Cenozoic and late Mesozoic stratigraphy and subsidence history of the Norwegian margin
The stratigraphy of the passive continental margin off Norway is mapped, utilizing both Deep Sea Drilling Project (DSDP) data at five sites on the outer margin and multichannel seismic (MCS) data collected by Lamont-Doherty Geological Observatory. Distinct units in the acoustic stratigraphy are tied to biostratigraphic and lithostratigraphic units in the drill data and mapped throughout most of the margin. Stratigraphy of the pre–lower Eocene section not encountered in drilling is inferred from depositional patterns and correlation with the continental-shelf sequences, the stratigraphy of which has been developed independently from detailed surveys. The margin can be divided into three physiographic provinces: two broad shelf and slope regions separated by the Jan Mayen Fracture Zone, and the steep, narrow shelf and slope off the Lofoten Islands. Each experienced a separate Cenozoic subsidence history. The Voring Plateau is partly underlain by oceanic crust; it subsided nearly 1,000 m less than expected from thermal contraction, but it did so following the development of a relatively deep-water environment in the Paleocene. North of the Voring Plateau, the margin may have subsided a few hundred metres more than thermal studies had predicted. There is no evidence for a phase of extensional deformation associated with the inception of spreading. The youngest faulted level occurs at the Late Jurassic level, preceding sea-floor spreading by nearly 100 Ma, and deformation in the Cretaceous section is characterized by large uplift structures that may be of halokinetic origin. The physiographic provinces as well as the Cenozoic subsidence patterns along the margin appear to be related to the style and extent of Mesozoic basin development and tectonics along the margin.