Geochronology of granitic rocks from the Ruangwa region, southern Tanzania - Links with NE Mozambique and beyond

Abstract

An area of high grade basement in the Ruangwa District, southern Tanzania was mapped. Four granitoid bodies of varying composition, structure and age sampled for U-Pb zircon dating. Granitoids gave ages of ca. 900, 650, 600 and 550Ma. Study area has affinities with segments to the north (Tanzania-Kenya) and south (Mozambique). New U-Pb zircon LA-ICP-MS data are presented for 4 granitoid bodies which intrude high grade gneisses of the previously unmapped Ruangwa region in southern Tanzania. The study area forms part of the late Neoproterozoic East African Orogen (EAO). The oldest unit, a coarse-grained migmatitic granitic orthogneiss gave an early Neoproterozoic (Tonian) crystallization age of 899±9/16Ma, which is similar to, but significantly younger than, Stenian-Tonian basement ages in areas relatively nearby. Crust of this age may extend as far north as the major Phanerozoic Selous Basin, north of which Archaean protolith ages predominate (the "Western Granulites"), except for...