Application of Laser Ablation- ICP-MS for characterization of obsidian fragments from peri-Tyrrhenian area

This paper presents the results of a geochemical study on obsidian fragments by Inductively Coupled Plasma Mass Spectrometry associatedwith Laser Ablation (LA-ICP-MS). This analytical method, almost non-destructive, has proven to be a powerful tool for ‘‘in situ’’ determinationof trace elements, and is very useful in characterizing and determining the provenance of obsidian fragments of archeological interest. Its major advantage is that 29 trace and rare earth elements can be analysed in a very short time, without any sample manipulation.Analyses were carried out on 27 representative obsidian samples, collected from the main geological outcrops of Sardinia and the minorislands of Lipari, Pantelleria and Palmarola, in the peri-Tyrrhenian area, and on eight obsidian fragments recovered from three different Italianarcheological sites of Neolithic age. The geological samples show variable trace element and REE compositions, and differences in Cs, Y, Zr,Nb, Ba, La, Nd, Ho, Er and Yb were great enough to allow the various source areas to be distinguished. The fragments fall into seven compositionalgroups. Three, which are homogeneous but clearly distinct from each another, include the Lipari, Palmarola and Pantelleria samples. Theother four groups refer to the obsidian of Monte Arci in Sardinia, already known in the literature as SA, SB1, SB2 and SC. LA-ICP-MS establishedthe definite origin and source areas of the artefacts.Analytical results indicate that, for obsidian samples from the peri-Tyrrhenian area, significant geochemical differences exist in their trace and REE compositions, which identify their source areas and establish their provenance for archeometric purposes.