PALEOECOLOGICAL INVESTIGATIONS IN THE PAMPA SECA, ARGENTINA BASED ON A MULTI-PROXY APPROACH

ISABEL VILANOVA; KARSTEN SCHITTEK; MATHIAS GEILENKIRCHEN; WILFRIED SCHULZ

Heilderberg

Congreso; The 23rd Latin American Colloquium on Earth Sciences; 2014

University of Heilderberg

The Pampa Seca is a preferential area for the reconstruction of the younger quaternary environmental evolution. It contains more than 200 water-filled deflation pans, which provide (1) geomorphological archives containing information about the past wind systems concerning the quality (direction) and quantity (the volume of transported material); and (2) lake sedimentary archives, covering information about the ecology of the environment (palynomorphs and charcoal). Laguna Nassau, one of those water-filled deflation pans, is located at the northeastern edge of the Pampa Seca. Radiocarbon dating suggests that the deposition of lacustrine sediments in this pan started not before 1630 +/- 35 BP. We conducted a multi-proxy approach with the aim to provide a high-resolution study of the past 1600 years in order to reconstruct environmental and vegetation changes related to geomorphological evolution and climatic conditions. The pollen spectra consists primarily of three groups of taxa, (1) the surrounding grassland and sand dune vegetation, (2) the xerophytic woodland, the so-called Caldenal, and (3) the local vegetation, represented by semi aquatic and aquatic taxa (Typha, Ruppia and Potamogeton types). The curves of other palynomorphs like Botryococcus and Pediastrum along with those from fungus reflect variations in the stability in water level/depth and environmental conditions such as moisture and salinity over time. The geochemical and geophysical analyses and macroscopic charcoal show that fire played a significant role during warm periods which coincide with a lowering water level suggested by palynological spectra; also these analyses indicate that the implementation of agriculture yielded the occurrence of erosional processes that have induced a strong change over the environment.