Scientific debate over Earth oxygenation theory

Researchers from the California Institute of Technology have challenged long-standing scientific theories regarding the timing and nature of Earth’s ancient atmospheric oxygenation. For decades, carbon-isotope signatures in rocks dating back 2 billion years were interpreted as evidence of a global chemical transformation that allowed oxygen to accumulate in the atmosphere.

New analysis of the Zaonega Formation in Karelia, Russia, suggests these isotopic signals may instead be the result of localized geological phenomena. By using in situ extraction to analyze gases trapped in microscopic rock pores, the team identified methane and propane with light carbon isotope ratios. This signature is likely caused by magma intruding into sedimentary basins, heating organic matter and releasing gases, rather than representing a planetwide decline in organic carbon.

Lead author Dr. Nivedita Thiagarajan noted that these processes mirror those seen in modern oil and gas basins, suggesting the event was not a global catastrophe. The research team plans to further test this theory by examining drill cores from the Francevillian Basin in Gabon.