Strontium Isotope Research Articles

Geochemistry and Sr, S, and O stable isotopes of Miocene Abu Dhabi evaporites, United Arab Emirates

This study investigates for the first time the subsurface Miocene evaporite facies (Gachsaran Formation) in Abu Dhabi, United Arab Emirates. Forty-five evaporite rock samples were selected for petrographic, mineralogical, and geochemical investigations and stable isotope analyses to decipher their origin and constrain their age. Secondary gypsum with anhydrite relics dominates the investigated evaporitic rocks, with minor amounts of clays, dolomicrite, Fe/Ti oxides, and celestite. These samples are characterized by their excellent purity and low variability in geochemical composition. The distribution of trace element concentrations is significantly influenced by continental detrital intake. The main focus of the study is to determine the strontium, sulfur, and oxygen stable isotope compositions. The measured 87Sr/86Sr values of 0.708411–0.708739 are consistent with Miocene marine sulfates and indicate ∼21.12–15.91 Ma (Late Aquitanian-Burdigalian). The δ34S and δ18O values are 17.10‰–21.59‰ and 11.89‰–19.16‰, respectively. These values are comparable to those of Tertiary marine evaporites. The relatively low values of δ34S suggest that non-marine water possesses little influence on S distribution. The geochemical composition and Sr, S, and O isotope distributions of the Abu Dhabi gypsum facies from the Gachsaran Formation reveals that their source brines were marine (coastal saline/sabkha) with subordinate continental input.

Application of the δ44/40Ca-δ88/86Sr multi-proxy to Namibian Marinoan cap carbonates

Several studies have exploited the stable calcium (Ca) and strontium (Sr) isotope compositions of marine carbonate rocks to investigate ancient carbon cycle dynamics, seawater geochemistry, and controls on carbonate production and preservation. However, the two proxies have rarely been applied together. Based on knowledge achieved to date, the δ44/40Ca-δ88/86Sr multi-proxy can distinguish signatures imparted by mass-dependent fractionation and reservoir mixing, including early diagenesis and shifts in the isotopic composition of seawater. In detail, the δ44/40Ca-δ88/86Sr multi-proxy represents a five-isotope system because the determination of δ88/86Sr values requires analysis of fractionation-corrected 87Sr/86Sr ratios, which provide additional constraints on mixing. Here, we apply the novel δ44/40Ca-δ88/86Sr multi-proxy to two Marinoan (ca. 635 Ma) “cap carbonate” sequences from Namibia. Cap carbonates were widely deposited after the Neoproterozoic Marinoan Snowball Earth Event, but controversy surrounds their origin. We find that the rocks archive primary environmental signals deriving from a combination of seawater-glacial meltwater mixing and kinetic isotope effects. In an outer platform section, dolostone δ44/40Ca and δ88/86Sr values define a line predicted for kinetic mass-dependent isotope fractionation. This dolostone mostly precipitated from meltwater. Moreover, stratigraphically higher samples exhibiting the fastest precipitation rates display elevated 87Sr/86Sr ratios, consistent with long-held expectations that a rapid deglacial weathering pulse forced cap carbonate formation. An inner-platform dolostone shows greater effects from water-mass mixing but still reveals that precipitation rates increased up-section. Overlying limestones show greater Ca and Sr contributions from seawater. Amplification of local coastal processes during global ice sheet collapse offers a simple but sufficient proposition to explain the Ca isotope heterogeneity of cap carbonates. Detection of kinetic isotope effects provides evidence for predominantly rock-buffered diagenesis and further offers a basis for developing the δ44/40Ca-δ88/86Sr multi-proxy as an indicator of saturation state and pCO2.

Carbonate diagenesis: A celebration of the work of John Anthony Dawson (Tony) Dickson

Carbonate diagenesis: A celebration of the work of John Anthony Dawson (Tony) Dickson

Animal husbandry, isotopes, and land use at the Late Bronze Age Hittite city of Şapinuva (Šapinuwa), Turkey: insights from strontium isotopes

Animal husbandry, isotopes, and land use at the Late Bronze Age Hittite city of Şapinuva (Šapinuwa), Turkey: insights from strontium isotopes

Strontium Isotope Characteristics (δ88/86Sr, 87Sr/86Sr) of Arima‐Type Brines Originated From Slab‐Fluids

