INVESTIGATING SEASONALITY AND SEASON OF BIRTH IN PAST HERDS: A REFERENCE SET OF SHEEP ENAMEL STABLE OXYGEN ISOTOPE RATIOS

Intra‐tooth sequential analysis of enamel δ¹⁸O is currently used to investigate birth seasonality in past animal populations, offering new insights into seasonal availability of animal resources, herd management and seasonality of site occupation. Reference data sets are still required to address two major difficulties: (1) that inter‐individual variability in the record of the seasonal cycle is affected by tooth size; and (2) that the season of birth cannot be directly estimated from the timing of tooth growth, because of a delay in enamel mineralization. We present a data set acquired on the lower second molar of 10 modern sheep from Rousay (Orkney) born within a few weeks of each other in April/May and submitted to the same environmental conditions until death. All sheep have recorded a sinusoidal pattern of δ¹⁸O variation spanning approximately a year. From the difference between the expected and the measured time sequence, the delay of enamel mineralization is estimated to be 5–6 months. The data set is then described using a model mainly based on a cosine function. The period, corresponding to the length of the M2 crown formed over a year, averaged 35.8 mm. A very slight variation of tooth growth rate with time and no attenuation of the isotopic signal towards the cervical margin of the crown could be detected in this data set. The lowest δ¹⁸O values, corresponding to the sheep's first winter, were tracked at a distance from the enamel/root junction that varied between 23.0 and 30.3 mm (x_min mean = 27.6 mm); the highest δ¹⁸O values, corresponding to the sheep's second summer, were between 6.3 and 11.6 mm (x_max mean = 9.9 mm). Most of the variability can be attributed to tooth size. When normalized on the period, x_min and x_max are 0.28 (± 0.05) and 0.78 (± 0.05) on average, meaning that the Rousay sheep have recorded the minimum and maximum δ¹⁸O values on average at 78% and 28%, respectively, of the end of the periodic cycle recorded in the second molar.     

PETROGRAPHIC AND STABLE ISOTOPE ANALYSES OF LATE CLASSIC ULÚA MARBLE VASES AND POTENTIAL SOURCES*

Ulúa marble vases from the Ulúa Valley of northwestern Honduras are a hallmark luxury good from Late Classic (ad 600–900) Mesoamerica. Archaeological and stylistic data point to centralized production at one site, Travesía. This paper analyses stable isotope and petrographic data from the vases and three potential procurement areas. The results indicate that the vases were produced from one primary source with one, potentially two, secondary sources. Procurement patterns most probably corresponded to contemporary communication routes. The results clearly indicate that a multi‐method approach is necessary for sourcing marble from Honduras.     

LEAD ISOTOPE RATIOS AS A MEANS OF SOURCING ANTHROPOGENIC LEAD IN ARCHAEOLOGICAL SOILS: A PILOT STUDY OF AN ABANDONED SHETLAND CROFT*

Results from soil chemical analysis have demonstrated enhanced concentrations of lead (Pb) associated with archaeological sites. However, interpretation of these Pb concentrations is difficult because of the multitude of possible Pb sources. This pilot study of an abandoned croft in Shetland suggests that Pb isotope ratios have the potential to identify sources of anthropogenic Pb. The results highlight two different Pb associations. The first includes hearth, house floor and house overburden soils, with end members of fuel materials and an unidentified material with a low (< 1.126) ²⁰⁶ Pb/ ²⁰⁷ Pb ratio. The second includes byre, kailyard (garden) and arable soils, with end members of hearth materials and local wind‐blown sand.     

STABLE ISOTOPE ANALYSIS AND DIET IN EASTERN OKLAHOMA

Abstract

Over the last three decades, significant quantitative information on prehistoric diets has come to light from a variety of locations in the Caddoan archaeological area, a region encompassing eastern Oklahoma, western Arkansas, northeast Texas, and northwest Louisiana. Most of this research is based on macro-botanical and faunal remains analysis. As an additional line of evidence for the growing body of botanical and faunal data, stable carbon and nitrogen isotopes in bone collagen were analyzed from 82 human and faunal samples from the Arkansas basin and Ozark Highlands in eastern Oklahoma. The research investigates the role of maize in diets through time and across sex and status dimensions. Spanning six phases, within the time range 300 B.C. to A.D. 1650, mean δ¹³C values increase from –19.2 to –12.7 parts per million ‰. Although present prior to A.D. 1000 substantial increases in the use of maize do not begin until the Harlan phase (A.D. 1050–1250). Even with increased use, maize never dominates the diet to the extent seen in Mississippian period sites farther east.     

