Strontium Isotope Values Research Articles

Human Mobility in NW Iran During the Early Iron Age (c. 1250–850 bce): The Strontium Isotope Evidence From Masjed‐e Kabud Cemetery

ABSTRACTThe transition from the Bronze Age to the Iron Age is one of the most discussed topics in the archaeology of Iran. This includes the processes that led to the formation of the Mannaean Kingdom in the northwestern part of the country, which is considered a forerunner of the famous Median Empire. Here, we investigate the pattern of migration during the four centuries preceding the establishment of the Mannaean Kingdom. The 87Sr/86Sr values were measured in enamel of early developing permanent teeth (first molars and incisors) in a sample of 28 individuals of both sexes from Masjed‐e Kabud cemetery (modern Tabriz). Only two individuals have non‐local strontium isotope values; however, they might have been inhabitants of the region located just a few kilometers south of the cemetery. No evidence of long‐distance migration was identified, suggesting that the establishment of the early states in this region was not a consequence of migration, but rather of social development in the local population.

Early diagenetic mobilization of rare earth elements and implications for the Ce anomaly as a redox proxy

The Rare Earth Elements (REE) archived in carbonate rocks retain a wealth of information on paleo-seawater chemistry and local-regional redox conditions. However, interpretations are often ambiguous due to the potential for REE remobilization in marine environments. In this regard, many carbonate rocks that retain primary seawater isotopic signatures exhibit non-seawater-like REE patterns, implying either unusual REE behaviour in seawater or diagenetic overprinting of otherwise well-preserved rock samples. Here, we apply sequential leaching to constrain the possible effects of different REE-bearing phases on measured carbonate REE patterns in order to address this quandary. Our results show that the exchangeable phase contains negligible REE, but could be an important host phase for other elements such as Sr, Ba and K. The acidified hydroxylamine hydrochloride leach is shown here not only to dissolve Fe–Mn oxides but also phosphate minerals, which induces middle REE enrichment in corresponding leachates of dolostone samples in our study. The demonstrable Fe–Mn oxide phase in limestone samples is characterized by middle and/or light REE enrichment and positive Eu anomalies, which are attributed to hydrothermal processes and continuing exchange with marine fluids after initial precipitation. The non-seawater-like REE patterns observed in the carbonate phase of otherwise well-preserved limestones resemble those of the co-existing Fe–Mn oxide fraction, and are interpreted to reflect the dissolution of REE carrier phases during early diagenesis. This view is supported by fluid-rock interaction modelling, which shows how REE can be mobilized at relatively low fluid/rock ratios in shallow porewaters. Non-seawater-like REE patterns may therefore be caused by the incorporation of REE from shallow porewaters before final lithification due to an elevated flux of particulate REE carrier phases, e.g. Fe–Mn oxides and organic matter, to the seafloor. In spite of the sensitivity of carbonate REE patterns to early diagenetic exchange, the co-occurrence of non-seawater-like patterns with primary strontium and carbon isotope values suggests that REE should not be viewed as a general indicator for the preservation of other geochemical proxies. Importantly, Ce anomalies of the carbonate phase will also be affected by porewaters, masking primary seawater values. Our results favour a reevaluation of redox interpretations by taking into account REE patterns as a whole.

Strontium isotope analysis of the Xiongnu nobles and their followers in Central Mongolia

As the first provenance study focusing on Xiongnu nobles and their followers, this study analyzed eleven human and four animal remains from the Gol Mod 2 cemetery in western Mongolia for strontium isotope ratios. The results suggest that two of the three nobles had lived in the Khanuy valley for an extended period of time, and one had lived elsewhere but was buried at the same cemetery as were the other nobles. These Xiongnu nobles might have migrated in the grassland, but the Khanuy valley and the Gol Mod 2 site surely played an irreplaceable role for them, providing valuable information for the investigation of the Xiongnu political center. A number of the followers did not grow up locally but were chosen to follow the nobles and lived in or close to the valley during their later lives. Furthermore, strontium isotope values and dietary features together confirmed that the human skeleton in G2T189 belonged to the tomb owner rather than a buried intruder. This study is a reminder that some traditional methods used to determine the local strontium isotopic range for a site are not suitable when the studied human individuals did not live a sedentary lifestyle or their social roles evidently varied.

