Lamelas (Bandas Onduladas) em argissolo vermelho-amarelo como indicadores da evolução do relevo: o caso das colinas médias do platô de Bauru (SP)
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Data
2006
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Resumo
The big structural geomorphic surface situated in the west of the State of São Paulo, Brazil, and named Paulista OccidentalPlateau
is supported by fine sandstones dated from Cretaceous of Paraná Sedimentary Basin and developed under Post-Cretaceous
tropical denudation environments, compound residual and dissected plateaux. One of them, representing one of the mostly
lowered and dissected surface, named Bauru Plateau, situated on its center-southern sector is constituted by big smoothed interfluves with length slopes related to the typical Red Ferralsol (Oxisol in USA and Latosol in Brazil) in center part and
medium dissected interfluves to the boarders, with convex-concave-convex slopes related to soil succession interpreted as
lateral pedological transformation system, constituted by Red and Red Yellow Ferralsol on the tops, Red Yellow Ferralsol with
elevated textural gradient (Ultisol in USA and Argisol in Brazil) dominant in middle slopes, and Gleisol on the foothills and
alluvial plain. This Red Yellow Ferralsol with eluvial horizon (E) frequently presenting numerous suspended and undulated
fine yellowish sandy clayed lamellae, or red, thick, clayed and connected to the subjacent hydromorphic B argilic horizon (Btg)
by a little peduncle projected in semi-arc to the foothill, is related to controversies about its origin. One representative soil
profile from a typical toposequence was selected in order to illustrate the lamellae genesis and its relationships with the
hydromorphic B horizon and the hillslope evolution. Macromophological and micromorphological study and physical -
hydrological measures (texture, porosity and saturated hydraulic conductivity) over collected soil samples on length pit, was
done. The results emphasizes the formation of lamellae and Btg horizon by e-illuvial mechanisms related to the hydromorphic
action in the E-Btg transition and elluviation in E horizons associated to a suspended water level; a transitory soil features in
pedological development of medium slope by consequence of internal lateral loss of clay and residual accumulation of sandy
in superficial horizon conducting to a topographic deepening and potentialized by superficial concentrated water flows in
favors to dissection. The origin of these processes is attributed to successive hydraulic adjustments of the interfluves
inducted by depression of the base level under humid post-cretaceous climate. The lamella features representing the notables
preserved features of the soil geomorphology development witch is functional until present.
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Relação pedogênese x morfogênese, Pedogenesis and morphogenesis, Platô de Bauru, Colinas médias, Argissolo Vermelho-Amarelo, Hidromorfia suspensa, Lamelas (bandas onduladas), E-iluviação, Plateaux of Bauru, E-illuvial processes, Medium dissected interfluves, Suspended water level, Red Yellow Ferralsol, Lamellae
Citação
SANTOS, Leonardo José Cordeiro; CASTRO, Selma Simões de. Lamelas (Bandas Onduladas) em argissolo vermelho-amarelo como indicadores da evolução do relevo: o caso das colinas médias do platô de Bauru (SP). Revista Brasileira de Geomorfologia, Curitiba, ano 7, n. 1, p. 43-64, jan./jun. 2006.