Exploring Geographic Origins at Cahuachi using Stable Isotopic Analysis of Archaeological Human Tissues and Modern Environmental Waters

In this study, we used oxygen‐ and hydrogen‐isotope data from human bone (δ¹⁸O) and modern environmental water samples (δ¹⁸O and δD) to investigate geographic origins of individuals buried at Cahuachi, a ceremonial centre in the Nasca region of Peru (c.AD1‐1000). Our objective was to characterise the natural variation in water stable isotopic composition in the Rio Grande de Nasca drainage, and then to use these data to better infer place of origin for 30 adults interred at Cahuachi. Using the δ¹⁸O and δD values of 63 modern environmental water samples, it was possible to differentiate among the northern and southern river middle valleys, and to infer the isotopic composition of drinking water at higher elevations. Over half of the individuals included in this study had drinking water oxygen‐isotope compositions consistent with places of origin away from Cahuachi during the last 10 to 25 years of life, perhaps in the northern river middle valleys or in the upper valleys/sierra. The environmental water stable isotopic baseline developed in this study enabled a better understanding of the natural variation of waters in the Rio Grande de Nasca drainage. As a result, it was possible to assess the geographic range of place of origin for these individuals with greater certainty. Taken together, these data support the idea of Cahuachi as a place of both local and regional significance, with individuals from distant parts of the Rio Grande de Nasca drainage travelling to and/or transporting the dead to the site for death or burial. Copyright © 2011 John Wiley & Sons, Ltd.     

The consequences of Wari contact in the Nasca region during the Middle Horizon: archaeological,skeletal, and isotopic evidence

During the Middle Horizon (AD 650–1000), the Wari polity expanded its sphere of control in various regions of the Andes, including Nasca on the south coast of Peru. The nature of the interaction between Wari and local communities varied. This study explores the consequences of Wari contact in the Nasca region at the site of La Tiza, which includes individuals dated to the Early Intermediate, Middle Horizon, and Late Intermediate periods. Using evidence for burial ritual along with demographic, paleopathological and isotopic data, population composition, mobility, diet, and health are investigated. δ¹³C data indicate a relatively stable diet through time at La Tiza with evidence for continued maize consumption, and paleopathological results indicate health problems associated with this type of diet. δ¹⁸O and ⁸⁷Sr/⁸⁶Sr data suggest that most of the individuals buried at La Tiza were local to the area. However, two female adults from the Middle Horizon burials are characterized as nonlocal based on δ¹⁸O and ⁸⁷Sr/⁸⁶Sr values and several individuals overlap with the ⁸⁷Sr/⁸⁶Sr local range for the Wari heartland. In conjunction with the use of new tomb types during this period these results highlight the ideological and populational changes occurring with Wari contact at La Tiza.     

Identifying locals, migrants, and captives in the Wari Heartland: A bioarchaeological and biogeochemical study of human remains from Conchopata, Peru

The site of Conchopata in the central Peruvian Andes was the secondary center in the heartland of the Wari Empire (AD 600–1000), and in this study we examine whether this urban locale was populated by locals, voluntary migrants from distant regions, and/or captives who were forcibly brought to Conchopata. We examine radiogenic strontium isotope ratios from 72 dental enamel and bone samples representing 31 formal burials and 18 human trophy heads to distinguish between locals and non-locals, and we examine skeletal and archaeological data to establish whether non-local persons were voluntary migrants or captives. We also describe a new, straightforward technique in the evaluation of radiogenic strontium isotope ratios to assist in detecting non-locals when large datasets are available.Results show that natal Conchopata inhabitants should exhibit radiogenic strontium isotope ratios that range from ⁸⁷Sr/⁸⁶Sr = 0.70548 to ⁸⁷Sr/⁸⁶Sr = 0.70610. Thus, among the 31 burials, 29 exhibit local values, suggesting that Conchopata was not a cosmopolitan center to which numerous foreigners migrated; rather, it was populated by local peoples, likely the descendants of the preceding Huarpa culture. The two individuals with non-local radiogenic strontium isotope ratios are an infant and a 17–22 years old female. The archaeological context suggests that the female may have been taken captive for subsequent sacrifice, as she was interred in front of the ritual D-shaped structure in which decapitated human heads (trophy heads) and sacrificed camelids were deposited. Among the 18 trophy heads sampled, 14 have non-local values, confirming previous studies of smaller samples that suggested that Wari warriors travelled to other locales and took captives—both adults and children—for subsequent transformation into trophy heads. Additional analyses of bone-tooth pairs from a subsample (12 burials and six trophy heads) shows that the burial group was much more sedentary (homogenous radiogenic strontium isotope ratios in bones and teeth) and the trophy head individuals were much more mobile (heterogenous radiogenic strontium isotope ratios in bones and teeth). Overall, the multiple lines of evidence support the notion that the Wari Empire occasionally used militaristic means, combined with elaborate ritualism, to subjugate other populations, a tactic that may have helped Wari establish and maintain control in particular regions in the Andes.     

