KIBARAN MAGMATISM AND PAN-AFRICAN GRANULITE METAMORPHISM IN NORTHERN MOZAMBIQUE - SINGLE ZIRCON AGES AND REGIONAL IMPLICATIONS

Single zircons from granitoid orthogneisses in the foreland of the Lur io Belt of northern Mozambique were dated by the evaporation method-an d yielded Pb-207/Pb-206 magmatic emplacement ages between 1040.1+/-0.4 and 1148.2+/-0.4 Ma. These data confirm previous Rb-Sr whole rock and SHRIMP zircon analyses and record a period of magmatic activity corre sponding to the Kibaran event of east central Af rica. A similar to 13 00 Ma old zircon xenocryst in one sample suggests the presence of stil l older crust in the region. Metamorphic zircons from a granulite-faci es psammopelitic gneiss of the Mugeba klippe, which is derived tectoni cally from the Lurio. Belt, were dated by evaporation, conventional te chniques and SHRIMP at similar to 615 Ma. This is interpreted as refle cting the peak of high-grade metamorphism in this rock and, by implica tion, in the Lurio Belt. It is concluded from this; that the main meta morphism in the basement of northern Mozambique occured in Pan-African times, as is the case in adjacent regions of Tanzania and Malawi, and that this may be the result of collision between East and West Gondwa na. (C) 1997 Elsevier Science Limited.