bluuebunny/crossref_metadata_2025 huggingface dataset:
Applications of Radiocarbon Dating Method
Authors: Hajdas Irka
Published: July 2016

The main force driving technical development of the radiocarbon dating technique is the wide spectrum of applications that cross interdisciplinary boundaries of Earth and social sciences. This paper provides a very brief overview of some of the many applications of14C analysis to various studies of human origin and migration, cultures and history, past and present environment, and the human body itself.
Development of Radiocarbon Dating in China Over the Past 50 Years
Authors: Zhou Weijian , Chen Maobai
Published: July 2016

On the arrival of the 50th anniversary of Radiocarbon, we review important developments in radiocarbon dating in China during the past 50 years, especially concerning 3 aspects: sample standard and preparation, accelerator mass spectrometry (AMS) facilities, and 14C applications. Specifically, these events are marked by the establishment of the Chinese sucrose charcoal standard in China; the development of small-sample dating in the Xi'an Laboratory of Loess and Quaternary Geology, Chinese Academy of Sciences (CAS); the progress of the AMS facilities in Beijing (China Institute of Atomic Energy and Beijing University); the innovation of the mini-cyclotron-based AMS at Shanghai Institute of Nuclear Research, CAS; the exploration of the Xia-Shang-Zhou chronology project in China; the establishment of the Xi'an multi-element AMS at the Xi'an-AMS Center; and the breakthrough in tracing the geomagnetic intensities and precipitation from 10Be in Chinese loess at the Institute of Earth Environment, CAS.
Dating Materials in Good Archaeological Contexts: The Next Challenge for Radiocarbon Analysis
Authors: Boaretto Elisabetta
Published: July 2016

Radiocarbon dating has had an enormous impact on archaeology. Most of the dates are obtained using charred materials and, to a lesser extent, collagen from bones. The contexts in which charred materials and bones are found are often, however, not secure. There are 3 other datable materials that are usually in secure contexts: plaster/mortar, phytoliths, and the organic material in the ceramic of whole vessels. The plaster/mortar of walls and floors are often in very secure contexts. Phytoliths are abundant in archaeological sites and in some situations form well-defined surfaces. Whole vessels are usually found in secure contexts and their typologies are indicative of a specific period. Dating each of these materials has proved to be difficult, and solving these technical problems represents major future challenges for the14C community. The effective use of charcoal and bone collagen for dating can also be improved by paying careful attention to the micro-contexts in which they are found, such as in clusters or as part of well-defined features. Pre-screening to identify the best preserved material can also contribute to improving the accuracy of the dates obtained. A general objective should be to have an assessment of the quality of the material to be dated so that the potentially invaluable information from outliers can be exploited.
Calibration Commentary
Authors: Blockley S P E , Housley R A
Published: July 2016

Radiocarbon is by far and away the most widely used dating tool in the Late Quaternary. Hundreds of key papers rely on the method to provide absolute and relative chronological information on important topics, including the late evolution of our own species (e.g. Higham et al. 2006a) and the timing and nature of abrupt climatic changes during the last glaciation (Lowe et al. 2001). Calibration of 14C determinations is an essential part of the dating process, and the implications of calibration can lead to significant differences in the interpretation of important processes (Blockley et al. 2006). Any development that enhances the accuracy, precision, or time coverage of the calibration curves is therefore to be welcomed. Since the early 1980s, there has been periodic publication of carefully vetted data in the form of internationally recognized consensus calibration curves that have allowed 14C users to convert their raw 14C determinations into calendar ages (Klein et al. 1982; Stuiver and Reimer 1986, 1993; Stuiver et al. 1998; Reimer et al. 2004). In the beginning, the basis on which this was done was easy to understand, 14C measurements were made on tree rings and the absolute calendar age came from counting annual growth rings. Although not without its complexities, the terrestrial tree-ring approach remains the most certain method and is at the heart of calibration process in the period 0–12.4 cal kyr. However, for periods beyond the limit of the tree-ring sequences the situation was significantly more problematic, and at times, even controversial.
The Beginning of the Early Bronze Age in the North Jordan Valley: New14C Determinations from Pella in Jordan
Authors: Bourke Stephen , Zoppi Ugo , Meadows John , Hua Quan , Gibbins Samantha
Published: July 2016

This article reports on 10 new accelerator mass spectrometry (AMS) radiocarbon dates from early phases of the Early Bronze Age at the long-lived settlement of Pella (modern Tabaqat Fahl) in the north Jordan Valley. The new AMS dates fall between 3400 and 2800 cal BC, and support a recent suggestion that all Chalcolithic period occupation had ceased by 3800/3700 cal BC at the latest (Bourke et al. 2004b). Other recently published Early Bronze Age14C data strongly supports this revisionist scenario, suggesting that the earliest phase of the Early Bronze Age (EBA I) occupied much of the 4th millennium cal BC (3800/3700 to 3100/3000 cal BC). As this EB I period in the Jordan Valley is generally viewed as the key precursor phase in the development of urbanism (Joffe 1993), this revisionist chronology has potentially radical significance for understanding both the nature and speed of the move from village settlement towards a complex urban lifeway.
Radiocarbon Concentrations of Wood Ash Calcite: Potential for Dating
Authors: Regev Lior , Eckmeier Eileen , Mintz Eugenia , Weiner Steve , Boaretto Elisabetta
Published: July 2016

