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Baltica
Baltica
is a paleocontinent that formed in the Paleoproterozoic and now constitutes northwestern Eurasia, or Europe
Europe
north of the Trans-European Suture Zone
Trans-European Suture Zone
and west of the Ural Mountains.

Contents

1 Tectonic history 2 Margins

2.1 Northern margin 2.2 Southern margin 2.3 Western Margin 2.4 Eastern margin

3 See also 4 References

4.1 Notes 4.2 Sources

Tectonic history[edit]

1.1 Ga Baltica
Baltica
was located in what is now the South Pacific. (Current location of Australia added for reference.)

550 milllion years ago Baltica
Baltica
(green) was an isolated continent located near the South Pole.

Baltica
Baltica
formed at c. 2.0–1.7 Ga by the collision of three Archaean-Proterozoic continental blocks: Fennoscandia
Fennoscandia
(including the exposed Baltic Shield), Sarmatia ( Ukrainian Shield
Ukrainian Shield
and Voronezh Massif), and Volgo-Uralia
Volgo-Uralia
(covered by younger deposits). Sarmantia and Volgo-Uralia
Volgo-Uralia
formed a proto-craton (sometimes called "Proto-Baltica")[1] at c. 2.0 Ga which collided with Fennoscandia c. 1.8–1.7 Ga. The sutures between these three blocks were reactivated during the Mesoproterzoic and Neoproterozoic.[2] 750-600 Ma Baltica
Baltica
and Laurentia
Laurentia
rotated clockwise together and drifted away from the Equator towards the South Pole where they were affected by the Cryogenian Varanger glaciations. Initial rifting between the two continents is marked by the c. 650 Ma Egersund dike swarm in southern Norway and from 600 Ma they began to rotate up to 180° relative to each other, thus opening the Iapetus Ocean between them. Laurentia
Laurentia
quickly moved northward but Baltica remained an isolated continent in the Southern Hemisphere closer to Gondwana
Gondwana
on which endemic trilobites evolved in the Early Ordovician.[3] During the Ordovician Baltica
Baltica
moved northward approaching Laurentia again allowing trilobites and brachiopods to cross the Iapetus Ocean and form the Caradoc Series. In the Silurian, c. 425 Ma, the final collision between Scotland-Greenland and Norway resulted in the Scandian Orogeny.[3] Margins[edit] Baltica
Baltica
is a very old continent and its core is a very well-preserved and thick craton. Its current margins, however, are the sutures that are the result of mergers with other, much younger continental blocks. These often deformed sutures do not represent the original, Precambrian–Early Palaeozoic extent of Baltica; for example, the curved margin north of the Urals running parallel to Novaya Zemlya
Novaya Zemlya
was probably deformed during the eruption of the End-Permian Siberian Traps.[4] Baltica's western margin is the Caledonide orogen which stretches northward from the Scandinavian Mountains
Scandinavian Mountains
across Barents Sea
Barents Sea
to Svalbard. Its eastern margin is the Timanide orogen which stretches north to the Novaya Zemlya
Novaya Zemlya
archipelago.[5] The extent of the Proterozoic continent are defined by the Iapetus Suture
Iapetus Suture
to the west; the Trollfjorden-Komagelva Fault Zone in the north; the Variscan-Hercynian suture to the south; the Tornquist Zone
Tornquist Zone
to the southwest; and the Ural Mountains
Ural Mountains
to the east.[6] Northern margin[edit] Terranes of the North American Cordillera, including Alaska-Chukotka, Alexander, Northern Sierra, and Eastern Klamath, share a rift history with Baltica
Baltica
and most likely were part of Baltica
Baltica
from the Caledonian orogeny to the formation of the Ural Mountains.[7] These terranes can be linked to either northeastern Laurentia, Baltica, or Siberia because of a similar sequence of fossils; detrital zircon from 2-1 Ga-old sources and evidence of Grenvillian magmatism; and magmatism and island arcs from the Late Neoproterozoic and Ordovician-Silurian.[8] Southern margin[edit] From at least 1.8 Ga to at least 0.8 Ga the southwestern margin of Baltica
Baltica
was connected to Amazonia while the southeast margin was connected to the West African Craton. Baltica, Amazonia, and West Africa
Africa
rotated 75° clockwise relative to Laurentia
Laurentia
until Baltica
Baltica
and Amazonia collided with Laurentia
Laurentia
in the 1.1-0.9 Ga Grenville-Sveconorwegian-Sunsás orogenies to form the supercontinent Rodinia. When the break-up of Rodinia
Rodinia
was complete c. 0.6 Ga Baltica
Baltica
became an isolated continent — a 200 million year period when Baltica
Baltica
was truly a separate continent.[9] Laurentia
Laurentia
and Baltica
Baltica
formed a single continent until 1.265 Ga which broke up some time before 0.99 Ga. After the subsequent closure of the Mirovoi Ocean Laurentia, Baltica
Baltica
and Amazonia remained merged until the opening of the Iapetus Ocean
Iapetus Ocean
in the Neoproterozoic.[10] Western Margin[edit] The Western Gneiss Region in northern Norway is composed of 1650-950 Ma-old gneisses overlain by continental and oceanic allochtons that were transferred from Laurentia
Laurentia
to Baltica
Baltica
during the Scandian orogeny. The allochtons were accreted to Baltica
Baltica
during the closure of the Iapetus Ocean
Iapetus Ocean
c. 430-410 Ma; Baltica's basement and the allochtons were then subducted to UHP depth c. 425-400 Ma; and they were finnaly exhumed to their present location c. 400-385 Ma.[11] The presence of micro-diamonds in two islands in northern Norway, Otrøya
Otrøya
and Flemsøya, indicate that this margin of Baltica
Baltica
was buried c. 120 km (75 mi) for at least 25 million years around 429 Ma shortly after the Baltica- Laurentia
Laurentia
collision.[12] Eastern margin[edit] The eastern margin, the Uralide orogen, extends 2,500 km (1,600 mi) from the Arctic Novaya Zemlya
Novaya Zemlya
archipelago to the Aral Sea. The orogen contains the record of at least two collisions between Baltica
Baltica
and intra-oceanic island arcs before the final collision between Baltica
Baltica
and Kazakhstania-Siberia during the formation of Pangaea. The Silurian-Devonian island arcs were accreted to Baltica along the Main Uralian Fault, east of which are metamorphosed fragments of volcanic arc mixed with small amounts of Precambrian and Paleozoic continental rocks. No Rocks, however, unambiguously originating from either Kazakhstania or Siberia have been found in the Urals.[13] The basement of the eastern margin is composed of an Archaean craton, metamorphosed rocks at least 1.6 Ga-old, which is surrounded by the fold belt of the Timanide orogeny and overlain by Mesoproterozoic sediments. The margin became a passive margin facing an Ural Ocean in the Cambrian-Ordovician.[14] See also[edit]

