The basement to juvenile greenstone rocks in the Central Tanzania Region includes E-W-trending orthogneisses. These comprise largely >3140 Ma diorite to granodiorite gneisses with rafts and/or tectonic enclaves of supracrustal rocks, including ¡«3600 Ma fuchsitic sericite quartzite, which forms part of the ¡«25 km by 5 km Simba-Nguru Hills in the Undewa-Ilangali Terrane. This quartzite contains detrital 4013-3600 Ma zircons that define ancestral cycles of protracted magmatism in their as yet undetected source terranes.
In addition to the ¡«2815-2670 Ma granitoids and greenstones in the >3000 Ma gneisses and granitoids within the widely accepted marginal zone of the Tanzania Craton, the Lake Nyanza Superterrane extends east into the Kilindi-Handeni Superterrane, in the largely Neoproterozoic Southern East African Orogen. In this Superterrane, Neoarchean igneous and sedimentary rocks in the Mkurumu-Magamba Terrane record ¡«620-603 Ma amphibolite-granulite facies metamorphism, ¡«585-575 Ma partial-melting, and emplacement of enderbitic-charnockitic granitoids. They also record a short-lived, but significant, 570-560 Ma period of exhumation and emplacement of high-grade metamorphic rocks on to basement rocks of the proto-Archean craton within the Central Tectonic Zone in the Southern East African Orogen.