Earth and Planetary Sciences

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