bluuebunny/crossref_metadata_2025 huggingface dataset:
Calibration Technique for 14C Data Clusters: Fitting Relative Chronologies onto Absolute Time Scales
Authors: Haas Herbert , Doubrava Matthew R.
Published: July 2016

Application of radiocarbon dating to a short chronology is often limited by the wide probability ranges of calibrated dates. These wide ranges are caused by multiple intersections of the 14C age with the tree-ring curve. For a single unrelated 14C date, each intersection presents a probable solution. When several dates on different events are available, identification of the most probable solution for each event is possible if one can obtain some information on the relation between these events. We present here a method for such identifications.

To demonstrate the method, we selected a series of 14C dates from mortuary monuments of the Egyptian Old Kingdom. Corrected 14C dates from seven monuments were used. Calibration of these dates produced three absolute ages with single intersections and four ages with 3–5 intersections. These data are compared to a historical chronology, which places the dated events at a younger age. If each intersection is chosen as a potential anchor point of the “correct” chronology, 17 solutions must be tested for the best fit against the historical chronology. The latter is based on the length of the reign of each pharaoh during the studied time span. The spreadsheet has the function of determining the probability of fit for each of the solutions. In a second step the 17 probability values and their offset between the historical and the 14C chronology are graphically analyzed to find the most probable offset. This offset is then applied as a correction to the estimated chronology to obtain an absolute time scale for the dated events.
Dating Grimes Graves
Authors: Ambers Janet
Published: July 2016

More radiocarbon analyses have been produced for the Neolithic flint mines of Grimes Graves than for any other site with which the British Museum's Radiocarbon Laboratory has been involved. Despite this heavy concentration of effort, a recent review of these figures concluded that poor sample selection, combined with a lack of sufficient quality assurance procedures, severely limit the use that can be made of this database. To overcome these difficulties, a redating program has been undertaken using a carefully selected subset of the original material. In this paper I discuss the flaws in the original data set, due to both technical and sampling problems; set out ways to avoid similar problems in the future, with particular reference to quality assurance; and discuss the new results and their archaeological implications.
Climatic Events and Upper Paleolithic Chronology in the Dniester Basin: New 14C Results from Cosautsi
Authors: Haesaerts Paul , Borziak Ilic , Van Der Plicht Johannes , Damblon Freddy
Published: July 2016

We discuss the radiocarbon chronology of the loess deposited during the Upper Pleniglacial (Isotope Stage II) for the key site of Cosautsi (Republic of Moldova), which presents some major problems in 14C dating. Special care was paid to accurate microstratigraphic positioning of samples, collection of top-quality material (mainly conifer charcoal), and selection of uncontaminated pieces for dating and crossdating with bones by accelerator mass spectrometry (AMS) and/or conventional 14C dating. The results provide reliable and precise information on the sedimentation processes, the succession of short climatic events and the cycle of recurrent human settlements on the site between ∼20,000 and 16,000 bp. Two sets of climatic improvements can be ascribed to interstadial oscillations named, successively, Cosautsi VI (19,500–19,000 bp) and Cosautsi V (18–17,500 bp).
Duration of Tell Settlements at Four Prehistoric Sites in Hungary
Authors: Hertelendi Ede , Svingor Eava , Raczky Pál , Horváth Ferenc , Futó István , Bartosiewicz László
Published: July 2016

The chief objective of this paper is to improve our understanding of the Neolithic in eastern Hungary using absolute chronological data. To accomplish this we calibrated new measurements as well as previously published dates. The up-to-date, standardized evaluation of 147 calibrated measurements showed temporal overlaps between archaeological cultures defined on the basis of ceramic styles. The average timespan of tell settlements of 285 yr was obtained using radiocarbon dates from four major settlements in eastern Hungary: Berettyóújfalu-Herpály, Hódmezővásáhely-Gorzsa-Cukortanya, Öcsöd-Kováshalom and Polgár-Csőszhalom.
The First 14C Dating of Monuments in European Scythia
Authors: Zaitseva Ganna I. , Possnert Göran , Alekseev Andrey Yu. , Dergachev Valentin A. , Sementsov Anatoly A.
Published: July 2016

The first radiocarbon dates for the famous monuments of European Scythia were produced for the Kelermes, Seven Brothers, Solocha and Chertomlyk barrows (burial mounds) by both accelerator mass spectrometry (AMS) and conventional methods. The obtained 14C dates confirmed the traditional archaeological chronology, which was based on the analysis of written data and typological comparisons of Scythian artifacts with similar objects found in the Ancient East and Greece. The 14C dates for the European Scythian monuments are compared with the Asian ones. The 14C chronology of the European Scythian monuments shows chronological synchronisms between the Asiatic and European monuments. The calibrated ages for the investigated barrows generally agree with the archaeological data.
AMS 14C Dating of Historic Eruptions of the Kirishima, Sakurajima and Kaimondake Volcanoes, Southern Kyushu, Japan
Authors: Okuno Mitsuru , Nakamura Toshio , Kobayashi Tetsuo
Published: July 2016

In the historic period, several large eruptions were recorded from Kirishima, Sakurajima and Kaimondake volcanoes in southern Kyushu, Japan. Estimated dates of volcanic activity were established on these volcanoes through historical documentation of major eruption events. This study presents the correspondence between these documents and the records of AMS 14C dating of soils underlying tephra layers. We conclude that AMS 14C dates of soil materials can be useful in correlating tephra layers with documentary records of eruption.
14C AMS Dating of Icelandic Lake Sediments
Authors: Sveinbjörnsdóttir Árný E. , Heinemeier Jan , Kristensen Peter , Rud Niels , Geirsdóttir Áslaug , Harđardóttir Jórunn
Published: July 2016

We report an age-depth profile for the sediments of the Lake Hesrvatn, southern Iceland, based on 14C analyses of the organic fraction of bulk sediment samples, molluscs and foraminifera. Our age-depth curve is supported by the occurrence of the well-dated Vedde ash in the lowermost part of the sediments. Comparison of foraminifera dates with the age of the Vedde ash indicates a reservoir age of ca. 400 yr. The results suggest that the sediments at Hestvatn accumulated in a marine environment until ca. 8700 bp and thereafter in freshwater.

