Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso

Amitsoq Gneisses

  • Hervé Martin
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_5130-5

Synonyms

Definition

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.

Overview

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...

Keywords

Greenland Isua Supracrustal Belt Archaean TTG Gneiss Metamorphic rocks 
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References and Further Reading

  1. Black LP, Gale NH, Moorbath S, Pankhurst RJ, McGregor VR (1971) Isotopic dating of very early Precambrian amphibolite facies gneisses from the Godthaab district, West Greenland. Earth Planet Sci Lett 12:245–259CrossRefADSGoogle Scholar
  2. Bridgwater D, Collerson KD (1976) The major petrological and geochemical characters of the 3600 m.y. Uivak gneisses from Labrador. Contrib Mineral Petrol 54:43–60CrossRefADSGoogle Scholar
  3. 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
  4. Friend CRL, Nutman AP (2005) Complex 3670–3500 Ma orogenic episodes superimposed on juvenile crust accreted between 3850–3690 Ma, Itsaq Gneiss Complex, southern West Greenland. J Geol 113:375–398CrossRefADSGoogle Scholar
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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Laboratoire Magmas et VolcansUniversité Blaise Pascal, OPGC, CNRS, IRDClermont-FerrandFrance