Sea between the palaeocontinents Avalonia and Baltica about 600 to 450 million years ago
The Tornquist Sea or Tornquist Ocean was a sea located between the palaeocontinents
Avalonia and
Baltica about 600 to 450 million years ago. The remains of the sea today form a suture stretching across northern Europe (
Tornquist Zone).
Geologic evolution
LEGEND Tectonic framework map of Europe
Baltica
Caledonian (Laurentia)
Caledonian (Baltica)
Avalonia
Hercynian
Alpine
Alps
Carpathians
Ukrainian shield
Pyrenees
Apennines
Dinarides
Atlas
Baltic shield
London-Brabant massif
Cordillera Betica
Tectonic map of Europe; the Teisseyre-Tornquist Zone is located between the
London-Brabant Massif (=Eastern Avalonia) and the
Baltic Shield. The Tornquist Fan stretches across Denmark.
There are faunal, palaeomagnetic, palaeogeographic, and
apparent polar wander path evidence for the timing of closure for Eastern Avalonia (England, Wales and southern Ireland) and Baltica.[2]
The Baltica-Avalonia collision also resulted in that the
Rheic Ocean 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.[3]
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 and the Northern
Phyllite Belt originated between the Tornquist Sea and the
Rheic Ocean during the Ordovician and
Silurian.[1]
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 (TESZ).[4][5]
^Torsvik et al. 1993, Summary;
Torsvik & Rehnström 2003, 8. Avalonia and Baltica convergence and the tale of K-bentonites, pp. 77–80. Torsvik et al. 1993 proposed a "pre-
Wenlock (Early Silurian) collision" but (e.g.) Torsvik & Rehnström 2003 modified the timing to Late Ordovician.