Further work on the early Archaean rocks of the Isukasia area, southern West Greenland

Abstract

Work in 1981 on the early Archaean rocks of the Isukasia area (Ailaart, 1976) was an integral part of GGU's mapping programme of northern Godthåbsfjord, Fiskefjord and adjacent areas to the north-east. Within the Isukasia area, there was dose co-operation with Minik Rosing who was making detailed studies of certain aspects of the Isua supracrustal belt. The object of this summer's field work was to complete the study of the supracrustal belt and the central gneisses that was started last year (Nutman et al., in press), and to see as much as possibIe of the gneisses between the supracrustal belt and 65°N (fig. 18). For the mapping of the supracrustal belt, manuscript maps drawn by J. H. Allaart were an invaluable starting point. Besides regional mapping, detailed studies were made of the nature of the lithological units and the relationships between them; see Table 4 for chronology. Suites of rocks were collected for isotopic and geochemical studies. In connection with this, H. Baadsgaard spent 10 days working with the author in the area, as a guest of GGu. The results reported here supplement those given by Nutman et al. (in press).