CONICET | Buscador de Institutos y Recursos Humanos

The phytolith assemblages of the El Palmar Formation (Late Pleistocene) are presented together with generalstratigraphic and sedimentological data. The El Palmar Formation represents a channel system of the Uruguayriver (South America) with longitudinal sandy gravel and gravelly sand bedforms, and associated floodplaindeposits. The phytolith content of the unit was analyzed along the profiles on the right bank of the river in themiddle reach (eastern Entre Ríos province, Argentina). Four outcropping profiles of the El Palmar Fm. wereselected for detailed analyses: Santa Ana (Federación department), La Chola quarry, El Palmar National Park andNueva Escocia (Colón department) localities. The herbaceous palaeoflora of the El Palmar Fm. is represented bymixed environments, such as meso-megathermic grassland with the presence of palm trees in a savanna ecosystemand micro-environments with aquatic plants and bamboo grasses that characterized a stratified forest inhumid environments with high water availability. The reconstructed vegetation pattern is composed of a stratifiedgallery forest changing to temperate savanna, extended along the upper basin of the Uruguay river andoccupying the river valley in the middle reach of the basin. The data contribute to the palaeobiodiversityknowledge of Quaternary fluvial sedimentary units of South America. In addition, the results give a betterunderstanding of the evolutionary history of some vegetal communities, and especially the present palm trees ofthe El Palmar National Park reserve, as part of a relict flora that has inhabited the area since, at least, the UpperPleistocene. The geological and micro-paleobotanical records of the El Palmar Fm. lead to the inference ofgeneral warm and humid conditions during most of the deposition of the formation, probably covering part ofthe last major interglacial period before the present (MIS 5).

enviar mensaje