A TECTONIC-MAGMATIC TRIGGER FOR EARLY CENOZOIC HYPERTHERMALS? (Invited Presentation)

The climate history of the early Cenozoic is distinguished by multiple short-lived warming events (hyperthermals) that followed large-scale addition of C-based greenhouse gases into the ocean-atmosphere system. Decomposition of submarine methane hydrate deposits, modulated by intervals of solar radiation maxima during orbital cycles, has been proposed as the cause of the gas release. On the other hand, the Paleocene Eocene Thermal Maximum (PETM), the largest of the Cenozoic hyperthermals, has also been attributed to an impacting comet or alternatively the venting of thermogenic CH₄, CO and CO₂ during large scale Iceland hotspot-related igneous activity in organic-rich continental sedimentary basins accompanying the opening of the NE Atlantic.

Formation of the NE Atlantic Igneous Province commenced around 62 Ma and continued throughout the Cenozoic. A shallow sheet of anomalously hot (Icelandic) asthenosphere has been inferred to have underlain much of the Greenland lithosphere during the Paleocene and early Eocene. Tectonic-magmatic (rift to drift) events on both the West and East Greenland margins are recorded by Paleocene and Early Eocene flood basalts, regional dike swarms, central intrusions and sill complexes in the feather-edge of several Paleozoic-Mesozoic continental margin rift basins that have been exposed by Tertiary uplift. Field observations in these basins testify as to how the magmatism invaded and heated organic-rich sediments, including former oil fields.

We combine new and published geochronological and geochemical data for tectonic-magmatic events recorded along the Greenland continental rifted margin to test the hypothesis that the origin of the hyperthermals, including the PETM, is rooted in plate tectonic, metamorphic and volcanic processes in the North Atlantic region.