A compositional perspective on the origins of the “Nasca cult” at Cahuachi

We provide a compositional perspective on the origins of the Cahuachi cult in Nasca, south coast of Peru. Instrumental Neutron Activation Analysis of ceramics from the Formative site of La Puntilla demonstrate that a small group of pottery known as Nasca 1 blackwares are compositionally consistent with Early Nasca polychromes originating at Cahuachi. These data suggest that the patterns of pilgrimage and group ceremonies exhibited at Cahuachi during Early Nasca began at least in the proto-Nasca phase of Nasca 1 during the Formative. We use these data to further document the Paracas to Nasca transition, a complex and dynamic period in south coastal prehistory.     

Refining oxygen isotope analysis in the Nasca region of Peru: An investigation of water sources and archaeological samples

The development of complex societies, irrigation agriculture and sociopolitical transitions are of interest to researchers working in the Nasca region on the south coast of Peru. Occupied for thousands of years, many questions regarding the circumstances of these changes in the area are being investigated. Oxygen isotope analysis provides a method for exploring residential mobility of past peoples during these transitions. This study presents new δ¹⁸O data from water sources that would have been used by the ancient inhabitants, providing important information regarding the oxygen isotope variability in the region and the necessary baseline data for migration studies in this region. Our results suggest that the isotopic composition of water sources in the Nasca region is not highly variable. In addition, archaeological human tooth enamel samples from the sites of La Tiza and Pajonal Alto are analysed. The δ¹⁸O_c results of the human enamel samples confirm the local nature of the burial population, as suggested by previous strontium isotope analysis (⁸⁷Sr/⁸⁶Sr). Copyright © 2010 John Wiley & Sons, Ltd. This article was published online on 13 January 2010. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected 15 January 2010.     

Introducing δSr analysis in archaeology: a demonstration of the utility of strontium isotope fractionation in paleodietary studies

Isotopic methods are widely used in archaeology to investigate paleodiet. Here, we present a new method to identify trophic level in archaeological human populations and to investigate paleodiet. We demonstrate that strontium isotope compositions (reported as δ^88/86Sr) vary in a mass-dependent manner with increasing trophic level and can elucidate paleodiet in archaeological human populations. We present new mass-dependent strontium isotope data from tooth enamel and bone from individuals buried during the Late Intermediate Period (c. AD 1000–1300) in the large cemeteries of Chiribaya Alta, Chiribaya Baja, San Gerónimo, and El Yaral in the Ilo and Moquegua Valleys of southern Peru. We compare these data to radiogenic strontium isotope data (⁸⁷Sr/⁸⁶Sr) and light stable isotope data (δ¹⁵N_col and δ¹³C_col) from the same individuals to investigate geologic variability in strontium sources as well as marine food consumption among the Chiribaya. Our results demonstrate the utility of measurements of strontium isotope fractionation as a new tool for archaeological investigation of paleodiet. Importantly, this new technique can be used to generate paleodietary (δ^88/86Sr) and paleomobility (⁸⁷Sr/⁸⁶Sr) data from the same specimen, minimizing destructive analyses of invaluable archaeological material, and provides a new way to examine paleodiet through hydroxyapatite, which is particularly important when collagen is poorly preserved.     