Rare earth elemental and Sr isotopic evidence for seawater intrusion event of the Songliao Basin 91 million years ago

Petrogenesis of lacustrine dolostone is closely related with paleo-lake water conditions. Here we report the high spatial-resolution petrographic and geochemical results of a lacustrine dolomite nodule from the Qingshankou Formation, the Songliao Basin. Sedimentary and elemental signatures confirm the protogenetic origin of this nodule and its effectiveness in recording geochemical characteristics of paleo-lake water during dolomitization. The low Y/Ho ratios, middle rare earth element (MREE) enrichment and subtle positive Eu anomalies within the nodule indicate a fresh water source. However, the Sr isotope values in the core of the nodule (0.7076–0.7080) are close to contemporaneous seawater (0.7074), yet different from the modern river (0.7120) and the host black shale (0.7100). On the premise of excluding the influence of hydrothermal fluids, the significantly low strontium isotope values of the lacustrine dolomite might be caused by seawater interference during dolomitization. Our findings demonstrate that lacustrine dolomite within black shales is not only a faithful tracer of diagenetic water environment, but also a novel and easily identified mineralogical evidence for episodic seawater intrusion event (91 Ma) in the Songliao Basin, which supplements other paleontological and geochemical evidence.

Ceramics and seasonality: Mobile lifeways and ceramic production of the Catacomb population, lower don Eastern Europe

Located on the plains of southern Russia, the Sal-Manych steppe has been exploited by mobile pastoralists since at least the Eneolithic. Recent investigations into temporary settlement in the region have uncovered a number of pastoral camps dating to the second half of the third millennium BCE, locally associated with the Catacomb culture. According to seasonality research, camps at balka Volochaika and Chikalda were occupied in the summer-early autumn seasons, while stable carbon, nitrogen, and strontium isotope values of faunal remains on site suggest that domesticated herds grazed on pastures outside the Sal-Manych region in the winter and spring. However, beyond routine herding activities, the everyday economy should be understood as also including the production of everyday technologies such as ceramics. Using portable X-ray fluorescence (pXRF) paired with macroscopic technological analysis, this research indicates that ceramic production strategies at these camps entailed the production and replacement as needed of ceramic vessels at temporary camps located on the Sal-Manych steppe, involving at least short distance curation. Ritual vessels deposited at regional kurgans mainly cluster geochemically with ceramic materials from the Lower Don and North Caucasus, rather than nearby camps.

Finding Mycenaeans in Minoan Crete? Isotope and DNA analysis of human mobility in Bronze Age Crete

We undertook a large-scale study of Neolithic and Bronze Age human mobility on Crete using biomolecular methods (isotope analysis, DNA), with a particular focus on sites dating to the Late Bronze Age (‘Late Minoan’) period. We measured the strontium and sulphur isotope values of animal remains from archaeological sites around the island of Crete to determine the local baseline values. We then measured the strontium and sulphur values of humans from Late Neolithic and Bronze Age sites. Our results indicate that most of the humans have sulphur and strontium isotope values consistent with being local to Crete, showing no evidence for a wide-scale movement of people from the Greek mainland or other areas away from Crete in these time periods. However, we found four individuals from the late Bronze Age (Late Minoan III) cemetery of Armenoi with sulphur isotope values not typically found in Crete and are instead consistent with an origin elsewhere. This cemetery at Armenoi also has one of only a few examples of the newly adopted Mycenaean Linear B script on Crete found outside of the palace sites, pointing to an influence (trade and possible migration) from the mainland, which may then be the place of origin of these four individuals. DNA (mtDNA) studies of eight Late Bronze Age individuals from Armenoi have results consistent with people living in Aegean region at this time and cannot be used to distinguish between individuals from Crete (‘Minoans’) and the Greek mainland [‘Mycenaeans’]).

