Tectonic aspects at the eastern border of Três Córregos Granitic Complex emplacement, Cerro Azul (PR)

Abstract

During the neoproterozoic collisions related to the ending of Brazilian Cycle, several magmatic events took place in the southern Ribeira Belt, producing large granitic intrusions held in different tectonic environments. The Três Córregos granitic suit is one of the most important magmatic records owing to its expressive and tectonic significance, with several plutons developed in a complex evolution and polyphasic tectonic conditions involving variables during their emplacements. The structural pattern and petrotectonic records of the border of granites and theirs country rocks suggests distinct stages to the emplacement of different facies in the eastern border, were are recognize São Sebastião and Arrieiros – Cerro Azul granitic units (s.l facies), intrude in metavolcano-sedimentary rocks of Agua Clara formation. Those country rocks are associated to mesoproterozoic basins, deformed and metamorphosed during the neoproterozoic history, with early thrust belts stages and to transcurrent shear zones. For the study of the evolution of the Três Córregos granitic suit and related wall rocks in an integrated approach, this research was developed applying structural and petrotectonic analysis together with geophysical data interpretation. The early stages of Apiaí terrane deformation were characterized by a thrust tectonic event, which one developed S₁ and S₂ foliations in the metavolcanossedimentary rocks of Água Clara formation. The eastern portion of Três Córregos Granitic Suit shows a low dip angle magmatic foliation, even in the regions near by the limits with wall rocks, suggesting an active tectonics condition during the emplacement. The metamorphic records also support this hypothesis, having been generated under pressure and temperature conditions compatible with the overlap of the emplacement processes by the development thrust shear zones.