Owing to the lack of terrestrial macrofossils and the low concentration of molluscs and foraminifera, we were forced to attempt to date most of the core with the organic fraction of the bulk sediment samples. We found, however, that this fraction is not homogeneous in density or 14C age. We believe that during sample pretreatment we managed to isolate a light organic fraction, which closely represents the true age of the sediment, whereas the denser fraction yields ages that are too high. This age diversity may to some extent be explained by the large drainage area of the lake, from which plant remains of different ages may have been washed into the lake.
14C and 234U-Excess Dating of Groundwater in the Haifa Bay Region Israel
Authors: Rogojin Vasily , Carmi Israel , Kronfeld Joel
Published: July 2016

Radiocarbon activities and uranium isotopic disequilibria were measured in water samples from both the sandy Pleistocene coastal aquifer and within the upper Cretaceous Judea Group carbonate aquifer of northwestern Israel. The samples in both aquifers exhibit a decrease in 14C activity that is concomitant to the growth in 234U-excess. This suggests that under specific conditions, 234U-excess dating of groundwater can be used to corroborate 14C dates, while offering the possibility of extending the range of dating of groundwater beyond that of 14C.
A Simple Method to Separate Pollen for AMS Radiocarbon Dating and its Application to Lacustrine and Marine Sediments
Authors: Mensing Scott A , Southon John R
Published: July 2016

We present a simple method for manually separating pollen concentrates for radiocarbon accelerator mass spectrometry (AMS) dating using a mouth pipetting system. The required equipment is readily available from scientific equipment supply houses at minimal cost. Pollen samples from lake sediments required about 4 h of hand picking, whereas samples from marine sediments required about 8 h labor. Pollen dates from marine sediments were much older than expected. We are attempting to resolve whether this is due to contamination of the pollen or the presence of significant quantities of old reworked pollen. Pollen dates from lake sediments associated with Mazama Ash were consistent with other published ages; however, replicate dates on pollen samples from above the ash were consistently older than the surrounding sediment. Our results suggest that caution must be used when interpreting pollen dates if the potential for sediment reworking is present.
Variations of Isotopic Composition of Carbon in the Karst Environment from Southern Poland, Present and Past
Authors: Pazdur Anna , Goslar Tomasz , Pawlyta Mirosława , Hercman Helena , Gradziński Michał
Published: July 2016

We describe a comprehensive study of carbon isotopes in several karst springs and their environs in a contemporary karst environment in the region of the Cracow-Wieluñ Upland and Western Tatra Mountains, Southern Poland. We collected samples of water, plants and carbonate deposited on aquatic plants, and obtained13C values and14C concentrations. We also investigated a group of the youngest calcium carbonates from caves where deposition is still being observed or ceased no more than a few hundred years ago. The determination of a14C dilution factor (q) in these carbonates allows us to determine the “true” radiocarbon ages of old speleothems from caves in the area under investigation and enables the use of old speleothems as suitable material for extending the14C calibration time scale, the “Absolute” age having been determined by U/Th or amino acid racemization (AAR) dating methods. Measurements of δ13C and14C concentrations were made on dissolved inorganic carbon (DIC) extracted from water samples. Calculated values of q range from 0.55 to 0.68 and δ13C values range from −10% to −13% versus VPDB with mean values equal to 0.65 and −12%, respectively. Results indicate that the dissolution process of limestone bedrock is a closed system with the dominating contributor being biogenic carbon dioxide.

Isotopic composition of carbon in contemporary plants collected at the karstic springs at 3 localities is highly diverse, with different species distinctly varying in both q and δ13C values. Extremely light values of13C (under −40%), observed in Algae andHyloconium splendens, are correlated with14C concentrations that are much lower than 100 pMC. Small systematic changes of isotopic composition were found in plants of the same species collected along streams at various distances from the spring. The youngest calcium carbonates from different caves show a relatively high scatter of both δ13C values and14C concentration. The lower reservoir effect for14C is observed in samples with higher value of δ13C, indicating equilibrium conditions in the sedimentation of carbonate. Pazdur et al. (1995b) presented14C dating results and paleoclimatic interpretation of 17014C analyses of 89 speleothems from 41 caves obtained through 1994. Investigations continued until early 1997, during which time a speleothem, JWi2, was dated by14C, U/Th and AAR dating methods, and its stable isotope composition (δ13C and δ18O) analyzed in detail (reported here). Carbon isotope analyses indicate very large differences among results obtained by U/Th, AAR, and14C dating methods.
A ΔR Correction Value for Samoa from Known-Age Marine Shells
Authors: Phelan Matthew B
Published: July 2016

