Svekofenniden
The Svekofenniden are a tectonic unit and a former orogen in what is now Scandinavia . They make up a large part of the Baltic Shield .
The Baltic Shield can be divided into four groups of different ages. The archaic Saamids with an age of around 3-2.5 Ga (Faupl, 2003) are located on the North Sea and in East Karelia . Between the Saamids on the White Sea are the Belmorids, which consist of highly metamorphic gneisses that were overprinted 2 Ga ago (Faupl, 2003). Most of the Baltic Shield belongs to the Svekofennids, which were consolidated by orogeny 1.8 Ga ago. This unit stretches from Lake Ladoga to Sweden at the geographic height of Gotland. The youngest part of the shield are the Svekonorwegids. The last orogenesis took place about 1 Ga ago. This area also includes the Trans-Scandinavian Magmatite Belt (TIB). The Jotnian sandstone, which is only occasionally penetrated by postorogenic dykes , is discordant on these units . Today, the Jotnian sandstone is mainly found in the Jotnian Trench, which was formed before 1.5-1.3 Ga.
The Svekofennids are described here using a profile from the Tampere area (Schöneberger, 1997), where the metasediments show the development of a continental margin and ocean. So far, no continental hinterland is known. The rocks of the Svekofenniden consist of leptites , metamorphosed volcanites , meta- flysch and subordinate metapelites , as well as unmetamorphic volcanites (Schöneberger, 1997). The metamorphosis took place mainly at high temperatures and low pressures. In places the sedimentary stratification has been preserved, for example in the approximately 2 Ga old ripples of Västervik.
literature
- Peter Faupl: Historical Geology. An introduction (= UTB . 2149). 2nd, improved edition. facultas wuv, Vienna 2003, ISBN 3-8252-2149-0 .
- Reinhard Schönenberg, Joachim Neugebauer: Introduction to the geology of Europe. 7th, revised edition. Rombach GmbH printing and publishing house, Freiburg im Breisgau 1997, ISBN 3-7930-9147-3 .