AbstractIn the southwest Japan forearc, slab‐fluids produced from subducted materials migrate to crustal levels and appear as deep‐seated brine. We have analyzed for the first‐time stable strontium isotopes in non‐volcanic spring water with high salinity, referred to as Arima‐type saline water that likely originate from slab‐fluid that upwelled along major faults. The stable strontium isotope compositions of the saline water are isotopically light (δ88/86Sr = 0.122–0.157‰) and different from those of local bedrock and near‐surface water. The light strontium‐enriched and radiogenic signature of the saline water reflects the primary characteristic of slab‐fluids without an isotopic overprint in the crust. The Arima‐type brines show signatures of slab‐fluids at forearc depth, which is different from the slab‐fluids at subarc depth estimated from arc lavas. The characteristic features of the Arima‐type brines are explained by a larger contribution of subducted sediments and strontium isotope fractionation during fluids generation at shallower depth.

A strontium isoscape of northern Australia

Abstract. Strontium isotopes (87Sr/86Sr) are useful to trace processes in the Earth sciences as well as in forensic, archaeological, palaeontological, and ecological sciences. As very few large-scale Sr isoscapes exist in Australia, we have identified an opportunity to determine 87Sr/86Sr ratios on archived fluvial sediment samples from the low-density National Geochemical Survey of Australia. The present study targeted the northern parts of Western Australia, the Northern Territory, and Queensland, north of 21.5∘ S. The samples were taken mostly from a depth of ∼60–80 cm in floodplain deposits at or near the outlet of large catchments (drainage basins). A coarse (<2 mm) grain-size fraction was air-dried, sieved, milled, and digested (hydrofluoric acid + nitric acid followed by aqua regia) to release total Sr. The Sr was then separated by chromatography, and the 87Sr/86Sr ratio was determined by multicollector inductively coupled plasma mass spectrometry. The results demonstrate a wide range of Sr isotopic values (0.7048 to 1.0330) over the survey area, reflecting a large diversity of source rock lithologies, geological processes, and bedrock ages. The spatial distribution of 87Sr/86Sr shows coherent (multi-point anomalies and smooth gradients), large-scale (>100 km) patterns that appear to be broadly consistent with surface geology, regolith/soil type, and/or nearby outcropping bedrock. For instance, the extensive black clay soils of the Barkly Tableland define a >500 km long northwest–southeast-trending unradiogenic anomaly (87Sr/86Sr <0.7182). Where sedimentary carbonate or mafic/ultramafic igneous rocks dominate, low to moderate 87Sr/86Sr values are generally recorded (medians of 0.7387 and 0.7422, respectively). Conversely, In proximity to the outcropping Proterozoic metamorphic basement of the Tennant, McArthur, Murphy, and Mount Isa geological regions, radiogenic 87Sr/86Sr values (>0.7655) are observed. A potential correlation between mineralization and elevated 87Sr/86Sr values in these regions needs to be investigated in greater detail. Our results to date indicate that incorporating soil/regolith Sr isotopes in regional, exploratory geoscience investigations can help identify basement rock types under (shallow) cover, constrain surface processes (e.g. weathering and dispersion), and, potentially, recognize components of mineral systems. Furthermore, the resulting Sr isoscape and future models derived therefrom can also be utilized in forensic, archaeological, palaeontological, and ecological studies that aim to investigate, for example, past and modern animal (including humans) dietary habits and migrations. The new spatial Sr isotope dataset for the northern Australia region is publicly available (de Caritat et al., 2022a; https://doi.org/10.26186/147473).

A bioavailable strontium isoscape of Angola with implications for the archaeology of the transatlantic slave trade

The region of present-day Angola was one of the main areas from which millions of enslaved Africans were abducted and forced to migrate to the Americas during the transatlantic slave trade. Strontium isotope (87Sr/86Sr) analysis is a useful tool in reconstructing large-scale human movements across geologically distinct landscapes in archaeological and forensic contexts. However, the absence of environmental 87Sr/86Sr reference data from Angola hinders the use of 87Sr/86Sr analysis in provenance studies related to Angola, especially in identifying the geographic origin of enslaved people in the African Diaspora. Here, we measured 101 plant samples from most, yet not all, major geological units to draft the first bioavailable 87Sr/86Sr map (isoscape) for Angola using a machine learning framework. Our results suggest that the 87Sr/86Sr ratios in Angola span a large range from 0.70679 to 0.76815 between the different geological units. Specifically, the high average 87Sr/86Sr ratios of 0.74097 (±0.00938, 1 SD) found in the Angola Block of central Angola, are distinctly more radiogenic than any previously published bioavailable 87Sr/86Sr ratios for western Central and West Africa. However, these match the 87Sr/86Sr ratios previously published for human enamel samples from four historic slavery contexts in the Americas. We demonstrate that our strontium isoscape of Angola greatly improves the ability to assess the possible origins of enslaved African individuals discovered outside of Africa and encourage the future use of emerging African isoscapes in the study of life histories within the slave trade.

