Polyphase rift evolution of the Vøring margin (mid-Norway): Constraints from forward tectonostratigraphic modeling

The mid-Norwegian Vøring margin bounding the northern Atlantic underwent several rift episodes after the Caledonian orogeny. Permo-Triassic extension concentrated at the eastern inner margin, followed by Jurassic-Cretaceous extension at the center of the margin. Finally, more westward, the last rift episode led to continental breakup in the earliest Eocene. Although the general architecture of the margin may be clear, the timing and distribution of particularly the oldest rift structures are poorly constrained. We use two-dimensional forward tectonostratigraphic modeling for better quantitative understanding of the tectonic evolution of the margin. Two regional profiles crossing the margin have been analyzed. Modeling of the two profiles integrates the basin shape and fill as well as the underlying crustal structure of the margin. The modeling allows us (1) to quantify the distribution and timing of extension of subsequent rift episodes, (2) to predict the basin and crustal architecture at deep levels, and (3) to test different interpretations of the seismic data. The level of lithospheric necking during basin formation is constrained by basement topography and Moho depth and lies within the middle crust (20 km). Furthermore, we investigate the migration of the rift axes and the elastic lithosperic strength during the different rift episodes. Locations of previous extension are not reactivated during renewed rifting. Instead, renewed rifting occurs preferentially in regions where the lithosphere has experienced less extension.