A first-order ΔR correction value for marine samples is presented based on 3 radiocarbon determinations of known-age marine shells from Samoa.
Radiocarbon Calibration by the Date Distribution Method
Authors: Muzikar Paul
Published: July 2016

A method is presented for calibrating radiocarbon ages based on statistical analysis of a large number of randomly distributed dates. One interesting feature of this method is that it is internal; that is, it allows one to extend a known calibration curve further back in time by using only 14C dates, with no reference to any other dating technique. A serious difficulty in implementing this method lies in assembling a sample of dates with the correct statistical properties.
AMS Radiocarbon Dates of Kurgans Located On the Ust'-Yurt Plateau, Uzbekistan
Authors: Blau Soren , Yagodin Vadim
Published: July 2016

Recent osteological analyses of archaeological human skeletal remains from the Ust'-Yurt Plateau, Uzbekistan, provided the opportunity to obtain samples for radiocarbon dating. The results of 18 accelerator mass spectrometry (AMS) dates are presented in this paper and provide the first absolute dates for late prehistoric and early historic archaeological sites in Uzbekistan. The AMS dates suggest that most sites are earlier than have been traditionally thought based on relative dating using artifact typologies.
AMS14C Dating of Pollen Concentrate from Late Pleistocene ICE Wedges From the Bison and Seyaha Sites in Siberia
Authors: Vasil'chuk Alla , Kim Jong-Chan , Vasil'chuk Yurij
Published: July 2016

Accelerator mass spectrometry (AMS) radiocarbon dates of pollen concentrate were obtained from multistage syngenetic ice wedges of cross-sections from the Late Pleistocene Bison site, located along the Lower Kolyma River (68°34'N, 158°34'E), from ∼43,600 to ∼26,200 BP, and 3 AMS14C dates of pollen concentrate in ice wedges from the Seyaha site cross-section, located on the east coast of the Yamal Peninsula (70°10'N, 72°34'E), from ∼22,400 to ∼25,200 BP. Pollen concentrate samples were prepared using a special pretreatment procedure. Pollen and spores from ice-wedge ice signalize a regional pollen rain. Therefore,14C-dated extracts of pollen and spores from ice-wedge ice enable an adequate reconstruction and chronology of landscape dynamics on a regional scale. The pollen and spores were well preserved despite numerous redepositions in the penecontemporaneous structure in which they were found. Thus, a comparison with dates on other fractions from the same sample is necessary. The youngest date is the most reliable among the intersample AMS14C dates from the ice and permafrost sediments.
British Museum Natural Radiocarbon Measurements V
Authors: Barker Harold , Mackey John
Published: July 2016

The dates detailed below are based on measurements made from September 1962 to August 1964. Work was often seriously interrupted due to difficulties with electronic equipment and also, from the late summer of 1963, high levels of tritium in the local water supplies used in the synthesis of acetylene (from nuclear weapons tests) made it difficult to obtain accurate measurements with acetylene as a filling gas for the proportional counter. The gas preparation equipment was therefore modified for the preparation of high purity CO2, and from Sample BM-165 onwards, the proportional counter was operated with CO2 as the filling gas at a pressure of 210 cm Hg at 22°C. instead of 140 cm Hg pressure of acetylene at 22°C. as reported previously (British Museum I). Background and net modern count rates under these conditions are 3.59 c.p.m. and 8.35 c.p.m., respectively. (In practice these values are taken as the rolling mean of the past 20 weeks’ measurements and are very constant.) The calculations of age are based on the half-life of 5570 yr and error terms are widened to include contributions of ± 80 yr for possible isotopic fractionation effects and ± 100 yr for de Vries-effects. Safeguards against inaccuracies are as described previously (British Museum I).
Bonn Radiocarbon Measurements I
Authors: Scharpenseel H. W. , Pietig F. , Tamers M. A.
Published: July 2016

The laboratory started dating in 1966 using liquid scintillation techniques. Considerable effort has been expended on improvements in both sample preparation and detection (Pietig and Scharpenseel, 1964 and 1966). Yields now approach 100% and 4 to 6 samples are completed each week. A solution of 3 cc synthesized benzene and 1 cc “dead” commercial toluene is employed for ordinary measurements. Toluene contains PPO and POPOP scintillators that give final concentrations of 0.4% and 0.01%, respectively, when diluted with sample benzene. The counting arrangement with normal shielding gives a net modern count rate of 25.6 cpm (78% efficiency) with a background of 9.7 cpm. A special counter equipped with 5 cm mercury and 10 cm lead shielding as well as an anti-coincidence “umbrella” of polystilbeneplastic scintillator has considerably better characteristics. In addition to reduced background, samples as large as 100 cc can be accommodated. The exceptional performance obtained here is presently reserved for natural radioactivity measurements, such as T-3 and C1–36.
University of Michigan Radiocarbon Dates XII
Authors: Crane H. R. , Griffin James B.
Published: July 2016

The following is a list of dates obtained since the compilation of List XI in December 1965. The method is essentially the same as described in that list. Two CO2-CS2Geiger counter systems were used. Equipment and counting techniques have been described elsewhere (Crane, 1961). Dates and estimates of error in this list follow the practice recommended by the International Radiocarbon Dating Conferences of 1962 and 1965, in that (a) dates are computed on the basis of the Libby half-life, 5570 yr, (b) A.D. 1950 is used as the zero of the age scale, and (c) the errors quoted are the standard deviations obtained from the numbers of counts only. In previous Michigan date lists up to and including VII, we have quoted errors at least twice as great as the statistical errors of counting, 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 sources of error in the dating process, we suggest doubling the figures that are given in this list.

