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A bacia de antepaís paleoproterozóica Sabará, Quadrilátero Ferrífero, Minas Gerais.

2002; Sociedade Brasileira de Geologia; Volume: 32; Issue: 1 Linguagem: Inglês

10.5327/rbg.v32i1.958

2317-4889

Luciana Andrade Reis, Marcelo A. Martins-Neto, Newton Souza Gomes, Issamu Endo, Hanna Jordt-Evangelista,

Geological and Geochemical Analysis

The Sabara Group is a 3 - 3.5 km thick sequence composed of schists, meta-sandstones, meta-siltites, meta-conglomerates, meta-diamictites, meta-rhythmites and phyllites, whose protoliths are greywackes, sandstones, siltites, conglomerates, diamictites, rhythmites and pelites. The rocks of the Sabara Group record a significant change of depositional setting and sediment source comparing with the rest of the Minas Supergroup. The Sabara Group occurs suitable for sedimentological-stratigraphical analysis in the Dom Bosco syncline, Moeda syncline and in the Serra do Curral. The Sabara Group was divided into the following ten facies, which occur in the field arranged in coarsening-upward (CU) successions: massive conglomerate (debris flow), coarse diamictite (debris flow), fine diamictite (debris flow), mixed greywacke (mass flow), arkosic greywacke (mass flow), tabular sandstone (turbidity currents), rhythmite (turbidity currents), siltite (low-density turbidity current), pelite (deposition of suspension) and black shale (deposition of suspension). These facies deposited in a talus fans/submarine fans/basin system tract. The Sabara Group represents foreland basin deposits related to the Transamazonian Orogeny. The clast suite of the diamictites and conglomerates points to erosion and reworking of supracrustal sequences (Minas Supergroup and Rio das Velhas Supergroup) and uplifted basement. The Sabara Group provenance plots show mixed source areas, predominating intermediate igneous and quartzose sedimentary provenance, although felsic and mafic igneous also contributed. These data indicate a compartmentalized, complex source area. The tectonic setting plots indicate a provenance from active continental margin/continental magmatic arc. The Sabara Group represents probably a Transamazonian compartmentalized foreland basin development during deformation uplift and erosion of Archean and Paleoproterozoic deposits of the Mineiro Belt. The Sabara basin, based on the location of its deposits and petrofacies, can be divided into three sub-basins: Antonio Pereira-Ouro Preto-Mariana-Rodrigo Silva, Lagoa das Codornas and Sabara-Belo Horizonte-Ibirite-Fernao Dias sub-basins.