A study of mesoamerican obsidian sources using activation analysis

An extensive study of Mesoamerican obsidian source samples from 37 sites has been begun to better differentiate and define the trace element content at known Mesoamerican obsidian quarries, with particular emphasis on those in Mexico. This paper reports on the first results in that study as well as studies of sample contamination by grinding and results for the new National Bureau of Standards No. 278 Obsidian SRM.     

Neutron Activation Analysis of Obsidians from Quarries of the Central Quaternary Trans-Mexican Volcanic Axis

Obsidian samples from 13 Mexican quarries (Sierra de Pachuca and Zacualtipan, Hidalgo, Zaragoza and Oyameles, Puebla, Altotonga Veracruz and eight sites of the Zinaparo — Varal — Churintzio Hills region) have been analyzed by NAA. The concentration of 19 elements, major and trace, are reported. Excepting Altotonga Veracruz, the chemical composition of other obsidian flows was found homogenous. The region of the Varal obsidian was delimited. An excellent correlation between ytterbium and lutetium contents in obsidians was found.     

X-ray fluorescence analysis of obsidian objects from Catamarca,Argentina

The concentrations of five trace elements (Rb, Zr, Sr, Ti and Mn) and one major (Fe) element have been determined in groups of obsidian samples by wavelength dispersive X-ray fluorescence spectrometry. Two methods were used for different elements on the basis of different excitation conditions and sample preparation procedures. Synthetic standards with compositions similar to those of the igneous stone were prepared into which the analytes were incorporated in solution. The method was used to establish the provenance of a number of prehistoric obsidian artifacts. The results ascertained in these analyses are discussed in this paper.     

The provenance of archaeological obsidian artifacts from Northern Chile determined by source-induced X-ray fluorescence

A study of provenance of obsidian artifacts from "site 25-Las Estacas", Quebrada de Jorquera (Copiapó, Northern Chile) was carried out by means of X-ray fluorescence, using radioactive sources. Obsidian samples from different Chilean geological regions, located in South Central Chile (Laguna del Maule volcanic area, sources of La Coloradas and La Plata), "Radal Siete Tazas" and the North of Chile (Copiapó Volcano) were analyzed. The analysis was performed using ¹⁰⁹Cd and ²⁴¹Am annular excitation sources and X-ray fluorescence. This allowed the determination of Fe, Cu, Rb, Sr, 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 Copiapó Volcano source, which is geographically close to the site.     

Chemical characterisations of Carpathian obsidian sources by instrumental and epithermal neutron activation analysis

Obsidian samples from the Tokaj Mountains (Hungary) and from the neighbouring Zemplin Hills (Slovakia) were analysed by instrumental and epithermal neutron activation analysis for obtaining a “fingerprint” for discrimination of potential natural sources of raw material that would permit tracing the origin of archaeological obsidian artefacts. These techniques fully discriminate the Zemplin Hills sources (Carpathian I, eastern Slovakia) and the Tokaj Mountain sources (Carpathian II, north-eastern Hungary) as well as these Central European sources from those already studied of the Mediterranean basin and adjacent regions.     

Dating of hydrated obsidian surfaces by SIMS-SS

A new approach to dating ancient obsidian artifacts based on the modeling of water diffusion profiles is evaluated using multiple archaeological test cases of known age. Hydrogen profiles from hydrated obsidian surfaces have been collected by secondary ion mass spectrometry (SIMS). The H₂O concentration versus depth profiles are modeled and diffusion ages have been produced. SIMS based dates for fourteen obsidian specimens of well-known age, ranging from 300-7000 years old, have been compared with radiocarbon ages. The convergence between the two dating methods is excellent and validates the new dating approach. This revised version was published online in July 2006 with corrections to the Cover Date.     

Provenance studies of obsidian artifacts: Trace elements analysis and data reduction

Iron and trace elements, such as rare-earth elements, scandium, rubidium, cesium, tantalum, thorium and uranium were determined by instrumental neutron activation analysis in geological samples of obsidian rocks from the Mediterranean Area and in obsidian artifacts found in some prehistorical human settlements in Italy. REE patterns and discriminant analysis allow a firm identification of the source material of artifacts, thus confirming and implementing fission track data of the same artifacts and rocks on the origin of the obsidian rock used to mould the artifacts.     

Identification of provenance of obsidian samples analyzing elemental composition by INAA

The results of a study on 111 obsidian artifacts collected during an archaeological campaign performed by the University of Siena near Sesto Fiorentino (Florence, Italy) are reported. Earlier, we used the concentration ratios among some elements as reported in the literature to discriminate the deposit sources. Later, optimizing the characterization and for having a more strong classification, multivariate chemiometric investigation has been performed (multivariate statistical analysis in Principal Components and Discriminating Factor Analysis). The data obtained show three wellseparated groups connected to the relative sites in Lipari and in Sardinia (flows A and C from Arci Mountain).     

