Análise icnológica no testemunho 2-gg-1-pr, grupo itararé (carbonífero superior da bacia do paraná)

Abstract

Ichnofossils are evidence of interactions between organisms and substrates that are recorded in geological time. In sedimentary rocks, trace fossils can be an important source of paleoecological information, allowing to track variations in oxygenation, salinity, sedimentary input, hydrodynamic energy, among other factors. Thus, ichnological analyzes can be applied to sedimentological, stratigraphic, palaeobiological, palaeoecological and palaeoenvironmental interpretations, both in outcrops and in subsurface sections. The strata of the Itararé Group have been extensively explored under a paleoichnological scope, revealing ichnofacies in diverse environments associated with glacial dynamics. This unit is characterized by glaciogenic rocks deposited during the deglaciation of Late Paleozoic Ice Age. Of the more than 1000 m thick, studies have focused mainly on rhythymitic facies where structures attributed to arthropod trails and invertebrate excavations are preserved. This study analyzed the 2-GG-1-PR core (Guaragi, PR), made available by the Sedimentary Geology Laboratory (LAGESED-UFRJ), which sampled the Lagoa Azul and Campo do Tenente formations (Itararé Group) containing several trace fossils, unreported to the unit. In this context, the ichnological analysis proposed here aimed to characterize the ichnofossils of the 2-GG-1-PR (Carboniferous of the Paraná Basin); to integrate sedimentological and ichnological data for paleoenvironmental interpretations of the Itararé Group; and to interprete the relationship between palaeoecological variations and glacial cycles. The interval focus of this study contains ichnofossils that correspond to expressions of Glossifungites, Phycosiphon and Cruziana ichnofacies, and indicate marine conditions associated with an omission surface, pro-delta context and shelf marine conditions, respectively, indicating environmental variations in a marine glacial context.