THE STRATIGRAPHY OF BRAZIL: A CONTINENTAL-SCALE TASK

Brazil is one of the largest countries in the world and has extensive Precambrian cratons and Phanerozoic basins located in the continent and along the Atlantic Ocean platform. The Amazon, São Francisco and La Plata cratons have been intensily studied over several decades by the Geological Survey of Brazil (CPRM). The oil-producing sedimentary basins along the Atlantic coast have been studied by Petrobras for 50 years. Several universities have investigated both the cratons and the basins. This extensive data base is integrated and summarized by the Stratigraphy Commission of the Brazilian Geological Society, and made available to the international community. The authors of this abstract are members of the commission. Several stratigraphic problems have been solved in the cratons, such as the significance of the extensive granitic-gneissic terrains in the Amazon craton. But many problems remain, such as the subdivision of "complexes" and the necessity to use "suite" for the stratigraphic subdivision of granitic terrains. How to correlated well mapped units with poorly known terrains? The stratigraphy of the Phanerozoic basins is well understood in many aspects, but there is a need to define more precisely several stratigraphic units. We welcome the work done by the Stratigraphy Sub-Commission of IUGS, but we will adapt the Guide to Brazilian stratigraphic needs and thus contribute to the international evaluation of the geological relationships in cratons and basins. Brazil seeks a seat in the international bodies (IUGS) related to stratigraphy, in order to make available to the international community the extensive work done in the country's geology over the last 50 years. We wish thus to fill a gap in the international knowledge of a large portion of the planet's crust and to advance the international understanding of the many problems related to the stratigraphy of the world.