Geology and structure of the Beito Window, Valdres.

Abstract

Three groups of Caledonian nappes sit directly on Precambrian gneisses. The lowest nappe consists of generally upward-facing parautochthonous or allochthonous Cambro-Ordovician quartizites and phyllites. The middle nappe is a complex of repeated slices of inverted Eocambrian sparagmites with associated Jotun igneous rocks. The highest nappe is the Jotun nappe. The Precambrian basement beneath the nappes is part of a pre-thrusting ridge which has influenced the emplacement of the Caledonian nappes. The nappe emplacement was the first Caledonian structural event in the area but the formation of the main slaty cleavage and stretching lineation would appear to have outlasted thrusting. Some thrust rejuvenation took place during a later tectonic phase and the effects of six Caledonian tectonic phases are evident in the area.