The direct carbonate procedure for accelerator mass spectrometry radiocarbon (AMS 14C) dating of submilligram samples of biogenic carbonate without graphitization is becoming widely used in a variety of studies. We compare the results of 153 paired direct carbonate and standard graphite 14C determinations on single specimens of an assortment of biogenic carbonates. A reduced major axis regression shows a strong relationship between direct carbonate and graphite percent Modern Carbon (pMC) values (m = 0.996; 95% CI [0.991–1.001]). An analysis of differences and a 95% confidence interval on pMC values reveals that there is no significant difference between direct carbonate and graphite pMC values for 76% of analyzed specimens, although variation in direct carbonate pMC is underestimated. The difference between the two methods is typically within 2 pMC, with 61% of direct carbonate pMC measurements being higher than their paired graphite counterpart. Of the 36 specimens that did yield significant differences, all but three missed the 95% significance threshold by 1.2 pMC or less. These results show that direct carbonate 14C dating of biogenic carbonates is a cost-effective and efficient complement to standard graphite 14C dating.

Dating lime mortar samples using the radiocarbon (14C) method can be difficult. This is because the contamination is similar to the primary dating material (CaCO3) and consequently difficult to remove. Mortar can also have late-in-formation pyrogenic carbonate from interactions with the environment after the initial hardening phase, such as recrystallization, fire damage or delayed hardening. When 14C dating a system of primary dating material, contamination and late-in-formation pyrogenic carbonate, one approach is multi-fraction dating with conclusiveness criteria. If a sample has sufficient contamination or late-in-formation pyrogenic carbonate, the criteria evaluate the result inconclusive. To improve inconclusive results from such samples, this study investigates sample preparation by thermal decomposition. Here samples that were inconclusively dated by the authors’ traditional method, sequential dissolution with 85% phosphoric acid, are investigated further. This study finds that CO2 thermally decomposed at low temperatures contains some late-in-formation pyrogenic carbonate. By rejecting CO2 decomposed at low temperatures, Kastelholm castle and Kimito church in Finland are conclusively and accurately dated. Furthermore, a preheating method removes some late-in-formation carbonate, but not enough for a conclusive result. Finally, thermal decomposition finds difficulty in discerning binder carbonate from limestone and marble contamination.

Calibrated radiocarbon (14C) determinations are commonly used in archaeology to assign calendar dates to a site’s chronological phases identified based on additional evidence such as stratigraphy. In the absence of such evidence, we can perform dense 14C sampling of the site to attempt to identify periods of heightened activity, separated by periods of inactivity, which correspond to archaeological phases and gaps between them. We propose a method to achieve this by hierarchical cluster analysis of the calibrated 14C dates, followed by testing of the different clustering solutions for consistency based on silhouette coefficient and statistical significance using randomization. Separate events identified in such a way can then be regarded as evidence for distinct phases of activity and used to construct a site-specific sequence. This can be in turn used as a Bayesian prior to further narrow down the distributions of the calibrated 14C dates. We assessed the validity of the method using simulated data as well as real-life archaeological data from the Bronze Age settlement of Troy. A Python implementation of the method is available online at https://github.com/demjanp/clustering_14C.

The paper presents and discusses a series of radiocarbon (14C) dates from a medieval Nubian monastery found on Kom H of Old Dongola, the capital of the kingdom of Makuria located in modern-day Sudan. The monastery was founded in the 6th–7th century AD and although it probably ceased to function in the 14th century, the site remained occupied until the beginning of the 15th century. The investigated courtyard of the monastery was in use from the 11th to the 14th century, as indicated by the ceramics and 14C analysis results presented here. The dates under consideration are the first published series of 14C dates from this site, which is of crucial importance for historical research on medieval Nubian Christianity and monasticism. They permit to begin building an absolute chronological framework for research on the archaeological finds from the site and region. A group of finds in particular need of such a framework are ceramics, and the implications of the 14C dates for pottery assemblages found in the dated contexts are discussed. The conclusions summarize the significance of the datings for the history of the site.

