Early Tertiary magmatism in the offshore NW UK margin and surrounds

Abstract

The Iceland Plume, activated perhaps as early as Late Cretaceous time and extending through the Tertiary, was responsible for the generation of large volumes of igneous rocks, covering an area of roughly 2000 km in diameter, encompassing Greenland. the Vøring Basin, the Faeroes, the Faeroe–Shetland Basin, the Rockall Trough and NW Scotland. Within this large area, magmatism is mainly manifested as lava fields, sediment–sill complexes, and central or strato/shield type volcano complexes. Towards the continental margin of NW Europe, extrusive rocks occur m two distinct geographical areas. SW of the Munkagrunnur Ridge of the Faeroe Platform, lavas are mainly extruded radially from strato/shield volcano complexes. To the NE, in contrast, seismic evidence suggests that the tipper part of the Faeroe Plateau Lava Group extrusive originate from the same source that formed the Seaward Dipping Reflector Sequences NW of the Faeroes. Towards the SE of the Faeroes, the distribution of the Faeroe Plateau Lava Group (Upper. Middle and Lower Series) lavas is controlled by pre-existing structure and sea-level fluctuations, Seismic and well evidence confirms that, generally, the Upper Series extends furthest into the Faeroe–Shetland Basin while basaltic progradational units form the SE limit of the Lower Series. Similar structures of possibly the same age have been identified within the NE Rockall Trough. There appear to have been two major phases or pulses of Early Tertiary magmatism within the North Atlantic Igneous Province; an initial outburst at around 62 Ma and a later phase at around 55 Ma.