We wish to acknowledge the help of Patricia Dahlstrom in preparing chemical samples and David M. Griffin and Linda B. Halsey in preparing the descriptions.
University of Wisconsin Radiocarbon Dates XXIII
Authors: Steventon Raymond L , Kutzbach John E
Published: July 2016

Procedures and equipment used in the University of Wisconsin laboratory have been described in previous date lists. The preamplifiers and counting system were replaced in 1977 using modified EC & G Ortec components. Except as otherwise indicated, wood, charcoal, and peat samples are pretreated with dilute NaOH-Na4P2O7 and dilute H3PO4 before conversion to the counting gas methane; when noted marls and lake cores are treated with acid only. Very calcareous materials are treated with HCl instead of H3PO4. Pretreatment of bone varies with the condition of the bone sample; solid bone with little deterioration is first cleaned manually and ultrasonically. The bone is treated with 8% HCl for 15 minutes, then dilute NaOH-Na4P2O7 for 3 hours at room temperature, washed until neutral, and the collagen extracted according to Longin (1971). Charred bone is treated with dilute HCl, NaOH-Na4P2O7, and then dilute HCl again.
Radiocarbon Dates of Peats from North Pacific North America
Authors: Heusser Calvin J.
Published: July 2016

Ages are presented for 17 late-Pleistocene peat samples from sections that range from Karluk on Kodiak Island, Alaska to Port Orford, Oregon. Pollen and peat stratigraphy of the sections is used to interpret the environments prevailing at and since the time of sample deposition. The late-glacial at more southerly Pacific coastal Alaskan sites is dated at ca. 10,800 b.p. and the postglacial at ca. 10,000 b.p. At northerly coastal sites these intervals begin somewhat later. Regression rates for sealevel are given for a number of sites along this coast. Sample ages from two Oregon lakes suggest eustatic transgression ca. 5000 b.p. during the Hypsithermal interval.
Stockholm Natural Radiocarbon Measurements II
Authors: Östlund H. Göte
Published: July 2016

This paper is a list of the radiocarbon datings of geologic and archaeologic samples made during 1958 after the dating apparatus had been installed at the Geological Survey. It is a direct continuation of the first dating list (Östlund, 1957a). Some of the results of geophysical interest, measurements of a few sea water samples, have been published separately (Fonselius and Östlund, 1959); others will follow.
Uppsala Natural Radiocarbon Measurements I
Authors: Olsson Ingrid
Published: July 2016

The following list covers the samples measured at the Uppsala radiocarbon laboratory during 1957, when the measurements started, and 1958. Two samples of sediments have been excluded, as the origin of the material was doubtful.
Lamont Radiocarbon Measurements VI
Authors: Broecker Wallace S. , Olson Edwin A.
Published: July 2016

In contrast to previous radiocarbon measurement lists, this list contains only known-age samples, most of which formed during the past ten years. The measurements were made largely in order to gain an understanding of the distribution of radiocarbon within the dynamic carbon reservoir both today and at times in the past. Since all materials forming in this reservoir today do not have the same C14/C12 ratio, such an understanding is necessary in order to arrive at the most accurate possible estimate of the age of samples submitted for dating. This is particularly important when high accuracy (i.e., <100 years error) is required on subaerially grown samples and also when attempting to extend the method to samples which formed in reservoirs other than the atmosphere (for example, the ocean and freshwater systems).
Uppsala Natural Radiocarbon Measurements III
Authors: Olsson Ingrid , Cazeneuve Horacio , Gustavsson John , Karlén Ingvar
Published: July 2016

The following list covers samples measured at the Uppsala radiocarbon laboratory during 1960. The technique used has been described by the senior author (Olsson, 1958). Pretreatment has not been changed since the last dating list was published (Uppsala II).
U. S. Geological Survey Radiocarbon Dates VI
Authors: Rubin Meyer , Berthold Sarah M.
Published: July 2016

Dates in this list have been determined at U. S. Geological Survey radiocarbon laboratory, Washington, since our 1960 date list (USGS V). Procedures for the preparation of acetylene gas used in the counting, and the method of counting, (two days in two separate counters) remain unchanged. However, the modern standard used is no longer wood grown in the 19th century, but 95% of the activity of NBS oxalic-acid radiocarbon standard, as recommended at the 1959 Groningen Radiocarbon Conference. Measurement of the oxalic-acid standard at our laboratory indicates 6.2 ± 1% more C14 activity than our modern wood standard; so use of the new standard should make no appreciable difference when comparing samples computed by the old method. W. F. Libby's (1955) half-life average for C14, 5568 ± 30 years, was used for the decay equation.
University of Michigan Radiocarbon Dates VI
Authors: Crane H. R. , Griffin James B.
Published: July 2016

The following is a list of radiocarbon dates obtained since the preparation of the manuscript for the publication of Michigan V, in December, 1959. The method of measurement and treatment of data are the same as those described in the introductions to Michigan lists III and IV. A full statement on the Michigan counter is referred to by Crane (p. 46) in this issue.
Inorganic Radiocarbon in Time-Series Sediment Trap Samples: Implication of Seasonal Variation of 14C in the Upper Ocean
Authors: Honda Makio C.
Published: July 2016

