Caledonian basement of the western Barents Sea

Abstract

Major crustal units in the western Barents Sea have been defined on the basis of depth‐converted seismic reflection data, gravity and magnetic anomaly data. The seismic data revealed three types of crustal reflectivity below the sedimentary rock units, i.e., transparency, strong lower crustal reflectivity, and thoroughly reflective. The crustal structures obtained from the seismic reflection data are supported by 2D density and magnetic modeling. Three NE‐SW‐striking crustal units have been observed south of Bjørnøya. Changes in reflectivity in southwestern Barents Sea are accompanied by gravity and/or magnetic anomalies. North of Bjørnøya, two basement provinces could be distinguished. The observed outlines of the crustal blocks in the southwestern Barents Sea match with Caledonian main thrusts onshore northern Norway. We were therefore able to outline the continuation of Scandian nappe complexes in the southwestern Barents Sea. The crustal unit to the west of the Loppa High region is supposed to be a fragment of Laurentia, since the Loppa High region aligns with the Uppermost Allochthon nappes onshore, and is therefore expected to be the collision zone between Baltica and Laurentia. The southeastern crustal unit aligns with the Lower to Upper Allochthons and their Fennoscandian basement onshore. A compilation of all known thrusts and sutures in the western Barents Sea revealed the complexity of the Iapetus closure. It challenges the concept of two Caledonian main branches (NE and N). The thrusts/sutures are fan‐shaped distributed across the western Barents Sea, resembling the structure of the Late Paleozoic–Mesozoic/Paleocene rift basins and basement highs in the southwestern Barents Sea.