Open AccessPrecambrian structures of the Ikorfat peninsula, Agto region, West Greenland
Author(s) -
Lilian Skjernaa
Publication year - 1973
Publication title -
rapport
Language(s) - English
Resource type - Journals
eISSN - 2597-2944
pISSN - 0418-6559
DOI - 10.34194/rapggu.v52.7331
Subject(s) - geology , gneiss , metamorphism , geochemistry , hornblende , precambrian , biotite , sequence (biology) , granulite , basement , metamorphic rock , pegmatite , petrology , geomorphology , paleontology , archaeology , facies , history , quartz , structural basin , biology , genetics
A supracrustal sequence of biotite gneisses, light coloured garnet-biotite gneisses (metasediments) and metabasite rocks is bounded to the north-west and south-east by basement rocks of biotite (± hornblende) gneisses and metabasites. The supracrustal sequence lies in the core of a major F3 synform. Metabasite horizons are used as marker horizons to elucidate the structure of the area. Hornblende-granulite subfacies metamorphism accompanied the F3 folding; later retrograde metamorphism only affected the rocks along master joints and thrusts. Structural analysis of the basement rocks indicates at least two folding phases older than the F3 folding of the supracrustal sequence; the supracrustals also show minor folds of a fourth phase.