Petrographic carbon in ancient sediments constrains Proterozoic Era atmospheric oxygen levels

Don E. Canfield*, Mark A. van Zuilen, Sami Nabhan, Christian J. Bjerrum, Shuichang Zhang, Huajian Wang, Xiaomei Wang

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


Oxygen concentration defines the chemical structure of Earth's ecosystems while it also fuels the metabolism of aerobic organisms. As different aerobes have different oxygen requirements, the evolution of oxygen levels through time has likely impacted both environmental chemistry and the history of life. Understanding the relationship between atmospheric oxygen levels, the chemical environment, and life, however, is hampered by uncertainties in the history of oxygen levels. We report over 5,700 Raman analyses of organic matter from nine geological formations spanning in time from 742 to 1,729 Ma. We find that organic matter was effectively oxidized during weathering and little was recycled into marine sediments. Indeed, during this time interval, organic matter was as efficiently oxidized during weathering as it is now. From these observations, we constrain minimum atmospheric oxygen levels to between 2 to 24% of present levels from the late Paleoproterozoic Era into the Neoproterozoic Era. Indeed, our results reveal that eukaryote evolution, including early animal evolution, was not likely hindered by oxygen through this time interval. Our results also show that due to efficient organic recycling during weathering, carbon cycle dynamics can be assessed directly from the sediment carbon record.

Original languageEnglish
Article numbere2101544118
JournalProceedings of the National Academy of Sciences (PNAS)
Issue number23
Number of pages8
Publication statusPublished - 8. Jun 2021

Bibliographical note

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  • Evolution
  • Graphite
  • Oxygen Proterozoic
  • Weathering


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