Morfotectônica da bacia sedimentar de Curitiba

Abstract

The morphostructural framework differentiation in the Precambrian/Eo-Paleozoic basement and Cenozoic sedimentary cover of the Metropolitan Area of Curitiba is due to extensional and transtensional neotectonic movements, with the concurrence of climatic changes. Drainage morphometric analysis indicates tectonic influence in the morphogenetic processes. Structural alignments control the sub-rectangular and sub-parallel patterns of the drainage system, the asymmetry of the second-order drainage sub-basins of the Iguacu basin river, the main local base level, and the geometry of the Cenozoic sediments, including the alluvial deposits, which present asymmetric spatial distribution and narrowing segments in areas of crossed-alignments. The main second order tributaries of the Iguacu river, like the Pequeno and Barigui rivers, present tectonically controlled channels, as indicated by the coincidence of anomalies with older structures reactivated since the Lower Tertiary, as well as scarps that may be clearly observed in digital elevation models, even not so accentuated. The higher northnorthwestern margin inclination of the Iguacu River in relation to its south-southeastern margin is a salient morphostructural characteristic related with the Upper Iguacu Fault, which deformed the Curitiba sedimentary basin and to which part of the upper Iguacu valley is adjusted. The fault was active during and after the Pleistocene, reflecting the more recent neotectonic activity, and may be recognized through the faulted colluvial-alluvial deposits and the weak seismic activities in the Serra do Mar.