bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Coexistence of Man and Extinct Pleistocene Megafauna at Gruta Del Indio (Argentina)
Authors: García Alejandro
Published: July 2016

New excavations and new14C dates at the Gruta del Indio shelter in the central Argentinean Andes show that the dung layer of the site is much thicker towards the front of the site than near the rock wall. This yields a longer chronology for the dung deposit; thus, the upper boundary would date to about 900014C yr BP. The new measurements lengthen the possible time of the coexistence of man and extinct Pleistocene megafauna in the area, since ≃1400 cal yr is much longer than previously thought (Long et al. 1998). Nevertheless, coexistence does not imply interaction, which still is not evident.
Decadal Timescale Shift in the 14C Record of a Central Equatorial Pacific Coral
Authors: Grottoli A G , Gille S T , Druffel E R M , Dunbar R B
Published: July 2016

Coral skeletal radiocarbon records reflect seawater ∆14C and are useful for reconstructing the history of water mass movement and ventilation in the tropical oceans. Here, we reconstructed the inter-annual variability in central equatorial Pacific surface water ∆14C from 1922–1956 using near-monthly 14C measurements in a Porites sp. coral skeleton (FI5A) from the windward side of Fanning Island (3°54′32′′N, 159°18'88′′W). The most pronounced feature in this record is a large, positive shift in the ∆14C between 1947 and 1956 that coincides with the switch of the Pacific Decadal Oscillation (PDO) from a positive to a negative phase in the mid-1940s. Although the absolute ∆14C values from 1950–1955 in FI5A differ from the ∆14C values of another coral core collected from the opposite side of the island, both records show a large, positive shift in their ∆14C records at that time. The relative increase in the ∆14C of each record is consistent with the premise that a common mechanism is controlling the ∆14C records within each coral record. Overall, the Fanning ∆14C data support the notion that a significant amount of subtropical seawater is arriving at the Equator, but does not allow us to determine the mechanism for its transport.
Counting Statistics and Ion Interval Density in AMS
Authors: Vogel John S , Ognibene Ted , Palmblad Magnus , Reimer Paula
Published: July 2016

Confidence in the precisions of accelerator mass spectrometry (AMS) and decay measurements must be comparable for the application of the radiocarbon calibration to age determinations using both technologies. We confirmed the random nature of the temporal distribution of 14C ions in an AMS spectrometer for a number of sample counting rates and properties of the sputtering process. The temporal distribution of ion counts was also measured to confirm the applicability of traditional counting statistics.
Late Glacial 14C Ages from a Floating, 1382-Ring Pine Chronology
Authors: Kromer Bernd , Friedrich Michael , Hughen Konrad A , Kaiser Felix , Remmele Sabine , Schaub Matthias , Talamo Sahra
Published: July 2016

We built a floating, 1382-ring pine chronology covering the radiocarbon age interval of 12,000 to 10,650 BP. Based on the strong rise of Δ14C at the onset of the Younger Dryas (YD) and wiggle-matching of the decadal-scale Δ14C fluctuations, we can anchor the floating chronology to the Cariaco varve chronology. We observe a marine reservoir correction higher than hitherto assumed for the Cariaco site, of up to 650 yr instead of 400 yr, for the full length of the comparison interval. The tree-ring Δ14C shows several strong fluctuations of short duration (a few decades) at 13,800; 13,600; and 13,350 cal BP. The amplitude of the strong Δ14C rise at the onset of the YD is about 40, whereas in the marine data set the signal appears stronger due to a re-adjustment of the marine mixed-layer Δ14C towards the atmospheric level.
A Radiocarbon Perspective on Greenland Ice-Core Chronologies: Can we Use Ice Cores for 14C Calibration?
Authors: Southon John
Published: July 2016

Some of the most valuable paleoclimate archives yet recovered are the multi-proxy records from the Greenland GISP2 and GRIP ice cores. The crucial importance of these data arises in part from the strong correlations that exist between the Greenland δ18O records and isotopic or other proxies in numerous other Northern Hemisphere paleoclimate sequences. These correlations could, in principle, allow layer-counted ice-core chronologies to be transferred to radiocarbon-dated paleoclimate archives, thus providing a 14C calibration for the Last Glacial Maximum and Isotope Stage 3, back to the instrumental limits of the 14C technique. However, this possibility is confounded by the existence of numerous different chronologies, as opposed to a single (or even a “best”) ice-core time scale. This paper reviews how the various chronologies were developed, summarizes the differences between them, and examines ways in which further research may allow a 14C calibration to be established.
14C Dates and the Iron Age Chronology of Israel: A Response
Authors: Mazar Amihai , Bronk Ramsey Christopher
Published: July 2016

Boaretto et al. (2005) published 68 radiocarbon dates relating to 30 samples from 10 Iron Age sites in Israel as part of their Early Iron Age Dating Project. Though the main goal of their paper was an interlaboratory comparison, they also presented results of Bayesian models, calculating the transition from Iron Age I to Iron Age II in Israel to be about 900 BCE instead of the conventional date of about 1000 BCE. Since this date has great importance for all of Eastern Mediterranean archaeology, in this paper we examine the results in light of the dates published in the above-mentioned article. Our paper was revised in light of new data and interpretations published by Sharon et al. (2007).

