The Caledonian orogeny was a mountain-building era recorded in the northern parts of the

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...

, the Scandinavian Mountains, Svalbard, eastern Greenland and parts of north-central Europe. The Caledonian orogeny encompasses events that occurred from the

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 ...

to Early Devonian, roughly 490–390 million years ago ( Ma). It was caused by the closure of the Iapetus Ocean when the continents and

terrane In geology, a terrane (; in full, a tectonostratigraphic terrane) is a crust (geology), crust fragment formed on a tectonic plate (or broken off from it) and Accretion (geology), accreted or "Suture (geology), sutured" to crust lying on another pla ...

s of

Laurentia Laurentia or the North American Craton is a large continental craton that forms the ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of North America, althoug ...

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, ...

and Avalonia collided. The orogeny is named for Caledonia, the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

name for

Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...

. The term was first used in 1885 by

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

n geologist

Eduard Suess Eduard Suess (; 20 August 1831 - 26 April 1914) was an Austrian geologist and an expert on the geography of the Alps. He is responsible for hypothesising two major former geographical features, the supercontinent Gondwana (proposed in 1861) and t ...

for an episode of mountain building in northern Europe that predated the Devonian

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

. Geologists like Émile Haug and

Hans Stille Hans Wilhelm Stille (8 October 1876 – 26 December 1966) was an influential German geologist working primarily on tectonics and the collation of tectonic events during the Phanerozoic. Stille adhered to the contracting Earth hypothesis A ...

saw the Caledonian event as one of several episodic phases of mountain building that had occurred during Earth's history. Current understanding has it that the Caledonian orogeny encompasses a number of

tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...

phases that can laterally be diachronous. The name "Caledonian" can therefore not be used for an absolute period of geological time, it applies only to a series of tectonically related events.

Geodynamic history

The Caledonian orogeny was one of several orogenies that would eventually form the

supercontinent In geology, a supercontinent is the assembly of most or all of Earth's continental blocks or cratons to form a single large landmass. However, some geologists use a different definition, "a grouping of formerly dispersed continents", which leav ...

Pangaea Pangaea or Pangea () was a supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from the earlier continental units of Gondwana, Euramerica and Siberia during the Carboniferous approximately 335 million y ...

in the Late

Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

era An era is a span of time defined for the purposes of chronology or historiography, as in the regnal eras in the history of a given monarchy, a calendar era used for a given calendar, or the geological eras defined for the history of Earth. Comp ...

. In the Early Paleozoic the majority of all continental landmasses were united in the paleocontinent of Gondwana, containing the crust of future

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

, southern

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

, Australia and

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest cont ...

, which lay centered on the South Pole. Between 650 and 550 million years ago (in the Ediacaran period) the smaller continents of Laurentia (containing the future northeast section of North America),

and

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive region, geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a ...

had separated from Gondwana to move northward towards the equator. In the process, the Iapetus Ocean between Gondwana, Baltica and Laurentia closed. In the Early

period (about 480 million years ago) the

microcontinent Continental crustal fragments, partly synonymous with microcontinents, are pieces of continents that have broken off from main continental masses to form distinct islands that are often several hundred kilometers from their place of origin. Caus ...

(a small fragment of

continental lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years or ...

) Avalonia (now lithosphere that is scattered over the east of

New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the Can ...

, the south of Newfoundland, parts of

New Brunswick New Brunswick (french: Nouveau-Brunswick, , locally ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. It is the only province with both English and ...

and

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native Eng ...

, southern

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

, most of

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

and

Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...

, the

Low Countries The term Low Countries, also known as the Low Lands ( nl, de Lage Landen, french: les Pays-Bas, lb, déi Niddereg Lännereien) and historically called the Netherlands ( nl, de Nederlanden), Flanders, or Belgica, is a coastal lowland region in N ...

, northern

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

and

Silesia Silesia (, also , ) is a historical region of Central Europe that lies mostly within Poland, with small parts in the Czech Republic and Germany. Its area is approximately , and the population is estimated at around 8,000,000. Silesia is split ...

) began to separate from the northern margin of Gondwana.

Early phases

Some early phases of deformation and/or

metamorphism Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of ch ...

are recognized in the

Scandinavian Caledonides The Scandinavian Caledonides are the vestiges of an ancient, today deeply eroded orogenic belt formed during the Silurian–Devonian continental collision of Baltica and Laurentia, which is referred to as the Scandian phase of the Caledonian or ...

. The first phase that is often included in the Caledonian orogeny is the Finnmarkian phase at 505 million years ago (late Cambrian). Another phase was the Jämtlandian phase at 455 million years ago. These phases are explained by the assumption that the western edge of Baltica collided with an

island arc Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle alon ...

or microcontinent. In a similar way, the eastern edge of Laurentia collided with an island arc during the

Taconic orogeny The Taconic orogeny was a mountain building period that ended 440 million years ago and affected most of modern-day New England. A great mountain chain formed from eastern Canada down through what is now the Piedmont of the East coast of the Unit ...

(from 480 to 435 million years ago). During the Ordovician, the small continent of Avalonia moved independently in a northeastern direction towards Baltica. This motion was accommodated by the subduction of the southeastern Iapetus Ocean (the so-called

Tornquist Sea The Tornquist Sea or Tornquist Ocean was a sea located between the palaeocontinents Avalonia and Baltica about . The remains of the sea today form a suture stretching across northern Europe ( Tornquist Zone). Geologic evolution ...

) beneath eastern Avalonia. In the Late Ordovician (about 450 million years ago) continental collision started between Avalonia and Baltica. The Tornquist Sea disappeared in the process, the remaining suture is the Tornquist line, which runs under the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea, epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the ...

