Interpretation of the Crustal Structure Around the Northern Viking Graben Based on Recent Seismic Data: Assessment of Previous Models

Abstract:

The understanding of the crustal structure of the northern North Sea was significantly improved with the acquisition of the deep seismic reflection profiles of the BIRPS project during the 1980’s. Some of those profiles have been interpreted by various authors, with interpretations that can differ considerably from each other.

Improvement in the seismic imaging of recent surveys allows the observation of more structures at the crustal scale. The reflective lower crust is observed both in 2D and 3D surveys, but the reflection and nature of the top of the crystalline basement remains elusive in the seismic over extensive areas. The use of potential field data is key to constrain the basement interpretation.

The region has experienced multiple extensional events. Steeply dipping faults are correlated with the latest rifting episode in the northern North Sea (Middle Jurassic – Early Cretaceous), while other structures could be structures associated with the previous Permian-Triassic rifting or other pre-existing features.

The faults extend to different levels of the crust, with different detachment levels recognized also in previous works. In the recent seismic, the top of the reflective lower crust appears to be another important detachment level. The presence and geometry of faults that seem to cut the entire crust would rule out some of the previous models.