X-ray fluorescence in Member States: Argentina. Characterization of black vulcanites coming from Rincon Chico 2 site, Neuquen, Argentina, by using X-ray fluorescence spectrometry

Full text: The investigation of prehistoric hunter-gatherers archaeological sites in the Limay river basin (provinces of Neuquen and Rio Negro) raised different questions concerning the lithic technology. In Rincon Chico 2, a site located on the margin of the Limay river in the Neuquen province and nowadays submerged by the Piedra del Aguila reservoir, many tools and debitage made in black volcanic rock has been found. The identification of this raw material can give information about possible sources of provenance. The rocks were classified macroscopically either as basalt (with coarse grains) or dacite (with fine grains) However, in several cases, a dual behaviour was observed in the fracture zone: the texture was coarse on the surface and very fine, sometimes almost vitreous, in the interior. Following this observation, it was decided to introduce a new more general category called 'black vulcanites'. Looking for the origin and more precise identification of this raw material, artifactual samples and a set of black vulcanite fragments coming from Paso Limay, a dacite source located 50 km from the archaeological site, were characterized by X-ray fluorescence spectrometry using a Philips Minipal energy dispersive system. Samples were analysed as loose powder. Statistical analysis reveals greater variability between artefact samples than between the samples from the source itself. This discrepancy is more evident if Fe, Ti and Zn are used as markers. These results suggests that the quarry at Paso Limay was not the main source of provenance of the black vulcanites utilized by the hunter-gatherers occupying Rincon Chico. (author)