, southern

Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of Denmark , establish ...

and northern Germany and

Poland Poland, officially the Republic of Poland, is a country in Central Europe. It is divided into 16 administrative provinces called voivodeships, covering an area of . Poland has a population of over 38 million and is the fifth-most populou ...

Scandian/Grampian phase

The main phase of the Caledonian orogeny (from about 425 to 400 million years ago) is called the Scandian phase in Scandinavia and the ''Grampian phase'' in the British Isles.Jones & Blake (2003), pp. 47–50 It was caused by the collision between

and

. The Iapetus Ocean first closed in the north, then in the south. Therefore, the collision between Baltica and Laurentia took place a little earlier than that between Avalonia and Laurentia. Continental collision started in the Mid Silurian and mountain building took place in the Early Devonian (from 420–405 million years ago). In North America, the collision between Avalonia and Laurentia is called the Acadian orogeny. According to some authors, the Caledonian continental collisions involved another microcontinent,

Armorica Armorica or Aremorica (Gaulish: ; br, Arvorig, ) is the name given in ancient times to the part of Gaul between the Seine and the Loire that includes the Brittany Peninsula, extending inland to an indeterminate point and down the Atlantic Coast ...

(southern

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

, most of the north of

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

and parts of southern Germany and the

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

), even smaller than Avalonia. This microcontinent probably did not form one consistent unit, but was instead a series of fragments, of which the current Armorican and

Bohemian Massif The Bohemian Massif ( cs, Česká vysočina or ''Český masiv'', german: Böhmische Masse or ''Böhmisches Massiv'') is a geomorphological province in Central Europe. It is a large massif stretching over most of the Czech Republic, eastern Ger ...

s are the most important. The ocean between the combined continental mass of Laurentia, Baltica and Avalonia (called Euramerica, Laurussia or Old Red Continent) and Armorica is called 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 ...

. The paleogeographic position of the Armorica crustal fragments between the Ordovician and Carboniferous is highly disputed though. There are indications that the Bohemian Massif started moving northward from the Ordovician onward, but many authors place the accretion of the Armorican terranes with the southern margin of Laurussia in the Carboniferous

Hercynian orogeny The Variscan or Hercynian orogeny was a geologic mountain-building event caused by Late Paleozoic continental collision between Euramerica (Laurussia) and Gondwana to form the supercontinent of Pangaea. Nomenclature The name ''Variscan'', comes f ...

(about 340 million years ago). The Rhenohercynian basin, a back-arc basin, formed at the southern margin of Euramerica just after the Caledonian orogeny. According to these authors, a small rim from Euramerica rifted off when this basin formed. The basin closed when these Caledonian deformed terranes were accreted again to Laurussia during the Hercynian orogeny.See the reconstructions in Cocks & Torsvik (2006) for this view. Another reconstruction of the collision of Armorica with Euramerica can be found in Stampfli ''et al.'' (2002)

References

Literature

*; 2006
''European geography in a global context from the Vendian to the end of the Palaeozoic''
in: (''eds.''): ''European Lithosphere Dynamics'',

Geological Society of London The Geological Society of London, known commonly as the Geological Society, is a learned society based in the United Kingdom. It is the oldest national geological society in the world and the largest in Europe with more than 12,000 Fellows. Fe ...

Memoirs 32, pp. 83–95. *; 1997: ''The margins of Avalonia'', Geological Magazine 134, pp. 627–636. *; 1998: Timing and kinematics of Caledonian thrusting and extensional collapse, southern Norway: evidence from 40Ar/39Ar thermochronology. Journal of Structural Geology 20, 765-781. *; 2003: ''Mountain building in Scotland'', . *; 2001: ''The Variscan collage and orogeny (480–290 Ma) and the tectonic definition of the Armorica microplate: a review'', Terra Nova 13, 122–128. *; 2000: ''The Caledonian Orogeny redefined'', Journal of the Geological Society 157, pp. 1149–1154. *; 2002: ''The Early Palaeozoic break-up of northern Gondwana, new palaeomagnetic and geochronological data from the Saxothuringian Basin, Germany'', International Journal of Earth Sciences 91(5), pp. 838–849. *; 2002: ''Paleozoic evolution of pre-Variscan terranes: From Gondwana to the Variscan collision'',

Geological Society of America The Geological Society of America (GSA) is a nonprofit organization dedicated to the advancement of the geosciences. History The society was founded in Ithaca, New York, in 1888 by Alexander Winchell, John J. Stevenson, Charles H. Hitch ...

Special Paper 364, pp. 263–28

*; 2004: ''Earth Geography from 400 to 250 Ma: a palaeomagnetic, faunal and facies review'', Journal of the

161, pp. 555–572. *; 2003: ''The Tornquist Sea and Baltica–Avalonia docking'', Tectonophysics 362, pp. 67– 82. *; 1996: ''Continental break-up and collision in the Neoproterozoic and Palaeozoic – A tale of Baltica and Laurentia'', Earth-Science Reviews 40, p. 229–258. *; 1990: ''Geological Atlas of Western and Central Europe'', Royal Dutch Shell, Shell Internationale Petroleum Maatschappij BV (2nd ed.), {{ISBN, 90-6644-125-9.

External links

''Middle Ordovician'' (Continent Map)Re-defining the Caledonian
Ordovician orogenies Silurian orogenies Devonian orogenies Orogenies of Europe Paleozoic Europe Geology of the United Kingdom Geology of Norway Ordovician England Ordovician Norway Silurian England Silurian Norway Devonian England Devonian Norway

Geodynamic history

Early phases

Scandian/Grampian phase

See also

References

Literature

External links