Metals and pigments at Amara West: Cross-craft perspectives on practices and provisioning in New Kingdom Nubia

This paper presents the results of elemental and lead isotopic analysis of copper alloys, copper-based pigments and an extremely rare tin-based alloy from the town of Amara West (Sudan), the centre for pharaonic control of occupied Upper Nubia between 1300 and 1070 BCE. It is the first assemblage of its kind to be analysed for Upper Nubia during this period. This research examines the selection and consumption of alloys in a colonial context, in light of earlier and contemporaneous practices and patterns in both Egypt and Nubia, to assess broader systems of resource management and metal production. Drawing on the complementary information obtained from pigment analysis, novel insights into interactions between different high-temperature crafts are obtained, particularly in terms of shared provisioning systems. From this unique perspective, pigment analysis is used for the first time to illuminate copper sources not reflected in metal assemblages, while scrap copper alloys are identified as a key colourant for Egyptian blue manufacture. The integrated application of strontium isotope analysis further highlights the potential for identifying links between glass, faience and Egyptian blue production systems within Egypt and for distinguishing these from other manufacturing regions such as Mesopotamia. The analysis of a tin artefact further expands our understanding of potential tin sources available during the New Kingdom and their role in shaping copper alloy compositions. Overall, this holistic approach to copper alloys and their application in other high-temperature industries ties together different strands of research, shaping a new understanding of New Kingdom technological practices, supply networks and material stocks circulating throughout the Nile Valley.

Provenance and transport mechanism of gravity core sediments in the deep-water area of the Qiongdongnan Basin, northern South China Sea

Reconstructing the role of provenance and transport mechanism of sediments deposited in deep-water environments is often complex because of myriad of factors such as variability in sediment sources, tectonics, bottom morphology, climatic changes and sea level fluctuations as well as current regime. The South China Sea (SCS) is situated at the tectonic intersection of the Pacific, Eurasian, and Indo-Australian plates, and provides an excellent natural laboratory for understanding source-to-sink transport processes of fluvial sediments. The Qiongdongnan Basin (QDNB) is located in the northern part of the SCS, and the deep-water area (>300 m) of the QDNB has a good hydrocarbon source and hydrocarbon accumulation conditions with a tremendous thickness since the late Miocene-Quaternary. However, the complex sources and transport mechanisms of sediments in the QDNB are undefined. In previous study QDNB may have a major provenance or a mixture of sources. In this paper, the sediments of two cores from the deep-water area of QDNB have been analyzed using several sedimentological and geochemical approaches, including measurements of grain size distribution(433 samples), the occurrence of minerals, and trace element geochemistry(37 samples)as well as strontium and neodymium isotopes(20 samples).The granularity analysis results first show that the 19S37 core can be divided into three stages while the 19S40 core is divided into two stages by clear vertical variations in grain size characteristics. Chlorite (62.0%) and Muscovite (33.6%) appear to be the predominant minerals in the 19S37 core, while the mineral assemblage of sediments from 19S40 mainly consists of kaolinite (37.4%), muscovite (29.2%) and chlorite (27.1%). The primitive mantle standardization curves and chondrite standardized distribution patterns of 19S37 and 19S40 are consistent and display enrichments in Th, U, Pb, and Nd and depletions in Ba, Nb, Sr, and Eu. In addition, the content of Sr fluctuates greatly with depth, which should reflect the influences of sea level changes and the relative proportion of various provenance components. The 143Nd/144Nd ratios and εNd values of the sediments from 19S37 are higher than those of the sediments from 19S40, and all the εNd values show narrow variations and range from −10.085 to −11.080. We conclude that the sediments of the deep-water area in the upper Pleistocene-Holocene were mainly from the sources of the Red River, Taiwan, Pearl River, Hainan Island, and Vietnam. The transport mechanism of the sediments from Hainan Island can be explained by the short distance between the source region and the sedimentary site, while the large amounts of terrigenous sediment inputs derived from the Red River and advantageous morphology make the Red River the largest sediment source to cores 19S37 and 19S40. The transport distance and amount of Deep Water Current could be even more powerful to make Taiwan be the second largest source of modern sediments in QDNB.

