Kort beskrivelse av bergartene.

Abstract

Petrographic inspection of the rocks reveals that all of them, both sedimentary and igneous, are metamorphic. The igneous rocks are gabbroic and trondhjemitic. The rocks of gabbroic origin (among them probably hypabyssal basic igneous rocks) mostly belong to the amphibolite and the chlorite-amphibolite facies. The plagioclase, accordingly, is soda-rich, the amphibolite is pale coloured, probably actinolithic. There are also serpentine rocks and chlorite schist. - The metamorphism of the trondhjemites is cataclastic with sericitizing of the olagioclase and chloritizing of the femic constituents. It may therefore, be difficult, or impossible to distinguish between trondhjemites and trondhjemitic arkoses. In some cases, however, the igneous origin is proved, i.e. when the rock occurs as dykes. On the other hand also true arkoses occur. The sedimentary rocks are conglomerates, conglomeratic sandstones, argillaceous sandstones, and sandy shales. Well graded shales, consisting exlusively of clayey material are not observed, and also limestones are lacking. A small calcite content sometimes observed in the sediments may be of secondary origin (alteration of basic plagioclase). - Some of the conglomerates are green, the pebbles then being derived from basic igneous rocks. Other conglomerates have pebbles of quartz.