CONICET | Buscador de Institutos y Recursos Humanos

The Potrok Aike Lake, is a maar lake present in the Plio-Pleistocene back-arc volcanic field (Pali Aike Volcanic Field) located in Santa Cruz province (52° S and 70° W; 113 m a.s.l.), Argentina. The PASADO project is an interdisciplinary scientific project that has successfully drilled their lacustrine sediments, obtaining a drilling covering a period of 50 ka BP. From this sequence, in the present communication, phytolith composition of a section ranging from 21301.1?27799.3 ka BP (or 2657.6?3381.0 cm deep from Site 2) has been studied. This section, belonging to the lithological unit C-1, is composed by pelagic laminated silts intercalated with thin fine sand and coarse silt layers, with poor lamination, and their analysis show the presence of three phytolith zones: the lower zone (27799.3?24765.2 ka BP) without reworked levels and characterized by demarcated high rarefaction in their phytolith composition and phytolith assemblage that has an abundance of festucoids, pooids, bromoids and arundinoids phytoliths. A middle mixed zone (24572.5?23513.7 ka BP) characterized with the presence of reworked level gaps, and a trend to lower rarefaction in upper levels, as well as scarce relative abundance of the graminoid elements mentioned above. Some dicot shrub and/or arboreal elements are most abundant in this zone. The upper zone (23477.6?21301.1 ka BP, with a reworked gap around 22374.3 ka BP) show low phytolith rarefaction and clear dominance of festucoids and dicots shrub and/or arboreal elements, although they are occasionally other graminoid components.