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.

Stabbed to death: an osteobiography example of violence among Longobards (Povegliano Veronese, Italy, 6th-8th c CE)

Herewe report the reconstruction of the osteobiography of an adult male buried in the Longobard cemetery of Povegliano Veronese (Northern Italy, late 6th – early 8th century CE), who shows signs of interpersonal violence. The palaeopathological investigation reveals sharp force traumas on the body of the fourth lumbar vertebra and on two right ribs. The absence of signs of healing or bone remodelling indicates that the defects were perimortem. The injuries probably affected vital organs, leading to death. Further macroscopic observations of the skeleton suggest horseback-riding activity. Strontium isotope data from tooth enamel indicate a non-local origin of the individual. X-ray and CT scan acquisition and Scanning Electron Microscopy analyses were performed to investigate the bone defects. His osteobiography was interpreted and contextualised in the complex socio-political scenario of post-classical Italy. The results document that he spent his childhood outside the Povegliano Veronese area, that during his life he was likely a horseback rider active in battle, but that his violent death did not happen during warfare/battle. This multi-layered approach, supported by archaeological information, osteological investigation, biomolecular analysis, and virtual imagery, allowed for the extensive reconstruction of an individual's life history.

Abrupt Changes in Atmospheric Circulation During the Medieval Climate Anomaly and Little Ice Age Recorded by Sr‐Nd Isotopes in the Siple Dome Ice Core, Antarctica

AbstractThe Southern Hemisphere westerly winds (SWW) play a critical role in global climate, yet their behavior on decadal to centennial timescales, and the mechanisms driving these changes during the preindustrial era, remain poorly understood. We present a decadally resolved record of dust compositions using strontium and neodymium isotope ratios in mineral dust from the Siple Dome ice core, Antarctica, to explore the potential that abrupt changes in SWW behavior occurred over the past millennium. The record spans portions of the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) intervals as defined in the Northern Hemisphere. We find evidence of an abrupt strengthening of atmospheric circulation during the MCA at ∼1125 CE (825 BP) that persisted for about 60 yr, indicating increased influence of Patagonia‐sourced dust. This occurs during an extended positive phase of Southern Annular Mode (SAM+)‐like conditions, characterized by high SWW velocities and a southerly shift of the main wind belt toward ∼60°S, suggesting that rapid changes in SWW strength could occur under the present SAM+ pattern. A second 20 yr long shift in dust compositions during the LIA at ∼1748 CE (200 BP) is coincident with higher dust delivery to Siple Dome, and may indicate increased dust emissions related to glacier activity in Patagonia. The new Siple Dome ice core data set demonstrates that Sr‐Nd isotopes can be used to trace shifts in atmospheric circulation on decadal timescales.

Exploring Intersectional Identities and Geographic Origins in Ancient Nubia at Tombos, Sudan

As part of an intersectional investigation of changes in identity and lifeways during sociopolitical changes in the ancient Nile Valley, strontium isotope analysis has provided a useful entry for understanding local practices. At the site of Tombos, human residential mobility was spurred through Egyptian imperial actions in Nubia during the New Kingdom period (~1450–1050 B.C.). During this period, immigrants and locals interacted and influenced cultural symbols displayed in burials with migration ending with Egyptian occupation. Through the examination of multiple overlapping identities and experiences, patterns emerge. Isotopically identified locals are exclusive in tumulus graves and flexed body position (all skeletally sexed as female), consistent with the surrounding region.
 However, locals also used materials and practices associated with the colonizers, including pyramid, chapel, and shaft tomb types; extended body position; coffins; and artifacts. These variations provide evidence of simultaneous experiences of multiple social statuses at Tombos. The findings provide fruitful avenues to explore motivations for varying identity expression related to such ideas as family traditions, religious beliefs, gender dynamics, deliberate signaling, and the concept of foreignness. Theoretical and intersectional approaches to isotope analyses also necessitate a reassessment of methodological, analytical, and ethical issues associated with research.

