Vaalbara

Vaalbara
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Vaalbara is the Earth's theorized first supercontinent. According to radiometric data of the encompassing cratons that constituted Vaalbara, it is believed to have existed 3.3 billion years ago (3.3 Ga) and possibly as far back as 3.6 Ga. Evidence includes geochronological and palaeomagnetic studies between the two Archaean cratons (protocontinents) called the Kaapvaal craton (the Kaapvaal province of South Africa) and the Pilbara craton (the Pilbara region of Western Australia).

Further evidence is the structural sequence similarities of the greenstone belts and gneiss belts of these two cratons. These same Archaean greenstone belts are now spread out across the margins of the Superior craton of Canada and are also spread out across the cratons of the former Gondwana and Laurasia continents. The subsequent drift paths of the Kaapvaal and Pilbara cratons after 2.8 Ga gives further evidence that they were once connected.

It is not certain when Vaalbara began to break up, but geochronological and palaeomagnetic evidence show that the two cratons had a rotational 30-degree latitudinal separation at 2.78 to 2.77 Ga, implying that they were no longer contiguous after ~2.8 Ga.

Bailey, R.C., Cruden, A.R., and B. Nitescu. (2006) "Crustal structure and implications for the tectonic evolution of the Archean Western Superior craton from forward and inverse gravity modeling." Tectonics, vol. 25. Online Abstract: http://www.agu.org/pubs/crossref/2006/2004TC001717.shtml
Dann, J., M. J. de Wit, S. H. White, and E. Zegers. (1998) Vaalbara, Earth's oldest assembled continent? A combined. structural, geochronological, and palaeomagnetic test." Online: http://www.geo.uu.nl/Research/Paleomagnetism/publications/Zegers98b.pdf
Wingate, M.T.D. (1998) “palaeomagnetic test of the Kaapvaal-Pilbara (Vaalbara) connection at 2.78 Ga.” South African Journal of Geology; December 1998; v. 101; no. 4; p. 257-274 Australian National University, Research School of Earth Sciences, Canberra, Australia. Online Abstract: http://sajg.geoscienceworld.org/cgi/content/abstract/101/4/257
Zegers, T.E., and A. Ocampo. (2003) "Vaalbara and Tectonic Effects of a Mega Impact in the Early Archaen 3470 Ma." European Space Agency, ESTEC, SCI-SB, Keplerlaan 1, 2201 AZ Noordwijk. Online: http://www.lpi.usra.edu/meetings/largeimpacts2003/pdf/4038.pdf