During the Bronze and Iron Ages, large parts of western, southern and southwestern Iran were under the influence of the Elamite polity. Over the past two decades, excavations at the cemeteries of Deh Dumen, Lahsavareh, and Lama have revealed significant evidence dating to the Elamite period. Archaeological data indicate that these cemeteries were used over extended periods of time. To establish a more precise chronology for these cemeteries, six human bone samples from the Deh Dumen and Lahsavareh cemeteries were subjected to radiocarbon (14C) dating. In addition, one radiocarbon date from the Lama cemetery has previously been published. The oldest evidence of settlement at Deh Dumen dates back to the Proto-Elamite period, for which a date between 3200 and 2800 BCE can be suggested based on comparisons of pottery with sites from the same period for which absolute dates are available. The new 14C results show that the oldest graves identified at Deh Dumen can be dated to between 2500 and 2200 BCE, corresponding to the Old Elamite period. Then, from about 1400 to 1100 BCE, burials took place in the two cemeteries of Deh Dumen and Lahsavareh, which coincides with the Middle Elamite period, and finally, burials were carried out again in these two cemeteries from about 800 to 600 BCE during the Neo Elamite period. Although only one 14C date has been published from Lama, showing a date of ca. 1600–1450 BCE, comparing its findings with those from Lahsavareh and Deh Dumen suggests that this cemetery was also used as a cemetery for a long period in the second millennium and the first half of the first millennium BC. Absolute dating carried out in these cemeteries allows to separate and date the cultural materials of the Old, Middle, and Neo Elamite periods in the Zagros highlands more precisely.

Radiocarbon (14C) activity in aquatic environments is usually different from that of the atmosphere, the result being that organisms that grow in these different environments will have different 14C ages, even though they are contemporary. This age offset in marine samples is known as the “marine reservoir effect.” The marine calibration curve takes this effect into account as a global approximation, but local variations due to ocean dynamics and other factors must be individually studied and corrected for. With a littoral of more than 11,000 km and a great interest in dating malacological marine samples, Mexico has scarce local reservoir effect studies. Most of the available data come from studies done in the 1960s and 1990s. In this study, we present new reservoir effect corrections for four sites in the Pacific Ocean with positive ΔR values as expected, and one from the Caribbean Sea with a negative average value of ΔR. The results were obtained by dating known-age shells from the malacological collection of the Natural History Museum Felipe Poey, in Havana, Cuba. This new data will be useful to do more precise reservoir effect corrections to malacological samples of the region, with special interest in contexts where it is difficult to date other kinds of organic samples, due to difficulties in their preservation.

Radiocarbon dating is essential for establishing robust chronologies in archaeological and paleoenvironmental contexts spanning the last 55,000 years. Pottery, pervasive in the archaeological record, offers a crucial framework for dating human activity during the Holocene. Traditionally, radiocarbon dating of pottery has relied on targeting carbonaceous inclusions such as organic temper or measuring stratigraphically associated materials like bone and charcoal. Inaccuracies can arise, however, if the targeted fraction does not reflect the timing of vessel use or if stratigraphic associations are uncertain. An alternative involves radiocarbon dating of lipid residues, particularly fatty acids absorbed into the ceramic matrix during the processing and storage of plant and animal-derived resources. This approach holds promise for delivering highly accurate measurements directly correlating to vessel use. At the Oxford Radiocarbon Accelerator Unit, efforts have been made to develop this methodology through compound-specific radiocarbon dating of pottery, employing a gas chromatography (GC)-preparative fraction collector (PFC) approach. Here, we describe the protocol and present preliminary findings, including analyses conducted on pottery samples sourced from an archaeological site with an established chronology.

