Source of ore fluids at the Kalahari Goldridge deposit, Kraaipan greenstone belt, South Africa: evidence from Sr, C and O isotope signatures in carbonates

The Kalahari Goldridge deposit is located in the Archaean Kraaipan greenstone belt in the north-west province of South Africa. Gold mineralization in this deposit is hosted within banded iron formation which is flanked by a mafic schist in the footwall and clastic metasedimentary units in the hanging wall. Data from carbonate minerals from mineralized veins and bulk rock from the A and D zone ore bodies have helped to define the ultimate origin of the ore-forming fluids and their migration history. Carbon isotope ratios of carbonates from both the A and D zone ore bodies have tight clustering from −7.6 to −5.3‰ that indicates a unique origin for the ore-forming fluids associated with the mineralization at Kalahari Goldridge. The δ¹⁸O values of the carbonates have been influenced by temperature gradients and variable degrees of fluid–rock interaction promoting oxygen isotope exchange between ore fluid and host rocks. Minimum ⁸⁷Sr/⁸⁶Sr ratio values of 0.70354 in mineralized veins are most consistent with ore-forming fluids being relatively pristine with a mantle origin. Strontium and the corresponding ore-forming fluids were most likely derived from mantle-derived magmatic rocks probably represented by the meta-basaltic rocks that underlie the ferruginous package in the Kraaipan greenstone belt. Strontium isotopic composition of vein carbonates show considerable variation in ⁸⁷Sr/⁸⁶Sr ratios ranging from 0.70354 to 0.73914. This is consistent with an ore fluid composition that has been modified by the addition of radiogenic Sr possibly during passage of fluid through siliciclastic country rock concomitant with the observed hydrothermal alteration.     

Migration and Viking Dublin: paleomobility and paleodiet through isotopic analyses

During the early medieval period in Ireland, Dublin was established as the largest Viking settlement on the island in the ninth century AD. A previous biodistance study has suggested that the population of the town consisted of a polyethnic amalgam of immigrant and indigenous. In this study, we use biogeochemistry to investigate paleomobility and paleodiet in archeological human remains from the ninth to eleventh century levels at the sites at Fishamble Street II (National Museum of Ireland excavation number E172), Fishamble Street III (E190) and John’s Lane (E173), as well as twelfth-century remains from Wood Quay (E132). Through radiogenic strontium isotope, stable oxygen, carbon, and nitrogen isotope, and elemental concentration analyses, we investigate the origins of the individuals who lived and died in early and late Viking Dublin. Mean archaeological human enamel and bone isotope values from Dublin are ⁸⁷Sr/⁸⁶Sr = 0.70975 ± 0.00139 (2σ, n = 22), δ¹³C_{carbonate(V-PDB)} = −14.8‰ ± 0.8‰ (1σ, n = 12), and δ¹⁸O_{carbonate(V-PDB)} = −7.2‰ ± 1.0‰ (1σ, n = 12). Archaeological human bone samples exhibit mean δ¹³C_{collagen(V-PDB)} = −20.8‰ ± 0.5‰ (1σ, n = 12) and mean δ¹⁵N_{collagen(AIR)} = +10.0‰ ± 1.7‰ (1σ, n = 12). Comparing these data with archaeological faunal data from Dublin and published data from northern Europe, we argue that there are no clear immigrants from other parts of the North Atlantic, although there is one clear outlier in both origins and diet. Overall, the relative homogeneity in both paleomobility and paleodiet may support models of acculturation in Viking Dublin, rather than a high number of first-generation immigrants or continued migration from Scandinavia.     

Intrinsic or extrinsic population growth in Iron Age northeast Thailand? The evidence from isotopic analysis

Here we present strontium, carbon and oxygen isotope measurements from the tooth enamel of 34 adults from Noen U-Loke, an Iron Age site (c. 300BC–500AD) in the Upper Mun River Valley (UMRV), northeast Thailand. The Mun Valley is rich in archaeological sites from the Bronze Age to the Iron Age, with evidence for changes in social complexity, new technologies and population growth. Whether the population growth in the UMRV was intrinsic, as opposed to extrinsically due to immigration, is an unresolved question. Our results suggest low levels of long-distance immigration, with only three (two females, one male) of the thirty-four individuals as probable immigrants from outside the region. We discuss the implications of this result as a contribution to longer-term investigations of population growth, human mobility and fertility during this prehistoric period of substantial societal changes in mainland Southeast Asia.     

Immigration to Tikal,Guatemala: Evidence from stable strontium and oxygen isotopes

This paper presents strontium and oxygen isotopic measurements on archaeological human teeth from the ancient Maya city of Tikal, Guatemala, that illuminate the role that migration played in the history of the state. Stable strontium isotope ratios of human teeth parallel the bedrock geology of the location where foods were grown, while stable oxygen isotope ratios reflect the sources of water imbibed, and track geographic variation in the isotopic composition of rain water. Because tooth enamel forms during childhood and is not remodeled during life, we can identify foreign-born individuals at Tikal by their outlying strontium and oxygen isotope ratios. These data indicate that approximately 11–16% of the sampled Tikal skeletons spent their childhood at distant sites. Most of the migrant burials date from the Early Classic period and are high status contexts. Several royal burials demonstrate long distance movement of both males and females, and shed light on the identification of epigraphically-known individuals. Yet, both Early and Late Classic migrants are found in lower status domestic burials. Interaction with distant peers was important in the rise of the Tikal polity, however, immigration from all social tiers contributed to the city’s rapid population growth.     

