DISCRETE METAMORPHIC EVENTS IN THE LIMPOPO BELT, SOUTHERN AFRICA - IMPLICATIONS FOR THE APPLICATION OF P-T PATHS IN COMPLEX METAMORPHIC TERRAINS

Essentially all models for the tectonic evolution of the high-grade Li mpopo belt of southern Africa invoke a single orogenic event at 2.7 Ga involving the collision of the Zimbabwe and Kaapvaal cratons with a d istinct central zone. By implication, rocks within the belt must have followed parallel pressure-temperature-time (P-T-t) paths. The main re asons for this situation are the belief that syn- to postdeformational granitic magmatism in the belt was coeval and the fact that P-T paths are similar. New geochronological data indicate, however, that this m agmatism occurred at distinct times in different parts of the belt ove r a span of at least 70 m.y. In addition, the data indicate that high- grade meta-morphism and associated tectonism in the central and southe rn marginal zones occurred at about 2.0 and 3.15 Ga, respectively. The refore, P-T-t paths of these zones were independent until their juxtap osition more recently than 2.0 Ga.