Ash is formed when plant calcium oxalate crystals (CaC2O4) decompose to form calcite (CaCO3). We found that ash does retain the original calcium oxalate radiocarbon concentration, but in addition, there is another minor 14C source. This is shown by the presence of a consistent small shift in the pMC and δ13C levels when comparing cellulose and ash from modern and archaeological woods. Possible mechanisms for 14C exchange during combustion or due to diagenesis are considered in order to define parameters for identifying better-preserved wood ash samples.
IFAN Radiocarbon Laboratory Measurements I
Authors: Ndeye Maurice , Sène Matar , Oumar Diallo Alpha
Published: July 2016

Results obtained from a liquid scintillation counter using BGO (Bi4Ge3012) tubes have produced more precise radiocarbon dates in our laboratory. Duplicate analyses confirm the electronic stability of the counter with a background of 0.1 cpm. Our 14C dates agree well with those from another laboratory (Paris 6-LOCEAN). Most of the 14C dates in this study were obtained on samples taken from different archaeological sites. Calibration of the various dates with the appropriate software (CALIB 5.0 in our case) allows better interpretation of the results and their importance in this understudied region. In this paper, we investigate the performance of the counter by analyzing samples from archaeological and marine sites in Senegal and Mauritania, and report the results in our first laboratory date list.
New Radiocarbon Dates for the Grenadine Islands (West Indies)
Authors: Fitzpatrick Scott M , Giovas Christina M
Published: July 2016

Intensified archaeological research in the Caribbean over the past 2 decades has provided a wealth of new information on how and when these islands were settled prehistorically. However, there has been a paucity of research on islands in the southern Lesser Antilles, which would allow for more rigorous testing of migration models and various settlement pattern hypotheses. To address some of these chronological and geographical gaps, we present a corpus of 41 radiocarbon dates from several sites in the Grenadine Island chain. Results to date support a relatively late Ceramic Age settlement of these smaller islands (about AD 400) compared to other nearby, larger islands in the southern Lesser Antilles (about AD 200) as well as the Caribbean as a whole (about 400/500 BC). Intriguing questions also remain as to an apparent, but as yet inadequately tested, pattern where earlier colonization dates are correlated with larger island size.
Systematic14C Dating of a Unique Early and Middle Bronze Age Cemetery at Xeropigado Koiladas, West Macedonia, Greece
Authors: Maniatis Y , Ziota Ch
Published: July 2016

Systematic radiocarbon dating was performed on a unique EBA-MBA cemetery at Xeropigado Koiladas situated at the edge of the Kitrini Limni basin in the Kozani area, northwest Greece. It was found that this cemetery had a particularly long period of use of ~700 yr (between about 2420 and 1730 BC), which is especially pronounced if compared with the relatively small number of burials totaling 222. The dating revealed no spatial differentiation with time; the entire area of the cemetery was used throughout the time. There is a tendency of the dates to concentrate mostly in the time ranges 2200–2030 and 2000–1850 BC, which may tentatively suggest a more intense use of the cemetery during these periods. The results from multiple or consequent burials revealed that this cemetery was a landmark visible to the people of that time for at least 500 yr, if not for the entire period of its use. Some of the graves were built on top of, or adjacent to, older ones without disturbing the old burials. This implies that the Xeropigado cemetery was an important place of reference for at least 25 generations! No settlements have been found yet in the area that could be associated with the Xeropigado cemetery. Some synchronizations with various other sites in west Macedonia, for which14C dates are available, are presented.
Influence of Mollusk Species on Marine ΔR Determinations
Authors: Ascough Philippa L , Cook Gordon T , Dugmore Andrew J , Scott E Marian , Freeman Stewart P H T
Published: July 2016

Radiocarbon ages were measured on replicate samples of burnt grain and 5 mollusk species collected from a single sealed layer at an archaeological site (Hornish Point) on the west coast of South Uist, Scotland. The aim was to examine the impact of using different mollusk species on ΔR determinations that are calculated using the paired terrestrial/marine sample approach. The mollusk species examined inhabit a range of environments and utilize a variety of food sources within the intertidal zone. Several authors have suggested that these factors may be responsible for observed variations in the14C activity of mollusk shells that were contemporaneous in a single location. This study found no significant variation in the14C ages of the mollusk species, and consequently, no significant variation in calculated values of ΔR. The implication is that in an area where there are no carboniferous rocks or significant local inputs of freshwater to the surface ocean, any of a range of marine mollusk species can be used in combination with short-lived terrestrial material from the same secure archaeological context to accurately determine a ΔR value for a particular geographic location and period in time.
Paleogroundwater in the Moutere Gravel Aquifers Near Nelson, New Zealand
Authors: Stewart Michael K , Thomas Joseph T , Norris Margaret , Trompetter Vanessa
Published: July 2016

