Bernard Gratuze

Middle Palaeolithic and Neolithic Occupations around Mundafan Palaeolake, Saudi Arabia: Implications for Climate Change and Human Dispersals

The Arabian Peninsula is a key region for understanding climate change and human occupation history in a marginal environment. The Mundafan palaeolake is situated in southern Saudi Arabia, in the Rub’ al-Khali (the ‘Empty Quarter’), the world’s largest sand desert. Here we report the first discoveries of Middle Palaeolithic and Neolithic archaeological sites in association with the palaeolake. We associate the human occupations with new geochronological data, and suggest the archaeological sites date to the wet periods of Marine Isotope Stage 5 and the Early Holocene. The archaeological sites indicate that humans repeatedly penetrated the ameliorated environments of the Rub’ al-Khali. The sites probably represent short-term occupations, with the Neolithic sites focused on hunting, as indicated by points and weaponry. Middle Palaeolithic assemblages at Mundafan support a lacustrine adaptive focus in Arabia. Provenancing of obsidian artifacts indicates that Neolithic groups at Mundafan had a wide wandering range, with transport of artifacts from distant sources.

Application of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for the investigation of ancient silver coins

The main characteristic of ancient silver coins lies in the existence of silver surface enrichment that often covers them. The non-destructive methods used so far to analyze these precious objects do not take into account this phenomenon, whose importance cannot be estimated without destruction of the coins. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), as a spot method particularly convenient for the analysis of solid samples, has been applied to ancient silver coins for the first time. This paper presents the LA-ICP-MS analytical protocol developed to characterize these objects, whose main innovation lies in the realization of concentration depth profiles for the major elements (Ag and Cu) and five main minor elements (Zn, Sn, Au, Pb, Bi). The concentrations determined in this way reflect the composition of the alloy that has not been disturbed by surface enrichment phenomena. Minor and trace elements are determined by average single spot analysis. The optimal experimental conditions have been defined by studying both modern alloys and ancient coins. The reliability of the matrix-matched standards and the reproducibility of the micro-samplings have been checked and the relevance of the protocol developed then verified by a comparison of the results obtained by LA-ICP-MS and fast neutron activation analysis.

Sembiran and Pacung on the north coast of Bali: a strategic crossroads for early trans-Asiatic exchange

Abstract Studies of trade routes across Southeast Asia in prehistory have hitherto focused largely on archaeological evidence from Mainland Southeast Asia, particularly the Thai Peninsula and Vietnam. The role of Indonesia and Island Southeast Asia in these networks has been poorly understood, owing to the paucity of evidence from this region. Recent research has begun to fill this void. New excavations at Sembiran and Pacung on the northern coast of Bali have produced new, direct AMS dates from burials, and analytical data from cultural materials including pottery, glass, bronze, gold andsemi-precious stone, as well as evidence of local bronze-casting. This suggests strong links with the Indian subcontinent and Mainland Southeast Asia from the late first millennium BC, some 200 years earlier than previously thought.

Comprehensive Chemical Characterisation of Byzantine Glass Weights

The understanding of the glass trade in the first millennium CE relies on the characterisation of well-dated compositional groups and the identification of their primary production sites. 275 Byzantine glass weights from the British Museum and the Bibliothèque nationale de France dating to the sixth and seventh century were analysed by LA-ICP-MS. Multivariate statistical and graphical data analysis discriminated between six main primary glass types. Primary glass sources were differentiated based on multi-dimensional comparison of silica-derived elements (MgO, Al2O3, CaO, TiO2, Fe2O3, ZrO2) and components associated with the alkali source (Li2O, B2O3). Along with Egyptian and Levantine origins of the glassmaking sands, variations in the natron source possibly point to the exploitation of two different natron deposits. Differences in strontium to calcium ratios revealed variations in the carbonate fractions in the sand. At least two cobalt sources were employed as colouring agents, one of which shows strong correlations with nickel, indicating a specific post-Roman cobalt source. Typological evidence identified chronological developments in the use of the different glass groups. Throughout the sixth century, Byzantine glass weights were predominately produced from two glasses that are probably of an Egyptian origin (Foy-2 and Foy-2 high Fe). Towards the second half of the sixth century a new but related plant-ash glass type emerged (Magby). Levantine I was likewise found among the late sixth- to early seventh-century samples. The use of different dies for the same batch testifies to large-scale, centralised production of the weights, while the same die used for different primary production groups demonstrates the co-existence of alternative sources of supply. Given the comprehensive design of our study, these results can be extrapolated to the wider early Byzantine glass industry and its changes at large.

Glass Characterization Using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Methods

The accurate determination of archaeological glass sample composition is challenging due to possible heterogeneity and post-production chemical alteration. Here, depth profiling using the time resolved signal generated by LA-ICP-MS (DP-LA-ICP-MS) is applied to two case studies. The first study concerns corroded Late Bronze Age glass beads. While many varieties of ancient glass beads are corrosion resistant, some recipes are particularly impacted by devitrification, and depth profiling allows for analysis of un-corroded material reflecting original glass composition. In the second case study on a seventeenth century composite glass vessel, depth profiling allowed for measurement of composite layers including a thin ruby gold glass layer and white opaque glass filigree embedded in colorless lead glass. The minimal destructiveness of this technique combined with other advantages of LA-ICP-MS—the large number of elements that can be measured and low detection limits—make this technique ideal for analysis of many kinds of compositionally complex glass objects.

