Tracking ancient people movements in the Southern Pampean Hills of Argentina by XRF, XRD and SEM on quartz lithic technology: a preliminary report

Abstract

Quartz-based hunter-gatherer lithic technology is present around the world. It occurs particularly where the Precambrian crystalline basement outcrops, including South Africa, Northern Europe, North America and large areas of South America. However, little effort has been made to try to characterize its chemical composition to help understand either mobility strategies or exchange networks. We report here the results of a preliminary methodological approach comparing the chemical characterization of quartz from archaeological sites (quarries and residential types) and geological sources through different techniques: X-Ray Fluorescence, X-Ray Diffraction, SEM and EPMA analyses. The detection of trace elements from quartz outcrops and its comparison with artifacts from residential archaeological sites from the Ongamira valley (a mountainous region of Central Argentina) was undertaken in this work. The archaeological samples came from layers radiocarbon-dated to the Late Holocene (between ca. 3600 BP to 3000 BP) and are related to nomadic hunter-gatherer societies where the use of quartz for technology was predominant (representing more than 90 percent of the tools and debris in each archaeological site). As a result of the comparison, it was possible to establish positive or negative relationships between some of the quartz samples from the residential locus and the geological sources. Some results showed that the nearest quarries to the residential sites were not used at the residential camp. On the other hand, it was also possible to establish that non-local quartz outcrops located far away from the Ongamira valley were not present at any of the Ongamira sites. This shows us that rock procurement was oriented to the selective use of local raw material and therefore a low-range mobility strategy. Finally, it may be related to better local environmental conditions in the Late Holocene, when people did not need to travel so far for other resources or purposes.