Open AccessFácies sedimentares e elementos arquitetônicos das Formações Serra do Apertado e Pedra Pintada na Região das Minas do Camaquã - RS
Author(s) -
Lucas Padoan de Sá Godinho,
Renato Paes de Almeida,
Maurício Guerreiro Martinho dos Santos,
André Marconato,
Antônio Romalino Santos Fragoso-Cesar
Publication year - 2013
Publication title -
geologia usp. série científica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.237
H-Index - 21
eISSN - 2316-9095
pISSN - 1519-874X
DOI - 10.5327/z1519-874x2013000200003
Subject(s) - sedimentary depositional environment , geology , facies , fluvial , alluvial fan , sedimentary rock , context (archaeology) , paleontology , gondwana , aeolian processes , geochemistry , structural basin
The Guaritas Group (Cambrian, RS, Southern Brazil) encompasses sedimentary deposits of bedload or mixed load rivers,eolian dune fields and alluvial fans, and constitutes a rare sedimentary record of Cambrian age in Eastern SouthAmerica. In this context, its uppermost unit, named Serra do Apertado Formation, contains the last record of stabilizationphase of the Gondwana Continent in south and southeastern Brazil. Nevertheless, there are no published detailed studieson its facies and depositional architecture, and this unit has been considered as similar to the Guarda Velha Formationsince its original definition. Based on sedimentary facies and depositional architecture studies of the Serra do ApertadoFormation and the upper portion of its underlying unit, the Pedra Pintada Formation, the depositional environments werecharacterized and a descriptive basis was established to distinguish them from the other units of the Guaritas Group.The Serra do Apertado Formation is characterized by the architectural element EL (Sheet floods), which encompassesfacies associations that points to a fluvial system characterized by large discharge changes and occasional eolian reworkingof bar tops. The upper part of the Pedra Pintada Formation intercalates the architectural elements DB (barchanoiddunes) and IF (Fluvial interdunes). The exclusivity of EL in the Serra do Apertado Formation contrasts with previous descriptions of the Guarda Velha Formation, which show elements of channel-fill and frequent conglomeratic lenses. Those differencesreveal more eolian reworking in the Serra do Apertado Formation and possibly more episodic flow, suggesting, preliminarily,a dryer climate than the one recorded in the Guarda Velha Formation