Cretaceous-Paleocene Evolution and Crustal Structure of the Northern VOring Margin (Offshore Mid-Norway): Results from Integrated Geological and Geophysical Study

We present results of a multidisciplinary study of the northern segment of the VOring volcanic rifted margin, offshore mid-Norway. This segment represents a transitional margin domain that is less investigated compared to the adjacent segments of the margin. In order to understand the geological evolution of the study area, we performed an integrated interpretation of an extensive geological and geophysical data set. This data set includes recently acquired and reprocessed 2-D reflection seismic, published refraction data and potential field data, as well as new borehole data. Two-dimensional potential field modeling was performed to better assess the crustal architecture and evolution of the northern VOring Margin. We then consider how crustal-scale structures and processes affected the basin formation. The outer and distal northern VOring Margin represents a series of deep Cretaceous (Traena Basin and Nagrind Syncline) and Cretaceous-Paleocene (Hel Graben) sag subbasins underlain by a significantly thinned continental crust. These subbasins developed in between structural highs (Utgard, Nyk, and Grimm Highs), which are underlain by a thicker crust and interpreted as a series of rigid continental blocks (buffers). In addition to the regional Late Jurassic-Early Cretaceous rifting events, we found structural evidence of local Neocomian and mid-Cretaceous extensional reactivation affecting the northern segment of the VOring Basin. During the mid-Late Cretaceous-Paleocene, the extensional axis within the VOring Basin province migrated sequentially northwestward to the present-day continent-ocean boundary. We also show fundamental differences between the volcanic rifted mid-Norwegian Margin and nonvolcanic (Iberian-type) margins and how preexisting structures events can shape the evolution and architecture of the margin.