Svecofennian orogeny

[3] To the west and southwest the Svecofennian orogen limits with the generally younger Transscandinavian Igneous Belt.

[4] It is assumed that the westernmost fringes of the Svecofennian orogen have been reworked by the Sveconorwegian orogeny just as the western parts of the Transscandinavian Igneous Belt has.

[5] The Svecofennian orogeny involved the accretion of numerous island arcs in such manner that the pre-existing craton grew with this new material from what is today northeast to the southwest.

The closure of this basin was indebted to subduction and resulted thus both in the formation of igneous rocks and the emplacement of the Jormua and Outokumpu ophiolites about 1950 million years ago.

[6] The stage to the Fennian orogeny was set by a collision between Keitele and Karelia about 1920–1910 million years ago which resulted in a reorganization of the local plate tectonics.

[6] The until then linear Fennian orogen was "buckled" from 1870 million years ago onwards due to an orthogonal change in tectonic compressive stress.

[9] Prior to the Svecobaltic orogeny proper there was period of northward-directed subduction at what is now south-central Sweden and southern Finland.

The orogen at southern Finland with its presumed mountains and thick continental crust collapsed under the influence of gravity and spread out.

This last event of basin inversion was associated with a period of metamorphism in southern Finland that peaked about 1820 million years ago.

Geological map of the Scandinavian Peninsula and Fennoscandia : the Svecofennian orogen is shown in yellow. The blue areas to the west are the Transscandinavian Igneous Belt . The nappes emplaced by the much younger Caledonian orogeny are shown in light green.
Map showing the large-scale geological units of Finland. The Svecofennian orogen (4) is shown in violet blue. The Older Karelian Domain (3) is orange coloured. Areas younger than the Svecofennian orogen are in white.