The Tornquist Sea or Tornquist Ocean was a sea located between the palaeocontinents

Avalonia Avalonia was a microcontinent in the Paleozoic era. Crustal fragments of this former microcontinent are terranes in parts of the eastern coast of North America: Atlantic Canada, and parts of the East Coast of the United States, East Coast of the ...

and

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, i ...

about . The remains of the sea today form a suture stretching across northern Europe ( Tornquist Zone).

Geologic evolution

It probably formed at the same time (c. 600 Ma) as the

Iapetus Ocean The Iapetus Ocean (; ) existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). It was in the southern hemisphere, between the paleocontinents of Laurentia, Baltica and Avalon ...

Gondwana Gondwana ( ; ) was a large landmass, sometimes referred to as a supercontinent. The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia (continent), Australia, Zea ...

, including Avalonia until

Early Ordovician The Early Ordovician is the first epoch (geology), epoch of the Ordovician period, corresponding to the Lower Ordovician series (stratigraphy), series of the Ordovician system. It began after the Cambrian Stage 10, Age 10 of the Furongian epoch o ...

, was separate from Baltica throughout the

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

. It probably closed during the

Late Ordovician The Late Ordovician is the third and final epoch of the Ordovician period, lasting million years and spanning from around 458.2 to 443.1 million years ago. The rocks associated with this epoch are referred to as the Upper Ordovician Series. At ...

at the time of the Shelveian Orogeny of western England. There are faunal, palaeomagnetic, palaeogeographic, and

apparent polar wander Apparent polar wander (APW) is the perceived movement of the Earth's paleomagnetic poles relative to a continent while regarding the continent being studied as fixed in position. It is frequently displayed on the present latitude-longitude map as a ...

path evidence for the timing of closure for Eastern Avalonia (England, Wales and southern Ireland) and Baltica. The Baltica-Avalonia collision also resulted in that the

Rheic Ocean The Rheic Ocean (; ) was an ocean which separated two major paleocontinents, Gondwana and Laurussia ( Laurentia- Baltica- Avalonia). One of the principal oceans of the Paleozoic, its sutures today stretch from Mexico to Turkey and its closure r ...

ceased to expand south of Avalonia around 450 Ma, in huge magmatism in Avalonia, gigantic ash fall in Baltica, and metamorphism in present-day northern Germany.

Present-day suture

The suture resulting from closure of the Tornquist Sea may be seen in eastern England and the

Lake District The Lake District, also known as ''the Lakes'' or ''Lakeland'', is a mountainous region and National parks of the United Kingdom, national park in Cumbria, North West England. It is famous for its landscape, including its lakes, coast, and mou ...

as an arc of igneous rocks belonging to the Ordovician. The volcanic series in eastern England, the

Ardennes The Ardennes ( ; ; ; ; ), also known as the Ardennes Forest or Forest of Ardennes, is a region of extensive forests, rough terrain, rolling hills and ridges primarily in Belgium and Luxembourg, extending into Germany and France. Geological ...

and the Northern

Phyllite Phyllite ( ) is a type of foliation (geology), foliated metamorphic rock formed from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation.Stephen Marshak ''Essentials of Geology'', 3rd ed. I ...

Belt originated between the Tornquist Sea and the

during the Ordovician and

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

. Where Baltica and Avalonia finally collided is now a suture known as the Teisseyre-Tornquist Line or Zone; named after its discoverers, Polish geologist Wawrzyniec Teisseyre and German geologist Alexander Tornquist. This lineament still marks the transition between, on one hand, the East and North European Pre-Cambrian Craton and, on the other hand, the West European and Mediterranean Palaeozoic Orogenes. It is part of a wider deformation zone running across Europe, from the British Isles to the Black Sea, known as the

Trans-European Suture Zone The Trans-European Suture Zone (TESZ), also known as the Tornquist Zone, is the crustal boundary between the Precambrian East European Craton and the Phanerozoic orogens of South-Western Europe. The zone runs from the North Sea to the Black Sea ...

(TESZ).

References

Notes

Sources

* * * * * * {{Refend Historical oceans Ordovician paleogeography Silurian bodies of water Cambrian paleogeography Natural history of Europe