Putting South-West England on the (strontium isotope) map: A possible origin for highly radiogenic 87Sr/86Sr values from southern Britain

Reconstructions of ancient mobility based on strontium isotopes are only ever as reliable as estimates for baseline values of bioavailable strontium in the study area. Current biosphere mapping for Britain suggests that there are no sizeable areas hosting 87Sr/86Sr values above 0.714 south of Cumbria. As a result, archaeological humans or animals with such (for Britain) ‘highly radiogenic’ strontium isotope values are commonly interpreted as having moved either from Scotland or abroad. This paper presents the first dedicated strontium isotope map for South-West England based on 98 modern biosphere samples (including 68 new measurements). Numerous samples from the Cornubian granite (Dartmoor) have 87Sr/86Sr values above 0.714 (maximum 0.7287) and, based on their distribution, it is suggested that the previously elusive ‘highly radiogenic’ values are characteristic for areas where the soil has with high rubidium concentrations. These occur at lower elevations which are better suited for agriculture and permanent human settlement than the high moors. Previous interpretations of archaeological samples from southern Britain may need to be revised considering these new results, but they also highlight the continued need for biosphere sampling and the usefulness of geochemical maps as a routine part of strontium isotope investigations in archaeology.

On the origin of Shuram carbon isotope excursion in South China and its implication for Ediacaran atmospheric oxygen levels

The Ediacaran Shuram excursion marks one of the largest carbon isotope excursions in Earth’s history, but its origin remains enigmatic. In this study, we examine a carbonate section from Yangtze Gorges Area, South China that archives the Ediacaran Shuram excursion (i.e., “DOUNCE” event in South China), and report its carbon (δ13C), oxygen (δ18O), calcium (δ44/40Ca) together with published radiogenic strontium (87Sr/86Sr) isotope values. We find that the negative δ13C excursion coincides with decreases of δ18O and δ44/40Ca values, along with a positive shift in 87Sr/86Sr ratios. Two different but internally-coherent mechanisms can attribute to our observations—extensive diagenetic alteration under different fluid-buffered systems and coastal processes, and we speculate that both of them may have played important roles in shaping the observed isotope patterns. Using a coupled C-O-Sr-Ca model, we find that these two processes both require an isotopically (13C, 18O, 44Ca) depleted exogenous fluid source (meteoric water or groundwater), potentially generated by oxidation of lithospheric organic carbon. Our hypothesis is consistent with the unique hydrogeological condition in Yangtze Gorge area during the middle Ediacaran. Further, we use an organic matter and pyrite oxidation model to provide a new conservative constraint for middle Ediacaran oxygen partial pressure (pO2). A 10–20% present atmospheric level (PAL) of oxygen concentration is estimated if the Shuram excursion can be more confidently linked to meteoric water or groundwater impacts.

Childhood and Adulthood Residency Prediction Using Strontium (87Sr/86Sr) and Oxygen (δ18O) Isotopes for Unidentified Deceased Migrants Recovered in Southern Texas

Strontium and oxygen isotope values are used in conjunction with a maximum likelihood assignment model to predict the childhood and adulthood geographic residences of 20 deceased migrants recovered along the México-U.S. border in south Texas. The objectives of this research are to determine (1) if the childhood and adulthood residency assignments predict the same geographic region, (2) if using the predicted residential history/nationality as a filter on the National Missing and Unidentified Persons System (NamUs) reduces the number of potential matching missing person reports, and (3) if we should target teeth or bone as the optimal hard tissue to sample. We found that 12 of the 20 cases (60%) predict similar regions of residency using isotopes derived from bone bioapatite (adulthood residency) and tooth bioapatite (childhood residency). When predicted residential history/nationality data were used as a filter in NamUs, there was a significant reduction in the mean number of case searches (mean = 1568.5 ± 505.3 [1 SD] vs. 107.9 ± 142.6 [1 SD]; t = 12.441, df = 22, p < 0.001, unequal variances assumed). These results demonstrate the utility of isotope data for narrowing down the region of origin and in turn the number of missing persons records to review. Finally, we recommend that death investigators at minimum collect dental samples (premolars or molars) for future unidentified migrant cases to aid in identification efforts utilizing isotope analytical methods. Bone bioapatite samples can provide more recent residential history information but should be used in conjunction with tooth enamel data.

Comparison of human and faunal enamel isotopes reveals diverse paleodiet and exchange patterns at the highland Maya Site of Kaminaljuyu, Guatemala

This study provides an isotopic examination of both human and animal paleodiets and mobility patterns at a highland Maya community. Kaminaljuyu, Guatemala, was a large Prehispanic center located in a distinctly cooler, drier setting compared with the majority of Maya sites in the surrounding lowlands. Previous archaeological research at Kaminaljuyu revealed it played an important political and economic role in the Maya region, assisting in the obsidian trade network and maintaining ties with communities as far away as Teotihuacan in central Mexico. By examining the strontium (87Sr/86Sr), carbon (δ13C), and oxygen (δ18O) isotope values from dental enamel of humans and terrestrial mammals at the site, this study provides direct evidence of long-distance animal trade, explores the nature and timing of such activities, and compares highland dietary patterns with faunal studies in the lowlands. Our results indicate that isotopically non-local humans and animals are most frequently found in special and ceremonial contexts, indicating that long-distance movements of people and products were motivated for politically or ritually significant events. Although dietary patterns showed cross-species variation, diets within species were similar between highland and lowland settings.

