Geology of the Røssjøkollan-Dokkvatn area, Oppland.

Abstract

The Røssjøkollan-Dokkvatn area at the eastern edge of Valdres Sparagmite exposures is comprised of a number of allochthonous litho-tectonic units in which Precambrian Jotun basement, and Late Precambrian or Eocambrian Valdres Group, tillite, and equivalents of the Vangsås Formation occur in conformable sequence beneath Cambro-Ordovician slates and arenites. The late Precambrian age of the Valdres Group has been corroborated on the basis of sedimentary relationships to the known Eocambrian Vangsås Formation. The various allochthonous litho-tectonic units exhibit differences in sequence and facies which suggest that they are derived from slightly different sedimentary areas within the same root zone. Of the four phases of deformation recognized, the first two were most important in affecting the configuration of large units of rock. Litho-tectonic units of the Valdres nappes emplaced during D1 were penetratively deformed and elongated in the NW-SE direction during D2. The slaty cleavage, elongation lineations and regional low grade metamorphism are all products of D2. Later deformation is recorded in several slip cleavages and in steeply-dipping, Post-Caledonide, faults.