Baltica
Baltica is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe north of the Trans-European Suture Zone and west of the Ural Mountains.
The thick core of Baltica, the East European Craton, is more than three billion years old and formed part of the Rodinia supercontinent at c. 1 Ga.[1] Baltica formed at c. 2.0–1.7 Ga by the collision of three Archaean-Proterozoic continental blocks: Fennoscandia (including the exposed Baltic Shield), Sarmatia (Ukrainian Shield and Voronezh Massif), and Volgo-Uralia (covered by younger deposits).
[3] 750–600 million years ago, Baltica and Laurentia rotated clockwise together and drifted away from the Equator towards the South Pole where they were affected by the Cryogenian Varanger glaciations.
Laurentia quickly moved northward into low latitudes but Baltica remained an isolated continent in the temperate mid-latitudes of the Southern Hemisphere, closer to Gondwana, on which endemic trilobites evolved in the Early and Middle Ordovician.
[4][5] During the Ordovician, Baltica moved northward, approaching Laurentia, which again allowed trilobites and brachiopods to cross the Iapetus Ocean.
[14] The presence of micro-diamonds in two islands in western Norway, Otrøya and Flemsøya, indicate that this margin of Baltica was buried c. 120 km (75 mi) for at least 25 million years around 429 Ma shortly after the Baltica-Laurentia collision.
The Baltica-Laurentia suture stretching northeast from the triple junction was deformed in the Late Cambrian in the Scandinavian Caledonides as well as in the Scandian Orogeny during the Silurian.
[16] The eastern margin, the Uralide orogen, extends 2,500 km (1,600 mi) from the Arctic Novaya Zemlya archipelago to the Aral Sea.
[17] The basement of the eastern margin is composed of an Archaean craton, metamorphosed rocks at least 1.6 Ga old, which is surrounded by the fold belt of the Timanide orogeny and overlain by Mesoproterozoic sediments.
[19] Baltic endemic faunas from the Early Ordovician have been found in Kazakhstan near the southern end of the eastern margin, or the triple junction between Baltica, the Mangyshlak Terrane, and the accretionary Altaids.
