Strontium Isotope Research Articles

Individual from the kurgan burial of the XII century in the Middle Oka — experience of complex archaeological and genetic research

For the first time, this paper presents a complex study of the burial of the ancient Russian woman from the classic “Vyatich” mound from the Kremenyie burial site (Moscow region). The mounds and synchronized ground cremation burials are combined at this unique 12th-century burial site. The aim of this research is to examine the historical details of the person from the mound using conventional archaeological, anthropological, and archae-oparasitology methodologies along with modern paleogenetics methods. The burial site is characterized by a general “archaic” rite, manifested in the late preservation of the cremation rite along with the burial. According to anthropological data, an elderly woman, over forty, was buried there. She was identified as a member of the local population by radiogenic strontium isotope (87Sr/86Sr) study. Rich grave content and the fact that the body was buried in the middle of the mound indicate the woman's high social standing in the community. According to ar-chaeoparasitological data, the eating habits of the woman appear to be characterized by the consumption of un-cooked or insufficiently thermally prepared freshwater fish. The complete mtDNA sequence reconstruction indi-cates that it belongs to haplogroup V1a1, one of the Western Eurasian haplogroup V branches. To date, this represents the first case of the V1a1 mitogroup being found in the Russian Plain during ancient times. A repre-sentative of the Danish Viking clan from the Oxford burial site of the XI century was the closest of the ancient samples to the mtDNA of the studied woman, which indicates a genetic relationship on the maternal lineage with the medieval Northwestern European population. Single nucleotide substitution A7299G in the mitogenome of the woman clusters her with present-day Russians from the Belgorod and Pskov regions and shows the continuity of the modern Russian population with the Ancient Russians. Thus, the results of our study demonstrate the private details of the individual as common historical features, which include the ceremonial side of burial and belonging to the maternal genetic lineage preserved in the modern gene pool of the Russian population.

Reconstructing the depositional environment and diagenetic modification of global phosphate deposits through integration of uranium and strontium isotopes

The geochemistry of phosphate rocks can provide valuable information on their depositional environment and the redox condition of global oceans through time. Here we examine trace metal concentrations and uranium (δ238U, δ234U) and strontium (87Sr/86Sr) isotope variations of marine sedimentary phosphate rocks and the phosphate-bearing carbonate fluorapatite (CFA) mineral phase, originating from Precambrian to mid-Miocene aged major global phosphate deposits. We find elevated concentrations of several trace elements (Al, V, Cr, Cd, U, Mn, Co, Cu, As, and Rb) in the CFA mineral phase of young phosphate rocks (Miocene to Late Cretaceous) relative to those of older (Devonian to Precambrian) rocks. The δ238U of phosphate rocks of Mid-Miocene to Permian age range from −0.311‰ to 0.070‰, exhibiting a positive fractionation relative to modern seawater (−0.38‰). This is similar to the isotope fractionation reported for carbonate and shale sediments, likely resulting from the reduction of uranium in porewaters during CFA precipitation. Cambrian to Precambrian phosphate rocks have lower δ238U of −0.583‰ to −0.363‰, indicating different depositional redox conditions likely resulting from seafloor anoxia and/or diagenetic modification. The 87Sr/86Sr ratios of phosphate rocks of Cretaceous to Mid-Miocene age generally follow the secular 87Sr/86Sr seawater curve. Phosphate rocks with 87Sr/86Sr that deviate from this curve have characteristic trace metal trends, such as lower Sr/Ca and Sr concentrations, suggesting later diagenetic modification. Older phosphate rocks of Precambrian age are systematically more radiogenic than the expected secular Sr seawater composition at the time of deposition, possibly due to the greater influence of terrestrial input in peritidal zones and/or more pervasive diagenetic modification. Overall, our study reveals connections between U and Sr isotope variations for reconstructing the depositional and diagenetic conditions of global phosphate rock formation through Earth history and the transition to an oxic ocean following the Paleozoic Oxygenation Event.

