Hillslope deposits and quaternary evolution of the Itatiaia Plateau

Abstract

Correlative deposits found on the middle and lower hillslope sectors of the plateau document the Quaternary evolution of the Itatiaia plateau. Hanging talus cones, linear concentrations of boulders, screes and two colluvium generations reflect processes related to tectonic reactivation and climatic changes. Older events, more efficient in detaching blocks and boulders from free faces - associated to a group of processes including frost action - would have been replaced by colluviation episodes. Heterometric C I colluvia with bedrock clasts and C II sequences with fewer and smaller clasts would indicate the action of processes capable only of reworking materials freed by previous erosional phases. Decrease in intensity of slope denudation favored the filling of floodplains and hydromorphic depressions with relatively fine Holocene sediments, as well as the formation of tropical altitude peatbogs.