Sixty-two 14C dates are analyzed in combination with a recently established local floating tree-ring sequence for the Early Neolithic site of La Draga (Banyoles, northeast Iberian Peninsula). Archaeological data, radiometric and dendrochronological dates, as well as sedimentary and micro-stratigraphical information are used to build a Bayesian chronological model, using the ChronoModel 2.0 and OxCal 4.4 computer programs, and IntCal 2020 calibration curve. The dendrochronological sequence is analyzed, and partially fixed to the calendrical scale using a wiggle-matching approach. Depositional events and the general stratigraphic sequence are expressed in expanded Harris Matrix diagrams and ordered in a temporal sequence using Allen Algebra. Post-depositional processes affecting the stratigraphic sequence are related both to the phreatic water level and the contemporaneous lakeshore. The most probable chronological model suggests two main Neolithic occupations, that can be divided into no less than three different “phases,” including the construction, use and repair of the foundational wooden platforms, as well as evidence for later constructions after the reorganization of the ground surface using travertine slabs. The chronological model is discussed considering both the modern debate on the Climatic oscillations during the period 8000–4800 cal BC, and the origins of the Early Neolithic in the western Mediterranean region.

Chronological and stratigraphic frameworks are of the utmost importance for Upper Paleolithic archaeology, physical anthropology, and ecology. Wide ranging radiocarbon (14C) dates were previously obtained for the Sungir burial complex in the central part of European Russia, which is well-known as the richest funeral Paleolithic assemblage in the world yet recorded. The major problem was the contamination caused by consolidants used during the recovery of human bones in the 1960s. The stratigraphy and spatial structure of the Sungir site were also not well understood previously. New radiocarbon and stable isotope data are generated for the Sungir burials. While some dates were younger due to incomplete removal of contamination, the XAD 14C age on S-1 burial (ca. 29,780 BP) was found to be statistically the same as the previously performed HYP 14C age for this burial (ca. 28,890 BP). Four animal bones found in cultural layer below the burial date to ca. 28,800–30,140 BP, suggesting that both this layer and human burials date to roughly this age range. Narrowing these ages further is difficult considering the larger errors of the 14C dates. This shows that future research attempting to 14C date material excavated many years ago needs to eliminate potential contamination from consolidants through analyses such as FTIR, prior to 14C dating. The chronology and stratigraphy of Sungir do not contradict to correlation of its lithic artifacts with the Streletskian assemblage as the East European variant of the Final Szeletian technocomplex (Early Upper Paleolithic).

Vast burial fields, some with hundreds of burials, categorize the southern Levant’s Intermediate Bronze Age period (IBA). This phenomenon contrasts with a limited number of burials found from the preceding Early Bronze III period. This paper presents the first radiocarbon dating research of sampled bones from shaft tombs from five IBA burial sites across Israel: Yehud, Jebel Qaaqir, Sheikh-Danon, Hazorea, and Kefar-Veradim. Prescreening methods, including Fourier transform infrared analysis, were applied to identify best-preserved collagen in archaeological bones for radiocarbon dating. Overall, the measured date ranges cover the IBA timeline, supporting the observation that the IBA signature shaft tombs are a fundamental tradition of the IBA culture, at least in Israel. A single IBA shaft tomb at Jebel Qaaqir which contained remains of multiple humans, supplied different dates for various people, spanning over a few hundred years. These results suggest a tribal or family-oriented IBA community with a long-lasting tradition reflected in centuries of collective burial practices.