Following a survey of the contexts and specific results at each site, we present several Bayesian models. Model C2 suggests the date range of 961–942 BCE (68% probability) for the transition from Iron Age I to Iron Age II, while Model C3 indicates a somewhat later date of 948–919 BCE (compare the date 992–961 BCE calculated at Tel Rehov for the same transition). In our Model D, we calculated this transition date at Megiddo as taking place between 967–943 BCE. Finally, we calculated the range of dates of major destruction levels marking the end of the Iron Age I, with the following results: Megiddo VIA: 1010–943 BCE; Yoqne'am XVII: 1045–997 BCE; Tell Qasile X: 1039–979 BCE; Tel Hadar: 1043–979 BCE (all in the 68.2% probability range). Figure 4 indicates that the transition between Iron I and II probably occurred between these above-mentioned destruction events and the dates achieved in our Models C2 or C3, namely during the first half of the 10th century BCE.

This study emphasizes the sensitivity of Bayesian models to outliers, and for reducing or adding dates from the models. This sensitivity should be taken into account when using Bayesian models for interpreting radiometric dates in relation to subtle chronological questions in historical periods.
Radiocarbon Chronology of Central Alaska: Technological Continuity and Economic Change
Authors: Potter Ben A
Published: July 2016

This research presents the first comprehensive radiocarbon chronology for central Alaska, encompassing the late Pleistocene and Holocene archaeological record. Dated component distributions, comprised of 274 14C dates from 160 components, indicate changing land-use strategies and subsistence economies, reflecting primarily lowland exploitation of bison, wapiti, and birds prior to 6000 cal B P, followed by increasing caribou and fish exploitation and use of upland areas. Microblade technology is conserved from the earliest components to ~1000 cal B P, and this continuity is not reflected in current cultural history sequences. Using component abundance as a proxy for population, initial colonization is associated with climate amelioration after ~14,000 cal BP, and population declines are associated with the Younger Dryas (13,000–12,000 cal BP) and initial establishment of widespread spruce forests (10,000–9000 cal BP).
AMS Radiocarbon Dating of Giant Rock Scallop (Hinnites Multirugosus) Artifacts from San Miguel Island, California, USA
Authors: Braje Todd J , Rick Torben C , Erlandson Jon M
Published: July 2016

For at least 100,000 yr, marine shell beads have been important ornamental and symbolic artifacts intimately associated with the behavior of anatomically modern humans. In California, giant rock scallop (Hinnites multirugosus) beads were once thought to have been used only for the last 1000 yr, where they were considered to be markers of high social status among the Chumash Indians of the Santa Barbara Channel region. Direct accelerator mass spectrometry (AMS) radiocarbon dating of 1 giant rock scallop ornament and 2 beads from San Miguel Island extends the use of this shell for personal adornment to at least 8000 cal BP. Our study emphasizes the importance of direct AMS14C dating of artifacts to enhance cultural chronologies and clarify the antiquity of various technologies and associated behaviors. Our results also caution archaeologists when equating artifact rarity with sociopolitical complexity.
The Mysterious 14C Decline
Authors: Broecker Wallace
Published: July 2016

Fundamental to the field of radiocarbon dating is not only the establishment of the temporal record of the calendar age-radiocarbon age offsets but also the development of an understanding of their cause. Although part of the decline in the magnitude of this offset over the past 40,000 can be explained by a drop in 14C production rate associated with a progressive increase in the strength of the Earth's magnetic shielding, it is clear that changes in the distribution of 14C among the Earth's active carbon reservoirs are also required. In particular, the steep 15% decline in the 14C to C ratio in atmospheric CO2 and surface ocean ΣCO2, which occurred in a 3 kyr-duration interval marking the onset of the last deglaciation, appears to require that a very large amount (at least 5000 gigatons) of 14C-deficient carbon was transferred to or within the ocean during this time interval. As no chemical or stable isotope anomaly associated with this injection appears in either the marine sediment or polar ice records, this injection must involve a transfer within the ocean (i.e. a mixing of 2 ocean reservoirs, one depleted in 14C and the other enriched in 14C). Although evidence for the existence of a salt-stabilized glacial-age abyssal ocean reservoir exists, a search based on benthic-planktic age differences and 13C measurements appears to place a limit on its size well below that required to account for the steep 14C decline.
Archaeology Introduction
Authors: Renfrew Colin
Published: July 2016

The radiocarbon revolution may be seen in retrospect as the most decisive development in the archaeology of the 20th century. It is a pleasure, therefore, to have the opportunity of congratulating Radiocarbon on its jubilee celebration, and on the significant role that it has played in establishing a level of excellence in publication, against which the advances in that revolution could be measured. I well remember, as an undergraduate in Cambridge starting to read archaeology in 1960, how each new issue of Radiocarbon would be scrutinized for new dates bearing upon European prehistory. Glyn Daniel, then editor of Antiquity, would often begin a lecture with the announcement of some improbably early date for a Neolithic monument in Brittany or in Britain. It was clear that archaeology was being transformed, but not yet evident what the nature of the transformation would be.
Six Decades of Radiocarbon Dating in New World Archaeology
Authors: Taylor R E
Published: July 2016

