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A GLACIAÇÃO NEOPALEOZÓICA NA PORÇÃO MERIDIONAL DA BACIA SANFRANCISCANA

1994; Sociedade Brasileira de Geologia; Volume: 24; Issue: 2 Linguagem: Inglês

10.25249/0375-7536.19946576

2177-4382

JOSÉ E.G. CAMPOS, MARCEL A. DARDENNE,

Geography and Environmental Studies

This text represents a stratigraphic and environmental study of two areas in the northwest of Minas Gerais State, Brazil.The work allowed the identification of the Permo-Carboniferous glaciation in the Sanfranciscana Basin, not yet described.A stratigraphic subdivision is proposed for the glaciogenic strata -The Santa Fé Group -which is composed of the Floresta and Tabuleiro Formations.The Floresta Formation is the basal unit and is composed of three members: Brocotó Member (tillites and tilloides), Brejo do Arroz Member (red mudstones and siltstones with a variety of dropstones) and Lavado Member (red sandstones).The Tabuleiro Formation (homogeneous sandstones) overlies all members of Floresta Formation.The arkoses of the Três Marias Formation (Upper Proterozoic) are the regional basement for the glaciogenic sequence.The Santa Fé Group is a proglacial system with tillite and tilloide facies (Brocotó Member), fluvioglacial facies (Lavado Member), glacio-lacustrine and turbiditic facies (Brejo do Arroz Member) and periglacial eolian facies (Tabuleiro Formation).The glacial sedimentation was controlled by the advance and retreat of the ice sheet.Diagenetic reactions are not well developed because of the incipient burial history.The major diagenetic feature was a calcitic pervasive cementation.The provenance areas for the glaciogenic deposits are interpreted from heavy mineral analysis, striated pavement orientation and dropstone composition.The northern Espinhaço region is proposed as the source area.