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

The mid-Norwegian Voring margin bounding the northern Atlantic underwent se veral rift episodes after the Caledonian orogeny. Permo-Triassic extension concentrated at the eastern inner margin, followed by Jurassic-Cretaceous e xtension at the center of the margin. Finally, more westward, the last rift episode led to continental breakup in the earliest Eocene. Although the ge neral architecture of the margin may be clear, the timing and distribution of particularly the oldest rift structures are poorly constrained. We use t wo-dimensional forward tectonostratigraphic modeling for better quantitativ e understanding of the tectonic evolution of the margin. Two regional profi les crossing the margin have been analyzed. Modeling of the two profiles in tegrates the basin shape and fill as well as the underlying crustal structu re of the margin. The modeling allows us (1) to quantify the distribution a nd timing of extension of subsequent rift episodes, (2) to predict the basi n and crustal architecture at deep levels, and (3) to test different interp retations of the seismic data. The level of lithospheric necking during bas in 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 lithospheric 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.