Radiocarbon (14C) dating provided New World archaeological research with the first continent-wide common chronometric scale that transcended the mostly relative site- and region-specific chronological sequences that had been assembled during the preceding century of fieldwork.14C data continue to play a critical role in establishing a chronometric framework for the 5-century-long debate concerning the timing of the initial peopling of the New World. Other issues where14C results have been of particular importance include the origins and development of New World agriculture and determination of the relationship between the Western and Classic Maya long-count calendar. The introduction of a third-generation measurement technology of accelerator mass spectrometry (AMS) beginning in the late 1970s has provided a means of obtaining analyses on milligram and microgram amounts of carbon permitting more detailed critical approaches to increasing the accuracy of14C values on certain sample types—particularly human skeletal materials. It also provided a more effective means of allowing greater dating precision in situations where such data had an important bearing on the validity of inferences about the rates of cultural evolutionary change in New World societies.
The Radiocarbon Calibration from An Irish Oak Perspective
Authors: Baillie Mike G L
Published: July 2016

Between 1968 and 1984, a 7272-yr oak chronology was constructed in Belfast, Northern Ireland, in order to provide a local calibration of the radiocarbon timescale. This single-minded exercise in chronology construction provided an exciting occupation for a group of researchers that can be likened to a race in which there was no guarantee of a finish. The existence of a parallel dendrochronological enterprise in Germany added both competition and the possibility of independent replication. The initial completion of both chronologies by 1984, and respective calibrations by 1986, left an important legacy of 2 absolutely dated tree-ring chronologies for multifarious research purposes.
Late Holocene14C Marine Reservoir Corrections for Hawai'I Derived from U-Series Dated Archaeological Coral
Authors: Weisler Marshall I , Hua Quan , Zhao Jian-xin
Published: July 2016

The first application of U-series dating and accelerator mass spectrometry (AMS) assay of Polynesian archaeologicalPocilloporaspp. branch corals for deriving a precise local marine reservoir correction (ΔR) is described. Known-age corals were selected that spanned the entire culture-historical sequence for the Hawaiian Islands, thus eliminating the problem of not having known-age dated samples that cover the period of direct relevance to prehistorians; in this case, about AD 700–1800. Dating coral samples from windward and leeward coastlines of Moloka'i Island, with different offshore conditions such as upwelling, currents, wind patterns, coastal topography, and straight or embayed shorelines, provides insights into possible variations of local conditions on the same island—something that has never been attempted. In this regard, there was no spatial variability in ΔR during the 17th century. We report a weighted average ΔR value for Moloka'i Island of 52 ± 25 yr using 12 pair-dated dedicatory branch corals from religious archaeological sites and demonstrate that there is no significant temporal variability in ΔR between about AD 700 to 1800. In combination with 4 selected previously published ΔR values based on pre-bomb known-age marine shells, a revised ΔR of 66 ± 54 yr is established for the Hawaiian Islands. However, future research should examine the archipelago-wide spatial variability in ΔR with the analysis of additional dated archaeological coral samples.
Variations in 14C Reservoir Ages of Black Sea Waters and Sedimentary Organic Carbon During Anoxic Periods: Influence of Photosynthetic Versus Chemoautotrophic Production
Authors: Fontugne Michel , Guichard François , Bentaleb Ilham , Strechie Claudia , Lericolais Gilles
Published: July 2016

Radiocarbon activity of dissolved inorganic carbon has been measured in the northwestern Black Sea. Both continental shelf and open-sea profiles show that surface waters are in equilibrium with the atmosphere. The observed distribution of 14C activity shows a weak contribution of the deep 14C-depleted CO2 to the photic zone. Such a distribution of 14C within the water column is unable to explain the aging of sedimentary organic matter and reservoir ages greater than 500 yr. A contribution of production by chemoautotrophic bacteria feeding on 14C-depleted methane at the boundary of the oxic and anoxic zones is a realistic hypothesis. Also, a contribution to sedimentary organic carbon estimated at <15% of the photosynthetic primary production could explain 14C reservoir ages greater than 1300 yr.
A Protocol for Radiocarbon Dating Tropical Subfossil Cave Guano
Authors: Wurster Christopher M , Bird Michael I , Bull Ian , Bryant Charlotte , Ascough Philippa
Published: July 2016

We present accelerator mass spectrometry (AMS) radiocarbon dates on several organic fractions isolated from tropical guano deposits recovered from insular Southeast Asia. Differences were observed between 14C measurements made on bulk guano as well as bulk lipids, the saturated hydrocarbon fraction, solvent-extracted guano, and insect cuticles extracted from the same bulk sample. We infer that 14C dates from the bulk lipid fraction and saturated hydrocarbon fractions can be variably contaminated by exogenous carbon. In contrast, 14C measurements on solvent-extracted guano and isolated insect cuticles appear to yield the most robust age determinations.
Direct Analysis of Automotive Fuels for Bioethanol Content Using Radiocarbon Analysis
Authors: Norton Glenn A
Published: July 2016

Exploratory work was performed to investigate the feasibility of using a simplified radiometric analytical approach for determining the bioethanol content of US automotive fuels. The method involves mixing fuel samples directly with a suitable fluor. Sample preparation is extremely rapid since all conventional sample preparation steps are essentially eliminated. Results are based on the background-corrected DPM values obtained when using 10 mL of sample mixed with 10 mL of Permafluor E+. Results are also reported in terms of conventional pMC for some of the samples. Bioethanol from a dry-mill ethanol plant served as the analytical reference sample that represented a 100% bioethanol content. Using current-day bioethanol as a reference sample eliminates the need to correct for “bomb carbon.” For 1:1 mixtures of sample and fluor, the background-corrected DPM showed a linear relationship with the bioethanol concentration, indicating that the quench correction approach was effective for the variable-quench samples. Based on the analysis of E0 (pure gasoline), E10, and “E85” from local gas stations, it appears that the method has good potential for determining the bioethanol content in commercial ethanol/gasoline blends. However, a variety of potential sources of error still require investigation in order to refine the method.
Dealing with Outliers and Offsets in Radiocarbon Dating
Authors: Bronk Ramsey Christopher
Published: July 2016