Spatial variability in water strontium isotopes and trace metals from the Clarence River Basin, New South Wales, Australia

Understanding fish movement in river systems is essential in identifying habitats which are important for species to perpetuate. Water chemistry, paired with fish otoliths, can be used to trace movements among different habitats, although a detailed understanding of spatial variation in water chemistry is first required. To obtain this knowledge, we analysed surface water collected from 59 sites throughout the Clarence River Basin, a coastal river basin in northern New South Wales, Australia. The primary objective was to quantify the spatial variation of trace metals and strontium isotope ratios (87Sr:86Sr) for future and paired use with otolith microchemistry to track fish movement. Using ICP-OES, we identified that some trace metals, particularly strontium and barium as well as 87Sr:86Sr ratios, varied spatially when analysing all water samples and revealed three distinct regions centring around the estuary, interior and outer regions. These differences were driven by variation in the underlying surface geology between the Clarence–Moreton Basin and the New England Block. Tidal influence also affected trace metals and 87Sr:86Sr ratios throughout the estuarine area. We suggest that the level of differentiation identified in the current study has the potential to discriminate broad-scale fish movements among regions/habitats using otolith analysis, with fine scale movements best elucidated using complementary techniques.

Resilient coral reef ecosystems: The case study of turbid-mesophotic coral buildups during the Late Oligocene Warming Event (Tertiary Piedmont Basin, NW Italy)

Nowadays, but also in the geological record, coral communities living in marginal conditions (i.e. low light, high turbidity, extreme temperatures, high nutrients and sediment input) are quite common and there is evidence that some of these reefs, often associated with mesophotic environments, may be more resilient to the current global warming trend, thus serving as possible ecological refugia.As an attempt to understand the response and resilience to past warming events of marine calcifying organisms, such as zooxanthellate corals of marginal reefs, herein we reconstruct the palaeoenvironment of an Oligocene mixed siliciclastic‑carbonate system in the Tertiary Piedmont Basin (NW Italy), where a suite of coral assemblages formed small buildups at the edge of a coarse-grained delta system. Geochronological dating by strontium isotope stratigraphy places the coral buildups in the middle Chattian, thus within the Late Oligocene Warming Event (LOWE): a crucial climatic event for coral reefs as characterised by substantial warming coincident with declining atmospheric CO2.The depositional model that we propose is ascribed to a fan-delta system, deposited within a narrow valley cutting through the metamorphic basement, where small and laterally discontinuous coral buildups grow-up in the prodelta setting, thus suggesting a mesophotic environment. In this context, the coral buildups appear to have been intermittently deactivated or smothered by fine-grained terrigenous input during flood phases or shifts in distributary channels until their final suffocation by fluvial sediments input.Within the coral buildups, the four distinguished coral facies (branching Stylophora floatstone, Acropora-Stylophora floatstone/rudstone, Goniopora/Caulastraea pillarstone, and mixed-coral domestone) are characterised in general by sediment-resistant corals and by specific taphonomic features.These coral facies shifted in time and space during the LOWE, highlighting the noteworthy adaptability and resilience of Oligocene corals to a complex interplay of environmental stressors such as turbidity, hydrodynamic energy, sediment and nutrient supply within a mesophotic setting.

Diagenetic evolution of Upper Cretaceous carbonate sequences (Sarvak Formation) in the Abadan Plain, Iran: evidence from petrographic, elemental, stable, and strontium isotopic data

ABSTRACT This study investigates the diagenetic evolution and geochemical variations within the Sarvak Formation by integrating the core, thin-section, scanning electron microscopy, X-ray diffraction, trace elements, carbon-oxygen, and strontium isotopic data from three wells in the Abadan Plain. The formation displays diverse diagenetic processes, influenced by multiple exposure surface condition including the Cenomanian-Turonian boundary (CT-ES) and middle Turonian (mT-ES). Meteoric diagenesis, shaped by tectonic activities and eustatic sea level changes, played a pivotal role, leading to dissolution (karstification), brecciation, cementation, and palaeosol formation. Geochemical analysis revealed significant elemental variations across the studied wells. Magnesium (Mg) exhibited peaks at sequence boundaries, responding to facies changes, while iron (Fe) and manganese (Mn) concentrations increased below disconformities, reflecting changes in redox conditions and karstification. Sodium (Na) concentrations varied with facies changes, showing peaks at sequence boundaries, indicative of palaeoexposure events. Strontium (Sr) isotopes aided in delineating stratigraphic positions of palaeoexposure surfaces and absolute dating of sequences. Increases in87Sr/86Sr ratios below disconformities suggested subaerial exposure events, with shorter durations at CT-ES and longer durations at mT-ES, contributing to dissolution features development. The δ13Ccarb and δ18Ocarb values indicated severe meteoric diagenesis below sequence boundaries, characterized by dissolution and reprecipitation of calcium carbonate as low-magnesium calcite (LMC) cements. Cross plots of δ13Ccarb vs. δ18Ocarb displayed inverted-J patterns, indicative of meteoric diagenesis effects. Comparison with previous studies highlighted similar trends in geochemical variations, with notable differences in element concentrations between wells. This study enhances our understanding of diagenetic history of the Sarvak Formation in the Abadan Plain and, in a larger scale, provides insights into diagenetic evolution of palaeoexposure-related carbonate sequences.

