Search

The natural volcanic glass obsidian is one of the classical objects of archaeometric analyses. Reliable provenancing by means of the highly specific chemical composition, the “chemical fingerprint”, can provide information about trading routes, extension of territory, long-distance contacts and the mobility of prehistoric people. Since the pioneer work of Cann and Renfrew in 1964 [1] various analytical methods have been employed on obsidian samples in order to locate their provenance. The existing data already offers important knowledge about long-distance interactions between prehistoric human populations. However, most applied techniques just show a small part of the element spectrum. Latest studies showed that published results gained by different analytical methods are not consistent due to systematic errors [2-3]. Therefore, the application of three complementary analytical techniques on the same set of raw material samples allows both a better characterization of obsidian sources and a comparison and validation of analytical results. The aim of this multi-methodical approach is to apply in particular: • Ion Beam Analysis (IBA) comprising of Particle Induced X-ray Emission (PIXE) and Particle Induced Gamma-ray Emission (PIGE), • Instrumental Neutron Activation Analysis (INAA), • Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) to detect a maximum element spectrum and to compare element concentrations determined with at least two analytical techniques. This approach should check the accuracy and reliability of analytical results and should show a maximum of compositional differences between European obsidian sources to reveal the most characteristic “chemical fingerprint” composed of more than 40 elements. These investigations are part of a new multi-methodical analytical database called the “Obsidian Least Destructive Analysis Provenancing System” (OLDAPS). This novel scientific approach for provenancing obsidian artefacts found in archaeological contexts contributes to both conservation and prehistoric research by ensuring a minimum of destruction to gain a maximum of information. Besides, it enables to assess analytical accuracies of our archaeometric elemental analyses. For this study, IBA, INAA and LA-ICP-MS measurements have been applied to the most relevant obsidian sources in central and southern Europe. IBA studies have been carried out using the external 4 MeV proton beam of the 6 MV Tandem accelerator of the Ion Beam Centre of HZDR. INAA investigations have been performed in the TRIGA Mark II 250 kW research reactor of the Atominstitut in Vienna. LA-ICP-MS measurements have been taken with the Thermo Element 2 ICP-MS coupled to an ArF gas Excimer laser system at the Aberystwyth University. [1] J.R. Cann, C. Renfrew, Proc. Prehist. Soc. 30, (1964) 111-131. [2] R.G.V. Hancock, T. Carter, J. Archaeol. Sci. 37, (2010) 243–250. [3] G. Poupeau et al., J. Archaeol. Sci. 37, (2010) 2705-2720.

Obsidian ist ein natürliches, vulkanisches Glas, welches bei geeigneter Bearbeitung die Herstellung von sehr scharfen Werkzeugen und Waffen ermöglicht. Auf Grund dieser Eigenschaft war Obsidian einer der begehrtesten und daher weitest verbreiteten Rohstoffe in prähistorischen Kulturkreisen. Die Herkunftsbestimmung von Obsidianen, liefert somit Kenntnisse über ur- und frühgeschichtliche Handelsbeziehungen. Zur Charakterisierung von Obsidianen wird der sogenannte „chemische Fingerprint“ herangezogen, welcher die Bestimmung signifikanter Unterschiede in den Elementzusammensetzungen ermöglicht. Seit der Pionierarbeit von Cann und Renfrew 1964 [1] wurden zahlreiche Analysen mit den unterschiedlichsten Methoden durchgeführt. Die existierende Datenbasis hat bereits wichtige Erkenntnisse über die Verbreitung des Obsidians erbracht, wobei in den häufigsten Fällen nur Teile des Elementspektrums bestimmt wurden. Neueste Untersuchungen haben aufgezeigt, dass bei publizierten Herkunftsbestimmungen mit unterschiedlichen Methoden aufgrund systematischer Fehler nicht direkt vergleichbare Daten produziert wurden [2, 3]. Eine kombinierte Anwendung derAnalysemethoden: • Instrumentelle Neutronenaktivierungsanalyse (INAA), durchgeführt am TRIGA Mk II Forschungsreaktor des Atominstituts der TU Wien • Kombinierte externe Ionenstrahlanalytik: Particle Induced X-ray Emission (PIXE) und Particle Induced Gamma-ray Emission (PIGE), ausgeführt am 6 MV Tandembeschleuniger des HZDR • Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry (LA-ICP-MS) Messungen, durchgeführt an der Aberystwyth University, Wales, UK auf denselben Satz von Obsidianproben ermöglicht einerseits die Bestimmung eines umfangreichen und aussagekräftigen Elementspektrums, andererseits einen direkten Vergleich der Reproduzierbarkeit und Richtigkeit der Analysenwerte. Mit Hilfe dieser Analyseverfahren wurde eine methodenübergreifenden Datensammlung von Obsidian-vorkommen aus dem europäischen Raum erstellt. Diese Vorgehensweise liefert ein größtmögliches Elementspektrum aus mehr als 40 Elementen und enthüllt die signifikantesten Elemente zur Obsidiancharakterisierung (siehe Abb. 1). Abbildung 1: Elementspektrum von Obsidian aus Demenegakion und Agia Nychia (Melos, Griechenland). Die Kombination von INAA-, PIXE & PIGE- und LA-ICP-MS-Daten liefert einen maximalen „chemischen Fingerprint“ von 41 Elementen. Die Normierung auf eine interne Obsidian-Referenzprobe aus Hrafntinnuhryggur (Island) ermöglicht eine eindeutige Unterscheidung der beiden Vorkommen in den Konzentrationen von Ca, Ti, Sc, Fe und Co. Die unmittelbare Vergleichbarkeit der Resultate unter Berücksichtigung der jeweiligen Messunsicherheit ist essentiell für die Entscheidung, welche analytische Methode auf weitere archäologische Artefakte angewendet werden soll, um bei möglichst geringem Eingriff die aussagekräftigsten Informationen zu liefern. [1] J.R. Cann, C. Renfrew, Proc. Prehist. Soc. 30 (1964) 111-132. [2] R.G.V. Hancock, T. Carter, J. Archaeol. Sci. 37 (2010) 243–250. [3] G. Poupeau et al., J. Archaeol. Sci. 37 (2010) 2705-2720.

