GEOLOGIA ESTRUTURAL DO SUPERGRUPO SÃO FRANCISCO AO LONGO DA SEÇÃO REGIONAL COROMANDEL - TRÊS MARIAS CONSELHEIRO MATA, MG

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The São Francisco Supergroup is an Upper Proterozoic Sedimentary sequence deposited over the São Francisco Graton and, less frequently, over instable marginal areas, where the Brazilian fold belts developed later. Due to situation, the São Francisco Supergroup is strongly deformed by the Brazilian Cycle in the margins of the basin (São Francisco Basin), but this deformation decreases gradually toward the center. This work shows a regional section made with the purpose of setting the structural framework of the São Francisco Basin, interpreting it in a kinematic viewpoint, and establishing its relationship with the fringing units, like Espinhaço Supergroup ( at Araçuaí Fold belt) and Canastra Group ( at Brasilia Fold belt). The area so the travess was divided in three main regions: eastern a western, which deformation is related to the evolution of Araçuai and Brasilia fold belts respectively, and the very little deformed central region. In the eastern region, structures related with two phases integrated into one progressive and heterogeneous deformational event were indentified. Such event led to the development of north-south trending and westward verging fold-thrust belt. The thrusts seem to have a ramp-flat geometry, and are responsible for the emplacement of the Espinhaço Supergroup units over the São Francisco Supergroup ones. It also recognizes a conjugated pair of strikes-slip faults (WNW and NNE). This region can be subdivided into two structural domains, characterized by decreasing of the deformation intensity toward west. In the western region, the Canastra Group units (Brasilia fold belt) were subjected to a contractional phase before the sedimentation of the São Francisco Supergroup. Some evidences suggest that at least the base of the São Francisco Supergroup was deposited during a later extensional phases (De). After, all the region suffered other contractional phase, which is manifested by a NNW-N-NNE trending and eastward verging fold-thrust belt. This phase is responsible for the emplacement of Canastra Group rocks over the São Francisco Supergroup ones, for the development of inverse faults ( p.ex: João Pinheiro Fault) and for a conjugated pair of strike-slip faults. In spite of local deformational polarity inversions, due to basement highs or inverse faults, the four structural domains characterized in the region express a decreasing in the deformational intensity toward east. The non-deformed central domain, between the above-mentioned regions, did not allow any correlation between eastern and western deformational phases.

ASSUNTO(S)

trÊs marias conselheiro mata, mg supergrupo sÃo francisco geologia estrutural seÇÃo regional coromandel engenharias

ACESSO AO ARTIGO

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