Reconstrucción paleoambiental del Cuaternario en las barrancas del Río Quequén Salado, provincia de Buenos Aires Argentina

SCHILLIZZI, R. A.; GUTIERREZ TELLEZ, B.; ARAMAYO, S.

Córdoba

Congreso; III Congreso Argentino de Cuaternario y Geomorfología; 2006

Universidad Nacional de Córdoba

ABSTRACT At the intermontane and piedmont region of the South East region of Buenos Aires province, Argentina, rivers like Quequén Salado, Indio Rico and Las Mostazas among others, modeled banks that have been subject of many geological studies. Thus, the aim of this work is to recognize the Quaternary unities cropping out at profiles along the banks of the Quequén Salado river, in order to infer palaeoenvironmental changes and correlations among them. Methodology included sediment analysis, identification of microfossils (diatoms, gastropods, etc.), macrofossils (mammal fossil remains) and plant root traces and stem concretions. As a result, the presence of sedimentary unities named La Chumbiada, Guerrero and Río Salado from Lujan Formation were registered (Late Pleistocene – Early Holocene). From a palaeoenvironmental point of view, pool- fluvial and marshy conditions are inferred at the base of the profiles, where remains of Panochthus sp.(Xenarthra, Glyptodontidae) were registered (carapace and post cranial skeleton). Besides, lower sections of the profiles are related to fluvial plains meanwhile upper sections are referred to freshwater or brackish oxygenated and vegetated shallow pools, supporting a varied micro and macrofauna, together with sapropel intercalations deposited by ephemeral streams. Even, the presence of buried soils were registered, one of them equivalent to Puesto Callejón Viejo. At the upper sections of the profiles, the Río Salado Member (Holocene) represents pool environments that evolved towards fine laminated diatomitic deposits formed in brackish conditions.