The origin and evolution of the South American Platform

The South American Platform is defined as the stable continental portion of the South American plate not affected by the Phanerozoic - Caribbean and Andean - orogenic zones. It is surrounded by these orogenic zones and extends to the marginal Atlantic coast. The basement of the platform consists of Archean and Proterozoic continental crusts arranged during three main sets of orogenic events: (1) Trans-Amazonian (Paleoproterozoic), (2) Late Mesoproterozoic and (3) Brasiliano/Pan African. The latter resulted in the consolidation of the youngest mobile belts of the platform basement. It is, by far, the main phenomenon responsible for the overall pattern of tectonic components (cratonic nuclei and fold belts) and the formation of the general structural framework at the time when the platform was a portion of the Gondwana supercontinent. During the Phanerozoic Eon, different cover stages were developed through six main sedimentary cratonic sequences, of which the last one is exclusive to the South American continent. The final individualization stages and their respective post-Paleozoic sequences were accompanied by a series of specific intracratonic processes, both tectonic (rift basins, overprint of new structural styles in previous basins) and magmatic (basaltic and alkaline). The activation processes have generally been attributed to the opening of the Atlantic Ocean on the east and the Andean orogeneses on the north and west. Nevertheless, a minor part of these events may have been caused by sublithospheric actions (mantle-activated processes) beneath the interior of the platform. (C) 2000 Elsevier Science B.V. All rights reserved.