Paul Mann and Alejandro Escalona

In order to explain the different structural styles and basins along the continental margin of Svalbard and the southern Barents Sea, we propose to apply the strike-slip paired bend hypothesis. This simple conceptual geologic model, based on a worldwide compilation of active continental and oceanic faults, predicts the simultaneous formation of a convergent, or restraining bend (200-km-long Svalbard fold-thrust belt), adjacent to a divergent, or releasing bend (200-km-long Vestbakken pull-apart basin). This simple geologic model can form the basis for kinematic analysis and modeling that can be applied to the petroleum potential basin formed in the Vestbakken basin. The presence of a paired bend embedded within the strike-slip continental margin is supported by regional gravity and magnetic maps. The paired bend can also be recognized from previous reconstructions as evolving as a linked convergent-divergent structure from evolved from late Cretaceous to Oligocene. Our hypothesis is that the restrainining bend formed first in the Svalbard during the latest Cretaceous - perhaps as a consequence of existing grains in the continental crust of the once fused area of Greenland and Svalbard. To maintain zero bulk volume change in a plane strain strike-slip system, the excess volume of deformed crust at the Svalbard restraining bend segment during latest Cretaceous to Eocene time must be balanced by a volume deficit in the adjacent, along-strike area of the Vestbakken releasing bend. Because mass balance of the crust is preserved when compression and extension are coeval, the area of thinned crust in the Vestbakken basin is equivalent to the thickening in the Svalbard restraining bend area and therefore the overall curved fault geometries seen in the geologic and magnetic maps remains similar. The vergence of the Svalbard thrust belt at a high angle to the strike-slip zone indicates that strain partitioning occurred and not all shortening is in the plane of the strike-slip fault. We propose to test the conceptual paired bend idea with quantitative plate reconstructions, regional mapping and basin modeling.