Multiple folding in the Sørfinnset area of Northern Norway.

Abstract

120 km\u00B2 of the Norwegian Caledonides have been mapped on aerial photographs on a scale of approximately 1:15 000. Detailed correlation between the folded schist successions has enabled the effects of the earliest movements to be distinguished and assessed more completely than in adjoining areas. This F1 deformation comprised large-scale, premetamorphic nappe development, probably on E-W axes, accompanied by extensive sliding and may be compared with that postulated by Rutland and Nicholson (1965) as forming the basis of the Beiarn nappe which impignes on the eastern margin of the Sørfinnset area. Most of the more obvious structural components of the Glomfjord nappe complex developed during the succeeding F2 and F3 deformations which were accompanied by metamorphism. F2 comprised two or perhaps more overlapping phases, the earlier of which was particulary intensive giving isoclinal folds again with more or less E-W axes. Basement gneisses were involved in these folds and provide the core to the F2 nappes which have envelopes of sparagmite and a wide variety of schists of the Meløy Group. Late-F3 open folds with steep axial planes and a gentle plunge to the SSW have given the earlier folds an easterly to southeasterly plunge.