This study used high-precision radiocarbon bomb-pulse dating of selected wood rings to provide an independent validation of the tree growth periodicity of Pseudolmedia rigida (Klotzsch & H. Karst) Cuatrec. from the Moraceae family, collected in the Madidi National Park in Bolivia. 14C content was measured by accelerator mass spectrometry (AMS) in 10 samples from a single tree covering over 70 yr from 1939 to 2011. These preliminary calendar dates were determined by dendrochronological techniques and were also used to select the samples for 14C AMS. In order to validate these preliminary dates using the established Southern Hemisphere (SH) 14C atmospheric concentration data set, the targeted rings were selected to be formed during periods before and after the 14C bomb spike nuclear tests (i.e. 1950s–1960s). The excellent agreement of the dendrochronological dates and the 14C signatures in tree rings associated with the same dates provided by the bomb-pulse 14C atmospheric values for the SH (SHCal zone 1–2) confirms the annual periodicity of the observed growth layers, and thus the high potential of this species for tree-ring analysis. The lack of discrepancies between both data sets also suggests that there are no significant latitudinal differences between the 14C SHCal zone 1–2 curve and the 14C values obtained from the selected tree rings at this geographic location (14°33′S, 68°49′W) in South America. The annual resolution of P. rigida tree rings opens the possibility of broader applications of dendrochronological analysis for ecological and paleoclimatic studies in the Bolivian tropics, as well as the possibility of using wood samples from some tree species from this region to improve the quality of the bomb-pulse 14C SHCal curve at this latitude.

The Cardamom Mountain Jar and Coffin burial site of Phnom Khnang Peung is the most extensive example of the distinctive burial ritual first reported by Beavan et al. (2012a). The 40 intact Mae Nam Noi and late Angkorian-era ceramic jars used as burial vessels held a total of up to 152 individuals, representing the largest corpus of skeletal remains of any of the 10 known Jar and Coffin burial sites that have been discovered in the eastern ranges of the Cardamom Mountains of Cambodia. We report here on the radiocarbon dating of this site and notable burial phenomena, using a Bayesian approach to model the start and end date of activity as well as its overall span. The results of the dating and Bayesian analyses indicate that the Phnom Khnang Peung site's earliest burials began cal AD 1420–1440 (95% probability). Interestingly, the concentration of burial activity spans only 15–45 years (95% probability), despite the large number of inhumations at the site. The 14C chronology presented for the site places the Highland burial ritual coincident with a period of economic, political, and societal transformations in the lowland Angkorian polity, but the unique burial practice and trade relationships evidenced by the burial goods and maritime trade ware ceramics employed in the burial ritual suggest these Highland people were a culture apart from Angkorian cultural influences.

Archaeological investigations in the Iron Gates reach of the Lower Danube Valley between 1964 and 1984 revealed an important concentration of Stone Age sites, which together provide the most detailed record of Mesolithic and Early Neolithic settlement from any area of southeastern Europe. Over 425 human burials were excavated from 15 sites. Of these, less than one-fifth have been directly dated. This article presents 37 new AMS dates on human bone from five sites in the Iron Gates, together with the corresponding δ13C and δ15N values. They include the first dates on human bone from two sites, Icoana and Velesnica. The results are important for the chronology of Stone Age mortuary practices in the Iron Gates and the timing of the Mesolithic–Neolithic transition in the region.

The thousands of Bronze Age burial mounds of northwestern Europe often have complex histories, with multiple construction phases and secondary burials added to these mounds. It can be difficult to understand the dynamic nature of these events and the ebb and flow of activities in these monumental funerary landscapes. This article presents chronological models of five Bronze Age barrows from two sites. A total of 41 radiocarbon-dated cremation burials were fitted into several chronological sequences. The results from the chronological models at both sites suggest that the creation of a burial mound was just one event within a much longer funerary history. For both sites, there are indications that the deceased were buried in flat graves decades and sometimes more than a century prior to any monument construction. Once in place, the barrows were then used as a repository for the dead for decades afterwards. At the same time, a comparison of the models suggests that funerary events at both sites were punctuated. At one site, several barrows were in use simultaneously, at the other, barrows seem to be each other's successor. The models provide evidence for both protracted histories as well as punctuated events.

One century after its discovery, the Columns Tomb of Kumbi Saleh (Mauritania) remains an archaeological riddle. Since 1914, six field programs have been successively carried out at the medieval urban site of Kumbi Saleh, which now is commonly identified as Ghana. The latter was the famous capital city of the medieval West African state, which controlled the gold mines of West Africa and was involved in the gold trade with North Africa and the Mediterranean Basin. However, interpretation of the tomb, the largest structure from the necropolis, is still an issue as its dating itself has never been firmly established. As a consequence, scholars have usually referred to an unsatisfactory timeframe spanning 1000 years. The study of this monument was recently resumed, motivated by the rediscovery of bones collected in the tomb in 1914 and stored at the Musée de 1'Homme (Paris, France). AMS radiocarbon dating of the bone and tooth apatite fraction of three skulls demonstrates that the three individuals occupying the main vault of the tomb died between the end of the 11th century and the 12th century, precisely at the time of expansion of the Muslim Almoravid movement south of Sahara.

