The Sørvestsnaget Basin is a major Cenozoic depocentre in the southwest Barents Sea. A relatively complete Paleocene - Middle Eocene succession is seen, including deposits of Early Paleocene (Danian) - Early Eocene, and Middle Eocene age. Deep marine conditions persisted throughout the Early Paleocene - Late Eocene, with emplacement of significant sandy submarine fans during the Middle Eocene. Deposits of Late Eocene - Late Miocene age are condensed, with several stratigraphic breaks. Significant marine shallowing took place at the Eocene - Oligocene boundary, and shallow marine conditions persisted throughout the Oligocene - Miocene. A thick wedge of Upper Pliocene - Pleistocene glacial erosion products truncates the older Cenozoic strata.
The Sørvestsnaget Basin is bounded to the west by the oceanic Lofoten Basin, and it's Cenozoic evolution is consequently affected by the opening of the Norwegian - Greenland Sea. The new well data, however, do not support earlier notions of widespread uplift in the Sørvestsnaget Basin associated with Early Eocene crustal break-up. However, a phase of differential subsidence and uplift between the Sørvestsnaget Basin and the flanking Veslemøy High/Senja Ridge occurred in the Early - Middle Eocene, and marine shallowing at the Eocene - Oligocene boundary may be coeval with a phase of tectonism induced by the plate tectonic movements.