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Geologia do Grupo Paranoá na porção externa da Faixa Brasília

2013; Sociedade Brasileira de Geologia; Volume: 43; Issue: 3 Linguagem: Inglês

10.5327/z2317-48892013000300004

2317-4889

José Elói Guimarães Campos, Marcel Auguste Dardenne, Flávio Henrique Freitas-Silva, Marco Antônio Caçador Martins-Ferreira,

Geological formations and processes

The Paranoá Group represents a psamo-pelitic-carbonated succession deposited in shelf conditions.The stratigraphy of this important lithostratigraphic sequence of the Brasília Fold Belt was originally proposed by letter-code designation that includes 11 units with the following stratigraphic stacking: SM, R 1 , Q 1 , R 2 , Q 2 , S, A, R 3 , Q 3 , R 4 and PC.The present paper formalizes these units and proposes the following denomination to the formations, named from base to top: Ribeirão São Miguel, Córrego Cordovil, Serra da Boa Vista, Serra Almécegas, Serra do Paranã, Ribeirão Piçarrão, Ribeirão do Torto, Serra da Meia Noite, Ribeirão Contagem, Córrego do Sansão and Córrego do Barreiro.The deposition of the Paranoá Group is considered to have been processed in the Mesoproterozoic (1,542 to 1,042 Ma).This age interpretation is supported by the stratigraphic position (as it occurs over the post-rift phase sediments of the Araí Group and under slates and carbonates of the Bambuí Group), by the presence of conical stromatolite (conophyton) and by isotopic data.The sedimentation was controlled by transgressive-regressive cycles, including grading and traction processes, debris flows, tides, waves, storms and basin bottom paleogeography.The sediments were affected by low-grade metamorphism and the deformation resulted in the formation of monoclines, different styles of folds (chevrons, in box and cylindrical ones) and folding interference resulting in domes and structural basins.The regional deformation of the Paranoá Group is mainly controlled by the Paranã and Rio Maranhão thrust systems and by the Ribeirão São Miguel shear belt.