bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of the Radiocarbon Calibration Program
Authors: Bronk Ramsey Christopher
Published: July 2016

This paper highlights some of the main developments to the radiocarbon calibration program, OxCal. In addition to many cosmetic changes, the latest version of OxCal uses some different algorithms for the treatment of multiple phases. The theoretical framework behind these is discussed and some model calculations demonstrated. Significant changes have also been made to the sampling algorithms used which improve the convergence of the Bayesian analysis. The convergence itself is also reported in a more comprehensive way so that problems can be traced to specific parts of the model. The use of convergence data, and other techniques for testing the implications of particular models, are described.
New Methods and Critical Aspects in Bayesian Mathematics for 14C Calibration
Authors: Steier Peter , Rom Werner , Puchegger Stephan
Published: July 2016

The probabilistic radiocarbon calibration approach, which largely has replaced the intercept method in 14C dating, is based on the so-called Bayes' theorem (Bayes 1763). Besides single-sample calibration, Bayesian mathematics also supplies tools for combining 14C results of many samples with independent archaeological information such as typology or stratigraphy (Buck et al. 1996). However, specific assumptions in the “prior probabilities”, used to transform the archaeological information into mathematical probability distributions, may bias the results (Steier and Rom 2000). A general technique for guarding against such a bias is “sensitivity analysis”, in which a range of possible prior probabilities is tested. Only results that prove robust in this analysis should be used. We demonstrate the impact of this method for an assumed, yet realistic case of stratigraphically ordered samples from the Hallstatt period, i.e. the Early Iron Age in Central Europe.
ΔR Correction Values for the Northern Indian Ocean
Authors: Dutta Koushik , Bhushan Ravi , Somayajulu B L K
Published: July 2016

Apparent marine radiocarbon ages are reported for the northern Indian Ocean region for the pre-nuclear period, based on measurements made in seven mollusk shells collected between 1930 and 1954. The conventional 14C ages of these shells range from 693 ± 44 to 434 ± 51 BP in the Arabian Sea and 511 ± 34 to 408 ± 51 BP in the Bay of Bengal. These ages correspond to mean ΔR correction values of 163 ± 30 yr for the northern Arabian Sea, 11 ± 35 yr for the eastern Bay of Bengal (Andaman Sea) and 32 ± 20 yr for the southern Bay of Bengal. Contrasting reservoir ages for these two basins are most likely due to differences in their thermocline ventilation rates.
Radiocarbon Dates of Old and Middle Kingdom Monuments in Egypt
Authors: Bonani Georges , Haas Herbert , Hawass Zahi , Lehner Mark , Nakhla Shawki , Nolan John , Wenke Robert , Wölfli Willy
Published: July 2016

Between 1984 and 1995 over 450 organic samples were collected from monuments built during the Old and Middle Kingdoms. The most suitable samples were selected for dating. The purpose was to establish a radiocarbon chronology with samples from secure context and collected with the careful techniques required for 14C samples. This chronology is compared to the historical chronology established by reconstructing written documentation.
Quantitative Determination by 14C Analysis of the Biological Component in Fuels
Authors: Dijs Ivo J , van der Windt Eric , Kaihola Lauri , van der Borg Klaas
Published: July 2016

Radiocarbon analysis was performed by liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) to assess whether the content of biological components in hydrocarbon fuels could be derived. Different fuel mixtures were prepared containing bioethanol, fossil ethanol, and fossil gasoline. The specific 14C activity of these mixtures was obtained from LSC measurements and directly related to the concentration of carbon originating from the bioethanol (biocarbon). The results were checked via standardized carbon dating procedures and AMS. A good linear correlation exists between the fuel mixture's specific 14C activity and the concentration of biocarbon. Also, the biocarbon fraction of the fuel mixture (the ratio biocarbon : total carbon) and the normalized fraction of biocarbon (%M) showed good linear correlation. Therefore, both relations provide a possibility to quantitatively determine a fuel's biocarbon content by 14C analysis. When the sample composition is known (e.g. resolved by gas chromatography-mass spectroscopy [GC-MS] and nuclear magnetic resonance [NMR]), the amount of particular biological components in a fuel sample can be derived subsequently. For mixtures of bioethanol, fossil ethanol, and gasoline with bioethanol contents in the range of 0.5–2% m/m, it was found that errors in the normalized fraction of biocarbon (%M) were in the range of 25–10%, respectively. For samples with a higher bioethanol content (up to pure bioethanol), the errors in %M were <10%. Errors might be larger if substantial changes in the concentration of atmospheric 14C took place during the growth period of the biofuel feedstock. By taking into account the variation in specific 14C activity of carbon over the last decades, and by modeling simple tree-growth, it could be illustrated that this effect becomes significant only if the biofuel feedstock stopped growing more than 1 decade ago, e.g. with wood from constructions.
New14C Dates of Neolithic and Early Metal Period Ceramics in Lithuania
Authors: Piličiauskas Gytis , Lavento Mika , Oinonen Markku , Grižas Gytis
Published: July 2016