Recent Advances in Laser Ablation ICP-MS for Archaeology

This book explores different aspects of LA-ICP-MS (laser ablation-inductively coupled plasma-mass spectrometry). It presents a large array of new analytical protocols for elemental or isotope analysis. LA-ICP-MS is a powerful tool that combines a sampling device able to remove very small quantities of material without leaving visible damage at the surface of an object. Furthermore, it functions as a sensitive analytical instrument that measures, within a few seconds, a wide range of isotopes in inorganic samples. Determining the elemental or the isotopic composition of ancient material is essential to address questions related to ancient technology or provenance and therefore aids archaeologists in reconstructing exchange networks for goods, people and ideas. Recent improvements of LA-ICP-MS have opened new avenues of research that are explored in this volume.

The geochemical characterization of two long distance chert tracers by ED-XRF and LA-ICP-MS. Implications for Magdalenian human mobility in the Pyrenees (SW Europe)

ABSTRACT We geochemically characterize two chert formations outcropping in the Pyrenees and presenting similar characteristics at the visual and microscopic scale: The Montgaillard flysch cherts and the Montsaunès cherts. Cherts presenting identical textural and micropalaeontological features as both types have been found in several Magdalenian Pyrenean sites. We are face to a long distance chert type whose geochemical characterization is essential for knowing where the tracer comes from. Analyses have been done using Energy-dispersive X-ray fluorescence (ED-XRF) and laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS). Results show that despite obtaining similar data concerning major and minor elements, differences have been observed regarding trace elements. The establishment of differences between both formations at the geochemical level has allowed specifying the origin of this chert type recovered at the Magdalenian levels of Parco Cave (Alòs de Balaguer, Spain). Results demonstrate long lithic raw material circulation and thus, human mobility in the Pyrenees during the Upper Palaeolithic.

Characterization of Slag Inclusions in Iron Objects

Tracing the origins of iron artifacts generates great interest in iron metallurgy. Chemical analysis of non-metallic slag inclusion (SI) entrapped in iron produced in bloomery furnaces is an efficient mean for provenance studies as, within their composition, SI do not only carry the conditions of production but also the chemical signature of the iron ore initially used. The analytical protocol is a three stage process: (a) metallographic identification and selection of SI, (b) characterization of their main component using SEM-EDX, (c) traces element determination using LA-ICP-MS. LA-ICP-MS analysis allows to quantify up to 39 trace elements in the fayalitic-rich matrix of SI with detection limits at the ppm level. Compositional ratios are then compared with one another and to the chemical signature of previously analysed regions of production. The methodology was applied on iron armatures from the cathedral of Bourges to study their fabrication, their installation in the building and their provenance. Results obtained allow a better understanding of the role of these armatures and the supply of this construction site.

The trade of glass beads in early medieval Illyricum: towards an Islamic monopoly

The trade of glass beads has long been assumed to have been under Islamic dominance during the early centuries following the Arab conquest of the Middle East, judged by the prevalence of Islamic beads in the archaeological contexts from Viking Scandinavia to medieval Morocco. This paper explores the impact of the Byzantine-Slavic transition on the use and by extension trade of glass beads in the Balkans from the seventh to the ninth century CE. A series of 48 glass beads and 4 vessel fragments from two excavated sites in modern day Albania have been analysed morphologically, technologically and chemically by LA-ICP-MS. The seventh-century beads from Lezha have typological parallels among central European assemblages and are made from recycled natron-type glass. The presence of a high lead-iron-natron variant is of particular interest as it potentially reflects a regional production. The ninth-century beads from Komani are made from soda-rich plant ash glass from the eastern Mediterranean and Mesopotamia and correspond to an Islamic typology. The chronological and geographical differences are reflected in the distinctive cobalt sources used for the two groups. While the beads from Lezha are coloured with a cobalt not correlated with any particular element, the cobalt source of the Komani samples is associated with zinc, typical of Islamic glass making. It thus appears that the supply of beads during the seventh century when the Balkans were under Slavic occupation relied on regional production and recycled material, and that a long-distance trade with the eastern Mediterranean was revived following the Byzantine re-conquest of the south-eastern Adriatic in the ninth century. Intriguingly, the Albanian finds confirm the Islamic control of the production and trade of glass beads during this period and highlight the mediatory role of the Byzantine Empire.

Reconsidering prehistoric chert catchment sources: new data from the Central Pyrenees (Western Europe)

In the framework of a postdoctoral project to geochemically characterise Pyrenean cherts, a new marine chert outcrop in the Central Pyrenees has been defined. This new discovery, called the Buala outcrop, and its flysch chert type, provide new information about marine chert sources in the Pyrenean chain, leading us to reconsider prehistoric chert procurement in this area. Until now, two geological formations from the Central Pyrenees were considered as potential sources for a type of marine chert usually appearing in the Magdalenian record of several Pyrenean sites: Montgaillard flysch cherts and Montsaunès cherts. With both formations presenting similar characteristics, it was only through the use of geochemical methods that differences were recently established as reported by Sánchez de la Torre et al. (STAR 3:15–37, 2017b). This paper presents the new marine flysch chert outcrop of Buala. The visual, micropalaeontological and geochemical characterisation of this chert has permitted the definition of a new potential source for this marine chert type, which is common in several Palaeolithic sites in the Pyrenees, as Cova del Parco (Alòs de Balaguer, Spain), Forcas I Shelter (Graus, Spain), Montlleó open-air-site (Prats i Sansor, Spain), or Caune de Belvis (Belvis, France) (Sánchez de la Torre 2015). Geochemical characterisation of the three potential sources was carried out using energy-dispersive X-ray fluorescence (ED-XRF) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Results show that Buala flysch cherts are clearly different from the previously known chert types in terms of major, minor, and trace elements.