ASYMMETRIC HYDROGRAPHIC BASINS IN SOUTHERN ESPINHAÇO RIDGE – MINAS GERAIS STATE, BRAZIL: LITHO-STRUCTURAL AND - OR TECTONIC CONTROL / BACIAS HIDROGRÁFICAS ASSIMÉTRICAS NA SERRA DO ESPINHAÇO MERIDIONAL – MG: CONTROLE LITOESTRUTUAL E/OU TECTÔNICO

Abstract

This paper analyze the configuration of asymmetric hydrographic basins in the Southern Espinhaço Ridge (Minas Gerais state,
Brazil) through the spatial organization of fluvial archives and morphometric indexes, adopting them as instruments for
investigating the preferential migration processes of water courses under lithostructural and tectonic control. The procedures
were based on the depositional levels and sequences, as well as the Transversal Topographic Symmetry Factor (FSTT) and
Drainage Asymmetry Factor (FABD) indices. Most of the valleys have stepped and isolated depositional levels in the context
of slopes that indicate preferential lateral migration of the channels to the east under strong influence of the regional base
level, reflecting in the asymmetric hydrographic basins configuration. The indexes confirm these results, which may be related
to the dip of the Proterozoic rocks and to the regional quaternary tectonic dynamics. In the valley bottoms, in turn, the fluvial
archives are much more preserved, but their pairing on both banks does not signal the continuity of the preferential migration
of channels to the east, indicating the stabilization of base levels in the Holocene.