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.     

Reconstructing Middle Horizon mobility patterns on the coast of Peru through strontium isotope analysis

The pre-Columbian coastal site of Ancón, Peru frequently has been interpreted as an important outpost of the highland Wari Empire, inhabited by individuals from the sierra and the coast. In order to test this hypothesis, bone–tooth pairs from 35 Middle Horizon (550 AD–1000 AD) Ancón skeletons were analyzed for strontium isotopes, which vary by geologic provenance. Results indicate that 34 of the 35 individuals have ⁸⁷Sr/⁸⁶Sr enamel and bone values higher than Ancón's biologically available strontium isotope range. Nitrogen and carbon isotope data from a subset of the Ancón skeletons suggest that the higher than expected ⁸⁷Sr/⁸⁶Sr values among the Ancón sample likely reflects a diet rich in marine resources rather than migratory activity, and highlight the need to use multiple lines of evidence to track residence change at sites where individuals relied on resources other than locally grown terrestrial foods. The one remaining individual, a young female of elite status, has an enamel strontium isotope signature much lower than the available data for local fauna and soil indicating that she was not raised locally. Her enamel ⁸⁷Sr/⁸⁶Sr ratio fits well within the range of strontium isotope values established for the inland Wari site of Conchopata [Tung, T.A., Knudson, K.J. Social identities and geographical origins of Wari trophy heads from Conchopata, Peru. Current Anthropology, in press.], and suggests that highland, Wari immigrants may have been present at Ancón during the Middle Horizon.     

Dietary shifting in the Nasca Region as inferred from the carbon- and nitrogen-isotope compositions of archaeological hair and bone

The topography of the Andean Region results in short travelling distances among ecologically distinct production zones. As such, it is possible to infer relative changes in residence based on the spatial variability in the isotopic composition of food resources. Here, we determine long-term diet through carbon- and nitrogen-isotope analysis of bone collagen for twenty-nine individuals from Cahuachi, an important ceremonial centre in the Nasca Region. We also reconstruct the temporal sequence of change in dietary isotopic compositions along hair samples for seventeen individuals buried at Cahuachi and the neighbouring site of Huaca del Loro.     

Human Response to Climate Change during the Umm an‐Nar/Wadi Suq Transition in the United Arab Emirates

Stable oxygen isotope ratios in archaeological human dental enamel represent an under‐utilised tool in the examination of changing climatic patterns in the ancient world. In the Oman Peninsula at the end of the third millennium bc , rapid aridification was accompanied by a breakdown in interregional trade relations; however, the human response to these changes is poorly understood. At the Bronze Age necropolis at Shimal in the United Arab Emirates, dental enamel from individuals interred in both Umm an‐Nar (ca 2700–2000 bc ) and Wadi Suq (ca 2000–1300 bc ) tombs underwent oxygen, strontium and carbon isotope analyses to examine how local inhabitants of southeastern Arabia responded to both environmental and socioeconomic change. While individuals from Shimal exhibit a clear shift in mean δ¹⁸O_c(VPDB) values from the Umm an‐Nar (−3.5 ± 0.6‰, 1σ) to the Wadi Suq (−2.4 ± 0.9‰, 1σ), corresponding ⁸⁷Sr/⁸⁶Sr and δ¹³C_ap signatures display homogeneity indicative of continuity in Bronze Age lifeways. Together, these data highlight the ability of local communities to successfully adapt to their changing environs (in lieu of societal collapse or a shift to a more mobile lifestyle) in an effort to maintain their way of life. Copyright © 2014 John Wiley & Sons, Ltd.     

