Open AccessLate Q uaternary colluvial deposits in the B ocaina P lateau, southeastern B razil highlands: age and palaeoenvironmental consequences
Author(s) -
Hiruma Silvio Takashi,
ModenesiGauttieri May Christine,
Riccomini Claudio
Publication year - 2013
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/j.1502-3885.2012.00272.x
Subject(s) - colluvium , geology , quaternary , pedogenesis , plateau (mathematics) , paleosol , radiocarbon dating , geochemistry , sedimentary depositional environment , geomorphology , paleontology , soil water , structural basin , soil science , alluvium , mathematical analysis , mathematics , loess
Despite the generalized occurrence of colluvial deposits in the humid tropical areas of southeastern B razil, regional correlation is difficult because the deposits are discontinuous, and chronological data are very scarce and scattered. For the first time, colluvial deposits in the B ocaina P lateau are described, including 18 radiocarbon ages from 12 profiles. The plateau is located on the eastern flank of the C ontinental R ift of S outheastern B razil and is the highest part of the S erra do M ar, with elevations up to 2000 m above sea level. Because the B ocaina P lateau is part of the summit surfaces of southeastern B razil, it was subjected to specific climatic conditions during the Quaternary. Colluvial deposits on the lower hillslopes and edges of amphitheatres can show complex sequences with up to three intercalated dark humic horizons, corresponding to L ate P leistocene and H olocene phases of morphodynamic activity and pedogenesis. Ages of palaeosols vary from 650±50 a BP to 36 880±980 a BP . Landforms and colluvia on the B ocaina P lateau are very similar to those found on the opposite flank of the continental rift, on the C ampos do J ordão P lateau. Ages of buried soils point to similar soil formation and colluviation episodes in the two plateaus. As in C ampos do J ordão, the succession of erosive, depositional and pedogenetic processes on the altos campos hillslopes is probably related to late Quaternary climate changes.