Tectono-sedimentary evolution of sedimentary basins from Late Paleoproterozoic to Late Neoproterozoic in the Sao Francisco craton and Aracuai fold belt, eastern Brazil

Two first-order regional unconformities separate Proterozoic supracrustal rocks of the Sao Francisco craton and the Aracuai fold belt (eastern Brazil) into three genetic units. These constitute three superimposed first-order basin-fill cycles: the Espinhaco, Macaubas-Salinas and Bambui megasequences. The Paleo-Mesoproterozoic Espinhaco megasequence (ca. 1730-1500 Ma) was deposited in an intracratonic rift-sag basin in four stages (pre-rift, rift, transitional and flexural). Each of these stages is bounded by regional, second-order unconformities. Basin evolution was controlled primarily by tectonics, although sea-level variations were also important in the transitional and flexural stages. After a hiatus of several hundred million years, subsidence renewed during extension related to the early Neoproterozoic breakup of the supercontinent Rodinia with rift to passive-margin sedimentation in the Macaubas-Salinas Basin (ca. 950-700 Ma). Initial glaciogenic sedimentation, possibly induced by uplift related to a mantle plume, occurred in a rift setting. Subsequent a shelf/slope/deep-sea passive-margin deposits, represent opening of a northern branch of the Adamastor Ocean. Tectonic, magmatic, climatic and eustatic processes all combined to control basin evolution. The Bambui megasequence (ca. 800-650 Ma) was deposited in a foreland basin during convergent and collisional tectonics related to closure of the Brazilide Ocean and generation of the Brasilia fold belt west of the Sao Francisco paleocontinental region. The evolution of the Bambui Basin, whose fill is characterized by three transgressive-progradational, shallowing-upward sequences, was mainly controlled by tectonic processes. (C) 2001 Elsevier Science B.V. All rights reserved.