Anais da Academia Brasileira de Ciências
Print version ISSN 0001-3765
SALLUN, Alethea E.M. and SUGUIO, Kenitiro. Quaternary colluvial episodes (Upper Paraná River Hydrographic Basin, Brazil). An. Acad. Bras. Ciênc. [online]. 2010, vol.82, n.3, pp. 701-715. ISSN 0001-3765. http://dx.doi.org/10.1590/S0001-37652010000300018.
Colluvial deposits occur extensively in the Upper Paraná River Hydrographic Basin (UPRHB) in Southeastern,Southern, and Western central Brazil. These deposits were recognized as an allostratigraphic unit and related to creeping during the Quaternary. Every studied colluvial profile is homogeneous, which indicates relatively long periods of landscape stability that is sufficient for the development of a thick soil cover. The deposits were dated by luminescence and indicate periods of more intense colluvial deposition between 6 and 220 ky B.P. These events correspond approximately to the transitions between the oxygen isotope stages 2-3-4 and 5-6, suggesting that this aggradation was influenced by climatic changes. However, the most important alluviation episode was tentatively correlated with the Middle to Upper Pleniglacial of the Wisconsin glaciation. The most intensive and frequent periods of precipitation that occurred during climate transitions are probably correlated with aggradation events. The regularity of the colluvial deposits suggests continuous uplift accompanied by sediment deposition throughout the UPRHB due to neotectonic activity during the last million years.
Keywords : colluviation; alluviation; Quaternary; luminescence dating; Brazil.