The Late Bronze Age to the Iron Age transition involves profound cultural and political changes in the southern Levant. The transition is dated to the 12th century BC, based on archaeological artifacts and historical documents. A more precise absolute date for this transition for the southern Levant based on radiocarbon is difficult since the 14C calibration curve reduces precision significantly due to wiggles that form an approximately 200-yr-long plateau. This article analyzes 14C samples from the Late Bronze Age to the Iron Age transition at Qubur el-Walaydah. To increase the resolution of 14C dates within the plateau, 14C samples were collected only from well-defined multilayered contexts. 14C dates from 11 contexts were obtained and these were analyzed using a Bayesian model that incorporated the stratigraphic information. Using this integrative approach we date the Late Bronze Age III levels at Qubur el-Walydah, containing the initial phase of locally produced Philistine pottery between 1185–1140 BC, and the Late Bronze to Iron Age transition between 1140–1095 BC.

Black carbon (BC) from incomplete combustion of organic materials is abundant in many soils. Its age is often higher than that of thermally unaltered soil organic carbon (SOC) owing to the presence of BC from fossil sources or to a high recalcitrance against microbial decomposition compared to that of plant residues. For a meaningful application of radiocarbon as an indicator for soil carbon age and turnover, the relative contribution of BC needs to be quantified, but BC is difficult to separate physically from soil. However, BC is thermally more stable than SOC, and hence thermal stability may provide a quantitative BC indicator. Here, we analyzed 30 light particulate organic carbon (POC) soil fractions for their thermal stability and for their 14C signature. POC is particularly sensitive to “contamination” with BC, because it is obtained by combined size and density fractionation. A steady-state “bomb” 14C model was used to derive mean POC ages. Soils from four sample sets, each consisting of six to eight individual POC samples and representing different field sites and POC types, were analyzed. Samples from one of the sets were virtually BC free, and their mean POC ages ranged from 60 to 100 yr. The 14C signature of samples from the other three sets indicated the presence of very old carbon, with mean POC ages of several hundred and up to 3500 yr. Two indicators for thermal stability—(1) the amount of heat released at temperatures >450°C and (2) the amount of heat released at 500°C (the latter representing the peak temperature of heat released from charcoal isolated from soil)—correlated both significantly and nonlinearly with POC age, indicating that samples with high BC content were older than those with low BC content. It can be concluded that at an individual site with increasing abundance of BC, both the age and the thermal stability of POC increase. However, thermal stability proved to be a reliable predictor for BC in only one sample set, whereas thermal signals of the other two BC-containing sample sets were not significantly different from those of BC-free samples. Thermal stability thus gives no unequivocal indication for the presence of BC in POC across different sites.

In response to the increasing demand for 14C analysis of samples containing less than 25 μg C, ultra-small graphitization reactors with an internal volume of ∼0.8 mL were developed at NOSAMS. For samples containing 6 to 25 μg C, these reactors convert CO2 to graphitic carbon in approximately 30 min. Although we continue to refine reaction conditions to improve yield, the reactors produce graphite targets that are successfully measured by AMS. Graphite targets produced with the ultra-small reactors are measured by using the Cs sputter source on the CFAMS instrument at NOSAMS where beam current was proportional to sample mass. We investigated the contribution of blank carbon from the ultra-small reactors and estimate it to be 0.3 ± 0.1 μg C with an Fm value of 0.43 ± 0.3. We also describe equations for blank correction and propagation of error associated with this correction. With a few exceptions for samples in the range of 6 to 7 μg C, we show that corrected Fm values agree with expected Fm values within uncertainty for samples containing 6–100 μg C.

The radiocarbon activity of benthic foraminifera was investigated in surface sediments from a high deposition rate location at a depth of 1000 m in the Okhotsk Sea. Sediments were preserved and stained with Rose Bengal to identify foraminifera that contain cytoplasm. The benthic fauna at this site is dominated by large specimens of Uvigerina peregrina, and bulk samples (∼150 individuals) of stained and unstained specimens were dated. The stained sample was about 240 14C yr younger than the unstained, and the presence of bomb 14C is inferred by comparison to water column data in the nearby open North Pacific. Using new methods, multiple measurements were also made on samples of three stained and unstained individuals (as small as 7 μg C). Results are consistent with those from the bulk samples. This suggests that similar ultra-small measurements could be made at other locations to reveal the age distribution of individuals in a sediment sample in order to assess the extent of bioturbation and the presence of bomb 14C contamination.