The date of the Thera eruption has been a subject of intense debate since the mid-20th century. In recent years, the disagreements have escalated with the introduction of IntCal20. The increased number of annual measurements around the time period of the eruption has highlighted potential fluctuations in the atmospheric radiocarbon record, shedding new light on the date of the disastrous event. The Centre for Isotope Research in Groningen has already contributed data from this time period to IntCal20, and here, we report a new set of annual data of approximately 90 radiocarbon measurements between 1660 and 1507 BCE. We investigate the potential anomalies in the calibration curve and compare our dataset with those from other leading laboratories. Although we do not find compelling evidence of any rapid increases in radiocarbon production during this period, the results do point to the presence of minor differences between datasets which could be species, region or laboratory pretreatment related. By quantifying such offsets, we assess their impact on chronological models related to the eruption of Thera.

The natural variability of atmospheric 14C has been significantly altered by anthropogenic activities linked to technological advancements and energy consumption over the past two and a half centuries. The Suess effect, a consequence of the combustion of old carbon (fossil fuels) since the mid-18th century and the bomb peak from the mid-20th century’s thermonuclear tests, has obscured the natural 14C signal in the atmosphere. This study presents a 14C analysis of leaves, flowers, and grass collected from various locations worldwide. Over the last 10 years, more than 150 samples have been collected and used as materials for experiments conducted by students in physics lab classes (Department of Physics, ETH Zurich) or as part of school projects. Short-lived vegetal fragments are ideal material for teaching radiocarbon dating and demonstrating our research. The collection of data presented here underscores the sensitivity of radiocarbon analysis for detecting fossil carbon components. Trees from urban sites worldwide demonstrate a dilution of the atmospheric 14C concentration of 2–3%. Trees growing close to busy roads and traffic show a dilution of up to 10%. Moreover, the data show a fading trend of the bomb peak observed from 2015 to the present, as well as the direct impact of fossil CO2 on the 14C concentration of the living biota around us.

The Nerja Cave is a key archaeological site in the Southern Iberian Peninsula. It was inhabited by humans from the Upper Palaeolithic until recent Prehistory (30 and 3.7 ka cal BP). Various excavation campaigns performed in its external chambers (Vestíbulo, Mina and Torca) have recovered evidence of its use as habitat and burial site. Multiple studies on these matters have been published, but, until now, no Bayesian chronological modeling that utilized radiocarbon dates of the three chambers has been performed. To do so, all the available radiocarbon dates and stratigraphic and archaeological data have been compiled. These comprehend ample and diverse information about which, firstly, individual phase models based on the stratigraphic sequence of each one of the chambers have been created. After critically evaluating the results for each of the chambers, a general phase model for the prehistoric occupation of the external chambers has been created considering the cultural adscription of the samples. This has enabled the identification of 11 phases which correspond to the different technocomplexes of the Gravettian, Solutrean, Magdalenian, Epipalaeolithic, Mesolithic, Neolithic and Chalcolithic. Still pending are the refinement and improvement of the model for the Neolithic horizon among other phases of the sequence. The individual and the general models have evidenced important differences between the different archaeological phases in radiocarbon information as well as in the occupation of the three chambers.

This study presents the initial results of carbon-14 dating after performing sample preparation and graphite production processes at the Federal University of Bahia (UFBA) in an intercomparison with the same processes performed at the Radiocarbon Laboratory of the Fluminense Federal University (LAC-UFF). Both laboratories are located in Brazil. The accelerator mass spectrometry (AMS) system at LAC-UFF was used for radiocarbon measurements. To verify any possible contamination sources during sample preparation, we initially performed swipe tests at UFBA, which were subsequently processed and the graphite samples were produced at LAC-UFF. After UFBA, several reference materials (IAEA-C1, -C2, -C6, -C9, and OXII standards) were prepared and converted into graphite. In addition, the sample material was first partially prepared at UFF and UFBA and then analyzed with the AMS system at LAC-UFF. Subsamples were prepared for additional measurements of the δ13C composition with an elemental analyzer coupled to an isotope ratio mass spectrometer (EA–IRMS) in LFNA-UFBA to study the isotopic fractionation and yield of the graphitization reaction. The obtained values closely aligned with the reference values, demonstrating reproducibility and quality and indicating minimal contamination during chemical and graphitization processes. In the future, samples from different matrices will be prepared at UFBA for application in paleoenvironmental and archaeological studies.