Food for Rome: A stable isotope investigation of diet in the Imperial period (1st–3rd centuries AD)

During the Empire, the population of Rome was composed mostly of lower-class free citizens and slaves. Viewed from historical records, the Roman diet included primarily olives, wine, and wheat, but poor and enslaved Romans may have eaten whatever they were able to find and afford, leading to significant heterogeneity in the Roman diet. Previous carbon and nitrogen isotope analyses of skeletons from Imperial Italy have begun to reveal variation in diet, but little is known about what people ate in the capital city. This study complements previous work by adding new isotope data from human skeletons found in two Imperial-period (1st–3rd centuries AD) cemeteries in Rome. These data suggest that urban and suburban diets differed, most notably in the consumption of the C₄ grain millet. Comparing these new data with all published palaeodietary data from Imperial Italy demonstrates that significant variation existed in the diet of the common people.     

Investigating Identity and Life Histories: Isotopic Analysis and Historical Documentation of Slave Skeletons Found on the Cape Town Foreshore, South Africa

Isotopic analysis of skeletons excavated during the 1950s has confirmed that they are the remains of shipwreck victims: slaves on board the Portuguese slaving brig Pacquet Real when it sank on 18 May 1818. Twenty-five slaves drowned and the remaining 133 became Prize Negroes at the Cape. The isotopic signatures are consistent with values expected for people living in an African village eating a terrestrially based diet. Analyses of different skeletal elements, i.e., teeth, long bone, and rib, are shown to be a valuable tool in tracing change or consistency in diet during a person's life, because different skeletal elements form at different stages of life and, subsequently, remodel at different rates. A comparison of isotope ratios from different skeletal elements indicates a change in diet in all these individuals, probably coincident with their enslavement. Variation between individuals in the isotopic composition of diets eaten early in life is sufficiently large to deduce heterogeneous origins for the group.     

Syntectonic infiltration by meteoric waters along the Sevier thrust front,southwest Montana

Structural, petrographic, and isotopic data for calcite veins and carbonate host‐rocks from the Sevier thrust front of SW Montana record syntectonic infiltration by H₂O‐rich fluids with meteoric oxygen isotope compositions. Multiple generations of calcite veins record protracted fluid flow associated with regional Cretaceous contraction and subsequent Eocene extension. Vein mineralization occurred during single and multiple mineralization events, at times under elevated fluid pressures. Low salinity (T_m = ?0.6°C to +3.6°C, as NaCl equivalent salinities) and low temperature (estimated 50–80°C for Cretaceous veins, 60–80°C for Eocene veins) fluids interacted with wall‐rock carbonates at shallow depths (3–4 km in the Cretaceous, 2–3 km in the Eocene) during deformation. Shear and extensional veins of all ages show significant intra‐ and inter‐vein variation in δ¹⁸O and δ¹³C. Carbonate host‐rocks have a mean δ¹⁸O_V‐SMOW value of +22.2 ± 3‰ (1σ), and both the Cretaceous veins and Eocene veins have δ¹⁸O ranging from values similar to those of the host‐rocks to as low as +5 to +6‰. The variation in vein δ¹³C_V‐PDB of ?1 to approximately +6‰ is attributed to original stratigraphic variation and C isotope exchange with hydrocarbons. Using the estimated temperature ranges for vein formation, fluid (as H₂O) δ¹⁸O calculated from Cretaceous vein compositions for the Tendoy and Four Eyes Canyon thrust sheets are ?18.5 to ?12.5‰. For the Eocene veins within the Four Eyes Canyon thrust sheet, calculated H₂O δ¹⁸O values are ?16.3 to ?13.5‰. Fluid–rock exchange was localized along fractures and was likely coincident with hydrocarbon migration. Paleotemperature determinations and stable isotope data for veins are consistent with the infiltration of the foreland thrust sheets by meteoric waters, throughout both Sevier orogenesis and subsequent orogenic collapse. The cessation of the Sevier orogeny was coincident with an evolving paleogeographic landscape associated with the retreat of the Western Interior Seaway and the emergence of the thrust front and foreland basin. Meteoric waters penetrated the foreland carbonate thrust sheets of the Sevier orogeny utilizing an evolving mesoscopic fracture network, which was kinematically related to regional thrust structures. The uncertainty in the temperature estimates for the Cretaceous and Eocene vein formation prevents a more detailed assessment of the temporal evolution in meteoric water δ¹⁸O related to changing paleogeography. Meteoric water‐influenced δ¹⁸O values calculated here for Cretaceous to Eocene vein‐forming fluids are similar to those previously proposed for surface waters in the Eocene, and those observed for modern‐day precipitation, in this part of the Idaho‐Montana thrust belt.     

