Cabeceiras de drenagem no planalto das araucárias, bacia hidrográfica do rio Guassupi-RS: distribuição espacial das depressões fechadas, controle estrutural e evolução geomorfológica

Abstract

The Planalto das Araucária in Rio Grande do Sul is the stage for the development of a series of geomorphological processes that result in the formation of an expressive number of Closed Depressions and Headwaters Drainage constituting a natural element characteristic of the landscape of the region. Therefore, the problem of this research consisted in questioning the relationship between the Headwaters Drainage in the Guassupi River basin and the genesis and evolution of the Closed Depressions in dividers, as well as to investigate the role of these landforms in the evolution of the local relief. The objective of the research was to understand the morphogenetic processes generators of Closed Depressions and Headwaters Drainage and to verify the relation of these landforms to the evolution of the relief. The methodological procedures consisted in searching the relationship between the different variables involved in the genesis and evolution of landforms, among them the morphological variables, lithological, structural, topographic, and related to the weathering profile. The landforms were framed in four sets according to their morphological properties and evolutionary sequence: Closed Depressions; Divider Headwater Drainages; Shallow Concavities; and Depression in the Valley Bottom. It was found that the landforms develop in the crossings between groups of lineaments direction SE and NE, and associated with the portions of the volcanic spills where the Amigdalar Brechoide Zone occurs. The hypothetical model of evolution of the relief for the Guassupi river basin, shows that the compartment Fundo de Vale Dissecado moves toward the Topo do Planalto as a consequence of the geomorphological evolution of the landforms researched.