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Description
This study presents the physicochemical and mineralogical characterization of a silicified angiosperm wood (15 × 30 × 11 mm), attributed to the Leguminosae family, from the El Palmar Formation (Pleistocene), outcropping in Mocoretá, Monte Caseros department, southeastern province of Corrientes, Argentina. Using a multi-technique approach that integrates X-ray Microcomputed Tomography (MicroCT), X-ray Fluorescence (XRF), X-ray Photoelectron Spectroscopy (XPS), and Confocal Raman Spectroscopy (CRS), the taphonomic and diagenetic processes responsible for its preservation are analyzed. CRS allowed the identification of polymorphic siliceous phases (opals, cristobalite, and tridymite) associated with ferric and clay phases, indicating a high availability of silica during early diagenesis. XRF analyses revealed the presence of Si, Ca, Al, K, Fe, Ti, Mn, Cr, and Ni, while XPS additionally detected O, C, N, Mg, Na, and Cu, providing critical information on the elemental composition and surface chemistry of the wood. MicroCT documents the three-dimensional preservation of the anatomical organization and permineralization patterns, while CRS records progressive transformations of the lignocellulosic matrix and a heterogeneous distribution of mineral phases. The high carbon/nitrogen ratio indicates selective preservation of recalcitrant organic matter under suboxic to anoxic conditions, in association with fluvial floodplain facies and paleowetlands. These results reveal a paleoenvironment of high geochemical complexity, controlled by abrupt climatic oscillations that alternated between temperate-humid and warm conditions, in line with the dynamics of Late Pleistocene interglacial systems. The systematic application of this multi-technical approach to the xylote fossil flora of the El Palmar Formation will substantially refine the resolution of paleoclimatic and paleoenvironmental reconstructions of the Argentine Mesopotamia during the Quaternary of the Southern Cone. In future stages, neutron tomography will be applied to elucidate the distribution and role of light elements and phases that are not detectable by X-ray-based techniques.