This paper establishes the chronology of the El Pozuelo megalithic complex and discusses it in the context of other dolmens that have been dated in the southwest of the Iberian Peninsula. The working methodology combines the study of the stratigraphy and architectural sequence with the Bayesian modeling of the 27 AMS 14C dates obtained for charcoal samples from the four monuments in the Los Llanetes cluster. The most significant chronological results (at 68% probability) are (a) the antiquity and long duration of the megalithic sites, in which several monumental structures succeeded one another ca. 3970–1980 cal BC; (b) the existences of different temporalities in the Late-Final Neolithic dolmens: simple chambers (3970–3760 cal BC), elongated chambers (3790–3620 cal BC) and multiple chambers (3660–3260 cal BC; (c) the continuity of activity during the Copper Age (2980–2580 and 2530–2180 cal BC); and (d) the permanence of megalithism in the Early Bronze Age, through the presence of terraced enclosures with circular platforms ca. 2230–1940 cal BC. This diachronic sequence and the contextualized analysis of the 152 available radiocarbon dates (27 new, 125 published) supports the establishment of the temporal dynamics of megalithism in the Iberian southwest, introducing key aspects on the emergence, span, and rebuilding of the different dolmens (passage graves, simple chambers, elongated chambers, and multiple chambers) and establishing the phases of activity and reuse of the different architectural types.

Radiocarbon (14C) is the one of the most important radionuclides released from the nuclear facilities to the environment. Currently, inorganic 14C is checked during regular environmental monitoring as part of the groundwater monitoring program of the Paks Nuclear Power Plant. Several studies have shown that organic 14C can be also an important and sensitive tool for detection of possible leakage of nuclear technological systems. For this reason, a wet oxidation method was developed for the accelerator mass spectrometry (AMS) 14C measurement technique to determine the 14C activity concentration of the total dissolved carbon content of water samples, coming from environmental monitoring wells. The overall efficiency of the oxidation was around 94 ± 5% for different types of tested organic compounds. The typical 14C background (1–2 pMC) is obtained by preparation of blank samples, which allows a detection level of around 5·10–5 Bq L–1. The activity of the organic fraction can be calculated using the formula presented in the study. The method was applied for water samples deriving from environmental monitoring wells of a pressurized-water reactor (PWR) type of NPP. The results of our investigations over the 14 different water samples around the Paks NPP show that DO14C contribution to the total 14C activity concentration was between 5–25%.

Megalithic cultures of central India provide important links between the southern Neolithic-Chalcolithic cultures and the early Historical period (∼500 BC to ∼AD 700) and reveal knowledge of ancient traditions of early inhabitants. Scientific dating of these Megalithic burial sites is a challenging task due to scarcity of dateable material and alterations. Here, we present multiple accelerator mass spectrometry radiocarbon (AMS 14C) dates from equine tooth-enamel and organic food remains recovered from pots from Megalithic burials of the Vidarbha region. Using δ13CTOC and δ15N values of organic food remains recovered from pots, we deduced past-diet (palaeo-vegetation) that indicates C4 type of vegetation and thus arid climate during life-spans of these burials. We also analyzed stable δ13C and δ18O isotopes of equine tooth-enamel to investigate hydro-climatic conditions of Maharashtra (Vidarbha region). A total of 10 AMS 14C dates of tooth enamel provide a time range of AD 250–874 for two Megalithic burials. Two AMS 14C dates of organic food remains recovered from pots corroborated aforementioned time-range. The average δ13C and δ18O of equine tooth-enamel samples were −5.3 ± 2.1‰ and −2.9 ± 0.8‰, respectively, both significantly enriched compared to their modern counterparts (−13.7‰ ± 0.7 and −4.3‰ ± 1.1), indicating intense arid conditions in the past.

In many locations around the world, shell radiocarbon dates underpin archaeological research. The dating of shell brings the chronological relationship between the sample and target event (e.g., hunting and food preparation) into congruence, while shells are valuable geochemical proxies for understanding past climate dynamics and environments. However, this information can be lost as the shell, composites of biopolymers and carbonate minerals (mostly calcite and or aragonite), undergo diagenetic alteration. While studies into Pleistocene-age carbonates are common in the radiocarbon literature, there has been little research into the impact of alteration on Holocene-age shells used to interpret recent societal developments. The limits of our understanding of these diagenetic changes became evident when dating Placuna placenta (naturally calcitic) and Tegillarca granosa (naturally aragonitic) shells from the site of Thach Lac in Vietnam. These shells returned ages significantly younger than associated charcoal and terrestrial bone at the site, but standard tests for secondary recrystallization (XRD and staining techniques) did not indicate any alteration. Further investigation revealed that cryptic recrystallization (i.e., of the same crystal structure) had occurred in both the calcite and aragonite shells. This finding suggests recrystallization may have an undetected impact on some shell radiocarbon dates.

