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The Kapp Toscana Group on the Barents Sea shelf is divided into two subgroups: the Storfjorden (Ladinian to Norian) and Realgrunnen (Early Norian to Bathonian).
The Storfjorden Subgroup consists of the Snadd Formation and is defined at the base of a 60m shale interval above the mixed lithologies of the Kobbe Formation. The upper boundary is defined at the basal shales of the Fruholmen Formation. In the reference wells (7120/12-1 and 7120/9-2) the thickness is 944m and 1410m respectively, while in the type well (7120/12-2) the thickness is only 573m due to faulting 400m of the middle and upper part of the unit. On the Loppa High, thicknesses are in the order of 1300-1400m. On the Nysleppen and Måsøy Fault the thickness is between 200 and 550m. The Bjarmeland Platform has thicknesses in the order of 600 to 850m. The basal grey shale coarsens up into shale interbedded with grey siltstones and sandstones. In the middle and lower parts of the unit, calcareous layers are relatively common, with thin coaly lenses occurring in the upper part. High rates of deposition occurred throughout the area with little differentiation between negative and positive elements. The Ladinian sequence represents relatively distal marine environments, following a major transgression which submerged all structural highs and platform areas. The Carnian is marked by a large scale progradation of deltaic systems derived from the south-southeast over the entire region. The upper part of the Storfjorden Subgroup has been eroded on the Finnmark Platform, but still more than 1000m have been drilled in the central parts (wells 7128/4-1 and 7128/6-1).