Artículo de publicación ISIWe present the results of XRF analysis for 428 obsidian samples from archaeological sites in the Argentinian province of Mendoza and from central Chile. The archaeological samples come from different environments and have dates that range from 9000 to 300 BP. The results indicate that all known sources were utilized; however, the beginnings and the intensities of their exploitation were variable. On the contrary, strong differences appear, especially between the Cordilleran and the non-Cordillera sources. We suggest that this pattern is mainly related to differences in the accessibility, quality and abundance of the obsidian in the sources.Agencia Nacional de Promocion Cientifica y Tecnologica of Argentina 14695 Facultad de Filosofia y Letras of the Universidad Nacional de Cuy

RESUMEN Palabras c laves: obsidiana -arqueología -estudios quí-micos -Mendoza -Chile central. ABSTRACT

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We studied the organization of mobility of hunter-gatherers groups of northwestern Patagonia (Argentina) from an interdisciplinary perspective. We combined geochemical and technological characterization of obsidian assemblages from surface and stratigraphic contexts spanning the Holocene, and a preliminary geoarchaeological study of the sources. The goals were to assess the provenance, mode of supply, use, and discard of obsidian artifacts on the basis of information on the structure of the two main regional sources: Cerro Huenul, located in the lowlands, and Laguna del Maule, located in the Andean highlands. We conducted geoarchaeological field sampling at different altitudes of the Barrancas River fluvial deposits to study the geomorphic impact on the secondary structure of the highland source. Preliminary geoarcheological results allow extending the area of availability up to 90 km towards the lowlands from the outcrops.In addition, we performed non-destructive XRF analyses on 266 lithic artifacts, which were placed along a continuum of reduction. 89% of the artifacts corresponded to the local Cerro Huenul source, while 11% to Laguna del Maule. While the artifacts made on Cerro Huenul obsidian were represented by the full reduction sequence, those from

Northwestern Patagonia is located in a tectonically active part of the southern Andes (Argentina), which has facilitated the formation of obsidian, including pyroclastic deposits that have been affected by geomorphic processes, resulting in a complex obsidian landscape. To date, the geomorphic relocation of obsidian in the landscape has not been a focus of systematic research, and this hampers our understanding of prehistoric human mobility. We present an updated assessment of the regional availability of different obsidian types based on results from our research program, which combines geoarchaeological survey and geochemical characterization to understand the properties and distribution of obsidian. This robust “source‐scape” provides the foundation for reconstructing patterns of lithic provisioning and discard. Our results suggest that interpretations of obsidian availability across the landscape should be more nuanced than is typically acknowledged. Based on our improved “source‐scape,” we discuss the patterns observed in an archaeological X‐ray fluorescence database. When compared with the geoarchaeological reconstruction of obsidian availability, the archaeological record conforms to a distance‐decay pattern. Contrary to previous interpretations, we suggest that the distribution of obsidian types is not isomorphic with human home ranges. This geoarchaeological research program provides a basis for integrating the archaeological record of different Andean regions.