Aeromagnetic basement complex mapping north of latitude 62°N, Norway.

Abstract

The Geological Survey of Norway (NGU) has conducted aeromagnetic measurements over Norway since 1959, and to date approximately 90 % of the country has been covered with 435,000 line kilometres of such measurements. Since 1962 NGU has also measured 183,000 kilometres of aeromagnetic profiles over Norwegian shelf areas. An interpretation in terms of depth to magnetic basement reveals that the shelf north of 62 N is composed of great thicknesses of sediments. Even in Vestfjorden, a major fjord south of Lofoten, there are more than 4 km of sedimentary rocks. In the Barents Sea some special problems arise in the interpretation due to the presence of several kilometres of non-magnetic, Late-Precambrian-Eocambrian sediments. An aeromagnetic survey over the Varanger Peninula shows up to 7 km of such sediments. The Caledonian belt of metamorphic rocks is practically non-magnetic, except for some small iron ore-bearing formations and scattered ultrabasic bodies. However, in addition to anomalies from the basement, which is probably the Precambrian Baltic Shield, it has been possible to trace anomalies from a shallow level (?Paleozoic).