Navegando por Assunto "Dobras kink bands"

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Deformação das rochas siliciclásticas paleoproterozoicas do Grupo Araí como exemplo das reativações de falhas do embasamento, Serra do Tepequém, Roraima, norte do Brasil
(2012-12) FERNANDES FILHO, Lucindo Antunes; PINHEIRO, Roberto Vizeu Lima; TRUCKENBRODT, Werner Hermann Walter; NOGUEIRA, Afonso César Rodrigues
Serra do Tepequém region comprises paleoproterozoic siliciclastic rocks from Araí and Suapi Groups, which are part of Roraima Super-group. Field data indicate that bedding is dipping towards SE and NW in different domains limited by NE-SW sinistral oblique faults with both normal and also reverse displacements. The structural setting is formed by regional scale forced folds represented by kilometre scale kink bands and chevron folds. The proposed framework is compatible with upper-to-middle crustal level. The studied faults were controlled by reactivation of early ductile basement fabric. These findings differ from previous regional models, based on folding under ductile conditions related to colisional tectonics. Results evidence the importance of Guiana Shield early basement structures in controlling the geometry of the brittle structures, which were seen on the cover rocks of Serra do Tepequém.