🌋 An unexplained carbon cycle caused by major volcanic eruptions

The Lomagundi-Jatuli event, which occurred more than two billion years ago, followed the Great Oxygenation Event and was marked by a significant change in the isotopic composition of carbon. Its cause, however, remains uncertain.

Scientists from the CNRS Earth & Universe report lead isotope dating of black shales in Gabon at 2.194 billion years, linking the Lomagundi-Jatuli event, which occurred at approximately the same time, to the African super volcanic plume, known as the Birimian-Eburnean orogenic event, which produced very large volumes of oceanic basalt.


The massive release of carbon dioxide by volcanic eruptions would have exceeded the ocean's capacity to absorb it, far exceeding its buffering capacity. As a result, Earth's carbon and oxygen cycles were disrupted for between 100 and 200 million years. The unusual increase in the carbon isotope ratio in sedimentary carbonates, along with the expansion, at that time in Earth's history, of previously largely submerged continental exposures, indicates intensified weathering.

This process brought more nutrients to the ocean, stimulating marine primary production and promoting the burial of organic carbon.

According to the authors, the results suggest an explanation for the Lomagundi-Jatuli event and further indicate that the interaction of tectonic events and biogeochemical cycles may have paved the way for conditions favoring the emergence of the first eukaryotic life forms on Earth about 300 million years earlier than previously thought.