Radiocarbon, 18O, and chemical concentrations have been used to identify groundwater recharged during the last ice age near Nelson, New Zealand. Moutere Gravel underlies most of the Moutere Depression, a 30-km-wide system of valleys filled with Plio-Pleistocene gravel. The depression extends northwards into Tasman Bay, which was above sea level when the North and South Islands of New Zealand were connected during the last glaciation. The aquifers are tapped by bores up to 500 m deep. Shallow bores (50–100 m) tap “pre-industrial” Holocene water (termed the “modern” component) with 14C concentrations of 90 ± 10 percent modern carbon (pMC) and δ18O values of −6.8 ± 0.4, as expected for present-day precipitation. Deeper bores discharge water with lower 14C concentrations and more negative 18O values resulting from input of much older water from depth. The deep end-member of the mixing trend is identified as paleowater (termed the “glacial” component) with 14C concentration close to 0 pMC and more negative 18O values (-7.6). Mixing of the modern and glacial components gives rise to the variations observed in the 14C, 18O, and chemical concentrations of the waters. Identification of the deep groundwater as glacial water suggests that there may be a large body of such water onshore and offshore at deep levels. More generally, the influence of changing sea levels in the recent past (geologically speaking) on the disposition of groundwaters in coastal areas of New Zealand may have been far greater than we have previously realized.
Radiocarbon Ages and Isotope Fractionations of Beachrock Samples Collected from the Nansei Islands, Southwestern Japan
Authors: Omoto Kunio
Published: July 2016

A total of 294 beachrock samples were collected from 116 sites on 15 islands in the Nansei Islands chain, southwestern Japan, and were radiocarbon dated. The beachrocks began to form at about 6900 BP and some are still under development in the islands. Values of isotope fractionations of different materials making up the beachrocks ranged between +9.4‰ and −5.7‰. Isotope fractionations outside the range of 0 ± 2‰ suggest that these beachrocks were strongly influenced by underground water and running freshwater when they were cemented. The sea level during the late Holocene has remained the same for at least the past 5000 yr, except for several uplifted coasts.
Holocene Variations in the Scottish Marine Radiocarbon Reservoir Effect
Authors: Ascough Philippa L , Cook Gordon T , Dugmore Andrew J , Barber John , Higney Elaine , Marian Scott E
Published: July 2016

We assessed the evidence for variations in the marine radiocarbon reservoir effect (MRE) at coastal, archaeological Iron Age sites in north and west Scotland by comparing AMS measurements of paired marine and terrestrial materials (4 pairs per context). ΔR values were calculated from measurements on material from 3 sites using 6 sets of samples, all of which were deposited around 2000 BP. The weighted mean of the ΔR determinations was −79 ± 17 14C yr, which indicates a consistent, reduced offset between atmospheric and surface ocean 14C specific activity for these sites during this period, relative to the present day (ΔR = ∼0 14C yr). We discuss the significance of this revised ΔR correction by using the example of wheelhouse chronologies at Hornish Point and their development in relation to brochs. In addition, we assess the importance of using the concepts of MRE correction and ΔR variations when constructing chronologies using 14C measurements made on materials that contain marine-derived carbon.
Seasonal Radiocarbon Variation of Surface Seawater Recorded in A Coral from Kikai Island, Subtropical Northwestern Pacific
Authors: Morimoto Maki , Kitagawa Hiroyuki , Shibata Yasuyuki , Kayanne Hajime
Published: July 2016

A coral radiocarbon (Δ14C) investigation with a high time-resolution is crucial for reconstructing secular and seasonal Δ14C changes in the surface seawater which potentially reflect ocean circulations and dynamic ocean-atmosphere interactions. The Δ14C values of a modern coral (Porites sp.) from Kikai Island, southern Japan, in the subtropical northwestern Pacific, were determined for the period of 1991-1998 at a monthly resolution. A coral Δ14C time series for the 8 yr indicated seasonal cycles superimposed on a secular decreasing trend of 3.8 per yr. The seasonal amplitude of the coral Δ14C was about 18 on the average, and the minimum Δ14C was observed in late spring and summer. The Δ14C changes were tentatively explained by horizontal oceanic advections around Kikai Island or over the wide range of the equatorial and sub-equatorial Pacific.
Temporal Changes in Radiocarbon Reservoir Age in the Dead Sea-Lake Lisan System
Authors: Stein Mordechai , Migowski Claudia , Bookman Revital , Lazar Boaz
Published: July 2016

The Holocene Dead Sea and the late Pleistocene Lake Lisan were characterized by varying radiocarbon reservoir ages ranging between 6 and 2 ka in the Dead Sea and between 2 ka and zero in Lake Lisan. These changes reflect the hydrological conditions in the drainage system as well as residence time of 14C in the mixed surface layer of the lake and its lower brine. Long-term isolation of the lower brine led to 14C decay and an increase in the reservoir age. Yet, enhanced runoff input with atmospheric 14C brings the reservoir age down. The highest reservoir age of 6 ka was recorded after the sharp fall of the Dead Sea at ~8.1 ka cal BP. The lower reservoir age of zero was recorded between 36 and 32 ka cal BP, when the Lake Lisan mixed layer was frequently replenished by runoff.
The Cosmic Ray Increases At 35 and 60 Kyr BP
Authors: Florinski V , Axford W I , Zank G P
Published: July 2016

Concentrations of 10Be in ice cores and marine sediments exhibit 2 peaks with significant enhancements at 35,000 and 60,000 BP. This radioisotope is produced in the upper atmosphere by spallation of cosmic-ray protons and secondary neutrons on atmospheric nitrogen and oxygen. Previously suggested explanations for the increases include geomagnetic field reversals, a decrease in solar activity, and a supernova explosion. We propose an alternative explanation which involves a change in the galactic environment of the solar system. The structure of the heliosphere is investigated for a period when the Sun enters a cold, dense, unmagnetized interstellar cloud. Under these conditions, the heliosphere contracts to 25% its present size, significantly affecting galactic cosmic ray modulation and increasing anomalous cosmic ray fluxes. A tenfold increase in anomalous cosmic ray flux and a twofold increase in galactic cosmic ray intensity at Earth are possible in this high-density case if heliosheath modulation is reduced. We show that this increase in galactic cosmic ray intensity could be responsible for the peaks in 10Be records.
Holocene Evolution of the Outer Lake of Hwajinpo Lagoon On the Eastern Coast of Korea; Environmental Changes with Holocene Sea-Level Fluctuation of the East Sea (Sea of Japan)
Authors: Yum Jong-Gwon , Yu Kang-Min , Takemura Keiji , Naruse Toshiro , Kitamura Akihisa , Kitagawa Hiroyuki , Kim Jong-Chan
Published: July 2016

