Biomorfos de sílice en secuencias pedoarqueológicas del sitio Paso Otero 5, Buenos Aires

OSTERRIETH, M.; MARTÍNEZ, G.; GUTIÉRREZ, M. Y M.F. ALVAREZ.

Matices interdisciplinarios en estudios fitolíticos y de otros microfósiles. British Archaeological Reports (BAR), Oxford. Korstanje, M. A. y M. P. Babot (Eds.).

British Archaeological Reports (BAR), Oxford.

Año: 2008; p. 77 - 90

Archaeological and paleoenvironmental studies has been carried out in Paso Otero 5 site. Faunal remains of both extinct and modern species associated to “fish-tail” projectile points were found in the archaeological component (ca. 10,450 - 10,200 years BP). The stratigraphic sequence ranges from the Pleistocene-Holocene transition to the Late Holocene. The aim of this paper is to study the assemblage of silica biomorphs (poriferous, diatoms, chrysophyseae cysts), specifically the silicophytoliths. The results allowed to recognise two major groups: I) bottom of the sequence (ca. 12,000 - 10,450 years BP) represented only by silicophytoliths (less than 10%) which are indicative of a scarce vegetal cover under arid to semi-arid conditions; II) top of the sequence (ca. 10,450 - present) whereas the silicobioliths are dominant (>50%), indicating an increase in the vegetal cover developed under more humid conditions. During ca. 10,450/9400 years BP warm-humid conditions were registered followed by a hydric restriction which it lasted to ca. 8800 years BP. A change to environmental stability is recorded during this time. Hydric restrictions have been inferred towards ca. 7800 years BP and dry conditions continued and incremented between ca. 6600 - 4200 years BP. A rapid change towards more humid environments is registered ca. 2500 years BP and finally, a brief pulse of intense hydric restriction is identified at the top of the sequence. The analysis of the phytoliths would indicate rapid environmental changes in the plains during the Pleistocene-Holocene transition and the Late Holocene.