Occurrence and depositional environment of the Lower Cretaceous sands in the southern Witch Ground Graben

Lower Cretaceous sands in the southern Witch Ground Graben are of Aptian-Albian age and are part of the Sola Formation. In the Witch Ground Graben the Sola Formation is generally argillaceous. However, in the southern Witch Ground Graben, thick sands are developed and the argillaceous Sola Formation is replaced, almost in its entirety, by the sandy Kopervik Formation, also called the ‘Bosun Sands’. The increased clastic input in the upper part of the Lower Cretaceous is associated with the regression in the Central North Sea as a result of the Austrian tectonism. The sands of the Kopervik Formation are derived from sources on locally exposed and rotated fault blocks and emergent terraces and are deposited as submarine fan or turbiditic sands.