Sedimentary provenance and role of tectonic inheritance on the control of the Macaúbas group, eastern margin of São Francisco Craton (SE Brazil)

Abstract

The Neoproterozoic Macaúbas Group represents the precursor basin system of the Araçuaí–West Congo orogen, located in the southern margin of São Francisco Craton, and records a Tonian volcano-sedimentary succession, at the base, overlain by a Cryogenian sequence related to the Neoproterozoic global glacial event. Detailed stratigraphic surveys along the Tonian units allowed the identification of two lithofacies associations related to alluvial fan and braided river environments, while the three Cryogenian lithofacies associations indicate a glaciomarine environment associated with extensive tectonics that has evolved into a marine environment. The results show that the age spectra of the Tonian and Cryogenian units are similar, differing mainly for an increased peak in the Cryogenian sample in ca. 1.0 Ga, where the primary source is probably related to those magmatic rocks associated with the Stenian-Tonian extensional breakup of the São Francisco-Congo paleocontinent. The KS-Test shows that not all the Tonian samples are similar to each other, as in all the Cryogenian samples. The detailed stratigraphic and structural surveys associated with the geochronological U–Pb data allow us to interpret that the Tonian and the basal Cryogenian sequences were deposited in two episodes of an active intracontinental tectonic context related to fault reactivations along the WNW-ESE Pirapora aulacogen structures in superimposed basin-cycles, the middle-to late-Cryogenian sequences extrapolated the WNW-ESE boundaries while the basin local depocenter and its surroundings expanded to a large depocenter during the basin evolution.