Registro Paleobotánico Del Plio–pleistoceno Inferior en El Valle Del Río Uruguay. Caracterización Fitolítica De La Formación San Salvador, Este De La Provincia De Entre Ríos, Argentina.

Abstract

PLIO-LOWER PLEISTOCENE PALAEOBOTANICAL RECORD IN THE URUGUAY RIVER VALLEY. SAN SALVADOR FORMATION, (EAST OF ENTRE RÍOS PROVINCE, ARGENTINA) PHYTOLITH CHARACTERIZATION.The San Salvador Formation is one of the few deposits from the Pliocene-Lower Pleistocene in the east of Entre Ríos Province, which from a palaeontological point of view has been described exclusively through its phytolith content. This contribution includes the synthesis and expansion of this knowledge through the results of the phytolith study of the José Etchepare Hijo profile (Colón Department, Entre Ríos). For this, an ad-hoc methodology has been used, adapted to obtain phytoliths in fluvial deposits. The sedimentary sequences were characterized by a succession of conglomerate supported matrix strata, fine to coarse sandy facies and fine facies (represented by clays and silts). The results allowed to observe a greater abundance and variability of phytoliths in layers with sandy texture; and proportionally more scarce and even absent in the gravel texture layers. Non-diagnostic grass phytoliths were common in all the samples with microremain materials, while among those of smaller size and diagnostic ones, their presence was manifested only in certain sectors of the profile. The phytolith assemblages were made up of elements from the Arecaceae, Poaceae (Bambusoideae, Panicoideae, Danthonioideae, Chloridoideae and Pooideae), and Podostemaceae families; and they have allowed inferring palaeocommunities of stratified hygrophilous forests, palm groves and riparian forests, which indicate a humid tropical-subtropical climate, with great water availability.