In order to verify sediment trap samples as indicators of upper ocean 14C concentrations, particulate inorganic radiocarbon (PICΔ14C) collected by time-series sediment traps in the Sea of Okhotsk and the Bering Sea was measured by accelerator mass spectrometry (AMS). All of the PICΔ14C measurements were < 0‰, in contrast to GEOSECS 14C data in the upper ocean from the northwestern North Pacific. This difference is attributed to the upwelling of deepwater that contains low Δ14C of dissolved inorganic carbon (DICΔ14C) and to the decrease over time of surface DICΔ14C owing to the decrease of atmospheric Δ14C values. In addition, PICΔ14C values showed significant seasonal variability: PICΔ14C collected in the fall was the greatest (-22‰ on average), whereas PICΔ14C collected in winter showed an average minimum of −48‰. It is likely that this difference was caused by changes in mixed layer thickness. Although some uncertainties remain, further study on PICΔ14C will enable us to estimate seasonal variability in DICΔ14C and air-sea CO2 exchange rate.
Radiocarbon Dating of Varve Chronologies: Soppensee and Holzmaar Lakes after Ten Years
Authors: Hajdas Irka , Bonani Georges , Zolitschka Bernd
Published: July 2016

During the last decade, several radiocarbon-dated varve chronologies have been produced. The main goal at first was the extension of the 14C calibration curve beyond 10,000 BP. This paper aims to discuss varve chronologies of Soppensee and Holzmaar Lakes. Although both chronologies encountered problems, high-resolution 14C dating and relative varve time have been obtained for events during the Late Glacial.
Comparison of U-Series and Radiocarbon Dates of Speleothems
Authors: Goslar Tomasz , Hercman Helena , Pazdur Anna
Published: July 2016

The paper presents a comparison of U-series and radiocarbon dates of speleothems collected in several caves in central and southern Europe and southeast Africa. Despite a large spread of dates, mainly due to contamination with younger carbon, the group of corresponding 14C and 230Th/U ages of speleothem samples seems to be coherent with the previous suggestion of large deviation between the 14C and the absolute time scale between 35 and 45 ka BP. This agrees with the result of frequency analysis of published 14C and 230Th/U ages of speleothem.
14C Calibration in the Southern Hemisphere and the Date of the Last Taupo Eruption: Evidence from Tree-Ring Sequences
Authors: Sparks R. J. , Melhuish W. H. , McKee J.W. A. , Ogden John , Palmer J. G. , Molloy B. P. J.
Published: July 2016

Tree rings from a section of Prumnopitys taxifolia (matai) covering the period ad 1335–1745 have been radiocarbon dated and used to generate a 14C calibration curve for southern hemisphere wood. Comparison of this curve with calibration data for northern hemisphere wood does not show a systematic difference between 14C ages measured in the northern and southern hemispheres. A floating chronology covering 270 yr and terminating at the last Taupo (New Zealand) eruption, derived from a sequence of 10-yr samples of tree rings from Phyllocladus trichomanoides (celery pine, or tanekaha), is also consistent with the absence of a systematic north-south difference, and together with the matai data, fixes the date of the Taupo eruption at ad 232 ± 15.
Radiocarbon-Dated Subfossil Stomach Oil Deposits from Petrel Nesting Sites: Novel Paleoenvironmental Records from Continental Antarctica
Authors: Hiller Achim , Hermichen Wolf-Dieter , Wand Ulrich
Published: July 2016

Radiocarbon dating is an important tool for reconstructing Late Quaternary paleoenvironmental history of the Antarctic continent. Because of the scarcity of datable material, new suitable substances are welcomed. We present here novel paleoenvironmental records—subfossil stomach oil deposits (mumiyo). This waxy organic material is found in petrel breeding colonies, especially in those of snow petrels, Pagodroma nivea. The substance is formed by accumulation and solidification of stomach oil regurgitated for the purpose of defense. We demonstrate and outline the usefulness and limitations of 14C dating mumiyo for determining dates of local ice retreat, moraines and petrel occupation history.
Dating Pictographs with Radiocarbon
Authors: Ilger Wayne , Hyman Marian , Southon John , Rowe Marvin
Published: July 2016

We report here progress on our technique for14C dating pictographs. We use low-temperature oxygen plasmas coupled with high-vacuum techniques to selectively remove carbon-containing material in the paints without contamination from rock substrates or accretions. We dated >16 pictograph samples that generally agree with ages expected on the basis of archaeological inference. We have shown that carbonate and calcium oxalate decomposition does not occur during our procedure; little mass fractionation is produced. We also used the technique on samples of known14C activity. In each case our results agree with previously determined ages of archaeological charcoal samples. Two samples of the standard Third International Radiocarbon Intercomparison wood yielded ages in near accord with the accepted value. We used14C-free samples to establish that the method and apparatus do not have a significant live carbon background. Each of these determinations supports our conclusion that the technique has the potential of producing accurate and reliable ages. However, background organic material in the basal rocks and accretions can be troublesome, often completely negating the dates obtained.
The Swedish Time Scale: A Potential Calibration Tool for the Radiocarbon Time Scale During the Late Weichselian
Authors: Wohlfarth Barbara , Björck Svante , Possnert Göran
Published: July 2016