The Benedictine Abbey in Tyniec is the oldest existing monastery in Poland (11th cent. AD). The historic walls of the Monastery have survived to this day and crown the limestone hill on the Vistula River. The geological structure of the surrounding area is reflected in the composition of the mortars.

In vicinity of Tyniec one may observe outcrops of Upper Jurassic limestones represented by two facies: bedded limestones with cherts and massive limestones. Recently, it was discovered that the monks not only fortified the Tyniec hill but also partly built it up with loess. Additionally, a massive “stepped” stone platform was later built to strengthen the edge of the hill. The mortars radiocarbon dating provides the first attempt to obtain the wide chronology of the extension of Tyniec. For this purpose, the chronologically oldest layers were analyzed.

Sequential dissolution of mortars was applied to separate the carbonates of different origin. The obtained results illustrated the huge influence of mortar components and the local geological structure on the 14C measurements. In addition to the mortar, 14C measurements were also made for charcoal from Tyniec Abbey. Radiocarbon dating was performed on the selected fractions using accelerator mass spectrometry (AMS). Radiocarbon dating results of samples from the oldest part of the stone platform make it possible to associate its construction with the earliest monastery buildings.

Improving our understanding of biochar carbon (C) stability in soil is crucial given its potential for soil C sequestration. However, challenges with isotopic labeling of biochar restrict our ability to determine its fate in soil. Atmospheric nuclear bomb tests in the 1960s resulted in a 14C spike in tree rings, providing an opportunity to address this challenge. Here, we present a method that utilizes the elevated levels of 14C in wood from tree rings formed between 1964 and 1967 as a tracer to determine the proportion of biochar C in mineralized soil. Biochar was produced using wood from the 14C enriched tree rings as feedstock and thereafter used in a mineralization experiment capturing the emitted CO2. We demonstrate that the bomb 14C-enrichment in the biochar is high enough to differentiate between CO2 originating from either biochar or soil organic matter mineralization. The method can be used to address questions on biochar persistence, its interactions with soil organic matter and research that is needed to explore the potential to use biochar for C sequestration in soils.

Travertine is widely distributed in northwestern (NW) Iran and Turkey and serves as a valuable sample for paleoenvironmental reconstructions in semi-arid areas. Previous studies have analyzed the chemical compositions, carbon and oxygen isotopes of the travertines in NW Iran for paleoenvironmental reconstructions, but little dating has been done because travertine 14C dating faces the problem of identifying the initial 14C concentration of each sample. The objective of this study is to determine the formation age of travertine in NW Iran using radiocarbon (14C) and δ13C from a travertine mound and its related spring water. Travertine samples were collected from the base to the top of a cone-shaped travertine mound, Zendan-e Soleyman, in the Takab region of NW Iran. The 14C concentrations of the travertine samples ranged from 0.67 to 3.72 pMC, with values fluctuating considerably and higher 14C being observed at higher elevations. The δ13C values were lower at higher elevations (+10.1 to +7.4‰) with fluctuations. The values suggest that the travertines were formed through the decarbonation of limestone and rapid degassing. The dissolved inorganic carbon (DIC) of nearby spring water samples had 14C concentrations of about 10.4 pMC, about 89.6% dead carbon fraction (DCF), and δ13C value of +1.3‰. These values indicate that one of the of CO2 sources in the travertine-deposited spring water was of hydrothermal origin. Considering the DCF of the spring water DIC, the formation of the travertine mound began about 20 kyr BP, and the growth of the mound ended about 7 kyr BP.

