geologia

Revista Brasileira de Geociências

22(4):481-486, dezembro de 1992

O CRÁTON BRASILIANO DO SÃO FRANCISCO - UMA REVISÃO

ROLAND R. TROMPETTE*, ALEXANDRE UHLEIN**,
MARCOS E. SILVA*** c IVO KARMANN***

ABSTRACT THE BRAZILIAN SÃ O FRANCISCO CRÁ TON - A REVIEW. The Brazilian Paramirim belt divides the São Francisco Craton. At to the west and southwest occurs the São Francisco Craton (sensu strictu), and to the East is present flic Salvador Craton,separated from the Congo-Zaire Craton by the opening of the Atlantic Ocean during Early Mesozoic time. The Archean-Early Proterozoic basement of the Paramirim belt was intruded by subalkaline granites approximately 1,700 Ma old. The Espinhaço Supergroup is die most important unit of the
Paramirim belt It's made up of detritic metasediments (quartzites, metaconglomerates, phyllites) with acid metamagmatíc rocks (rhyolites-rhyodacites) in the lower part. The Espinhaço Supergroup was deposited hi a continental rift during the interval 1,700 to 1,100 Ma. The Espinhaço Supergroup deformation is roughly dated at 600 Ma
(Brazilian Tectonic Cycle). R is characterized by major ductile north-south low-angle shear zones and assymmetric folds with westward vergence. A stretching or/and mineral lineation, transverse to the belt, indicates westward transport of materials. These ductile shear zones continue to the south, affecting the external units of de Aracuaf fold belt and older
(Early Proterozoic) units of the Quadrilátero Ferrifero (MG).
Keywords: São Francisco Craton, Brazilian Paramirim belt, Bahia, Brasil.
RESUMO A faixa ou província brasiliana do Paramirim divide o Craton do São Francisco em dois. A oeste e sudoeste ocorre o Craton de São Francisco (sensu stricíu) e a teste, o Craton de Salvador, separado do Craton do CongoZaire pela abertura do Oceano Atlântico Sul durante o Mesozóico. A infra-estrutura da Faixa do Paramirim, arqueana e proterozóica inferior, está intrudida por granitóides subalcalinos