C4‐Plant Foraging in Northern Italy: Stable Isotopes,Sr/Ca and Ba/Ca Data of Human Osteological Samples from Roccapelago (16th–18th Centuries AD)

Human osteological samples (n = 23) taken from different anatomical parts of 11 individuals from the early modern (16th–18th century AD) site of Roccapelago (Modena, Italy) were systematically analysed for δ¹³C, δ¹⁵N and trace elements to investigate their diet. δ¹³C and δ¹⁵N correlate and show a high variability between individuals, attesting to the dietary contribution of C₄ plants. This is supported by pollen analysis of the burial site samples, which revealed the presence of maize. δ¹⁵N correlates with Sr/Ca, suggesting that the main protein source could have been milk and dairy. We therefore interpret the strong correlation between δ¹³C and δ¹⁵N as evidence for C₄‐plant foraging practice and the exploitation of livestock for meat and milk, combined with possible direct intake of C₄ plants. The Roccapelago site represents an important case study to track the evolution of the post‐medieval diet and the introduction of maize cultivation in southern Europe, as also attested by historical sources.     

Thermochemical and bacterial sulfate reduction in the Cambrian and Lower Ordovician carbonates in the Tazhong Area,Tarim Basin,NW China: evidence from fluid inclusions,C, S,and Sr isotopic data

Petrographic features, C, O, S, and Sr isotopes were determined, and fluid inclusions (FI) were analyzed on various stages of vug‐ and fracture‐fillings from the Cambrian and Lower Ordovician reservoirs in the Tazhong area, Tarim basin, NW China. The aim was to assess the origin of pyrite and anhydrite and the processes affecting sulfur during diagenesis of the carbonates. Pyrite from seven wells has δ³⁴S values from ?22‰ to +31‰. The pyrites with low δ³⁴S values from ?21.8‰ to ?12.3‰ were found close to fracture‐filling calcites with vapor‐liquid double‐phase aqueous fluid inclusions homogenization temperatures (FI‐Th) from 55.7 to 73.2°C, salinities from 1.4wt% to 6.59wt% NaCl equiv and δ¹³C values from ?2.3‰ to ?14.2‰, indicating an origin from bacterial sulfate reduction by organic matter. Other sulfides with heavier δ³⁴S values may have formed by thermochemical sulfate reduction (TSR) during two episodes. The earlier TSR in the Middle and Lower Cambrian resulted in pyrites and H₂S having δ³⁴S values from 30 to 33‰, close to those of bedded anhydrite and oilfield water (approximately 34‰). The later TSR is represented by calcites with δ¹³C values as light as ?17.7‰ and FI‐Th of about 120–145°C, and pyrite and H₂S with δ³⁴S values close to those of the Upper Cambrian burial‐diagenetic anhydrite (between +14.8‰ and +22.6‰). The values of the anhydrite are significantly lighter than contemporary seawater sulfates. This together with ⁸⁷Sr/⁸⁶Sr values of anhydrite and TSR calcites from 0.7091 to 0.7125 suggests a source from the underlying Ediacaran seawater sulfate and detrital Sr contribution.     

Diet and death in times of war: isotopic and osteological analysis of mummified human remains from southern Mongolia

This study presents the results of an isotopic analysis of nine naturally mummified individuals—three adults, two adolescents, one juvenile, and three infants—recovered from the Hets Mountain Cave site in southern Mongolia, where they had been secondarily deposited. All of the individuals show evidence of violent perimortem trauma, but no skeletal indicators of nutritional or disease-related stress. Multi-isotopic data (δ¹³C, δ¹⁵N, δ¹⁸O, ⁸⁷Sr/⁸⁶Sr, and ²⁰ⁿPb/²⁰⁴Pb) were characterized in multiple tissues from each individual when possible, in order to reconstruct diet composition and residential origin at different points in life. Specifically, δ¹³C and δ¹⁵N in bone carbonate and collagen (N = 8) and hair keratin (N = 4) were coupled with enamel carbonate δ¹⁸O and δ¹³C (N = 3) and enamel ⁸⁷Sr/⁸⁶Sr, and ²⁰ⁿPb/²⁰⁴Pb (N = 3) to assess diet and residential mobility in relation to skeletal indicators of health and trauma. Results are consistent with a persistence of mixed C₃/C₄ pastoral subsistence and general stability of diet composition over the life course, in contrast to contemporary accounts of widespread famine and a dependence on grains imported from China throughout the region. However, results also suggest that at least some individuals may have migrated to this region of southern Mongolia from elsewhere during life, meaning that their dietary isotopic profiles may not represent local subsistence patterns near the Hets Mountain Cave site. Overall, these results speak to the utility of life course oriented multi-isotopic analysis in complementing more top-down historical analyses in understanding variation in subsistence, nutrition, and migration in regions undergoing significant political and economic turmoil.     