Application of U-Pb dating technique in the study of hydrothermal activities of dolomite reservoir: A case study on 3<sup>rd</sup> member of Yingshan Formation in Gucheng area, Tarim Basin, NW China

古城地区是塔东探区的重点勘探区块，下奥陶统鹰三段是塔东探区首要的勘探层系。探寻多期热液作用改造后的优质白云岩储层是扩大研究区勘探成果的关键。本文在储层岩石学特征判识的基础上，应用U-Pb同位素定年技术，结合碳氧锶镁同位素和稀土元素分析测试，分析了热液性质，明确了热液作用发生的确切时期及期次，探讨了热液作用对白云岩储层的影响。研究结果表明，古城地区鹰三段白云岩储层发育准同生-浅埋藏海水成因的粉晶-中晶白云岩及热液作用产物。热液作用可划分为二期：第一期为中-晚奥陶世贫镁热液，表现为鞍状白云石充填缝洞及重结晶次生加大的粗晶白云石，U-Pb测定年龄为464±12Ma到473.9±9.1Ma，氧同位素值比早奥陶世正常海相白云石明显偏负，锶同位素比值明显高于早奥陶世海水值，稀土元素Eu正异常，锶、铁、镁元素含量低；第二期为晚奥陶世-早志留世钙质热液，表现为方解石充填缝洞及对先存白云石的溶蚀，U-Pb测定年龄为448±15Ma到457.4±6.6Ma，氧锶同位素组成严重偏离同时期正常海相白云石范围，轻稀土元素明显富集，Eu正异常，锶、钙元素含量高，锰元素含量低。第二期热液作用是白云岩储层溶蚀的关键，同期NNE向断裂带作为其输导系统，是优质储层发育的有利部位，为有利区带预测提供依据。;The dolomite in 3^rd member of Yingshan Formation in Gucheng area is a significant exploration field in the east of Tarim Basin. High-quality dolomite reservoir reworked by hydrothermal activities is the key to expand exploration. Based on petrographic characteristics, this paper analyzed hydrothermal properties, clarified the precise dating and stages of hydrothermal process, and discussed hydrothermal effects on dolomite reservoir using U-Pb dating technique, combined with analysis of carbon and oxygen, strontium, magnesium isotopes and rare earth elements. The study shows that micrite-medium grained dolomites taken place in paracontemporaneous-shallow buried phase and hydrothermal products in research area. There are two stages of hydrothermal processes. The first stage hydrothermal process is very low in magnesium content in the Middle-Late Ordovician, at the result of saddle dolomite filling in fractures/vugs and coarse dolomite formed by recrystallization aged 464±12Ma~473.9±9.1Ma by U-Pb dating with oxygen isotope negative compared with normal marine dolomite, strontium isotope values higher than Early Ordovican sea values and positive Eu anomalies. The contents of strontium, ferrum and magnesium are relatively low. The second stage hydrothermal process is high in calcium content in the Late Ordovician-Early Silurian, at the result of calcite filling in fractures/vugs and dissolution of existing dolomites, aged 448±15Ma~457.4±6.6Ma by U-Pb dating with significantly negative oxygen isotope and enriched LREE and positive Eu anomalies. The strontium content is high while manganese content is low. Migration pathway of the second stage hydrothermal process as a key of dolomite reservoir dissolution is NNE fracture zones developing high-quality reservoir, which provides a basis for the prediction of favorable zones.

