New compilation of top basement and basement thickness for the Norwegian continental shelf reveals the segmentation of the passive margin system

Abstract

Abstract We present the first complete top basement map for the passive margin system of the Norwegian continental shelf, which covers the Northern North Sea, the mid-Norwegian margin system, and the western Barents Sea. This compilation is based largely on a review and synthesis of previously published portions on detailed depth to basement and 3D modelling studies, which in turn are based on a wealth of seismic profiles, commercial and scientific drilling on the shelf and mainland Norway, petrophysical sampling and a dense coverage of gravity and aeromagnetic data. The top basement defines the base of the sedimentary strata. Sedimentary thickness is larger than 14 km on the mid-Norwegian margin and the Barents Sea, but varies strongly along the different segments of the margin. In the northeastern North Sea, the Danish–Norwegian Basin, and over the Trøndelag Platform the top basement does not exceed 8 km in depth. The top basement map highlights the transition between the different segments of the Norwegian margin, between different basement domains (e.g. Caledonian and Precambrian basement), and shows a clear correlation with the normal faults mapped on the margin and prolongated from onshore Norway into the offshore realm. The distribution of basement domains provides a new regional understanding of the evolution of the entire passive margin system. We also present an updated Moho depth compilation, which allows calculation of a thickness of crystalline basement map for the entire margin. The basement thickness map enhances differences in crustal architecture for the different margin segments and shows extremely thin crust (less than 12.5 km) for large areas on the mid-Norwegian margin and westernmost Barents Sea, intermediate thin crust (15–20 km) below the Viking Graben, but moderately thin crust (20–30 km) below the Norwegian–Danish Basin and the remaining part of the Barents Sea.