Tracking ancient people movements in the Sierras Pampeanas 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 wherethe Precambrian crystalline basement outcrops, including South Africa, Northern Europe, North Americaand large areas of South America. However, little effort has been made to try to characterize its chemicalcomposition to help understand either mobility strategies or exchange networks.We report here the results of a preliminary methodological approach comparing the chemicalcharacterization of quartz from archaeological sites (quarries and residential types) and geological sourcesthrough 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 residentialarchaeological sites from the Ongamira valley (a mountainous region of Central Argentina) wasundertaken in this work. The archaeological samples came from layers radiocarbon-dated to the LateHolocene (between ca. 3600 BP to 3000 BP) and are related to nomadic hunter-gatherer societies wherethe use of quartz for technology was predominant (representing more than 90 percent of the tools anddebris in each archaeological site).As a result of the comparison it was possible to establish positive or negative relationships between someof the quartz samples from the residential locus and the geological sources. Some results showed that thenearest quarries to the residential sites were not used at the residential camp. On the other hand, it wasalso possible to establish that non-local quartz outcrops located far away from the Ongamira valley werenot present at any of the Ongamira sites. This shows us that rock procurement was oriented to theselective use of local raw material and therefore a low-range mobility strategy. Finally, it may be relatedto better local environmental conditions in the Late Holocene, when people did not need to travel so farfor other resources or purposes