The geology of the Vaddas area, Troms: a key to our understanding of the Upper Allochthon in the Caldonides of northern Norway

Abstract

The Vaddas area in the North Norwegian Caledonides is underlain by the Corrovarri Nappe, the uppermost unit of the Kalak Nappe Complex, and the overlying Vaddas Nappe representing the lowermost unit of the Reisa Nappe Complex. Both nappes form part of the Upper Allochthon. Only the upper part of the Corrovarri Nappe, the Nahpojohka Group, which at c.580 Ma was intruded by a rift-type, intracratonic to marginal basin, dolerite dyke swarm and related gabbro source rocks, has been studied in detail. It is proposed that the rocks of the Corrovarri Nappe were deformed during a poorly understood Finnmarkian tectonometamorphic phase, involving subduction and exhumation at around 500 Ma, and were part of the margin of the Baltican continent. The Corrovarri Nappe served as basement for the overlying stratigraphic sequence of the Vaddas Nappe, although the contact now represents a major tectonic break.\r(Forkortet)