CONICET | Buscador de Institutos y Recursos Humanos

The Argentinean Mesopotamian region is a plain limited by large rivers, with an interesting environment historyand climate changes, especially during late Neogene and Quaternary periods. Within the Mesopotamia,Corrientes Province is particularly attractive due toits current vegetation and geomorphological characteristicswhere the Eastern-Northwestern migration of the Paraná River has played an important role. This migration inturn, allowed the sedimentation of the main geological units in the Pliocene -Pleistocene interval. The outcropsof the Ituzaingó (Pliocene) and Toropí/Yupoí (late Pleistocene) formations are widely distributed in Corrientes,and include numerous fossil remains of plants, invertebrates, and vertebrates (mainly mammals). Despite thepaleontological and stratigraphic studies carried out, the data are still insufficient to reconstruct how the en-vironments varied and how the migration of the Paraná River could have affected the vegetation during the lastpart of the Cenozoic. In this contribution, the first detailed study of the phytolith assemblages is accomplished,characterizing the Ituzaingó and Toropí/Yupoí formations in order to infer the palaeoclimatic and vegetationchanges during the late Cenozoic in this area of the Mesopotamian region. Four sampling localities (BV1, BV2,E1, and E2) were selected in two sites (Bella Vista and Empedrado). The recovered associations were useful forenvironmental reconstructions. Both formations are fluvial deposits related at different times to the currentParaná River. The phytolith assemblages of the Ituzaingó Fm. evidence the different ways in which the biosilicaelements were affected by pre and post-depositional processes. The Toropí/Yupoí Fm. shows well-preservedassemblages that suggest heterogeneous vegetation communities, with wetlands and grasslands to savannas andforests on the floodplain environments under seasonal subtropical climates.