Ceramic production in ancient Nasca: provenance analysis of pottery from the Early Nasca and Tiza cultures through INAA

We report the results of an instrumental neutron activation analysis (INAA) undertaken on a regional sample of pottery from the Southern Nasca Region. The samples included specimens primarily from the Early Nasca (ca. A.D. 1–450) and Tiza (ca. A.D. 1000–1476) cultures from a total of 16 different prehispanic sites. The results of the analysis demonstrate centralized production of Early Nasca polychromes and decentralized production of pottery from the Tiza culture. The results of this analysis confirm previous conclusions about the organization of these two indigenous cultures of the south coast of Peru and support the hypothesis of an excess production of polychromes at the ceremonial center Cahuachi for Early Nasca, and multiple centers of production for the Tiza culture.     

BRONZE AGE CHILDHOOD MIGRATION OF INDIVIDUALS NEAR STONEHENGE,REVEALED BY STRONTIUM AND OXYGEN ISOTOPE TOOTH ENAMEL ANALYSIS*

Contrasting lifestyles are recorded by the isotope composition of Bronze Age Beaker people (c. 2500–2000 bc ) from three burial sites (Boscombe Down, Normanton Down and the ditch around Stonehenge) at or near to the Stonehenge monument in Wiltshire, southern England. Seven individuals (three adults, a sub‐adult, two juveniles and an infant) were recovered from a single grave at Boscombe Down. Strontium and oxygen isotope analysis of tooth enamel from two teeth (a premolar and third molar) from each of three of the adults in this grave (referred to as Boscombe Bowmen) show that they had all shared a pattern of mobility and migration during their lives. The three adult males spent their early childhood (as represented by data from the premolar teeth) in an area with a radiogenic ⁸⁷Sr/⁸⁶Sr isotope signature of around 0.7135. They each then moved, during early adolescence (as represented by the third molar results), to a less radiogenic area, where they acquired an ⁸⁷Sr/⁸⁶Sr signature of around 0.7112. This implies that they must then have travelled to the Stonehenge area of Wiltshire at a later time in their lives. Wales provides the closest area with rocks that supply suitable ⁸⁷Sr/⁸⁶Sr ratios and δ¹⁸O isotope compositions for these individuals, although other areas of Palaeozoic rock, such as Scotland and parts of Europe, cannot be ruled out. Enamel from the two juveniles from the Boscombe Down burial yields ⁸⁷Sr/⁸⁶Sr ratios of 0.7098 and 0.7099, and strontium concentrations for both of 55 ppm. The very close match of the data for the two juveniles supports the possibility that they were raised in the same environment. The difference in strontium isotope data between the juveniles and three adult males described above shows that the children did not come from the same homeland as the adults with whom they share a grave. The two adult males from the single burials at Normanton Down, and from Stonehenge itself, had static lifestyles and show no evidence of migration, in contrast to the Boscombe Bowmen. Their oxygen and strontium data are consistent with a childhood in the Stonehenge area.     

Oxygen and strontium isotopes as provenance indicators of fish at archaeological sites: the case study of Sagalassos,SW Turkey

