• 14C AMS Measurements of <100 Microgram Samples with a High-Current System

      von Reden, K. F.; McNichol, Ann P.; Pearson, Ann; Schneider, Robert J. (Department of Geosciences, The University of Arizona, 1998-01-01)
      The NOSAMS facility at Woods Hole Oceanographic Institution has started to develop and apply techniques for measuring very small samples on a standard Tandetron accelerator mass spectrometry (AMS) system with high-current hemispherical Cs sputter ion sources. Over the past year, results on samples ranging from 7 to 160 micrograms C showed both the feasibility of such analyses and the present limitations on reducing the size of solid carbon samples. One of the main factors affecting the AMS results is the dependence of a number of the beam optics parameters on the extracted ion beam current. The extracted currents range from 0.5 to 10 micro-A of 12Cfor the sample sizes given above. We here discuss the setup of the AMS system and methods for reliable small-sample measurements and give the AMS-related limits to sample size and the measurement uncertainties.
    • 14C Analyses of Groundwater from the Botucatu Aquifer System in Brazil

      Silva, Annkarin Aurelia Kimmelmann E.; da Cunha Rebouças, Aldo; Freitas Santiago, Maria Marlucia (Department of Geosciences, The University of Arizona, 1989-01-01)
      Measurements of 14C activity as well as determinations of the stable isotope composition (18O, 2H and 13C) of groundwater samples were made to investigate the flow path, origin, recharge and age of the Botucatu Aquifer System in Brazil, between 1984 and 1987. The stable oxygen isotope composition reflects infiltration during several climatic recharge conditions. Measured 14C activities range from 0.4 to 94.2% modern. delta-13C values enable us to distinguish two groundwater types of different origins. There is a gradual increase of 14C ages from the outcrop area towards the central part of the basin, associated with a progression of the confining conditions. Anomalous fluoride contents seem to be correlated with high 14C ages of the groundwater. The reliability of the 14C data is discussed.
    • 14C Analysis of Annual Tree Rings from the Vicinity of the Chernobyl NPP

      Buzinny, Michael; Likhtarev, Ilja; Los', Ivan; Talerko, Nikolay; Tsigankov, Nikolay (Department of Geosciences, The University of Arizona, 1998-01-01)
      Samples of >40 pine trees were collected from around the Chernobyl NPP for radiocarbon measurement, to determine the spatial distribution of excessive 14C in tree rings from 1986 consequent upon accidental radiocarbon release. Tree samples were collected during 1995-1996 from sites situated at distances >2.5 km from the NPP and covering a variety of directions in relation to the NPP. To evaluate Delta-14C for 1986 annual rings, we compared 14C levels for separate 1985-1987 annual rings, taking into account the trend of operational releases. Early and late wood samples for 1986 annual tree rings were measured separately to increase the sensitivity and precision of measurements. The maximum value observed for excessive accidental radiocarbon levels (Delta-14C) was found to be 124 pMC (281.6 Bq kg-1 C). We present Delta-14C values for examined sites; their spatial distribution shows a high irregularity of atmospheric 14C depending on direction from the NPP. Using obtained data, we reconstruct the temporal behavior of 14C release during the Chernobyl accident with the aid of atmospheric transport modeling. The total amount of 14C released from 26 April to 5 May 1986 has been estimated as 44 TBq.
    • 14C and 18O in Siberian Syngenetic Ice-Wedge Complexes

      Vasil'chuk, Y. K.; Vasil'chuk, A. C. (Department of Geosciences, The University of Arizona, 1998-01-01)
      We discuss the possibility of dating ice wedges by the radiocarbon method. We show as an example the Seyaha, Kular and Zelyony Mys ice wedge complexes, and investigated various organic materials from permafrost sediments. We show that the reliability of dating 18O variations from ice wedges can be evaluated by comparison of different organic materials from host sediments in the ice wedge cross sections.
    • 14C and 234U-Excess Dating of Groundwater in the Haifa Bay Region, Israel

      Rogojin, Vasily; Carmi, Israel; Kronfeld, Joel (Department of Geosciences, The University of Arizona, 1998-01-01)
      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.
    • 14C and Other Parameters During the Younger Dryas Cold Phase

