The geological history of the North Atlantic Ocean

The North Atlantic Ocean began to form about 130 million years (Ma) ago when sea-floor spreading, propagating from the south, caused Iberia and Newfoundland to separate. At that time, the crust beneath the region was stretching and subsiding to form sedimentary basins (including the North Sea). By —105 Ma, sea-floor spreading had extended into one of these basins, the Rockall Trough, and this continued until ~84 Ma. Spreading started again further west to form the Labrador Sea at -61 Ma, and then between Greenland and Scotland at ~56 Ma. Unlike the earlier rifting episodes, the final stage in the break-up of the
North Atlantic region was accompanied by the widespread eruption of basaltic magma. Two phases of magmatism are recognised: the first (62-58 Ma) predating the separation of Greenland from NW Europe, and the second (56-52 Ma) accompanying it. The sudden onset of volcanism at 62 Ma was due to the initiation of a convective plume of hot mantle, now located beneath Iceland. The products of the two volcanic phases are preserved as thick sequences of basaltic lava flows outcropping over an area extending from Baffin Island in the west, through West and East Greenland and the Faeroes, to Scotland in the east. The
second phase blanketed large parts of western Europe with volcanic ash layers that now form important stratigraphic marker horizons in the North Sea and surrounding areas, including Denmark and Great Britain. Initiation of the Iceland mantle plume caused regional uplift and may have influenced the final stages of continental break-up. Uplift led to erosion of the continental margins and the deposition of hydrocarbon-hosting sand bodies in the North Sea, and is also responsible for shaping the landscape of the Atlantic margins