ENVIRONMENTAL-IMPACT OF VOLCANIC MARGIN FORMATION

Late rift stage uplift and subsequent massive, transient volcanism during breakup of rifted volcanic continental margins constrain paleoenvironments by modifying basin geometry and the composition of the atmosphere, hydrosphere and thus biosphere on regional and global scales. The early Tertiary North Atlantic breakup history shows that lava emplacement was accompanied by regional ashfalls, and that extrusive complexes influenced Paleogene oceanic and continental margin circulation and sedimentation. Temporal correspondence with the terminal Paleocene deep-sea extinction event and the earliest Eocene greenhouse suggests a global impact, possibly by enhanced atmospheric CO2 levels, leading to polar warming and thereby changing patterns of deep-water formation. In this context, transient subaerial volcanism at continental margins should be considered with the much discussed continental flood basalt provinces and oceanic plateaus.