Characterization of obsidian samples from northern and south central Chile using X-ray fluorescence analyses

Abstract

This work is apart of a project to characterize the sources and provenance of obsidians found in archaeological sites in Chile. The aim of the project is to characterize the different sources used in the past and study its distribution. In the present work obsidian samples from different Chilean geological regions, located in South Central Chile (Laguna del Maule/volcanic area, sources of Las Coloradas and La Plata), "Radal 7 Tazas" and the North of Chile (Copiapo 1, volcano) were analyzed, as well as obsidian artifacts from "site 25-Las Estacas ", Quebrada de Jorquera (Copiapo, Northern Chile) by means of X-ray fluorescence, using radioactive sources. The analysis was performed using Cd-109 and Am-241 annular excitation sources and X-ray fluorescence system. This allowed the determination of Fe, Cu, Rb, St. Y. Zr, and Ba concentrations on samples of ground obsidian from the aforementioned sites. The measured Rb, Sr, and Zr concentrations were used to construct discriminant diagrams, which clearly showed Clustering of the samples from the different sources, and the association of the archaeological obsidian sample to the Copiapo Volcano source, which is geographically close to the site.