This paper presents results of accelerator mass spectrometry radiocarbon (AMS 14C) dating of prehistoric samples (human and animal bones, cremated human bones, charcoals, and other charred plant macroremains) from archaeological sites located in the area of Dobużek Scarp, on the Sokal Ridge in central-eastern Poland (E Poland). The date list reports 46 14C age measurements performed within the project “The Dobużek Scarp Microregion as a part of a physiological and biocultural frontier between the Baltic and the Pontic zone (from the 6th to the 2nd millennium BC)” conducted in 2016–2021. The resulting 14C dates fall into quite a long interval, which in terms of the regional archaeological periodization lasts from the Middle Eneolithic to the Early Iron Age, and in terms of the climatological one corresponds with the Subboreal.

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.

The article presents the results of the absolute dating of 31 pre-Columbian funerary bundles excavated on the Cerro Colorado site located in the northern part of the Peruvian Central Coast, where the Chancay culture developed in the last centuries before the Spanish invasion. The typical custom in this region was to wrap the dead with textiles and a vegetal material, by which the bundle was created. The funerary bundles of the Cerro Colorado differed in terms of the complexity, quantity and quality of the materials used (especially textiles and metal ornament). Before our project, there was not a single radiocarbon (14C) date for an undisturbed Chancay tomb, which made it impossible to understand the temporal dependency between the elaborated, standard, and modest bundles. Our results finally shed light on their proper chronological position, also demonstrating that the most elaborate bundles were created between the 13th and 15th centuries.

The Middle Upper Palaeolithic (MUP) in eastern Central Europe (ECE) comprises three variants of Gravettian culture: Early Gravettian, Pavlovian, and Late Gravettian. While Early Gravettian and Pavlovian are merely located in Lower Austria and Moravia, the Late Gravettian occupations occurred over the entire territory of ECE. Compared to the number of sites the radiocarbon dating and the absolute chronology of the Late Gravettian is rather poor. The results presented here bring a new set of radiocarbon (14C) dates for the Late Gravettian period in ECE and propose that this period began and ended earlier than previously suggested.

The paper presents radiocarbon (14C) dates of samples collected from the Bronze Age cultural strata (VI–II) excavated within Sector P, Tell Arbid, Khabur Triangle, northern Mesopotamia. These strata contain objects (remains of a caravanserai, pits, graves, pottery kilns, and multi-phase houses) representing the periods of Early Jezirah 4-5, and Old Jezirah I-II. 14C dating of these strata was especially important because of a clearly visible period of abandonment of the area at the onset of 2nd millennium BC, recorded on all Khabur Triangle sites studied so far, and because of the questionable reliability of the chronology derived from scarce historical sources. Of the 29 samples of cereal grains, 9 appeared to contain residual material, while Bayesian-analyzed 14C ages of the remaining 20 allowed us to say that, at the turn of the 3rd millennium BC, Tell Arbid was abandoned later than other sites in the area, and that it was occupied over a distinctly longer period during the early 2nd millennium.

Our project aimed to construct a Scots Pine (Pinus sylvestris L.) chronology for part of the Late Glacial and reconstruct changes in the 14C concentrations during this period. Kwiatków (Kolska Basin, central Poland) proved to be very prospective site, in which wood from the end of Allerød was recognized. A level of organic deposits with so-called fossil forest was encountered within the late-Vistulian terrace of the low valley of the Warta river. Dendrochronological analysis of over 267 samples complying to the requirements of the method allowed, at the present stage of the research, to construct a chronology spanning 265 yr. Fifty-two samples (5 consecutive rings each) were subjected to α-cellulose extraction and 14C measurements. Ninety-six results and the wiggle-matching technique anchor the chronology to the period 13,821–13,561 cal BP (Acomb=141.6%) according to the D_Sequence procedure and the IntCal13 calibration curve or to 13,800–13,540 cal BP according to the wiggle-matching technique using the χ2 test and raw data, i.e. the Heidelberg tree-ring sequence.