This article presents a compilation of planktic and benthic 14C reservoir ages for the Last Glacial Maximum (LGM) and early deglacial from 11 key sites of global ocean circulation in the Atlantic and Indo-Pacific Ocean. The ages were obtained by 14C plateau tuning, a robust technique to derive both an absolute chronology for marine sediment records and a high-resolution record of changing reservoir/ventilation ages (Δ14C values) for surface and deep waters by comparing the suite of planktic 14C plateaus of a sediment record with that of the atmospheric 14C record. Results published thus far have used as atmospheric 14C reference U/Th-dated corals, the Cariaco planktic record, and speleothems. We have now used the varve-counted atmospheric 14C record of Lake Suigetsu terrestrial macrofossils to recalibrate the boundary ages and reservoir ages of the seven published records directly to an atmospheric 14C record. In addition, the results for four new cores and further planktic results for four published records are given. Main conclusions from the new compilation are the following: (1) The Suigetsu atmospheric 14C record on its varve-counted timescale reflects all 14C plateaus, their internal structures, and relative length previously identified, but implies a rise in the average 14C plateau age by 200–700 14C yr during the LGM and early deglacial times. (2) Based on different 14C ages of coeval atmospheric and planktic 14C plateaus, marine surface water Δ14C may have temporarily dropped to an equivalent of ∼0 yr in low-latitude lagoon waters, but reached >2500 14C yr both in stratified subpolar waters and in upwelled waters such as in the South China Sea. These values differ significantly from a widely assumed constant global planktic Δ14C value of 400 yr. (3) Suites of deglacial planktic Δ14C values are closely reproducible in 14C records measured at neighboring core sites. (4) Apparent deep-water 14C ventilation ages (equivalents of benthic Δ14C), deduced from the sum of planktic Δ14C and coeval benthic-planktic 14C differences, vary from 500 up to >5000 yr in LGM and deglacial ocean basins.

Radiocarbon content in biogenic samples is widely used to study the variation of atmospheric CO2 due to anthropogenic activities. A total of 26 samples of evergreen and deciduous tree leaves, as well as seasonal small plant leaves, were analyzed for this study. Sampling was carried out at the end of the vegetation season from rural villages surrounding a cement factory in Mount Lebanon Province, Lebanon. Reference samples of identical species were collected during the same period from a clean zone. The conventional 14C method was used for the determination of Δ14C values. The data showed that the 14C concentration in the studied sites was significantly lower than the clean area, due to the release of anthropogenic CO2. In order to estimate the Suess effect, the fossil fuel fraction was determined based on equations of mass balance for CO2 concentration, stable isotopic composition of carbon, and 14C concentration. The results showed that selected locations are affected differently according to their distance from the factory and the wind direction.

Lime burials are a characteristic phenomenon of the protohistoric funerary tradition on the Balearic Islands. At Cova de Na Dent, six samples, representing the entire stratigraphy of the lime burial, were taken for analysis. The radiocarbon dates suggested that the lowest levels of the burial were Late Bronze Age. This is in contradiction with the general belief that the lime burials are a late Iron Age phenomenon. Therefore, a new analysis strategy is put forward, focusing on the so-called 1st fraction, the first CO2 released during the acid lime reaction, which is supposed to be free of fossil carbon. The analysis demonstrates the impossibility to eliminate the fossil carbon fraction completely. This is probably due to the different geological formation of the local limestone deposits (ancient reef barriers) compared to the previous lime burials of Mallorca all coming from mountain areas. 14C analysis from a cremation layer without lime at the onset of the lime burial reveals an Iron Age origin of the Cova de Na Dent lime burial.

A 15th century Russian icon from the Novgorod region was analyzed using both dendrochronological and radiocarbon methods [liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS)]. This orthodox icon represents the Mother of God (Dexiokratusa). Fine art experts attribute the icon to between the late 14th to the early 15th centuries. The last complete tree ring was dated to AD 1409. There are indications that the trees were cut down during the summer of AD 1410. Taking into account the time for seasoning (about 8 months), the icon would have been painted in AD 1411. Wiggle-matching of the six AMS samples failed. Two of six AMS dates correspond to dendrochronological dates, while four of the six AMS dates showed differences with the dendrochronological dates by 5–39 yr. This discrepancy raises the issue of a possible regional offset from the calibration curve for the 13th century AD in NW Russia.

This fourth date list for the long cultural sequence in El Mirón Cave (Cantabria, Spain) reports on 19 new AMS assays for Solutrean, Initial, Lower, and Middle Magdalenian and Azilian levels, ranging from about 19 to 11 uncalibrated kyr. Key results are provision of further precision on the transition between the Solutrean and Magdalenian at the end of the Last Glacial Maximum and the very exact dating of a Magdalenian human burial and its relationship to both major living floors and closely associated rock art in the cave.

Northeastern North America has produced an incredible number of late Pleistocene faunal remains; however, many of these were discovered and excavated prior to the development of radiocarbon dating. Moreover, many of the 14C dates that do exist for such specimens were assayed prior to the development of purified collagen extraction methods, were performed on botanical remains of unspecified association with the faunal remains, or were accepted without concerns of young-carbon contamination from museum preservatives. Here, we present a set of high-precision accelerator mass spectrometry (AMS) dates obtained on Pleistocene faunal specimens from Connecticut, New Jersey, and Pennsylvania. Our data contain both newly discovered specimens and specimens that have resided in museum collections for over a century.