CARBON AND OXYGEN ISOTOPE RATIOS OF MARBLES FROM SOME ANCIENT QUARRIES OF WESTERN ANATOLIA AND THEIR ARCHAEOLOGICAL SIGNIFICANCE

¹³C/¹²C and ¹⁸O/¹⁶O ratios have been measured for 42 marbles from the main quarry localities of archaeological interest of Western Anatolia (Marmara, Ephesos, Aphrodisias, Denizli and Afyon) in order to test the possibility of isotopically characterizing ancient marbles from this region. The various groups of samples are not clearly distinguishable on a δ¹³C-δ¹⁸O diagram. However, if only white or slightly coloured samples are considered, the isotopic method appears to be much more selective.     

LEAD ISOTOPE ANALYSES OF ISLAMIC POTTERY GLAZES FROM FUSTAT,EGYPT*

Lead isotope analyses have been undertaken on a group of Islamic lead‐glazed pottery artefacts from Fustat, Egypt, spanning the period from the eighth to the 14th century ad , that had previously been the subject of a comprehensive typological, chronological, petrographic and technological study. Comparison of the lead isotope ratios for the glazes with those for lead ores from Egypt, Iran, Tunisia, Anatolia, Greece, Sardinia and Spain provided information on the possible sources of the lead used in the production of the glazes. The results show that the lead used in glaze production by the Islamic potters at Fustat was most probably obtained from distant ore sources in Iran or Tunisia, Sardinia, Spain and the Taurus Mountains. Different ore sources were favoured in different periods and, to a limited extent, for different types of pottery, but at no time did the Fustat potters use the potentially more accessible Egyptian ore sources.     

STATISTICAL EVALUATION OF THE PRESENTLY ACCUMULATED LEAD ISOTOPE DATA FROM ANATOLIA AND SURROUNDING REGIONS

Several hundred new stable lead isotope ratio determinations of ore and slag specimens from ancient mining sites throughout Anatolia and of samples of artefacts of the Chalcolithic, Bronze Age and Early Iron Age from museum collections in Turkey and the United States have been combined with the accumulated published isotope determinations of such specimens from throughout the eastern Mediterranean and Aegean regions to form a data base of nearly 1000 analyses. It is the purpose of this paper to evaluate the practical effectiveness of using this now extensive data base to discriminate between the many sources of metals throughout this region and to propose methods to enhance this discrimination. By using the full three-dimensional isotopic data in multivariate statistical treatments and by separating isotopically resolvable source groups within some of the source areas and isolating statistically outlying specimens from them, it has been possible to characterize some ore sources more precisely and compactly and thereby achieve better resolution between ore sources. It has also been possible to isolate isotopically compatible artefact groups which possibly relate to ore sources that, as yet, have not been well defined by isotopic analysis.     

LEAD ISOTOPE ANALYSIS OF TANG SANCAI POTTERY GLAZES FROM GONGYI KILN,HENAN PROVINCE AND HUANGBAO KILN,SHAANXI PROVINCE

Through the use of MC–ICP–MS, this study analyses the lead isotope ratios of 19 Tang Sancai pottery glazes unearthed from the Gongyi and Huangbao kiln sites. According to their different lead isotope ratios, the two kilns can be grouped separately. The research also suggests that the Gongyi and Huangbao kilns are independent production centres of Tang Sancai in the Tang Dynasty. The data from the Huangbao kiln indicates that the lead in the glazes originates from the Northern China geochemical province, while the data from Gongyi kiln suggests its source as the Yangtze geochemical province. Furthermore, the results obtained for the Tang Sancai pottery indicate that the lead sources for glaze making of these two kilns were very consistent, which suggests that lead isotope analysis could be a helpful method to identify the kilns producing Tang Sancai artefacts.     

IN VITRO DECOMPOSITION OF BONE COLLAGEN BY SOIL BACTERIA: THE IMPLICATIONS FOR STABLE ISOTOPE ANALYSIS IN ARCHAEOMETRY*

To understand biogenic collagen type I decomposition and to establish how diagenesis may bias archaeometric data, modern mammalian bone was inoculated with a selection of ubiquitous soil bacteria. The presence of exogenous microbial biomass in the inoculated specimens was then checked microscopically prior to collagen extraction. The experimentally degraded bone collagen showed altered amino acid compositions, attributable to the selective breakdown of certain amino acids by the bacteria. While both the bulk collagen extract and the single amino acids exhibited shifts to more negative δ¹³ C-values, enrichment was recorded for general δ¹³ N, and a depletion trend relative to unaltered collagen was observed for individual amino acid δ¹³ N. One explanation for the enrichment of the global δ¹⁵N-values is cleavage of peptide bonds, which leaves ¹⁵ N within the substrate, while the change of ¹³C is mostly due to the altered amino acid composition. On the other hand, possible repolymerization of cleavage products under experimental conditions may also be responsible for the depletion trend of individual amino acid δ¹³C- and δ¹⁵ N-values. This paper discusses the results as a basis for the development of a method for the reconstruction of the isotopic abundance of the original collagen, using the amino acid composition of the degraded product, the contribution of individual amino acids to its global δ-values and of isotope discriminations implied in the microbial decomposition.     

