El "piso Aymará" de la región pampeana de la Argentina. Cronología radiocarbónica y paleontología

Abstract

Florentino Ameghino characterized the "Piso Aymará" (Aymaran Stage, also known as "Aimarense", "formación ayrnará" or "horizonte aymará") as a much more widely encompassing unit than later authors such as Frenguelli. This author considered that the "Aimarense" was only represented by an A horizon buried by eolian sediments. In this paper, we discuss the validity of the "Aimarense" and the record of some mammals from it, describe a profile in a locality where Frenguelli recognized the "Aimarense" in Miramar, and give a radiocarbon date (1870 ± 50 C-14 yr BP). We consider that the so called "aymaran stage" is not a chronostratigraphic unit in the sense both of Ameghino and Frenguelli. The "Aimarense" soil of Frenguelli is correlated with the Puesto Berrondo Soil. Most mammals atributed to the "Aimarense" were actually found in the eolian sediments and indicate a drier-than-present climate.