Om Grongkulminasjonen og Grongfeltets skyvedekker.

Abstract

On the Grong culmination and the thrust nappes of the Grong area: This paper presents of the major tectonic features of a central part of the Caledonides of Norway, based upon the very detailed and exact geological manuscript maps worked out by Steinar Foaslie in the period 1922-1943. The following features are distinguished: 1) The Olden nappe, situated centally in the Grong culmination, 2) the overlying Seve nappe. In the Grong area (northern half of pl. 1) the Seve nappe is divided into 3) the western nappe of highly metamorphic rocks and 4) eastern nappes of low metamorphic rocks (greenschist facies). 1) The Olden nappe consists of pre-Cambrian rocks, mostly coarse granite, overlain by small remnants of a Cambro.Ordovician series. Above this is thrust the pre-Cambrian rocks of the Seve nappe. 2) The Seve nappe consists of coarse-grained and fine-grained granitic rocks overlain by a Cambro-Siluruan series of sediments and effusives both in the northeast and the southwest. The southwestern series are folded into two marked synclines which terminate against the pre-Cambrian rocks which make up a highland, therefore this anticlinal structure is called the Grong culmination. 3) The western nappe of the Grong area continues from the north where it was discovered by Strand (1953).