      Oeschger, Hans; Welten, Max; Eicher, Ulrich; Möll, Markus; Riesen, Trudi; Siegenthaler, Ulrich; Wegmüller, Samuel (American Journal of Science, 1980-01-01)
      Pollen analysis as well as 18O/16O results on lake marl show that the Younger Dryas climatic period, between about 11,000 and 10,300 BP, was the last vigorous cold phase of the Wurm Glacial. Detailed 14C analyses from a peat bog near Wachseldorn (Switzerland) point to a 14C anomaly in this period. Further indication of a 14C anomaly is given by the observation that, during the Younger Dryas period, the sedimentation rates in several lakes apparently were higher than in adjacent periods; an explanation might be that the 14C time scale was compressed between 11,000 and 10,000 BP, ie, the atmospheric 14C/C ratio varied. If real, this suggested 14C variation would probably be connected to the climatic events during this transition period from Later Glacial to Postglacial.
    • 14C and the Iron Age Chronology Debate: Rehov, Khirbet En-Nahas, Dan, and Megiddo

      Finkelstein, Israel; Piasetzky, Eli (Department of Geosciences, The University of Arizona, 2006-01-01)
      A recently published volume, the Bible and Radiocarbon Dating: Archaeology, Text and Science (Levy and Higham 2005), provides data related to the debate over the chronology of the Iron Age strata in the Levant (for a review, see Carmi 2006). The present article comments on several chapters in the volume. The article highlights methodological problems, such as insecure stratigraphic provenance of 14C samples, and demonstrates how unjustified selection of data can bias the result. The article offers a new interpretation to some of the results and shows that the full set of measurements from Tel Rehov supports the Low Chronology system.
    • 14C Background Levels in an Accelerator Mass Spectrometry System

      Vogel, J. S.; Nelson, D. E.; Southon, J. R. (American Journal of Science, 1987-01-01)
      The levels and sources of the measurement background in an AMS 14C dating system have been studied in detail. The relative contributions to the total background from combustion, graphitization, storage, handling, and from the accelerator were determined by measuring the 14C concentrations in samples of anthracite coal ranging in size from 15 micrograms to 20mg. The results show that, for the present system, the uncertainty in the background is greater than that due to measurement precision alone for very old or for very small samples. While samples containing 100 micrograms of carbon can yield useful 14C dates throughout the Holocene, 200 to 500 micrograms are required for dating late Pleistocene materials. With the identification of the procedures that introduce contamination, the level and uncertainty of the total system background should both be reducible to the point that 100 micrograms of carbon would be sufficient for dating most materials.
    • 14C Calibration Curves for Modern Plant Material from Tropical Regions of South America

      Ehleringer, James R.; Casale, John F.; Barnette, Janet E.; Xu, Xiaomei; Lott, Michael J.; Hurley, Janet (Department of Geosciences, The University of Arizona, 2011-12-16)
      Two 14C calibration curves have been produced that allow determination of the statistical average age of coca leaf and cocaine base specimens produced for the time period 19792009. These calibration curves are based on field collections of specimens in Bolivia, Colombia, Ecuador, and Peru. The coca leaf F14C and 14C calibration curves can be used to predict the ages of botanical tissues collected in tropical South America and possibly extended to other tropical locations. The cocaine F14C and 14C calibration curves can be used to predict the ages of seized cocaine specimens. Because the 14C of the atmosphere is diminishing, the precision of this approach for age determinations will continue to get less precise over time as atmospheric 14C content continues to decline.
    • 14C Calibration in the 2nd and 1st Millennia BC—Eastern Mediterranean Radiocarbon Comparison Project (EMRCP)

      Kromer, Bernd; Manning, Sturt W.; Friedrich, Michael; Talamo, Sahra; Trano, Nicole (Department of Geosciences, The University of Arizona, 2010-01-01)
      We have measured additional known-age German oak samples in 4 intervals in the 2nd and 1st millennia BC to add to (and to replicate) parts of the international Northern Hemisphere radiocarbon calibration data set. In the 17th, 16th, and 12th centuries BC, our results agree well with IntCal04. In the 14th and 13th centuries BC, however, we observe a significant offset, with our results on average 27 yr older than IntCal04. The previously reported 14C offset between Anatolian juniper trees and central European oaks in the 9th and 8th centuries BC is smaller now, on the basis of our new measurements of German oak, but still evident. In the 17th and 16th centuries BC, the 14C ages from the Anatolian chronology agree well with IntCal04 and our new German oak data.
    • 14C Calibration in the Southern Hemisphere and the Date of the Last Taupo Eruption: Evidence from Tree-Ring Sequences