EARLY BRONZE AGE METAL TRADE IN THE EASTERN MEDITERRANEAN. NEW COMPOSITIONAL AND LEAD ISOTOPE EVIDENCE FROM CYPRUS

Summary.   This paper presents the results of chemical and lead isotope analyses of 17 Early and Middle Bronze Age artefacts from Cyprus. These suggest that a number of objects are of non-Cypriot copper and lead to the identification of several as imports, a new explanation for some artefact types as ingots and a discussion of the nature of deposits at the key Cypriot site of Vasilia. This in turn allows a reconsideration of the role of Cyprus in an Aegean/eastern Mediterranean metals trade in the early years of the second half of the third millennium BC and of the development of metalworking on the island.     

CARBON ISOTOPE RATIOS IN PALAEODIET: LACK OF AGE OR SEX EFFECT

Palaeodiet of humans can be determined using stable carbon isotope ratios of bone collagen. Differences in δ¹³C-values between individuals in a population may be due to real differences in diet, or alternatively, they could be due to age- or sex-dependent differences in the physiologically controlled fractionation of carbon isotopes between food and collagen. The dependence of this fractionation on age and sex was tested in a study of 50 individuals of differing ages from a prehistoric population of bison hunters. The total variation in δ¹³C for bone collagen was found to be ± 0.3‰, indicating that variations larger than this, observed in other populations, are due to real dietary differences between individuals.     

STABLE CARBON ISOTOPE MEASUREMENTS OF THE CARBOXYL CARBONS IN BONE COLLAGEN*

In order to explore the possibility that intramolecular differences in the δ¹³C value of bone collagen can provide useful infomation for isotopic dietary analysis, a method for reliably measuring the δ¹³C value of the peptide-bonded carboxyl carbons in collagen was developed and applied to a wide range of modem and ancient species, including humans. Carboxyl carbons were selectively removed as CO₂ by decarboxylation of collagen hydrolysates with ninhydrin (2,2-dihydroxy-l,3-indanedione). Carboxyl carbons were usually isotopically heavier than the total carbon in the collagen, with differences ranging from -0.9 to 4.0%c. Animals at higher trophic levels and with more positive δ¹⁵N values usually had smaller differences than the lower animals while humans had the largest range, reflecting their larger range of diets.     

TECHNOLOGY AND PROVENANCE OF A COLLECTION OF ISLAMIC COPPER‐BASED OBJECTS AS FOUND BY CHEMICAL AND LEAD ISOTOPE ANALYSIS*

Chemical and lead isotope analyses were utilized to determine the composition, technology and origin of a collection of Islamic copper‐based objects found in Jordan. The atomic absorption spectrometry results show that the objects were made of different types of copper‐base alloys that contain various amounts of zinc, tin and lead. The use of brass, highly leaded brass and quaternary alloys of Cu‐Zn‐Sn‐Pb in the manufacture of everyday, household objects strongly points to Islamic traditions. The lead isotope compositions of the objects match very well that of the copper ore mined from the Dolomite‐Limestone‐Shale unit of the Arabah copper mines.     

LEAD ISOTOPE ANALYSES OF BRONZE AGE COPPER‐BASE ARTEFACTS FROM AL‐MIDAMMAN,YEMEN: TOWARDS THE IDENTIFICATION OF AN INDIGENOUS METAL PRODUCTION AND EXCHANGE SYSTEM IN THE SOUTHERN RED SEA REGION*

The results of the lead isotope analysis (LIA) of 15 copper‐base artefacts from the Bronze Age site of al‐Midamman, Yemen, are reported. The LIA data suggest the existence of an indigenous Bronze Age metal production and exchange system centred on the southern Red Sea region, distinct from those in neighbouring regions of Arabia and the Levant. These preliminary results are highly significant for the archaeology of the region, suggesting that local prehistoric copper extraction sites have thus far gone unrecorded, and highlighting the need for systematic archaeometallurgical fieldwork programmes in the countries surrounding the southern Red Sea.