Geology and geochronology of the Hardangerjøkulen Klippe and its basement

The main goal of this thesis is to make a tectonostratigraphic map of the North to North-east part of Hardangerjøkulen (Klippe), close to Finse. The area is defined by three main units: the Basement, Phyllite and the Middle Allochthon. The basement is characterized by granitic and gabbroic lithology, both with an age of 980 Ma. Pegmatitic dikes that intrudes the basement (both granite and gabbro) represents an event occurring at 940 Ma. Phyllite, the lithology above has weakly responded during thrusting/folding of the overlaying informal unit, Lower nappe, as Phyllite is often in-folded in Lower nappe fold structures. Lower nappe is comprised of several different rock types with more or less different lithologies, such as fine-grained banded gneiss, schist, carbonate, volcanic tuff and also lithologies very similar to Phyllite. The Lower nappe is highly folded with mylonitic fabric. The highest unit is the “Upper nappe”, another informal name, and this is the crystalline basement part of upper Middle Allochthon. The Upper nappe is also highly folded with mylonitic fabric, but with coarser grain sizes relative to the Lower nappe, it is characterized as banded gneiss. The dominated fold-axes orientations are trending NW-SE with vergence towards NE, while the second most dominant direction is trending NE-SW with vergence towards NW. These two fold-axes orientations are located at geographically different places, but still appearing in the same lithologies. Between the lithologies which has folds with fold-axes trending either NW-SE or NE-SW, a transitional zone is recognized as the fold axes are rotating/changing over a small area (approx. 100 meter). Apparently the study area represents four deformation sequences: Sveconorwegian orogeny (~1000 Ma), Dalane Phase (940 Ma), Caledonian orogeny (420 Ma), Devonian extensional phase (~410 Ma). The orientations of the fold axes (NW-SE or NE-SW) determine which phase the lithology was deformed by.