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

Abstract

New geochemical results for two obsidian types, Laguna del Diamante and Arroyo Paramillos, naturally available in the Laguna del Diamante locality, a seasonally accessible highland wetland emplaced in the current border between Argentina and Chile at 3300 masl (34 degrees S), are presented. A total of 1219 archeological artifacts from 41 sites located on both sides of the Andes have been assigned to these sources. The artifacts were analyzed by non-destructive, energy-dispersive X-ray fluorescence (ED-XRF). Archeological distributions of these obsidian types are assessed through GIS spatial analysis. Results show a great asymmetry in the distribution of these sources toward the two Andean slopes: the Laguna de Diamante chemical type shows a fairly local use pattern, being concentrated almost entirely in Cordillera sites, but the Paramillos shows a less homogeneous distribution and tends to be more concentrated in the sites that are in the western natural corridor. Although these lands were accessed and occupied from diverse demographic nodes in lower-altitude settings, the spatial analysis of obsidian artifacts reinforces the argument of dominant geographic vectors of access connecting with the western valleys and lowlands of Chile.