Geochemical Variability in the Paredón Obsidian Source,Puebla and Hidalgo,Mexico: A Preliminary Assessment and Inter‐Laboratory Comparison

Chemical characterization reveals intra‐source variation in obsidian from the Paredón source area in Puebla and Hidalgo, Mexico. Two chemical sub‐sources of obsidian from Paredón are spatially discrete and cannot be distinguished by visual characteristics. To facilitate future investigations of the prehistoric exploitation of these sub‐sources, an inter‐laboratory comparison of elemental concentrations is presented based on neutron activation analysis and several XRF instruments.     

Isothermal Time‐Series Determination of the Rate of Diffusion of Water in Pachuca Obsidian*

Friedman and Smith's (1960) article introducing an exciting, potentially precise and inexpensive method of dating obsidian artefacts has thus far failed to reach its potential. Numerous efforts to refine, improve and even redevelop the method since that time have similarly failed to achieve the original promise. Only within the last eight years have significant improvements been made, due to both improved analytical techniques and a better understanding of the hydration process. However, most of our mechanistic understanding of the interaction of water with rhyolitic glass is based on experiments performed on melts and glasses at temperatures above their glass transitions, conditions inappropriate for investigation of near‐surface environmental conditions. Unfortunately, studies detailing the temporal evolution of the diffusion profile at low temperatures are rare, and few useful data are available on the low‐temperature diffusive hydration of silicate glasses. This paper presents data on the experimental hydration of obsidian from the Pachuca source (a.k.a. Sierra de las Navajas, Basin of Mexico) at 75°C for times ranging from 3 to 562 days, and compares these results with data for samples obtained from a stratigraphic excavation of the Chalco site in the Basin of Mexico. Samples have been analysed using secondary ion mass spectrometry (SIMS) to provide concentration/depth data. While 75°C is still significantly above the temperatures at which archaeological obsidians hydrate, it is well below the glass transition temperature (approx. 400°C) and thus processes are likely to be similar to those that occur in nature, but fast enough to be observed over a laboratory timescale. The results demonstrate that a simple square‐root‐of‐time model of the evolution of the diffusion profile is not adequate to describe the diffusion process, as measured diffusion profiles exhibit the effects of concentration‐ and time‐dependent, non‐Fickian diffusion. With progressive hydration, characteristic diffusion coefficients first decrease, then increase with time. Surface concentration increases with time, but an intermediate plateau is observed in its time evolution that is consistent with results obtained from the suite of Chalco samples. Both of these effects have been observed during diffusion in glassy polymer systems and are associated with the build‐up and relaxation of self‐stress caused by the influx of diffusing material.     

Long-distance provenance for obsidian artifacts of Mesoamerica Preclassic and Early Classic periods found in the Los Naranjos Archaeological Park (Honduras)

Los Naranjos is one of the most important pre-Columbian human settlements of Honduras related to the south-easternmost border of the Mayan civilization. Although the archaeological site mostly spans from 850 BC to 1250 AD, the present obsidian study was only focused on the Preclassic and Early Classic periods (Jaral, 800–400 BC and Edén, 400 BC–550 AD) where undamaged blades and/or retouched obsidian flakes are rare. In this way, the INAA analyses of 17 obsidian samples, compared with major-trace elements data of Honduran and Guatemalan obsidian sources, are mostly representative of waste flakes. Lithic artifacts of Los Naranjos such as sandstones, basalts, and quartzites come from local geological outcrops; whereas, obsidian provenance has to be searched from sources which are located within a radius up to 300 km far away. San Luis, La Esperanza, and Güinope obsidian sources are located in Honduras while the three most exploited Highland Guatemalan obsidian outcrops, which have been dominating long-distance trade in the Maya area mostly for the Classic-Postclassic periods, are San Martin de Jilotepeque, El Chayal, and Ixtepeque. An Ixtepeque provenance, for all the investigated obsidian samples of Preclassic and Early Classic periods found in the Los Naranjos Archaeological Park, was established, thus emphasizing a long-distance source (180 km). This also confirms that Ixtepeque represents the most important provenance of the obsidian artifacts found in archaeological sites of Western and Central-Western Honduras. The possible role played by some of the most important rivers of Guatemala and Honduras as waterway networks of transport was finally pointed out. New INAA chemical data from the Honduran obsidian source of La Esperanza (“Los Hoyos”, 4 samples) are also reported in this paper.     