An accurate radiocarbon (14C) dating of mortars requires adjusting the sample preparation procedure to each specific mortar composition. In order to follow the influence of mortar components and the preparation procedure on dating results, a mortar intercomparison study (MODIS) was undertaken by 10 organizations (institutes and laboratories) in the analyses of four different types of mortars (see in this issue Hajdas et al. 2017 and Hayen et al. 2017). This paper presents the preparation protocol DoM v.1 applied by the Poznań team, together with dating results on a set of mortar samples used for the of intercomparison. This procedure involved petrographic observations, SEM-EDS analyses, different mechanical-chemical preparation, a test of leaching reaction for available fractions, and finally 14C dating of chosen samples. The applied preparation allows one to obtain dry-sieved grain fractions and different fractions from suspension: grain fractions from suspension collected in different times of leaching, repeated suspension (different portions), as well as suspension collected at different times of sedimentation. The obtained results show the great importance of good sampling and the influence of sample preparation on 14C dating results.

Absolute dating of mortars is crucial when trying to pin down construction phases of archaeological sites and historic stone buildings to a certain point in time or to confirm, but possibly also challenge, existing chronologies. To evaluate various sample preparation methods for radiocarbon (14C) dating of mortars as well as to compare different dating methods, i.e. 14C and optically stimulated luminescence (OSL), a mortar dating intercomparison study (MODIS) was set up, exploring existing limits and needs for further research. Four mortar samples were selected and distributed among the participating laboratories: one of which was expected not to present any problem related to the sample preparation methodologies for anthropogenic lime extraction, whereas all others addressed specific known sample preparation issues. Data obtained from the various mortar dating approaches are evaluated relative to the historical framework of the mortar samples and any deviation observed is contextualized to the composition and specific mineralogy of the sampled material.

Seven radiocarbon laboratories: Åbo/Aarhus, CIRCE, CIRCe, ETHZ, Poznań, RICH, and Milano-Bicocca performed separation of carbonaceous fractions suitable for 14C dating of four mortar samples selected for the MOrtar Dating Inter-comparison Study (MODIS). In addition, optically stimulated luminescence (OSL) analyses were completed by Milano-Bicocca and IRAMAT-CRP2A Bordeaux. Each laboratory performed separation according to laboratory protocol. Results of this first intercomparison show that even though consistent 14C ages were obtained by different laboratories, two mortars yielded ages different than expected from the archaeological context.

A megaslump at Batagaika, in northern Yakutia, exposes a remarkable stratigraphic sequence of permafrost deposits ~50–80 m thick. To determine their potential for answering key questions about Quaternary environmental and climatic change in northeast Siberia, we carried out a reconnaissance study of their cryostratigraphy and paleoecology, supported by four rangefinder 14C ages. The sequence includes two ice complexes separated by a unit of fine sand containing narrow syngenetic ice wedges and multiple paleosols. Overall, the sequence developed as permafrost grew syngenetically through an eolian sand sheet aggrading on a hillslope. Wood remains occur in two forest beds, each associated with a reddened weathering horizon. The lower bed contains high amounts of Larix pollen (>20%), plus small amounts of Picea and Pinus pumila, and is attributed to interglacial conditions. Pollen from the overlying sequence is dominated by herbaceous taxa (~70%–80%) attributed to an open tundra landscape during interstadial climatic conditions. Of three hypothetical age schemes considered, we tentatively attribute much of the Batagaika sequence to Marine Oxygen Isotope Stage (MIS) 3. The upper and lower forest beds may represent a mid–MIS 3 optimum and MIS 5, respectively, although we cannot discount alternative attributions to MIS 5 and 7.

There is an ongoing controversial discussion as to whether n-alkane lipid biomarkers—and organic matter of loess in general—reflect a synsedimentary paleoenvironmental/climate signal or whether they are significantly affected by postdepositional “contamination,” for example related to root and rhizomicrobial activity. In order to address this issue at our study site (the Middle to Late Weichselian loess-paleosol sequence Gleina in Saxony, Germany), we determined and compared radiocarbon ages of bulk n-alkanes and sedimentation ages, as assessed by optically stimulated luminescence (OSL) dating. The bulk n-alkanes of the four dated samples yielded calibrated 14C ages ranging from 24.1 to 49.7 cal ka BP (95.4% probability ranges). While the three uppermost n-alkane samples are well within the range or even slightly older than the OSL-inferred sedimentation ages, the lowermost n-alkane sample is slightly younger than the OSL ages. There is hence little or no evidence at our study site for n-alkanes in loess-paleosol sequences being significantly “contaminated” by deep subsoil rooting or microbial processes. We propose a 14C isotope mass balance calculation for estimating such contaminations quantitatively. Radiocarbon dating of bulk n-alkanes might have great potential for Quaternary research, and we encourage further comparative 14C and OSL studies.

