The magnetic sourcing of obsidian samples from Mediterranean and near Eastern sources

The magnetic properties of obsidians are examined for their potential in sourcing obsidian artifacts. The three simplest to determine magnetic parameters—initial intensity of magnetization, saturation magnetization and low field susceptibility—are found to be effective discriminants of many Mediterranean, Central European and near Eastern sources. Although the between-source precision is not as good as geochemical analyses of minor and rare-earth elements, the technique demonstrated the existence of new sources that were subsequently confirmed by minor element analyses. Unfortunately some key sources do not appear to be readily distinguishable on these three simple magnetic parameters alone, although more sophisticated magnetic analyses may prove diagnostic. Despite this, it would appear that effective discrimination can be made in many cases, occasionally with more precision than minor element analyses. This technique therefore offers, as a minimum, a preliminary sourcing tool for use in many areas of the world, thus reducing the number of expensive geochemical analyses. Furthermore, its very low cost, non-destructive nature and speed open the possibility of quantitative evaluation of trade routes based on obsidian distributions, particularly as versions of the equipment are now suitable for use in the field.     

Obsidian sources and distribution systems in Island Southeast Asia: a review of previous research

This paper summarises research on obsidian findings across the region of Island Southeast Asia (ISEA), from the first reporting of obsidian on Sumatra as a result of cave excavations in the early 1900s through to the latest published discoveries in 2009. These results are the background for the first region-wide research project focussing on obsidian characterisation and its role in prehistoric inter-island exchange. It is commonly held that distribution of obsidian in ISEA was only localised and inter-island transportation limited. The review, however, suggests that this hypothesis derives from an incomplete knowledge of obsidian distribution in the region rather than typifying prehistoric social patterns. Obsidian sourcing has been carried out only intermittently in ISEA since the 1970s and has generally been focussed only at the single site level, thus explaining this very partial understanding.     

Obsidian sources and distribution systems in Island Southeast Asia: new results and implications from geochemical research using LA-ICPMS

This paper discusses new evidence of long-distance interaction networks in Island Southeast Asia obtained from geochemical analyses using SEM-EDXA and LA-ICPMS of 101 obsidian samples from 25 locations including seven obsidian sources and 19 archaeological sites. Given that there are obsidian sources distributed throughout much of Island Southeast Asia, the potential for obsidian studies to provide greater understanding of patterns of mobility and exchange in the Pre-Neolithic and Neolithic periods would seem to be considerable. This potential, however, remains largely unrealised as obsidian sourcing has hitherto only been carried out intermittently in Island Southeast Asia using PIXE-PIGME, XRF and other methods.     

Comparison of XRF and PXRF for analysis of archaeological obsidian from southern Perú

Chemical sourcing is becoming an increasingly important component of archaeological investigation. Instruments used for elemental analysis generally must be operated in a controlled laboratory environment. Further, many methods require destruction of a small portion of the objects under investigation. These facts inhibit the application of chemical sourcing studies in a number of research contexts. Use of portable non-destructive instruments would resolve these issues. Sixty-eight obsidian artifacts from the site of Jiskairumoko, in southern Perú, were examined by X-ray fluorescence spectrometry (XRF) and portable X-ray fluorescence spectrometry (PXRF). Results were compared for consistency in terms of source determination and individual element concentrations. Both instruments determined that the same sixty-six artifacts derived from the Chivay obsidian source and both identified the same two artifacts that could not be assigned to source. Individual element comparisons showed significant differences, but these can be resolved through instrument cross calibration, and differences had no bearing on source identification. PXRF was found suitable for determining obsidian sources in southern Perú and for identifying specimens that require more sensitive analytical methods such as, instrumental neutron activation analysis (INAA). Regular use of Chivay at Jiskairumoko suggests consistent trade relationships developed during the Archaic.     

