Sedimentary, tectonic and metamorphic features of the Devonian of Røragen, Sør-Trøndelag.

Abstract

An outline is given of the depositional environment of these Lower Devonian rocks following the discovery of various primary sedimentary structures which have provided some evidence of palaeocurrent directions. Tectonic structures are described and it is shown that an early deformation phase, apparently along E-W axes, was accompanied by an uneven weak metamorphism; further extensional strain locally produced phyllonites. Some of the less competent lithologies were then mesoscopically folded along approximately NE-SW axes, and this deformation was followed by ocal thrusting, shearing and faulting. These late Caledonian diastrophic events are most probably of Svalbardian (lowermost Upper Devonian) age, and it is suggested that the main folding of the Oslo region Cambro-Downtonian succession as well as some of the sparagmite basin deformation of south-east Norway may date to the same phase of orogenic movement.