Chemical and lead isotope analysis of some lead-barium glass wares from the Warring States Period,unearthed from Chu tombs in Changde City,Hunan Province,China

In the context of the present study, we have conducted chemical and lead isotope analyses on twelve ancient glass samples unearthed from Chu tombs in Changde City, Hunan Province. The results of the chemical analysis of these samples show that all samples are PbO–BaO–SiO₂ glasses, thus indicating that they are all traditional ancient Chinese glasses. The chemical results also suggest that all Bi wares may either share a common source or were produced according to similar recipes. In turn, the eye beads are different from the Bi wares for their distinct chemical composition. The chemical results indicate that silica, lead-bearing material, barium-bearing material, and sodium/lime-bearing material are the main independent components of the raw materials employed in the production of these glass wares.     

Seasonal stability in Late Holocene shellfish harvesting on the central California coast

Oxygen isotope determinations from 92 California mussel (Mytilus californianus) shells from ten archaeological sites in central coastal California show relatively stable seasonal harvesting patterns between 3600 CAL BP and historic contact (AD 1769). Coastal occupants harvested mussels nearly year-round and seem to have occupied individual residential bases throughout the seasonal cycle. Interior groups returned with mussels from the coast mostly in the spring and early summer, but almost never in the late summer/early fall when nut crops were harvested. These findings suggest two inter-dependent groups with distinct seasonal settlement strategies: inland people, reliant on acorns and other nut crops harvested in the fall, and coastal inhabitants who were less involved with acorns. This pattern is supported by accounts recorded by the first Spanish explorers in AD 1769. While some interior groups may have been seasonally migrating “collectors,” coastal populations were less mobile, inhabiting individual residential sites throughout the year, albeit not necessarily on a permanent basis. These findings highlight the strong influence of coastal environments and resources on hunter-gatherer mobility.     

Stable isotope insights (δ18O, δ13C) into cattle and sheep husbandry at Bercy (Paris,France, 4th millennium BC): birth seasonality and winter leaf foddering

Abstract

Bercy is a prehistoric village sited by the Seine river (Paris, France), whose main period of occupation was dated to the very beginning of the 4th millennium BC. The animal subsistence economy relied heavily on cattle husbandry, complemented by other species including sheep. Cattle and sheep isotopic history (δ¹³C, δ¹⁸O) was investigated at the seasonal scale, through sequential sampling in tooth enamel, providing new insights into seasonality of birth and diet. Sheep were lambing in mid-spring, only slightly later than expected from what is observed nowadays in temperate Europe at similar latitude. Cattle were born over a period spanning approximately six months, which was an unexpected result compared with a two to three months calving period in free-ranging cattle populations. The extension of the calving period might have been related to seasonal food supplementation. Some cattle and some sheep fed on a ¹³C-depleted resource in winter, potentially leafy fodder. A direct consequence of an extended calving period would be the availability of cow milk, which would have covered the whole year at Bercy. This is important information in a context where the exploitation of cattle milk by the human community was highly suspected from the demographic management of the herd.     

A 2500‐year record of marine resource use on Ulong Island,Republic of Palau

The paper reports fish bone and shellfish assemblages from Ulong Island in the Rock Islands of Palau, western Micronesia dating from ∼3100 to 500 BP . Use of marine resources in early prehistory appears to have been highly localised with increasing capture of outer‐reef/pelagic taxa including shark and tuna after 1000 BP . Local stocks of large Tridacnids were depleted during initial human use of Ulong Island, and there is a size decrease in Scarus sp. remains consistent with pressure on the inshore fishery, especially after establishment of permanent stonework villages in late prehistory. Comparison of archaeological assemblages of fish bone from other Rock Islands dated to after 2000 BP indicate that the captured fish species and major capture methods differ between sites and likely reflect local marine environments at each location. Copyright © 2010 John Wiley & Sons, Ltd.     

甘肃酒泉西沟村魏晋墓铜甑釜残留物的脂质分析

残留物分析可为器物用途提供直接证据。铜甗是古代重要的炊具之一,其用途在文献上有较多记载,但残留物分析甚少。甘肃酒泉西沟村魏晋墓M5出土铜甑釜(分体甗)下半部分的釜内存有一些白色膏状残留物,为了解其生物来源和该器物的功能,本工作利用红外光谱、脂质分析及单体脂肪酸稳定碳同位素等方法进行了综合分析。结果表明,这些白色膏状残留物应为反刍动物油脂,推测是蒸制铜甑中的牛肉或羊肉时渗流下来而成,这为该釜甑组合作为炊蒸器用于加工肉食提供了有力证据。鉴于墓M5具有浓郁的游牧文化风格,而铜甗是典型的中原汉人炊具,这也反映了魏晋时期当地汉人与北方游牧民族在饮食文化方面的交流与融合。