The Amîtsoq gneisses are among the older metamorphic rock complexes yet discovered on Earth. These rocks outcrop on the southwestern coast of Greenland, where they extend over more than 50 km northeast of Nûk (Godthåb). The oldest age obtained on a zircon crystal extracted from a tonalitic gneiss sample is of 3.872 ± 0.010 Ga.
The Amîtsoq gneisses outcrop on the southwestern coast of Greenland, where they extend over more than 50 km northeast of Nûk (Godthåb), along the southern coast of the Godthåbsfjord. After long and detailed field work, Mc Gregor (1968, 1973) was the first who recognized these Archaean terrains as among the oldest in the world. He distinguished two groups of gneisses: (1) very old ones cut by mafic dykes (Ameralik dykes) that he called the Amîtsoq gneisses, (2) younger ones emplaced after the Ameralik dykes and that are known as the Nûk gneisses. Both groups are crosscut by the late Qôrqut granite. The first...
KeywordsGreenland Isua Supracrustal Belt Archaean TTG Gneiss Metamorphic rocks
References and Further Reading
- Bridgwater D, Schiøtte L (1991) The Archaean gneiss complex of northern Labrador. A review of current results, ideas and problems. Bull Geol Soc Den 39:153–166Google Scholar
- McGregor VR (1968) Field evidence of very old Precambrian rocks in Godthaab area, West Greenland. Rapp Gronlands Geol Unders 19:31Google Scholar