The Swedish Time Scale (STS) is aca.13,300-yr-long varve chronology that has been established for the Swedish east coast from >1000 overlapping clay-varve diagrams. We describe the present state of the STS and illustrate the application of this worldwide unique varve chronology for AMS radiocarbon measurements. The results are compared to other14C-dated calendar-year chronologies: dendrochronology, laminated lake sediments and U/Th. Our data set agrees with the oldest part of the dendrochronological calibration curve, and with AMS14C-dated lake lamination data and U/Th on corals down toca.12 ka calendar years bp. Further back in time, the AMS-dated part of the STS partly compares well with lake lamination chronologies and shows that the difference between14C and calendar years decreases rapidly between 12,600 and 12,800 calendar years bp. Such a development seems to contrast with U/Th measurements on corals. We suggest that the cause for the divergence among three supposed calendar-year chronologies lies in the fact that the data points on the marine14C-U/Th curve are more widely spaced in time than the tightly grouped set of terrestrial AMS14C dates, and thus are not able to reflect short-term changes in atmospheric14C. Therefore, we argue that the use of the pre-Holocene part of the calibration program is premature and inadvisable.
Radiocarbon Calibration and Analysis of Stratigraphy: The OxCal Program
Authors: Bronk Ramsey Christopher
Published: July 2016

People usually study the chronologies of archaeological sites and geological sequences using many different kinds of evidence, taking into account calibrated radiocarbon dates, other dating methods and stratigraphic information. Many individual case studies demonstrate the value of using statistical methods to combine these different types of information. I have developed a computer program, OxCal, running under Windows 3.1 (for IBM PCs), that will perform both 14C calibration and calculate what extra information can be gained from stratigraphic evidence. The program can perform automatic wiggle matches and calculate probability distributions for samples in sequences and phases. The program is written in C++ and uses Bayesian statistics and Gibbs sampling for the calculations. The program is very easy to use, both for simple calibration and complex site analysis, and will produce graphical output from virtually any printer.
Atmospheric 14CO2 Variations in the Equatorial Region
Authors: Rozanski Kazimierz , Levin Ingeborg , Stock Jürgen , Guevara Falcon Raul E. , Rubio Fernando
Published: July 2016

We present here first results of 14CO2 monitoring at two sampling sites in the equatorial region of the South American continent (station Aychapicho, Ecuador and station Llano del Hato, Venezuela). We also include the data for two other stations representing undisturbed marine atmosphere at mid-latitudes of both hemispheres, far from large continental sources and sinks of CO2 (station Izaña, Tenerife, Spain and station Cape Grim, Tasmania). Between 1991 and 1993, 14CO2 levels in the tropical troposphere were generally higher by 2–5‰ when compared to mid-latitudes of both hemispheres. This apparent maximum of 14C in the tropics can be explained by two major factors: 1) emissions of 14C-free fossil fuel CO2, restricted mainly to mid-latitudes of the northern hemisphere; and 2) 14C depletion due to gas exchange with circumpolar Antarctic upwelling water, influencing mainly mid- and high southern latitudes. The δ14C record so far available for the Aychapicho station provides direct evidence for a regional reduction of atmospheric 14CO2 levels due to gas exchange with 14C-depleted equatorial surface ocean in the upwelling regions and dilution with the 14C-depleted CO2 released in these areas. Recurrent ENSO events, turning on and off the 14C-depleted CO2 source in the tropical Pacific, lead to relatively large temporal variations of the atmospheric 14C level in this region.
Regional Variability of Surface Ocean Radiocarbon from Southern Great Barrier Reef Corals
Authors: Druffel Ellen R. M. , Griffin Sheila
Published: July 2016

High-precision ∆14C and stable isotope (∆18O and ∆13C) records are reported for post-bomb corals from three sites off the eastern Australian coast. We observe that ∆14C values increased fromca.−50′ in the early 1950s to +130‰ by 1974, then decreased to 110‰ by 1991. There is general agreement between the coral results and ∆14C of dissolved inorganic carbon (DIC) in seawater measured previously for locations in the South Pacific. ∆14C values at our southern hemisphere sites increased at a slower rate than those observed previously in the northern hemisphere. Small variations in the ∆14C records among our three sites are likely due to differences in circulation between the shallow coastal waters and the open ocean influenced by seasonal upwelling. Low ∆14C is associated with most El Niño/Southern Oscillation (ENSO) events after 1970, indicating input of low14C waters from the southern-shifted South Equatorial Current. The exception is the severe ENSO event of 1982–1983 when upwelling in the South Equatorial Current could have ceased, causing normal ∆14C values in the corals during this time.
Origin of14C in Icelandic Groundwater
Authors: Sveinbjörnsdóttir Árný E. , Heinemeier Jan , Arnórsson Stefán
Published: July 2016

We report the first attempt to date Icelandic groundwater by the radiocarbon dating technique. We propose that boron concentrations of the water samples can be taken as a measure of the amount of dead CO2in the groundwater leached from rock. By assuming that the ratio of boron to CO2is the same in the rock and groundwater it is possible to correct the14C concentration for the contribution of rock-derived carbon in the groundwater and thus calculate the initial (undiluted)14C concentration. When this correction is applied, the values for the cold and warm waters lie in the range 60 to 110 pMC, which is in accordance with the estimated residence time for the groundwater. We have also calculated the fractions of atmospheric and organic carbon in the water, based on the δ13C measurements, and the results agree well with the general hydrology and vegetational cover of the areas. Results from geothermal systems indicate that it is possible to use14C to estimate relative age differences of the water in a particular geothermal area.
Radiocarbon Production by the Gamma-Ray Component of Supernova Explosions
Authors: Damon Paul E. , Kaimei Dai , Kocharov Grant E. , Mikheeva Irina B. , Peristykh Alexei N.
Published: July 2016

