Kongsfjell-områdets geologi, en petrografisk og strukturell undersøkelse i Helgeland, Nord-Norge.
Abstract
The area investigated is situated in the Rødingsfjell nappe of the Norwegian Caledonides in Helgeland, North Norway. The study is divided into two main parts; the first structural and the second petrographic. The first section contains a description of different structural elements and the various mesoscopical and macroscopical structures encountered in each of the structural subareas. It is concluded that at least some parts of the area investigated have suffered three phases of folding. The first (F1) phase produced large-scale and small-scale similar-type folds following both WNW and SSW trending axes. Contemporaneously the western part of the area, the marble-rich Anders Larsa Group was thrust at a low angle to the east over the Kongsfjell Group constituting the complex, transversal Jørentind Synform. During the second phase of folding (F2) the Kongsfjell Group was \"wrapped\" around the Anders Larsa Group, the latter forming the core of a regional and almost isoclinal fold plunging to the SSW. The effects of the second phase are less evident towards the east. The small-scale second phase folds are more open, assymetric, flexural-slip folds. Both the Anders Larsa and the Kongsfjell Group are overthrust by a nappe in SSW (Tustervann region). During the third deformation the F1 and F2 structures were deformed in the western part of the area.