Interpretation of new data from the southwestern part of the Barents Sea makes it possible to refine earlier tectonic models. Following what was probably a Devonian and Early Carboniferous rifting phase, a stable platform was developed during the Carboniferous and Permian, with a north to south trending high, to the west. The north-northeast to south-southwest Senja left-lateral fault system was active in several phases through the Cretaceous and Tertiary, up to the Oligocene. This fault system caused complex deformation in the Senja Ridge and the Bjørnøya basin.