The wide availability of precise radiocarbon dates has allowed researchers in a number of disciplines to address chronological questions at a resolution which was not possible 10 or 20 years ago. The use of Bayesian statistics for the analysis of groups of dates is becoming a common way to integrate all of the 14C evidence together. However, the models most often used make a number of assumptions that may not always be appropriate. In particular, there is an assumption that all of the 14C measurements are correct in their context and that the original 14C concentration of the sample is properly represented by the calibration curve.

In practice, in any analysis of dates some are usually rejected as obvious outliers. However, there are Bayesian statistical methods which can be used to perform this rejection in a more objective way (Christen 1994b), but these are not often used. This paper discusses the underlying statistics and application of these methods, and extensions of them, as they are implemented in OxCal v 4.1. New methods are presented for the treatment of outliers, where the problems lie principally with the context rather than the 14C measurement. There is also a full treatment of outlier analysis for samples that are all of the same age, which takes account of the uncertainty in the calibration curve. All of these Bayesian approaches can be used either for outlier detection and rejection or in a model averaging approach where dates most likely to be outliers are downweighted.

Another important subject is the consistent treatment of correlated uncertainties between a set of measurements and the calibration curve. This has already been discussed by Jones and Nicholls (2001) in the case of marine reservoir offsets. In this paper, the use of a similar approach for other kinds of correlated offset (such as overall measurement bias or regional offsets in the calibration curve) is discussed and the implementation of these methods in OxCal v 4.0 is presented.
Reanalysis of the Chronological Discrepancies Obtained by the Old and Middle Kingdom Monuments Project
Authors: Dee M W , Bronk Ramsey C , Shortland A J , Higham T F G , Rowland J M
Published: July 2016

The most extensive chronometric study ever undertaken on Egyptian Dynastic sites was published inRadiocarbonby Bonani et al. (2001). It comprised 269 radiocarbon measurements on monuments ranging from the 1st–12th dynasties. However, many of the calibrated dates obtained were significantly offset from historical estimates. The greatest discrepancies occurred in the 4th Dynasty where, paradoxically, the dating program had been most rigorous. For this period, 158 measurements were made at 12 sites, with the majority of the dates being 200–300 yr older than expected. The 4th Dynasty results were especially significant as they included some of the most important monuments in Egypt. In this paper, the raw data from that study have been reanalyzed using the OxCal calibration program, making particular use of its new outlier detection functionality. This Bayesian approach has resulted in a new series of calibrations that show much closer agreement with conventional chronological records.
Dating of Groundwater Recharge in Two Small Adjacent Aquifers in Israel and Their Initial 14C Activities
Authors: Guttman J , Kronfeld J , Carmi I
Published: July 2016

Radiocarbon and tritium determinations were carried out in 2 adjacent small aquifers in Israel. These aquifers have small storage capacities and good hydraulic properties. Darcy calculations suggest that the aquifers contain young waters, ≃50 yr in age. 14C concentrations in the Pleistocene aquifer are between 23–60 pMC, with the lowest activity related to contamination by petroleum-based fertilizers with no 14C. 14C concentrations in the Judea Group aquifer range from 62 to 95 pMC. An apparent difference of ≃1000 yr is indicated for the average recharge age between the 2 aquifers. The tritium data suggests that the water in both aquifers is quite young. The 1000-yr difference is an artifact of initial isotopic fractionation differences through the unsaturated zone as established elsewhere for these 2 aquifers. When these individual fractionation factors (0.54 for the Pleistocene and 0.62 for the Judea Group) are used, it is revealed that both aquifers contain young water, in agreement with the Darcy calculation, which was recharged at the beginning of the period of thermonuclear atmospheric testing in the early 1960s.
Sampling Iron for Radiocarbon Dating: Influence of Modern Steel Tools on 14C Dating of Ancient Iron Artifacts
Authors: Hüls Matthias , Grootes Pieter M , Nadeau Marie-Josée
Published: July 2016

Before the 17th century, charcoal was regularly used in the production of iron (smelting and forging) and some of this charcoal carbon was incorporated into the iron. Depending on the age of the wood used to produce the charcoal, the age of the carbon incorporated in the iron lattice can reflect the age of manufacture of the iron artifacts. A reliable preparation method allowing for the routine dating of iron artifacts would permit the dating of numerous objects for which now the age can only be estimated. In an earlier work (Hüls et al. 2004), we tested the extraction of carbon from iron samples by closed-tube combustion. The samples were cut in small pieces to ease the release of the carbon from the lattice. During the tests, it became clear that the steel tools used to cut the samples can add contamination at the surface. As modern steel is made using coal, this leads to erroneously old ages. We have tested ways to reduce or eliminate this surface contamination from the sampling tools using iron artifacts of known ages. In order to quantify the contamination, we produced standard test materials from pure iron (99.998% Fe) melted with carbon of known 14C content and prepared samples using different cutting tools. The results of these tests indicate that the proper choice of cutting technique and tool, combined with an additional cleaning of the freshly cut surface, reduces sample contaminations to low levels; measured sample 14C concentrations are close to the 14C content of the charcoal used to produce these standard iron samples.
Antarctic Radiocarbon Reservoir: The Case of the Mummified Crabeater Seals (Lobodon Carcinophaga) in Bodman Cape, Seymour Island, Antarctica
Authors: Negrete Javier , Soibelzon Esteban , Tonni Eduardo P , Carlini Alejandro , Soibelzon Leopoldo H , Poljak Sebastián , Huarte Roberto A , Carbonari Jorge E
Published: July 2016

