quadrilatero

Revista Brasileira de Geociências

Luciana Andrade Reis et al.

32(1):27-42, março de 2002

A BACIA DE ANTEPAÍS PALEOPROTEROZÓICA SABARÁ, QUADRILÁTERO
FERRÍFERO, MINAS GERAIS

LUCIANA ANDRADE REIS1, MARCELO A. MARTINS-NETO1,2, NEWTON SOUZA GOMES2, ISSAMU ENDO2
& HANNA JORDT-EVANGELISTA2

ABSTRACT THE PALEOPROTEROZOIC SABARÁ FORELAND BASIN, IRON QUADRANGLE, MINAS GERAIS, BRASIL The Sabará
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 Sabará Group record a significant change of depositional setting and sediment source comparing with the rest of the Minas Supergroup. The Sabará Group occurs suitable for sedimentological-stratigraphical analysis in the Dom Bosco syncline, Moeda syncline and in the Serra do Curral. The Sabará 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 Sabará 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 Sabará Group provenance plots show mixed source areas, predominating intermediate igneous and quartzose sedimentary provenance, although felsic and mafic igneous also contributed.