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Updated: Feb 7, 2026
11:49
Quantitative and Temporal Control of Oxygen Microenvironment at the Single Islet Level
Published on: November 17, 2013
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Constraints on Paleoproterozoic atmospheric oxygen levels
Eric J Bellefroid1, Ashleigh V S Hood2, Paul F Hoffman3
1Department of Geology and Geophysics, Yale University, New Haven, CT 06511; eric.bellefroid@yale.edu paulfhoffman@gmail.com.
Summary
Precambrian atmospheric oxygen levels were low, around 0.1% of modern levels. This research used carbonate cerium anomalies to estimate ancient oxygen partial pressures (pO2).
Area of Science:
- Geochemistry
- Paleoclimatology
- Biogeochemical Cycles
Background:
- Earth's oxygenation profoundly impacted life and geochemical cycles.
- Estimates of Precambrian atmospheric oxygen partial pressures (pO2) are highly debated.
- Cerium anomalies in carbonates (Ce/Ce*) offer a potential quantitative proxy for ancient pO2.
Purpose of the Study:
- To evaluate carbonate cerium anomalies as a quantitative proxy for atmospheric pO2.
- To estimate Proterozoic atmospheric pO2 using marine carbonates from the Paleoproterozoic Pethei Group.
- To constrain Paleoproterozoic atmospheric pO2 1.87 billion years ago.
Main Methods:
- Measured Ce/Ce* anomalies in marine carbonate precipitates across a depth gradient.
- Utilized detailed sedimentology and stratigraphy to determine paleo-depth.
- Applied a cerium oxidation model to quantitative atmospheric pO2 constraints.
Main Results:
- Minor depleted Ce anomalies were observed, primarily in platform and upper slope facies.
- Quantitative constraints suggest Paleoproterozoic atmospheric oxygen was low, near 0.1% of present levels.
- Empirical evidence supports low oxygen levels post-Lomagundi Event.
Conclusions:
- Paleoproterozoic atmospheric oxygen concentrations were significantly low.
- Low oxygen levels persisted through much of the Proterozoic.
- These conditions influenced the ecology of early complex organisms.
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