The evolution of the outer lake of Hwajinpo Lagoon in Korea has been reconstructed using environmental proxies (lithologic, geochemical, and fossil data) with a chronology established using 7 accelerator mass spectrometry (AMS) radiocarbon dates. Grain size, water content, and X-ray analyses from the core of outer coastal lakes (HJ99) were used to reconstruct sedimentary environments by using total organic carbon, C/N, S, and C/S chemical proxies. Assemblages of mollusc remains also provided paleoenvironmental information. The environmental changes of the outer lake of Hwajinpo Lagoon can be divided into 6 depositional phases. The basin of the Hwajinpo was exposed and underwent a weathering process before the Holocene period. The muddy sand layer on the weathered bedrock indicated an estuarine system about 6000 BP. The laminated layer implies that the lagoonal system was anoxic between about 5500–2800 BP. The marl layer implies a relatively oxic lagoonal condition with mollusc presence about 2500 B P. The layer of very low sulfur content indicates a freshwater lake system isolated by a sand barrier about 1700 BP. Beginning about 1000 B P, the river system deposits progress progradation on the marl layer. Two erosional landforms could be related with a high standing sea level span during Holocene. These high-stands are dated at 5700 BP and 2200 BP and are supposed to have formed erosional landforms of about 1.6 amsl and 0.8 amsl, respectively. Environmental changes of the outer lake of Hwajinpo Lagoon are considered due mainly to the lake- and sea-level fluctuation during Holocene.
14C Chronology of Mesolithic Sites from Poland and the Background of Environmental Changes
Authors: Pazdur Anna , Fogtman Mariusz , Michczyński Adam , Pawlyta Jacek , Zając Miroslaw
Published: July 2016

Mesolithic sites in modern Poland are mainly located in the southern part of the country. Radiocarbon dating of organic material, such as charcoals, wood, and peat, provide a time frame of human settlements in those regions, and dating of speleothems and peat formations provide information on climatic conditions and the timing of climatic change in the region. Here, we present the results of calibrated 14C ages from 3 main Mesolithic sites: Glanów, Chwalim, and Całowanie. Summary probability density distributions of the calendar ages were obtained, and time ranges were ascribed to the cultures in conjunction with archaeological information. These distributions also reveal the changes in human settlement.
Testing the Use of Bomb Radiocarbon to Date the Surface Layers of Blanket Peat
Authors: Garnett M H , Stevenson A C
Published: July 2016

The recently formed surface layers of peatlands are archives of past environmental conditions and can have a temporal resolution considerably greater than deeper layers. The low density and conditions of fluctuating water table have hindered attempts to construct chronologies for these peats. We tested the use of the radiocarbon bomb pulse to date recently accumulated peat in a blanket mire. The site was chosen because the peat profiles contained independent chronological markers in the form of charcoal-rich layers produced from known burning events. We compared chronologies derived from accelerator mass spectrometry 14C analysis of plant macrofossils against these chronological markers. The bomb 14C-derived chronologies were in broad agreement with the charcoal dating evidence. However, there were uncertainties in the final interpretation of the 14C results because the pattern of 14C concentration in the peat profiles did not follow closely the known atmospheric 14C record. Furthermore, samples of different macrofossil materials from the same depth contained considerable differences in 14C. Suggested explanations for the observed results include the following: i) minor disturbance at the site, ii) in-situ contamination of the 14C samples by carbonaceous soot, and iii) differential incorporation of plant material during blanket peat growth.
Seasonal and Secular Variations of Atmospheric 14Co2 Over the Western Pacific Since 1994
Authors: Kitagawa H , Mukai Hitoshi , Nojiri Yukihiro , Shibata Yasuyuki , Kobayashi Toshiyuki , Nojiri Tomoko
Published: July 2016

Air sample collections over the western Pacific have continued since 1992 as a part of Center for Global Environmental Research, National Institute for Environmental Studies (CGER-NIES) global environmental monitoring program. The air samples collected on the Japan-Australia transect made it possible to trace the seasonal and secular 14CO2 variations, as well as an increasing trend of greenhouse gases over the western Pacific. A subset of CO2 samples from latitudes of 10–15°N and 23–28°S were chosen for accelerator mass spectrometry (AMS) 14C analysis using a NIES-TERRA AMS with a 0.3–0.4% precision. These 14CO2 records in maritime air show seasonal variations superimposed on normal exponential decreasing trends with a time constant of about 16 yr. The Δ14C values in the Northern Hemisphere are lower those in the Southern Hemisphere by 3–4 during 1994–2002. The Northern Hemisphere record shows relatively high seasonality (2.3 ± 1.5) as compared with the Southern Hemisphere (1.3 ± 1.2). The maximum values of seasonal cycles appear in late autumn and early winter in the Northern and Southern Hemispheres, respectively. Oscillations of 1–10 yr over the western Pacific are found to correlate possibly with the El Niño/Southern Oscillation (ENSO) events.
14C Concentrations of Single-Year Tree Rings from About 22,000 Years Ago Obtained Using A Highly Accurate Measuring Method
Authors: Gandou Toshiyuki , Sakurai Hirohisa , Katoh Wataru , Takahashi Yousuke , Gunji Syuichi , Tokanai Fuyuki , Matsuzaki Hiroyuki
Published: July 2016

