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Regulation of atmospheric oxygen during the Proterozoic

Authors :
Thomas A. Laakso
Daniel P. Schrag
Source :
Earth and Planetary Science Letters. 388:81-91
Publication Year :
2014
Publisher :
Elsevier BV, 2014.

Abstract

Many studies suggest that oxygen has remained near modern levels throughout the Phanerozoic, but was much less abundant from the “Great Oxygenation Event” around 2.4 Ga until the late Neoproterozoic around 600 Ma ( Kump, 2008 ). Using a simple model, we show that the maintenance of atmospheric pO2 at ∼1% of present atmospheric levels (PAL) is inconsistent with modern biogeochemical cycling of carbon, sulfur and iron unless new feedbacks are included. Low oxygen conditions are stable in our model if the flux of phosphorus to the oceans was greatly reduced during the Proterozoic. We propose a mechanism to reduce this flux through the scavenging of phosphate ions with an “iron trap” driven by greater surface mobility of ferrous iron in a low pO2 world. Incorporating this feedback leads to two stable equilibria for atmospheric oxygen, the first quantitative hypothesis to explain both Proterozoic and Phanerozoic O2 concentrations.

Details

ISSN :
0012821X
Volume :
388
Database :
OpenAIRE
Journal :
Earth and Planetary Science Letters
Accession number :
edsair.doi...........66272c19c6c60c8eacc9b82afdd973e4