The Jurassic-Cretaceous North Sea Rift Dome and Associated Basin Evolution

Ole Graversen
University of Copenhagen, DK-1350 Copenhagen K, Denmark

The Middle-Late Jurassic North Sea Rift Dome was established by recognition of the near base Middle Jurassic erosional unconformity in the central North Sea. The distribution and range of the overlying hiatus illustrates the gross outline and duration of the exposed dome. The presence of Upper Jurassic deposits both in the central rifts and in the marginal troughs in the Sole Pit Basin and along the Tornquist Zone documents that the dome continued across the entire North Sea Basin. In addition, thick Lower Jurassic Series preserved beyond the erosional hiatus along the dome margins, suggests that the dome may have been initiated already in the Early Jurassic. The dome raised above sea-level during the Middle Jurassic, and deflation of the dome associated with rifting took place during the Late Jurassic. Lower Cretaceous sequences onlap the Central Graben footwall blocks, and this relationship has been interpreted to illustrate that post-rift basin infilling was initiated in the Cretaceous. However, regional isopach maps illustrates that the Jurassic rift system down through the Viking Graben-Central Graben was continued in the Cretaceous. In addition, the marginal basins down the dome flanks indicates that the Jurassic dome continued through the Cretaceous across the entire North Sea Basin between the Sole Pit Basin to the west and the Egersund Basin and the Norwegian-Danish Basin to the east; the sea-level was high, and the dome remained below sea-level. Post-rift subsidence was not attained untill the Tertiary as documented by Cenozoic basin subsidence centred above the central North Sea rifts.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005