We have measured the radiocarbon concentrations in single-yr tree rings of old wood by accelerated mass spectrometry (AMS) using a multicathode. The 14C concentrations of 10 single-yr tree rings were measured in 100 tree rings at intervals of 10. For each single-yr tree-ring sample, typically 80 measurements of the 14C concentrations were carried out using multicathodes. The sample standard deviations indicated that there are other fluctuations of typically 1.5%, in addition to the fluctuation of the Poisson counting statistics which is typically 3% for each measurement. The average 14C date of the tree rings was 22,130 ± 306 BP for all 624 data of single-yr tree-ring samples measured by the multicathodes. From the calibration data of Lake Suigetsu, the calendar dates of these 100 tree rings were located between 25,400 cal BP and 26,150 cal BP. The 14C dates changed between 21,979 BP and 22,272 BP, with an error of approximately 50 BP, corresponding to a precision of approximately 0.5%. There was a step with a change of approximately 144 BP for each 10 yr in the time profile.
Interpreting Radiocarbon Dates Using Evidence from Tree Rings
Authors: Bayliss Alex , Tyers Ian
Published: July 2016

Often it is not possible to date a sample of wood from the final growth ring of the tree from which it came. In these cases, an “old-wood offset” is apparent. A number of quantitative approaches for the assessment of this offset are available, dependent on the actual tree rings that have been dated. A range of examples are given, demonstrating how such radiocarbon measurements can be interpreted using additional information from archaeology and dendrochronology.
A 14C Calibration with AMS from 3500 to 3000 BC, Derived from A New High-Elevation Stone-Pine Tree-Ring Chronology
Authors: Dellinger Franz , Kutschera Walter , Nicolussi Kurt , Schießling Peter , Steier Peter , Maria Wild Eva
Published: July 2016

High-precision radiocarbon accelerator mass spectrometry (AMS) measurements of a new high-altitude stone-pine tree-ring chronology from the European Alps were performed for a 500-yr stretch in the second half of the 4th millennium BC. A 14C calibration curve with a typical 1-σ uncertainty of about 20 14C yr was achieved. Although the general agreement of our data set with INTCAL98 is very good (confirming once more that INTCAL98 is also proper for calibration of samples of extraordinary sites), we found small deviations of 17 ± 5 14C yr, indicating possible seasonal effects of the delayed growing season at high altitude.
Influence of 14C Concentration Changes in the Past On Statistical Inference of Time Intervals
Authors: Michczyński Adam
Published: July 2016

The influence of the calibration curve on the statistical inference of time intervals was investigated. For this purpose, the calculation of the summed probability density function was used. Computer simulations were done for batches of 11 samples, each time uniformly covering 200-yr time intervals. The results show that the calibration curve causes the summed probability density function of a group to cover a wider interval than the real-time interval of the phenomenon. Moreover, the estimated time interval may be often shifted in relation to the real-time interval.
Trondheim Natural Radiocarbon Measurements V
Authors: Nydal Reider , Lövseth Knut , Syrstad Oddveig
Published: July 2016

The present date list covers mainly the datings done from 1964 to 1968. Each sample is measured in one of the two counting units described earlier (Nydal, 1965). The background of the counters has been somewhat reduced during the past few years. Counter 2 with an effective volume of 1.5 L (1.9 L total volume), has a background of 0.9 counts/min, and a recent standard net count of 19.2 counts/min. Counter 3, with an effective volume of 1.1 L (1.3 L total volume), has a background of 2.4 counts/min and a recent standard net count of 14.2 counts/min.
Tartu Radiocarbon Dates IV
Authors: Ilves E. , Punning J.-M. , Liiva A.
Published: July 2016

The following list includes C14 dates and deals with the results of the methodological investigations carried out at the Geobiochemical Laboratory of the Institute of Zoology and Botany of the Academy of Sciences of the Estonian SSR in 1967–1968.
U. S. Geological Survey Radiocarbon Dates XI
Authors: Sullivan Beverly Marsters , Spiker Elliott , Rubin Meyer
Published: July 2016

This list contains the results of measurements made during 1967 and 1968. Samples are counted in the form of acetylene gas, as previously, and ages computed on the basis of the Libby half-life, 5568 ± 30 yr. The error listed, always larger than the one-sigma statistical counting error commonly used, takes into account variable laboratory factors, but does not include external (field or atmospheric) variations.
University of Wisconsin Radiocarbon Dates VII
Authors: Bender Margaret M. , Bryson Reid A. , Baerreis David A.
Published: July 2016

The radiocarbon dates obtained since August, 1968, are reported here. Wood, charcoal, and peat samples are pretreated with dilute NaOH and dilute H3PO4 before conversion to the methane used as counting gas; marls and lake cores are treated with acid only. The reported dates have been calculated using 5568 years as the half-life of C14, 1950 as the reference year. Samples are run at least once in each of two 0.5 liter counters at 3 atm pressure for a minimum total of 15,000 counts. The standard deviation quoted includes only the 1σ of the counting statistics of background, sample, and standard counts.
Gakushuin Natural Radiocarbon Measurements I
Authors: Kigoshi Kunihiko , Tomikura Yoshio , Endo Kunihiko
Published: July 2016