Isotopic analysis of Micropogonias furnieri otoliths were used to get insight into palaeoceanographic conditions in the Guanabara Bay and Saquarema Lagoon, Rio de Janeiro state (RJ), located on the southeastern coast of Brazil, under upwelling influence of the Cabo Frio system. Archaeological otoliths come from two Holocene shellmounds (or sambaquis): Galeão and Beirada. For the first time, radiocarbon analysis using high accuracy techniques were performed at Galeão. Age range was determined to be between 5820 and 4980 cal BP, which extends the chronology of human settlement in the Guanabara Bay. Micro-samples of the otoliths were collected sequentially from the core to the edge, to provide continuous δ18O and δ13C isotopic profiles over the lifetime of the individual fish. Derived-δ18Ooto palaeotemperature estimates vary according to seasonality, resulting in a palaeoceanographic variation between 8 to 31°C for Guanabara Bay and 8 and 28°C for the Saquarema Lagoon. Our data indicate that whitemouth croakers were captured during the Middle Holocene from the Guanabara Bay and Saguarema Lagoon and resided in cooler temperatures compared to temperatures of current conditions.

Late Holocene relative sea-level reconstructions are commonly generated using proxies preserved in salt-marsh and mangrove sediment. These depositional environments provide abundant material for radiocarbon dating in the form of identifiable macrofossils (salt marshes) and bulk organic sediment (mangroves). We explore if single-step graphitization of these samples in preparation for radiocarbon dating can increase the number and temporal resolution of relative sea-level reconstructions without a corresponding increase in cost. Dating of salt-marsh macrofossils from the northeastern United States and bulk mangrove sediment from the Federated States of Micronesia indicates that single-step graphitization generates radiocarbon ages that are indistinguishable from replicates prepared using traditional graphitization, but with a modest increase in error (mean/maximum of 6.25/15 additional 14C yr for salt-marsh macrofossils). Low 12C currents measured on bulk mangrove sediment following single-step graphitization likely render them unreliable despite their apparent accuracy. Simulated chronologies for six salt-marsh cores indicate that having twice as many radiocarbon dates (since single-step graphitization costs ∼50% of traditional graphitization) results in narrower confidence intervals for sample age estimated by age-depth models when the additional error from the single-step method is less than ∼50 14C yr (∼30 14C yr if the chronology also utilizes historical age markers). Since these thresholds are greater than our empirical estimates of the additional error, we conclude that adopting single-step graphitization for radiocarbon measurements on plant macrofossils is likely to increase precision of age-depth models by more than 20/10% (without/with historical age markers). This improvement can be implemented without additional cost.

Many waterflooding oil fields, injecting water into an oil-bearing reservoir for pressure maintenance, are in their middle to late stages of development. To explore the geological conditions and improve oilfield recovery of the most important well group of the Hu 136 block, located on the border areas of three provinces (Henan, Shandong, and Hebei), Zhongyuan Oilfield, Sinopec, central China, a 14C cross-well tracer monitoring technology was developed and applied in monitoring the development status and recognize the heterogeneity of oil reservoirs. The tracer response in the production well was tracked, and the water drive speed, swept volume of the injection fluid were obtained. Finally, the reservoir heterogeneity characteristics, such as the dilution coefficient, porosity, permeability, and average pore-throat radius, were fitted according to the mathematical model of the heterogeneous multi-layer inter-well theory. The 14C-AMS technique developed in this work is expected to be a potential analytical method for evaluating underground reservoir characteristics and providing crucial scientific guidance for the mid to late oil field recovery process.