A provenance study of archaeological obsidian from the Andahuaylas region of southern Peru

To date, most obsidian sourcing studies in the Andes have concentrated on the highlands and Titicaca Basin of far southern Peru and northern Bolivia. Toward achieving a more complete understanding of the region, this paper offers new data on the long-term prehistoric obsidian procurement and consumption patterns in the Andahuaylas region of the south-central Peruvian highlands. Obsidian sourcing data from Andahuaylas are particularly interesting since the area is centrally located among several important regional obsidian sources. A total of 94 obsidian samples from a range of sites of different temporal periods were chemically analyzed using portable X-ray fluorescence (PXRF), as well as laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The results demonstrate a number of interesting trends, the first of which is the long-term importance of the Potreropampa obsidian source to populations of the Andahuaylas region from at least the early Formative period (∼2500 BCE). Secondly, the results indicate that procurement strategies by local populations in Andahuaylas were primarily reliant on nearby (<150 km) obsidian sources. Finally, the paucity of more distant, yet widely exchanged, high quality obsidian (i.e., Chivay, Alca) confirm that as a region, Andahuaylas was more heavily connected economically (and likely culturally) with local areas to the south (Apurímac) and to the west (Ayacucho).     

Assessing the applicability of portable X-ray fluorescence spectrometry for obsidian provenance research in the Maya lowlands

Recent innovations in portable energy-dispersive X-ray fluorescence (PXRF) spectrometry have increased its utility for the geochemical characterization of obsidian artifacts for archaeological provenance research. However, concerns over the utility of PXRF instrumental analyses have been raised, focused on the validity and reliability of the geochemical data produced. Here we adopt the framework of Richard Hughes (On Reliability, Validity, and Scale in Obsidian Sourcing Research, 1998), whereby reliability addresses instrument stability and issues of measurement while validity pertains to an instrument’s ability to discern geochemical source provenance. This is done in order to test the utility of PXRF instruments for archaeological provenance research. k-Means cluster analysis was used to test the accuracy of PXRF through statistical comparison of data acquired via laboratory and portable energy-dispersive XRF instruments. Multivariate analysis was employed to demonstrate obsidian source representation at two Classic Maya archaeological sites in southern Belize – Uxbenká and Ek Xux – and to test the validity of data obtained from a PXRF instrument in answering archaeological research questions pertaining to regional interactions between lowland Maya polities. Results suggest that portable XRF instruments produce internally consistent results. However, data acquired from a PXRF instrument are not statistically equivalent to other XRF instruments. This is to say that while PXRF is not a reliable technique, it is valid for questions pertaining to geochemical source representation.     

Networks and Neolithisation: sourcing obsidian from Körtik Tepe (SE Anatolia)

This paper details the use of obsidian sourcing to reconstruct networks of interaction (or ‘communities of practice’) amongst populations of south-eastern Anatolia and the Near East in the context of ‘Neolithisation’ during the late 11th–early 10th millennia BC. EDXRF was used to elementally characterise 120 artefacts of Epi-Palaeolithic – Pre-Pottery Neolithic A date from Körtik Tepe in south-eastern Anatolia. Four eastern Anatolian sources are represented, mainly Bingöl A/B and Nemrut Da?, plus the first evidence for the use of Mu? obsidian. When the source data is integrated with the artefacts' techno-typological attributes it is possible to locate the assemblage within an Upper Tigris tradition (with some interesting local differences), which stands in stark contrast to contemporary practices in northern Mesopotamia and the Levant. These local and regional distinctions support recent views of the Neolithic being much more heterogeneous, with a ‘mosaic’ of community-specific/local traditions of subsistence practices, raw material choices and lithic technologies during the Younger Dryas–Early Holocene.     

Initial source evaluation of archaeological obsidian from the Kuril Islands of the Russian Far East using portable XRF

Obsidian artifacts recently have been recovered from 18 archaeological sites on eight islands across the Kuril Island archipelago in the North Pacific Ocean, suggesting a wide-ranging distribution of obsidian throughout the island chain over the last 2,500 years. Although there are no geologic sources of obsidian in the Kurils that are known to have been used prehistorically, sources exist in Hokkaido, Japan, and Kamchatka, Russia, the southern and northern geographic regions respectively from which obsidian may have entered the Kuril Islands. This paper reports on the initial sourcing attempt of Kuril Islands obsidian through the analysis of 131 obsidian artifacts. Data from this research were generated through the application of portable XRF technology, and are used to address research questions concerning prehistoric mobility, exchange, and social networking in the Kuril Islands.     