A Messinian Gypsum Deposit in the Ionian Forearc Basin (Benestare, Calabria, Southern Italy): Origin and Paleoenvironmental Indications

This study reports the first accurate record of the Messinian Resedimented Gypsum in the forearc and back-arc basins connected to the Calabrian-Peloritan orogen. A multidisciplinary approach has been used to investigate a gypsum deposit located in the Benestare’s area (Calabria, Southern Italy). Such deposit is made of bedded gypsrudites displaying clastic selenite with chaotical textures. On the top, the gypsrudites are interspersed with gypsum lenses belonging to the branching-like facies. Despite these two facies seem different macroscopically, they show petrographic features, fluid inclusions, organic matter and Strontium isotopic values very similar to each other. On the other hand, both facies show fractured and folded crystals. Crystals are only locally corroded and preserve primary structure relict as well as allochthonous (organic debris) and autochthonous putative microbial remains. All crystals are rich in fluid inclusions but these are visibly affected by stretching and leaking (re-equilibration processes) suggesting a moderate plastic deformation during re-sedimentation and subsequent burial. Minimal transport of the deposit is testified by subangular shapes of the gypsum crystals. The gypsrudite and branching-like facies reveal an 87Sr/86Sr average value of 0.709045 and 0.709082, respectively. These values suggest a strong connection with the global Ocean and reduced freshwater input. The Benestare’s deposit originated from the partial to complete dismantling of selenite crystals related to the first stage (5.97–5.60 Ma) of the Messinian Salinity Crisis through gravitational collapse due to local controlling factors.

Problems with Strontium Isotopic Proveniencing in Denmark?

A recent study by Thomsen and Andreasen (2019) has induced a negative reaction to the usefulness of strontium isotope proveniencing. Although there are higher strontium isotope values in the landscape of Denmark, Thomsen and Andreasen are not correct about the impact of this finding on studies of prehistoric mobility. Several case studies identify such “hotspots” in the landscape and help evaluate their consequences for identifying non-local individuals. In sum, (1) there are small areas of higher strontium isotope values in Denmark, (2) surface water is not a reliable proxy for baseline information on local strontium isotope sources, and (3) strontium isotope proveniencing remains a very useful method for identifying non-local individuals.

Fluid Histories of Middle Ordovician fault–fracture hydrothermal dolomite oil fields in the southern Michigan Basin, U.S.A.

ABSTRACTDolomitized fault–fracture structures in the Trenton and Black River formations (TBR) are the type example for “hydrothermal” petroleum reservoirs world-wide. However, fluid histories of these structures are only partially understood. Trenton and Black River reservoirs in the southern Michigan Basin are composed of fault-associated, vertical dolomite bodies that are highly fractured and brecciated. Open spaces are partially to completely filled by saddle dolomite and less frequently by calcite cement. Cathodoluminescence microstratigraphies of void-filling carbonate cements are not correlatable between oil fields. Fluid inclusion homogenization temperatures (Th) measured in carbonate cements indicate two fluid endmembers: a warm fluid (∼ 80° to 180° C) and a hot fluid (180° to ∼ 260° C). Increasing Th proximal to the underlying Proterozoic Mid-Michigan Rift (MMR) suggest that the hot fluids emanated from the rift area. Included fluids are saline (16.1–49.4 wt. % NaCl equivalent), and salinity likely is sourced from overlying Silurian Salina Group evaporites. First melting temperatures (Tfm), interpreted as eutectic temperatures (Te), of fluids range from –112° C to –50° C, indicating a complex Na–Ca–KCl brine; the expected composition of dissolved Salina salts. Lower Te proximal to the MMR suggest the rift as a source of additional complexing ions. C and O isotope values for carbonate cements are depleted with respect to δ18O (–6.59 to –12.46‰ VPDB) relative to Ordovician seawaters, and somewhat depleted with respect to δ13C (–1.22 to +1.18‰ VPDB). Equilibrium calculations from δ18O and Th values indicate that cement precipitating waters were highly evolved (+1.3 to +14.4‰ δ18O‰ VSMOW) compared to Ordovician and Silurian seawaters (–5.5‰ δ18O‰ VSMOW). Strontium isotope values indicate two fluid sources: Proterozoic basement and Late Silurian evaporites. Values of 87Sr/86Sr for cements in the Freedom, Napoleon, Reading, and Scipio fields (0.7086–0.7088) are influenced by warm water sourced from Silurian strata, and values for cements in the Albion, Branch County, and Northville fields (0.7091–0.7110) record continental basement signatures. Cement precipitating fluids in TBR oil fields likely have similar sources and timing. However, water–rock interactions along fault pathways modified source waters, giving each oil field a unique petrographic and geochemical signature. Fluid movement in TBR oil fields likely were initiated by reactivation of basement faulting during Silurian–Devonian tectonism.