Triliths are megalithic monuments scattered across the coastal plains of southern and southeastern Arabia. They consist of aligned standing stones with a parallel row of large hearths and form a space, the meaning of which is undoubtedly significant but nonetheless still unknown. This paper presents a new radiocarbon (14C) dataset acquired during the two field seasons 2018–2019 of the TSMO (Trilith Stone Monuments of Oman) project which investigated the spatial and temporal patterns of the triliths. The excavation and sampling of trilith hearths across Oman yielded a dataset of 30 new 14C dates, extending the use of trilith monuments to as early as the Iron Age III period (600–300 BC). The earlier dates are linked to two-phase trilith sites in south-central Oman. The three 14C pairs collected from the two-phase trilith sites indicated gaps between the trilith construction phases from 35 to 475 years (2 σ). The preliminary spatio-temporal analysis shows the geographical expansion of populations using trilith monuments during the 5th to 1st century BC and a later pull back in the 1st and 2nd century AD. The new 14C dataset for trilith sites will help towards a better understanding of Iron Age communities in southeastern Arabia.

The article reports on a new sampling method and the archaeological context of cave drawings, which include the oldest currently known graffiti in the Czech Republic. Between 2016 and 2020, samples with a small amount of charcoal were taken from drawings found in Kateřinská Cave (Catherine’s Cave) of the Moravian Karst in the Czech Republic. A new gentle method of sampling charcoal from the cave walls was developed for the purpose of radiocarbon (14C) dating cave drawings of unknown age, while preserving the contours of the drawings. 14C analysis has provided data from four periods of prehistory and history: from the Neolithic around 5000 BC, the turn of the Neolithic and Eneolithic around 4300 BC, the Hallstatt Period from 800–450 BC, and also from the Middle Ages (13th century). The radiocarbon dates of the graffiti correspond to the dates of the pottery finds from the entrance portal of Kateřinská Cave, thus validating the dates and the sampling method.

This study obtained calendar dates by radiocarbon accelerator mass spectrometry (14C AMS) dating sequential tree-rings of wooden support posts from the buried remains of traditional Kitkahahki Pawnee earthlodges preserved at an archaeological site on the Central Great Plains, USA. The tree-ring segments from the site were dendrochronologically analyzed prior to this study, but the cross-matched site chronology could not be definitively cross-dated and was thus “floating” in time. Our study represents the first floating tree-ring chronology from the Great Plains to be anchored in time by means of independent radiocarbon analysis. Three specimens were analyzed and dated to 1724–1774 CE (82.0% probability), 1774–1794 CE (95.4% probability), and 1800–1820 CE (95.4% probability). These dates correspond to the hypothetical timing of Kitkahahki ethnogensis, the main phase of village growth in the area, and a later reoccupation during a turbulent period in regional history. The results of this study conform to a scenario in which chaotic social conditions correspond to an increase in residential mobility between the core of Pawnee territory and a southern frontier in the Republican River valley.

A coupled accelerator mass spectrometer–gas interface system has been successfully operating at the Hertelendi Laboratory of Environmental Studies, Debrecen, Hungary, since 2013. Over the last 6 years more than 500 gas targets were measured below 100 µg carbon content for carbon isotopic composition. The system was tested with blanks, OxII, IAEA-C1, IAEA-C2, and IAEA-C7 standards. The performance of our instrumentation shows good agreement with other published gas-interface system data and also shows a quite good agreement with the nominal value of international standard samples. There is a measurable but quite small memory effect after modern samples, but this does not significantly affect the final results. Typical ion currents at the low energy side were between 10–15 µA with a 5% CO2 in He mixing ratio. The relative errors average ±6% for samples greater than or equal to 10 µgC sample with mean count rates of 300 counts per microgram C for OxII. The blank is comparable with other systems, which is 0.0050 ± 0.0018 F14C or 34,000–47,000 yr BP, which allows for the routine measurement of both of small environmental and archeological samples.

The Old Copper Complex (OCC) refers to the production of heavy copper-tool technology by Archaic Native American societies in the Lake Superior region. To better define the timing of the OCC, we evaluated 53 (eight new and 45 published) radiocarbon (14C) dates associated with copper artifacts and mines. We compared these dates to six lake sediment-based chronologies of copper mining and annealing in the Michigan Copper District. 14C dates grouped by archaeological context show that cremation remains, and wood and cordage embedded in copper artifacts have ages that overlap with the timing of high lead (Pb) concentrations in lake sediment. In contrast, dates in stratigraphic association and from mines are younger than those from embedded and cremation materials, suggesting that the former groups reflect the timing of processes that occurred post-abandonment. The comparatively young dates obtained from copper mines therefore likely reflect abandonment and infill of the mines rather than active use. Excluding three anomalously young samples, the ages of embedded organic material associated with 15 OCC copper artifacts range from 8500 to 3580 cal BP, confirming that the OCC is among the oldest known metalworking societies in the world.

