Iodine in Carbonate as a proxy for modern and ancient hypoxia


Oceanic Anoxic Events



Periods of globally distributed extreme oxygen depletion, so-called oceanic anoxic events (OAEs), have been recognized in the Mesozoic geological record and appear to be characteristic of episodes of extreme warmth. A new proxy, I/Ca ratios, in carbonates may be used to monitor seawater oxidation levels throughout Earth history.

Cenomanian
Toarcian



Paleocene-Eocene Thermal Maximum (PETM)


Anthropogenic global warming affects marine ecosystems in complex ways, among which the loss of dissolved oxygen emerges as a growing concern. Information from past events may help in forecasting future ocean deoxygenation. In geological records, the PETM at ~55.5 Ma, may represent the best analogue for modern global warming. I apply a novel paleo-redox proxy, iodine to calcium ratios in foraminiferal tests, to detect potentially subtle deoxygenation during the PETM.   
Forams
Foram closeup



Otolith


Images from Karin Limburg

A matched pair of juvenile winter flounder otoliths from Long Island Sound. 

Otolith Project slide 2


Details of core regions prior to ablation. Left Otolith closeup




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Forams