Beskrivelse til berggrunnsgeologisk kart over strøket Agdenes- Hemnefjord, Sør-Trøndelag.

Abstract

The area consists of regional metamorphic gneisses and crystalline schists. Some of the rocks are of Cambrian-Ordovician age, others of Precambrian age. Examples on the former are flagstones (metamorphosed \"sparagmite\") and large masses of amphibolite (probably corresponding to the Ordovician Støren greenstone). Many of the gneisses which occur as core fillings in antiforms are believed tobe of Precambrian age, probably representing the bobilized basement to the Caledonian geosynclinal column ofsediments and lavas. The latter are chiefly found in more or less tightly synforms between the antiforms. All rocks, exept the Devonian sediments along the NV edge of the map, are deformed and regionally metamorphosed in Caledonian time. It is therefore difficult to distinguish between basement and cover, particulary since the latter contains arkose (sparagmite) which in regional metamorphic version becomes mineralogically identical with some basement gneisses. The structure is characterized by gently plunging fold axes toward ENE and a strong stretching along the fold axes. Structures are found which indicate that the seemingly simple folding is quite complex, involving thight recumbent folds which are folded in more gentle syn- and antiforms.