More than a simple monograph, the authors present a comprehensive geomorphic overview of a large tropical region where they show how deciphering the long-term landform evolution helps understanding the present set of landscapes and morphodynamic environments. The Equatorial margin of the Brazilian "Nordeste" displays stratigraphic landmarks whose interpretation reveals the age and nature of landforms, leading to a reconstruction of the geomorphic history by the means of combined morphostratigraphic and morphopedological approaches. Beyond the role of differential erosion related to moderate post-oceanic opening uplift, the plain and upland landscape reflects a juxtaposition of landform and soil generations related to a shallow basin inversion, the last stages of which occurred in semi-arid conditions since the Oligocene. These results throw light on old debates on models of long-term landform development in platform areas, and also help evaluating recent models of denudation and burial based on thermochronological methods.

Auteur
Jean-Pierre PEULVAST is Professor Emeritus of Geomorphology at the University of Paris-Sorbonne. He also teaches in the Master Degree and Doctorate program at the Federal University of Ceará (UFC), Fortaleza, Brazil. His principal field of interest is structural geomorphology, but he is also involved in programs of geoarcheology (Egypt) and in studies on natural hazards and risks (Northeast Brazil). He mainly works on passive margins around the Atlantic Ocean (Scandinavia, Greenland, Canada, Brazil, Argentina), but also on various regions of France, Mediterranean Europe and Central Asia, and has participated in programs on the geomorphology of Mars.

François BÉTARD is Associate Professor in Physical Geography and Environmental Science at Paris-Diderot University, and a member of the research team CNRS UMR 8586 PRODIG. His main research interests lie in the fields of geomorphology, soil science and rock weathering, with a special focus on tropical and paleotropical environments. Involved in the study of paleolandforms and related paleoweatherings at various geological timescales, he worked extensively in South America (Northeast Brazil and Southern Patagonia), but also in France (Armorican Massif, Paris and Aquitaine Basins). Ongoing studies include applied research in the fields of conservation and valorization of geological and geomorphological heritage into protected areas (natural parks and reserves, geoparks).

Contenu

1 Introduction.- 2 Geological setting: the Borborema Province.- 3 Morphostructural patterns.- 4 Stepped surfaces, palaeolandforms and morphostratigraphy.- 5 Late Cenozoic evolution of landforms.-
6 Conclusion and perspectives.