Proterozoic Atmospheric Oxygen Levels

Noah Planavsky, Yale University, Department of Geology and Geophysics, New Haven, CT, United States, Christopher T. Reinhard, Georgia Institute of Technology, School of Earth & Atmospheric Sciences, Atlanta, United States, Xiangli Shaun Wang, Yale University, New Haven, CT, United States and Timothy Lyons, University of California Riverside, Earth and Planetary Sciences, Riverside, CA, United States

Contact First Author: Noah Planavsky; noah.planavsky@yale.edu

Previously Published Material: A portion of this reasearch was publisehd in Science in 2014.

Abstract ID#: 36802

 

English Abstract:
The oxygenation of Earth’s surface fundamentally altered global biogeochemical cycles and ultimately paved the way for the rise of metazoans at the end-Proterozoic. However, current estimates for atmospheric O2 levels during the billion years leading up to this time vary widely. Based on Cr isotope data from a suite of Proterozoic sediments from China, Australia and North America, interpreted in the context of data from similar depositional environments from Phanerozoic time, we find evidence for inhibited Earth surface Cr oxidation in the mid-Proterozoic (1.8 to 0.8 billion years ago). These data suggest that atmospheric oxygen levels were at most 0.1% of present atmospheric levels. Direct evidence for such low O2 concentrations in the Proterozoic helps explain the late emergence and diversification of metazoans.
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