Avalonia is in Earth's history the name of a small continent which broke off in the Lower Ordovician of the northern edge of the southern continent Gondwana and collided with Baltica in Oberordovizium. It now forms the foundation of Northern Germany, the southern North Sea, the Midlands, Wales, Southern Ireland and smaller parts of North America ( Newfoundland, Nova Scotia, New Brunswick, parts of New England and the northern part of Florida ). Today's European parts Avalonias are also known as East Avalonia, now North American parts as West Avalonia. They have been regarded by some authors as two independent terrane.
The name was apparently used by a group of authors to Christopher Scotese in 1979 for the first time. Namesake of Avalonia is the Avalon Peninsula in Newfoundland today. The area was, however, already been recognized earlier as a separate structural tectonic unit of the Appalachians and called Avalon platform or later Avalon zone. In the early 1980s has also been widely used in the literature for the term Avalonia Avalon Terrane.
History of the small continent
In Jungproterozoikum and Lower Paleozoic (ca. 700-480 Mio.J. ) Avalonia was the north ( today's ) South America and the northern part of West Africa upstream, and thus part of the hotel on the southern hemisphere to the south pole positioned supercontinent Gondwana. This union rand parts of Gondwana were recognized in the Late Proterozoic Cadomian orogeny of the ( 650-550 ma).
In Unterordovizium Avalonia broke off in higher southern latitudes of Gondwana and drifted towards the equator on Baltica and Laurentia to. Between Avalonia and Gondwana, the Rheische Ocean opened. North of Avalonia was subducted beneath the eastern part of Avalonia the Tornquist Ocean under the western part of Iapetus. In low southern latitudes Avalonia collided with Baltica in the uppermost Ordovician (today's northern and eastern Europe ). Here, the Tornquist Ocean between Baltica and Avalonia was closed. The line ( " suture " ) is referred to as Tornquist line. In the Silurian Baltica and Avalonia are now connected (today's North America with Greenland, northern Ireland and Scotland) collided with Laurentia at closure of the Iapetus Ocean. The difference resulting from Baltica, Laurentia and Avalonia new super continent is called Laurussia.
Opening of the present-day North Atlantic
The opening of the North Atlantic from south to north in the Mesozoic and Cenozoic ensured that today ( Newfoundland, New England states ) are parts of the former small continent Avalonia in northern central Europe and eastern North America.