Overview Over Formation Mechanisms, Structural Domains and Petroleum Systems Implications for Palaeozoic Depocenters of the Norwegian North Sea

Abstract

Upper Palaeozoic basins in the Norwegian North Sea remain among the least understood exploration targets on northwestern Europe's cratonic margins, underscoring the need to refine exploration models. Knowledge of Devonian–Permian stratigraphy and structure in this sector is constrained by sparse well data, poor seismic resolution, deep burial and limited exploration success, despite well-established southern North Sea petroleum systems. This study addresses these gaps by investigating Palaeozoic basin formation mechanisms and their petroleum system implications. By integrating well and seismic data, we have identified four Devonian–Permian tectonosequences and defined three structural domains based on fault architecture. In the Northern Domain, a southwest–northeast-striking Devonian depocenter is interpreted as a pull-apart basin featuring folded Devonian deposits separated by an intra-Devonian unconformity. These characteristics indicate transtensional basin development followed by dextral transpression linked to the Highland Boundary and Southern Uplands faults. The Central and Southern domains formed a Carboniferous backbulge basin north of the Variscan Orogen, where the Mid North Sea–Ringkøbing–Fyn High may have acted as a forebulge. Late Carboniferous–Permian volcanism likely added flexural loading, followed by tectonic quiescence and thermal subsidence recorded in the Rotliegend Group. We infer two distinct petroleum system types: The Northern Domain may host potential Devonian lacustrine source rocks with Devonian–Permian reservoirs, whereas the Central and Southern domains may host Carboniferous coaly source rocks with Carboniferous–Permian reservoirs that resemble Variscan-related systems of the southern North Sea and northwestern Europe. The link of these Palaeozoic domains with orogenic phases and plate-tectonic evolution stresses the need to understand the overall tectonic framework when interpreting basin evolution near ancient plate boundaries. This perspective can help guide exploration efforts where presalt successions remain poorly imaged or largely unexplored.