The application of accelerator mass spectrometry radiocarbon (AMS 14C) dating in forensics is made possible by the use of the large excursion of the 14C concentration in the post-WWII terrestrial atmosphere due to nuclear testing as a reference curve for data calibration. By this approach high-precision analyses are possible on samples younger than ∼70 years. Nevertheless, the routine, widespread application of the method in the practice of forensics still appears to be limited by different issues due to possible complex interpretation of the results. We present the results of an intercomparison exercise carried out in the framework of an International Atomic Energy Agency (IAEA) CRP-Coordinated Research Project between three AMS laboratories in Italy, Hungary, and Switzerland. Bone and ivory samples were selected with ages spanning from background (>50 ka) to 2018. The results obtained allow us to assess the high degree of reproducibility of the results and the remarkable consistency of the experimental determinations.

Very little is known about the manufacturing and use of ancient Egyptian instruments, and their discovery is very rare. An extensive radiocarbon (14C) dating program has been conducted on 25 ancient Egyptian musical instruments currently held at the Louvre Museum (musée du Louvre) and the Lyon Museum of Fine Arts (musée des Beaux-Arts de Lyon). This study includes cordophones (harps, lyres, lutes), membranophones (drums, tambourines), idiophones (clappers, crotales), as well as wind instruments (oboe) that have entered the museum collections during the 19th century or the first half of the 20th century; consequently, the original archaeological contexts of their discoveries are poorly understood. Approximately 50 14C dates enable drawing a general overview of the instruments manufacturing. A wide variety of wood material has been identified, representing both indigenous species and imported species. Results indicate that the native flora of Egypt was exclusively used until the Third Intermediate Period when the first imports could be identified. 14C results are not always consistent with relative dates previously thought, mainly based on stylistic criteria. They demonstrate these collections hold very well-preserved objects extending over 2500 years, from the Second Intermediate Period (ca. 1700 BCE) to the start of the Islamic Period (8th century CE). This project provides important results for the knowledge of ancient Egyptian musical instrument crafts.

We report a new series of radiocarbon (14C) dates on the MIS 3 megafauna for a previously poorly studied region of southeastern West Siberia. Some species, like woolly mammoth and woolly rhinoceros, and Pleistocene bison and horse, existed throughout the MIS 3 (ca. 29–59 ka cal BP); cave hyaena is dated to ca. 46,400 cal BP. The very late 14C dates on Khozarian steppe elephant (Mammuthus trogontherii chosaricus), ca. 45,100–45,400 cal BP, may indicate the survival of this species in Siberia up to MIS 3. More work is needed to confirm or reject this suggestion. Previously, Khozarian steppe elephant was known in Siberia only at the beginning of the Late Pleistocene (MIS 5e).

The main goal of our research project was to date the Early and Middle Copper Age (4500/4450–3800 cal BC) of the Great Hungarian Plain more precisely. In our project, we took samples for accelerator mass spectrometry (AMS) dating from both settlement features and burials, and the data were analyzed using Bayesian modeling. We examined the Early and Middle Copper Age finds of the Great Hungarian Plain on several levels (site, microregional, and regional levels) using a bottom-up approach. The AMS measurements were supplemented by statistics-based pottery analysis in order to make our understanding of the relationship between the Tiszapolgár and Bodrogkeresztúr cultures more detailed. As a result, we can see a significant, 130 (68.2%) 230 years overlap between the two types of find assemblages, which contradicts to the earlier accepted chronological sequences created by the traditional culture-historical approach. According to the stylistic analyzes, the two ceramic styles are not clearly distinguishable.

When European colonists arrived in the late 19th century, large villages dotted the coastline of the Gulf of Papua (southern Papua New Guinea). These central places sustained long-distance exchange and decade-spanning ceremonial cycles. Besides ethnohistoric records, little is known of the villages’ antiquity, spatiality, or development. Here we combine oral traditional and 14C chronological evidence to investigate the spatial history of two ancestral village sites in Orokolo Bay: Popo and Mirimua Mapoe. A Bayesian model composed of 35 14C assays from seven excavations, alongside the oral traditional accounts, demonstrates that people lived at Popo from 765–575 cal BP until 220–40 cal BP, at which time they moved southwards to Mirimua Mapoe. The village of Popo spanned ca. 34 ha and was composed of various estates, each occupied by a different tribe. Through time, the inhabitants of Popo transformed (e.g., expanded, contracted, and shifted) the village to manage social and ceremonial priorities, long-distance exchange opportunities and changing marine environments. Ours is a crucial case study of how oral traditional ways of understanding the past interrelate with the information generated by Bayesian 14C analyses. We conclude by reflecting on the limitations, strengths, and uncertainties inherent to these forms of chronological knowledge.

