Basement Inheritance and Its Influence on Rift Evolution and Rifted Margin Architecture: The North Sea and Mid-Norwegian Margin.

The Mid-Norwegian margin and the North Sea rift are among the most extensively studied regions in the world, owing to their abundant geological and geophysical datasets. Their basement architecture is complex, having been shaped by the Silurian Caledonian orogeny and subsequent gravitational collapse during the Devonian. This was followed by multiple rifting episodes, separated by periods of tectonic quiescence. While the North Sea subsequently entered a post-rift phase dominated by thermal subsidence, rifting along the Mid-Norwegian margin persisted until continental breakup in the early Eocene.

Despite these studies, the mechanisms by which remnants of the Caledonian orogeny influenced later rifting stages remain unclear. For many years, seismic imaging could not penetrate to the depths required to investigate the complete basement architecture. Recent advances in seismic reflection imaging, however, have enabled the acquisition of long-offset, deep, high-resolution profiles extending up to 16 seconds two-way travel time (s-TWTT). The GeoexMCG Regional Deep Imaging (RDI) dataset thus provides an unprecedented opportunity to study the entire basement architecture, including the lower crust and lithospheric mantle.

This contribution summarizes the first results of a PhD study focused on a large-scale interpretation of the RDI dataset, supported by offshore-onshore geological correlations and gravity and magnetic modelling. Units with distinct seismic facies -i.e., zones of consistent reflectivity characterized by amplitude, frequency, and continuity - were defined in Petrel after multiple mapping iterations. Based on these results, the aim of the PhD study is to explore how inherited basement structures influence continental rifting and the formation of rifted margins at large scales.