The continental margins of the Norwegian-Greenland Sea: recent results and outstanding problems

Abstract

Within a framework of plate tectonics the passive continental margins of the Norwegian-Greenland Sea may be classified as composed of rifted and sheared segments. An exception is the margin north of the Greenland-Senja Fracture Zone which appears to be of a combined sheared-rifted type. The margins south of the Greenland-Senja Fracture Zone are in part underlain by basement highs on the lower continental slope. Associated features are: marginal escarpments, depth anomalies, smooth opaque acoustic basement and changes in the geophysical parameters across the landward termination of the marginal basement highs. Drilling results have revealed basalts at the level of the acoustic basement. These observations have been related to Early Cainozoic rifting and the transition between continental and oceanic crust. Recent studies have mainly focused on the eastern margin. Off Spitsbergen there is a typical north-trending structural fabric, including a prominent fault of the central shelf. Structurally, the margin between Jan Mayen and Greenland-Senja fracture zones appears to be composed of two parts. The southern part is characterized by a northward plunging basement high (Voring Plateau) underlain by an inner zone of sub-basement reflectors, whereas prominent block faulting is typical for the northern part. North of the Voring Plateau the acoustic basement appears to extend almost to the shelf edge and is probably a flow basalt. We believe that these observations are related to the rifting and the earliest phase of seafloor spreading in the Norwegian-Greenland Sea.