Natural C14measurements have been performed at Gakushuin University since 1959, using a proportional counter of 400 ml (Kigoshi and Tomikura, 1960). The counter presently in service is made of copper tubing and has an effective volume of 900 ml. Acetylene gas is used as counting gas at pressure 600–760 mmHg and prepared in the same way as in the case of 400 ml counter. The counter is shielded by iron sheets of 23-cm thickness and by anti-coincidence with a multianode propane-flow proportional counter of Houterman's type (Houtermans, 1958). A background of 5.6 counts/min has been attained with this counter arrangement. The modern carbon sample filled at 0°C and 760 mmHg shows an activity of 11.8 counts/min. The samples with code numbers greater than GaK-60 were measured by this counter.
Louvain Natural Radiocarbon Measurements I
Authors: Dossin J. M. , Deumer J. M. , Capron P. C.
Published: July 2016

The following list covers the samples measured at the Louvain C14dating laboratory during a period from May to December 1961.
La Jolla Natural Radiocarbon Measurements II
Authors: Hubbs Carl L. , Bien George S. , Suess Hans E.
Published: July 2016

Since the publication of the last list of C14measurements (La Jolla I), covering the period from mid-1957 through 1959, the La Jolla Radiocarbon Laboratory has continued to use essentially the same technique. In the summer of 1961 a second Oeschger-Houtermans counter (Houtermans and Oeschger, 1958), purchased from Manufacture Belge de Campes et de Matériel Electronique, S. A., was installed. It has a somewhat higher background (3.1 counts/min at a filling pressure of 880 mm) than the counter obtained from Bern—a point of little significance in the measurements herein reported. Of the tests included in this report only those following LJ-380 were run with the new counter; the others, with the Bern counter.
National Physical Laboratory Radiocarbon Measurements I
Authors: Callow W. J. , Baker M. J. , Pritchard D. H.
Published: July 2016

The dating equipment at the National Physical Laboratory was completed by the summer of 1960. A series of calibration and intercomparison measurements was undertaken however, using the NBS oxalic acid reference standard, a modern wood standard (1850 oak tree) and other material before starting routine measurements toward the end of 1961. All results have been obtained using a 4.5 L copper proportional counter filled with CO2 at a constant density corresponding to standard conditions of 22°C and an absolute pressure of 150 cm Hg. The counter is shielded by 8 in. of steel, 6 in. of paraffin wax containing boric oxide, 23 Geiger counters arranged as two independent groups and finally by 1 in. of mercury.
Stockholm Natural Radiocarbon Measurements V
Authors: Östlund H. Göte , Engstrand Lars G.
Published: July 2016

This date list includes samples and sample series finished between January and November 1962. It does not include samples from series not yet been completed, or samples of very limited scientific interest.
University of Michigan Radiocarbon Dates VIII
Authors: Crane H. R. , Griffin James B.
Published: July 2016

The following is a list of dates obtained since the time of the compilation of List VII in December 1961. The method is essentially the same as that used for the work described in the previous list. Two CO2-CS2 Geiger counter systems are used. The equipment and counting technique have been described elsewhere (Crane, 1961a, 1961b). The dates and the estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conference of 1962, in that (a) dates are computed on the basis of a half life of 5568 years, (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 all previous Michigan date lists we have quoted errors at least twice as great as the statistical errors of counting, in order to take account of other errors in the over-all process. If the reader wishes to obtain a standard deviation figure which will allow ample room for the many other sources of error in the dating process, we suggest he double the figures that are given in this list. The procedures for converting the dates to the more recent half life scale and to a scale having its zero at any time other than 1950 need not be given here as they have been covered in this journal and elsewhere. Where there is no comment, it is because the submitter of the sample had none to make.
Louvain Natural Radiocarbon Measurements III
Authors: Gilot E. , Ancion N. , Capron P. C.
Published: July 2016

The following list covers the samples measured at the Louvain C14 dating laboratory in 1964.
University of Pennsylvania Dates VII
Authors: Ralph Elizabeth K. , Michael Henry N. , Gruninger John
Published: July 2016

Measurements of samples of known age have been undertaken in this laboratory since its beginning in 1951 when it was found that modern wood samples taken from the outer rings of young trees did not afford a basis of counter calibration consistent with archaeologically dated samples (Ralph, 1955). This depletion was explained by Suess (1955). Subsequent measurements of samples representative of the early Egyptian dynasties, however, revealed that even with the counter calibration corrected for the modern depletion, there was a discrepancy between C14 dates and the early Egyptian chronology (Arnold and Libby, 1951; deVries, Barendsen, and Waterbolk, 1958; deVries and Waterbolk, 1958; Barker and Mackay, 1959, 1961; Ralph, 1959; Damon and Long, 1962). Obviously, there was, and still is, a need to find samples of known age for this time range. Dendrochronology may ultimately provide the answer, and in the meantime tree-ring dated samples have afforded a means of assessing the atmospheric C14 inventory during the last 3000 yr.
University of Pennsylvania Radiocarbon Dates VIII
Authors: Stuckenrath Robert , Ralph Elizabeth K.
Published: July 2016

