Análise geomorfopedológica em borda de chapada do oeste mineiro: Estrela do Sul (MG)

Abstract

The geomorphopedological contributes to the assessment of relief evolution and spatial distribution and formation of pedological couverture. The plateau edges of Dolearina rural district in Estrela do Sul, mesoregion of Triângulo Mineiro e Alto Paranaíba (MG), presents geomorphopedological contexts that related to many different morfoestructural units limitated for escarpment fronts supported by laterites. Are also found different lithotypes which control forms such as tabular plateaus, dissected plateaus, residual reliefs, colluvial slopes, resulting in the soils different class which may contain stone lines in the profile. It is suggested that this erosive escarpment has regressed and is still receding toward the latosolized Tabular Plateaus, leaving features of residual reliefs positioned in front of erosive escarpment. Therefore, this work has the aim to collaborate with investigations on the evolution of the relief and the development of the soils on the edge of the plateau positioned in Dolearina, through the geomorphopedological approach. For this, the investigation applied the first two levels of methodological treatment presented by Castro and Salomão (2000). At the first level, cartographic procedures were adopted to the geomorphopedological compartmentation. On the second level, field work was carried out with longitudinal sections/transects that intersect the geomorphopedological units, in addition to laboratory analyzes of collected samples. Five Geomorphopedological Units were reconized: Wet Redoximorphic (I); Flattened Latosolized Tabular (II); Laterized Escarpment on Structural Levels (III); Pedogeneized Regolithic Dissected (IV); and, Rocky Residual Saprolitc (V). It was observed that the stratigraphy in the escarpment front of Geomorphopedological Unit (III) presents contact of sedimentary rocks with crystalline basement already in its middle third. The Geomorphopedological Unit (V), found in great quantity, is characterized by ruiniform features constituted by sandstone, of great similarity to the sandstones that also support the escarpment positioned in Unit III, which shows the retreat of the front. In the Pedogenized Regolithic Dissected Unit (IV) stone lines derived from autochthonous materials are found. These are associated with the remobilization of laterites fragments from the higher topography of the steep front and from hills with convex tops, which share the same altimetric leveling, a fact that also corroborates as evidenced by the retreat of the front. The work also brought contributions to an evolutionary residual relief model, discussing possible cuestiform context, Glint and Peripheral Depression on the edge of the Basin, in addition to the geochemical evolution of alteration profiles and associated soils.