PALEOCLIMATIC VARIATIONS IN THE CORDOBA HILLS (ARGENTINA). OPAL PHYTOLITHS ANALYSIS FROM ARCHAEOLOGICAL SITE EL ALTO 3. FIRST APPROACHES

LÓPEZ, LAURA; RIVERO, DIEGO EDUARDO; CINGOLANI, ANA; GIORGIS, MELISA

Universidad Austral de Chile, Valdivia, Chile

Simposio; II International Symposium “Reconstructing Climate Variations in South America and the Antarctic Peninsula over the last 2000 years”; 2010

Universidad Austral de Chile, Valdivia

Silicon Phytoliths analysis on sediment is a useful tool for geologists, botanists and archaeologists because it gives direct evidence for the reconstruction of past climate, vegetation and human activities. The microfossil study makes possible to see little fluctuations within the steady general climate of the region, so we will probably understand the environment where ancient human groups moved. Soil samples from the archaeological site El Alto 3 (Cordoba Hills, Argentina) from present to ca. 7100 BP were analyzed and were identified into three Poaceae subfamilies grasses (Pooideae, Panicoideae and Chloroideae) that are climatic indicators. Then, both Temperature and Humidity indices were taken from relative percentages of opal phytoliths according to international criteria and Temperature and Precipitation indexes were worked out in the study region by considering the current subfamilies grass/climate relationship obtained from 437 floristic samples. This data was compared with geological studies in the region and we can note that these geological analysis present climatic changes in Center of Argentina but silicon-phytoliths analysis shows certain variability within each period of Holocene. At El Alto 3, the general climate of Holocene was very cool and very humid with fluctuations toward less humid and less cold and viceversa. For the last 2000 years, there has been change that foretells a Little Ice Age (LIA) with a trend toward a colder and less humid climate.