Despite their great potential, charred particles of chaff-and-straw temper from daub architecture have very rarely been considered as material suitable for 14C dating. This short paper is intended to change this situation. With this aim in mind, we first present the rationale and objectives of the sampling procedure based on archaeobotanical exploration of prehistoric remains of daub architecture, and then report and discuss the results of a short chronometric exercise based on such samples. The empirical verification of the sampling procedure was based on finds related to the epi-Lengyel culture from Upper Silesia.

The repetitive and highly structured domestic architecture of Çatalhöyük is a distinctive feature of this important Neolithic settlement. At the very end of the sequence, however, excavations on the surface of the East Mound reveal changes in household construction and burial chambers. Bayesian analysis of 56 AMS radiocarbon dates from these layers allow the date and pace of these changes to be established in detail. Settlement activity on the East Mound ceased just after 6000 cal BC, and was followed by the cessation of Neolithic burial activity a few decades later.

Reconstructions arc presented of past growth rates of 10 Acacia tortilis trees, 5 growing at an arid site (Gebeit, Sudan) and 5 at a hyperarid site (Wadi Nuqrus, Egypt). The reconstructions were made using a free-shape age-depth model based on a series of 14C dates obtained on samples taken along the wood cores retrieved from the trunks of the trees (78 dates in total). In spite of the large difference in annual precipitation between the 2 sites, the range of ages of the trees (60–350 yr) and the variability in their growth rates are quite similar across both sites, whereas within-site growth rates are quite different even for closely spaced individuals. However, the pattern of growth rates of Acacias from the hyperarid Wadi Nuqrus indicates 2 periods of different aridity (the less arid AD 1650–1780 and more arid AD 1780–1930), while at Gebeit no such pattern has been detected.

Mortar as a mixture of binder and aggregate can be reliably dated with radiocarbon if the applied preparation method allows one to eliminate unburnt carbonate fragments, bearing 14C-depleted carbon and causing overestimation of 14C age. To avoid these problems, separation of specific grain-size fractions of mortar and 14C analysis of the CO2 portions collected in different time intervals of the acid-leaching reaction is usually helpful. In the present paper, we demonstrate that the rate of the leaching reaction of mortars with dense carbonate aggregate differs from that of mortars with crumbled limestone and scattered shells (e.g. of foraminifera). Verification of the obtained 14C dates against historical sources shows that for mortars rich in foraminiferous limestone, a reaction rate-based chemical elimination of “dead carbon” may appear impossible.

Archaeological excavations performed for many years in Łekno, central Poland, have exposed relicts of wooden fortified settlements, and in its enclosure also basements of stone buildings, consisting of Romanesque rotunda and a Cistercian monastery, including an oratory, church, and abbot's house. Earlier archaeological, structural, and stratigraphical studies have shown that these buildings were constructed in a sequence and represented several phases of development.

In this paper, we present results of radiocarbon dating of stone buildings of the rotunda and the monastery. For 14C dating, we used tiny pieces of charcoal retrieved from calcareous and gypsum mortar binding stone elements from the buildings. These pieces were incorporated in mortar during the firing process, where the fuel used for firing was wood. Most of the obtained 14C dates formed clear groups, confirming that individual buildings were constructed in separate periods. Calibrated 14C dates of these phases agree well with the constraints provided by historical sources, and enable us to set their ages with accuracy better than previously available. In particular, we have learned that the oldest rotunda was built at the boundary of the 10/11th centuries, and the church and the abbot's house, before AD 1250. However, some samples gave much too old 14C ages, clearly reflecting the use of old wood for firing. These problems were revealed only for samples from the rotunda and for the gypsum stone ornamental details.

The presented research involves the analysis and radiocarbon dating of 2 different groups of carbonate mortars, from Kraków, Poland and Hippos, Israel. Differences in composition of the mortars are reflected in different rates of their acid leaching. The Israeli mortars contain carbonate-basaltic aggregates, which may cause overestimation of 14C age. Preliminary processing of these samples (choice of selected grain-size fraction and collection of CO2 released during the first phase of the acid-leaching reaction), enabled us to obtain good agreement between the 14C dates and the age derived from historical contexts. A similar method of preliminary processing was applied to the carbonate mortars of the Medieval building in Kraków. The Polish samples represent carbonate mortars with some admixture of quartz aggregates, suggesting that they would be an ideal material for 14C dating. However, these samples contained white lumps of carbonates, the structure of which differed from that of the binder. These admixtures, possibly related to the hydrological conditions at the site and to the character of the ingredients, appeared modern, and if not removed prior to acid leaching, they could cause underestimation of the age of samples. The 14C dates of the mortars from the walls of the Small Scales building in Kraków are the first obtained for this object, and their sequence does not contradict archaeological indications on several phases of the building construction.

