Atlantica

Atlantica at about 2 Ga. Archean cratons in grey.

Atlantica (Greek: Ατλαντικα; Atlantika) is an ancient continent that formed during the Proterozoic about 2,000 million years ago (two billion years ago, Ga) from various 2 Ga cratons located in what is now West Africa and eastern South America. The name, introduced by Rogers 1996, was chosen because the continent opened up to form the South Atlantic Ocean.

    Formation

    Atlantica formed simultaneously with Nena at about 1.9 Ga from Archaean cratons, including Amazonia in present-day South America, and the Congo, West Africa and North Africa Cratons in Africa.

    Breakup

    Reconstruction of Earth 550 Ma ago showing the cratons of Atlantica forming West Gondwana

    Atlantica separated from Nena between 1.6–1.4 Ga when Columbia — a supercontinent composed of Ur, Nena, and Atlantica — fragmented. Together with continents Nena and Ur and some minor plates, Atlantica formed the supercontinent Rodinia about 1 Ga ago. The rifting of Rodinia between 1–0.5 Ga resulted in the formation of three new continents: Laurasia and East and West Gondwana, of which Atlantica became the nucleus of the latter. During this later stage, the Neoproterozoic era, a Brasiliano-Pan African orogenic system developed. The central part of this system, the Araçuaí-West Congo orogen, has left a distinct pattern of deformations, still present on both sides of the Atlantic.

    See also

    Notes

    References

    • Alkmim, Fernando F.; Marshak, Stephen; Pedrosa-Soares, Antônio Carlos; Peres, Guilherme Gravina; Cruz, Simone Cerqueira Pereira; Whittington, Alan (September 1, 2006). "Kinematic evolution of the Araçuaí-West Congo orogen in Brazil and Africa: Nutcracker tectonics during the Neoproterozoic assembly of Gondwana". Precambrian Research 149 (1-2): 43–64. doi:10.1016/j.precamres.2006.06.007. 
    • Noce, Carlos M.; Pedrosa-Soares, Antônio Carlos; da Silva, Luiz Carlos; Armstrong, Richard; Piuzana, Danielle (2007). "Evolution of polycyclic basement complexes in the Aracuaí Orogen, based on U–Pb SHRIMP data: Implications for Brazil–Africa links in Paleoproterozoic time" (PDF). Precambrian Research (159): 60–78. doi:10.1016/j.precamres.2007.06.001. 
    • Rogers, John J. W. (January 1996). "A History of Continents in the Past Three Billion Years". The Journal of Geology 104 (1): 91–107. Bibcode:1996JG....104...91R. doi:10.1086/629803. JSTOR 30068065. 
    • Sankaran, A. V. (2003). "The supercontinent medley: Recent views" (PDF). Current Science 85 (8): 1121–1123. 
    • Yoshida, Masaru; Windley, Brian F.; Dasgupta, Somnath, eds. (2003). Proterozoic East Gondwana: supercontinent assembly and breakup 206. Geological Society of London. ISBN 1-86239-125-4. 
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