K/Ar age determinations from western Greenland II. The Ivigtut region

Abstract

The Ivigtut region is particularly remarkable for providing one of the best known examples of the transition between two Precambrian fold belts (Henriksen, in press; Allaart, Bridgwater and Henriksen, in press). In the north-east part of the area sediments and volcanics of the Ketilidian fold belt lie with a pronounced unconformity on gneisses and schists of the pre-Ketilidian basement. Traced southwards the Ketilidian supracrustal rocks show an increasing grade of metamorphism and the unconformity with the underlying basement is gradually obliterated as the basement becomes increasingly reactivated.