The two obsidian sources from the island of Melos (Greece), Agia Nychia and Demenegakion, are chemically characterized by three complementary analytical techniques. Ion beam analysis (IBA) comprising of particle induced X-ray emission (PIXE) and particle induced gamma-ray emission (PIGE), neutron activation analysis (NAA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) are applied to the same set of geological obsidian samples. The combination of methods allows a more complete characterisation of obsidian sources and reveals a highly specific chemical composition, the so-called chemical fingerprint. This multi-methodical approach checks also the self-consistency of the analytical results and shows the most reliable and characteristic key elements Co and Sc, but also Fe, Ca and Ti of Melos obsidian deposits. NAA contributes the largest number of reliable elements to the most unambiguous chemical fingerprint comprising in total of 41 elements. Therefore, NAA is the most suitable analytical method for a clear identification of Melos obsidian deposits. Moreover, the accuracy of methods is demonstrated by the excellent correspondences (calculated correlation coefficient R2=1.00 for IBA and NAA, R2=0.99 for LA-ICP-MS) between determined analytical results obained by IBA, NAA and LA-ICP-MS and certified values of the reference glass BAM-S005B.

The natural volcanic glass obsidian is one of the classical objects of archaeometrical analyses. Reliable provenancing by means of its highly specific chemical composition, the “chemical fingerprint”, can provide information about economy, policy and the social system of ancient societies. Although Mediterranean obsidian have mainly been the focus of characterization since the pioneer work of Cann and Renfrew (1964), provenancing of Central and Eastern Europe obsidian sources attracts increasing attention in the past decades. Fingerprinting of Hungarian and Slovakian obsidian sources is of great interest especially for Central European sites where obsidian has been widely used (Williams-Thorpe et al., 1984, Kasztovszky et al., 2008, Biró, 2009). The application of three complementary analytical techniques on the same set of raw material samples allows both, a more complete characterization of obsidian sources and a comparison of analytical results. The aim of this multi-methodical approach is to apply three different analytical methods, in particular: • Instrumental Neutron Activation Analysis (INAA), • Ion Beam Analysis (IBA) comprising of Particle Induced X-ray Emission (PIXE) and Particle Induced Gamma-ray Emission (PIGE) • Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) to detect a maximum element spectrum and to compare element concentrations determined with at least two analytical techniques. This way a check of self-consistency of analytical results is possible. Furthermore, it allows the identification of a maximum of compositional differences between Hungarian and Slovakian sources by revealing the most characteristic “chemical fingerprint” composed of more than 40 elements. For this study, NAA, IBA and LA-ICP-MS measurements are scheduled to be applied to 25 raw material samples from sources from Hungary and Slovakia in cooperation with the Natural History Museum Vienna (Hammer, V. and Seemann, R., Department of Mineralogy and Petrography) and the Vienna Lithothek (Trnka, G., Department of Prehistoric and Protohistoric Archaeology). Up to now, IBA studies have already been carried out using the external 4 MeV proton beam of the 6 MV Tandem accelerator of the Ion Beam Centre of Helmholtz-Zentrum Dresden-Rossendorf. Further NAA investigations will be performed at the TRIGA Mark II 250 kW research reactor of the Atominstitut in Vienna. LA-ICP-MS measurements will be conducted using the Thermo Element 2 ICP-MS coupled to an ArF gas Excimer laser system at the Aberystwyth University. CANN, J.R. AND RENFREW, C, 1964. The characterization of obsidian and its application to the Mediterranean Region. Proceedings of the Prehistoric Society 30, 111-131. WILLIAMS-THORPE, O., WARREN, S.E. and NANDRIS, J.G., 1984. The distribution and provenance of archaeological obsidian in central and eastern Europe. Journal of Archaeological Science 11, 183-212. KASZTOVSZKY, Z., BIRÓ, K., MARKÓ, A. and DOBOSI, V., 2008. Prompt gamma activation analysis for non-destructive characterization of chipped stone tools and raw materials. Journal of Radioanalytical and Nuclear Chemistry 278, 293-298. BIRÓ, K.T., 2009. Sourcing Raw Materials for Chipped Stone Artifacts: The State-of-the-Art in Hungary and the Carpathian Basin. In: Adams, B. and Blades, B.S. (Eds.) Lithic Materials and Paleolithic Societies (eds B. Adams and B. S. Blades), Wiley & Blackwell, 47-53.