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Abstract

We study the structural evolution offshore Norway and the resulting consequences on the potential of hydrocarbons. Therefore structural restoration in 2D and 3D structural modelling is used to quantify subsidence and uplift as well as shortening and extension. Based on interpreted seismic data, first results have been obtained from structural restoration of transects running NW-SE from the Trondelag Platform in the E across the Nordland Ridge, the deep Vøring Basin, the Fles Fault Complex, the Gjallar Ridge to the Marginal High in the W. They suggest that the impact of Quaternary glacio-isostatic vertical movements on the rifted margin is minor and has affected only the eastern part of the Trondelag Platform. The Cenozoic was predominantly a period of passive infilling and possibly declining thermal subsidence. The transition from Late Cretaceous to Paleocene was characterized by uplift and extension at the westernmost edge of the continental margin (Gjallar Ridge), following a late Cretaceous phase of shortening. In contrast, continuous thermal subsidence is the dominating phenomenon in the deeper parts of the Vøring Basin during large parts of the Cretaceous. The 3D structural model integrates data of 5 sedimentary layers (courtesy of Norwegian Petroleum Directorat) and the thickness of the crystalline crust from OBS-data. It images shifting depocentres and shows relationships between subsidence controlling features and the properties of the deeper crust. The results indicate that the structural history has to be implemented in the evaluation of petroleum systems as the lateral heterogeneity of deformation is considerable along the Norwegian margin.