Upper limits on the extent of seafloor anoxia during the PETM from uranium isotopes

Abstract The Paleocene Eocene Thermal Maximum (PETM) represents a major carbon cycle and climate perturbation that was associated with ocean de-oxygenation, in qualitatively similar manner to the more extensive Mesozoic Oceanic Anoxic Events. Although indicators of de-oxygenation are common for PETM, linked biotic turnover, global extent temporal progression is poorly constrained. Here we present carbonate uranium isotope data PETM. A lack resolvable U-cycle during event suggests limited expansion seafloor anoxia on scale. We use this result, conjunction biogeochemical model, set an upper limit de-oxygenation. model new U data, whilst also being consistent plausible emission scenarios observations recovery, permit maximum ~10-fold anoxia, covering <2% area.