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Bathymetry and single seismic reflection methods were used to study the seafloor inhomogeneities in the Norwegian-Greenland region. North of the Mohns Ridge we have identified nearly east-west trending morphostructures (MS) in seafloor relief, which are horst ridges separated by troughs, and have provided their characteristics. We carried out a seismostratigraphic analysis to study the structure of the Cenozoic sedimentary cover and the conditions that existed during its formation. We showed that these seafloor MSs came into being after the origination of the Cenozoic sedimentary cover (during post-Quaternary time); that is to say, they are young features, and are not reflected in the magnetic anomalies of the Greenland Basin. We examined bathymetric characteristics and earthquake focal mechanisms within the Mohns Ridge to provide a preliminary identification of transverse faults (probably of the normal-oblique type) that control the blocky structure of the ridge.

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An analysis of the deep structure of the East Greenland margin (Blosseville Kyst to Liverpool Land) and of the Jan Mayen microcontinent resulted in the development of a crustal model that was valid for both before their disruption. A joint model clearly demonstrates the net result of rifting phases during Paleozoic, Mesozoic, and Cenozoic time. Starting from the Devonian, a graben-shaped depression about 180 km wide existed between Liverpool Land and the Jan Mayen Ridge; the depression was formed by subsiding of the crystalline basement that was not compensated by sedimentation. The marine basin was approximately 2 km deep during late Devonian time. The west-east joint deep crustal section clearly defines three depths in the upper mantle that fit dome-like surfaces superposed on each other. We interpret these surfaces as temperature fronts of mantle plumes that differ by their time of origin: Paleozoic, Mesozoic to Cenozoic, and late Cenozoic. The rim of the present-day Blosseville Kyst and Liverpool Land shelf is found to be underlain by a basement high that is associated with the axis of a positive free-air gravity anomaly. East of the high along the anomaly axis, we identified a continent-ocean boundary. The present-day phase in the geological evolution of the Greenland-Norwegian region north of Iceland is characterized by an increased thermal state of the lithosphere and manifestations of intraplate tectonics.