Selenium (Se) is one of the key trace elements required by all animal and most plant life, and Se deficiencies in the food chain cause pathologies or death. Here we show from new geochemical analyses of trace elements in Phanerozoic marine pyrite that sustained periods of severe Se depletion in the past oceans correlate closely with three major mass extinction events, at the end of the Ordovician, Devonian and Triassic periods. These represent periods of Se depletion >1.5–2 orders of magnitude lower than current ocean abundances, being within the range to cause severe pathological damage in extant Se-reliant organisms. Se depletion may have been one of several factors in these complex extinction scenarios. Recovery from the depletion/extinction events is likely part of a natural marine cycle, although rapid rises in global oxygen from sudden major increases in marine productivity and plant biomass after each extinction event may also have played a crucial role.

Item Type:	Refereed Article
Keywords:	trace elements, geochemistry; oceans; mass extinctions
Research Division:	Earth Sciences
Research Group:	Geochemistry
Research Field:	Inorganic Geochemistry
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Earth Sciences
Author:	Large, RR (Professor Ross Large)
Author:	Danyushevsky, LV (Professor Leonid Danyushevsky)
Author:	Halpin, JA (Dr Jacqueline Halpin)
Author:	Lottermoser, B (Professor Bernd Lottermoser)
ID Code:	104167
Year Published:	2016
Funding Support:	Australian Research Council (DP150102578)
Web of Science® Times Cited:	17
Deposited By:	Earth Sciences
Deposited On:	2015-11-03
Last Modified:	2017-11-02
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