Open AccessField evidence of very old Precambrian rocks in the Godthåb area, West Greenland
Author(s) -
V. R. McGregor
Publication year - 1968
Publication title -
rapport
Language(s) - English
Resource type - Journals
eISSN - 2597-2944
pISSN - 0418-6559
DOI - 10.34194/rapggu.v15.7172
Subject(s) - gneiss , geology , precambrian , metamorphism , granulite , geochemistry , facies , radiometric dating , metamorphic facies , biotite , metamorphic rock , geomorphology , paleontology , quartz , structural basin
The Godthåb area, situated in the old central gneiss complex of West Greenland, has yielded two of the oldest radiometric dates yet obtained from Greenland. They are both K/Ar biotite dates, one of 2710 ± 130 m.y. on granodiorite gneiss from Godthåb (Armstrong, 1963), and the other of 2610± 50 m.y. on gneiss collected 55 km to the north and on the opposite side of Godthåbsfjord (Larsen and Møller, this report). The latter gneiss shows evidence of having undergone retrograde metamorphism from granulite facies to amphibolite facies, and its date is presumed to be related to this retrogression (Windley, in press).