Twenty-three samples of charred food remains, charcoal, burned animals, and human bones from 14 Lithuanian prehistoric sites were dated by radiocarbon as part of a dating project oriented towards renewing the prehistoric ceramics chronology. The new dates modified the dating of ceramic styles by hundreds to a thousand years. Three Textile Ware sherds were dated to 4230–2920 cal BC—the oldest known dates of Textile Ware pottery in the East Baltic. The organic-tempered pointed-bottomed Narva and Combed-like Wares were dated to 3970–3370 cal BC, while Bay Coast Ware (Haffküstenkultur, Rzucewo), including vessels decorated with cord impressions, were dated to 3940–3540 cal BC, i.e. to a period well preceding the Corded Ware/Battle Axe horizon in Europe. Three dates of Globular Amphorae Ware placed the phenomenon directly beyond the Bay Coast chronology, i.e. in 3450–2920 cal BC. Chamotte-tempered Corded Ware from SE Lithuania was dated to 2840–2570 cal BC. The first absolute dating of coarse ware of the Žalioji type pointed to a period of 760–515 cal BC instead of the previously assumed 2nd millennium cal BC. Cremated human bones from urns found at Paveisininkai, Kernavė, and Naudvaris cemeteries were dated to 790–380 cal BC. Accelerator mass spectrometry (AMS) dates obtained from charred food remains should be treated with a certain caution due to a possible freshwater reservoir effect that has not yet been examined in Lithuania.
Ion Source Development at Kccams, University of California, Irvine
Authors: Southon J R , Santos G M
Published: July 2016

The Keck Carbon Cycle accelerator mass spectrometry facility at the University of California, Irvine, operates a National Electronics Corporation 40-sample MC-SNICS ion source. We describe modifications that have increased beam current output, improved reliability, and made the source easier to service.
Measurement of Low 14C Activities in a Liquid Scintillation Counter in the Zagreb Radiocarbon Laboratory
Authors: Horvatinčić Nada , Barešić Jadranka , Krajcar Bronić Ines , Obelić Bogomil
Published: July 2016

Two methods of chemical preparation of radiocarbon samples are implemented in the Zagreb Radiocarbon Laboratory for measurement by a new liquid scintillation counter (LSC), Quantulus 1220™: a CO2 absorption method (LSC-A) and a benzene synthesis method (LSC-B). For samples prepared by both methods, the optimal counting windows for measurement in LSC were determined. The total efficiency of LSC-A is 65% and that of the LSC-B is 83%, while the corresponding 14C dating limits are 31,800 yr and 52,160 yr, respectively.

14C activities measured by the LSC-A and LSC-B methods were compared with those measured by the gas proportional counter (GPC) method (efficiency 75%, 14C dating limit 37,500 yr). The results obtained by the LSC-A method have larger errors than those measured by the GPC method, but LSC-A is quick, inexpensive, simple, and requires less carbon than the GPC method. Thus, LSC-A is suitable for 14C measurements of geological, hydrological, and environmental samples. On the other hand, the results obtained by the LSC-B method give smaller errors and a larger 14C dating range. Therefore, LSC-B is more suitable for 14C dating of archaeological samples.
Towards Achieving Low Background Levels in Routine Dating by Liquid Scintillation Spectrometry
Authors: Hogg Alan G
Published: July 2016

International radiocarbon intercalibration studies have revealed that radiometric laboratories using liquid scintillation (LS) spectrometry of benzene reported, on average, younger ages for near-background standards than either gas proportional counter (GPC) or accelerator mass spectrometry (AMS) laboratories. These studies suggested that the younger LS ages are probably related to the use of spectrophotometric benzene as a background standard. An analysis of successive 110-ka subfossil wood (Airedale Reef Ancient Wood: ARAW) standards shows that vacuum line memory effects occur in LS spectrometry and, consequently, must be corrected to obtain accurate 14C dates. ARAW standards, measured at monthly intervals in the Waikato laboratory, are used to provide blank corrections for both research and routine dating applications. The strong correlation between the ARAW δ14C data and the sample activities that preceded the standards may provide an opportunity to obtain sample-specific blank corrections. Lithium carbide synthesis is likely to prove a source of contamination. This work suggests that reproducible background levels for routine dating of less than 0.1 pMC (55 ka 14C yr) are achievable.
Extraction and AMS Radiocarbon Dating of Pollen from Lake Baikal Sediments
Authors: Piotrowska Natalia , Bluszcz Andrzej , Demske Dieter , Granoszewski Wojciech , Heumann Georg
Published: July 2016

This work focuses on the preparation and dating of sporomorph (pollen and spores) concentrates of high purity. Three sediment cores recovered from Lake Baikal within the EU-Project CONTINENT were subjected to palynological analyses and accelerator mass spectrometry (AMS) radiocarbon dating. Laboratory processing of concentrates was aimed at the removal of non-sporomorph organic matter by means of chemical treatment, micro-sieving, and heavy liquid separation. The obtained concentrates were checked under the microscope and sample purity was estimated on the basis of particle counts. The results of AMS14C dating show differences in the sedimentation rate among 3 sites of Lake Baikal.
14C Ages of Ostracodes from Pleistocene Lake Sediments of the Western Great Basin, Usa—Results of Progressive Acid Leaching
Authors: Hajdas Irka , Bonani Georges , Herrgesell Zimmerman Susan , Mendelson Millie , Hemming Sidney
Published: July 2016

Progressive dissolution experiments were performed on samples of ostracode shells from lacustrine sediments from the western Great Basin to remove contamination of the surface by secondary calcite. The observed age differences between the external and residual fractions were as great as 2000 to 6000 yr. A “plateau” in ages of the last fractions was obtained only for 1 sample; however, results of repeated experiments resulted in very good agreement of the final ages. A comparison with previously published chronologies based on bulk radiocarbon ages of ostracodes from Wilson Creek (Benson et al. 1990) shows that leaching is imperative for dating samples older than 20 ka B P. This study focuses on the problem of contamination and its removal. However, the final chronology of the Wilson Creek Formation (and other late Pleistocene lacustrine sediments) will require additional dating of other sections as well as establishment of a reservoir effect correction.
Preliminary 14C Dates on Bulk Soil Organic Matter from the Black Creek Megafauna Fossil Site, Rocky River, Kangaroo Island, South Australia
Authors: Forbes Matt , Bestland Erick , Wells Rod
Published: July 2016

Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on Kangaroo Island record 3 phases of deposition and associated soil development which spanned at least the last 20,000 yr. Four new 14C age determinations on bulk soil organic matter and their stratigraphic context are presented in this paper. Three of these age determinations (FP6: 15,687 ± 110 BP [WK11487]; FP7: 16,326 ± 385 BP [WK11488]; and FP8: 17,618 ± 447 BP [WK11489]), are from the organic-rich fossil layer located 45–75 cm below the current floodplain surface. The fourth, a much younger date, FP5: 5589 ± 259 BP (WK11486), was obtained from the base of the overlying modern soil. The dates for the fossil layer increase systematically with depth and correlate well with 5 previous 14C dates (Hope et al., unpublished), ranging between 15,040 ± 120 BP and 19,000 ± 310 BP. This suggests that the data set represents a possible minimum age of the bulk organic matter, and considering the high organic matter contents of approximately 8%, has implications for the age of the megafauna buried in this layer. The overlying modern soil, with its much younger date, contains lower levels of organic matter (3–7%) and gastropods not seen in the fossil layer. This suggests a substantial change in environmental conditions probably due to an alteration in the floodplain drainage conditions. This chronological and sedimentalogical discontinuity indicates that 2 distinct depositional regimes existed and were separated by up to 10,000 14C yr. A calcareous, sandy silt deposit underlying the fossil layer is a calcarenite deposit with low total organic content and is considered the base of the section; it suggests a third separate depositional episode. As such, the Black Creek Swamp in the southwest corner of Kangaroo Island formed intermittently over at least the last 20,000 yr during 3 distinct depositional phases, one of which was the formation of the fossil-laden, organic-rich floodplain surface, which has a possible minimum age of approximately 15,000 to 19,000 BP.
Formation of 13C/12C Isotope Ratios in Speleothems: A Semi-Dynamic Model
Authors: Dulinski Marek , Rozanski Kazimierz
Published: July 2016

A theoretical approach towards predicting the carbon isotope composition of carbonate cave deposits is presented. The proposed model simulates time variations of both the chemical and isotopic composition of the carbonate solution and deposited calcite in the course of CaCO3 precipitation. Two phases of the precipitation process are distinguished and treated separately: initial outgassing of the solution until a certain degree of supersaturation of CO32- ions is reached and subsequent precipitation of CaCO3 related to further outgassing. Precipitation rates of CaCO3 predicted by the model agree fairly well with literature data. The model predicts δ13C values of deposited calcite within a range of ca −16 to +3‰ depending on temperature, chemical and isotope parameters of the initial solution and actual degree of the precipitation process.
A Radiocarbon Chronology for Human-Induced Environmental Change on Mangaia, Southern Cook Islands, Polynesia
Authors: Kirch P. V. , Flenley J. R. , Steadman D. W.
Published: July 2016

A suite of 23 14C age determinations, from a well-stratified rockshelter and from 3 pollen cores on Mangaia Island is reported. The rockshelter has yielded significant evidence for avifaunal extinctions during the period cal. A.D. 1000-1600. The Lake Tiriara pollen cores span a period from ca. 6500 cal. b.p. to the present, and palynological analysis of the TIR 1 core indicates major anthropogenic disturbance on the island's vegetation after ca. 1600 cal. B.P. These sites, and the radiocarbon ages associated with them, provide the first chronologically secure evidence for human impacts on the island ecosystems of the southern Cook Islands.
Ams 14C Age Determinations of Tissue, Bone and Grass Samples from the Ötztal Ice Man
Authors: Bonani Georges , Ivy Susan D. , Hajdas Irena , Niklaus Thomas R. , Suter Martin
Published: July 2016

14C ages of samples from the Ötztal Ice Man, found on the Hauslabjoch in the Tyrolean Alps in September 1991, were determined using accelerator mass spectrometry (AMS). Uncalibrated 14C ages of 4555 ± 34 bp, 4560 ± 65 bp and 4535 ± 60 bp were measured on tissue (mean of four samples), bone and grass, respectively, from the Ice Man. The mean of all of our measurements is 4550 ± 27 bp.
Gliwice Radiocarbon Dates XI
Authors: Pazdur Mieczyslaw F. , Awsiuk Romuald , Goslar Tomasz , Pazdur Anna , Walanus Adam , Zastawny Andrzej
Published: July 2016

The following list presents results of dating archaeological samples from Poland processed between 1979 and 1985. Three carbon dioxide-filled proportional counters (L1, L2 and L3) of different sizes were used for dating (Pazdur et al. 1982). Procedures for sample pretreatment, counting, statistical analysis and age calculations were essentially the same as previously described (Pazdur et al. 1982, 1985). All results are reported as conventional 14C dates in years before ad 1950. Unless explicitly stated, the results are not corrected for isotopic fractionation.
Penguin, A Macintosh Application for Entry and Presentation of Radiocarbon-Dated Samples
Authors: Petri Antonio , Baroni Carlo
Published: July 2016

Penguin is a Macintosh computer application that facilitates the use of CALIB 3.03, the 14C age calibration program by Stuiver and Reimer (1993). Penguin offers an easy user interface based on the well-known Macintosh standard multiwindow environment to create and edit the CALIB 3.03 calibration files and to export data in text format. Penguin and CALIB interact at the file level, i.e., Penguin is capable of reading and writing files in CALIB formats. Files containing the data are created in the Penguin environment and then saved on disk in the Penguin format. Penguin allows multiple editing of the calibration parameters and recalibration of the list of samples without the need to insert any modifications manually throughout the list. Penguin can also be used to read already calibrated files in order to extract the “cal” ages and display them in a spreadsheet-like window.
INGEIS Radiocarbon Laboratory Dates III
Authors: Cordero Roberto , Guida N. G. , Nogueira J. L.
Published: July 2016