The use of SEM-EDS,PIXE and EDXRF for obsidian provenance studies in the Near East: a case study from Neolithic Çatalhöyük (central Anatolia)

In this paper we evaluate the relative analytical capabilities of SEM-EDS, PIXE and EDXRF for characterizing archaeologically significant Anatolian obsidians on the basis of their elemental compositions. The study involves 54 geological samples from various sources, together with an archaeological case study involving 100 artifacts from Neolithic Çatalhöyük (central Anatolia). With each technique the artifacts formed two compositional groups that correlated with the East Göllü Da? and Nenezi Da? sources. The non-destructive capabilities of these methods are emphasized (albeit with certain analytical limitations in the case of SEM-EDS), suggesting important new techniques for Near Eastern obsidian provenance studies.     

Increasing data (INAA) on Ecuadorian obsidian artifacts: preliminary provenance and a clue for pre-Columbian eastward trade

In this work we carried out INAA major (Na, K, Ca and Fe %) and trace (ppm) elements (plus Mn by FAAS analysis) of 15 obsidian samples (waste flakes) coming from an unknown archaeological site (¹⁴C-AMS age of 1425 AD) located on the south-eastern flank of the back-arc Sumaco volcano (to the east of the Cordillera Real) and from two already known pre-Columbian archaeological localities: La Florida (Quito) and Milan (Cayambe). Literature compositional data of the Ecuadorian obsidian outcrops provide some constraints on the provenance of the analyzed waste flakes, even though different methods of analyses make comparisons a difficult task. Concerning the obsidian artifacts of La Florida and Milan, they come from the well known Sierra de Guamanì obsidian sources (Cordillera Real). By contrast, the obsidian fragments of the Sumaco settlement show some compositional characters compatible with obsidian erratic pebbles recently discovered in some river banks of the Amazonian foothills draining the easternmost flanks of the Antisana volcano in the Cordillera Real as well. In this way, the obsidian artifacts found at the Sumaco site reinforce the opinion that Ecuadorian source inventory is not yet exhaustive. Although the Antisana volcano seems to be the best candidate to find out additional primary outcrops of obsidian sources, it cannot be also excluded that sub-Andean and Amazonian people directly took advantage from obsidian secondary sources (e.g. river banks), rather than procurements from primary outcrops in the Cordillera Real. The new archaeological findings at the Sumaco volcano are really of paramount importance in tracing the ancient routes of a possible obsidian eastward trade toward the Amazonian region.     

Obsidian source characterization in the Cordillera Real and eastern piedmont of the north Ecuadorian Andes

Recent research in the Quijos and Cosanga valleys of the eastern piedmont of Ecuador’s Cordillera Real has revealed and substantiated previous knowledge of obsidian sources that are unrelated to obsidian flow systems in the Sierra de Guamaní, Ecuador. Neutron Activation Analysis (NAA) and X-ray Fluorescence (XRF) were carried out on 47 obsidian source samples collected from several contexts in and adjacent to the study area. From samples within the study area three distinct obsidians were characterized: Cosanga A, Cosanga B, and Bermejo. These obsidians originate from a number of obsidian-bearing rhyolitic domes recently identified in the hills west of the Río Cosanga. Extensive survey of these dome localities has identified obsidian cobbles large enough for formal and informal tool manufacture. Beyond the study area, samples were collected and analyzed from the El Tablón source in the Sierra de Guamaní, providing much needed data on this poorly understood source. In addition, a sample from the newly identified Conda Dome source, near the Cotopaxi volcano, was characterized with XRF. All samples were then compared to 57 pre-existing samples from the Mullumica–Callejones, Yanaurco–Quiscatola and Carboncillo sources in the Ecuadoran Cordillera Real, as well as to artifacts from the Sumaco area in the Ecuadorian Amazon. Results of the elemental characterization indicate that the Cosanga Valley, El Tablón and Conda Dome obsidians are chemically distinct. Further, visual characteristics of Cosanga Valley obsidian types are useful in source attribution for the large artifact samples from the region. Finally, obsidian collected from the El Tablón flow suggests that this source may have produced obsidian suitable for tool manufacture.     

THE PROVENANCE OF OBSIDIAN ARTEFACTS FROM THE WĀDĪ ATH‐THAYYILAH 3 NEOLITHIC SITE (EASTERN YEMEN PLATEAU) BY LA–ICP–MS

The geological sources of obsidian in the Red Sea region provide the raw material used for the production of obsidian artefacts found in prehistoric sites on both sides of the Red Sea, as far afield as Egypt, the Persian Gulf and Mesopotamia. This paper presents the chemical characterization of five obsidian geological samples and 20 prehistoric artefacts from a systematically excavated Neolithic settlement in highland Yemen. The major element concentrations were determined by SEM–EDS analysis and the trace element concentrations were analysed by the LA–ICP–MS method, an almost non‐destructive technique capable of chemically characterizing the volcanic glass. A comparison of archaeological and geological determinations allows the provenance of the obsidian used for the Neolithic artefacts to be traced to definite sources in the volcanic district of the central Yemen Plateau.     

