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Tectônica extensional no cinturão Paraíba do Sul no noroeste do Rio de Janeiro: análise estrutural na seção Itaperuna (RJ) – Muriaé (MG)

2007; Sociedade Brasileira de Geologia; Volume: 37; Issue: 3 Linguagem: Inglês

10.25249/0375-7536.2007373625636

2177-4382

Tiago da Rocha Karniol, Rômulo Machado, Letícia Constantino Vicente,

Geochemistry and Geologic Mapping

This paper describes extensional and contrational structures along the Itaperuna (RJ) - Muriaé (MG) section, northwestern part of Rio de Janeiro State. Three structural domains were described where more deformed portions are characterized by the presence of steeply dipping shear zones with associated mylonitic rocks, and less deformed portions show granulites and charnockites with well-preserved structures and textures. In three structural domains, the foliation runs towards NNE-SSW with sub-vertical and intermediate dip. Stretching lineation is mainly subhorizontal and at some outcrops form downdip structures. Kinematic indicators (S-C and S-C-C’ foliations, asymmetric structures, σ-porphyroclasts, shear-bands and boudins) suggest top-to-SSW shearing and dextral strike-slip component, sub-parallel and oblique to the orogenic trend for the contractional segments and top-to-ESE shearing for the extensional segments. The structural evolution of the area is considered as a result of a regional dextral and partially confined transpression, where strain path partitioning was related to external boundary conditions on the south portion of the Sanfranciscana plate. The extensional event presented in this paper is considered older than the event of the orogenic collapse (520 to 480 Ma) proposed for the Araçuaí orogen and central portion of the Paraíba do Sul/Ribeira belt.