Lithofacies, depositional environments and cyclicity of the Paranoá Group: example from the Serra de São Domingos, Minas Gerais
DOI:
https://doi.org/10.11606/issn.2316-9095.v19-140467Keywords:
Facies, Mesoproterozoic, Coastal tidal flat, Mixed carbonate-siliciclastic succession, Storm bedsAbstract
In Serra de São Domingos (SSD), a succession of Mesoproterozoic rocks of the Paranoá Group comprises dominantly siliciclastic rocks along more than 1,000 m thick. Two stratigraphic sections were measured and described in scale of 1:300 and subdivided in eleven lithofacies: De (stromatolites dolomite), Dl (laminated dolomite), AFl (laminated fine grained sandstone), AFm (fine grained sandstone with wave and current ripple), AFh (fine grained sandstone with hummocky cross-stratification), AMc1 (medium grained sandstone with unidirectional cross-stratification), AMc2 (medium grained sandstone with bidirectional or ultidirectional
cross-stratification), AMe (stratified medium grained sandstone), AMs (medium grained sandstone with sigmoidal geometry), Pl (laminate pelite) and PAht (pelite and sandstone with heterolithic laminations). Five facies associations were identified: FA-I is characterized by lithofacies AFm and PAht, in an intertidal subsystem; FA-II is characterized by AMc1, AMc2, AMs, AMe in a subtidal subsystem; FA-III is characterized by lithofacies AFm, AFl, AFh and Pl in a proximal shelf with a tidal, wave and storms influence; FA-IV is characterized by lithofacies AFl, Pl, AFh, De and Dl, in an intermediate-distal shelf subsystem; and FA-V is characterized by lithofacies Dl and De in a shallow shelf subsystem. FA-III, FA-IV and FA-V facies’ associations were deposited in a mixed carbonate-siliciclastic depositional shelf system, while FA-I and FA-II were deposited in tidal flat. The depositional systems along the SSD range from deposits of the proximal offshore at their lower intervals, passing upwards to an inner platform with tidal influence (subtidal-intertidal), evidencing a shallow upward succession.
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