The following list presents results of dating of 55 paleoenvironmental and archaeological samples from Argentina, processed between 1984 and 1986 by M. A. Albero and F. Angiolini. Procedures for sample pretreatment, counting, statistical analysis and age calculation were essentially the same as previously described by Albero and Angiolini (1985). Results are reported as conventional 14C dates in years before ad 1950. They are corrected for isotopic fractionation.
Radiocarbon Dating of Total Soil Organic Matter and Humin Fraction and Its Comparison with 14C Ages of Fossil Charcoal
Authors: Pessenda L C R , Gouveia S E M , Aravena R
Published: July 2016

During the last decade radiocarbon dating has been used extensively in distinct regions of Brazil to provide information about soil chronology in paleoenvironmental studies. This paper presents 14C data of soil organic matter (SOM), humin fraction, and charcoal in several soil profiles under natural vegetation from different Brazil locations (north, central, and southeast regions). The main objective is to compare the obtained 14C dating of total SOM with humin, the oldest fraction of SOM. In order to validate the humin ages these data are compared with the age of charcoal collected at similar depths. The 14C ages obtained on charcoal were, in most of the cases, in agreement with the humin fraction considering the experimental errors, or 20% older in average. The dates obtained from total SOM showed significantly younger ages than the humin fraction indicating contamination by younger carbon. These results show the humin fraction is considered a reliable material for 14C dating in soils. However, the humin fraction ages could be assumed as the minimum ages for carbon in soils.
Development of Accurate and Reliable 14C Chronologies for Loess Deposits: Application to the Loess Sequence of Nussloch (Rhine Valley, Germany)
Authors: Hatté Christine , Pessenda Luiz Carlos , Lang Andreas , Paterne Martine
Published: July 2016

Due to very high accumulation rates, loess sequences are best suited archives for the continental paleoclimate of glacial periods. Accurate chronologies cannot be easily established by radiocarbon-dating, because of the lack of organic macrorests, the only material for reliable 14C dating so far. A chemical protocol is reported to extract the organic matter of loess (organic carbon content lower than 0.1% by weight) for accelerator mass spectrometry (AMS) 14C dating. Sediments were taken from the loess sequence of Nussloch, for which a large dataset of luminescence ages (TL, IRSL/OSL) is available. The 14C chronology of the organic matter extracted from loess is in good agreement with the corresponding luminescence ages. It allows high resolution correlations with climatic proxy signals (magnetic susceptibility, malacological assemblages, δ13C on organic matter, etc.) derived from the loess sequence and global environmental proxy records.
Radiocarbon in Seawater Intruding into the Israeli Mediterranean Coastal Aquifer
Authors: Yechieli Y , Sivan O , Lazar B , Vengosh A , Ronen D , Herut B
Published: July 2016

Saline groundwaters from the Israeli coastal aquifer were analyzed for their radiocarbon and tritium content to assess the rate of seawater penetration. The low 14C values (28–88 pMC versus 100–117 pMC in seawater) imply an apparent non-recent seawater source, or water-rock interactions along the penetration route. The latter process is supported by measurable tritium values at some locations, which imply a relatively rapid rate of seawater intrusion. In other locations, low tritium values (<2 T.U.) indicate that recent seawater (<50 yr) did not penetrate inland. The low δ13C values in saline groundwater (average of −5.3‰ versus 0‰ in seawater) indicate that the dissolved carbon pool is comprised of a significant fraction of organic carbon. A linear negative correlation between δ13C and 14C implies that this organic source is old (low 14C values).
Influence of the Bomb-Produced 14C on the Radiocarbon Concentration in the Youngest Sediments of Lake Gościąż, Central Poland
Authors: Pawlyta Jacek , Pazdur Anna , Goslar Tomasz , Hałas Stanisław
Published: July 2016

This work is a study of changes of the radiocarbon concentration in the youngest part of Lake Gościąż sediments in the calendar time scale during the last 150 years. This period includes the time of the nuclear weapons tests performed in the upper atmosphere in the 1950s and the 1960s, which caused large release of 14C and 137Cs into the environment. On the basis of this study, the isotope dilution factor for 14C and the exchange time of carbon between the atmosphere and Lake Gościąż was estimated. The chronology of the upper part of the sediments was constructed using many interdisciplinary investigations. Among them, measurements of 137Cs in the sediment were used. An unexpected discrepancy between the previously constructed time scale and that suggested by 137Cs is observed in one of the cases.
A Time History of Pre- and Post-Bomb Radiocarbon in the Barents Sea Derived from Arcto-Norwegian Cod Otoliths
Authors: Kalish John M , Nydal Reidar , Nedreaas Kjell H , Burr George S , Eine Gro L
Published: July 2016