We selected SN1006, the brightest and closest to Earth of all supernovas historically observed, for a study of 14C production by e−,e+-bremsstrahlung cascades initiated by hard γ rays (>10 MeV) from that event. During the cascade, bremsstrahlung energies eventually fall within a giant (n,γ), (n,2γ) cross-section, peaking at 23 MeV and approaching effectively zero below 10 MeV and above 40 MeV. The neutrons are absorbed primarily in the reaction 14N(n,p)14C. Cellulose from single-year tree rings from ad 1003 to ad 1020 was measured to determine ∆14C. Three years after the first visual observation of SN1006, ∆14C rose and remained above pre-ad 1009 values until ad 1018. Comparison of the 7 years before ad 1009 with the 9 years following show an average increase of 6.1 ± 1.6 (s.d.)‰ (significant at the 99.6% confidence level). Such a pulse of 14C requires a total production of neutrons of 17.1 × 107n cm−2e, implying an input of 11.3 × 104 ergs cm−2e γ-ray energy. This requires the total supernova γ-ray energy (>10 MeV) to have been 1 × 1050 ergs.
A Single-Year δ13C Chronology from Pinus Tabulaeformis (Chinese Pine) Tree Rings at Huangling, China
Authors: Leavitt Steven W. , Yu Liu , Hughes Malcolm K. , Rongmo Liu , Zhisheng An , Gutierrez Graciela M. , Danzer Shelley R. , Xuemei Shao
Published: July 2016

Individual rings from 1899–1990 were pooled from four radii of four cross-sections obtained from trees at a managed forest site near Huangling, north of Xian in north central China. Splits of wood ground to 20-mesh were analyzed independently at both the Xian and Arizona laboratories, using their respective methods for cellulose isolation, combustion and mass-spectrometric analysis. The δ13C results were highly correlated (r2 = 0.66) and absolute values typically within 0.2–0.3‰. Inter-tree variability was estimated as 1–1.5‰. The Huangling δ13C curve shows an overall downward trend with year-to-year fluctuations of up to 1.5‰ superimposed. A subset of δ13C maxima corresponded with below-normal precipitation and above-normal temperature in May and June, and minima were associated with above-normal precipitation and below-normal temperature in May and June, perhaps signaling early arrival of the East Asian Summer Monsoon. The generally poor climate correlations with all δ13C values, however, could be a consequence of the fairly mesic environment or of human disturbance. Chronologies of isotopic discrimination (δ) and Ci/Ca had flat slopes, suggesting the δ13C trend was driven by global rather than local effects.
Radiocarbon Dating of Buried Trees and Climate Change in West-Central Oklahoma
Authors: Davis Owen K. , Kaimei Dai , Dean Jeffrey S. , Parks Jim , Kalin Robert M.
Published: July 2016

Eleven radiocarbon dates and tree-ring analyses of 3 juniper logs demonstrate the potential for 14C analysis of buried logs in the American Midwest. Three junipers (cf. Juniperus virginiana) were recovered from 9.20, 10.50, and 10.60 m in the fill of Carnegie Canyon, west-central Oklahoma. Their 14C ages are calibrated between 3300 and 2800 yr ago. A negative correlation of tree rings and ∆14C (p = 0.013) supports the findings of Schmidt and Gruhle (1988), who demonstrate the association of global cooling with reduced solar activity.
The Hvee 14C System at Groningen
Authors: Gottdang Andreas , Mous Dirk J. W. , Van Der Plicht Johannes
Published: July 2016

Since May 1994, a new-generation accelerator mass spectrometer (AMS) has been fully operational at the Centre for Isotope Research in Groningen, The Netherlands. The fully automated and high-throughput accelerator mass spectrometry (AMS) system, manufactured by High Voltage Engineering Europa (HVEE) is dedicated to radiocarbon analysis. The HVEE 4130 14C AMS is able to analyze up to 3000 samples per year. The system is characterized by simultaneous transport of all three isotopes (12C, 13C, 14C) and 14C analysis with a precision below 0.5 pMC and a daily stability below 0.5 pMC. We present here a system description together with stability and performance measurements.
Stability of a New, Multichannel, Low-Level Liquid Scintillation Counter System, Kvartett
Authors: Einarsson Sigurđur , Theodórsson Páll
Published: July 2016

Kvartett is a new liquid scintillation counting (LSC) system for radiocarbon dating that takes a radical departure from conventional systems to obtain a compact, low-level counting system measuring four samples simultaneously. Each sample vial, inside the well of a large NaI(Tl) guard-counter crystal (facing down), sits on top of a vertical PMT. The fourfold counting capacity can be used to increase the number of samples being dated or to get higher precision. The increased throughput helps to keep a rigid quality-control standard. We monitored the background count rate almost continuously for 7 months, and measured the count rate of a standard repeatedly for 2 months. The results show the background and system reproducibility to be stable.
A Data Acquisition System for Proportional Counters at Gliwice
Authors: Michczyński Adam , Goslar Tomasz , Pazdur Anna , Pazdur Mieczysław F.
Published: July 2016