This article discusses the absolute chronology of collective burials of the Trzciniec Cultural Circle communities of the Middle Bronze Age in East Central Europe. Based on Bayesian modeling of 91 accelerator mass spectrometry radiocarbon (AMS 14C) dates from 18 cemeteries, the practice of collective burying of individuals was linked to a period of 400–640 (95.4%) years, between 1830–1690 (95.4%) and 1320–1160 (95.4%) BC. Collective burials in mounds with both cremation and inhumation rites were found earliest in the upland zone regardless of grave structure type (mounded or flat). Bayesian modeling of 14C determinations suggests that this practice was being transmitted generally from the southeast to the northwest direction. Bayesian modeling of the dates from the largest cemetery in Żerniki Górne, Lesser Poland Upland, confirmed the duration of use of the necropolis as ca. 140–310 (95.4%) years. Further results show the partial contemporaneity of burials and allow formulation of a spatial and temporal development model of the necropolis. Based on the investigation, some graves were used over just a couple of years and others over nearly 200, with up to 30 individuals found in a single grave.

Over the past few decades, several excavations that have been performed in the Fars Neolithic sites have resulted in the presentation of different chronologies for the region. Most of the research in Fars centered on the Kur River Basin (KRB). Fars has always had a different environment for the formation of different cultures over time, therefore, in order to reach a better understanding of the prehistoric cultures of the region it is necessary to make a brief review of the geographical zones of the plains and valleys of Fars province. Taking into account the existence of several questions and ambiguities regarding Neolithic Fars, the Hormangan site, located in the Bavant River Basin, was excavated. During the excavation, two settlement phases were identified that contained cultural materials relatively comparable to Tol-e Mushki, Tol-e Jari B, Kushk Hezar, and Rahmat Abad sequences. The goal of this paper is to explore the absolute chronology of the Hormangan site as well as other Neolithic sites located in the northern half of the Fars region with a special reference to the local cultural and technological sides of different Neolithic sites throughout the region. Bearing in mind the similarities of Bashi materials with Hormangan, Rahmat Abad, and Mushki regions and the absolute chronology of these regions, consideration of Bashi phase does not seem logical. Therefore, by comparing the cultural materials and absolute chronology done in other regions, a sequence chronology including Rahmat Abad (7500–7000 BC), formative Mushki (7000–6400 BC), Mushki (6400–6000 BC), Jari (6000–5600 BC), and Shams Abad (5600–5200 BC) for the Neolithic period of Fars can be presented. According to the excavation of Rahmatabad and Tal-e Sangi, it seems that Fars was inhabited in the middle of the 8th millennium BC and the Neolithic package entered this area, and there is no evidence of the Neolithization process. In the past, the Mushaki period was introduced as the oldest pottery Neolithic period, but with new excavations, it seems that the use of pottery had become common in Fars, as in many parts of Southwest Asia, around 7000 BC.

We determined the chemical composition of pine needles to monitor environmental contamination in an urban forest environment in the most industrialized part of southern Poland. The concentrations of radiocarbon (14C), trace elements (Cr, Co, Ni, Cu, Zn, Rb, Sr, Ba, Ce, Pb) and the Pb isotope composition were measured in needles from Pinus sylvestris L. growing in nine urban forests near five factories. The investigated young pine needles were collected in January 2013 and September 2013, respectively. 14C concentration was determined by liquid scintillation counter, trace elemental concentration and Pb isotope ratio were determined by ICP-MS and MC-ICP-MS, respectively. Analysis of trace metal pollution is based on the assumption that element concentrations in tree foliage represent element availability in the environment. Different space-time patterns of element accumulation in pine needles were observed. The variation in isotopic composition reflects a mix between different anthropogenic sources.

The excavation of a building in the village of Felanitx in the eastern part of the island of Mallorca (Balearic Islands) has revealed the existence of a small necropolis. The inhumations did not provide grave goods except for a bronze belt buckle for which the typological study suggests a Late Antique chronology. The stratigraphical sequence however seems to suggest a possible evolution of the space across time since some graves are cut by others. In order to obtain an absolute date for the necropolis and to verify if there are chronological differences between the graves, a total of 6 human bones samples have been 14C dated by AMS. The results of the radiocarbon dating confirm a Late Antique chronology (4th to 7th century AD) for the graves but do not suggest a chronological evolution. Despite the fact that the knowledge of the necropolis is still fragmentary, the results are extremely important because they provide an absolute date for a Late Antique necropolis in the Mallorcan rural area.