Ultra-deep carbonate basement reservoirs formed by polyphase fracture-related karstification in the Offshore Bohai Bay Basin, China

The Palaeozoic carbonate basement of the Offshore Bohai Bay Basin (OBBB) presents considerable potential for hydrocarbon exploration. However, the multistage tectonism and complex superimposed palaeo-karstification in the area are unclear, which leads to a lack of understanding on the formation mechanism and distribution of the deep carbonate basement reservoirs. In this study, the occurrence of a fracture-vug network and its fillings in carbonate reservoirs were investigated based on borehole cores, thin sections, and image logs from the southwestern slope of the OBBB's Bozhong Sag. Then the diagenetic fluid properties of the carbonate matrix and fillings were analysed via the data of carbon, oxygen, and strontium isotopes, and major, rare elements from coring intervals. The results revealed that fracture-related karst reservoirs have lithologic selectivity inclined toward dolomite strata. The intersecting relationships, widths, and strikes of the fractures and the regional tectonic background indicate three structural fracture families: NW-, NNE-, and NNW- trending, related to the Indosinian, middle Yanshanian, and late Yanshanian orogeny, respectively. The Indosinian NW- and end-Mesozoic NNE-trending fractures produced by compressional tectonic stress mainly contributed to the formation of the basement reservoirs. The geochemistry of the calcite veins filling these fractures suggests two main types of diagenetic fluids. The fluid of autogenic recharge related to the earlier fills is karstification diffuse flow dominated by internal runoff from rainfall in the highland setting of the Indosinian thrusting orogenic belt. The other fluid of allogenic recharge related to the later fills is the main lateral freshwater flow dominated by external runoff from the catchment in the setting of the horst-lowland within the rifting basin, induced by the Yanshanian destruction of the North China Craton. Finally, the relationship between the three fracture families and two kinds of related fluids is revealed. This allows us to propose a model to understand the polyphase-superimposed fracture-related karst reservoir complexes within the deep carbonate basement of tilting fault blocks that neighbour the Bozhong hydrocarbon kitchen and predict the formation of potential plays with high accuracy.

Effective use of limestones to reconstruct seawater Li isotope compositions - A community standard proposal

Past variations in lithium concentration and isotope ratio of seawater recorded in marine carbonates have shown great potential in tracing carbon cycles during critical climate transitions, especially coupled with the radiogenic strontium isotope system. However, acquiring reliable seawater Li isotope compositions from marine carbonates can be technically challenging because non‑carbonate phases co-existed in ancient marine carbonates can easily contaminate carbonate Li signal during inappropriate sample dissolution. Each contaminant phase, including Mn oxides, clays, and silicate minerals, can have different Li isotope compositions than that preserved in the carbonate lattice. More importantly, a significant portion of Li is adsorbed on the Mn oxides and clay minerals. This fraction is considered exchangeable and can be liberated using weak acid without destruction of mineral structure. Cleaning procedures and partial digestion have been applied to remove the exchangeable Li fraction in contaminative phases and selectively dissolve the carbonates. However, previous methods cannot be directly applied to ancient marine carbonates of various carbonate purity, which lack systematic testing on the threshold of sample purity to maintain the efficiency of the precleaning and partial digestion. Here we report an efficient sequential leaching protocol to extract primary seawater Li and Sr isotope compositions from bulk marine carbonates. The procedure consists of pre-cleaning steps using 1 M ammonium acetate and 1 M ammonium carbonate to completely remove the exchangeable fraction, followed by partial digestion using 0.3 M acetic acid to selectively target carbonate-bounded Li. We validate this method by mixing carbonate and contaminant endmembers in different weight percentages. We found this protocol works effectively for carbonates of >80% purity. Additionally, we demonstrate filtration is necessary when separating leachates from the solids to quantitatively avoid contaminations from non‑carbonate phases. We also suggest NIST-SRM-1d to be a cross-lab carbonate standard for Li isotope analyses and report its long-term external precision (two years). To sum, we propose an effective community standard procedure to reconstruct δ7Lisw records using ancient bulk carbonate samples.

