The Ensenadan Stage-Age of southern South America: Its stratigraphic, biostratigraphic and chronological implications in present research

18- RABASSA, J., TONNI E.P, A.A. CARLINI

QUATERNARY INTERNATIONAL

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2009 vol. 210 p. 1 - 3

1040-6182

The Ensenadan Stage/Age is a very important period of the Quaternary history of southern South America. Though its time boundaries have not been defined with absolute precision, it probably extends from the earliest Early Pleistocene, ca. 2 Ma (Olduvai event), to the Early Middle Pleistocene, around 0.5 Ma. Its original name and definition come from the sedimentary beds and their paleontological content found in the excavations of the harbour of Ensenada, a town located very close to the city of La Plata, Buenos Aires Province, on the western shore of the Rı´o de la Plata estuary, which were done in the late 1800s. The Ensenadan Stage/Age in its type area is developed during the genesis of the Ensenada Formation, loess and loess-like sediments and fluvial units. Inter-bedded marine coastal and littoral deposits were originally described by Florentino Ameghino, but their occurrence has not been undoubtedly confirmed since then. The Ensenadan Stage/Age is based upon the Mesotherium cristatum Biozone, which is spatially coincident with the Ensenada Fm. It comprises the epoch when an outstanding paleontological content demonstrated the evolution of, in particular, a very rich mammal fauna, as well as birds and other fossil vertebrates. Evidence of these times is present not only in the fossil vertebrates, but in marine molluscs, pollen content and sedimentary records as well, all of which are timely coeval with the Ensenadan Stage/Age of the Pampas