      Sparks, R. J.; Melhuish, W. H.; McKee, J. W. A.; Ogden, John; Palmer, J. G.; Molloy, B. J. (Department of Geosciences, The University of Arizona, 1995-01-01)
      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.
    • 14C Chronology of Archaeological Sites in European Russia and Changes in Environmental Processes: A Database Investigation

      Zaitseva, Ganna I.; Dergachev, Valentin A.; Timofeev, Vladimir; Sementsov, Anatoly A. (Department of Geosciences, The University of Arizona, 1998-01-01)
      A large number of 14C dates for archaeological sites in European Russia have been entered into a new database. The database includes >1500 dates for ca. 500 archaeological sites. Because European Russia is a very large area, the database includes subdivisions of territories and regions. We analyzed our 14C dates according to archaeological periods (Paleolithic through Medieval period) and made a comparison with environmental (climatic) parameters. Our database for archaeological sites and monuments offers new possibilities for correlation between the development of ancient cultures and natural-climatic processes.
    • 14C Chronology of Avellino Pumices Eruption and Timing of Human Reoccupation of the Devastated Region

      Passariello, Isabella; Livadie, Claude Albore; Talamo, Pierfrancesco; Lubritto, Carmine; D'Onofrio, Antonio; Terrasi, Filippo (Department of Geosciences, The University of Arizona, 2009-01-01)
      The Avellino Pumices eruption was one of the most catastrophic volcanic events of Somma-Vesuvius, which hit prehistoric communities during the Early Bronze Age. In the last 30 yr, several authors reported assessments about its chronology, including radiocarbon datings, but with poor internal agreement and frequently with large experimental errors. A new and more accurate 14C dating of this eruption (1935-1880 BC, 1 sigma) was obtained at the CIRCE laboratory in Caserta (Italy) by 3 AMS measurements on a bone sample of a goat buried by the eruption, collected in an Early Bronze Age village at Croce del Papa (Nola, Naples). These results were verified by other measurements on several samples chronologically related to the eruption. Our data show that human resettlement after the eruption occurred rather quickly but lasted only for a short time in areas affected by the volcanic products, like Masseria Rossa and San Paolo Belsito (Nola, Naples), according to 14C dating of archaeological samples collected below and above the eruption deposits. The state-of-the-art chronology of this eruption, emerging from the results obtained in this work as well as from data in the literature, is discussed.
    • 14C Chronology of Burial Grounds of the Andronovo Period (Middle Bronze Age) in Baraba Forest Steppe, Western Siberia

      Molodin, V. I.; Marchenko, Z. V.; Kuzmin, Y. V.; Grishin, A. E.; Van Strydonck, M.; Orlova, L. A. (Department of Geosciences, The University of Arizona, 2012-10-15)
      This paper focuses on the chronology of Middle Bronze Age complexes in the Baraba forest steppe (western Siberia). Three sites were radiocarbon dated, Stary Tartas 4, Sopka 2, and Tartas 1. The Late Krotovo culture was dated to the 18–19th centuries BC, the Andronovo complex (Fedorovo stage) to the 15–18th centuries BC, and the Mixed Andronovo complex dated to the 15–17th centuries BC. These values are some 300–500 yr older than previously thought, and the new results are consistent with 14C dates of the Andronovo cultural complex in northern Eurasia. Based on these data, the 15th century BC is the upper chronological limit of the Andronovo period.
    • 14C Chronology of Late Pleistocene-Holocene Events in the Nizhnee Priamurie (Southeast Russia)

