Extensional geometry of the Mid Norwegian Margin before Early Tertiary continental breakup

Abstract

Interpretation of reflection seismic data integrated with existing crustal models provide an interpretation of the deeply buried Mesozoic extensional geometry of the Vøring and Møre margins in the Norwegian Sea. Whereas Late Paleozoic to Triassic basins are limited by high angle normal faults with NW and SE dips, the Late Jurassic–Early Cretaceous Vøring and Møre basins are characterised by low-angle normal faults that dip towards the NW. Between the Vøring and Møre basins, at the SE end of the Jan Mayen Fracture Zone, a synthetic transfer zone is interpreted. Geometrical models based on basin and fault geometries show that the rift system detached near the upper crust–lower crust transition in the study area. This rift system accommodated between 110 and 140 km of post-Early Jurassic extension according to the geometry of the present-day pre-Cretaceous upper crust. A simple geometrical forward model suggests that a substantial part of this stretching occurred during the Late Cretaceous–Paleocene, thinning the central and NW segments of the Late Jurassic–Early Cretaceous rift.