MULTIPLE PRIMARY AND SECONDARY SOURCES FOR CHEMICALLY SIMILAR OBSIDIANS FROM THE AREA OF PORTADA COVUNCO,WEST‐CENTRAL NEUQUÉN,ARGENTINA

In west‐central Neuquén Province, Argentina, in the area around Estancia Llamuco, west of Zapala, south of Las Lajas and north‐east of Lago Aluminé, there are multiple primary and secondary sources of obsidian. Primary sources occur within the south‐east extension of the Plio‐Quaternary volcanic chain that runs from Copahue volcano through Pino Hachado. Secondary sources include river‐bed gravels within the valleys of Arroyo Cochicó Grande and Río Kilca as far south as where this river joins with Río Aluminé, and the Quaternary fluvial–glacial sediments cut by the valley of Río Covunco as far east as Portada Covunco. Visually variable obsidians from these two secondary sources include homogeneous black and grey‐translucent types, porphyritic and banded types, and an abundant quantity of oxidized red and black obsidian. However, all these visually distinct obsidians have similar and unique chemistry, with Ba between 220 and 340 ppm, different from any other obsidians previously reported from Neuquén, which all have Ba > 500 ppm, as do obsidians from sources to the north in Mendoza and to the west in Chile. This chemical distinctive obsidian has been exploited and transported over a wide area, beginning prior to 4000 bp , and occurs in local archaeological sites, as well as sites ≥ 300 km to the north‐east in La Pampa Province, ～430 km to the south in Chubut Province, and >75 km to the west across the Andean drainage divide in Chile.     

Obsidian provenance analyses at Göytepe,Azerbaijan: Implications for understanding Neolithic socioeconomies in the southern Caucasus

This study presents a provenance analysis of the Neolithic obsidian assemblages from the early to mid‐sixth millennium bc settlement at Göytepe, Azerbaijan. The study is unique in that (1) it involves a complete, non‐selected obsidian assemblage (901 artefacts) from one particular area of the site; (2) the material is derived from a well‐stratified sequence of 10 securely radiocarbon‐dated architectural levels; and (3) the use of an extraordinarily wide range of sources (more than 20) was identified by provenance analysis using energy‐dispersive X‐ray fluorescence. The results reveal a previously unknown diachronic change in obsidian use in the region, suggesting the occurrence of significant socioeconomic changes during the Late Neolithic of the southern Caucasus.     

New Insights into the Provenance of the Obsidian Fragments of the Island of Ustica (Palermo,Sicily)

In this study we applied a multidisciplinary approach, coupling geophysical and geochemical measurements, to unveil the provenance of 170 obsidian flakes, collected on the volcanic island of Ustica (Sicily). On this island there are some prehistoric settlements dated from the Neolithic to the Middle Bronze Age. Despite not having geological outcrops of obsidian rocks, the countryside of Ustica is rich in fragments of this volcanic glass, imported from other source areas. The study of obsidian findings was carried out first through visual observations and density measurements. At least two different obsidian families have been distinguished, probably imported from Lipari and Pantelleria islands. Analysing the magnetic properties of the samples, these two main sources were confirmed, but the possibility of other provenances was inferred. Finally, we characterized the geochemical signature of the Ustica obsidians by performing microchemical analyses through electron microprobe (EMPA) and laser ablation (LA–ICP–MS). The results were compared with literature data, confirming the presence of the Lipari and Pantelleria sources (Sicily) and indicating for the first time in this part of Italy a third provenance from Palmarola island (Latium). Our results shed new light on the commercial exchanges in the peri‐Tyrrhenian area during the prehistoric age.     

The Origin of 18th–19th Century Tin‐Glazed Pottery from Lorraine,France

Forty‐eight tin‐glazed ceramic fragments (faiences) from Lorraine, found in excavations or pertaining to objects in collections, were subjected to X‐ray fluorescence analysis to determine the bulk, major, minor and trace element compositions. Sixteen superficially clay layers from the surroundings of Lunéville and Saint‐Clément were also analysed. The faiences are, with four exceptions, MgO rich. The combination of stylistic and chemical arguments allowed the recognition of 28 objects that were attributable to the important faience manufactory of Jacques II Chambrette in Lunéville. This reference group was used to test the provenance of high‐Mg faiences from private collections. The latter are not from the manufactory of Le Bois d'Épense/Les Islettes as commonly assumed, but most probably belong to Lunéville and Saint‐Clément. According to archival sources, the potters mixed three clays for the pastes. Some prospected clays are MgO rich due to the presence of dolomite and other Mg‐bearing minerals, but not as high as the faiences, a fact that can be explained by the sampling of de‐carbonatized layers.     