At least 50% of the world's seal population is distributed in the pack-ice region surrounding Antarctica. Among the Antarctic seals, Lobodon carcinophaga (commonly known as “crabeater seals”) are the most abundant. This is a krill-feeding species, subsisting primarily on Euphausia superba. The occurrence of mummified seals has been documented since 1900 in several Antarctic regions, and different hypotheses about age and what happened to them have been proposed. Taking into account the depletion of 14C concentration in marine waters, we dated a recently deceased and a mummified L. carcinophaga along with a mollusk (Nacella concinna) collected alive from different locations around Antarctica. We discuss their relationship in light of the 14C reservoir. The age obtained for the recently deceased crabeater seals suggests a reservoir age of around 1300 yr for these waters, which is in agreement with the correction value for reservoir age obtained for the same species in the area. We applied this reservoir correction value to the conventional age of 1180 14C yr BP obtained for the mummified seal. The results indicate that the death event probably occurred within the last 100 yr. The age obtained for the mollusk specimen confirms that the correction values of the reservoir effect for the Antarctic continent vary according to geographical location and to the type of sample dated.
Obituary: Jacques Labeyrie (1920–2011)
Authors: Paterne Martine
Published: July 2016

After more than 50 years dedicated to scientific research and to the dissemination of knowledge, Dr Jacques Labeyrie recently passed away at the age of 91. Upon graduating from the Ecole Supérieure de Physique et Chimie Industrielle de la Ville de Paris (1940–43), he became the assistant to Frédéric Joliot-Curie at the Collège de France. With Joliot's recommendation, he was recruited in 1946 to the Commissariat à l'Energie Atomique (CEA), where he stayed until his retirement in 1985. He was named Head of the Section d'Electronique Physique (later known as the Service d'Electronique Physique) of the CEA in 1955, which he managed until 1982.
A Comparison of Bone Pretreatment Methods for AMS Dating of Samples >30,000 BP
Authors: Talamo Sahra , Richards Mike
Published: July 2016

Bone is a commonly used material for radiocarbon dating, yet at ages close to the limit of the method (>30,000 BP), it is a substantial challenge to remove contamination and produce accurate ages. We report here on the preliminary results of a dating study of 2 bones older than 30,000 yr, which were each treated with a suite of pretreatment procedures, including ultrafiltration (Brown et al. 1988). Substantial differences in the 14C ages were observed, which is most likely linked to crucial steps in the removal of contamination both in the bone and in the laboratory. Using a comprehensive sequence of pretreatment procedures, including ultrafiltration, we obtain generally older ages.
Dating the Lascaux Cave Gour Formation
Authors: Genty D , Konik S , Valladas H , Blamart D , Hellstrom J , Touma M , Moreau C , Dumoulin J-P , Nouet J , Dauphin Y , Weil R
Published: July 2016

Lascaux Cave is renowned for its outstanding prehistoric paintings, strikingly well-preserved over about 18,000 yr. While stalagmites and stalactites are almost absent in the cave, there is an extensive calcite flowstone that covered a large part of the cave until its opening for tourists during the 1950s. The deposit comprises a succession of calcite rims, or “gours,” which allowed seepage water to pond in large areas in the cave. Their possible role in preservation of the cave paintings has often been evoked, but until now this deposit has not been studied in detail. Here, we present 24 new radiocarbon accelerator mass spectrometry (AMS) and 6 uranium-thorium (U-Th) analyses from the calcite of the gours, 4 AMS 14C dates from charcoals trapped in the calcite, and 4 AMS 14C analyses on organic matter extracted from the calcite. Combining the calibrated 14C ages obtained on charcoals and organic matter and U-Th ages from 14C analyses made on the carbonate, has allowed the calculation of the dead carbon proportion (dcp) of the carbonate deposits. The latter, used with the initial atmospheric 14C activities reconstructed with the new IntCal09 calibration data, allows high-resolution age estimation of the gour calcite samples and their growth rates. The carbonate deposit grew between 9530 and 6635 yr cal BP (for dcp = 10.7 ± 1.8%; 2 σ) or between 8518 and 5489 yr cal BP (for dcp = 20.5 ± 1.9%; 2 σ). This coincides with humid periods that can be related to the Atlantic period in Europe and to Sapropel 1 in the eastern Mediterranean Sea. However, geomorphological changes at the cave entrance might also have played a role in the gour development. In the 1940s, when humans entered the cave for the first time since its prehistoric occupation, the calcite gours had already been inactive for several thousand years.
High-Precision Radiocarbon Measurements of Tree-Ring Dated Wood from New Zealand: 195 Bc–Ad 995
Authors: Hogg Alan , Palmer Jonathan , Boswijk Gretel , Turney Chris
Published: July 2016

The best means for correcting Southern Hemisphere (SH) radiocarbon measurements, which are significantly influenced by temporal variations in the interhemispheric offset, is by the construction of a SH-specific calibration curve from dendrochronologically dated wood. We present here decadal 14C measurements on dendrochronologically secure New Zealand kauri (Agathis australis), covering the period 195 BC–AD 995, extending the range of calibration measurements from New Zealand tree rings to more than 2 millennia.

