Proxies for paleo-oxygenation: A downcore comparison between benthic foraminiferal surface porosity and I/Ca

Wanyi Lu, Catia F. Barbosa, Anthony E. Rathburn, Priscila da Matta Xavier, Anna P.S. Cruz, Ellen Thomas, Rosalind E.M. Rickaby, Yi Ge Zhang, Zunli Lu

Research output: Contribution to journalArticlepeer-review

Abstract

Benthic foraminiferal surface porosity (the mean percentage of surface area covered by pores; higher porosity: lower oxygenation) and iodine to calcium ratio (I/Ca, higher I/Ca: higher oxygenation) are both promising paleoceanographic proxies that will advance through testing in down-core studies. Here we report the first down-core comparison (~45 kyr) of these proxies for a core from the southern Brazilian margin (26°40.22′ S, 46°26.46′ W, 475 m water depth). Both proxies are most sensitive to low-O2 conditions (<50 μmol/kg), and not well-constrained at higher O2 concentrations. Porosity values are generally low (<15%) and I/Ca ranges between ~4 and ~ 6 μmol/mol throughout the core. The two proxies are overall consistent, suggesting that bottom-water oxygen concentrations at the site remained above 50 μmol/kg during the last 45 kyr. Several non-O2 factors (e.g., iodate reduction rates, water mass mixing, temperature, foraminiferal shell robustness) could influence the proxies and require further investigation.

Original languageEnglish (US)
Article number110588
JournalPalaeogeography, Palaeoclimatology, Palaeoecology
Volume579
DOIs
StatePublished - Oct 1 2021

Keywords

  • Benthic foraminifera
  • Bottom water
  • Iodine
  • Oxygen
  • Surface pores

ASJC Scopus subject areas

  • Oceanography
  • Ecology, Evolution, Behavior and Systematics
  • Earth-Surface Processes
  • Palaeontology

Fingerprint

Dive into the research topics of 'Proxies for paleo-oxygenation: A downcore comparison between benthic foraminiferal surface porosity and I/Ca'. Together they form a unique fingerprint.

Cite this