In this paper, we investigate the potential use of oxygen and strontium isotope ratios (δ¹⁸O_p and ⁸⁷Sr/⁸⁶Sr) measured in archaeological fish enamel as provenance indicators. δ¹⁸O_p and ⁸⁷Sr/⁸⁶Sr were measured in a suite of archaeological carp remains recovered from the Anatolian townsite of Sagalassos dated to the Early Byzantine period (AD 450–650) and compared to that of modern fish, river and lake waters from the Anatolian region. We used sequential leaches in weak acetic acid to remove diagenetic Sr from fossil tooth enamel, monitoring the effectiveness of this approach by measuring the Sr/Ca ratios of the leachates via an isotope dilution thermal ionization mass spectrometry method (ID-TIMS). δ¹⁸O_p values mostly excluded a riverine origin. ⁸⁷Sr/⁸⁶Sr ratios of one fish overlapped with the ⁸⁷Sr/⁸⁶Sr signatures of two lakes in the Anatolian region, and at least one lake (Gölcük) could be removed as a candidate owing to a very distinctive ⁸⁷Sr/⁸⁶Sr signature not found in any of the fish remains. Most of the tooth samples analyzed could not be assigned a precise geographical origin since the ⁸⁷Sr/⁸⁶Sr ratios measured in enamel did not match that of any of the local lakes selected as potential origin. This result suggests that carp may have originated from lakes that have not yet been sampled, although this conclusion is not supported by other archaeological evidence. Alternatively, the lack of correspondence between lakes and fish Sr isotope ratios highlights several possible sources of uncertainties including spatial heterogeneity in ⁸⁷Sr/⁸⁶Sr ratio within a lake, the contribution of dietary strontium to the ⁸⁷Sr/⁸⁶Sr ratio of fish tooth enamel, and post-mortem alteration of the tooth Sr isotope signal during fossilization. In spite of the high precision of the strontium isotope analyses and the wide range of variation in the surface waters of the Anatolian lakes and rivers, this method may remain limited to distinguishing between lakes situated in regions of bedrock of very distinct age and geology until these sources of uncertainty are more fully investigated.     

Fisherfolk and farmers: Carbon and nitrogen isotope evidence from Middle Horizon Ancón,Peru

This study investigates human dietary patterns and economic trends at the coastal site of Ancón, Peru during the Andean Middle Horizon (550AD –1000AD ) using stable isotopic data from 32 individuals buried at the site. δ¹³C and δ¹⁵N results from human bone collagen and δ¹³C from human tooth enamel and bone carbonate indicate that inhabitants consumed a mixed diet composed primarily of marine protein and C₄ resources, with only marginal reliance on C₃ foods. Over time, Ancóneros appear to have relied more heavily on C₄ resources, particularly maize, despite the fact that the crop could not have been grown locally. These results are notable given that C₃ rather than C₄ or marine foods dominate the site's archaeological record. These data suggest that Ancón's inhabitants either had access to more fertile land up‐valley where maize could be cultivated successfully or that they engaged in trade relationships with their valley neighbours. A third possibility is that increased maize consumption at Ancón during the Middle Horizon resulted from Wari imperial influence and interregional exchange. Comparisons of δ¹³C values in enamel and bone carbonate from Ancón individuals indicate that δ¹³C_{carb_enamel} values are significantly more positive than δ¹³C_{carb_bone} values. This suggests that the diets of young children were systematically enriched in ¹³C compared to that of adults, perhaps as a result of nursing activity and/or differential dietary practices among various age groups at the site. Copyright © 2009 John Wiley & Sons, Ltd.     

Fluid mixing induced by hydrothermal activity in the ordovician carbonates in Tarim Basin,China

