Frode Ofstad

A recent aeromagnetic survey was carried out to refine our understanding of the structure and nature of the basement rocks beneath the Finnmark Platform (Norwegian Barents Sea). Magnetic depth source estimation and potential field models were used to explore the platform's basement architecture and evaluate the existence of Paleozoic basins. In the western part, magnetic fabrics suggest a continuation of Precambrian rocks into the adjacent platform. Further east, magnetic data reveal NW–SE-trending basement lineaments related to the Sørøya–Ingøya Shear Zone, formed during the Caledonian orogeny. Additionally, lower-frequency and discrete NNW–SSE lineaments may reflect the influence of older Precambrian structures. The Gjesvær Low, previously considered a post-orogenic basin, is now seen as a Caledonian backthrust system tied to the Sørøya–Ingøya Shear Zone. Both Precambrian and Caledonian inherited structures controlled and accommodated the development and segmentation of subsequent rift basins during the Paleozoic and Mesozoic. The NW–SE to WNW–ESE Precambrian trends guided early rift segmentation from the Devonian to Early Carboniferous, while Mesozoic rift border faults align with NE–SW to ENE–WSW-trending magnetic lineaments, largely interpreted as Caledonian in origin.