CONICET | Buscador de Institutos y Recursos Humanos

The Mesopotamian region in Argentina is a plain limited by large rivers, with an interesting environment history and climate changes, especially during late Neogene and Quaternary periods. Within the Mesopotamia, Corrientes Province is particularly interesting due to its current vegetal and geomorphological characteristics where the Eastern-Northwestern migration of the Paraná River has played an important role. This migration in turn allowed the sedimentation of the main geological units in Pliocene and Pleistocene intervals. In Corrientes Province the outcrops of the Ituzaingó (Pliocene) and Toropí/Yupoí (late Pleistocene) formations are widely distributed, and include numerous fossil remains of plants, invertebrates, and vertebrates (mainly mammals). Despite the paleontological and stratigraphic data carried out, they are still not enough to reconstruct how the environments varied and how the migration of the Paraná River could affect the vegetation during the last part of the Cenozoic. In this contribution, the first detailed study of the phytolith assemblages is accomplished, characterizing both the Ituzaingó and Toropí/Yupoí formations in order to infer the palaeoclimatic and vegetation changes during the late Cenozoic in this area of the Mesopotamian region. Four localities were selected in two sites (Bella Vista and Empedrado). The different associations recovered were useful for environmental reconstructions. Both Formations correspond to fluvial deposits related at different times to the current Paraná River. The Ituzaingó Fm. phytolith assemblages evidenced the different ways in which the biosilica assemblages were affected by pre and post-depositional process. Toropí/Yupoí Fm. showed well-preserved assemblages and they suggest heterogeneous vegetal communities, with wetlands and grasslands to savannahs and forests on the floodplain environments under seasonal subtropical climates.

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