The evolution history of the early Eocene transient transgression in the Kuqa Depression: Evidence from strontium isotopes

The evolution history of the early Eocene transient transgression in the Kuqa Depression: Evidence from strontium isotopes

Biomolecular evidence reveals mares and long-distance imported horses sacrificed by the last pagans in temperate Europe.

Horse sacrifice and deposition are enigmatic features of funerary rituals identified across prehistoric Europe that persisted in the eastern Baltic. Genetic and isotopic analysis of horses in Balt cemeteries [1st to 13th centuries CE (Common Era)] dismantle prevailing narratives that locally procured stallions were exclusively selected. Strontium isotope analysis provides direct evidence for long-distance (~300 to 1500 kilometers) maritime transport of Fennoscandian horses to the eastern Baltic in the Late Viking Age (11th to 13th centuries CE). Genetic analysis proves that horses of both sexes were sacrificed with 34% identified as mares. Results transform the understanding of selection criteria, disprove sex-based selection, and elevate prestige value as a more crucial factor. These findings also provide evidence that the continued interaction between pagans and their newly Christianized neighbors sustained the performance of funerary horse sacrifice until the medieval transition. We also present a reference 87Sr/86Sr isoscape for the southeastern Baltic, releasing the potential of future mobility studies in the region.

Strontium isotopes and rare earth elements in terrestrial hot-spring deposits: Characterization and geothermal implications

Identifying geothermal reservoir rock types is fundamental in geothermal exploration, but the absence of active surface geothermal manifestations (especially hot springs) in blind geothermal systems makes this identification difficult. Nevertheless, blind geothermal systems may develop early-formed hot-spring deposits. As (bio-)chemical precipitate, these deposits may retain geochemical signatures of spring waters and thus provide insights into reservoir rock types. To assess their geothermal implications, the 87Sr/86Sr and rare earth elements + yttrium (REE + Y) characteristics of hot-spring deposits in two geothermal systems were investigated and compared with those of their reservoir rocks. Results showed relatively uniform 87Sr/86Sr values in hot-spring deposits within each system, but occasional 87Sr/86Sr contamination induced by exogenous detritus input was also observed. The amount of detritus input relates to the potential for interaction with surrounding soils/rocks and is thus environmentally controlled. Hot-spring deposits with high Sr concentrations showed greater 87Sr/86Sr contamination resistance than those with low Sr concentrations, revealing the influence of Sr concentration in hot-spring deposits on detrital 87Sr/86Sr contamination. The detritus input also influenced the REE + Y signatures of the hot-spring deposits, underscoring the necessity of contamination assessment before geochemical interpretation. Excluding samples with significant 87Sr/86Sr and/or REE + Y contamination, the remaining samples closely mirrored their respective reservoir rocks in terms of 87Sr/86Sr, with partial overlap in REE + Y signatures. This suggests that the 87Sr/86Sr and REE + Y characteristics of hot-spring deposits provide valuable insights into reservoir rock types. However, variations in 87Sr/86Sr or REE + Y compositions between some hot-spring deposits and corresponding reservoir rocks indicate additional influencing factors beyond reservoir rock types. Therefore, a comprehensive understanding of reservoir rock types requires integrated geochemical characterization, probably including 87Sr/86Sr, REE + Y, and other parameters. These findings underscore the potential of geochemical characterization of hot-spring deposits for identifying geothermal reservoir rock types, and this geochemical approach can complement geological and geophysical data to improve exploration efficiency, especially in blind geothermal systems.