Source provenance of obsidian artifacts from the Early Stone Age (ESA) site of Melka Konture,Ethiopia

The source provenance of 10 Early Stone Age artifacts from the localities in Melka Konture has been determined by EDXRF. Results show that the early to mid-Pleistocene makers of the artifacts derived the raw material from a source located in their proximity, supporting the previously proposed short distance transport of raw material for the time period.     

Patterning in procurement of obsidian in Chaco Canyon and in Chaco-era communities in New Mexico as revealed by X-ray fluorescence

X-ray fluorescence analysis of obsidian artifacts from sites located in Chaco Canyon and from three Chaco-era communities in New Mexico permits determination of their geological origin. These source data are used to describe patterning in obsidian procurement in sites located in Chaco Canyon dating from A.D. 500–1150, and in a three non-Canyon communities occupied during the period of Chaco Canyon's regional prominence (ca. A.D. 875–1150). These data demonstrate that the most proximate sources generally dominate the sourced obsidian assemblages from sites of all periods, but also suggest differences in procurement patterning both over time and across space. Within Chaco Canyon, there is a notable shift from Mount Taylor obsidian to use of Jemez Mountains sources over time. These data also suggest that earlier analyses of obsidian from sites in Chaco Canyon misidentified some obsidian artifact sources; these new data indicate the central areas of disagreement and provide a revision of procurement patterning. In the Chaco-era communities located outside Chaco Canyon, procurement patterning diverges. The Blue J community shows an increase in use of the nearby Mount Taylor source over time. Two communities located toward the southern extent of the Chaco great house distribution reveal a markedly distinct procurement pattern, obtaining nearly all of their obsidian from southern sources largely unrepresented at Chaco Canyon. Combined, these data provide new insights into raw material procurement and artifact production at sites in Chaco Canyon, and in communities occupied during the Chaco Phenomenon, the period of the Canyon's greatest regional influence.     

Ancient social landscapes of northwestern Argentina: preliminary results of an integrated approach to obsidian and ceramic provenance

This article presents the results of ongoing instrumental neutron activation analyses (INAA) conducted on archaeological artifacts from the Formative period of northwestern Argentina (NWA). These studies are part of a wider archaeological project that seeks to understand the structure of the social landscape of the period by examining domestic and burial evidence from a wide range of villages across the area known as the southern Calchaquí valleys. Elemental data is discussed in the light of its potential contribution to reassess past social interaction strategies in the region.     

Strofilas (Andros Island,Greece): new evidence for the cycladic final neolithic period through novel dating methods using luminescence and obsidian hydration

The recently excavated coastal prehistoric settlement of Strofilas on Andros Island (Cyclades, Greece) in the Aegean sheds new light on the transitional phase from the Final Neolithic to Early Cycladic period regarding masonry, fortification, and richly engraved rock art. The fortification possesses early evidence of preserved defensive architecture, as evidenced from the plethora of scattered finds from within and around the settlement. Important features are carvings on rock walls which mainly depict ships, animals, and fish. Initial archaeometric dating via the application of luminescence dating of two samples from the fortified wall bearing engraved ships, and by obsidian hydration of two blades employing the new SIMS-SS method (secondary ion mass spectrometry via surface saturation), has been undertaken to determine the site's chronology. The former yields an average date of 3520 (±540) BC and the latter an average date of 3400 (±200) years BC, both of which, within overlapping errors, suggest the main settlement occurred during the Final Neolithic.     

