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 underlie south-west Great Britain, southern Ireland, and the eastern coast of North America. It is the source of many of the older rocks of We ...

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, is ...

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 (; ) was an ocean that existed in the late Neoproterozoic and early Paleozoic eras of the geologic timescale (between 600 and 400 million years ago). The Iapetus Ocean was situated in the southern hemisphere, between the paleoc ...

Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final st ...

, including Avalonia until Early Ordovician, was separate from Baltica throughout the

Cambrian The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ag ...

. It probably closed during the

Late Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

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 paleo-magnetic 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 ...

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 palaeocontinents, Gondwana and Laurussia (Laurentia- Baltica-Avalonia). One of the principal oceans of the Palaeozoic, its sutures today stretch from Mexico to Turkey and its closure result ...

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

Ardennes The Ardennes (french: Ardenne ; nl, Ardennen ; german: Ardennen; wa, Årdene ; lb, Ardennen ), also known as the Ardennes Forest or Forest of Ardennes, is a region of extensive forests, rough terrain, rolling hills and ridges primarily in Be ...

and the Northern

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

Belt originated between the Tornquist Sea and the

during the Ordovician and

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 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 shortest period of the Paleozoi ...

. 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 Wawrzyniec Karol de Teisseyre (1860–1939) was a Polish geologist who is known for his work on the southern part of the Trans European Suture Zone and Galician and Romanian geology. Wawrzyniec Teisseyre was born in Cracow (Poland) of French an ...

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. T ...

(TESZ).

References

Notes

Sources

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