Landforms and Landscape Evolution of the Equatorial Margin of Northeast Brazil by Jean-Pierre Peulvast & François Bétard

Author:Jean-Pierre Peulvast & François Bétard
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

Keywords

Basin inversionDenudation ratesEpeirogenyEustatismLateritePalaeogeographyPalaeolandformsStepped surfacesSoil coverUplift

4.1 Stepped Paleosurfaces and Related Soils as Indicators of Long-Term Landscape Evolution

4.1.1 The Identification of Stepped Surfaces

A series of topographic profiles transverse to the continental margin (Fig. 4.1) outlines the treads of two main topographic levels: a low plain between 0 and 300 m a.s.l., sloping gently seaward (average slope angle <0.1°), and the discontinuous elements of a high plain between 750 and 1100 m a.s.l. The latter lacks any well-defined slope, even in the Central Ceará Highlands where the high topography occurs near the coast (Fig. 4.1, profiles 8–10). Profiles east of the Senador Pompeu Shear Zone (SPSZ) (Fig. 4.1, profiles 1–4 and 5–7) highlight a deep inward extension of the embayed lower plain (‘Sertaneja’ surface) as far as the foot of the Borborema and Araripe plateaus, with residual bedrock landforms standing on the plain. To the west, except in Central Ceará Highlands (Fig. 4.1, profiles 8–10 and 11–13), the low plain also exists with a similar seaward gradient (~0.1°). The Ibiapaba plateau is characterized by the regular westward dip slope of its sedimentary strata but forms an elevated flat surface at ~1000 m a.s.l. This is similar to the other major summits of the western compartment and suggests that the plateau was once continuous between the Ibiapaba scarp and the outliers .

Fig. 4.1Topographic profiles normal to the continental margin. Source SRTM DEM

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