Estudo da evolução da escarpa entre as bacias do Doce/Paraná em Minas Gerais através da quantificação das taxas de desnudação

Abstract

Escarpments that presents form of steps in relief and that limit two different basins are common in eastern of Minas Gerais State in Brazil. This paper investigated the evolution of the escarpment that delimits the Doce catchments (the lower and the eastern portion of the escarpment) from the Paraná catchments (the higher and the western portion of the escarpment) by measurement of the quaternary denudation rates by 10Be cosmogenic nuclide. The results demonstrate that denudation rates measured are closely related to the relief: (i) lower rates in the upper plateau (Paraná catchments); (ii) middle rates on the upper plateau that was captured into the Doce catchments and; (iii) higher rates on the escarpment. It was also possible to understand that the regional relief evolved by double front: the fi rst front is characterized by escarpment backwearing and the second, located further west, by the river captures and downwearing. In this context, it is proved the retraction of the escarpment into the west and, for consequence, the Rio Doce catchments is gaining area at the expense of the Paraná catchments.