Hovedtrekk av den tektoniske utviklingen i østre del av sparagmittområdet i Sør-Norge

Abstract

The structural history of the esatern Sparagmite area in Norway can be seperated into three main phases: (1) Pre- and early - Caledonian anorogenic movements including rifting and formation ot the eastern sparagmite basin in the Late Precambrian to Lower Ordovicivian and regional epeirogenic movements in the Lower- to Middel Cambrian, in the Lower Ordovician and after the deposition of Llanviranian black shale; (2) Caledonian orogenic movements comprising (a) the thrusting of the Osen nappe and folding of the intrabasinal sequence (pre-Silurian=) (b) the thrusting of Kvitvola and Røa nappes above a folded and eroded parautchtonous sequence (Silurian - Devonian), (c) local upthrusts towards the S and SE, and (d) thrust movements from the NE towards the SW (in the north and northeast) (Svalbardian phase?): (2) post-Caledonian normal faults, acting mostly along older fracture zones. The horisontal shortening due to Caledonian movemens is discussed.