Spectroscopic and SEM-EDS studies of gymnosperm wood from the Upper Permian Tacuary Formation, Paraguay

Abstract

The mineralogical study and physicochemical characterization of petrified woods from the Tacuary Formation (Upper Permian) were conducted using samples from Arroyo Vino, Guairá Department. The methodologies included local observations, sampling, macroscopic observation, petrographic microscopy, scanning electron microscopy (SEM) with an energy-dispersive X-ray spectrometer (EDS), Confocal Raman Spectroscopy (CRS), and geographic information systems (GIS). Polymorphs of silica and heavy metal minerals were identified. This research detected the presence of iron, nickel, chromium, and traces of strontium, germanium, rhenium, and other transition metals. Additionally, the mineralization processes in fossil woods of the Tacuary Formation were interpreted in relation to the Guairá Basin, aiming to consider palaeobotanical aspects, infer the palaeoenvironment, the prevailing palaeoclimate in Eastern Paraguay, and highlight the palaeobiogeographical distribution of the taxon.