Provisioning of the Inka army in wartime: obsidian procurement in Pambamarca,Ecuador

Ninety-nine obsidian artifacts from fortified and non-fortified sites in the Pambamarca region of northern Ecuador were analyzed with XRF to examine patterns of procurement of obsidian by soldiers in the Inka army and by the local Cayambes who were resisting Inka conquest. The results show that the Inkas acquired material from several different sources, a pattern consistent with provisioning by subject peoples in partial fulfillment of labor obligations. The Cayambes also acquired material from multiple sources, although they may not have directly procured material from all of the sources because the external boundary of Inka territory bisected the region of obsidian sources. That frontier may have prevented the Inkas from accessing one source, Callejones, from which the Cayambes acquired some of their obsidian. In addition, the Inkas were acquiring some obsidian from the Yanaurco-Quiscatola source, which had been previously abandoned around AD 1000.     

Testing the accuracy of portable X-ray fluorescence to study Aztec and Colonial obsidian supply at Xaltocan,Mexico

This article demonstrates the accuracy of non-destructive portable X-ray fluorescence (pXRF) for the study of obsidian in central Mexico. Obsidian sources were identified for a sample of 103 artifacts from the site of Xaltocan, which spanned the rise and fall of the Aztec empire and the first centuries of Spanish colonial rule (AD 900–1700). Sources were assigned by comparing pXRF measurements with previously published source data and were verified using the standard techniques of laboratory XRF (lXRF) and instrumental neutron activation analysis (INAA). Additional tests of potentially confounding factors show that neither length of read time, presence of surface residue, nor incomplete detector coverage due to small artifact size compromised our ability to attribute sources to artifacts. Concave surfaces did decrease the accuracy of readings because of the greater distance between the artifact and the detector. Our results provide new insight into the stability of supply networks and markets well into the Colonial period as well as the homogenizing tendencies of the Aztec market system.     

A pilot study of “black chert” sourcing and implications for assessing hunter-gatherer mobility strategies in Northern England

Mesolithic hunter-gatherer logistic strategies and raw material procurement locales have been topics of considerable interest in northern England, accelerated by the early discoveries at Star Carr. Here we present the results of a pilot study investigating the potential for geochemically sourcing “black chert”, a material with similar qualities to flint but of inland limestone origin, using ICP-AES, ICP-MS and LA-ICP-MS. Several geological sources of black chert are known, and it is commonly present at upland Mesolithic sites along the Pennine chain. Four geological sources were sampled and analysed, along with a small sample of black chert artefacts from two upland Pennine archaeological sites. The results demonstrate that the four sampled sources can be easily differentiated from one another chemically. This research reveals the potential to apply this approach at a larger scale; the archaeological sample together with the source results indicate that additional sources will need to be identified and sampled before such data can be applied to address current questions of the Mesolithic of northern England.     

Forensic Ar/Ar dating: a provenance study of Middle Stone Age obsidian artifacts from Ethiopia

Obsidian sourcing based on geochemistry is widely applied to reconstruct commerce patterns and dissemination of early hominid groups. Due to problems concerning potential intra-source variability or homogeneity of a geological source over large areas, parameters additional to this classical approach are desirable. Here we present the first ⁴⁰Ar/³⁹Ar investigation of Middle Stone Age (MSA) obsidian artifacts (i.e. debitage pieces) for this purpose, as well as of potential geological obsidian sources from Ethiopia. With the present pilot study we demonstrate that ⁴⁰Ar/³⁹Ar geochronology represents a reliable and powerful tool for archaeological provenance studies complementary to the geochemical approach and more recently applied techniques like fission track counting or Mössbauer spectroscopy. Two independent sets of debitage and potential source rock samples were dated by the ⁴⁰Ar/³⁹Ar method. Debitage pieces from the Kulkuletti excavation site and obsidian samples from the nearby obsidian outcrop Worja (central Ethiopia) exhibit basically identical age ranges as well as similar Ca/K and Cl/K ratios, supporting the debitage/source rock relationship previously inferred on geochemical grounds. A second small set of geochemically characterized debitage samples from the Porc Epic cave and potential source rocks from an obsidian outcrop at Kone (Eastern Ethiopia) however have different ⁴⁰Ar/³⁹Ar ages and Ca/K and Cl/K ratios. These results contradict the previous conclusion about a debitage/source rock relationship of the Porc Epic and Kone samples made on the basis of geochemistry [A. Negash, M.S. Shackley, Archaeometry 48 (2006) 1]. Additional sampling at the Kone outcrop as well as of other obsidian occurrences in the greater area is needed to unambiguously pinpoint the origin of these obsidian tools.     

