Study of relief evolution of escarpment between doce/paran? basins in Minas Gerais state - southeastern Brazil by quantification Denudation rates.

Escarpamentos na forma de degraus do relevo e que limitam duas diferentes bacias hidrogr?ficas s?o comuns no leste de Minas Gerais. O presente trabalho investigou a evolu??o do que delimita as bacias hidrogr?fi cas do rio Doce (por??o leste e inferior da escarpa) com a bacia hidrogr?fica do rio Paran? (por??o oeste e superior da escarpa) via mensura??o das taxas quatern?rias de desnuda??o atrav?s do is?topo cosmog?nico 10Be. Os resultados obtidos demonstram que as taxas de desnuda??o mensuradas possuem ?ntima rela??o com a compartimenta??o do relevo, sendo baixas no planalto superior (bacia hidrogr?fica do rio Paran?), m?dias na por??o deste planalto superior que foi capturado para a bacia hidrogr?fica do rio Doce e altas na escarpa. Permitem ainda compreender que o relevo regional evolu? atrav?s de um duplo front de regress?o: o primeiro se caracteriza pelo recuo da escarpa e o segundo, localizado mais a oeste, pelas capturas fluviais. Neste contexto, comprova-se a retra??o do escarpamento para oeste, fato que faz com que a bacia hidrogr?fica do rio Doce ganhe ?rea em detrimento da bacia hidrogr?fica do rio Paran?.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 Paran? 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 (Paran? 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 Paran? catchments