Abstract
Structural studies in the pre-Cambrian of western Greenland. Part II. Geology of Tovqussap nunâ
Highlights
Tovqussap nuna is situated in the southern part of the Sukkertoppen district, West Greenland
According to SØRENSEN the ultrabasic rocks form lenticles comformably enclosed by gneiss, which latter is regarded as having been formed at the expense of amphibolite
Dioritic and meta-dioritic aplites have been observed at various localities in Tovqussap nuna
Summary
The essential base for the structural analysis is a geological map. The more accurate and detailed the mapping the more accurate are the results of the analysis. The author uses the following definition for gneiss: a metamorphosed, medium to coarse grained rock in which (or part of which) quartz-feldspar predominates and which on a mesoscopic scale shows banded, veined, streaky, smallfolded or any similar structures (due to compositional and textural variations) and/or parallel arrangement of the dark minerals in some or all of the rocks. When the term charnockite has not been applied in the description of the Tovqussaq rocks it is primarily because charnockite sensu stricto has not been found within the region It may formerly have existed, in which case it has been completely altered to biotite gneisses during a subsequent phase of metamorphism under amphibolite facies conditions. Medium grained rocks have a grain size between 1 mm and 1 cm while coarse grained rocks have grains larger than 1 cm (in diameter)
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