Preliminary characterization and regional comparison of the Dasht-i-Nawur obsidian source near Ghazni,Afghanistan

Archaeologists have known that an obsidian source exists in the Dasht-i-Nawur basin of central Afghanistan since at least the 1970s; however, regional political turmoil and instability have prevented in-depth study of this source. Data presented here from recent analyses of archival specimens of obsidian collected during a 1976 survey provide a preliminary geochemical profile for this obsidian source. These data suggest that the Dasht-i-Nawur source is easily distinguishable from other obsidian sources in the Near East and southwest Asia. Comparison of these data to an existing database of artifact compositional profiles suggests that initial hypotheses about restricted distribution of the Dasht obsidian may be correct. These data provide for the first time the characterization of a long-known but poorly studied obsidian source. Additionally, this study serves as one example of the benefits gained through working to maintain and preserve data archives of now-closed laboratories.     

The signs of the sacred: Identifying shamans using archaeological evidence

Anthropologists have determined that shamanism is a robust cross-cultural pattern, but they still have many methodological and theoretical issues to resolve. Central to archaeological religious studies is the need to develop a general and rigorous methodology for identifying the presence and structure of shamanism. This discussion begins by discussing shamans as a polythetic class and proposes that shamans and priests as they are commonly defined do not represent dichotomous religious structures, but rather reflect two ends of a continuum. The paper then presents a methodology for identifying and studying shamanism based on cross-cultural regularities in shamanic tools (sacra) and shamanic experiences. The methodology is then applied to the Casas Grandes region and Pottery Mound, both from the North American Southwest, and indicates that shamanic ritual was likely present during the late prehistoric occupation of the region.     

Obsidian sources in highland Yemen and their relevance to archaeological research in the Red Sea region

The Red Sea and surrounding area formed through dynamic uplift and rifting of Afro-Arabia, and associated volcanism (both oceanic and continental in character). As a result, volcanic landforms and products are widespread and play a vital role in the natural and cultural landscapes of humans occupying the highlands and lowlands on both sides of the Red Sea. Archaeologists have suggested for some time that Afro-Arabian trade in obsidian had its roots in the prehistoric period and that the region was very likely the source of an abundance of obsidian artefacts found as far afield as Egypt, the Persian Gulf and Mesopotamia, and which do not match the well-known Anatolian, Transcaucasian or Mediterranean sources. Nonetheless, the southern Red Sea is one of the few obsidian-rich regions exploited in antiquity that has been barely investigated. In this paper, we highlight new geochemical analyses (carried out by LA-ICP-MS) of obsidian sources in Southern Arabia and beyond, that enhance our knowledge of obsidian exploitation from as early as the Neolithic period, and which enable us to evaluate the role that highland Yemen obsidian sources played in prehistoric long-distance trade. In addition, we present new evidence for explosive volcanic eruptions that likely affected the highland populations of Yemen in the 4th millennium BC.     

Development and evaluation of geochemical methods for the sourcing of archaeological maize

Strontium (Sr)-isotope values on bone from deer mice pairs from 12 field sites in the Chaco Canyon area, New Mexico, were compared with isotope values of synthetic soil waters from the same fields. The data indicate that mice obtain Sr from near-surface sources and that soil samples collected at depths ranging from 25 to 95 cm contain Sr that is more accessible to the deep roots of maize; thus, synthetic soil solutions provide better data for the sourcing of archaeological maize. However, the Sr-isotope composition of mice may be more valuable in sourcing archaeological remains of animals such as rabbit, turkey, and deer.