Early human occupation during Late Pleistocene-Early Holocene transition in the highlands of the Southern Atacama Desert (24.5°S, Northern Chile)

SANTANDER, B.; MALDONADO, A.; FAUNDEZ, W.; DE POL-HOLZ, R.; DE PORRAS, M.E.; URIBE, C.; CARTAJENA, I.; RIQUELME, R.; NUÑEZ, L.

Congreso; 20th Congress of the International Union for Quaternary Research (INQUA); 2019

During the Late Pleistocene-Early Holocene an extensive humid event known as the Central Atacama Pluvial Event (CAPE II) characterized by increased rainfall on the western slope of the Andes resulted in higher lake levels above 4000masl and increased groundwater table levels, leading to the formation of extensive wetlands at ca. 3000 masl. A large number of early sites were found during this period (ca. 12.6-11 and 10.5-9.5ka) along the borders of the Imilac and Punta Negra high altitude basins (ca. 3000 masl). However, at the end of the early Holocene (8.5ka), humid environmental conditions turned into extreme arid ones, coinciding with the abandonment of the sites, once the favorable conditions and resources disappeared. However, little is known about the occupations in higher altitudes during the Late Pleistocene-Early Holocene even when the presence of several ravines that drain into both high altitude basins and therefore, could have facilitate an easy mobility between the highlands and the Imilac and Punta Negra basins. Recent surveys conducted in the heads and highlands of the ravines (Guanaqueros, Zorras, Zorritas, Llullaillaco, 3.900-4.200 masl) showed a high abundance of biotic resources (specially vicuñas and guanacos) and the presence of early sites in each of them. Among the recovered diagnostic elements, monofacial artifacts widely represented in the early occupations of Imilac and Punta Negra stand out, as well as triangular projectile tips, typical of early occupations at local and regional scales. However, there are large differences in the lithic raw materials since these would be rather local or beloging to other sources different from those located in the Punta Negra (basalt) and Imilac (calcedony). The sites correspond mostly to open-air camps located on fluvial terraces around dejection cones that may have been active during times of high humidity. To date, only one site corresponding to the mid Holocene has been recorded under a rockshelter located at the head of the Llullaillaco ravine. Palaeoenvironmental evidence from highlands including fossil rodent middens records and palaeowetlands deposits into the ravines support the climatic scenarios of the Late Pleistocene-early Holocene at the local scale and provided a clear idea of landscape and depositional environments evolution from the early occupation stages to the final abandonment during the mid-Holocene. FONDECYT #1181627