      Bazarova, V. B.; Mokhova, L. M.; Orlova, L. A.; Klimin, M. A.; Gvozdeva, I. G. (Department of Geosciences, The University of Arizona, 2003-01-01)
      The Russian Far East is characterized by widespread peat bogs with a sufficiently thick peat accumulation. A series of radiocarbon dates from the studied peat bogs (in Lower Amur) were obtained. Analysis of these dates shows that the total peat formation in this territory began in the Late Pleistocene-Holocene (11,830 +/820, TIG-157; 9975 +/120, SOAN-4025). The rates of peat accumulation and the humidity index were counted. In addition, the botanical composition and degree of peat decomposition were defined. These data allow to study in more detail climate fluctuation and the 14C chronology of Holocene events in the region studied.
    • 14C Chronology of Mesolithic Sites from Poland and the Background of Environmental Changes

      Pazdur, Anna; Fogtman, Mariusz; Michczyński, Adam; Pawlyta, Jacek; Zając, Mirosław (Department of Geosciences, The University of Arizona, 2004-01-01)
      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 Calowanie. 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.
    • 14C Chronology of Stone Age Cultures in the Russian Far East

      Kuzmin, Yaroslav V.; Jull, A. J. T.; Orlova, Lyobov A.; Sulerzhitsky, Leopold D. (Department of Geosciences, The University of Arizona, 1998-01-01)
      Ca. 150 unequivocal 14C dates from the prehistoric cultures in the Russian Far East can be used to elucidate chrono-cultural boundaries in that region. Microblade technology started as early as ca. 20,000 BP, and continued to exist in the middle Amur River basin until ca. 10,500 BP, and in Primorye until ca. 7800 BP. The emergence of pottery-making in the lower Amur River basin goes back to ca. 13,300 BP. The transition from Upper Paleolithic to Neolithic took place during the time interval 13,300-7800 BP and pottery was widely spread in the Russian Far East by ca. 6700-8400 BP. The first evidence of shellfish collection is estimated to ca. 6400 BP at Peter the Great Gulf coast, Sea of Japan. The beginning of agriculture in Primorye, based on finding of both millet seeds (Setaria italica L.) and pollen of cultivated cereals (Cerealia), is 14C-dated to ca. 4200-3700 BP (ca. 1980-2900 cal BC). The Neolithic/Early Iron Age boundary was estimated at ca. 3100-3300 BP (1400-1600 cal BC) in the mainland Russian Far East, and to ca. 1800-2300 BP (400 cal BC-200 cal AD) on the Sakhalin and southern Kuril Islands.
    • 14C Concentrations of Single-Year Tree Rings from About 22,000 Years Ago Obtained Using a Highly Accurate Measuring Method

      Kato, Katoh Wataru; Takahash, Takahashi Yousuke; Gunj, Gunji Syuichi; Tokana, Tokanai Fuyuki; Matsuzak, Matsuzaki Hiroyuki (Department of Geosciences, The University of Arizona, 2004-01-01)
      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.
    • 14C Cycle in the Hot Zone Around Chernobyl

      Kovaliukh, Nikolai N.; Skripkin, Vadim V.; van der Plicht, Johannes (Department of Geosciences, The University of Arizona, 1998-01-01)
      Radiocarbon from the Chernobyl accident was released mainly in two forms: fine dispersed reactor graphite, and carbon dioxide from burning graphite. The CO2 was partly assimilated by annual and perennial vegetation. Reactor graphite dispersed over a wide territory was taken up biochemically by micromicetes, transforming non-organic carbon of the reactor graphite into organic matter. Organic matter of micromicetes is the main nutrition product for soil organisms such as bacteria, worms, larvae of insects, small beetles, etc. The following relatively independent trophic chains are considered: 1. Carbon dioxide —> leaves, grass —> insects; 2. Graphite —> micromicetes, protozoa, insects. The 14C content in beetles of different species sampled in the 30-km hot zone of the Chernobyl accident site in 1986-1988 agrees well with the contamination levels of insect habitats as well as with their biology.
    • 14C Database and Geographic Information System for Western Siberia

      Orlova, Lyobov A.; Kuzmin, Yaroslav V.; Zolnikov, Ivan D. (Department of Geosciences, The University of Arizona, 1998-01-01)
      We illustrate here the combined use of geographic information system (GIS) technology and a radiocarbon database for analysis of the environmental components and ancient sites in Western Siberia during the period 10-45 ka BP. In total, 230 14C dates from 75 Late Pleistocene outcrops and Paleolithic sites were used to generate paleolandscape maps and to establish the features of the spatiotemporal distribution of Paleolithic sites.