Palaeotethys
The Paleo-Tethys Ocean (also Paleo-Tethys Ocean) was in the earth's originally west-east running ocean between the continents Laurussia the north and Gondwana in the south, which from the Upper Silurian opened and in the Lower Carboniferous reached its greatest extent had. It was the forerunner of the Tethys , also called Neotethys, which opened from the Permian in about the same room, during which the Palaeotethys was gradually subducted under Laurasia . With the collision of Gondwana and Laurussia in the Upper Carboniferous, the Paleotethys was closed to the west and, after the collision of the Paleo-Asiatic continental block (including Siberia, Kazakhstan) with Gondwana-Laurussia, formed a bay in the east of the supercontinent Pangea that was created .
Development of the Palaeotethys
In the Obersilur , the Hun superterran began to break off from the northern edge of Gondwana and to drift north towards Laurussia . It was probably not a contiguous small continent, as initially assumed, but several smaller blocks of crust that also moved slightly against each other. The western part of the European Hun Terrane is the Armorica -Terrang group. During this north migration, the Rheic Ocean was subducted north of the Hun superterrans under Laurussia . The Rhine Ocean closed noticeably until Armorica collided with Laurussia in the early Upper Carboniferous and thus initiated the main phase of the Variscan orogeny in Europe.
The ocean basin that opened up between the Hun super terran and Gondwana is the Palaeotethys. This reached its greatest extent in the Lower Carboniferous. In the Upper Carboniferous it was closed in the west by the collision of Gondwana with Laurussia, in the course of which further mountain ranges formed, which, including the European Variscides, are known as the Hercynian system. The westernmost point of the Paleotethys was at this time roughly in the area of southwest Europe / northwest Africa. From there it widened to the east like a wedge. A wreath of small continents (including today's China and Southeast Asia) and arches of islands separated it from the Panthalassa , the "primordial Pacific", from the Upper Carboniferous to far into the Permian .
Closure of the Palaeotethys
At the beginning of Perm another small continent split off from the eastern northern edge of Gondwana, Kimmeria , also called Kimmeria Super Terran, who drifted during the Permian and Triassic north on Laurasia, the northern part of Pangea, too. A new ocean basin opened up between Gondwana and Cimmeria , the Neotethys, traditionally also simply called Tethys . In the north, the Palaeotethys was increasingly subducted under the southern edge of Laurasia. At the same time, the Neotethys expanded to the west during the Triassic - one of numerous processes that led to the disintegration of the Pangea . So began z. B. in the Upper Triassic (in places already in the Middle Triassic) also the first phase of the formation of the Central Atlantic with the sinking of rifts between today's North America and today's West Africa (including → Newark Supergroup ). The closure of the Palaeotethys took place at the turn of the Triassic - Jurassic period due to the clash of the Cimmerian Terrane with Laurasia and the formation of the Cimmerian fold belt .
The so-called Balkan Kimmeriden form the only section of the Cimmerian fold belt that is in Europe today. The interface of the collision runs today from the Black Sea southwest through southern Bulgaria to Chalkidiki and then via Macedonia to Kosovo and Serbia . It should be noted, however, that this corresponds neither to the original location nor to the original geometry of the Balkan Kimmerids, as both were changed by the later Alpid mountain formation .
Others
In the older literature, there is often no distinction between the Palaeotethys and the subsequent (Neo-) Tethys . However, according to the more recent plate tectonic models, these are two different oceans that occupied roughly the same paleogeographical position.
Alternative plate tectonic models explain the Variscan mountain formation without the involvement of an Armorican Terran detached from Gondwana, and assume a direct collision between Gondwana and Central Europe.
literature
- LRM Cocks and TH Torsvik: European geography in a global context from the Vendian to the end of the Palaeozoic. In: DG Gee and RA Stephenson (eds.): European Lithosphere Dynamics. Geological Society London Memoirs, 32: 83-95, London 2006 ISSN 0435-4052
- Gérard M. Stampfli, Jürgen F. von Raumer and Gilles D. Borel: Paleozoic evolution of pre-Variscan terranes: From Gondwana to the Variscan collision. Geological Society of America Special Paper, 364: 263-280, Boulder 2002 PDF
Web links
References and comments
- ^ Paul E. Olsen: Stratigraphic Record of the Early Mesozoic Breakup of Pangea in the Laurasia-Gondwana Rift System. Annual Review of Earth and Planetary Sciences, Vol. 25, 1997, p. 337 DOI: 10.1146 / annurev.earth.25.1.337
- ↑ Map of the tectonic provinces ("mountain areas") of Europe. The graphic does not take into account the fact that more recent mountain formations have at least partially overprinted older provinces or are pushed onto them. This means, among other things, that the expansion of older provinces may have been greater than shown.
- ↑ Uwe Kroner, Torsten Hahn: Sedimentation, Deformation and Metamorphosis in the Saxothuringian Age during the Variscan Orogeny: The Complex Development of North Gondwana during Continental Subduction and Leaning Collision . In: Geologica Saxonica. 48/49, 2003, pp. 133-146