Validating the existence of Vaalbara in the Neoarchean

An interesting aspect of Precambrian geology is the similarities between successions of the Kaapvaal and Pilbara cratons of southern Africa and Australia. Coeval trends in these successions are commonly used to reconstruct global atmospheric and oceanic conditions during the Archean-Proterozoic transition. The similarities, however, could also suggest their paleogeographic proximity in the form of a supercraton, or even Earth's oldest assembled continent, named Vaalbara. If these cratons indeed were nearest neighbours in a supercraton, the parallel trends preserved in supracrustal sequences may reflect local effects in a single basin instead of global paleoenvironmental conditions. Here we report a paleomagnetic pole from the Neoarchean Ventersdorp Supergroup of South Africa, which provide quantitative support for Vaalbara's existence. Our reconstruction differs greatly from earlier suggestions and contests those that place the cratons far apart. It provides the oldest example, and the only Archean instance, of paleomagnetic reconstruction between continental blocks in terms of paleolatitude and relative longitude. If correct, our reconstruction implies that previous paleoenvironmental conclusions may need reconsideration. (C) 2009 Elsevier B.V. All rights reserved.