Recently published Tasmanian huon pine (Lagarostrobos franklinii) data for the interval 165 BC to AD 1095 measured at the Center for Accelerator Mass Spectrometry (CAMS) have underestimated standard errors, which need to be re-assessed before the data can be considered for a Southern Hemisphere calibration curve update. The CAMS huon data, unlike the Waikato kauri data presented here, show a significant reduction in the SH offset for the interval AD 775–855. Although these data points are being checked, it is unlikely this represents a temporal geographic location-dependent offset. With re-assessed errors, the huon data set from 165 BC to AD 995 closely matches the new kauri data, with the combined data sets producing a mean interhemispheric offset with IntCal09 of 44 ± 17 yr for the time interval 195 BC–AD 1845. This SH offset is lower than the modeled offset of 55–58 yr used in the construction of SHCal04, and we recommend the lower value be used in future SHCal updates. Although there is an apparent increase in higher frequency events in the SH offset (NZ kauri plus Tasmanian huon) from 200 BC–AD 1000, the reason for this remains unclear.
Testing the “Dicarb Problem”: A Case Study from North Alaska
Authors: Reuther Joshua D , Gerlach S Craig
Published: July 2016

An assumption exists in North Alaskan archaeological literature that radiometric assays produced by the now-defunct Dicarb Radioisotope Co. (Dicarb) are “too young” or more recent when compared to those produced by other laboratories. This assumption is statistically tested by comparing radiocarbon assays produced by Dicarb to those produced by Beta Analytic, Inc.; Geochron Laboratories; and the NSF-Arizona AMS Facility. The primary data set consists of radiometric and accelerator mass spectrometry (AMS) assays produced from materials excavated at the Croxton site, Locality J, Tukuto Lake, northern Alaska. Statistical analyses demonstrate that 14C assays produced by Dicarb tend to be “younger” than assays produced by other laboratories on crosscheck samples, with differences ranging between 350 and 1440 yr.
Diet-Derived Variations in Radiocarbon and Stable Isotopes: A Case Study from Shag River Mouth, New Zealand
Authors: Higham Thomas , Anderson Atholl , Ramsey Christopher Bronk , Tompkins Christine
Published: July 2016

Accelerator mass spectrometry (AMS) determinations of rat bones from natural and cultural sites in New Zealand have produced ages at odds with the accepted date for early human settlement by over 1000 yr. Since rats are a human commensal, this implies either an earlier visitation by people or problems with the reliability of the AMS determinations. One explanation for the extreme ages is dietary variation involving movement of depleted radiocarbon through dietary food chains to rats. To investigate this, we 14C dated fauna from the previously well-dated site of Shag River Mouth. The faunal remains were of species that consumed carbon derived from a variety of environments within the orbit of the site, including the estuary, river, land, and sea. The 14C results showed a wide range in age among estuarine and freshwater species. Terrestrial and marine organisms produced ages within expectations. We also found differences between bone dated using the Oxford ultrafiltration method and those treated using the filtered gelatin method. This implies that contamination could also be of greater importance than previously thought.
Re-Dating Mid-Holocene Betelnut (Areca Catechu L.) and Other Plant Use at Dongan, Papua New Guinea
Authors: Fairbairn Andrew , Swadling Pamela
Published: July 2016

Direct accelerator mass spectrometry (AMS) dating of anaerobically preserved plant remains from the Dongan site in New Guinea, combined with assessment of preservation condition, confirms earlier doubts about the antiquity of betelnut (Areca catechu L.) found at the site. A possible sago leaf fragment is also identified as a modern contaminant. The mid-Holocene age of other fruit and nut remains is verified using these methods. The utility of AMS dating in combination with detailed archaeobotanical assessment is demonstrated, thus improving chronometric hygiene and with it knowledge of past plant use in Oceania.
Radiocarbon Determination of Particulate Organic Carbon in Non-Temperated, Alpine Glacier Ice
Authors: Steier Peter , Drosg Roswitha , Fedi Mariaelenea , Kutschera Walter , Schock Martin , Wagenbach Dietmar , Wild Eva Maria
Published: July 2016

