Abstract
Kangikajik peninsula in the northern part of the Ammassalik region is composed of a high grade complex of Precambrian gneisses and supracrustal rocks. Amphibolites occur both in the gneisses and supracrustal rocks which are folded together and generally interleaved. At Grusgraven, a corrie on the south coast, a particularly well-exposed outcrop reveals border relationships between gneiss and supracrustal rocks. These relationships, as well as the internal characters of the rocks, favour a model where the regional gneisses present a basement to a cover sequence composed of metasediments and amphibolites. Whether this involves an Archaean – early Proterozoic association, as isotopically dated elsewhere in the region, is unknown.
Highlights
Kangikajik peninsula in the northern part of the Ammassalik region is composed of a high grade complex of Precambrian gneisses and supracrustal rocks
At Grusgraven, a corrie on the south coast, a particular1y well-exposed outcrop reveals border relationships between gneiss and supracrustal rocks. These relationships, as well as the internal characters of the rocks, favour a model where the regional gneisses present a basement to a cover sequence composed of metasediments and amphibolites
Introduetion ane of the most fundamental and persistent problems in the study of the crystalline complexes of Greenland has centred on the age relationships of supracrustal belts to gneissic rocks
Summary
Wager (1934) recognized in the coastal area of the Ammassalik region widespread belts of 'altered sediments' associated with amphibolites and ultrabasic rocks. These, he noted, were intimately associated with, and injected by, the regional grey orthogneisses suggesting that the supracrustal rocks were the older. FolIowing regional mapping, Bridgwater & Gormsen (1968, 1969) and Wright et al (1973) adhered to the opposing view that the gneisses represent a basement to the metasediments and associated rocks. It is pertinent to note that Wager (1934) stressed that the field relationships on which his chronology was based were open to question He pointed out that the regional gneisses may comprise more than one age of material and that reworking of gneisses has taken place. The corrie faces Bjørnebugt and is locatce! al approximarely 66" OYN, 15" 50'W (rigs 1&2)
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