THE ASSEMBLY OF GONDWANA 800-550 MA

The formation of the supercontinent Gondwana heralded the beginning of the Phanerozoic following a complex series of collisional events afte r the break-up of earlier supercontinental assemblages. Paleomagnetic data are used to help distinguish between these events and it appears that there are three critical periods of mountain building during Gond wana assembly. The first major orogenic event took place between 800 a nd 650 Ma and has been termed the East Africa Orogeny. This tectonic e pisode formed the Mozambique Belt and likely resulted from the collisi on of India, Madagascar and Sri Lanka with East Africa. The second and third orogenic periods during Gondwana assembly partially overlap in time. The Brasiliano orogeny (600-530 Ma) resulted in the amalgamation of the South American nuclei and Africa. The Kuunga Orogeny was propo sed, in part, because of the recent collection of geochronologic data indicating a 550 Ma granulite forming event in East Gondwana and the o bservation that the apparent polar wander path for Gondwana does not f orm a spatially and temporally coherent pattern until roughly the same time. The Kuunga orogeny may have resulted from the collision between Australia and Antarctica with the rest of Gondwana. (C) 1997 Elsevier Science Ltd.