Abstract

PATTERER, Noelia I. Análisis fitolíticos de la formación San Salvador (plioceno−pleistoceno inferior) en la cuenca del río Uruguay, Entre Ríos, Argentina. Rev. Asoc. Geol. Argent. [online]. 2015, vol.72, n.3, pp.332-344. ISSN 0004-4822.

This paper describes the phytolith assemblages recovered in the San Salvador Formation (Pliocene−Lower Pleistocene), East of the Entre Rios province, Argentina. The methodological procedures were based applications of regional geology, geomorphology, stratigraphy and sedimentology principles and techniques, which consist primarily a task field and laboratory. The silica microremains were extracted using standard protocol for sediment samples, but adapted for fluvial sediments. Sedimentary strata were conglomerates mainly of gravels matrix supported and sands of grain size different, with internal and surface structures. The clays fraction was represented by major clay strata. The phytoliths were observed in sand layers of fine texture and mud. In the gravel strata, absence and / or shortage of phytoliths were recorded. Elongated, polyhedral and fan shaped phytoliths were abundant. Smaller phytoliths as globular, bilobate, truncated cones are oblong and crenate were present in both profiles. Collapsed saddles of bambusoideas affinity were very frequent in the Concordia profile samples. The phytolith assemblages study, represent the first fossil record of this sedimentological unit, integrated by Arecaceae, Poaceae (Bambusoideae, Panicoideae, Chloridoideae and Danthonioideae) and Podostemaceae families. These assemblages were originated by humid forest, palm and riparian forests paleocommunities and indicate humid tropical-subtropical climate with high water availability.

Keywords : San Salvador formation; Phytoliths; Río Uruguay Basin; Upper Cenozoic.