Structural study of strontium-containing iron-phosphate glasses for radioactive waste vitrification

Iron-phosphate glasses are a wide group of materials with a wide range of applications. Among others, they are promising materials in toxic waste vitrification because of their high chemical durability and relatively low processing temperature and time. They are a novel group of glasses that are considered in the vitrification of radioactive waste, especially those that cannot be treated using conventional borosilicate ones. Since strontium isotopes are one of the main fission products present in the waste, the influence of Sr on the structural properties of the glasses is an important factor.Strontium-containing iron-phosphate glasses were subjected to structural studies using FT-IR and Raman spectroscopies. The obtained spectra were described, and appropriate band assignments were done. Based on the research conducted, the structural features of the phosphate network and their changes were determined.The results obtained showed that strontium in relatively low content up to 20 mol% acts as the glass network charge compensator and can stabilize the network. Above this threshold, SrO can be treated as a pure modifier, leading to gradual depolymerization. Thus, this point may be treated as the maximum waste loading for effective strontium immobilization.

Tracing the Environmental Effects of Mineral Fertilizer Application with Trace Elements and Strontium Isotope Variations

Tracing the Environmental Effects of Mineral Fertilizer Application with Trace Elements and Strontium Isotope Variations

Uranium-series and strontium isotope systematics in soil carbonates from dryland Critical Zones: Implications for soil inorganic carbon storage and transformation

Soil carbonates are dominantly present in dryland Critical Zone (CZ) and their formation could lead to important long-term carbon sequestration in arid to semiarid soils if the Ca ions were derived from silicate weathering or other non-carbonate sources. In managed CZ systems such as agricultural areas converted from natural drylands, irrigation has profound effects on the dryland CZ inorganic carbon storage, especially by modifying dissolution and precipitation dynamics of soil carbonates via controls of irrigation intensity and water chemistry, soil properties, and hydrological flow paths. These processes could lead to transformation of inorganic carbon in soils and groundwater aquifers underneath drylands. One key knowledge gap in studying soil carbonates from managed dryland CZ systems is to detect the formation of soil carbonates under irrigated conditions and distinguish them effectively from soil carbonates formed under natural conditions.Here, we explore the potential of using U-series and strontium isotopes to investigate the formation timescales and conditions of soil carbonates in both natural and managed dryland CZ in Chihuahua Desert of American Southwest. We obtained new U-series and Sr isotope ratios from mature stage V natural soil carbonates in the Jornada Basin of southern New Mexico and compared to previously published U-series and Sr isotope results for younger Jornada soil carbonates as well as irrigation impacted soil carbonates from the Rio Grande floodplains in west Texas. Specifically, we applied the U-series dating method (238U-234U-230Th) to estimate the timescales of soil carbonate formation under both natural climatic conditions and impacts of modern agriculture irrigation. In addition, we showed that the initial (234U/238U) activity ratios recorded in these soil carbonates reflect the systematic changes of soil infiltration rates in both natural and managed dryland CZ. We also utilized Sr isotope ratios (87Sr/86Sr) in soil carbonates, dust, and irrigation water to trace the Ca sources in soil carbonates from natural and managed dryland CZ. Soil carbonates from both settings were characterized by slightly radiogenic 87Sr/86Sr ratios, consistent with their potential of long-term carbon storage in drylands.U-series and Sr isotope systematics characterize important differences in soil carbonates from natural and managed dryland CZ with respect to their Ca sources, timescales of carbonate formation and transformation, and availability of soil moisture. Soil carbonates formed, accumulated, and transformed in natural drylands with long time scales but under irrigated arid agricultural areas its formation is significantly modified by irrigation and other agriculture practices, with implications for long- and short-term inorganic carbon sequestration in both systems of drylands.

