Magnetic fabrics and paleomagnetism of the Storsjön-Edsbyn deformation zone, central Sweden

Sammanfattning: Anisotropy of magnetic susceptibility (AMS) and paleomagnetic data from the Storsjön-Edsbyn Deformation Zone (SEDZ) in central Sweden are presented. The SEDZ is a regional shear zone c. 200km in length that cuts through 1.7-1.9 Ga old rocks in the central part of the Fennoscandian shield. The AMS analyses support a tectonic model suggesting that the SEDZ is a pureshear dominated transpression zone. The width of the zone in its southern part is defined to c. 10-12km and in the northern part it is c. 20-25km. A dolerite sill that truncates the plastic deformation pattern of the SEDZ postdates its activity to c. 1250 Ma, but paleomagnetic data from a dolerite dike indicates that the zone may be older than c. 1.6 Ga.