Evidences of life in Proterozoic deposits of the Camaquã Basin (S Brasil): a synthesis

This paper aims to synthesize the knowledge of the biogenic structures preserved in some beds of the Terminal Proterozoic basins of southern Brazil. Simple horizontal (Cochlichnus, Planolites, Palaeophycus), meandering (Gordia, Helminthoidichnites), and probing (treptichnid morphologies) feeding burrows, horizontal (Arthraria) dwelling burrows and plug-shaped (Bergaueria, Beltanelliformis) resting burrows, medusalike and ‘Vendobionta’ basal disk imprints (Aspidella, Cyclomedusa, Charnia, Intrites, Panvarcorina, Sekwia), and microbially induced sedimentary structures (Arumberia-type structure, Kinneyia-type structure, elephantskin structures, wrinkle structures, Chancelloria-like structures, among others) occur in Camarinha (Paraná State), Itajaí (Santa Catarina State), and in some stratigraphic units of the Camaquã (Rio Grande do Sul State) basins, conferring an Ediacaran age for these deposits. Most of these records are preserved chiefly in fine-grained turbiditic beds originally assumed as nonmarine, and at the soles of braidplain delta sandstones (in the Camaquã Basin). The biota composition is similar to the Ediacaran biotas from Avalonian terrains, suggesting a pathway between these terrains and the Rio de la Plata craton during the Ediacaran.