Geological Background: A Tectonic Panorama of Brazil

The landforms and landscapes discussed in this book developed in a variety of terrains, which together express the diversity of the geological background of the Brazilian territory. Located essentially in the old and relatively stable nucleus of the South American plate (known as the South American platform), Brazil comprises seven major categories of tectonic units, which are as follows: cratons, Brasiliano orogenic systems, Palaeozoic sag basins, equatorial margin basins, eastern margin basins, sub-Andean basins, and Tertiary rifts. The cratons together with the Brasiliano orogenic systems form the Precambrian basement of the continent. Exposures of these units comprise three distinct morphotectonic domains, namely the Guianas, central Brazil, and Atlantic shields. The four cratons delimited in Brazil represent stable lithospheric pieces that escaped the effects of the collisional processes responsible for the amalgamation of Gondwanaland, the large landmass from which South America and other southern continents derived. The Brasiliano orogenic systems form a network of collisional belts between the cratons, which were stitched together by the end of the Neoproterozoic Era. The Phanerozoic basins of Brazil record the long residence of South America in Gondwana and Pangaea, the breakup of the supercontinent during the Early Cretaceous, and subsequent processes. Large Palaeozoic sags cover a substantial portion of the Brazilian interior, whereas the eastern and equatorial margins host Cretaceous to Recent sedimentary successions. The tectonic units distinguished in the Brazilian territory have distinct expressions in the large-scale topographic relief. The lowlands are underlain by the cratons and covered by Palaeozoic sag basins. The highlands correspond to the Neoproterozoic orogenic systems, on which Phanerozoic structures such as arches, plateaus, and uplifts are superimposed.