Description of Ex Situ Microbialites From Pedra de Fogo Formation (Permian, Parnaíba Basin) in the Municipality of Teresina, Piauí

Abstract

Microbiolites are laminar structures resulting from the action of microorganisms. They are the oldest evidence of life on Earth being recorded since the Eoarchean. They are an important element for paleoenvironmental analysis due to their growth dynamics that are influenced by environmental factors, making it possible to associate their various forms to certain environments. This study aims to describe the microbialites of the Pedra de Fogo Formation (Lower Permian) found on the banks of the Rio Poti, in the South Zone of the municipality of Teresina, PI. The material was collected on the banks of the Rio Poti in the southern part of the city. The best-preserved material was separated according to its morphology into columnar, pseudocolumnar, domal, oncoid and mats. Among the material, several types of laminations can be observed, showing repeated cycles that may indicate environmental seasonality. The analysis of the vertical variations of the growth bands showed an environmental cyclicity with moments of greater luminosity represented by wider bands and moments of lower intensity shown by shorter bands. The scarcity of research on these fossils in the unit highlights the relevance of this study in contributing to the understanding of the paleoenvironment of this region, also serving as a source of data for future work in the area.