How Great Was the “Great Oxidation Event”?
Scientists found that chromium isotopes in Rio Tinto sediments suggest underestimated atmospheric oxygen levels during the Great Oxidation Event, indicating earlier support for animal life and a need for reevaluation of Earth's atmospheric history.
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scientists found that the chromium isotopes in the Rio Tinto sediments remained unfractionated, indicating a lack of the expected oxygen signal. This suggests that previous interpretations of chromium isotopes in ancient rocks may have underestimated atmospheric oxygen levels during the Great Oxidation Event (GOE). The GOE, occurring around 2.4 billion years ago, marked a significant increase in atmospheric oxygen due to the photosynthetic activity of early life forms. While traditional estimates suggested oxygen levels rose to 10%-40% of current levels, newer findings indicate that oxygen may have been present intermittently at levels sufficient to support early animal life much earlier than previously thought. The study of the Rio Tinto's extreme acidic conditions provides insights into how oxygen interacted with minerals and may help reconcile conflicting estimates of past oxygen levels. This research highlights the complexity of understanding Earth's atmospheric history and its implications for the evolution of life, suggesting that the timeline for the emergence of multicellular organisms may need to be reevaluated. The findings emphasize the need for further investigation into the geochemical processes that shaped early Earth's environment and the role of oxygen in the evolution of life.
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- Several users recommend resources, including books and documentaries, to learn more about Earth's history and the Great Oxidation Event.
- There is a discussion about the implications of atmospheric changes and the role of living organisms in maintaining oxygen levels.
- Some comments highlight the complexity of geological processes and the challenges in studying ancient Earth due to erosion and missing rock records.
- Users note the paradox of the Great Oxidation Event being both a significant evolutionary milestone and a mass extinction event.
- There are references to the broader impacts of oxygen on life and the environment, including its role in combustion and mineral formation.
16 commentsMy naive understanding was always that the earth or planets just sort of found a natural state of being after a while and were / are just that way now. It's very interesting to see the sea saw type scale of changes that occurred over time.
Absent any other evidence, this seems to suggest that the fractionation seen in today's sediments may be the result of processes occurring in seawater rather than in rivers, and if so, that would in turn suggest that what happens in rivers and estuaries is not a good guide to the fractionation we should see in ancient rocks, even if we assume ancient rivers were mostly like the Rio Tinto - unless the ancient seawaters were acidic enough to prevent fractionation occurring there.
Covers all the extinction events in Earths history in a way that would enthuse and educate laymen on this issue.
The fact that living organisms are responsible for something so large seems almost dumbfounding -- planets are big, atmospheres are big, and life is small; what is a pool of algae compared to a mountain, etc. But even such a basic thing as "the only reason we can have something as fundamental as FIRE is because of living things" is a bit of a mindblowing realization.
[1] probably not literally true; if you eliminated all life on earth then most of the O2 would probably be sequestered in oxides rather than remaining resident as CO2, but still. Although I guess a lot of non-living organic matter would eventually burn away as long as there is oxygen to support combustion.
https://www.atlasobscura.com/articles/great-unconformity-geo...
Anyone have recommendations for books about Earth's past?
https://eos.org/articles/metallic-nodules-create-oxygen-in-t....
I can wait for the next Great De-Oxidation Event, when mining companies are allowed to scoop up all these metals without any research.
> "I'm reminded of the Oxygen Catastrophe - https://en.wikipedia.org/wiki/Great_Oxidation_Event - we need oxygen to live, but it also kills."
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