Hydroclimate of the Messinian Salinity Crisis constrained from paleo-water triple oxygen, hydrogen, and strontium isotopes

Giant evaporite deposits formed during the Messinian Salinity Crisis (MSC) in the Mediterranean Sea during the upper Miocene. The primary cause is a restricted Atlantic-Mediterranean connection, but the detailed hydroclimate evolution of this event is still a matter of debate. Here we reconstruct the triple oxygen and hydrogen isotopic composition of paleo brines from structurally bonded water in Messinian gypsum from Cyprus. A two-stage evaporation model is constructed to best approximate the hydrological conditions at which Messinian gypsum formed in marginal basins of the Mediterranean Sea. Subsequently, hydroclimatic parameters like paleo relative humidity (RH) are modelled using an iterative curve fitting isotope model approach. The results of our limited dataset reveal a slightly lower RH during the third compared to the second stage of the MSC. This apparent drop in RH is consistent with previous observations from the literature.Besides absolute values of RH, our model allows reconstructing the triple oxygen and hydrogen isotopic composition of the open Mediterranean Sea. This provides an estimate for the proportions of continental water vs. Atlantic seawater flowing into the basin, serving as a proxy for the size of the strait of Gibraltar. The model implies a continental water fraction of around 75–81 % both for the second and third stage of the MSC. In addition, we determined the 87Sr/86Sr of our samples to: i) confirm their stratigraphy; and ii) estimate the relative proportion of continental water vs. Atlantic seawater entering the Mediterranean using Sr mass balance calculations. The combined oxygen and Sr isotope records indicate a persistent connection to the Atlantic supporting the hypothesis that the striking drop in 87Sr/86Sr at the beginning of MSC stage 3 is mainly related to an increased contribution of continental water with low 87Sr/86Sr and high Sr concentrations from the Paratethys. Our results show that the combination of triple oxygen, hydrogen, and Sr isotope data provides a powerful tool to disentangle paleo-hydroclimate even in such complicated hydrological settings as the Mediterranean Sea during the MSC.

Unveiling Hunnic legacy: Decoding elite presence in Poland through a unique child’s burial with modified cranium

This article presents a double burial from Czulice indicating elements of the Hunnic culture. Individual I, aged 7–9, and Individual II, aged 8–9 with a skull deformation, were both genetically identified as boys. Individual II, who exhibited genetic affinity to present day Asian populations, was equipped with gold and silver items. In contrast, Individual I displayed European ancestry. The application of strontium isotope analysis shed light on the origins of the individuals. Individual I was non-local, while Individual II was identified as a local, but also falling within the range commonly associated with the Pannonian Plain. Stable isotope analysis suggested a diet consisting of inland resources. Through radiocarbon dating, this burial was determined to date back to the years 395–418 CE, making it the earliest grave of its kind discovered in Poland. The analyses have provided new insights into the nature of the relationship between the Huns and the local inhabitants.

Preliminary strontium isotope (87Sr/86Sr) baselines for the Bjäre Peninsula and Halland in southern Sweden

During the last decade, the application of strontium isotope analysis (87Sr/86Sr) has increased rapidly. The understanding of the strontium isoscape and the construction of a strontium isotope baseline in southern Scandinavia are biased toward Denmark and southwestern to eastern Scania. We report the results of new baseline samples in Halland and the Bjäre Peninsula, adding to the rich strontium isotope library that exists for southern Scandinavia. We add nuance to the previous divisions of Scania, in which the Bjäre Peninsula is not well represented. The results show that the Bjäre Peninsula is characterized by relatively low 87Sr/86Sr values gathered in the preliminary baseline 0.7100 ± 0.0024 (2σ, n = 8), similar to that of southwest Scania and Zealand in Denmark. There is a greater variation and higher values among the Halland samples. Together with previously published faunal samples, a preliminary 87Sr/86Sr baseline for Halland is 0.7122 ± 0.0055 (2σ, n = 24). We apply these baseline results to archaeological cases, both human and animal, from recent excavations in the Bjäre Peninsula. The results imply that there was a certain degree of mobility and interaction across the landscape in this region of southern Scandinavia in prehistory.

