Evolução e condicionantes geomorfológicos da superfície sertaneja setentrional e suas implicações para as paisagens vertissólicas (Nordeste do Brasil).

Abstract

The Brazilian Northeast exhibits high pedodiversity, resulting from sculpting processes and the region's lithological diversity. However, these landscape elements are often studied in isolation, making it difficult to achieve an integrated understanding of soil and landscape evolution. This study investigates the vertisol landscapes of the Superfície Sertaneja Setentrional, a semi-arid geomorphological unit in the Brazilian Northeast, using a multiscale approach to examine how the flattened landscape influenced the formation and distribution of Vertisols through the interaction of lithological, geomorphological, and pedological factors. To achieve this, we selected three hydrographic basins (Rio do Peixe, Banabuiú, and Jaguaribe) encompassing distinct lithological and topographic contexts. The methodological framework included regional cartographic analysis, extracting topographic metrics (ksn, knickpoints, local relief, swath, and longitudinal profiles), luminescence dating (LOE), and pedological analyses. At the regional scale, we found that the distribution of Vertisols is associated with the long-term evolution of the Borborema Province, influenced by Cretaceous tectonic processes that led to rift opening, resulting in the deposition of intracratonic basins. These processes also played a role in shaping lithological resistance in crystalline terrains, where Cenozoic morphogenesis contributed to the differentiation of distinct landforms and surfaces. At the hydrographic basin scale, we identified knickpoint patterns marked by differential erosion, which regulate the persistence of vertisol landscapes within a transitional setting. An exception is observed in the Rio do Peixe Basin, where river capture removed part of the sedimentary materials, establishing a new base level, possibly in a more recent period. Our findings indicate that Vertisol distribution is associated with areas of low erosive potential and low altitudinal amplitude. LOE dating of the profiles revealed the Holocene ages, suggesting that vertic processes predominated during this period. Additionally, micromorphological analyses and weathering indices indicate active pedogenesis influenced by allochthonous materials. These results highlight the importance of understanding the interplay between morphogenesis and pedogenesis in the Brazilian semi-arid region, contributing to a deeper comprehension of the complex interactions between soils and landforms in landscape evolution