The Impact of Contact: Isotope Geochemistry Sheds Light on the Lives of Indigenous Australians Living on the Colonial Frontier in Late 19th Century Queensland

Here, we report the first attempt to use isotope geochemistry to improve understanding of the experiences of Indigenous Australians living on the colonial frontier in late 19th century CE Australia. In the study, we analysed strontium (87Sr/86Sr), carbon (δ13C), and oxygen (δ18O) isotope ratios from the tooth enamel and dentine of six individuals who died in Normanton, Queensland, in the 1890s. The study was a collaboration between scientists and the local Traditional Owners, the Gkuthaarn and Kukatj people, and was carried out to promote truth and reconciliation. The enamel 87Sr/86Sr results suggest that the individuals moved to Normanton from three geologically distinct regions during the period of European expansion into the Gulf of Carpentaria, Cape York. This is consistent with the oral histories and historical documents, which suggest that many Indigenous people in the Gulf Country were displaced to camps on the outskirts of towns like Normanton because of European settlement. The δ13C values we obtained indicate that the individuals mostly ate C4 plants and/or C4-plant-consuming herbivores. When combined with the fact that some of the individuals’ teeth had dental caries, this suggests that the individuals may have had regular access to introduced foods. The enamel δ18O values are high compared to an international comparative sample, at 0.72–4.69‰ VPDB. We suspect the elevated values are due to a combination of a high degree of preferential loss of 16O through evaporation of surface water, the amount effect associated with the Australian monsoon, and high prevalence of introduced infectious diseases. Together, the results of our study demonstrate that isotopic analysis of human remains has the potential to further illuminate the effects of European colonisation on Indigenous people in Australia. Perhaps most importantly in connection with this, our study’s results show that isotopic analyses of human remains can provide surprisingly detailed information about the lives of a category of Indigenous Australians who rarely appear in the documents written by early ethnographers and colonial officials—subadults. That the analysis of the skeletal remains of Indigenous Australians can now contribute to the truth and reconciliation process is an unexpected, interesting, and welcome development in the story of bioarchaeology in Australia.

Assessing the mobility of Bronze Age societies in East-Central Europe. A strontium and oxygen isotope perspective on two archaeological sites.

European Bronze Age societies are generally characterised by increased mobility and the application of isotopic methods to archaeology has allowed the rate and range of human travels to be quantified. However, little is known about the mobility of the people inhabiting East-Central Europe in the late Early and Middle Bronze Age (1950-1250 BC) whose primary subsistence strategy was herding supported by crop cultivation. This paper presents the results of strontium (87Sr/86Sr) and oxygen (δ18O) isotope analyses in the enamel of people buried in collective graves at the cemeteries in Gustorzyn and Żerniki Górne. These sites are located in Kujawy and the Nida Basin, a lowland and an upland region with clearly different environmental conditions, respectively. Both sites are classified as belonging to the Trzciniec cultural circle and were used between 16th and 13th centuries BC. Among the 34 examined individuals only an adult female from Gustorzyn can be assessed as non-local based on both 87Sr/86Sr and δ18O signatures in her first molar. This may indicate the practice of exogamy in the studied population but more generally corresponds with the hypothesis of limited mobility within these societies, as has previously been inferred from archaeological evidence, anthropological analysis, and stable isotope-based diet reconstruction. New and existing data evaluated in this paper show that the 87Sr/86Sr variability in the natural environment of both regions is relatively high, allowing the tracking of short-range human mobility. A series of oxygen isotope analyses (conducted for all but one individuals studied with strontium isotopes) indicates that δ18O ratios measured in phosphate are in agreement with the predicted modern oxygen isotope precipitation values, and that this method is useful in detecting travels over larger distances. The challenges of using both 87Sr/86Sr and δ18O isotopic systems in provenance studies in the glacial landscapes of temperate Europe are also discussed.

Characterizing eastern spruce budworm’s large-scale dispersal events through flight behavior and stable isotope analyses