Terrestrial gastropods can incorporate carbon from multiple sources, including 14C-depleted carbonate from limestone, known as the “Limestone Problem” (Goodfriend and Stipp 1983). This affects the reliability of 14C dating on terrestrial snails, and varies by species, habitat, and physiography, necessitating local validation studies. This study assessed whether two land snail taxa common in carbonate terrains of Florida (USA) accurately reflect atmospheric 14C concentration at the time of biomineralization, a necessary condition for accurate dating, or if they incorporate pre-aged carbon, leading to radiocarbon ages that are “too old.” Radiocarbon measurements were made on 11 modern, known-age specimens (collected 1967–2015) of the rosy wolfsnail (Euglandina rosea) and flatcoil (Polygyra spp.) snails, and results were compared to expected atmospheric values based on the Bomb21 NH2 calibration dataset (Hua et al. 2022). Specimens from carbonate terrains had significantly lower 14C activity than the contemporaneous atmosphere, while those from sandy terrains showed no such offsets. The magnitude of the offset varied by taxon. Flatcoils from carbonate terrains had the most unreliable dates, overestimated by 1350 ± 740 14C yr on average. Rosy wolfsnails from carbonate terrains had smaller offsets, overestimating by 270 ± 130 14C yr on average. The results suggest land snails from Florida will incorporate significant and variable amounts of pre-aged or “dead” carbonate in their shells if it is present in the landscape.

Pahñu is an archaeological site belonging to the Xajay culture, which inhabited north-central Mesoamerica in 350–1000 AD. Human burials contained in three pairs of contiguous cists were discovered inside a ceremonial structure at Pahñu during excavations conducted between 2019 and 2022. The walls of the cists separated groups of skeletal remains, so the stratigraphic units containing them did not overlap. Stratigraphically speaking, the six groups of remains could have been contemporary and each of the cists could have been used during periods of different durations. Therefore, the analysis of excavation data could not produce a precise temporal sequence of the events that took place in the cists. However, radiocarbon dating by accelerator mass spectrometry (AMS) of representative samples of bones, teeth, and charcoal, allowed us to refine the temporal sequence of their placement in each cist and thus have a better understanding of the funerary practices of the Xajay.

Radiocarbon dates have become a cornerstone in archaeological reconstructions of past population dynamics. The increasing reliance on large-scale radiocarbon databases, usually aggregated from diverse sources, however, raises persistent concerns about sampling bias, especially heterogeneous sampling intensity across sites. In this paper, we introduce a rescaling method that adjusts the frequency of dates in radiocarbon datasets in proportion to dwelling counts at the settlement level, using weighting and bootstrap resampling. Through a series of simulations, we show that this approach consistently yields probability distributions that more closely reflect hypothetical population trends, particularly in contexts with high inter-settlement variability in sampling intensity. We apply our method to archaeological data from two areas in Korea, the Yeongsan and Geum River Basins, during the Proto–Three Kingdoms (1C BC–AD 3C) and Three Kingdoms Periods (AD 4–7C). Results demonstrate that rescaled datasets offer significantly different interpretations of population organization and reconfiguration than those derived from original data. This study highlights the importance of addressing sampling heterogeneity in local-scale demographic research and suggests that rescaling is a valuable complement to existing bias-correction strategies in archaeological studies of demography.

Holocene environmental changes on the Paraty coastal plain in southeastern Brazil unfolded under dynamic sea-level fluctuations and shifting sedimentary regimes. Continental and marine palynomorph analyses, combined with calibrated radiocarbon dating from two sediment cores (JBS1 and JBS2), reveal a continuous depositional record spanning approximately 7800 to 1000 cal yr BP. Sandy mud and muddy sand sequences reflect variable coastal energy conditions through out the mid to late Holocene. Dinoflagellate cyst assemblages indicate a transition from open marine to marginal marine environments, with maximum marine influence between 7000 and 5000 cal yr BP. Terrestrial palynomorphs show a concurrent shift from grassland-dominated landscapes to mixed vegetation including ombrophilous forest taxa. A marked increase in pollen concentration in the upper stratigraphic layer suggests coastal progradation, enhanced continental input, and reduced marine influence during the late Holocene regression. Bayesian age-depth models demonstrate uninterrupted but variable sedimentation rates, with no evidence for erosional surfaces or depositional hiatuses. The results align with regional sea-level reconstructions and under score the role of transgressive-regressive processes and delta infilling in shaping vegetation dynamics. This integrated micropalaeontological and chronostratigraphic approach offers a robust framework for interpreting Holocene palaeoenvironmental evolution in tropical coastal settings.