Permian hydrothermal activity in the Tarim Basin may have been responsible for the invasion of hot brines into Ordovician carbonate reservoirs. Studies have been undertaken to explain the origin and geochemical characteristics of the diagenetic fluid present during this hydrothermal event although there is no consensus on it. We present a genetic model resulting from the study of δ¹³C, δ¹⁸O, δ³⁴S, and ⁸⁷Sr/⁸⁶Sr isotope values and fluid inclusions (FIs) from fracture‐ and vug‐filling calcite, saddle dolomite, fluorite, barite, quartz, and anhydrite from Ordovician outcrops in northwest (NW) Tarim Basin and subsurface cores in Central Tarim Basin. The presence of hydrothermal fluid was confirmed by minerals with fluid inclusion homogenization temperatures being >10°C higher than the paleo‐formation burial temperatures both in the NW Tarim and in the Central Tarim areas. The mixing of hot (>200°C), high‐salinity (>24 wt% NaCl), ⁸⁷Sr‐rich (up to 0.7104) hydrothermal fluid with cool (60–100°C), low‐salinity (0 to 3.5 wt% NaCl), also ⁸⁷Sr‐rich (up to 0.7010) meteoric water in the Ordovician unit was supported by the salinity of fluid inclusions, and δ¹³C, δ¹⁸O, and ⁸⁷Sr/⁸⁶Sr isotopic values of the diagenetic minerals. Up‐migrated hydrothermal fluids from the deeper Cambrian strata may have contributed to the hot brine with high sulfate concentrations which promoted thermochemical sulfate reduction (TSR) in the Ordovician, resulting in the formation of ¹²C‐rich (δ¹³C as low as ?13.8‰) calcite and ³⁴S‐rich (δ³⁴S values from 21.4‰ to 29.7‰) H₂S, pyrite, and elemental sulfur. Hydrothermal fluid mixing with fresh water in Ordovician strata in Tarim Basin was facilitated by deep‐seated faults and up‐reaching faults due to the pervasive Permian magmatic activity. Collectively, fluid mixing, hydrothermal dolomitization, TSR, and faulting may have locally dissolved the host carbonates and increased the reservoir porosity and permeability, which has significant implications for hydrocarbon exploration.     

Prehistoric migration at Nebira, South Coast of Papua New Guinea: New insights into interaction using isotope and trace element concentration analyses

Migration is a commonly used explanation for cultural change in world prehistory, and is also a central theme in the prehistory of the Pacific Islands. However it is rarely subject to direct archaeological research. This paper applies strontium and oxygen radiogenic/stable isotope (⁸⁷Sr/⁸⁶Sr, δ¹⁸O), and trace element concentration (Ba/Sr) analyses to 27 individuals buried at the archaeological site of Nebira (ca.720–300 BP), located inland on the South Coast of Papua New Guinea. The analyses seek to identify non-local individuals within the population and provide a more in-depth understanding about the social identity of the possible migrants in this community.The strontium isotope data indicates that five individuals were non-local to Nebira, having possibly come from a coastal location. Correlation with biological data, such as age and sex, also indicates that the pattern of migration at Nebira was not sex or age specific. The results support the archaeological findings that suggest the inhabitants from Nebira were in contact with coastal communities during a period in prehistory of increased cultural interaction. However, despite the considerable isotopic variation identified in the Nebira sample, it is also demonstrated that more research is needed to identify the possible origins of these non-local individuals.     

Development of successive karstic systems within the Baix Penedès Fault zone (onshore of the Valencia Trough,NW Mediterranean)

The Baix Penedès Fault zone records successive karstic systems. The outcrops studied correspond to different segments of the fault, which were temporarily connected and disconnected, allowing for different diagenetic processes to occur. The first karstic system affected the Mesozoic rocks due to subaerial exposure after Paleogene compression, an event characterized by widespread dissolution and the generation of vug and cavern porosity. The δ¹⁸O values of the dolomitic sediment filling the initial vuggy porosity are similar to those of the host dolomite, indicating that the sediment comes from the erosion and reworking of the host rock. The second karstic system is related to the upward propagation of the Baix Penedès Fault. This deformation was characterized by random‐fracture fabrics with dolomite cement and sediment. The stable isotopes values and Sr/Ca ratios of both the dolomite cement and sediments are similar to those of the host rock. In contrast, the more depleted δ¹³C values indicate the influence of soil‐derived CO₂ and the opening of the system to meteoric waters. During the third karstic event, the δ¹⁸O, δ¹³C, Sr/Ca ratios, and ⁸⁷Sr/⁸⁶Sr values of diagenetic cements suggest a marine signature, indicating that the karstic sediments were dolomitized under the influence of late Burdigalian‐Langhian marine waters. These marine waters were probably expelled from poorly buried sediments and circulated through faults producing dolomitization of the karstic sediments. A final karst system developed during a period of uplift and subaerial exposure. The δ¹⁸O values, the Mg/Ca and Sr/Ca ratios, and the high radiogenic values of the calcite cements formed during this period indicate precipitation from meteoric waters. The results of this study have implications for carbonate hydrocarbon reservoir analogs subject to karstic influence in the Valencia Trough and elsewhere.