Laurasia

Laurasia ( Laurentia and Asia, also Laurasia ), the northern of the two major land masses in the supercontinent Pangaea in the Mesozoic broke. The southern continent that arose during this separation is called Gondwana. Laurasia consisted of the continents Laurentia, Baltica, Sibiria and the cratons North China and East China. Laurasia had an area of ​​about 65 million square kilometers in the Permian.

Term

The South African geologist Alexander Du Toit has about 1937, the theory of the super-continent Pangea meteorologist Alfred Wegener refined the German and spoken by the two land masses, Laurasia in the north and Gondwana in the south.

Formation

Although Laurasia as Mesozoic continent - as part of Pangaea - known and in the geological theory of plate tectonics is undisputed, is now thought that its constituent parts after the breakup of the supercontinent Rodinia - 800 mya - formed a contiguous large continent. To avoid confusion with the Mesozoic Laurasia, this is also known as Proto - Laurasia.

Probably broke Proto - Laurasia short time apart before it again with southern fragments Rodinias - merged to the late Precambrian supercontinent Pannotia, but the "only" 600-540 mya, ie to the early Cambrian, had inventory - East and West Gondwana.

Apart breakage and reunion

During the Cambrian period - from about 540 mya - was Laurasia in tropical latitudes where secreted northern China and Sibiria the north and in the Ordovician, the first continents for 400 million years ( the division Rodinias ), achieved high northern latitudes.

In Devon - 400 mya - reached North China the Arctic Circle and remained there as the northernmost country in the world, or of forming Pangaea, during the Carboniferous ice age - about 300 mya. Strangely, there is no evidence of large-scale glaciation of the northern continents.

In this cold period took place the Alleghenisch - Appalachian orogeny and the economically important coal deposits of England, Germany and West Virginia were formed.

Siberia moved southwards and came across Kazakhstan, a micro- continent of possibly only in the Silurian - was formed by volcanic activity in the primeval ocean Panthalassa and the Tethys - 430 mya.

The merger of these two continents Laurasia was nearly reunited and at the beginning of the Triassic - 250 mya - also the East China craton, and the last to the northern Chinese Terran Pangaea had to drift from the Arctic to the south, attached.

Last breakup

At the breakup of Pangaea in the Jurassic - about 150 mya - to Laurasia divided by the opening of the North Atlantic in Laurentia (present-day North America ) and Eurasia ( which only in the Cretaceous - anlagerten India and the Arabian Peninsula - 100 mya ). All participating cratons - except for Greenland, Ireland and England - have joined forces to date, however, already shows first Riftzonenbildung in the region of Lake Baikal.