Radiocarbon date frequencies are widely used to reconstruct temporal variation in human activity, with peaks and gaps in kernel density estimates (KDEs) often read as discrete episodes. Such readings usually lack explicit segmentation criteria and are sensitive to sampling variability, calibration-curve structure and smoothing choices. This paper proposes and evaluates a Monte Carlo KDE–minima procedure for descriptive segmentation of dated-event intensity. Calibrated posterior distributions for individual dates are sampled to generate an ensemble of KDEs on a fixed calendar grid; local minima are retained as pulse boundaries only when they occur in both the median KDE and its 95% envelope, making the rule explicitly dependent on bandwidth and smoothing scale.

Performance is assessed with two simulation designs. Level A operates in calendar time with three pulses plus background, varying sample size, pulse separation and bandwidth. Pulse width is fixed at 400 yr and separation ${\rm{\Delta }}$ is defined as the centre-to-centre distance between adjacent pulses. Level B incorporates full radiocarbon calibration under three setups (IntCal20, SHCal20 and Mixed) and compares the envelope rule with a naive single-KDE minima rule and a Poisson changepoint model for binned counts. The bandwidth range $h = 80$–120 yr is treated as a decision-relevant multi-century smoothing regime, not as an optimal selector. High probabilities of recovering the three-pulse structure arise only when episodes are widely separated ($ \sim 800$ yr) and supported by at least $ \sim 100$–200 dates. Calibration further degrades performance. Differences among curves are small relative to sample size, bandwidth and segmentation rule, indicating that curve choice is second-order at this scale. Conditional on correct pulse-count recovery, naive KDE typically places boundaries more tightly, but at the cost of substantially more over-segmentation. The envelope rule is therefore better understood as a low-risk device for suppressing unstable minima than as a precision estimator. Under the calibrated design examined here, the Poisson changepoint model systematically over-segments. The study sets quantitative limits on what KDE-based pulse detection can recover and provides a conservative rule for summarising broad episodes of dated activity rather than estimating population history directly.

Radiocarbon analysis of atmospheric particulate matter is a powerful tool for elucidating the apportionment of carbon sources. The radiocarbon content enables the differentiation between fossil-derived carbon, primarily from fossil fuel combustion, and modern carbon, associated with for example, biomass burning. Precise identification of anthropogenic and natural aerosol carbon sources is essential for establishing a robust framework to assess their impact on coastal ecosystems. In this work, we determined the contribution of fossil and modern carbon in aerosols collected in coastal areas of Mexico and Cuba. PM2.5 fraction was collected in the maritime ports of Veracruz and Manzanillo in Mexico, and PM10 fraction in Havana in Cuba. The analyses are complemented by elemental characterization and receptor modeling to discern specific contributions to PM mass. The wind climatology analysis was conducted using ERA5 reanalysis data, covering 30 years (1993–2023) and focusing on the summer months to characterize wind patterns at a height of 10 meters. To determine the meteorological conditions during the sampling campaign at the three locations, we have computed site-specific backward air-mass trajectories using the NOAA HYSPLIT model (GDAS meteorological fields). Fossil carbon is an important component of aerosols from maritime ports such as Havana and Veracruz. Manzanillo port exhibited reduced pollutant levels reflecting local wind influence and less regional industrialization and urbanization.

La Marmotta is one of the best-preserved Early Neolithic lakeshore settlements in the Mediterranean, yet its chronology has remained poorly defined. Previous interpretations relied mainly on decoration-based ceramic classifications and a limited radiocarbon dataset, hindering our understanding of the site’s occupational dynamics and its role in the wider European Neolithic. This study presents a revised chronological framework grounded in 35 radiocarbon determinations, including 22 new dates on short-lived botanical remains and selected wooden artifacts. The samples were carefully selected from well-documented contexts to minimise post-depositional disturbance and analyzed using Bayesian modeling. Radiocarbon results were interpreted in parallel with a detailed reassessment of ceramic artifacts and decorations. This integrated approach suggests that ceramic variability does not reflect a succession of different phases, but rather the cultural diversity of a single, dynamic community.

