NOVA PROPOSTA DE COMPARTIMENTAÇÃO DO PLANALTO VULCÂNICO RIOGRANDENSE

Abstract

From the 1950’s a series of geomorphological studies searched to compartment the Brazilian relief. For the Riograndense Vulcanic Plateau, although a series of geomorphological studies made seeking its compartmentation there are still gaps mainly from studies taking in consideration the relation between lithostructure and geomorphic surfaces. Therefore, the objective of this study is to present a compartmentation of the PVRG which combines the geomorphic surface delimitation and lithostructural aspects. Secondarily the study seeks an enhancement of the previously compartmentations, showing the importance of updating geomorphological studies from news analysis tools. Thus, an identification of surfaces and delimitation of geomorphological surfaces were realized from the analyses of different georeferenced data (hypsometric, slope and roughness maps, topographic and swath profiles, lithology, faults, and lineaments) comparing and verifying its correspondence with previous classifications already existent. Thereof resulted the definition of six (6) compartments within the study area:   Planalto Central; Planalto das Missões; Planalto Sudoeste; Dissecado Rio Uruguai; Dissecado Rio Jacuí-Taquari e Dissecado Atlântico. The first three compartments refer to a roughly preserved geomorphic surface, while the other three refer to dissected compartments, where the active fluvial incision from the homonymous rivers, i.e., these areas have actively been dissected by its fluvial systems. Thus, in general, the compartmentation allowed to understand that the individualized compartments result from differential erosion of the current tributary system they belong, from the local base-levels, lithological variations within the lava flows and tectonic and structural controls.