Crustal Age Domains and the Evolution of the Continental Crust in the Mozambique Belt of Tanzania: Combined Sm-Nd, Rb-Sr, and Pb-Pb Isotopic Evidence

older crustal material in most other parts of the Mozambique Belt. Combination of Nd and Sr model ages and Pb isotopes on leached This juxtaposition of ancient with juvenile crustal segments is feldspars reveals distinct model age provinces not recognized previously consistent with an active continental margin setting before or during within the Mozambique Belt of Tanzania. Most boundaries of orogenesis. Correlation with adjacent terranes indicates similar these age domains are overprinted by Neoproterozoic (Pan-African) processes of mixing and limited juvenile addition prevailing throughout tectonism and metamorphism. Granitoids from the Archean craton central Gondwana during the Pan-African orogeny. show Nd model ages of 27-31 Ga and very primitive Pb isotope systematics in feldspars. Amphibolite-facies migmatites and granulites from the Mozambique Belt have similar characteristics, yet their high 208 Pb/ 204 Pb values point to U loss in the Archean, possibly during high-grade metamorphism, and subsequent Pan-KEY WORDS: age province boundaries; crustal evolution; model ages; African reworking. Eclogite-facies metapelites of the Early Prot-Mozambique Belt; Sr-Nd-Pb isotopes erozoic Usagaran Belt likewise exhibit Archean Nd model ages, but higher Pb isotopic ratios are consistent with last recrystallization of feldspar at 2 Ga. Granulites with Nd model ages from 1 to 15 Ga only occur in NE Tanzania; because of their restricted range INTRODUCTION