Martin Giesso

Analysis of 519 obsidian artifacts (pebbles, debitage, cores and small bifaces) by nondestructive X-ray fluorescence from forests and steppes of southern Lanín National Park in the northern Patagonian Andean region, from Lácar (chemical group QU/AP), Lolog (CP-LL 1), Filo Hua-Hum (FHH), Paillakura (Pk, former unknown 1 group), Meliquina (MQ, former unknown group 2) and Yuco (YC) sources. Neutron activation analysis was applied to 29 of the artifacts. We identified for the first time the presence of obsidian from distant Covunco (PC1) in the center of Neuquén. This paper is the first English language publication of our ongoing, ten-year-long research. In accordance with previous work, but using other analytical techniques, the most frequently used sources during the late Holocene remain CP/LL 1 and Pk, here we add YC, mainly by the incorporation of new sites recently surveyed in the islands and the coast of Lake Lácar, next to its source. Another result consistent with previous work is the absence of obsidian from Mendoza and Chilean sources; therefore, we suggest these obsidians circulate just to the east and northeast, allowing us to discuss issues of human territoriality during the Late Holocene.

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

ABSTRACT The importance of obsidian from the northern Patagonian source at Las Cargas is reflected in its early use (�8000 years B.P.) and extensive geographic diffusion but is nonetheless surprising in light of the source’s high altitude (located in the Andes Cordillera), which makes it both difficult to access under ideal conditions and inaccessible for much of the year. Prehistoric use of the Las Cargas source can inform us about mobility, subsistence choices, economics of stone consumption, trade, and territoriality. Here we present the results of various lines of evidence (surface survey, X-ray fluorescence and instrumental neutron activation analyses, artifact morphometry, and obsidian hydration dating) used to characterize obsidian from Las Cargas and its prehistoric use during the Holocene. Results indicate that Las Cargas obsidian occurs at the source as blocks and nodules, which are chemically homogeneous and of variable quality. Use of the source was nearly continuous through time, and the primary knapping activities performed there were the production of blanks and preparation of cores

The importance of obsidian from the northern Patagonian source at Las Cargas is reflected in its early use (8000 years B.P.) and extensive geographic diffusion but is nonetheless surprising in light of the source’s high altitude (located
in the Andes Cordillera), which makes it both difficult to access under ideal conditions and inaccessible for much of the year. Prehistoric use of the Las Cargas source can inform us about mobility, subsistence choices, economics of stone consumption, trade, and territoriality. Here we present the results of
various lines of evidence (surface survey, X-ray fluorescence and instrumental neutron activation analyses, artifact morphometry, and obsidian hydration dating) used to characterize obsidian from Las Cargas and its prehistoric use
during the Holocene. Results indicate that Las Cargas obsidian occurs at the source as blocks and nodules, which are chemically homogeneous and of variable quality. Use of the source was nearly continuous through time, and the primary knapping activities performed there were the production of blanks and preparation of cores.

Recent research in the Andes indicates that obsidian was procured and distributed over long distances since the Late Pleistocene and until the Spanish conquest. In this research we used XRF at the Missouri University Research Reactor to determine the number of sources present in a collection of Intihuasi cave obsidian, and its potential provenience. Intihuasi is one of the archaeological sites with obsidian that is outside of the Andean area, and at least 300 km from the nearest source. These materials are at the Museo de Antropología of the Universidad Nacional de Córdoba. The location of one of these sources is northern Neuquén. They are made some suggestions in relation to long distance interactions.

Trace element analysis has been performed on 911 samples from 106 archaeological sites and more than 100 samples
from six sources. The samples come from archaeological sites located in all environments within a large area located
between 32º and 37º south and 67º and 72º west, and in a chronological range of 9000 to 300 years BP. Analyses were
performed to determine the spatial distribution of sources and to investigate the potential of these data to test models of
mobility and exchange proposed for different regions in that area. Three different X-ray fluorescence (XRF)
spectrometers were used: two energy dispersive and one wavelength dispersive. This paper discusses some problems of
interpretation of archaeological and geological records related to the application of different methods and equipment.
This experience shows the need to improve the geochemical sampling of sources and to confront different methods of
analysis and calibration. The results provide an adequate resolution for discriminating the use of different sources
throughout the Holocene, indicating variable spatial and temporal distributions. The general trend shows a preferential
use of the sources located in the mountainous regions. Las Cargas source, used since the early Holocene (ca. 9000-8000
BP), together with Laguna del Maule source, were the most important sources in the entire area (including eastern and
western slopes of the Andes).

A B S T R A C T 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 geoarchaeolo-gical 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 geoarchaeological 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 Laguna del Maule are only represented by advanced stages. We integrate these results with information on the frequencies of projectile points, ceramics, and rock-art motifs for the two main archaeological sites in the region: Cueva Huenul 1 and Cueva Yagui. These proxies indicate that the sites have different place use histories, providing a scheme for the analysis of human use of the regional landscape.