Baltic Plate East European Craton

References[edit] Notes[edit]

^ E.g. Torsvik & Cocks 2005, Norway’s earliest times, pp. 74–75 ^ Bogdanova et al. 2008, The crustal segments of the East European Craton, pp. 2–3 ^ a b Torsvik et al. 1996, Abstract ^ Cocks & Torsvik 2005, The margins of Baltica, p. 41 ^ Gee, Bogolepova & Lorenz 2006, p. 507 ^ Torsvik et al. 1992, Introduction, pp. 133–137 ^ Miller et al. 2011, Abstract ^ Colpron & Nelson 2009, Terranes of Siberian, Baltican and Caledonian affinities, pp. 280–281 ^ Johansson 2009, Abstract ^ Cawood & Pisarevsky 2017, Abstract ^ Hacker et al. 2010, Western Gneiss Region, pp. 150–151 ^ Spengler et al. 2009, Abstract; Conclusion and implications, pp. 33–34 ^ Brown et al. 2006, Geological framework of the Uralides, p. 262; For a model of the arc-continent collsion see Puchkov 2009, Fig. 12, p. 178; Fig. 14, p. 180 ^ Brown et al. 2006, The Paleozoic continental margin of Baltica
Baltica
in the Southern Urals, pp. 262–266

Sources[edit]

