Trans-Scandinavian magmatite belt

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The Trans-Scandinavian Magmatite Belt (short: TIB, from Eng. Transscandinavian igneous-belt) is a tectonic unit of the Baltic Shield , which consists mainly of granites , rhyolites and andesites .

Map of the Baltic Shield. The TIB ( ) is located between the Svekonorwegiden ( ) and the Svekofenniden  ( ).

The Baltic Shield can be divided into four groups of different ages. On the North Sea and in East Karelia are the archaic Saamids with an age of about 3-2.5 Ga. Between the Saamids are the Belmorids on the White Sea, which consist of highly metamorphic gneisses that were overprinted 2 Ga. 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. 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.

A former terran (small continent) is included in the TIB, the Oskarshamn-Jönköping Belt (OJB). The contact between the OJB and the TIB cannot be established in the field, as it is either covered by the granites and volcanic rocks of the TIB or separated by shear zones. The latter run mainly NW-SE. The OJB stands out from the surrounding granites and porphyries due to the composition of metasedimentites and metavolcanites.

This belt was deformed before the TIB's magmatites intruded 1.81-1.77 Ga. Following the OJB magmatism, magmatism took place in TIB1 (1813–1766 Ma), the lithologies of which, together with those of TIB2 (1723–1691 Ma) and TIB3 (1681–1657 Ma), partially covered the OJB.

Later on, new magmatites formed occasionally, the youngest being 1,450 Ma old.

The magmas of the TIB come from the melting of rocks on destructive plate edges. These magmas led to volcanic and plutonic phenomena of the Andean type.

Individual evidence

  1. ↑ a b Peter Faupl: Historical Geology. An introduction (= UTB . 2149). 2nd, improved edition. facultas wuv, Vienna 2003, ISBN 3-8252-2149-0 .
  2. ↑ a b Annakaisa Korja, Pekka Heikkinen: The accretionary Svecofennian orogen-insight from the BABEL profiles. In: Precambrian Research . Vol. 136, No. 3/4, 2005, pp. 241-268, doi : 10.1016 / j.precamres.2004.10.007 .
  3. ↑ Raimo Lahtinen, Mikko Nironen: Paleoproterozoic lateric paleosol-ultra-mature / mature quarzite-meta-arkose succsessions in southern Fennoscandia-intra-orogenig stage during the Svecofennian orogen. In: Precambrian Research. Vol. 183, No. 4, 2010, pp. 770-790, doi : 10.1016 / j.precamres.2010.09.006 .
  4. ↑ a b Jan Lundqvist, Thomas Lundqvist, Maurits Lindström, Mikael Calner, Ulf Sivhed: Sveriges Geologi från urtid till nutid. 3. Edition. Student literature, Lund 2011, ISBN 978-91-44-05847-4 .