Tectonic Genealogy of a Miniature Continent

Abstract

The São Francisco craton (SFC), although small in size, exhibits elements of some of the Earth principal evolutionary phases. Repeated cycles of granite-greenstone terrain formation recorded in the craton basement attest the high-heat tectonic regime that characterize the Archean Earth. Like in many other places of the world, these terrains amalgamated to form a coherent and stable continental mass in the Late Archean. In the course of the Paleoproterozoic, subduction-driven accretionary orogens, which incorporated island arcs and continental terranes, were added to the Archean continental nuclei. Typical of the Proterozoic plate tectonic regime, these events took place around the important 2.1 Ga age peak of juvenile crustal production. The collage of several blocks concurred to form the São Francisco paleocontinent, which always united to the Congo landmass, experienced a series of intraplate processes, such as rifting and associated bimodal magmatism during the following 1300 Ma-long period. Very likely, the São Francisco-Congo did not take part of the Columbia and Rodinia supercontinents. Later, in Ediacaran and Cambrian times, it was involved in the collage that resulted in the formation of the Gondwana Supercontinent. Driven by slab-pull subduction and collisional processes, typical of modern-type plate tectonics, the Rio Preto, Riacho do Pontal, Sergipano, Araçuaí-Ribeira and Brasilia belts surrounded and shaped the present configuration of the SFC. Finally, the SFC was separated from the Congo craton following the Brazil--Africa continental drift and the formation of the South Atlantic Ocean. This chapter explores the significance of rock assemblages and tectonic features exhibited by the miniature São Francisco continent in terms of Earth global processes.