Abstract

The southern part of the continental margin off southern West Greenland is an amagmatic margin that may have taken at least 30 and possibly more than 60 million years to form during the Cretaceous at an average extension rate of between 8.7 and 4.4 mm a ^-1. To its northwest and east are volcanic continental margins formed in the Early Tertiary when sea-floor spreading started above the hot North Atlantic plume head. The survival of the amagmatic margin means that plume head material could never have been present under it and therefore the plume head could not have had the circularly symmetric shape commonly depicted in the literature.