Transscandinavian Igneous Belt

The Transscandinavian Igneous Belt (Swedish: Transskandinaviska magmatiska bältet), abbreviated TIB, is one of the major lithological units of the Baltic Shield. It consists of a series of batholiths in Sweden and Norway forming a ca. 1400 km long belt running from Lofoten, Norway, in the north to Blekinge, Sweden, in the south. The Transscandinavian Igneous Belt and its rocks solidified from magma between 1810 and 1650 million years ago during the Mesoproterozoic. The Transscandinavian Igneous Belt was likely formed in a Andean-type geological environment, implying it was once parallel to a destructive plate boundary. The belt was first identified in the 1980s and was referred as the "Transscandinavian Granite-Porphyry Belt". The current name was first applied in 1987.

The Transscandinavian Igneous Belt occurs as a ca. 1400 km long belt running from Lofoten in the north to Blekinge in the south. The northern parts of the belt are partly covered Caledonian nappes but crop out in windows (e.g. Rombak, Nasafjället). In addition to this some Caledonian nappes are made up of Transscandinavian Igneous Belt rocks. Beneath the East European Platform the belt continues across the Baltic Sea to northeast Poland and Kaliningrad Oblast.

The plutons of the belt formed variously between 1810 and 1650 million years ago (Mya) the oldest rocks overlapping in age with the rocks of the Svecofennian orogeny and the youngest overlapping in age with the deformation and metamorphism of the Gothian orogeny. The igneous activity of the Transscandinavian Igneous Belt is periodized into three age groups; TIB 1 (1813–1766 Mya), TIB 2 (1723–1691 Mya) and TIB 3 (1681–1657 Mya). This periodization is not perfect as it excludes the youngest units formed 1450 million years ago.

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