Phenocrysts in obsidian glasses

The aim of the current paper is to map minerals mainly of Carpathian obsidian glasses by nuclear microprobe based on the particle induced X-ray emission (PIXE) providing analytical data on them for the first time. Some samples from Armenia, Greece are also involved to make a comparison with the Carpathian specimens. The following minerals are identified and analyzed: pyrrhotite, chalcopyrite, pyrite, zircon, pyroxene, biotite, plagioclase feldspar, and anhydrite. On the basis of rock-forming silicate minerals, some petrologic processes are outlined. With the identification of accessory minerals (anhydrite, pyrrhotite, chalcopyrite, pyrite), some geological conclusions are also drawn.     

Provenance study of obsidian samples by using portable and conventional X ray fluorescence spectrometers. Performance comparison of both instrumentations

The potentiality of portable instrumentation lies on the possibility of the in situ determinations. Sampling, packaging and transport of samples from the site to the laboratory are avoided and the analysis becomes non destructive at all. However, detection limits for light elements are, in most cases, a limitation for quantification purposes. In this work a comparison between the results obtained with an X ray fluorescence spectrometer laboratory based and a portable instrument is performed. A set of 76 obsidian archaeological specimens from northwest Patagonia, Argentina was used to carry out the study. Samples were collected in the area of the middle and high basin of the Limay River. The analytical information obtained with both instrumentations was complemented with Principal Component Analysis in order to define groups and identify provenance sources. The information from both instruments allows arriving to the same conclusion about sample provenance and mobility of hunter-gatherer groups. Three groups of sources were identified in both cases matching with the geographical information. Also, same sets of outlier samples or not associated to these sources were found. Artifact samples were associated mainly to the closest sources, but some of them are related to sources located more than three hundred kilometers, evidencing the large mobility of the hunter-gatherers by the obsidian interchange. No significant differences between concentrations values obtained by laboratory based instrument and portable one were found.     

Sourcing archaeological obsidian by an abbreviated NAA procedure

An abbreviated NAA procedure has been developed to fingerprint obsidian artifacts in the Mesoamerican region. Despite the large number of available sources, an NAA procedure, which relies on producing short-lived isotopes, has been applied with a success rate greater than 90 percent. The abbreviated NAA procedure is rapid and cost competitive with the XRF technique more often applied in obsidian sourcing. Results from the analysis of over 1,200 obsidian artifacts from throughout Mesoamerica are presented.     

Laser microsampling and multivariate methods in provenance studies of obsidian artefacts

The provenance of obsidian artefacts and raw materials was studied by the multivariate statistical analysis of forty-five samples using elemental composition data obtained by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). One ICP-MS instrument equipped with a quadrupole mass filter and the other based on a time-of-flight analyser were coupled to the same type of laser ablation device (Nd:YAG 213 nm), thereby affording a comparison of the different mass spectrometers in terms of precision and verification of the consistency of the results. The influence of surface roughness (polished raw material vs artefact) and microinhomogeneity on the LA-ICP-MS signal was studied under the optimised working conditions of the laser ablation device. Principal component analysis, correspondence analysis, independent component analysis, multi-dimensional scaling, Sammon mapping and fuzzy cluster analysis were applied and compared in order to reveal statistically significant compositional differences between particular geological sites and to disclose the provenance of the raw materials used in manufacture of the artefacts. Twenty-seven artefacts and eighteen raw material samples from natural resources in the Czech Republic, Slovakia, Italy, Greece, Syria, Iraq, Turkey, Mexico and Nicaragua were examined with special attention focused on samples from Moravia (Czech Republic) and some Near East sites (Tell Arbid, Tell Asmar). The Carpathian origin of the obsidian artefacts was investigated in the Moravian samples using the Pb, Rb and U contents. The Near East samples were classified according to their Sr, Ba, Zr and REE contents as per-alkaline obsidians (Bingöl A/Nemrut Da?) originating from Southeast Anatolia.     

Evaluation of trace-element pollution in Barada River environment by instrumental neutron activation analysis

The impact of tanning and electroplating industry on the eastern part of Barada River environment has been evaluated. Sediment, soil and plant samples were collected from nine sites at the river near the eastern industrial complex during 1999. Results of instrumental neutron activation analysis have shown high levels of Cr in sediment collected near the tanning factories; the highest value obtained being 2692 ppm. In addition, relatively high levels of Cr were also found in the agriculture soil collected near the riverbank in the industrial complex; Cr concentrations varied between 77 ppm and 327 ppm. However, Cr concentrations in plant leaves grown at riverbank were found low and this due to strong bounding of Cr to soil. Other trace metals such as copper and nickel were also high in sediment samples. The highest concentration of copper was about 4000 ppm, which is much higher than the natural levels; electroplating shops are the main source of this element in the area. Furthermore, concentrations of the studied trace metals have decreased as the sampling site distance became far from the industrial complex. In general, other trace elements were found to be at low concentrations, but the obtained data can be used as a baseline for future monitoring.     