In this study we present new carbon (δ13C) and nitrogen (δ15N) stable isotope data of human (n=13) and animal (n=40) bone and/or dentine collagen samples, alongside accelerator mass spectrometry radiocarbon (AMS 14C) dates of human remains (n=16). The studied material was sampled from Lithuanian sites dating from the Late Mesolithic to the pre-Roman Iron Age. For the first time, we present δ13C and δ15N data from Lithuanian freshwater fish as well as AMS 14C, δ13C, and δ15N measurements of human remains from six disturbed graves at the Donkalnis cemetery and from two pre-Roman Iron Age graves. According to the new results, human diet derived protein from the Late Mesolithic to Subneolithic (ca. 7000–2900 cal BC) was primarily based on freshwater fish. While previous macrobotanical and stable isotope studies has suggested that C4 plants, i.e., millet, became more widely used from the Late Bronze Age (1100–500 cal BC), our data suggests that millet consumption may have decreased during the pre-Roman Iron Age (500–1 cal BC) in the southeastern Baltic.

The dating of pollen grains is emerging as the method of choice for lacustrine climate archives that contain few datable macrofossils. Due to the need for high-purity pollen concentrates, new methods are constantly being developed to precisely separate pollen grains. Flow cytometry represents a promising alternative to conventional approaches, enabling the identification of pollen grains through fluorescence and rapid separation for radiocarbon analysis using accelerator mass spectrometry, which has so far been limited to sediments with a high proportion of conifer pollen. We present a revised method for processing large sediment samples, resulting in high-purity pollen and spore concentrates. Using this approach small- to medium-sized pollen and bryophyte spores were isolated from Lake Van sediment samples (Eastern Anatolia, Turkey) in sufficient purity for radiocarbon dating. However, a systematic age discrepancy between pollen and bryophyte spore concentrates was noted. By adapting the chemical and cytometric methods, pure pollen concentrates can be created for sediments with low organic content enabling age determination of climate archives with a low proportion of large pollen or low pollen concentration.

Estadio de Quillota (EDQ) is the largest known pre-Columbian cemetery site within the Aconcagua Valley of Central Chile. Despite its importance, existing chronological data for EDQ are limited and questions remain regarding the prehistory of the Valley, particularly around the adoption and intensification of maize agriculture, as well as the timing of Inka influence reaching the region. Seventeen new AMS radiocarbon dates presented here indicate two distinct phases of use at EDQ: An earlier phase (339–196 cal BC to cal AD 128–339), and a later phase (cal AD 1280–1387 to cal AD 1413–1458). Accompanying stable isotope (δ13C and δ15N) analyses of human bone collagen (n=22) demonstrate diachronic dietary changes corresponding to these phases, with a reliance on terrestrial C3 resources during the earlier period, followed by a heavy dependence on C4-based (maize) resources during the later use. Bayesian modeling of the dates from Late Period contexts suggests Inka influence arrived in Central Chile by ca. cal AD 1400, decades before the date cited in traditional chronologies, AD 1471. Inka expansion likely occurred here with an initial phase of interaction and exchange preceding a later phase of integration. This finding supports growing evidence that the traditional chronology of the Inka Empire requires reconsideration.

Radiocarbon (14C) dating has, since its inception, become an integral part of disciplines such as geology and archaeology, underpinning many key findings made by researchers in the past seven decades. As 14C dating develops, the need arises to revisit older findings and legacy data which may well contain laboratory errors or post-analysis misinterpretations. In this paper we examine one such finding from Sweden, namely the 1958 14C dating of the great Jordfallet (“the Earthfall”) landslide, which was published in the very first volume of Radiocarbon in 1959. We further trace how the results of this 14C dating were misunderstood in a time prior to modern radiocarbon calibration, and the impact which this mistake has had throughout academic publications, state reports and local heritage literature through the course of over sixty years. Because of this flawed interpretation the credible date of 1249 AD given to the landslide by historical sources has been overlooked. Instead, a series of dates from the mid-12th and early 13th centuries have been attributed to the landslide event based on erroneous radiocarbon analysis, a mistake which has substantial implications for the understanding of both regional and international history in medieval Scandinavia.

In this paper we present dating of archaeological samples from Croatia only performed since our last reports (Obelić et al. 2011; Horvatinčić et al. 2012). Liquid scintillation radiometric measurement technique with benzene synthesis (LSC-B) and accelerator mass spectrometry (AMS) technique were applied.