Sedimentary petrology and detrital zircon U–Pb and Lu–Hf constraints of Mesoproterozoic intracratonic sequences in the Espinhaço Supergroup: Implications for the Archean and Proterozoic evolution of the São Francisco Craton

Abstract

The Espinhaço Basin is one of the largest Precambrian intracratonic basins in the Brazilian Shield, and it comprises three tectonostratigraphic megasequences, i.e., the Lower, Middle, and Upper Espinhaço sequences, deposited from 1.8 to 1.68Ga, 1.6 to 1.38Ga, and 1.2 to 0.9Ga, respectively. Each megasequence contain detrital materials derived from the denudation of basement and/or cover units and can be used to decipher the paleogeographic evolution of the São Francisco Craton, together with the vertical and lateral stratigraphic architecture. Sandstone compositions and detrital zircon U–Pb ages and Lu–Hf isotopes from the Middle and Upper Espinhaço sequences were investigated, in conjunction with stratigraphic data, to reveal distinct provenance patterns. Sandstones in the lower units of the Middle Espinhaço sequence were recycled from sedimentary sources and were found to contain Paleoproterozoic zircon grains, either juvenile or evolved from Mesoarchean or Neoarchean crustal sources. This pattern is succeeded by sandstones derived from recycled sedimentary sources that contain juvenile and remelted zircon grains formed in the Paleoarchean, Neoarchean, and Paleoproterozoic eras. The overlying units of the Middle and Upper Espinhaço sequences include significant inputs from Statherian and Calymmian zircon grains, in addition to the Archean and Paleoproterozoic grains. This points to both a stratigraphic inversion of the source area due to the denudation of Archean basement terrain in the lower sections and a change of provenance with the input of Statherian and Calymmian zircons in the upper sections. In addition, the ages and Hf isotopic compositions of zircon grains older than 1.8Ga match the evolution of the continental crust within the São Francisco Craton. A possible chronocorrelation between the late Paleoproterozoic to Mesoproterozoic cratonic sequences in the Congo–São Francisco Craton and those sequences preserved within the Fennoscandian and Indian shields as well as in the North American, West Australian, and North China Cratons implies similar evolutions for these regions after ca. 1.8Ga. Such a similarity is probably related to the evolution of the Columbia supercontinent and its transition to the Rodinia supercontinent.