Relações relevo-rocha-solo em borda de chapada no Triângulo Mineiro - Nova Ponte (MG)

Abstract

The plateaus of the Triângulo Mineiro constitute tablelands with eroded edge under tectonic and climatic processes, with expressive latosolization and lateritization of their surface coverings. The edges of these plateaus are dissected by drainages that depart from the flat summit towards the steep and staggered fronts, as illustrated by the watershed of Ribeirão do Brejão in Nova Ponte (MG). The area of study is located on the boundary of the Plateau of the Sedimentary Basin of Paraná, it was assumed that its evolution is the result of the formation of different geomorphic surfaces (GS). Thus, the objective of this work was to analyze the relief rock-soil relationships on the edge of the plateau of the Ribeirão do Brejão watershed, in order to investigate the evolution of the relief and the development of surface coverings. It was proposed the use of intermediate mappings for recognition and delimitation of geomorphic surfaces, with the support of anaglyphs for photointerpretation and field work. Three GS were recognized (S1, S2 and S3), which received upgrading mapping scale with details of the geomorphological characteristics, lithologies and unconsolidated sediments, and soils, grouped in a single cartographic document, named Relief-Rock-Soil Integration Map. For the identified GS, morphological descriptions were also carried out in 04 Oxisol profiles, in which deformed and undeformed samples were collected for granulometric, morphological and morphoscopic analysis of the coarse fraction, and micromorphological characterization. From the information acquired with the organization of integrated mapping, in field work, in the laboratory and in a bibliographic review, a model of relief evolution (GS) was elaborated, establishing relations with the development of the soils. In summary, the installation of geochemical processes on tertiary geomorphological surfaces, which is associated with S1, allowed the formation of lateritic covers responsible for structuring the plateaus of the study area. During the post Cretaceous climatic oscillations until the present, the formation of posterior geomorphic surfaces (S2 and S3) was verified, derived from vertical and horizontal relief evolutions.