PALEOMAGNETIC CONSTRAINTS ON THE RODINIA SUPERCONTINENT - IMPLICATIONS FOR ITS NEOPROTEROZOIC BREAK-UP AND THE FORMATION OF GONDWANA

An interpretation of available paleomagnetic data from the Laurentia, Congo-Sao Francisco, Kalahari, and Amazonia cratons favors the hypothe sis that these units were juxtaposed in a supercontinent by 1000 Ma. T his supercontinent is similar to Hoffman's (1991) Rodinia, except for the Kalahari craton, whose 1300 to 1000 Ma Namaqua-Natal mobile belt i s now juxtaposed against the correlated 1300 to 1000 Ma Grenville belt in eastern Laurentia. Our model suggests that a continuous 1300 to 10 00 Ma orogenic belt, formed by the Grenville, Sunsas, Kibaride-Irumide -Lurio, Namaqua-Natal, and Dronning Maud Land-Coats Land belts, repres ents the suture zone between the Amazonia, Congo-Sao Francisco, Kalaha ri-Grunehogna, and Laurentia blocks. The formation of western Gondwana (from our Rodinia supercontinent) may be accomplished by the closure of the large Mozambique Ocean and the more restricted Adamastor Ocean, combined with some counterclockwise rotation of the Congo-Sao Francis co craton. Rotation of the Congo-Sao Francisco craton can explain the observed oblique convergence and wrench tectonics of Pan African-Brasi liano mobile belts that encircle this craton. The model is also consis tent with the synchroneity between the Rodinia break-up and the assemb ly of Gondwana, as suggested by several authors (Laurentia began to se parate from Rodinia at similar to 625 Ma or later).