Bogdanova, S. V.; Bingen, B.; Gorbatschev, R.; Kheraskova, T. N.; Kozlov, V. I.; Puchkov, V. N.; Volozh, Y. A. (2008). "The East European Craton (Baltica) before and during the assembly of Rodinia" (PDF). Precambrian Research. 160 (1-2): 23–45. doi:10.1016/j.precamres.2007.04.024. Retrieved 28 March 2018.  Brown, D.; Spadea, P.; Puchkov, V.; Alvarez-Marron, J.; Herrington, R.; Willner, A. P.; Hetzel, R.; Gorozhanina, Y.; Juhlin, C. (2006). "Arc–continent collision in the Southern Urals" (PDF). Earth-Science Reviews. 79 (3-4): 261–287. doi:10.1016/j.earscirev.2006.08.003. Retrieved 1 April 2018.  Cawood, P. A.; Pisarevsky, S. A. (2017). "Laurentia-Baltica-Amazonia relations during Rodinia
Rodinia
assembly" (PDF). Precambrian Research. 292: 386–397. doi:10.1016/j.precamres.2017.01.031. Retrieved 1 April 2018.  Cocks, L. R. M.; Torsvik, T. H. (2005). " Baltica
Baltica
from the late Precambrian to mid-Palaeozoic times: the gain and loss of a terrane's identity" (PDF). Earth-Science Reviews. 72 (1-2): 39–66. doi:10.1016/j.earscirev.2005.04.001. Retrieved 7 April 2018.  Colpron, M.; Nelson, J. L. "A Palaeozoic Northwest Passage: Incursion of Caledonian, Baltican and Siberian terranes into eastern Panthalassa, and the early evolution of the North American Cordillera" (PDF). Geological Society, London, Special
Special
Publications. 318 (1): 273–307. doi:10.1144/SP318.10. Retrieved 1 April 2018.  Gee, D. G.; Bogolepova, O. K.; Lorenz, H. (2006). "The Timanide, Caledonide and Uralide orogens in the Eurasian high Arctic, and relationships to the palaeo-continents Laurentia, Baltica
Baltica
and Siberia" (PDF). Geological Society, London, Memoirs. 32 (1): 507–520. doi:10.1144/GSL.MEM.2006.032.01.31. Retrieved 31 March 2018.  Hacker, B. R.; Andersen, T. B.; Johnston, S.; Kylander-Clark, A. R.; Peterman, E. M.; Walsh, E. O.; Young, D. (2010). "High-temperature deformation during continental-margin subduction & exhumation: The ultrahigh-pressure Western Gneiss Region of Norway" (PDF). Tectonophysics. 480 (1-4): 149–171. doi:10.1016/j.tecto.2009.08.012. Retrieved 1 April 2018.  Johansson, Å. (2009). "Baltica, Amazonia and the SAMBA connection—1000 million years of neighbourhood during the Proterozoic?". Precambrian Research. 175 (1-4): 221–234. doi:10.1016/j.precamres.2009.09.011. Lay summary (12 May 2017).  Miller, E. L.; Kuznetsov, N.; Soboleva, A.; Udoratina, O.; Grove, M. J.; Gehrels, G. (2011). " Baltica
Baltica
in the Cordillera?" (PDF). Geology. 39 (8): 791–794. doi:10.1130/G31910.1. Retrieved 1 April 2018.  Puchkov, V. N. (2009). "The evolution of the Uralian orogen" (PDF). Geological Society, London, Special
Special
Publications. 327 (1): 161–195. doi:10.1144/SP327.9. Retrieved 1 April 2018.  Spengler, D.; Brueckner, H. K.; van Roermund, H. L.; Drury, M. R.; Mason, P. R. (2009). "Long-lived, cold burial of Baltica
Baltica
to 200 km depth" (PDF). Earth
Earth
and Planetary Science Letters. 281 (1-2): 27–35. doi:10.1016/j.epsl.2009.02.001. Retrieved 1 April 2018.  Torsvik, T. H.; Cocks, L. R. M. (2005). "Norway in space and time: a centennial cavalcade" (PDF). Norwegian Journal of Geology/Norsk Geologisk Forening. 85: 73–86. Retrieved 1 April 2018.  Torsvik, T. H.; Smethurst, M. A.; Meert, J. G.; Van der Voo, R.; McKerrow, W. S.; Brasier, M. D.; Sturt, B. A.; Walderhaug, H. J. (1996). "Continental break-up and collision in the Neoproterozoic and Palaeozoic—a tale of Baltica
Baltica
and Laurentia" (PDF). Earth-Science Reviews. 40 (3-4): 229–258. doi:10.1016/0012-8252(96)00008-6. Retrieved 31 March 2018.  Torsvik, T. H.; Smethurst, M. A.; Van der Voo, R.; Trench, A.; Abrahamsen, N.; Halvorsen, E. (1992). "Baltica. A synopsis of Vendian-Permian palaeomagnetic data and their palaeotectonic implications" (PDF). Earth-Science Reviews. 33 (2): 133–152. doi:10.1016/0012-8252(92)90023-M. Retrieved 1 April 2018. 

v t e

Continents of the world

   

Africa

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Asia

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Europe

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Afro-Eurasia

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Former supercontinents Gondwana Laurasia Pangaea Pannotia Rodinia Columbia Kenorland Nena Sclavia Ur Vaalbara

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Mythical and hypothesised continents Atlantis Kumari Kandam Lemuria Meropis Mu Hyperborea Terra Australis

See also Regions of the world Continental fragment

.