Geoarcheology in Argentina

CULTURAL AND ENVIRONMENTAL EVOLUTION IN THE MERIDIONAL

SECTOR OF THE PUNA OF ARGENTINA DURING THE HOLOCENE .

Simposium I. Late Quaternary Palaeoenvironments, Climate and Culture.

Daniel E. Olivera¹ y Pablo Tchilinguirian²

1. UBA, CONICET, INAPL, e-mail: deolivera@movi.com

2. UBA, SEGEMAR, e-mail: sipol@sion.net

The research area involve sectors of the Antofagasta de la Sierra (Catamarca Province, Argentine, 26ºS, 67.5ºW) with a very bad previous knowledge in a archaeological and paleo environmental point of view. The main objective of this research is analyze the evolution of the paleo environment and its relationship with the resources availability for the archaeological human groups. The interest is focalized in new and important paleo ecological and archaeological record in the direction of produce models to understand the relationships between both climatic and cultural changes at a micro and macro regional levels. In direction to obtain the record and testing the hypothesis we proposed a cross-disciplinary study with methods and techniques from archaeological, geological and biological sciences, but in an adequate and integrated approach.

A Holocene sediments sequence from ancient lake and peat alluvial terraces, were studied by sedimentary paleoenviromental facies, diatoms and stable oxygen and carbon isotope analyses of charcoal and organic aquatic plants. Assumed periods of decreased lake volume in a relatively dry climate are characterized by enrichment in ¹⁸O and ¹³C and a higher concentration of clastic component, coarser grain size and decreased organic matter. In contrast to this situation, intervals of more humid climatic conditions give rise to increased lake volume with relatively depleted isotopic ratios and peat forming facies.

More humid conditions develops 9.900-8.700 yr B.P., maximum dry events between 6.300 to 3.900 yr B.P. Evidence of other significant wet phases occurs 2800-1600 yr B.P.

In general terms we can argue that in the Early Holocene human populations had to face a colder and more humid climate than today, but these conditions changed radically in the Middle Holocene. This change, however, does not seem to be really abrupt; it may have started in ca. 8.700 yr B.P., to be generalized about 6.000 yr B.P. During that time, human populations seem to modify their mobility conditions and subsistence strategies, including perhaps some initial intents of domestication. Before this phase, the natural environments of the peats in thin and deep gorges expressed less environmental variability, whereas the large valleys, such as the alluvial fan of the lower basin of the stream and lakes expressed the strongest variations in the sense of water availability and grass areas. In this way, the hypothesis about the existence of ecorefuges (Nuñez et al. 1999) was more probable for the environments that have now peats, mainly between 6.000 and 5.000/4.500 yr B.P.

Later there was a better climate with a wetter environment where the domestication of camelids had a new and strong impulse. About 2.800 yr B.P. a new cycle of high humidity started, that would help the adaptations of pastorals societies with the incorporation of agriculture and a logistics based on the use of environmental patches from highly sedentary Residential Bases.

When in 1.650-1.700 yr B.P. the conditions were less humid, there seems to be a new and radical change in settlement patterns. The driest point in 1.000 yr B.P. seems to coincide with the incorporation of new technological criteria for agriculture by the use of artificial watering in lands with more slope. It seems that, before moving to more apt environments or diminishing their number, the populations choose to incorporate better yieldings thanks to new technology.

References

2005 Olivera D. y Tchilinguirian P. Human Enviroment Interactions in Hemisphere Actions. Past, Present and Future. 2 nd. Southern Deserts Conference. Arica. Chile.