Spectroscopic studies on Permian plant fossils in the Pedra de Fogo Formation from the Parnaíba Basin, Brazil

The “Pedra de Fogo” Formation dated from the Permian period (approximately 280 million years ago), belongs to the sedimentary Parnaiba Basin, located in the northeastern region of Brazil. It is recognized by their well preserved fossil contents and it is notable for having several fossilized trunks in the growing position. Specimens from different localities were selected in order to perform spectroscopic studies and X-ray diffraction analysis, as well, for the purpose of identifying and characterizing compounds related to the fossilized materials. These different techniques allowed to obtain information from the molecular spectra in organic and inorganic substances, which are present in these above stated fossils and in the atomic elements, as well as the crystalline phases. These aforementioned studies have revealed promising paleoenvironmental interpretations about their depositional strata. Regarding the techniques, these have enabled inferences with respect to the fossil diagenetic events and allowed a better understanding of the fossilized process and the mineralogical characteristics of the living environment, where the plants were buried. This study presents physical and/or chemical properties of the fossilized plants through vibrational spectroscopies, SEM/EDS spectroscopy and X-ray diffraction techniques. Based on the results duly obtained, we were able to identify the presence of silica and confirm that the dominant process of the fossilized specimens investigated has occurred through quartz silicification with the contribution of persistence from amorphous carbon.