Grunnfjellet omkring Tangen, østsiden av Mjøsa.

Abstract

Petrographic and structural investigations were made in a Precambrian area east of lake Mjøsa, southern Norway. The rocks, mainly granitic and dioritic, are mostly mylonitised and brecciated. Some of the fault zones are younger than Ordovician and are probably parts of the Oslo falult system. Amphibolitic and dioritic inclusions in some of the granites and granodiorites are probably fragments of older gabbros. The mineral combinations of the rocks usually correspond to the epidote amphibolite and epidote amphibolite- greenschist facies. Green hornblende is the prevailing dark mineral in the gabbros. Examples with modal analysis are given for several types of rocks.