Intensified biogeodynamical carbon cycling by subduction controlled early Earth glaciations and oxygenation

Earth experienced intensified subduction on a global scale at the Archean–Proterozoic transition (~2.5 ± 0.3 Ga), closely followed by the Great Oxidation Event and the Huronian glaciations. Yet the relationship between the intensified subduction and these environmental transitions has remained unclear, especially given the extreme paucity of early rock records. Here we identify high δ7Li and low δ26Mg signatures in ~2.5 Ga arc basalts, providing the direct evidence that subducted carbonated rocks underwent efficient fluid-driven decarbonation during the Neoarchean. Geodynamic-thermodynamic modeling shows that Neoarchean flat, hot subduction released nearly all slab carbonates, while refractory organic carbon was transported into the deep mantle. This dichotomy—shallow carbonate degassing versus deep organic carbon burial—accelerated atmospheric oxygen accumulation, perturbed the CO2–CH4 balance, and was sufficient to drive planetary-scale climate fluctuations. We propose that the intensification of Neoarchean subduction carbon cycling directly triggered the earliest oxidation and glaciation events, underscoring biogeodynamical carbon cycling by subduction as Earth’s unique engine of habitability evolution.