Mapping superficial formations: a methodological proposal for systematic cartography of the Brazilian territory

Abstract

We present a methodological proposal for the systematic mapping of superficial formations applicable on a national scale. The importance of such a proposition stems from the fact that a large part of the Brazilian territory is located in a humid or semi-humid tropical zone, where deeply weathered and sometimes tens of meters thick lateritized regolith mantles develop. The methodological approach consists of a geological-geomorphological-pedological compartmentalization of the terrains, together with elements of morphostratigraphic analysis and of the intrinsic properties of saprolites and soils. This approach, structured in a GIS environment, was applied in two different areas in Brazil: The Federal District and the São Luis island in the state of Maranhão, where the complex geodiversity of the regolith landscape stands out in both areas. The results highlight the diversity of horizons in the regolith profile, in addition to its anisotropy. The recognition of the complexity of these superficial formations is, therefore, of great importance for a more detailed analysis of various themes, such as for civil works; susceptibility to erosion and mass movements; potential for aquifer recharge; and mineral potential. Finally, the importance of the study of superficial formations is emphasized for the improvement of geological mapping and for the multi-thematic analysis of the physical environment applied to land management.