A geophysical study of the continental margin west of Norway

Abstract

A geophysical investigation of the continental margin between Norway and the Faeroe Islands has been carried out, utilizing gravity, magnetic, bathymetric, seismic refraction and seismic reflection data. Detailed analysis of this data has shown that the boundary between the oceanic-type crust beneath the Norwegian Basin and the continental-type crust of North-West Europe does not lie along the Faeroe-Shetland Escarpment as suggested by Talwani and co-authors. The line of splitting between the More region and Greenland has been identified as lying just to the south-east of magnetic anomaly 24 within the eastern Norwegian Basin. This is supported by seismic reflection and gravity evidence. Gravity data over the margin has been interpreted as revealing a zone of anomalously thin crust which may mark a north-eastern extension of the Faeroe-Shetland Channel. It is separated from the Norwegian Basin by a zone of rather thick crust forming a spur from the Faeroes Block. It is proposed that the zone of anomalously thin crust be known as the East Faeroes Trough. Within the Norwegian Basin the magnetic data confirms that the sea-floor spreading anomalies form a fan-shaped pattern narrower in the south than in the north. Seismic reflection data within the central portion of the basin shows rough and undulating basement topography, with many basement peaks, some of which form the seamounts detected on earlier bathymetric surveys. It has been tentatively suggested that the basement peaks and lack of correlatable magnetic anomalies in the centre of the basin are due to the continual westward migration of the spreading axis.