Early Cenozoic crust at the Norwegian continental margin and the conjugate Jan Mayen Ridge

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Abstract
Multichannel seismic profiles at the Vøring Plateau Margin off Norway and the northern Jan Mayen Ridge have provided a framework for the early Tertiary evolutionary history of these areas which were adjacent prior to the opening of the Norwegian Sea. We propose that their Paleogene evolution is quite similar and that the two acoustic basement reflectors, EE and JO, were formed in the early Eocene by extrusion of flow basalts. From the time of opening to about anomaly 23 time, oceanic seafloor was generated by Icelandic‐type spreading. During that time, the Central Jan Mayen Fracture was the main transform. The seaward dipping reflector sequences are flow basalts generated by the Icelandic spreading. The existence of less well developed dipping sequences seaward of the primary ones probably reflects that these regions submerged later because of higher initial elevation. During the early Eocene subaerial spreading episode, which is related to the North Atlantic Volcanic Province, basalt flows also covered the adjacent thinned and heavily intruded continental crust. It is proposed that the continent‐ocean boundary is located just landward of anomaly 24B, a short distance seaward of the Vøring Plateau Escarpment. Reflector K is only recognized landward of this boundary in a region of “transitional crust.” The escarpment experienced syndepositional faulting, and the most elevated parts of the Vøring Marginal High did not subside below shallow water depths before Oligocene/Miocene time. We suggest that the Vøring Margin and the Jan Mayen Ridge represent “volcanic” passive margins. The evolution of this margin type may relate to initial uplift due to rifting in previously thinned crust.