Radiocarbon measured in seawater dissolved inorganic carbon (DIC) can be used to investigate ocean circulation, atmosphere/ocean carbon flux, and provide powerful constraints for the fine-tuning of general circulation models (GCMs). Time series of 14C in seawater are derived most frequently from annual bands of hermatypic corals. However, this proxy is unavailable in temperate and polar oceans. Fish otoliths, calcium carbonate auditory, and gravity receptors in the membranous labyrinths of teleost fishes, can act as proxies for 14C in most oceans and at most depths. Arcto-Norwegian cod otoliths are suited to this application due to the well-defined distribution of this species in the Barents Sea, the ability to determine ages of individual Arcto-Norwegian cod with a high level of accuracy, and the availability of archived otoliths collected for fisheries research over the past 60 years. Using measurements of 14C derived from Arcto-Norwegian cod otoliths, we present the first pre- and post-bomb time series (1919–1992) of 14C from polar seas and consider the significance of these data in relation to ocean circulation and atmosphere/ocean flux of 14C. The data provide evidence for a minor Suess effect of only 0.2‰ per year between 1919 and 1950. Bomb 14C was evident in the Barents Sea as early as 1957 and the highest 14C value was measured in an otolith core from a cod with a birth date of 1967. The otolith 14C data display key features common to records of 14C obtained from a Georges Bank mollusc and corals from the tropical and subtropical North Atlantic.
32Si Dating of Marine Sediments from Bangladesh
Authors: Morgenstern U , Geyh M A , Kudrass H R , Ditchburn R G , Graham I J
Published: July 2016

Appropriate dating tools are essential for paleoenvironmental studies. Cosmogenic 32Si with a half-life of about 140 years is ideally suited to cover the dating range 30–1000 years. Here we have applied scintillation spectrometry for detection of natural 32Si to date marine shelf sediments. High detection efficiency, combined with stable background, allows for the detection of extremely low 32Si specific activities found in such sediments with counting rates below one count per hour. For a sediment core from the Ganges-Brahmaputra delta 32Si dating yields mean sedimentation rates of 0.7 ± 0.2 cm/yr for 50 to several hundred years BP and 3.1 ± 0.8 cm/yr for the past 50 years. The four-fold increase of the sedimentation rate over the past 50 years may reflect increased sediment loads in the rivers due to increasing human colonization within the rivers' drainage basins.
Quantitative Extraction of Dissolved Inorganic Carbon (as CO2) and Water by Vacuum Distillation from Sediments of the Unsaturated Zone for Carbon Isotope Analysis (13C and 14C)
Authors: Carmi I , Kronfeld J , Yechieli Y , Yakir D , Stiller M , Boaretto E
Published: July 2016

Vacuum distillation is shown to be useful for the quantitative extraction of dissolved inorganic carbon (as CO2) and water from sediments of the unsaturated zone in the Coastal Aquifer of Israel. Several tests of vacuum extractions from tap water and sediments are presented, including standard addition, which show that the distillation procedure is quantitative, with minimal or no carbon isotope fractionation. The optimal temperature of the sediment during the extraction was also defined. Examples of vacuum extractions of sediments are shown.
First Lapita Settlement and its Chronology in Vava'u, Kingdom of Tonga
Authors: Burley David V , Connaughton Sean P
Published: July 2016

Beginning approximately cal 1400 BC, Austronesian-speaking Lapita peoples began a colonizing migration across Oceania from the Bismarck Archipelago to western Polynesia. The first point of entry into Polynesia occurred on the island of Tongatapu in Tonga with subsequent spread northward to Samoa along a natural sailing corridor. Radiocarbon measurements from recent excavations at 4 sites in the northern Vava'u islands of Tonga provide a chronology for the final stage of this diaspora. These dates indicate that the northern expansion was almost immediate, that a paucity of Lapita sites to the north cannot be explained as a result of lag time in the settlement process, and that decorated Lapita ceramics disappeared rapidly after first landfalls.
Background Concentration of 14C in Aquatic Samples from Brackish Lake Obuchi, Rokkasho, Japan, Adjacent to Nuclear Fuel Reprocessing Facilities
Authors: Ueda Shinji , Kondo Kunio , Inaba Jiro
Published: July 2016

The brackish Lake Obuchi in Rokkasho, Japan, is adjacent to the first Japanese commercial nuclear fuel reprocessing facilities, which are now undergoing performance testing, with commercial operation scheduled to start in 2007. Preparatory surveys were made by measuring the background levels of radiocarbon for water, aquatic biota, and sediment samples using accelerator mass spectrometry (AMS) in order to study the potential effects of 14C released by the plant to the 14C concentration in aquatic samples. Concentrations of 14C in Futamata River in 2004 ranged from 102 ± 0.5 to 109 ± 0.6 pMC (average 106 ± 0.6 pMC), while 14C concentrations in brackish water from Lake Obuchi and in seawater were 89 ± 0.5 to 104 ± 0.4 pMC (average 98 ± 0.5 pMC) and 82 ± 0.6 to 102 ± 0.4 pMC (average 93 ± 0.5 pMC), respectively. The relationship between 14C concentration and salinity showed a negative correlation (r = 0.68, P < 0.01, n = 20). 14C concentration in selected aquatic biota (i.e. fish, benthos, and seagrass) from 2003 to 2004 ranged from 105 ± 0.7 to 107 ± 0.6 pMC and in zooplankton and phytoplankton was 103 ± 2.4 to 105 ± 1.7 pMC. The depth profile of 14C in 3 core sediment samples from Lake Obuchi showed maximum concentrations from 103 ± 0.5 to 106 ± 0.5 pMC at 5–20 cm depth. The vertical profile of 14C concentration in the sediment did not follow global atmospheric 14C fallout. We confirmed that the background level of 14C concentration in aquatic samples in brackish Lake Obuchi before operation of the reprocessing plant was similar to the concentration (∼106 pMC) in the recent atmosphere.
A Preliminary Determination of the Absolute 14C/12C Ratio of OX-I
Authors: Roberts M L , Southon J R
Published: July 2016

