Obsidian sources from the southern Andean highlands (Laguna del Diamante, Argentina and Chile): geochemical insights on human biogeography

CORTEGOSO, V.; YEBRA, L.; DURÁN, V.; CORNEJO, L.; BARBERENA, R.; LUCERO, G.; GIESSO, M.; MACDONALD, B. L.; GLASCOCK, M. D.

Simposio; 11th International Symposium on Knappable Materials; 2017

In this poster we synthesize the geochemical results available for obsidian sources and artifacts from the highlands of Mendoza Province (Argentina) and the Maipo River valley (Chile). These results improve our understanding of the geochemical resolution of three different source deposits and, have enabled us to reassess patterns of human mobility reconstructed on the basis of artifact distributions. The focus is on Laguna del Diamante area, which is a high-altitude enclosed wetland (3300 masl, 34°S) with accessibility that is restricted to the austral summer months, during which time it occupies a key position in intermountain circulation paths. Since 2007, a total of 421 samples from sources and archaeological sites in the area and proximate basins were analyzed by means of two non-destructive energy-dispersive x-ray fluorescence (XRF) spectrometers: Elva-X table top and Bruker III-V portable from the University of Missouri Research Reactor. Three geochemical signatures dominate the regional archaeological record: the first corresponds to the local Laguna del Diamante chemical type, presenting an archaeological distribution that is restricted to within or nearby the lagoon. The second chemical type corresponds to Arroyo Paramillos, whose source has not yet been identified in the field. At an archaeological level, this type has a distribution centered in the lagoon and heavily skewed towards the western slope, along the Maipo River basin. Finally, a third source known as Nieves Negras has been recently identified in the upper Maipo River basin. This new finding has enabled us reassess its distribution at archaeological sites.