Strontium isotope evidence for Neanderthal and modern human mobility at the upper and middle palaeolithic site of Fumane Cave (Italy).

To investigate the mobility patterns of Neanderthals and modern humans in Europe during the Middle-to-Upper Palaeolithic transition period, we applied strontium isotope analysis to Neanderthal (n = 3) and modern human (n = 2) teeth recovered from the site of Fumane Cave in the Monti Lessini region of Northern Italy. We also measured a large number of environmental samples from the region, to establish a strontium ‘baseline’, and also micromammals (vole teeth) from the levels associated with the hominin teeth. We found that the modern humans and Neanderthals had similar strontium isotope values, and these values match the local baseline values we obtained for the site and the surrounding region. We conclude that both groups were utilizing the local mountainous region where Fumane Cave is situated, and likely the nearby Lessini highlands and Adige plains, and therefore the strontium evidence does not show differening mobility patterns between Neanderthals and modern humans at the Fumane site.

Modern isotopic signatures of Plata River sediments and changes in sediment supply to the western subtropical South Atlantic during the last 30 kyr

Sediments transported in rivers reflect the geology of the catchment area and its radiogenic isotopic composition. These isotopic signatures are not significantly altered by weathering, transport or deposition and hence can document variations in sediment supply. Here we present strontium (Sr), neodymium (Nd) and lead (Pb) isotope values from suspended and riverbed sediments of the Plata River drainage basin, the second largest on the South American continent, and from two marine sediment cores collected off the mouth of the Plata River in the western subtropical South Atlantic. Our modern riverine data suggest that the basin has three main sediment source areas, namely the upper Paraná River, the Uruguay River and the Andean draining rivers. Sediments from the Andean draining rivers (Salado and Bermejo Rivers) have the most radiogenic Pb (i.e. >18.5 for 206Pb/204Pb) and Sr (average of 0.726 ± 0.031; 2SD) isotopic signatures, and least radiogenic εNd values (average of −10.5 ± 3.1; 2SD). The upper Paraná and Uruguay Rivers have less radiogenic Pb (i.e. <18.5 for 206Pb/204Pb) and Sr (average of 0.715 ± 0.003; 2SD) isotopic signatures. While the upper Paraná River has average εNd values of −7.8 ± 1.1 (2SD), the Uruguay River has average εNd values of −5.9 ± 0.2 (2SD). The modern isotopic signature at the mouth of the Plata River is largely dominated by the Andean draining rivers. To reconstruct changes in sediment supply to the western subtropical South Atlantic, we used this new riverine dataset together with literature values from the Argentine continental margin to interpret the data from two marine sediment cores. The downcore records cover the last ∼30 kyr and show two short-lived excursions (i.e. Heinrich Stadial 1 and the Younger Dryas) and two long-term trends (i.e. late Pleistocene (i.e. ∼29 to 11 cal ka BP for Sr and ∼29 to 25 cal ka BP for Nd), and early and mid-Holocene). We suggest that the short-lived excursions result from increased precipitation in the headlands of the Andean draining rivers during Heinrich Stadial 1 and the Younger Dryas. The late Pleistocene long-term change showed an increase in the contribution of material from the Plata River drainage basin in relation to material from the Argentine continental margin most probably due to low sea-level. The early and mid-Holocene long-term trend showed the opposite change in sediment input and was related to decreased precipitation over most of the Plata River drainage basin.

A bioavailable baseline strontium isotope map of southwestern Turkey for mobility studies

We present here a map of bioavailable strontium for Southwestern Turkey derived from measurements of modern plants and mollusk (land snail) shells from various geological areas. Samples were collected from 87 locations and strontium isotope measurements were made on 283 plant and mollusk samples. The plants consisted of deep-rooted, medium-rooted and shallow-rooted species each sampling strontium from different water sources. The data was interpolated to produce a predictive strontium isotope map (‘Sr-isoscape’) of the region. Despite the complex underlying geology of this region the bioavailable Sr values broadly grouped into two separate areas, related to the age of the underlying bedrock. These results provide a baseline for interpretation of strontium isotope values of archaeological samples to help understand past animal and human mobility, and can also be used by researchers in a range of other disciplines that incorporate strontium analysis for mobility, including animal ecology and forensics.

