doi.org/10.1073/pnas.2512767123
Credibility: 989
#oxidation
Researchers have developed a new statistical model that sheds light on a major mystery in Earth’s ancient history
They showed that a significant increase in the ratio of carbon-13 to carbon-12 in ancient oceans, known as the Lomagundi-Jatuli Excursion, was smaller than previously thought and occurred around 2.45 billion years ago.
This period coincides exactly with the Great Oxidation Event, when the amount of oxygen in Earth’s atmosphere rose from virtually zero to levels capable of supporting more complex life forms.
At the same time, the planet underwent intense global glaciations.
For a long time, scientists observed an anomaly in ancient carbonate rocks formed at the bottom of prehistoric seas: a higher amount of carbon-13 than expected.
This indicated that something drastically altered the carbon cycle on Earth.
However, there was uncertainty about the true size of this peak, its exact timing, and how it related to the emergence of atmospheric oxygen.
The new model, created with few assumptions and analyzing global data from various sources, reveals that the increase in the proportion of carbon-13 was more modest and occurred earlier than previously thought.
Changes in the carbon cycle, including greater burial of carbon-13-rich carbonates, began at the same time that oxygen began to accumulate in the atmosphere and the planet faced global ice ages.
Before this event, single-celled photosynthetic organisms already produced oxygen and organic matter, but chemical reactions, such as those caused by volcanoes and rock weathering, consumed this oxygen rapidly, preventing its accumulation.
Over time, increased biological activity and changes in the carbon cycle favored the burial of organic carbon, allowing oxygen to escape into the atmosphere and accumulate.
This discovery improves our understanding of how the carbon cycle and the increase in oxygen were interconnected in Earth’s distant past.
It shows that major biogeochemical transformations occurred simultaneously, preparing the environment for the evolution of more complex, multicellular life.
The study highlights the rarity of planetary transitions like this in the universe and helps to unravel one of the most important chapters in the geological and biological history of our planet.
The research was led by Stacey Edmonsond, a doctoral student at the University of Victoria in Canada, in collaboration with Professor Blake Dyer, and published in the journal Proceedings of the National Academy of Sciences.
Published in 03/23/2026 01h30
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
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