Zur Geologie und Tektonik des Akersvatn Gebietes, Rana, Nordland.

Abstract

The Akersvatn region is located within the high-metamorphic R\u00CEdingsfj\u00CCll Nappe in the Central Scandinavian Caledonides. The investigated area is subdivided into three tectonic units: The Græsfjell Complex, the Umbugten Unit and the Akersvatn Unit. The Akersvatn Unit, which is separated from the Umbugten Unit by a fault, is distinguished by rapid lateral facies changes. Furthermore, the style of deformation is complex compared with that in the Umbugten Unit. The succession, which is similar in both units, consists of meta-arkoses, pelites, psammites, marbles and subordinate meta-tuffs. The basal part of Akersvatn Unit is presented by an additional formation, the Mofjell Gneiss. The Græsfjell Complex, tectonically superimposed on the Akersvatn Unit by thrusting, consists of a monotonous series of garnet-mica schists which cannot be correlated with any other rock-types in the area. Typical mineral assemblages indicate that metamorphism took place under almandine-amphibolite facies conditions. Variations of metamorphic grade have not been observed.