The Caledonian mountain chain of the Southern Troms and Ofoten areas. Part I. Basement rocks and Caledonain meta-sediments.

Abstract

The geology of the present area will be treated in a series ofthree publications. In the first paper the petrography and generalfeatures of the Precambrian rocks and the so-called \"basal gneisses\"are described and the interrelations of these rocks are discussed. Inaddition, description and comments on the stratigraphy, petrography andmetamorphism of the Caledonian meta-sediments are presented. It isshown that chemical, mineralogical and general structural relationspoint to a close relationship between the Precambrian Rombak window andthe basal massif of Tysfjord. Thrust sheets of Precambrian granite inthe Caledonian schist within the Rombak profile and the Hinnøy area aredescribed. These observations support the hypothesis of Kautsky thatgneiss-granite layers in schists of the Tysfjord area as well as theborder gneiss of the Tysfjord granite are thrust sheets of CaledonizedPrecambrian rocks. The presence of thrust planes at several levelswithin the Caledonian metasediments renders the original stratigraphyuncertain. The sequence is divided into the following groups, inascending order: Hyolithes Zone, Storfjell Group, Rombak Group, NarvikGroup, Salangen Group Niingen Group (Table III).