In-Situ Geochemical and Rb–Sr Dating Analysis of Sulfides from a Gold Deposit Offshore of Northern Sanshandao, Jiaodong Peninsula, North China: Implications for Gold Mineralization

The gold deposit offshore of Northern Sanshandao is an ultra-large-scale gold deposit discovered in the Jiaodong ore area in recent years. This deposit is a fractured-zone altered-rock-type gold deposit; however, its ore genesis and precise mineralization processes are still highly controversial. Based on petrographical observation, the trace elements, sulfur isotopes, and rubidium–strontium isotopes of the gold-bearing pyrite were analyzed using LA-MC-ICP-MS to obtain the source of the ore-forming fluids and ore genesis. The results show that Au has a good positive correlation with Ag, As, and Cu. It is speculated that the As in the pyrite of the gold deposit offshore of Northern Sanshandao is in the form of As−, replacing S− and entering the pyrite, causing its lattice defects, and thus promoting the entry of Au+ into the gold-bearing pyrite. The Co/Ni ratios mainly range between 0.1 and 10, indicating that the mineralization process has experienced different forms of hydrothermal evolution and the mixing of different fluids. The results of the in-situ sulfur isotope analysis show that pyrite δ34S in the mineralization period is characterized by a high sulfur value. The authors of this study believe that the initial sulfur isotope composition has mantle-derived components. The large-scale, deep cutting, and high degree of fragmentation in the Sanshandao fault zone are conducive to the interaction between fluids and rocks, as well as the mixing and addition of seawater, resulting in the characteristic high δ34S value. The Sr isotopic compositions indicate a crust–mantle mixing attribute of the mineralized material source. The Rb–Sr isochron age of the pyrite is 118.5 ± 0.65 Ma, which represents the age of gold mineralization. According to the characteristics of the trace elements and sulfur isotopes, it is inferred that the gold deposit minerals offshore of Northern Sanshandao originated from deep magmatic-hydrothermal reservoirs, and the mixing of seawater and Au–As-rich hydrothermal fluids was the formation mechanism of huge amounts of gold precipitation.

The Hydrogeochemistry of and Earthquake-Related Chemical Variations in the Springs along the Eastern Kunlun Fault Zone, China

The Eastern Kunlun Fault (EKF) is situated in an area with a history of significant seismic events, yet it has witnessed a dearth of major earthquakes in recent years. This study conducted a detailed analysis of the hydrogeochemical characteristics of the springs in the EKF and their temporal variation, aiming to address the gaps in the research on the hydrogeochemistry in the region and to investigate the changes in water chemistry during the seismogenic process. In this study, the main elements, trace elements, hydrogen isotopes, oxygen isotopes, and strontium isotopes of 23 springs in the EKF were analyzed. The results indicated that the groundwater recharge in the eastern part of the Eastern Kunlun Fault Zone mainly originates from atmospheric precipitation, as supported by its isotopic characteristics. The spring water is immature, showing weak water–rock interactions. A hydrochemical analysis classified the springs into 11 main types, reflecting varying degrees of water–rock interaction. Based on measurements using quartz geothermometers, the estimated geothermal reservoir temperatures ranged from 39.6 to 120.3 °C, with circulation depths of 1.3 to 3.8 km. By means of regularly monitoring three selected springs, this study also explored the relationship between earthquakes and hot spring chemical variations. Finally, a conceptual model of hydrogeochemistry was proposed to describe the groundwater circulation in the study area.

The First Data of Strontium Isotopic Composition of Osteological Material from Late Bronze to Early Iron Age Settlements in the Crimea Region

The First Data of Strontium Isotopic Composition of Osteological Material from Late Bronze to Early Iron Age Settlements in the Crimea Region

Strontium isotope stratigraphy of marine Oligocene–Miocene sedimentary successions of Kutch Basin, western India

The Kutch Basin of western India exposes one of the most complete, fossiliferous marine Cenozoic sedimentary sequences of India. Precise depositional ages of these sequences are of great importance in the reconstruction of palaeoclimatic and palaeobiogeographic histories of the basin. Due to the poorly constrained foraminiferal biostratigraphic ages, we conducted high‐resolution 87Sr/86Sr chronology of the various fossiliferous, stratigraphically continuous units of Oligocene–Miocene strata in Kutch Basin. Besides updating the previously determined 87Sr/86Sr chronology, we report new numerical depositional ages for Oligocene–Miocene formations and members, and correlated these ages to the existing biostratigraphic schemes. The new 87Sr/86Sr data indicates a depositional age range between 28.64 + 0.29/‐1.11 and 23.51 + 1.53/‐1.85 Ma (Rupelian‐Chattian) for the Maniyara Fort Formation, between 23.07 + 0.94/1.39 and 18.09 + 0.24/‐0.57 Ma (Chattian‐Burdigalian) for the Khari Nadi Formation, and between 15.11 + 0.56/‐2.87 and 12.29 + 1.22/‐1.9 Ma (Langhian‐Serravallian) for the Chhasra Formation. The sedimentation rate, determined through numerical ages derived from 87Sr/86Sr, indicates an increase in sedimentation for the Khari Nadi (0.23 ± 0.04 cm/kyr) and Chhasra (0.12 ± 0.04 cm/kyr) formations, likely related to uplift of the Himalaya‐Tibetan plateau and intensification of the Indian Summer Monsoon. The bulk sediment element ratios (V/Ni, Ni/Co and V/Cr) indicate oxic to suboxic palaeo‐redox conditions during deposition of the Oligocene–Miocene successions of the basin. Based on new and updated 87Sr/86Sr chronology, the depositional environments and sedimentation rates of the Kutch sequence are correlated with changes in sea‐level, sedimentation rates in the Arabian Sea and Bay of Bengal, and the global climate changes across the Oligocene–Miocene boundary.

