Development of the North Viking Graben: inferences from laboratory modelling

Abstract

The North Viking Graben is a classic sedimentary basin in the North Sea that has been thoroughly studied over the last decade. Despite the amount and quality of seismic and well data now available, the processes of extension remain unclear and the relationship between sedimentation and deformation is still a matter of debate. We present the results of small-scale laboratory modelling. The models are made with sand and silicone putty to simulate brittle and ductile behaviour on a crustal scale. The experiments were designed to study the effects of: (a) the degree of coupling between brittle and ductile layers; (b) the obliquity of extension; and (c) the reactivation of inherited crustal-scale structures. The results are used to discuss the symmetry of extensional processes on crustal and lithospheric scales, as well as the relationship between sedimentation and deformation. It is proposed that the asymmetry of faulting in the upper crust and the nearly symmetric thinning of the whole crust are not mutually exclusive. A model involving nearly pure shear on the lithospheric scale is used to explain the development of an asymmetrical basin at shallow level. In addition, this model accounts for the nearly horizontal stratification of Lower Cretaceous sediments, the basal Cretaceous unconformity which caps many of the normal faults, and the localization of deformation to the west of the graben during the Lower Cretaceous.