We present here the principal ideas of a new, fully computerized data acquisition system with pulse-rise background reduction, developed in the Gliwice Radiocarbon Laboratory, and our first results. The new system uses a microprocessor-controlled pulse and coincidence analyzer for acquisition of data from 3 of 4 proportional counter sets. The analyzer acquires and stores information on the pulse's amplitudes and rise-times and their coincidence with guard counters and radio-frequency shield. This feature allows us to separate pulses using anticoincidence information and pulse-shape discrimination. The described method of background reduction led to a significant increase in the factor of merit on 2 of 3 counters tested.
A General Computer Program for Radiocarbon Dating Laboratories
Authors: González-Gómez Cecilio
Published: July 2016

Radiocarbon dating laboratories deal with many types of data and calculations, which include information on received and dated samples, age calculations and storage of results, printed reports to submitters and graphs plotted from sample measurements. I describe a computer program, designed to run on any PC-compatible computer with a hard disk, that can handle all the functions of a conventional liquid scintillation counting radiocarbon dating laboratory.
Suitability of Ostrich Eggshell for Radiocarbon Dating
Authors: Vogel John C , Visser Ebbie , Fuls Annemarie
Published: July 2016

Ostrich eggshell from archaeological sites remains largely free of more recent carbon contamination and as such is suitable material for radiocarbon dating. The carbonate fraction of the shell does, however, display an initial deficit in 14C, which causes the ages to appear 180 ± 120 yr too old.
Radiocarbon Dates from Paleolithic Sites in Korea
Authors: Bae Kidong
Published: July 2016

Fewer than 20 radiocarbon dates have been obtained from Paleolithic sites on the Korean Peninsula. It is still unknown how and when Korean Middle Paleolithic stone industries developed, despite the handful of dates older than 40,000 BP obtained from some sites. A lower boundary for the Korean Upper Paleolithic of approximately 30,000 BP can be inferred from the few dates associated with stone blade industries. 14C dates associated with microlithic industries of 24,000 BP are considered too old in light of evidence from other areas of East Asia. Most such assemblages are post-Last Glacial Maximum in age. Improved understanding of the Korean Paleolithic sequence will depend ultimately on the further accumulation of 14C dates, as well as the application of alternative dating techniques and attention to the reconstruction of site formation process.
Peopling of Western Japan, Focusing on Kyushu, Shikoku, and Ryukyu Archipelago
Authors: Takamiya Hiroto , Obata Hiromi
Published: July 2016

The discovery of the Iwajuku site in Japan is the beginning of the study of the first Paleolithic cultures in the region. In this paper we examine the timing of the earliest colonization of southern Japan, especially focusing on the areas of Kyushu, Shikoku, and the Ryukyu archipelago. Osteological studies have proposed the ultimate origin of these western Japanese Paleolithic populations in Southeast Asia. If this hypothesis is correct, Native Americans may be remotely related to the populations of this region. Greater attention to data from areas such as Japan is necessary to understand the timing and nature of New World colonization.
Rudjer Bošković Institute Radiocarbon Measurements XV
Authors: Obelić Bogomil , Krajcar Bronić Ines , Horvatinčić Nada
Published: July 2016

In this report we present dating of archaeological samples performed since 1995 in the Radiocarbon Laboratory of the Rudjer Bošković Institute. Several samples from the period before 1995, which were not included in our previous data lists, are given as well. Sample preparation, proportional counter technique, and processing of data are essentially the same as reported earlier (Srdoč et al. 1971, 1979; Obelić 1989). The quality assurance and quality control system according to ISO 17025 has been improved within the IAEA TC Regional Project on Quality Control and Quality Assurance for Nuclear Analytical Techniques. The laboratory participated in 14C intercomparison studies (Horvatinčić et al. 1990; Krajcar Bronić et al. 1995; Bryant et al. 2001; Radiocarbon 2001). We use Oxalic Acid I as modern standard, and anthracite and marble as background standards.
14C Dating of the ‘Titulus Crucis’
Authors: Bella Francesco , Azzi Carlo
Published: July 2016

The authors study the radiocarbon dating of a relic believed to be the tablet that was placed on the cross of Jesus Christ at the time of his crucifixion.
The Antiquity of Pearl Shell (Pinctada Sp.) Burial Artifacts in Palau, Western Micronesia
Authors: Fitzpatrick Scott M , Boyle Jenna E
Published: July 2016

Pearl shell was an important and highly valued resource for producing tools and ornaments in Oceania. One pearl shell artifact type that is quite rare in Micronesia, however, is the crescent-shaped scraper/grater. These artifacts have recently been found in 2 burial caves in Palau, Western Caroline Islands, suggesting they may have played important social and symbolic roles in society. The first direct accelerator mass spectrometry (AMS) dating of this tool type, found in association with an in-situ female burial at the Chelechol ra Orrak site, provides a date of AD 150–270, while associated dates range from 770 BC–AD 180. These dates help contextualize human burials and associated artifacts from one of the earliest and most diverse burial sites in Austronesia.
The Radiocarbon Dating and Authentication of Iron Artifacts
Authors: Craddock P T , Wayman M L , Jull A J T
Published: July 2016

The continuing improvements in accelerator mass spectrometry (AMS) dating technology mean that it is possible to work on ever smaller samples, which in turn, make an ever wider range of sample potentially available for dating. This paper discusses some of the difficulties arising with the interpretation of AMS dates obtained from carbon in iron. The overriding problem is that the carbon, now in chemical combination with the iron, could have come from a variety of sources with very different origins. These are now potentially an iressolvable mixture in the iron. For iron made over the last millennium, there are the additional problems associated with the use of both fossil fuel and biomass fuel in different stages of the iron making, leading to great confusion, especially with authenticity studies.