This date list includes those series of archaeologic samples completed in this laboratory during 1963 and 1964. The b.p. ages are calculated from a.d. 1950, and are based upon a half-life value of 5568 yr. Errors quoted do not include the half-life error. All samples have been pretreated with 3N HCl, and some, where noted, have received an additional 2% NaOH pretreatment for the removal of possible humic acid contaminants.
U. S. Geological Survey Radiocarbon Dates VIII
Authors: Levin Betsy , Ives Patricia C. , Oman Charles L. , Rubin Meyer
Published: July 2016

This list contains the results of measurements made during 1963 and 1964. Samples are counted in the form of acetylene gas, as previously, and ages computed using the Libby half-life of 5568 ± 30 yr. The error listed is always larger than the one-sigma statistical counting error commonly used, takes into account known uncertainty laboratory factors, but does not include external (field or atmospheric) variations.
ANU Radiocarbon Date List VIII
Authors: Polach H A , McLean R F , Thom B G , Stoddart D R , Hopley David , Wilkie Stella
Published: July 2016

The aims of the 1973 Great Barrier Reef Expedition's radiocarbon dating programs were: 1) to collect live specimens from various reef environments to serve as modern reference standards, 2) to evaluate suitability of materials from drilling, geomorphic, and sediment programs for dating purposes, and 3) to date appropriate samples related to those programs. Radiometric ages provide a time scale for evolution of reefs and reef islands, and the history of sea level in the area.
Marine Resources Research Institute Radiocarbon Dates IV
Authors: Mathews Thomas D , Kearns Fonda L
Published: July 2016

The results presented in this date list are from the same sampling program previously reported (R, 1978, v 20, p 436–440). Each sample reported herein was geologic in origin and, in most instances, represents a single shell date.
Quebec Radiocarbon Measurements III
Authors: Barrette Louis , Salle Pierre La , Samson Claude
Published: July 2016

The results presented in this list have been obtained by benzene synthesis and liquid scintillation counting: ages are calculated using the 14C half-life of 5570 yr with 0.95 activity of NBS oxalic acid as modern standard, with no correction. The given precision is obtained from a one-standard-deviation criterion.
Is Classical Acid-Alkali-Acid Treatment Responsible for Contamination? An Alternative Proposition
Authors: Hatté Christine , Morvan Jean , Noury Claude , Paterne Martine
Published: July 2016

It is well known that, during the widely used AAA pretreatment (de Vries and Barendsen 1954), alkali treatment is responsible for the incorporation of modern carbon due to the precipitation of atmospheric CO2 as carbonate. Until now, the last step of the experiment, consisting in acid treatment (most of the time with hydrochloric acid) was considered to be sufficient to eliminate all of lab contamination. But wood, peat and sediment present a complex molecular structure. During radiocarbon chemical treatments, functional groups still present in the molecules are likely to form ionic bonds with “modern” carbonates. These new chemical bonds resist a “classical” acid treatment and are responsible for rejuvenation. This short paper presents preliminary results for two common 14C cases: rejuvenation of a 0.4 pMC wood and of an Oxygen Isotope Stage 3 (OIS3) paleosol. For both cases, contamination due to incorporation of modern carbon during chemical treatment is evaluated and an alternative protocol is proposed.
Pretreatment of Iron Artifacts at SNU-AMS
Authors: Cheoun M K , Kim J C , Kang J , Kim I C , Park J H , Song Y M
Published: July 2016

We present the current status of accelerator mass spectrometry (AMS) dating of iron artifacts at Seoul National University (SNU). In ancient iron production, charcoal was widely used as carbon for the smelting process, whereas coal is used in modern times. If reliable data could be obtained from carbon by using AMS, ancient iron artifacts could be traced to their production age. In normal acid treatment, it is not easy to extract carbon due to its colloidal property. The negative charge property of the carbon colloid, however, makes it possible for it to be precipitated with positive ions by dissolving the iron chemically. An extraction yield of the carbon incorporated in modern cast iron of about 70% is attained. More refined methods to increase the extraction rate are under progress for archaeological applications.
Radiocarbon Dating of Wood Using Different Pretreatment Procedures: Application to the Chronology of Rotoehu Ash, New Zealand
Authors: Santos G M , Bird M I , Pillans B , Fifield L K , Alloway B V , Chappell J , Hausladen P A , Arneth A
Published: July 2016

We compare radiocarbon accelerator mass spectrometry (AMS) ages of wood samples subjected to a conventional acid-base-acid pretreatment with stepped combustion (ABA-SC) with results from the same samples subjected to an acid-base-wet oxidation pretreatment with stepped combustion (ABOX-SC) and cellulose extraction with stepped combustion (CE-SC). The ABOX-SC procedure has been shown previously to lead to lower backgrounds for old charcoal samples. Analyses of relatively uncontaminated “14C-dead” samples of wood suggest that backgrounds of 0.11 ± 0.04 pMC are obtainable for both the ABOX-SC and ABA-SC procedures. Where wood is significantly contaminated the ABOX-SC technique provides significantly better decontamination than either the ABA-SC technique or cellulose extraction alone, although CE-SC can produce comparably low backgrounds to the ABOX-SC procedure.

