Geologia do Grupo Paranoá na porção externa da Faixa Brasília

TLDR: The Paranoa Group represents a psamo-pelitic-carbonated succession deposited in shelf conditions as discussed by the authors and is considered to have been processed in the Mesoproterozoic (1,542 to 1,042 Ma).

Abstract: The Paranoa Group represents a psamo-pelitic-carbonated succession deposited in shelf conditions. The stratigraphy of this important lithostratigraphic sequence of the Brasilia Fold Belt was originally proposed by letter-code designation that includes 11 units with the following stratigraphic stacking: SM, R1, Q1, R2, Q2, S, A, R3, Q3, R4 and PC. The present paper formalizes these units and proposes the following denomination to the formations, named from base to top: Ribeirao Sao Miguel, Corrego Cordovil, Serra da Boa Vista, Serra Almecegas, Serra do Parana, Ribeirao Picarrao, Ribeirao do Torto, Serra da Meia Noite, Ribeirao Contagem, Corrego do Sansao and Corrego do Barreiro. The deposition of the Paranoa 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 Arai Group and under slates and carbonates of the Bambui 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 Paranoa Group is mainly controlled by the Parana and Rio Maranhao thrust systems and by the Ribeirao Sao Miguel shear belt.