An improved tectonic model for the Eocene opening of the Norwegian–Greenland Sea: Use of modern magnetic data

Abstract

Compilation of new and vintage aeromagnetric data from the Norwegian and Greenland Seas of the NE Atlantic provides evidence for a different interpretation of several tectonic elements. The previously interpreted oceanic fracture zones (Gleipne, Surt, Bivrost, Jenegga and Vesterålen) do not exist; these were artefacts of poor navigation and wide line spacing of the vintage dataset. This reinterpretation impacts our understanding of the early spreading history of the North Atlantic, as the opening of the Norwegian–Greenland Sea between the Jan Mayen and Senja-Greenland fracture zones occurred along a stable axis without offsets of the oceanic spreading anomalies or jumps in spreading axis. These results contradict the hypothesis that a spatial relationship exists between transfer zones and fracture zones on the Lofoten margin, and on the NE Greenland margin to which they have been projected. Simplified palaeogeographic reconstruction of the aeromagnetic map to Anomaly 22 reveals that a c. 50 km wide magnetic anomaly cuts across spreading anomalies 24A, 24B and 23 from the Vøring Marginal High on the Norwegian margin to Traill Ø on the East Greenland coast. The anomaly is interpreted to represent an igneous complex referred to as the Traill-Vøring igneous complex (TVIC). The complex crosscuts anomaly 22 on the Greenland margin, suggesting that the igneous activity was active until c. 50 Ma and can be linked up with the NNE-trending initial magmatic lineament (IML) extending between Traill Ø and Kangerlussuaq. The IML has been suggested to relate to a failed attempt of direct linkage between the Reykjanes and Mohns Ridges. The magnetic response of the TVIC along the Vøring margin has previously been interpreted as representing anomaly 24A and 24B. Such an interpretation required the erroneous introduction of an abandoned spreading ridge.