Arctica
 Arctica, 2400 Ma (Siderian) | |
| Historical continent | |
|---|---|
| Formed | 2565 Ma |
| Type | Paleocontinent |
| Today part of | |
Arctica,orArctida[1]is a hypothetical ancientcontinentwhich formed approximately 2.565billion years agoin theNeoarcheanera. It was made of Archaeancratons,including theSiberian Craton,with itsAnabar/Aldan shieldsinSiberia,[2]and theSlave,Wyoming,Superior,andNorth Atlanticcratons in North America.[3]Arctica was named byRogers 1996because theArctic Oceanformed by the separation of theNorth AmericanandSiberiancratons.[4]Russian geologists writing in English call the continent "Arctida" since it was given that name in 1987,[1]alternatively theHyperborean craton,[5]in reference to thehyperboreansinGreek mythology.
Nikolay Shatsky(Shatsky 1935) was the first to assume that the crust in the Arctic region was of continental origin.[6]Shatsky, however, was a "fixist" and, erroneously, explained the presence of Precambrian and Paleozoic metamorphic rocks on the New Siberian, Wrangel, and De long Islands withsubduction."Mobilists", on the other hand, also erroneously, proposed that North America had rifted from Eurasia and that the Arctic basins had opened behind a retreating Alaska.[7]
Precambrian continent
[edit]In his reconstruction of thesupercontinent cycle,Rogers proposed that the continentUrformed at about 3Gaand formed EastGondwanain the Middle Proterozoic by accretion toEast Antarctica;Arctica formed around 2.5–2 Ga by the amalgamation of theCanadianand Siberian shields plus Greenland; andAtlanticaformed around 2 Ga by the amalgamation of theWest African Cratonand eastern South America. Arctica then grew around 1.5 Ga by accretion of East Antarctica andBalticato form the supercontinentNena.Around 1 Ga Nena, Ur, and Atlantica collided to form the supercontinentRodinia.[8]
Rogers & Santosh 2003argued that most cratons that were around at 2.5 Ga most likely formed in a single region simply because they were located in a single region in Pangaea, which is the reason Rogers argued for the existence of Arctica. The core of Arctica was the Canadian Shield, whichWilliams et al. 1991namedKenorland.They argued that this continent formed around 2.5 Ga and then rifted before reassembling along the 1.8 GaTrans-HudsonandTaltson-Thelonorogenies. These two orogenies are derived from continental crust (not oceanic crust) and were probably intracontinental, leaving Kenorland intact from 2.5 Ga to the present. Correlations between orogenies in Canada and Siberia remain more controversial.[9]
Laurentiaand Baltica were connected during the Late Palaeoproterzoic (1.7–1.74 Ga) and Siberia later joined them. Paleomagnetic reconstructions indicate that they formed a single supercontinent during the Mesoproterozoic (1.5–1.45 Ga) but paleomagnetic data and geological pieces of evidence also suggest a considerable spatial gap between Siberia and Laurentia and Arctica is thought to be the missing link.[10]
Phanerozoic microcontinent
[edit]The current geological structure of the Arctic Region is the result of tectonic processes during the Mesozoic and Cenozoic (250Mato present) when theAmerasianandEurasianbasins formed, but the presence of Precambrian metamorphic complexes discovered in the 1980s indicated a continent once existed betweenLaurentia,Baltica,andSiberia.[11]
In the reconstruction ofMetelkin, Vernikovsky & Matushkin 2015,Arctica originally formed as a continent during theTonian950 Ma and became part of the supercontinentRodinia.It reformed during the Permian-Triassic 255 Ma and became part ofPangaea.During this period the configuration of Arctica changed and the continent moved from near the Equator to near the North Pole while keeping its position between three major cratons: Laurentia, Baltica, and Siberia.[1][12] An extended magmatic event, theHigh Arctic Large Igneous Province,broke Arctica in part 130–90 Ma, opened theArctic Ocean,and left radiatingdyke swarmsacross the Arctic.[13]
Fragments of this continent include theKara Shelf,New Siberian Islands,northernAlaska,Chukotka Peninsula,Inuit Fold Belt in northern Greenland, and two Arctic underwater ridges, theLomonosovandAlpha-Mendeleev Ridges.More recent reconstructions also include Barentsia (includingSvalbardand Timan-Pechora Plates).[11] Remains of the last continent are now located on theKara SeaShelf,New Siberian Islandsand adjacent shelf,Alaskanorth ofBrooks Ridge,Chukchi Peninsulain easternmost Siberia, and fragments in northernGreenlandandNorthern Canadaand in the submergedLomonosov Ridge.[14]
See also
[edit]- Arctic Alaska-Chukotka terrane– Terrane that includes parts of Alaska, Siberia and the continental shelf between them
- Penokean orogeny
- Timanide Orogen– Orogen that formed during the Neoproterozoic
References
[edit]Notes
[edit]- ^abcVernikovsky & Dobretsov 2015,p. 206
- ^Siberian craton - a fragment of a Paleoproterozoic supercontinent
- ^Rogers 1996,Fig. 4, p. 97
- ^Rogers 1996,p. 97
- ^E.g.Khain, Polyakova & Filatova 2009,Tectonic units and their history, p. 335
- ^Khain & Filatova 2009,p. 1076
- ^Zonenshain & Natapov 1987,Introduction, p. 829
- ^Rogers 1996,Abstract
- ^Rogers & Santosh 2003,Arctica and Kenorland (~2500 Ma), pp. 360–361
- ^Tait & Pisarevsky 2009,p. 37
- ^abVernikovsky et al. 2014,Introduction, pp. 265–266
- ^Vernikovsky & Dobretsov 2015,Fig. 2, p. 208
- ^Ernst & Bleeker 2010,90–130 Ma: northern Canada, initiation of the Arctic Ocean, p. 701, fig. 6b, p.705
- ^Metelkin, Vernikovsky & Matushkin 2015,Introduction, p. 114; Fig. 1, p. 115
Sources
[edit]- Ernst, R.; Bleeker, W. (2010)."Large igneous provinces (LIPs), giant dyke swarms, and mantle plumes: significance for breakup events within Canada and adjacent regions from 2.5 Ga to the Present".Canadian Journal of Earth Sciences.47(5): 695–739.Bibcode:2010CaJES..47..695E.doi:10.1139/E10-025.Retrieved28 March2016.
