Paleoenvironmental conditions and changing early occupations of the south of the Deseado Massif (Patagonia, Argentina)

MANCINI, M.V.; BAMONTE, F.P.; FRANCO, N.V.; BROOK, G.

Bern

Congreso; XVIII INQUA Congress; 2011

Preliminary findings indicate that the southern part of the Deseado Massif in the Santa Cruz Province, Argentinean Patagonia, was being utilized by human populations at least by 10,845 ± 61 14C yr BP (12850 cal yr BP). The information recovered -size for the site and the hearths, as well as artifact characteristics-, suggest that during the Pleistocene-Holocene transition La Gruta cave was used repeatedly for short periods of time by a few to several people. Pollen analysis from different sequences allows reconstructing the paleoenvironment during the previous and the contemporaneous occupation times. Thus, during the Pleistocene-Holocene transition pollen sequences from the extra-Andean central plateau region show a dwarf shrub steppe with high values of Ephedra suggesting arid conditions different from the modern ones with precipitations lower than 200 mm. To the west pollen spectra from a wetland core located at south of Lake San Martín, near the eastern limit of the Subantarctic Forest – Patagonian Steppe ecotone, also show a dwarf-shrub steppe with high values of Ephedra under arid conditions similar to the ones in the present day extra-Andean area. At the beginning of the Holocene, along the ecotone forest-steppe and in the central plateau, the sequences analyzed indicate that a grass steppe dominated up to ca 8000 cal yr BP suggesting higher moisture availability due to an increase in precipitation (ca 300 mm annually), while Nothofagus forest expansion started in the Andean zone. The increase in organic matter at the beginning of the Holocene could be related to an increased temperature. Archaeological evidences of human utilization of the southern part of the Massif increase by ca. 8,000 14C yr BP (ca. 8830 cal yr BP). By this time, there is a change in the size of the hearth at La Gruta cave, as well as more abundant evidences of utilization of spaces located close to the north. VER: file:///C:/Users/Flor/Desktop/XVIII.%20INQUA%20Congress%20%20%20Quaternary%20sciences.htm