Oceanic plateaus represent large areas ∼1 × 106 km2) of thickened oceanic crust formed from rapidly erupted lava (<3 Myr). These plateaus have formed throughout most of geological time. They generally correlate with periods of environmental catastrophe characterised by oceanic anoxia, leading to black shale formation and mass extinction events. Such correlations are particularly evident in the Cretaceous and can be partly attributed to the release of CO2 during oceanic plateau formation, which ultimately resulted in a runaway greenhouse effect. Additionally, sea level rise and disruption of oceanic circulation patterns by displacement of seawater during plateau formation contributed to increased environmental stress and biotic extinction.