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. ^[1] The name, introduced by Rogers 1996, was chosen because the continent opened up to form the South Atlantic Ocean. ^[2]

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.^[3]

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. ^[2] 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. ^[1] 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. ^[4][5]

See also

• Plate tectonics

Notes

1. Rogers 1996
2. Sankaran 2003, p. 1122
3. Yoshida, Windley & Dasgupta 2003, p. 16
4. Alkmim et al. 2006, Abstract
5. Noce et al. 2007, p. 60

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.