We also report the application of the ABOX-SC, ABA-SC and CE-SC procedures to wood samples associated with the chronologically controversial Rotoehu Ash eruption, New Zealand. New 14C-AMS dates from wood sampled from below the Rotoehu Ash span an age range of 43–50 ka BP consistent with recently presented OSL dates of 42–44 ka obtained for palaeosols beneath the ash.
An Extraction System to Measure Carbon-14 Terrestrial Ages of Meteorites with a Tandetron AMS at Nagoya University
Authors: Minami M , Nakamura T
Published: July 2016

We have constructed a system to extract carbon from meteorites using a vacuum-tight RF melting method in order to study radiocarbon activities in meteorites. The extraction system was examined using iron standards of known carbon content. The carbon extraction efficiencies and 14C ages of the iron standards by this method were compared with the results obtained previously by our older melting system and a wet oxidation method. Higher collection efficiencies of about 90% for the iron samples of relatively high carbon content were achieved by the new system. The efficiency of extracting a small amount of carbon is also near 90% after improving the extraction procedure. The 14C ages of the iron standards were compared to the ages by the wet method. The results indicate that contamination by modern carbon is negligible in the system. Furthermore, terrestrial 14C ages of two Antarctic meteorites, Y-75102 and ALH-77294, from the Yamato and Allan Hills ice fields, respectively, were determined. The age of Y-75102 is estimated 4.0 ± 1.0 ka, and the age of ALH-77294 is 19.5 ± 1.2 ka. The 14C ages on the meteorites roughly agree with the literature value. However, further study is needed in improvement on reducing a background value and of complete fusion of a meteorite in the extraction system.
The Filling of Gaps in Geophysical Time Series by Artificial Neural Networks
Authors: Dergachev V A , Gorban A N , Rossiev A A , Karimova L M , Kuandykov E B , Makarenko N G , Steier P
Published: July 2016

Nowadays, there is a large number of time series of natural data to study geophysical and astrophysical phenomena and their characteristics. However, short length and data gaps pose a substantial problem for obtaining results on properties of the underlying physical phenomena with existing algorithms. Using only an equidistant subset of the data with coarse steps leads to loss of information. We present a method to recover missing data in time series. The approach is based on modeling the time series with manifolds of small dimension, and it is implemented with the help of neural networks. We applied this approach to real data on cosmogenic isotopes, demonstrating that it could successfully repair gaps where data was purposely left out. Multi-fractal analysis was applied to a true radiocarbon time series after recovering missing data.
Solar Activity and Regional Climate
Authors: Ogurtsov M G , Kocharov G E , Lindholm M , Eronen M , Nagovitsyn Yu A
Published: July 2016

We performed a statistical analysis of the data on summer temperature anomalies in northern Fennoscandia (8–1995 AD) and found that a 70–130-yr cycle is present in this series during most of the time period. A comparison of the reconstructed northern Fennoscandia temperature with different indicators of solar activity (Wolf numbers, the length of solar Schwabe cycle, extended bi-decadal radiocarbon series, and data on sunspots observed by naked eye) shows that the more probable cause of the periodicity is the modulation of regional northern Fennoscandia climate by the long-term solar cycle of Gleissberg. The effect of this century-scale solar modulation of the global Northern Hemisphere temperature is weaker.
Radiocarbon Measurements of Tree Rings from 14 ka Huon Pine
Authors: Lange T , Barbetti M , Donahue D J
Published: July 2016

We have measured the radiocarbon content of tree rings from a section of Huon pine retrieved from Tasmania. The sample was divided into 39 five-ring sub-samples covering a period of 194 years. Radiocarbon ages of each of these sub-samples was determined by making four measurements of each sub-sample at the Arizona AMS laboratory (Table 1). The resulting 1σ precisions are about 0.5%. A comparison of our data with the appropriate curve in INTCAL98 indicates that the calendar age of our sample is close to 14,000 cal BP. Using this age calibration, we have constructed a plot of Δ14C versus assumed calendar age. This plot shows an essentially constant value over the youngest 125 rings of our sample. Over the oldest 75 yr of the sample, the Δ14C curve exhibits three fluctuations, the largest of which is about 65‰. The time of the peaks in the Huon-pine 14C curve corresponds approximately with the European Bølling/Allerød climatic event. Work is in progress to extend the data 100 yr more toward older ages.
A Freshwater Diet-Derived 14C Reservoir Effect at the Stone Age Sites in the Iron Gates Gorge
Authors: Cook G T , Bonsall C , Hedges R E M , McSweeney K , Boronean V , Pettitt P B
Published: July 2016

Human bones from single inhumation burials and artifacts made from terrestrial mammal (ungulate) bone found in direct association with the skeletons were obtained from the Stone Age site of Schela Cladovei situated just below the Iron Gates Gorge of the River Danube. The results of stable isotope analyses of the human bone collagen are consistent with a heavy dependence on aquatic protein while radiocarbon dating of the samples reveals an offset of 300–500 years between the two sample types, indicating a freshwater reservoir effect in the human bone samples. Since protein consumption is by far the major source of nitrogen in the human diet we have assumed a linear relationship between δ15N and the level of aquatic protein in each individual's diet and derived a calibration for 14C age offset versus δ15N which has been applied to a series of results from the site at Lepenski Vir within the gorge. The corrected 14C ages (7310-6720 BP) are now consistent with the previous 14C age measurements made on charcoal from related contexts (7360–6560 BP). In addition, the data indicate a change from a primarily aquatic to a mixed terrestrial/aquatic diet around 7100 BP and this may be argued as supporting a shift from Mesolithic to Neolithic. This study also has wider implications for the accurate dating of human bone samples when the possibility exists of an aquatic component in the dietary protein and strongly implies that δ15N analysis should be undertaken routinely when dating human bones.