Eastern spruce budworm moth (Choristoneura fumiferana (Clem.)) mass outbreaks have widespread economic and ecological consequences. A key explanation for the large-scale spread and synchronization of these outbreaks is the long-distance dispersal (up to 450 km) of moths from hotspots (high-density populations) to lower-density areas. These events have proved difficult to monitor because dispersal flights occur only a few times a year, have no consistent routes, and commonly used tracking methods (e.g., population genetics, mark-recapture, radio telemetry) are inadequate for this system. Confirming immigration and distinguishing between local and immigrant individuals are crucial steps in identifying the physical and ecological drivers of moth dispersal. Here, we test whether isotopes of hydrogen (i.e., delta notation: δ2H) and strontium (i.e., strontium isotope ratios: 87Sr/86Sr), known to independently vary in space in a predictable manner, can be used to show that an immigration event occurred and to distinguish between local and immigrant adult spruce budworm moths. We used an automated pheromone trap system to collect individuals at six different sites in eastern Canada within and outside the current outbreak area of budworm moths. We first use moth flight behavior and time of capture, currently the best available tool, to determine putative local vs. immigrant status, and then evaluate whether individual 87Sr/86Sr and δ2H differ between putative classes. At two sites, we detect immigrant individuals that differ significantly from putative locals and thus confirm immigration has occurred. Saliently, sites where putative locals were sampled before the occurrence of potential immigration events (~10 days) showed the strongest differences between immigrant individuals’ and local 87Sr/86Sr and δ2H values. Sites where the collection of putative locals was close in time (hours) or following an immigration event (days) had a less-clear distinction between putative immigrants and locals, and showed signs of mixing between these two groups. We speculate that recent immigration could have led to the misclassification of immigrants as putative locals. 87Sr/86Sr and δ2H data generally support the adequacy of current approaches using capture-time to detect immigration events, and provide enhanced resolution to distinguish between local and immigrant individuals and to confirm an immigration event. We discuss the broader implication of adding isotopes to the toolkit to monitor spruce budworm dispersal and suggest next steps in implementing these tools.

The Miocene Climatic Optimum at the interface of epicontinental sea and large continent: A case study from the Middle Miocene of the Eastern Paratethys

The Miocene Climate Optimum (MCO) and the subsequent Miocene Climate Transition (MCT) are important biotic, environmental and geologic events. Here we address whether this holds true for the epicontinental Eastern Paratethys Sea (today's Black – Caspian Sea region). Two Tarkhanian – lower Chokrakian sequences of Middle Miocene age in the Kerch Peninsula were investigated using foraminifera, calcareous nannofossils, molluscs, fish otoliths, spores and pollen, oxygen and carbon stable isotopes and strontium isotope stratigraphy (SIS). Our results show that the marine environment during the Tarkhanian to early Chokrakian in the study area was characterized by open shelf conditions (near upper part of lower sublittoral zone), variable water column stratification and bottom water oxygen levels. Biostratigraphy and new SIS data suggest an age of >15.5 (∼16.0?) – 14.75 Ma for the Tarkhanian, which implies a considerably longer duration (> 0.75 Ma vs. 0.1 Ma) than was previously suggested. The maximum transgression seen in the middle Tarkhanian could be dated to ∼15.5–15.1 Ma and correlates with the highstand of sequence Bur 5/Lan 1 (15.2 Ma) and terminal phase of the MCO. The vegetation indicates a gradual change from subtropical humid (early Tarkhanian) to arid (early Chokrakian) conditions, which reflect the MCT. The climate change in the Eastern Paratethys occurred slightly earlier than in the Central Paratethys, possibly related to the existence of the large flat Eurasian continent.

Diagenetic and Biological Overprints in Geochemical Signatures of the Gigantoproductus Tertiary Layer (Brachiopoda): Assessing the Paleoclimatic Interpretation

Variations in the geochemical signatures of fossil brachiopod shells may be due to diagenesis and/or biological processes (i.e., 'vital effects'). It is critical to characterise them in order to identify reliable shell areas suitable for paleoclimate studies. This investigation contributes to an in-depth understanding of geochemical variations in Gigantoproductus sp. shells (SW Spain, Serpukhovian age), throwing light onto the Late Paleozoic Ice Age interpretation. Microstructural, crystallographic, cathodoluminescence and geochemical (minor and trace elements, δ18O, δ13C, and strontium isotopes) characterisations have been performed on the tertiary layer of the ventral valve, to assess the preservation state. Poorly preserved areas exhibit microstructural and geochemical changes such as recrystallisation, fracturing and higher Mn and Fe enrichment. Moreover, these areas have a higher dispersion of ⁸⁶Sr, ⁸⁷Sr, δ18O and δ13C than well-preserved areas. Three structural regions have been identified in well-preserved areas of the ventral valve by differences in valve curvature and thickness, such as the umbonal and thick and thin regions. These regions have different proportions of Mg, S, Na, δ18O, and δ13C, which are interpreted as 'vital effects' and probably related to growth-rate differences during shell growth. The Gigantoproductus tertiary layer seems the most suitable for paleoclimate studies, because it retains the original microstructure and geochemical composition.