Dislocation sets in northern Sweden

Abstract

The interpretation of low-altitude, aeromagnetic measurements from six areas (each 50 × 50 km) in the Precambrian of northern Sweden yields distinct sets of dislocations with main directions of −35°, 0° and 55°. These dislocations appear to be of transcurrent-fault type. The displacement for the −35° direction is mainly sinistral and vertical, and for the 55° direction exclusively dextral. The 0° direction shows displacement patterns that may be interpreted as exclusively vertical. The apparent, mean, lateral displacement is 400 m, with slight changes in different directions. The dislocations occur at preferred distances with a maximum at about 30 km. On a regional scale, the two main dislocation sets are parallel to the present, active, fracture zones, as indicated by recent seismic activity and mapped, post-glacial fault movements. It is concluded that the low-altitude aeromagnetic anomalies give very clear indications on a regional scale of dislocations and their displacement.