Fácies e associações de fácies de diamictitos do Subgrupo Itararé (Paleozóico superior) no norte de Santa Catarina e sul do Paraná, Bacia do Paraná, Brasil

Abstract

Glacial diamictites provide information about glacial depositional environments. Similar characteristics found in other sediments, however, may lead to incorrect interpretation of diamictites since any sedimentary type can be deposited by glaciers. In addition diagenesis, compaction, water loss and weathering may obliterate diagnostic features. Most of the problems of interpretation of glacial sucessions must therefore be classified together with those related to the origin of the diamictites using the identification of sedimentary facies. These facies are compact massive diamictite; deformed diamictite; non compact massive diamictite; tabular diamictite; lenticular diamictite; laminated diamictite with massive diamictite lenses; clast rich massive diamictite; stratified diamictite with textural variation or intercalations of other rock types; diamictite with intercalations of various rock types containing icnofossils; and rhythmite of diamictite and shale. This approach was based in the interpretation of such facies in order to identify their paleoenvironmental setting. The diamictite facies were thus combined into facies associations or groups of facies genetically related, and with environmental significance. In regard to the fact that the interpretation of a sedimentary environment can rest on the association of universal facies with other diagnostic facies, their groups here recognized took into account those produced under specific depositional conditions related to the admitted glacial terrestrial and glacial-marine influences in the study area. So, terrestrial grounded glacier association, proximal platform grounded glacier association and distal platform association were defined.