A preliminary determination of the absolute 14C/12C ratio of the oxalic acid I standard (NBS SRM 4990B) has been made. Using an accelerator mass spectrometry (AMS) system, a known number of radiocarbon ions were implanted in a thin copper foil. The foil was then combusted with the addition of 14C-free carrier material. This resulting gas (which had a known 14C/12C ratio) was graphitized and compared to OX-I material. This comparison yielded an absolute 14C/12C ratio of OX-I. The absolute 14C/12C ratio of OX-I, coupled with knowledge of the specific activity of OX-1, provides an alternative determination of the 14C half-life.
HBCO Correction: Its Impact on Archaeological Absolute Dating
Authors: Barta Peter , Štolc Svorad
Published: July 2016

When constructing absolute chronologies in archaeology, the aim is to detect archaeological events. In this respect, we draw attention to the relation between the radiocarbon ages of human bone collagen samples and the absolute dating evidence on the age at death. In recent material, Mebus Geyh (2001a,b) described the offset between the former and the latter, and suggested the relevant correction. The corrected 14C ages pertain to the age of the individual at death.

We have developed an application of Geyh's original observation, which we term the human bone collagen offset (HBCO) correction, to apply to archaeological 14C dates. If the death and interment of individuals are identical, the corrected 14C date reliably informs us about the deposition of the body and accompanying grave goods. In archaeology, the concrete correction value is determined by the anthropologically estimated age of the individual, which we model by a normal (Gaussian) distribution. The eventual impact of the HBCO correction on archaeological chronology depends on the portion of the calibration curve through which the HBCO-corrected date is calibrated. At a certain level of 14C measurement precision, the difference between the HBCO-corrected and non-corrected calendar dates can be considerable.
Radiocarbon in 9th to 5th Century BC Tree-Ring Samples from the Ouban 1 Archaeological Site, Hiroshima, Japan
Authors: Ozaki Hiromasa , Imamura Mineo , Matsuzaki Hiroyuki , Mitsutani Takumi
Published: July 2016

In order to investigate the regional atmospheric radiocarbon offset, accelerator mass spectrometry (AMS) 14C measurements were made on 5-yr increments of a Japanese wood sample dendrochronologically dated to 820–436 BC. The 14C data from the Japanese tree-ring samples were compared with the IntCal04 calibration curve (Reimer et al. 2004). In most parts, the differences between IntCal04 and 14C dates in the Japanese tree-ring samples were within experimental statistical errors. At around 680 BC, however, significant differences of up to 100 14C yr were observed. These differences may indicate either regional offsets in Japan or the short-term fluctuation of a subdecadal timescale in atmospheric 14C variations.
Evolution of Waterways and Early Human Settlements in the Eastern Baltic Area: Radiocarbon-Based Chronology
Authors: Dolukhanov P M , Shukurov A M , Arslanov Kh A , Subetto D A , Zaitseva G I , Djinoridze E N , Kuznetsov D D , Ludikova A V , Sapelko T V , Savelieva L A
Published: July 2016

Newly obtained radiocarbon measurements are used to suggest that the initial settlement of the northeastern Baltic area was largely controlled by the Ladoga-Baltic waterway in the north of the Karelian Isthmus, which emerged ∼11,500 cal BP and remained in action for ∼7000 yr. The transgression of Ladoga Lake started ∼5000 cal BP and reached its maximum at ∼3000 cal BP (∼1100–1000 cal BC). The formation of a new outlet via the Neva River led to a rapid regression of the lake that stimulated the spread of farming populations.
The End of Empire: New Radiocarbon Dates from the Ayacucho Valley, Peru, and their Implications for the Collapse of the Wari State
Authors: Finucane Brian Clifton , Valdez J Ernesto , Calderon Ismael Pérez , Pomacanchari Cirilo Vivanco , Valdez Lidio M , O'Connell Tamsin
Published: July 2016

This paper presents a suite of new accelerator mass spectrometry (AMS) radiocarbon measurements from the Ayacucho Valley of Peru and discusses their implications for the timing and nature of the collapse of the Wari Empire. Analysis of these and previously published dates from the region indicate that there is little evidence for state political authority in Ayacucho prior to the end of the 7th century. Dated human remains from the polity's eponymous capital indicate that the authority of the state's rulers persisted at least as late as the mid-11th century. Dates from rural sites in the Ayacucho Valley suggest continuity of occupation and folk material culture following Wari's disintegration. Finally, AMS measurements of bone from 2 large extramural ossuaries represent the first absolute dates associated with Chanca ceramics and suggest that this archaeological/ethnohistoric culture appeared in the valley at about AD 1300.
Floating Larch Tree-Ring Chronologies from Archaeological Timbers in the Russian Altai Between about 800 BC and AD 800
Authors: Panyushkina Irina , Sljusarenko Igor , Bikov Nikolay , Bogdanov Eugene
Published: July 2016

