Mega-geomorphology and morphostructure of the Borborema Plateau

Abstract

The morphostructural approach to landforms can be defined in several scales, taking into account different aspects of morphogenesis. In this regard, this work aims to emphasize the role of endogenous components in the morphogenesis of the main landform of Brazils Northeastern bulge, the Borborema Plateau. The morphostructural approach was adopted in this study seeking to reconstruct the influence of endogenous mechanisms on the regional hierarchy of landform units. Based on the specialized literature, and on the cross-analysis, in digital format, of regional geological map, digital elevation models and topographic transects, it was possible to develop a conceptual model for the morphostructural subdivision of the Borborema Plateau into eight distinct units. Following the mapping of the Borborema Plateau units, the role of structural and lithological controls was highlighted based on topographic transects, which enabled a better understanding of each unit and their defining elements. Therefore, it was observed that the Borborema Plateau comprises the set of highlands continuously distributed along the eastern seaboard of Northeastern Brazil, northern São Francisco river, above the 200 meters contour line, with boundaries marked by a sequence of topographic escarpments, whose epeirogenic origin is related to the breakup of Gondwana super-continent, as well as to the within-plate magmatism throughout the Cenozoic. From the methodological standpoint, the identification of three hierarchical levels of morphostructural units, namely, Borborema province macrodome including its Phanerozoic basins, the Borborema Plateau itself and their units, calls into question the validity of some classical models of landform taxonomy, which assign only one category to the above-mentioned morphostructural units.