Basic rocks of the Gardar igneous province

Abstract

The mapping of south-west Greenland by the GGU to a scale of 1:20 000 has revealed a profusion of unmetamorphosed dolerite dykes within the Precambrian basement. Although obviously younger than the latest regional metamorphic event, these basic rocks are either older than, or approximately contemporaneous with, such central igneous complexes as Ilimaussaq and Kungnåt, and it is now clear that basic magmatism played a major role in the evolution of the Gardar alkaline province of which these complexes form a part. This is further attested by the preservation of basaltic lavas within the region, particularly within the down-faulted block of the Ilimaussaq peninsula. The basic intrusions and lavas are believed to be between 1400 and 1000 m. y. old.