We obtained over 200 archaeological wood specimens from the southeastern part of the Altai Mountains (Russia) to establish accurate calendar dates of the timbers using both radiocarbon and tree-ring analyses. Most timbers came from small and elite tombs of the Pazyryk culture (Siberian Scythians of the Iron Age period). Timbers from Hun-Sarmatian and Turk times (1st millennium AD) were studied for the first time. Three floating tree-ring width chronologies of larch (Larix sibirica) with lengths of 486 yr to 144 yr were developed from the tree-ring data. Tree rings of the composite 486-yr chronology of the Pazyryk culture represent the regional scale of Altai tree-ring width variability between about 720–240 BC. The composite chronology dates the earliest construction of Pazyryk culture tombs to ∼320 BC (ordinary tombs) and the latest ones at 240 BC (Pazyryk noble tomb #5). The composite chronology might be used for tree-ring dating wood from Scythian tombs in the region. It will also help confirm the precision of 14C dating of the Scythian tombs around the Hallstatt plateau of 14C calibration curves. We developed a 110-yr decadal 14C sequence from the Kurayka site that dates Kok-Pash culture timbers back to cal AD 240 (Hun-Sarmatian period). 14C dates of wooden poles from 3 sites of Turk stone enclosures suggested wood cutting dates between cal AD 470 and 830. The results demonstrate that crossdating tree rings along with 14C dating of crossdated rings provide the most reliable and highest precision dates for these archaeological sites.
Radiocarbon “Wiggles” in Great Lakes Wood at About 10,000 to 12,000 BP
Authors: Leavitt Steven W , Panyushkina Irina P , Lange Todd , Cheng Li , Schneider Allan F , Hughes John
Published: July 2016

High-resolution radiocarbon calibration for the last 14,000 cal yr has been developed in large part using European oaks and pines. Recent subfossil wood collections from the Great Lakes region provide an opportunity to measure 14C activity in decadal series of rings in North America prior to the White Mountains bristlecone record. We developed decadal 14C series from wood at the classic Two Creeks site (∼11,850 BP) in east-central Wisconsin, the Liverpool East site (∼10,250 BP) in northwestern Indiana, and the Gribben Basin site (∼10,000 BP) in the Upper Peninsula of Michigan. Initial AMS dates on holocellulose produced younger-than-expected ages for most Two Creeks subsamples and for a few samples from the other sites, prompting a systematic comparison of chemical pretreatment using 2 samples from each site, and employing holocellulose, AAA-treated holocellulose, alpha-cellulose, and AAA-treated whole wood. The testing could not definitively reveal the source of error in the original analyses, but the “best” original ages together with new AAA-treated holocellulose and α-cellulose ages were visually fitted to the IntCal04 calibration curve at ages of 13,760–13,530 cal BP for the Two Creeks wood, 12,100–12,020 cal BP for Liverpool East, and 11,300–11,170 cal BP for Gribben Basin. The Liverpool East age falls squarely within the Younger Dryas (YD) period, whereas the Gribben Basin age appears to postdate the YD by ∼300 yr, although high scatter in the decadal Gribben Basin results could accommodate an older age nearer the end of the YD.
Is There a Time-Transgressive Holocene Optimum in the East Asian Monsoon Area?
Authors: Zhou Weijian , Song Shaohua , Burr G , Jull A J T , Lu Xuefeng , Yu Huagui , Cheng Peng
Published: July 2016

We have carried out a multiproxy analysis of high-resolution eutrophic peat/mud, sand dune, and loess/paleosol sequences covering the Holocene period in both southern and northern China, in order to test the hypothesis of a time-transgressive Holocene optimum in the East Asian monsoon area (An et al. 2000). Samples were radiocarbon dated to establish the chronology. Our results indicate that the Holocene optimum occurred between ∼10,000–5000 cal yr ago in both southern and northern China, consistent with a global pattern rather than simply a local expression. Our data also support the conclusion that the evolution of Holocene climate in China is consistent with changes in Northern Hemisphere solar radiation.
Circulation in the Northern Japan Sea Studied Chiefly with Radiocarbon
Authors: Aramaki T , Senjyu T , Togawa O , Otosaka S , Suzuki T , Kitamura T , Amano H , Volkov Y N
Published: July 2016

Radiocarbon concentrations in the northernmost region of the Japan Sea were observed during the summer of 2002. The averaged surface δ14C (above 100 m depth) was 52 ± 8%, which is significantly higher compared with the values of the Pacific Ocean and Okhotsk Sea. The δ14C in the deep water decreased with density, and the minimum value was −70%. By analyzing 14C and other hydrographic data, we found that i) the Tsushima Warm Current Water reaches to the surface layer in the southern Tatarskiy Strait; ii) deep convection did not occur in the northernmost region, at least not after the winter of 2001–2002; and iii) the bottom water that was previously formed in this region may step down southward along the bottom slope and mix with the Japan Sea Bottom Water. Furthermore, a new water mass characterized by high salinity (>34.09 psu) was found in the subsurface layer in the area north of 46°N.
The Feasibility of Using Melanopsis Shells as Radiocarbon Chronometers, Lake Kinneret, Israel
Authors: Lev Lilach , Boaretto Elisabetta , Heller Joseph , Marco Shmuel , Stein Mordechai
Published: July 2016

We investigated the feasibility of using Melanopsis shells as radiocarbon chronometers of paleolakes and springs in the Jordan Valley, Israel. For this purpose, we analyzed the 14C content of aragonite of living Melanopsis shells from different freshwater bodies of the northern Jordan Valley and Lake Kinneret (Sea of Galilee) and compared them to the contemporaneous water values. The Melanopsis shells are in 14C equilibrium with their habitat waters, allowing to specify a particular reservoir age for various water types. We measured ∼750 yr for Lake Kinneret, ∼2300 yr for northern Jordan, ∼4600 yr for springs in the north Kinneret, and ∼7200 yr for streams flowing directly from carbonate aquifers. These results were tested and corroborated by analyzing fossil Melanopsis shells of known age, measured on contemporaneous organic matter. We conclude that Melanopsis shells are reliable 14C chronometers and have the potential to be used as paleohydrological tracers.
Radiocarbon Dating of Large Holocene Volcanic Events Within South Kamchatka (Russian Far East)
Authors: Zaretskaya Natalia E , Ponomareva Vera V , Sulerzhitsky Leopold D
Published: July 2016

