Felsic metavolcanics associated with supracrustal rocks provide U-Pb zircon and Sm -Nd T DM ages of approximately 3.3 Ga, which establish an Archean age of the Mundo Novo greenstone belt. A granodioritic gneiss from the Mairi complex, located on the eastern boundary of the Mundo Novo greenstone belt, exhibits a zircon evaporation minimum age of 3.04 Ga and a Nd model age of 3.2 Ga. These results constrain the occurrence of at least three major geological units in this area: the Archean Mundo Novo greenstone belt, the Archean Mairi gneisses, and the adjoining Paleoproterozoic (, 2.1 Ga) Jacobina sedimentary basin. The Jacobina basin follows the same trend as the Archean structure, extending southward to the Contendas -Mirante belt, in which a similar Archean -Paleoproterozoic association appears. We postulate that during the Paleoproterozoic in the eastern margin of the Gavião block, these Archean greenstone belts constituted a zone of weakness along which a late-stage orogenic sedimentary basin developed.

The Salvador-Curaçá Belt, located in São Francisco Craton, Brazil, was subjected to granulite facies metamorphism during the Paleoproterozoic orogeny (c. 2.0 Ga). Well preserved in enclaves of silicaundersaturated sapphirine-bearing granulite occur in a charnockite outcrop located along a kilometric-scale shear zone. The sapphirine-bearing granulite preserves domains with distinct mineral assemblages that record interactions between melt and peritectic phases (orthopyroxene 1 + spinel 1 + biotite 1). Sapphirine was crystallized in the Si-poor cores of the enclaves, sillimanite and spinel-cordierite symplectites in the intermediate Si-rich domains between cores and margins, and garnet and quartz-bearing cordierite/biotite symplectites in Si-rich margins of the enclaves. Melt-rock interactions and metamorphism occurred at ultrahigh temperatures of 900-950°C at 7.0-8.0 kbar pressures. The mineralogical evolution of the domains reflects not only the influence of changes in bulk composition in the equilibrium volume of the reactions but also P-T changes during orogeny evolution. Electron microprobe dating of monazite both in the sapphirinebearing granulite and charnockite indicates UHT metamorphism timing at c. 2.08-2.05 Ga that is related to global Paleoproterozoic UHT metamorphic events that occurred during the Columbia supercontinent assembly.

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Resumo O Complexo Lagoa Real, constituído por meta-granitóides com idade de colocação em torno de 1,7 Ga, ocorre no vale do Paramirim e engloba as rochas denominadas genericamente de Granito São Timóteo e um conjunto de granitóides milonitizados em graus variados gerados no curso de uma deformação compressional sin-metamórfica. A análise estrutural permitiu identificar duas famílias de estruturas: uma compressiva, representada por zonas de cisalhamento, bandamento composicional, foliação milonítica e dobras; e outra distensiva, marcada pela nucleação de zonas de cisalhamento normais. As estruturas deformacionais identificadas assemelham-se com as que são encontradas no sinclinal de Ituaçu, onde afloram as formações Salitre e Bebedouro do Grupo Una. Como não foi encontrada uma trama mais antiga que a primária, sugere-se que a deformação do Complexo Lagoa Real ocorreu durante o Neoproterozóico.