Palaeoenvironmental changes at Alero El Puesto (AEP-1) archaeological site (Deseado Massif). Regional palaeoclimate implications and early human occupation.

BORROMEI, A.M.; MUSOTTO, L.L.

Archaeology of Piedra Museo locality: an open window to the early peopling of Patagonia

Springer

Año: 2022; p. 159 - 178

Interpretation of pollen data from Alero El Puesto (AEP-1) archaeologicalsite at Piedra Museo locality (47° 53 42 S, 67° 52 04 W, 150 m a.s.l.), in thenorthern Deseado Massif, allows to improve the knowledge about the palaeoenvironmentalconditions following the Last Glacial Maximum, and their relationship tothe early human occupations. Two climatic events featured the late Pleistocene?earlyHolocene transition, the Antarctic Cold Reversal (ACR, ca. 14,600?12,800 cal BP),and the Northern Hemisphere Younger Dryas event (YD, ca. 12,900?11,700 cal BP).The vegetal palaeocommunities reconstructed from pollen records from the DeseadoMassif region reflected abrupt changes related to both temperature and precipitationduring these events. Cold and extremely arid conditions characterized theACR, whenvegetation was dominated by shrub steppes with Asteraceae subf. Asteroideae anddwarf shrub steppes with Ephedra. Meanwhile, the spread of grassland steppes withvariable proportions of shrubs and dwarf shrubs, coeval with the YD, suggested achange towardwarmer and slightly wetter conditions than before. The archaeologicaldata showed an increase in the human use of space during this interval. After that,the trend of increasing temperature and decreasing effective moisture favored thedevelopment of a mosaic of shrubby steppes during the early Holocene. The floristicallyheterogeneous shrub steppes began to dominate the Deseado Massif duringthe middle and late Holocene. This vegetation reflected arid to semiarid conditionsindicating rainfall spatial variation, runoff redistribution, and edaphic diversity. Plantpalaeocommunities similar to the present-day ones were established in the north ofthe Deseado Massif after ca. 4000 cal yr BP, and in the south of this massif afterca. 2100 cal yr BP. Taken together, the palaeoenvironmental conditions recorded in the studied region are closely related to variations in the latitudinal position and/orstrength of the westerlies that would have impacted the early human occupations.