Assessing Recharge Sources and Seawater Intrusion in Coastal Groundwater: A Hydrogeological and Multi-Isotopic Approach

One of the crucial challenges of our time is climate change. The consequences of rising sea levels and drought greatly impact water resources, potentially worsening seawater intrusion. Characterizing coastal aquifers is an essential step in devising strategies to address these phenomena. Seawater intrusion poses a critical socio-economic and environmental issue in the coastal plain of Muravera, southeastern Sardinia (Italy). This coastal plain is an important agricultural area in Sardinia, and the health of the crops is compromised by the increasing salinization of shallow groundwater. To enhance our understanding of the hydrogeological conceptual model, which is essential for a sustainable resource management system, hydrogeological investigations were conducted and complemented by the chemical and multi-isotopic analyses of groundwater. The main objectives of this study were to identify groundwater recharge areas, understand salinization mechanisms and trace the evolution of water chemistry. Within this framework, a monthly survey monitoring piezometric level and electrical conductivity was carried out for one year. This survey was integrated with chemical and isotope analyses, including δ18OH2O and δ2HH2O, δ11B, δ18OSO4, δ34SSO4, and 87Sr/86Sr. Hydrochemistry analysis results revealed the occurrence of seawater–freshwater mixing, extending up to 4 km inland. H2O isotope analysis confirmed the mixing processes and indicated the meteoric origin of recharge waters for both shallow and semi-confined aquifers. The strontium isotopes ratio facilitated the identification of four main groundwater flow paths, confirmed by the SIAR model. The results of this combined hydrogeological–geochemical–isotopic survey provide essential elements for the future implementation of an integrated and sustainable management system. These findings enable interventions to slow the process of seawater intrusion and meet the economic needs for the development of local communities.

Assessing the Utility of Strontium Isotopes in Fossil Dental Calculus

Strontium (Sr) isotopes measured in fossil remains have been a useful tool to assess the geographical origin and even migrations of humans and other animals. In particular, dental enamel generally represents the ideal material, as it is dense and less prone to diagenetic replacement of Sr post-burial. However, fossil teeth can often be precious artefacts and difficult to access for destructive analysis. Here, we assess whether measuring Sr isotopes in fossil dental calculus could be used at least as a rangefinder to determine the geographical origin of an individual. We measured trace element concentrations in modern calculus (from a local dental practice), and trace element concentrations and 87Sr/86Sr ratios in human fossil calculus, dentine, and enamel from specimens collected in York, UK. Comparing trace element concentrations between modern and fossil calculus show that metals present in fossil calculus are mostly acquired post-burial, including Sr. The relationship between 87Sr/86Sr and Rb/Sr ratios in fossil calculus, dentine, and enamel suggests that the diagenetic end member would have a 87Sr/86Sr ratio consistent with the one modelled for the York region, but a low Rb/Sr. Without calculus data, dentine and enamel data would have probably suggested a lower 87Sr/86Sr ratio for a diagenetic end member, expecting high Rb/Sr values. Thus, while Sr isotopes in fossil calculus may not be useful to identify the geographical origin of an individual, they may be useful in constraining the composition of the diagenetic end member. Combining Sr isotopes in fossil dental calculus and enamel could be a more robust approach to identify geographical origin than using enamel alone.