Altera??o superficial e pedogeomorfologia no sul do Complexo Ba??o ? Quadril?tero Ferr?fero (MG).

Alguns aspectos dos processos de altera??o superficial e seus reflexos na pedogeomorfologia Quatern?ria na sub-bacia do alto Ribeir?o Maracuj?, no Complexo Ba??o, Quadril?tero Ferr?fero, MG, s?o aqui caracterizados. S?o investigados caracteres relativos ? din?mica evolutiva de tr?s vertentes (toposseq??ncias 1, 2 e 3), situadas sobre gnaisses, mas com graus de erodibilidade diferenciados. Nos segmentos de alta vertente das toposseq??ncias 1 e 2, os perfis de solos s?o pouco desenvolvidos e aut?ctones. Na toposseq??ncia 3, no mesmo segmento, ocorre um Latossolo com fei??es de aloctonia. Nos segmentos de meia vertente, das tr?s toposseq??ncias ocorrem perfis latoss?licos espessos, desenvolvidos a partir de sedimentos coluviais provindos da alta vertente. Nos segmentos de baixa vertente, h? ruptura nos processos de transporte e deposi??o dos sedimentos, sendo o perfil de solo da toposseq??ncia 2 um Latossolo C?mbico aut?ctone e, nas toposseq??ncias 1 e 3, perfis desenvolvidos a partir de materiais al?vio-coluviais depositados sobre o saprolito gn?issico. Apesar de a din?mica evolutiva das tr?s vertentes corroborar os modelos geomorfol?gicos tropicais at? o segmento de meia vertente, a jusante, a ruptura do coluvionamento na baixa vertente evidencia um recente desequil?brio morfodin?mico. Al?m disso, as evid?ncias micromorfol?gicas e mineral?gicas n?o sinalizam correla??o com susceptibilidade erosiva diferenciada verificada na ?rea.This study defines some aspects of superficial alteration processes and their reflexes on the Quaternary pedogeomorphology in the sub-basin of the upper Maracuj? River, in the Complexo Ba??o, ferriferous zone, State of Minas Gerais, Brazil. Characteristics related to the dynamic evolution of three gneiss-underlayered toposequences (1, 2, and 3) at different erosion stages were investigated. In the top slope segments of the toposequences 1 and 2 the soil profiles are little developed and present an in situ evolution. In toposequence 3, the soil profile of the same top slope segment is a well developed Oxisol with allochthonous features. Similarly, in the mid slope segments of the three toposequences, the soil profiles are thick, Latosolic, originated from the colluvial sediments that descended from the top slope. However, there is a rupture in the sediment transport and deposition process in the low slope segments. The soil profile of toposequence 2 is an autochthonous Cambic Oxisol, while the toposequences 1 and 3 profiles were developed from alluvial - colluvial materials deposited on the gneiss saprolite basement. Despite the fact that dynamic evolution of the top and mid slope segments of the three toposequences corroborate the tropical geomorphological models up to the mid slope segment, the rupture in colluvial deposition to the lower slope segments suggests a recent morphodynamic imbalance. Besides, the micromorphological and mineralogical features do not present any correlation with the differentiated erosive susceptibility verified in the area