- Khain, V. E.; Filatova, N. I. (2009). "From Hyperborea to Arctida: The Problem of the Precambrian Central Arctic Craton".Doklady Earth Sciences.428(1): 1076–1079.Bibcode:2009DokES.428.1076K.doi:10.1134/S1028334X09070071.S2CID128422376.
- Khain, V. E.; Polyakova, I. D.; Filatova, N. I. (2009)."Tectonics and petroleum potential of the East Arctic province"(PDF).Russian Geology and Geophysics.50(4): 334–345.Bibcode:2009RuGG...50..334K.doi:10.1016/j.rgg.2009.03.006.Retrieved5 March2016.
- Metelkin, D. V.; Vernikovsky, V. A.; Matushkin, N. Y. (2015)."Arctida between Rodinia and Pangea"(PDF).Precambrian Research.259:114–129.Bibcode:2015PreR..259..114M.doi:10.1016/j.precamres.2014.09.013.Retrieved5 March2016.
- Rogers, J. J. W. (1996). "A history of continents in the past three billion years".Journal of Geology.104(1): 91–107, Chicago.Bibcode:1996JG....104...91R.doi:10.1086/629803.JSTOR30068065.S2CID128776432.
- Rogers, J. J. W.; Santosh, M. (2003)."Supercontinents in Earth History"(PDF).Gondwana Research.6(3): 357–368.Bibcode:2003GondR...6..357R.doi:10.1016/S1342-937X(05)70993-X.Retrieved8 March2016.
- Sankaran, A. V. (2003)."The Supercontinent Medley: Recent Views"(PDF).Current Science.85(8): 1121–1123.Retrieved28 February2016.
- Shatsky, N. S.(1935). "On the tectonics of the Arctic".Geology and Mineral Resources in the North of the USSR(in Russian). Vol. 1. pp. 149–165.
- Tait, J. A.; Pisarevsky, S. A. (2009).Siberia, Laurentia and Baltica in Mesoproterozoic(PDF).2nd International Conference on Precambrian Continental Growth and Tectonism.doi:10.13140/2.1.3432.3840.Retrieved19 March2016.
- Vernikovsky, V. A.; Dobretsov, N. L. (2015)."Geodynamic evolution of the Arctic Ocean and modern problems in geological studies of the Arctic region".Herald of the Russian Academy of Sciences.85(3): 206–212.doi:10.1134/S1019331615030193.S2CID152499653.Retrieved5 March2016.
- Vernikovsky, V. A.; Metelkin, D. V.; Vernikovskaya, A. E.; Matushkin, N. Y.; Lobkovsky, L. I.; Shipilov, E. V. (2014)."Early evolution stages of the arctic margins (Neoproterozoic-Paleozoic) and plate reconstructions"(PDF).Proceedings of the International Conference on Arctic Margins VI.Fairbanks, Alaska.Retrieved19 March2016.
- Williams, H.; Hoffman, P. E.; Lewry, J. F.; Monger, J.W. H.; Rivers, T. (1991). "Anatomy of North America: thematic portrayals of the continent".Tectonophysics.187(1–3): 117–134.Bibcode:1991Tectp.187..117W.doi:10.1016/0040-1951(91)90416-P.
- Zonenshain, L. P.; Natapov, L. M. (1987)."Tectonic History of the Arctic Region from the Ordivician Through the Cretaceous".In Herman, Yvonne (ed.).The Arctic Seas: Climatology, Oceanography, Geology, and Biology.Springer.ISBN9781461306771.Retrieved19 March2016.
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