We present the first results of an accelerator mass spectrometry (AMS) radiocarbon intercomparison program on 3 different charcoal samples collected in one of the hearths of the Megaceros gallery of Chauvet Cave (Ardèche, France). This cave, rich in parietal decoration, is important for the study of the appearance and evolution of prehistoric art because certain drawings have been 14C dated to the Aurignacian period at the beginning of the Upper Paleolithic. The new dates indicate an age of about 32,000 BP, which is consistent with this attribution and in agreement with the results from the same sector of the cave measured previously at the Laboratoire des Sciences du Climat et de l'Environnement (LSCE). Six laboratories were involved in the intercomparison. Samples were measured in 4 AMS facilities: Center for Isotope Research, Groningen University, the Netherlands; the Oxford Radiocarbon Accelerator Unit, UK; the Centre de datation par le carbone 14, Univ. Claude Bernard Lyon 1, France (measured by AMS facilities of Poznań University, Poland); and the LSCE, UMR CEA-CNRS-UVSQ, France (measured by the Leibniz-Labor of Christian-Albrechts-Universität Kiel, Germany).

We present studies of 9 modern (up to 400-yr-old) peat sections from Slovenia, Switzerland, Austria, Italy, and Finland. Precise radiocarbon dating of modern samples is possible due to the large bomb peak of atmospheric 14C concentration in 1963 and the following rapid decline in the 14C level. All the analyzed 14C profiles appeared concordant with the shape of the bomb peak of atmospheric 14C concentration, integrated over some time interval with a length specific to the peat section. In the peat layers covered by the bomb peak, calendar ages of individual peat samples could be determined almost immediately, with an accuracy of 2–3 yr. In the pre-bomb sections, the calendar ages of individual dated samples are determined in the form of multi-modal probability distributions of about 300 yr wide (about AD 1650–1950). However, simultaneous use of the post-bomb and pre-bomb 14C dates, and lithological information, enabled the rejection of most modes of probability distributions in the pre-bomb section. In effect, precise age-depth models of the post-bomb sections have been extended back in time, into the “wiggly” part of the 14C calibration curve.

Our study has demonstrated that where annual resolution is concerned, tissues of Sphagnum are the only representative material for 14C dating, although even samples of pure Sphagnum collected from a very thin slice of the peat section contain tissues grown in different years, so they integrate the atmospheric 14C signal over a period of time. This time period (0.5–8 yr, depending on the site) seems to correlate with the peat accumulation rate, but it also depends on how the sampled peat sections were handled. When constructing age-depth models, for some peat sections we used the strategy of multi-stage 14C dating. This led to a drastic reduction in the uncertainty of the age-depth models, by dating only a few additional samples in the profile.

Our study is the first in which peat sections from the late pre-bomb time (AD 1900–1960) have been precisely dated at a high temporal resolution. In this time interval, 14C ages of all the samples dated were younger than those derived from the atmospheric calibration curve, apparently due to the effect of integration. Evidently, the determination of calendar ages based on 14C dating of single peat samples from that interval may be affected by a serious error if the possibility of integration is ignored.

Accelerator mass spectrometry radiocarbon (AMS 14C) dating of the late glacial section of laminated sediments from Lake Gościąż and Lake Perespilno, Poland, performed with time resolution of 20–30 years suggests quasi-periodic oscillations of δ14C. The regularity of oscillations has been checked by the Maximum Entropy and Fast Fourier Transform methods (MEM and FFT), which revealed peaks at 200 and 230 yr. These periods are similar to those found in the high-precision Holocene δ14C record, and attributed to the changing sun. The analytical assessment of the significance of the FFT and MEM peaks is problematic because of non-uniform spacing and various uncertainties in the input data. The significance of the peaks has therefore been studied by the Monte-Carlo method. Because the original data were approximated with a spline function, the amplitude of the MEM and FFT peaks depends on the stiffness of the spline, which is strongly related to the “real” uncertainty of 14C ages. The Monte-Carlo experiments demonstrate that the significance levels of the MEM and FFT peaks also depend on the spline stiffness. Therefore, the existence of solar 14C variations in the Late Glacial remains an open question.