Three-dimensional crustal structure of the Vøring Margin (NE Atlantic): a combined seismic and gravity image

The three-dimensional (3-D) crustal structure of the Vøring Margin is investigated by integrating results from reflection and wide-angle seismic data, well log data, and 3-D gravity modeling. The reduced "crustal" Bouguer anomaly, obtained after computing the gravity effects of the water layer and Cenozoic and Cretaceous sedimentary cover, displays an arcuate-shaped gravity high that coincides with the Cretaceous subbasins. The Pre-Cretaceous layer varies in thickness from 7 to 8 km below the Vøring Marginal High to <2 km in the Mesozoic depocenters and is overlying a relative "high-density" upper-middle crust (2850 kg m^-3). Underlying the upper-middle crust, there is a "high-velocity/density" body, which is imaged along the Marginal High and western region of the Vøring Basin. The High Velocity Body shallows to <14 km depth in the western end of the Marginal High and thins out toward the eastern and southeastern regions of the basin. Regions of thick crust (∼24 km) are located in the eastern and southern parts of the basin and northern and central parts of the Marginal High, whereas thinner crust is observed at the southwest region of the study area (∼16 km) and in the Fenris Graben region and Utgard High (∼18 km). Residual gravity anomalies are related to the distribution of interbedded volcanics and to the presence of sedimentary subbasins under the Marginal High. Crustal thinning is not directly related to thickening of the HVB and/or the location of Cretaceous depocentres, indicating a major rejuvenation of the Cretaceous Moho related to the Maastritchian-Paleocene rifting episode and massive emplacement of igneous material during breakup.