Sources of obsidian artefacts,exchange networks and landscape use in Auca Mahuida (Neuquén,north-western Patagonia)

The results of the X-ray fluorescence (XRF) analysis of 59 obsidian samples from 11 archaeological sites in the Auca Mahuida region of north-western Neuquén, Argentina, are present. They indicate that several obsidian sources were used; however, the intensities of their exploitation were variable. Strong differences appear between the Colorado River basin, characterized by a low variability of obsidian groups from northern Neuquén; the Auca volcano, with a low variability of obsidian groups, but from local sources located north and southwards of the study area; and along Bajo del Añelo, which presents a high variability of obsidian groups from several local and non-local sources. The pattern recorded fits different mechanisms of access to the sources and the conveyance of obsidian across the landscape. Two distinct paths of direct access are suggested for obsidian availability along the Colorado River in northern Neuquén and for Portada Covunco obsidian in central Neuquén. Additionally, the presence of obsidian from sources in southern Neuquén province (Cerro Las Planicies-Lago Lolog), located about 350 km from the study area, is suggested. While not yet conclusive, this possibility parsimoniously integrates the available geochemical and spatial information, allowing the existence of either long-distance transport or indirect access by exchange or similar mechanisms to be proposed.     

NON‐DESTRUCTIVE ANALYTIC METHOD USING XRF FOR DETERMINATION OF PROVENANCE OF ARCHAEOLOGICAL OBSIDIANS FROM THE MEDITERRANEAN AREA: A COMPARISON WITH TRADITIONAL XRF METHODS*

A non‐destructive analytical method using wavelength‐dispersive X‐ray fluorescence (WDXRF) that allows the establishment of the provenance of archaeological obsidians was developed and a comparison with the classical XRF method on powders is discussed. Representative obsidian samples of all the geological outcrops of archaeological interest of the Mediterranean area (Lipari, Pantelleria, Sardinia, Palmarola and the Greek islands of Melos and Gyali), were analysed with the normal procedures used in rock analysis by XRF (crushing, powdering and pelletizing). The non‐destructive XRF analysis was instead conducted on splinters taken from the original geological pieces, with the shape deliberately worked to be similar to the refuse usually found at archaeological sites. Since the analysis was conducted on the raw geological fragment, intensity ratios of the suitably selected chemical elements were used, instead of their absolute concentrations, to avoid surface effects due to the irregular shape. The comparison between concentration ratios (obtained by traditional XRF methods) and the intensity ratios of the selected trace elements (obtained from the non‐destructive methodology) show that the different domains of the chemical composition, corresponding to the geological obsidians of the source areas, are perfectly equivalent. In the same way, together with the geological splinters, complete archaeological obsidians, from Neolithic sites, may be analysed and their provenance may be determined. The proposed non‐destructive method uses the XRF method. Due to its sensitivity, low cost and high speed, it is surely an extremely valid instrument for the attribution of the provenance of the archaeological obsidian from Neolithic sites.     

SEM-EDS characterization of western Mediterranean obsidians and the Neolithic site of A Fuata (Corsica)

During the Neolithic, obsidians of the Monte Arci (Sardinia) volcanic complex were by far more used in the northern Tyrrhenian area than those of the three other source-islands (Lipari, Palmarola, Pantelleria) in the western Mediterranean. It is shown that merely determinations of content for six major elements with a scanning electron microscope by energy dispersion spectrometry (SEM-EDS) are sufficient to distinguish the four types of Monte Arci obsidians. Because of the compositional similarities between these obsidian types, a multivariate analysis is recommended in provenance studies. Although SEM-EDS, electron microprobe-wavelength dispersion spectrometry (EMP-WDS) and particle induced X-ray emission (PIXE) give essentially concordant results in the determination of these six element contents, subtle technique-related biases prevent the combination of SEM-EDS, EMP-WDS and PIXE data on source samples for provenance purposes. An SEM-EDS test-study reveals the first occurrence of obsidians of Lipari for the A Fuata Middle to Late Neolithic site of NW Corsica (north of Sardinia), in addition to the usual Monte Arci obsidians. Similar to EMP-WDS, the SEM-EDS technique requires only millimeter-sized fragments.     