Burial mounds, or kurgans, are a widespread archaeological feature in ancient Eurasia. In the South Caucasus, the Kura-Araxes (KA) culture adopted these funerary structures to express horizontal social ideology through collective inhumations. KA communities also constantly re-engaged with the dead through the regular reopening of burials, contributing to a rich organic archive that relates to episodes of funerary manipulation. This article reports on the results of a radiocarbon wiggle-match obtained from a semi-burnt branch of Juniperus sp. associated with Kurgan 8 at Uzun Rama (Ganja, Azerbaijan). This structure yielded evidence of burial activity during the KA I phase (ca. 3500–3000/2900 BCE) and the post-KA, the “Early Kurgan” period (ca. 2500–2000 BCE), and the Late Bronze Age (ca. 1500–1150 BCE). The sample came from a wooden structure constructed and then burnt in the ritual closure of the kurgan by fire, marking the final stage of its KA use. The results of the wiggle-match allowed us to produce a close estimate for the felling of the branch, thus providing a refined Terminus Post Quem (TPQ) for the construction of the wooden structure itself and its use within 3204–3174 BCE. These results shed light on finer temporal resolution of burial history not just pertaining to funerary sequences, but also in terms of social engagement with visible landmarks and long-term cultural or generational memory. The results correlate with broader trends observed in other KA kurgans and settlements excavated along the Kura basin, pointing at large-scale landscape (or even historical) reconfigurations across the Kura-Araxes world.

Quantifying marine reservoir effects (MREs) across time and space is crucial for establishing accurate archaeological chronologies, including the activities of past hominines. Although the northern Iberian Peninsula shows a high density of Upper Paleolithic sites and marine shells are frequently found in these assemblages, quantification of MREs in this coastal region remains limited. We performed Bayesian modeling of radiocarbon measurements from both terrestrial (Capra pyrenaica, Cervus elaphus and other herbivores unidentified at species level) and marine (Littorina littorea Linnaeus, 1758 and Patella vulgata Linnaeus, 1758 taxa) archaeological samples recovered from the Tito Bustillo cave (Asturias, Spain) in order to determine the ΔR values for northern Iberia during the Lower Magdalenian period (ca. 20–17 ka cal BP). For the time span between 18.6 and 18.2 ka cal BP we estimated ΔR values of –298±44 14C yr and –495±122 14C yr for the periwinkle L. littorea and the common limpet P. vulgata, respectively. This finding has significant implications for future archaeological research in the northern Iberian Peninsula, as researchers must apply distinct ΔR values depending on the mollusk species selected for radiocarbon dating. Furthermore, the consistency between our calculated ΔR value for P. vulgata and previously recorded data for the same taxon from a neighboring coastal region (Cantabria, Spain) suggests remarkable stability in the marine environment of this area during the Lower Magdalenian period.

The Pelagatos volcano is situated within the Sierra Chichinautzin Volcanic Field (SCVF), 20 km southeast of Mexico City. Previous radiocarbon (14C) dating has revealed that the age of the Pelagatos volcano ranges from 2.5 ± 0.1 to 14.1 ± 0.2 ka BP (1σ). The analysis of additional cosmogenic radionuclides, such as in situ 10Be, facilitates the confirmation of the geochronology of any geological phenomenon by determining exposure ages in quartz minerals. This study proposes a new chronology for the exposure of the Pelagatos volcano rocks by in situ analysis of 10Be in olivine samples collected from five locations. The average 10Be ages in olivine from Pelagatos rocks range from 3.95 ± 0.97 ka to 5.7 ± 1.4 ka (1σ), with a mean age of 4.6 ± 0.9 ka and 4.9 ± 0.9 ka for flow 1 and flow 2, respectively. These results are consistent with previously reported 14C ages, confirming the reliability of the 10Be exposure ages obtained in this study. The in situ dating of 10Be in olivine minerals presents a viable alternative for elucidating the volcanic history and estimating the timing of the next eruption in this volcanic field.