Radiocarbon dating is widely used when studying recent volcanic activity in the Kamchatka Peninsula due to the abundance of organic matter that is associated with the volcanic deposits. Here, we present the results of 14C dating of major volcanic events within the active South Kamchatka volcanic zone. South Kamchatka includes 8 recently active volcanic centers (stratovolcanoes, calderas, and large craters) that have been erupting during the Holocene. Their tephras represent useful markers for both the southern part of the peninsula and the Northern Kurile Islands. Since these marker tephra layers facilitate stratigraphic and tephrochronological studies in this area, it was important to determine their ages. We have obtained 73 new individual 14C dates on paleosol, peat, charcoal, and wood associated with the marker tephra layers, then complemented these data with 37 earlier published dates and analyzed the resulting data set. We selected the reliable dates and then obtained average 14C ages of marker tephra layers. The details of these procedures, as well as brief descriptions of South Kamchatka Holocene eruptions and their tephra beds, are presented in the paper.
New Evidence from the East Polynesian Gateway: Substantive and Methodological Results from Aitutaki, Southern Cook Islands
Authors: Allen Melinda S , Wallace Rod
Published: July 2016

East Polynesia was the geographic terminus of prehistoric human expansion across the globe and the southern Cook Islands, the first archipelago west of Samoa, a gateway to this region. Fourteen new radiocarbon dates from one of the oldest human settlements in this archipelago, the Ureia site (AIT-10) on Aitutaki Island, now indicate occupation from cal AD 1225–1430 (1σ), nearly 300 yr later than previously suggested. Although now among the most securely dated central East Polynesian sites, the new age estimate for Ureia places it outside the settlement period of either the long or short chronology models. The new dates have, however, led to a comfortable fit with the Ureia biological evidence, which suggests not a virgin landscape, but a highly a modified fauna and flora. The results also provide the first systematic demonstration of inbuilt age in tropical Pacific trees, a finding that may explain widely divergent 14C results from several early East Polynesian sites and has implications for the dating of both island colonization and subsequent intra-island dispersals.
New Accelerator Mass Spectrometry (AMS) Ages Suggest a Revision of the Electron Spin Resonance (ESR) Middle Holocene Dates Obtained for a Toxodon platensis (Toxodontidae, Mammalia) from Southeast Brazil
Authors: Neves Walter , Hubbe Alex , Karmann Ivo
Published: July 2016

In a paper published in Applied Radiation and Isotopes, Baffa et al. (2000) reported a Middle Holocene date (∼6.5 kyr BP) for a specimen of Toxodon platensis from Ribeira do Iguape, southeast Brazil, using the emergent technique electron spin resonance (ESR). Through an accelerator mass spectrometry (AMS) procedure applied on tooth collagen, we provide a new set of dates to test the accuracy of the ages generated by ESR. We obtained 2 dates more than 4500 BP older than the previous one, suggesting a minimum Late Pleistocene age for the specimen.
Estimated Reservoir Ages of the Black Sea Since the Last Glacial
Authors: Kwiecien O , Arz H W , Lamy F , Wulf S , Bahr A , Röhl U , Haug G H
Published: July 2016

Accelerator mass spectrometry (AMS) radiocarbon dating of ostracod and gastropod shells from the southwestern Black Sea cores combined with tephrochronology provides the basis for studying reservoir age changes in the late-glacial Black Sea. The comparison of our data with records from the northwestern Black Sea shows that an apparent reservoir age of ∼145014C yr found in the glacial is characteristic of a homogenized water column. This apparent reservoir age is most likely due to the hardwater effect. Though data indicate that a reservoir age of ∼145014C yr may have persisted until the Bølling-Allerød warm period, a comparison with the GISP2 ice-core record suggests a gradual reduction of the reservoir age to ∼100014C yr, which might have been caused by dilution effects of inflowing meltwater. During the Bølling-Allerød warm period, soil development and increased vegetation cover in the catchment area of the Black Sea could have hampered erosion of carbonate bedrock, and hence diminished contamination by “old” carbon brought to the Black Sea basin by rivers. A further reduction of the reservoir age most probably occurred contemporary to the precipitation of inorganic carbonates triggered by increased phytoplankton activity, and was confined to the upper water column. Intensified deep water formation subsequently enhanced the mixing/convection and renewal of intermediate water. During the Younger Dryas, the age of the upper water column was close to 0 yr, while the intermediate water was ∼90014C yr older. The first inflow of saline Mediterranean water, at ∼830014C yr BP, shifted the surface water age towards the recent value of ∼40014C yr.
British Museum Natural Radiocarbon Measurements XIX
Authors: Ambers Janet , Burleigh Richard , Matthews Keith
Published: July 2016

The following list consists of dates for archaeologic samples mostly measured from June 1984 to June 1985. The dates were obtained by liquid scintillation counting of benzene using the laboratory procedures outlined in previous lists (see, eg, BM-VIII, R, 1976, v 18, p 16). Dates are expressed as suggested by Stuiver and Polach (1977),ie, in14C years relative to AD 1950, based on the Libby half-life for14C of 5570 yr, and corrected for isotopic fractionation (δ13C values are given relative to PDB). No corrections have been made for natural14C variations. The modern reference standards are the NBS oxalic acids (SRM 4990 and RM 49). Errors quoted are the counting error for the sample, combined with an estimate of the errors contributed by the modern and background samples. This estimate includes both counting and non-counting errors, and is computed from differences in the overall count rates observed among the individual backgrounds and moderns. The overall error is given as ± 1 standard deviation (± 1σ). Descriptions, comments, and references to publications are based on information supplied by submitters.