A Petrographic Study of the Anthropomorphic Stelae from the Megalithic Area of Saint‐Martin‐De‐Corléans (Aosta,Northern Italy)

The Megalithic Area of Saint‐Martin‐de‐Corléans (Aosta, northern Italy) consists of anthropomorphic stelae dated to the Copper Age and the beginning of the Early Bronze Age. They were carved in different lithologies of varying provenance according to two successive artistic styles, ‘ancient’ and ‘evolved’. A minero‐chemical and a petrographic investigation were carried out on 47 stelae and on reference samples collected from eight different outcrops, aiming to define the provenance of the stone materials. The variety of rocks used for the manufacture of the stelae reflects the geological complexity of the Aosta Valley. Most of the stelae examined were classified as foliated impure marbles, grey banded marbles (‘Bardiglio’), calcschists and metabasites belonging to the Combin Zone (Piedmont Nappe), which outcrops in close proximity to the Megalithic Area. Some stelae of the evolved group consisted of massive marbles with silicate‐bearing layers, attributed to the Sion–Courmayeur Zone. Similar stone materials were reported for the stelae of the same age found at the archaeological area of Petit Chasseur (Sion, Switzerland). This is archaeometric confirmation of the archaeological affinity between the stelae occurring at the two prehistoric sites, supporting the hypothesis of cultural exchanges over the Grand St Bernard Pass since the Early Copper Age.     

Non-destructive PXRF analysis of museum-curated obsidian from the Near East

Non-destructive pXRF has the potential to expand sample populations of archaeological provenancing studies by facilitating access to museum collections of artefacts. In this study, we use museum-curated obsidian for the sites of Tell Brak, Mersin-Yümüktepe and Tell Arpachiyah and geological obsidian samples from central Turkey to demonstrate that non-destructive pXRF is comparable to other techniques in differentiating between Near Eastern obsidian sources. Secondly, we use multivariate analysis to evaluate whether non-destructive pXRF is sufficiently accurate and precise to enable comparison with legacy datasets from previous analysis using PIXE and ICP-MS. Multivariate analyses show that instrumental offsets between the results from pXRF and other analytic techniques are less than source-to-source variation typical for most Anatolian obsidian outcrops and pXRF-identified geochemical groups are directly comparable to legacy datasets. Non-destructive pXRF analysis indicates that during the Chalcolithic, East Göllü da? and Nenezi da? continued to be the major sources of obsidian to communities in central Anatolia and the Bingöl range and mountains surrounding Lake Van supplied sites east of the Levant. Variations in the analysed assemblages suggest a number of obsidian exchange networks existed during this period.     

Characterization of archaeological obsidians from Lagartero, Chiapas Mexico by PIXE

Obsidian samples from the archaeological site of Lagartero, Chiapas, Mexico and other samples from Mexican and Guatemalan sources were analyzed by proton induced X-ray emission. Statistical treatments such as principal-component analyses were applied to the data set. Obsidians from Lagartero were identified as coming from two obsidian sources in Guatemala and one in Mexico, thus indicating that there was contact between people of Lagartero and other Mayans or Mesoamericans.     

Special Studies: The Obsidian Trade at Isla Cerritos,Yucatán,Mexico

Abstract

Provenience analysis of a small sample of obsidian artifacts from Isla Cerritos, a Terminal Classic/Early Postclassic Itzá trading port on the north coast of Yucatán, indicates a wide range of raw material sources from Central Mexico to the Guatemalan Highlands. The overwhelming predominance of Central Mexican obsidian reinforces the notion that Isla Cerritos was the main trading port of Chichén Itzá. The analysis also provides an indirect approximation of the Itzá obsidian trade networks, which were heavily reliant on sources that may have been under the control of the Toltec capital at Tula.     

SOURCING OBSIDIAN FROM NEOLITHIC ÇATALHÖYÜK (TURKEY) USING ENERGY DISPERSIVE X‐RAY FLUORESCENCE*

This paper details the chemical sourcing of 42 obsidian artefacts from a single Neolithic structure at Çatalhöyük (central Anatolia), using Energy Dispersive X‐Ray Fluorescence (EDXRF). The chemical signatures of the samples match those of two geological sources in southern Cappadocia: East Göllü Da? and Nenezi Da?. The data provide a counterpoint for previous analyses at the site, and suggest possible intra‐community distinctions with regard to shifts in raw material procurement and technical change.