Determination of the provenance of obsidian samples collected in the archaeological site of San Miguel Ixtapan, Mexico State, Mexico by means of neutron activation analysis

Obsidian samples from San Miguel Ixtapan Mexico State, Mexico were analyzed by means of neutron activation. Statistical treatments such as bivariate, cluster and principal-components analyses were applied to the data set. Obsidians were identified as coming from three important sources: Sierra of Pachuca in the state of Hidalgo, Zinapécuaro and Zináparo-Varal in the state of Michoacán. This revised version was published online in July 2006 with corrections to the Cover Date.     

Provenance and use wears of Pre-Hispanic obsidian scrapers from Metztitlan, Hidalgo, Mexico

The research was performed with archaeological obsidian scrapers, collected at the Metztitlan area, Hidalgo, Mexico. The provenance of the raw material was determined by NAA. SEM technique was applied to identify use wears on pre-Hispanic tools and experimental replicas. The Metztitlan scrapers made of the obsidian of Zacualtipan, Hidalgo, Mexico, were probably used for Agave juice extraction in the Late Postclassical period.     

Determination of trace elements in cloud water and aerosols using instrumental neutron activation analysis and hydride generation with atomic absorption spectrometry

Cloud water and aerosol samples were collected at Whiteface Mountain, NY using the ASRC omnidirectional cloud water collector and high volume samples respectively. Trace element concentrations in cloud water samples were determined by neutron activation analysis and hydride generation with atomic absorption spectrometry. Agreement between the two methods for Se concentration was excellent (0.98±0.05). Aerosol samples were also analyzed for trace elements by neutron activation. Elemental analysis of cloud water and aerosols provide information useful to the study of microphysical and chemical interactions in cloud systems.     

Chemical characterisations of Anatolian obsidians by instrumental and epithermal neutron activation analysis

Obsidian is a volcanic glass which is generally black, sometimes grey, brown, red or green in colour and characterised by a glassy appearance and conchoidal fractures. It is formed by the sudden cooling of the molten, generally acid magma with high water content. Obsidian was widely used for tool-making during prehistoric times. This work concems the chemical characterisation of obsidian occurrences from Northem, Central and Eastem Anatolia by Instrumental and Epithemal Neutron Activation Analysis for obtaining an accurate fingerprint for discrimination of potential natural sources of raw material that would permit tracing the origin of archaeological obsidian artefacts.     

A new method for the analysis of titanium,barium, and arsenic in obsidian via epithermal neutron activation analysis

A new instrumental epithermal neutron activation analysis procedure to quantitatively determine titanium, barium, and bromine in obsidian with improved sensitivity has been developed. The advantage of epithermal activation for Ti, Ba, and Br is demonstrated with multiple geological standards and the ability to determine arsenic in obsidian is demonstrated. The results for titanium are compared to previous electron-microprobe results for Kenyan obsidian.     

Determination of trace elements in total particulate matter of cigarette smoke by instrumental neutron activation analysis

Trace elements play an important role in the metabolism of the human body. Some of the trace elements are essential, whereas others are toxic and even carcinogenic. Cigarette smoke contains many of these hazardous trace elements. Tobacco samples have been analyzed by the authors for their trace element contents and the results have been reported earlier. This paper presents results on the trace element content analyzed in cigarette smoke using an automatic smoking machine developed in this laboratory to simulate actual smoking pattern. The trace element levels in the total particulate matter samples of the cigarette smoke collected on filter papers were measured and compared with those of cigarette smoke condensate reported in the literature. Both methods of collection give comparable results.     

Groundwater Quality at the Huaibei Coalfield,China

The environmental and health impacts of trace elements are of great concern because of their toxicity, persistence, and bioavailability. Twenty-six groundwater samples were collected from the coal mining areas to evaluate water quality and potential environmental impact caused by mining activities. The physical/chemical properties and trace element concentrations (As, Cd, Cr, Cu, Pb, and Zn) were determined. The physical/chemical parameters and the concentrations of trace elements varied among the shallow and confined groundwater, which may indicate the absence of hydraulic interactions between the aquifers. The concentrations of trace elements in the mining areas are higher than at background monitoring sites, which suggests that the mining activities may lead to environmental and health impacts. Based on a health risk assessment, the low hazard quotients and cancer risk values in confined groundwater samples indicate that the chronic and cancer adverse effects due to trace elements are negligible. This study provides a comprehensive assessment of groundwater trace element impacts from coal mining in China and is useful for environmental management.