Dating ice samples from glaciers via radiocarbon is a challenge that requires systematic investigations. This work describes an approach for extraction and accelerator mass spectrometry (AMS) 14C analysis of the particulate organic carbon (POC) fraction in glacier ice samples. Measurements were performed at VERA (Vienna Environmental Research Accelerator) on ice samples obtained mainly from the non-temperated ablation zone of the Grenzgletscher (Grenz Glacier) system (Monte Rosa Massif, Swiss Alps). The samples were obtained from 2 sampling sites situated roughly on a common flow line. The sample masses used were between 0.3 and 1.4 kg of ice, yielding between 18 and 307 μg of carbon as POC. The carbon contamination introduced during sample processing varied between 5.4 and 33 μg C and originated mainly from the quartz filters and the rinsing liquids used in processing. Minimum sample sizes for successful graphitization of CO2 in our laboratory could be reduced to <10 μg carbon, with a background in the graphitization process of ∼0.5 μg of 40-pMC carbon. Evaluation of the whole procedure via 11 Grenzgletscher samples revealed a surprisingly large scatter of pMC values. We obtain a mean calibrated age of 2100 BC to AD 900 (95.4% confidence level), which is not significantly different for the 2 sampling sites. Discussions of these results suggest that single 14C dates of glacial POC are presently of limited significance. Future improvements with respect to analytical precision and sample characterization are proposed in order to fully explore the POC dating potential.
Paired 14C and 230Th/U Dating of Surface Corals from the Marquesas and Vanuatu (Sub-Equatorial Pacific) in the 3000 to 15,000 Cal Yr Interval
Authors: Paterne Martine , Ayliffe Linda K , Arnold Maurice , Cabioch Guy , Tisnérat-Laborde Nadine , Hatté Christine , Douville Eric , Bard Edouard
Published: July 2016

Paired radiocarbon and 230Th/U dating was performed on 13 surface corals from submerged reefs in the Marquesas and from raised terraces in Vanuatu. The absolute ages of the corals analyzed ranged from 3000 to 15,000 cal yr. Estimates of the difference between the absolute and 14C ages of these corals are in agreement with previous determinations up until 11,500 cal yr. The resulting mean sea surface reservoir age R is determined at 390 ± 60 yr for the Marquesas region (9°S), which is slightly higher than the R value at 280 ± 50 yr for the Tahiti Islands (18°S). Multiple 14C analyses of 2 corals from the Marquesas present scattered 14C ages at ~12,000 and ~15,100 cal yr. This could be attributed to rapid changes of the 14C content of surface waters around the Marquesas Islands or to a subtle submarine diagenesis.
The ‘Sterno-Etrussia’ Geomagnetic Excursion Around 2700 BP and Changes of Solar Activity, Cosmic Ray Intensity, and Climate
Authors: Dergachev V A , Raspopov O M , van Geel B , Zaitseva G I
Published: July 2016

The analysis of both paleo- and archeomagnetic data and magnetic properties of continental and marine sediments has shown that around 2700 BP, the geomagnetic Sterno-Etrussia excursion took place in 15 regions of the Northern Hemisphere. The study of magnetic properties of sediments of the Barents, Baltic, and White Seas demonstrates that the duration of this excursion was not more than 200–300 yr.

Paleoclimatic data provide extensive evidence for a sharp global cooling around 2700 B P. The causes of natural climate variation are discussed. Changes of the galactic cosmic ray intensity may play a key role as the causal mechanism of climate change. Since the cosmic ray intensity (reflected by the cosmogenic isotope level in the earth's atmosphere) is modulated by the solar wind and by the terrestrial magnetic field, this may be an important mechanism for long-term solar climate variability. The Sterno-Etrussia excursion may have amplified the climate shift, which, in the first place, was the effect of a decline of solar activity. During excursions and inversions, the magnetic moment decreases, which leads to an increased intensity of cosmic rays penetrating the upper atmosphere. Global changes in the electromagnetic field of the earth result in sharp changes in the climate-determining factors in the atmosphere, such as temperatures, total pressure field, moisture circulation, intensity of air flows, and thunderstorm activity. In addition, significant changes in the ocean circulation patterns and temperature regimes of oceans will have taken place.
Differentiating Bone Osteonal Turnover Rates By Density Fractionation; Validation Using the Bomb14C Atmospheric Pulse
Authors: Young Shin Ji , O'Connell Tamsin , Black Stuart , Hedges Robert
Published: July 2016

The density (BSG) of bone increases, at the osteon scale, during lifetime aging within the bone. In addition, post-mortem diagenetic change due to microbial attack produces denser bioapatite. Thus, fractionation of finely powdered bone on the basis of density should not only enable younger and older populations of osteons to be separated but also make it possible to separate out a less diagenetically altered component. We show that the density fractionation method can be used as a tool to investigate the isotopic history within an individual's lifetime, both in recent and archaeological contexts, and we use the bomb14C atmospheric pulse for validating the method.
Levels of 14C in the Terrestrial Environment in the Vicinity of Two European Nuclear Power Plants
Authors: Magnusson åsa , Stenström Kristina , Skog Göran , Adliene Diana , Adlys Gediminas , Hellborg Ragnar , Olariu Agata , Zakaria Mohamad , Rääf Christopher , Mattsson Sören
Published: July 2016

Radiocarbon is produced in all types of nuclear reactors. Most of the 14C released into the environment is in the form of gaseous emissions. Recent data on the 14C concentration found in terrestrial samples taken in the vicinity of nuclear power plants in Romania and Lithuania are presented. We found increased 14C levels in the surroundings of both power plants. At the Romanian power plant Cernavoda, we found excess levels of 14C in grass within a distance of about 1000 m, the highest 14C specific activity being 311 Bq/kg C (approximately 28% above the contemporary 14C background) found at a distance of 200 m from the point of release (nearest sampling location). At the Lithuanian power plant Ignalina, samples of willow, pine, and spruce showed a 14C excess of similar magnitude, while significantly higher values were found in moss samples. The samples were analyzed at the accelerator mass spectrometry facility in Lund, Sweden.
University of Michigan Radiocarbon Dates XIII
Authors: Crane H. R. , Griffin James B.
Published: July 2016