Stable oxygen and radiogenic strontium variability in the Osmore Drainage, Peru: Implications for intra-regional Andean paleomobility studies

The Osmore Drainage of southern Peru has a long and rich history of human occupation. While the utility of stable oxygen and radiogenic strontium isotope values in identifying paleomobility between this region and population centers in the Bolivian altiplano has been well established, many questions about intra-regional mobility remain. To better understand how these methods can be used to detect localized residential mobility, we present new δ18Omw(VSMOW) and 87Sr/86Sr values from water, soil, plant, and faunal samples. Samples were collected primarily from traditionally farmed agricultural fields in the upper, middle, and lower Osmore Drainage. Results are indiscernible between the upper and middle drainage, while marine contribution to the lower drainage produces distinct values. We discuss the methodological limitations and implications of our results for the use of stable oxygen and radiogenic strontium isotope analyses for intra-regional paleomobility studies in the Osmore Drainage.

Geologic variability of conodont strontium isotopic composition quantified by laser ablation multiple collection inductively coupled plasma mass spectrometry

Conodont microfossils record seawater strontium isotope values (87Sr/86Sr), permitting chemostratigraphic correlation for tectonic and climatic reconstructions of the Paleozoic and early Mesozoic (541–201 Ma). Laser ablation multiple collection inductively coupled plasma mass spectrometry (LA MC-ICP-MS) can provide rapid, high spatial resolution 87Sr/86Sr analysis of conodont bioapatite but has not been validated by comparison with solution analysis. Validation of LA MC-ICP-MS should be completed in order to use the conodont 87Sr/86Sr values for age-correlations and environmental interpretations. Here, for the first time, we compare solution and LA MC-ICP-MS 87Sr/86Sr analyses of Carboniferous-age conodonts. Furthermore, we use quadrupole LA ICP-MS to determine concentrations of trace elements potentially responsible for isobaric interferences. Using increased mass resolving power (m/∆m = ~7500) and analyzing conodont tissue with low 85Rb/88Sr (< 0.001), we find laser ablation copacetic with solution 87Sr/86Sr values. The two-standard-deviation of these LA 87Sr/86Sr ratios (average 2SD = 0.00105) are within the two-standard-error uncertainty of solution measurements (average 2SE = 0.00001) on conodonts from the same stratigraphic level. The LA measurements are at a higher spatial resolution and on average 0.00015 higher than solution measurements. Uncertainty of the mean calculations, made on duplicate LA MC-ICP-MS analyses of individual conodonts from the same stratigraphic level, exhibit 87Sr/86Sr variability beyond the precision of reference materials (2SE = 0.00001). This finding suggests that solution 87Sr/86Sr values determined by dissolving multiple conodonts are homogenizing the conodont 87Sr/86Sr signal. As such, the precision of these solution measurements does not capture the geologic variability of conodont 87Sr/86Sr within a stratigraphic level, which may originate from differential diagenetic alteration. Conodont 87Sr/86Sr measurements that do not account for this variability are at risk of false calibrations with the paleo-seawater 87Sr/86Sr curve, which has implications for the timing of geologic events and reconstructions of paleo-environmental changes.

Interdisciplinary Analysis of the Lehi Horse: Implications for Early Historic Horse Cultures of the North American West

Although recognized as one of the most significant cultural transformations in North America, the reintroduction of the horse to the continent after AD 1492 has been rarely addressed by archaeological science. A key contributing factor behind this limited study is the apparent absence of equine skeletal remains from early historic archaeological contexts. Here, we present a multidisciplinary analysis of a horse skeleton recovered in Lehi, Utah, originally attributed to the Pleistocene. Reanalysis of stratigraphic context and radiocarbon dating indicates a historic age for this horse (cal AD 1681–1939), linking it with Ute or other Indigenous groups, whereas osteological features demonstrate its use for mounted horseback riding—perhaps with a nonframe saddle. DNA analysis indicates that the animal was a female domestic horse, which was likely cared for as part of a breeding herd despite outliving its usefulness in transport. Finally, sequentially sampled stable carbon, oxygen, and strontium isotope values from tooth enamel (δ13C, δ18O, and 87Sr/86Sr) suggest that the horse was raised locally. These results show the utility of archaeological science as applied to horse remains in understanding Indigenous horse pastoralism, whereas consideration of the broader archaeological record suggests a pattern of misidentification of horse bones from early historic contexts.