Laterite preservation and soil distribution in the Araripe-Campos Sales area, Northeastern Brazil: consequences of uplift, erosion and climatic change - Archive ouverte HAL Accéder directement au contenu
Poster De Conférence Année : 2005

Laterite preservation and soil distribution in the Araripe-Campos Sales area, Northeastern Brazil: consequences of uplift, erosion and climatic change

Résumé

The Araripe-Campos Sales area in semi-arid Brazilian “Nordeste” is locally capped by lateritic plateau remnants that have never been precisely mapped. All these laterites are preserved on a high exhumed pre-cenomanian paleosurface (600-650 m a.s.l.) entirely developed on a gneissic or granitic bedrock. On the top of the Chapada do Araripe (800-900 m a.s.l.), the Cenomanian Exu sandstones have only allowed the formation of non-indurated ferrallitic soils. Another class of soils (“fersiallitic” soils, typified by rubefaction and significant occurrence of 2/1 clays) is principally developed on a lower topographic level (300-400 m a.s.l.) connected to the low “Sertaneja” surface shaped into the crystalline basement. If lithology appears as a discriminating factor to explain some aspects of the laterite and soil distribution (between sedimentary cover and crystalline rocks), it is insufficient to explain the differences observed within the crystalline basement in a region of homogenous semi-arid climate. So it is necessary to develop a model that accounts adequately for these observations. This can be achieved by considering a morphotectonic model that combines the effects of tectonics, erosion and climatic change. The uplift history, which also controls patterns and rates of regolith stripping, seems to be a key to understanding the regional geography of weathering and soils in a context of increased aridity during the Cenozoic.
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Dates et versions

hal-01082535 , version 1 (13-11-2014)

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  • HAL Id : hal-01082535 , version 1

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Francois Betard, Jean-Pierre Peulvast, Vanda Claudino Sales. Laterite preservation and soil distribution in the Araripe-Campos Sales area, Northeastern Brazil: consequences of uplift, erosion and climatic change. 6th International Conference on Geomorphology, Sep 2005, Saragosse, Spain. ⟨hal-01082535⟩
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