The following is a list of dates obtained since the compilation of List XII. The method is essentially the same as described in that list. Two CO2-CS2Geiger counter systems were used. Equipment and counting techniques have been described elsewhere (Crane, 1961). Dates and estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conferences of 1962 and 1965, in that (a) dates are computed on the basis of the Libby half-life, 5570 yr, (b) a.d. 1950 is used as the zero of the age scale, and (c) the errors quoted are the standard deviations obtained from the numbers of counts only. In Michigan date lists up to and including VII, we quoted errors at least twice as great as the statistical errors of counting, to take account of other errors in the over-all process.
Smithsonian Institution Radiocarbon Measurements VI
Authors: Stuckenrath Robert , Mielke James E.
Published: July 2016

This list includes those analyses completed December, 1968, with equipment and procedures previously employed here.
University of Texas at Austin Radiocarbon Dates VII
Authors: Valastro S. , Davis E. Mott
Published: July 2016

This list reports C14measurements made in dating projects completed in the year ending December, 1968, and some measurements for projects still in progress. Age calculations are based on C14half-life of 5568 yr and a modern standard of 95% of NBS oxalic acid. Deviations reported are based on counting statistics of sample, background, and modern, and are ±1σ except that when sample count approaches either modern or background, 2σ limits are reported. The laboratory uses liquid scintillation counting of benzene, with Li2C2and vanadium activated catalyst in preparation, as described in Texas IV (Radiocarbon, 1966, v. 8, p. 453–466) and earlier lists. Chemical yields average 85%.
University of Saskatchewan Radiocarbon Dates III
Authors: McCallum K. J. , Wittenberg J.
Published: July 2016

The third series of C14measurements made at the University of Saskatchewan is reported in the present list. The equipment and methods have been described previously (Saskatchewan II). The modern reference standard was 0.950 times the activity of the NBS oxalic-acid standard. The activity of the wood standard used previously corresponded to 0.955 ± 0.009 of the NBS standard, so that no corrections are required to the previous date lists to bring them into line.
Geological Survey of Finland Radiocarbon Measurements I
Authors: Hyyppä E. , Hoffrén V. , Isola A.
Published: July 2016

The C14-laboratory at the Geological Survey of Finland was started in October 1960 in order to determine ages of Quaternary objects. Only 11 samples that have been measured are ready to be published. Most samples in the following list have been measured many times in order to control the stability of the system and to make all necessary corrections. The C14-system includes two CO2-filled proportional counters. Until now the measurements have used only the first counter system. The second one is now ready for dating.
UCLA Radiocarbon Dates I
Authors: Fergusson G. J. , Libby W. F.
Published: July 2016

The measurements reported in this list have been made since the Radiocarbon Dating Laboratory at the Institute of Geophysics, UCLA became operational in August 1961. CO2proportional counting was used for all measurements in an 7 · 5-L counter at 1 atm pressure. Dates have been calculated on the basis of the C14half life of 5568 ± 30 yr, and 95% of NBS oxalic acid as modern standard. It is planned to discuss the half life in the light of the newer measurements at a conference in 1962. Prior to general agreement as to the new best figure we propose that all dates continue to be calculated on the old basis. Samples have been carefully inspected, cleaned, picked free of rootlets, and pretreated with HCl when necessary.
Stockholm Natural Radiocarbon Measurements IV
Authors: Engstrand Lars G. , Östlund H. Göte
Published: July 2016

This paper is a direct continuation of the third dating list (Stockholm III), and the entire technique is virtually unchanged, using one 0.5–1 and one 1.0.1 3 atm CO2proportional counter. Ages are calculated according to the recommendation given in the introduction of this book, and δC13has been measured for unknown samples and for the different CO2preparations of the NBS oxalic-acid standard. Since the numerical relationship between the C14activity of our old oak standard and that of NBS was valid for a δC13value of almost exactly −19 for the NBS preparation in question, it still holds true that all dates given in Stockholm I, II and III can be converted to the new scale by subtracting 55 yr. The NBS preparation St-532 measured by Craig (1961) having a δC13value of −17.2 is only one of several preparations with values between −17 and −20. Age figures are given in C14yr before A.D. 1950; the half life for C14is taken as 5568 ± 30 yr.
University of Michigan Radiocarbon Dates VII
Authors: Crane H. R. , Griffin James B.
Published: July 2016

The following is a list of C14dates obtained since the preparation of the manuscript for publication of Michigan Radiocarbon Dates VI in December 1960. The method of measurement and treatment of data are the same as described in the introduction to Michigan lists III and IV. Since the time of publication of list VI, a full description of the counting technique and equipment has been published (Crane, 1961a, b).
Yale Natural Radiocarbon Measurements VII
Authors: Stuiver Minze , Deevey Edward S.
Published: July 2016

The following list includes many of the measurements made since publication of Yale VI, but many are withheld pending receipt of more complete information or additional samples. We report dates in terms of the Libby half life of C14, 5570 ± 30 yr; geochemical measurements, when normalized for C13content, are given as δ in parts per mil, as described in Yale VI. As before, we acknowledge the technical assistance of George Young, Jonathan King, Sheldon Nankin, and now Carolyn Haupt who has also joined our staff. Our work has been supported by the National Science Foundation, under grants G-19080 to Stuiver and G-19335 to Deevey, and by the U. S. Atomic Energy Commission under contract AT (30–1)–2652.