• Sponsors

      Department of Geosciences, The University of Arizona, 2004-01-01
    • International Advisory Board, New Zealand Organizing Committee, and Editorial Board

      Department of Geosciences, The University of Arizona, 2004-01-01
    • From the Guest Editors

      Sparks, Roger J.; Athfield, Nancy Beavan (Department of Geosciences, The University of Arizona, 2004-01-01)
    • Conference Participants

      Department of Geosciences, The University of Arizona, 2004-01-01
    • Chronology of Prehistoric Cultural Complexes of Sakhalin Island (Russian Far East)

      Kuzmin, Yaroslav V.; Vasilevski, Alexander A.; Gorbunov, Sergei V.; Burr, G. S.; Jull, A. J. Timothy; Orlova, Lyobov A.; Shubina, Olga A. (Department of Geosciences, The University of Arizona, 2004-01-01)
      A chronological framework for the prehistoric cultural complexes of Sakhalin Island is presented based on 160 radiocarbon dates from 74 sites. The earliest 14C-dated site, Ogonki 5, corresponds to the Upper Paleolithic, about 19,500-17,800 BP. According to the 14C data, since about 8800 BP, there is a continuous sequence of Neolithic, Early Iron Age, and Medieval complexes. The Neolithic existed during approximately 8800-2800 BP. Transitional Neolithic-Early Iron Age complexes are dated to about 2800-2300 BP. The Early Iron Age may be dated to about 2500-1300 BP. The Middle Ages period is dated to approximately 1300-300 BP (VII-XVII centuries AD).
    • Using a Gas Ion Source for Radiocarbon AMS and GC-AMS

      Bronk Ramsey, Christopher; Ditchfield, Peter; Humm, Martin (Department of Geosciences, The University of Arizona, 2004-01-01)
      This paper reports on the performance of a new method of sample injection using the High Voltage Engineering Europa (HVEE) SO-110 ion source jointly developed between HVEE and Oxford. In order to use this source, we have developed a new gas handling system which works on the direct injection of carbon dioxide mixed into a continuous flow of helium. Preliminary work has also been carried out on online gas chromatography-accelerator mass spectrometry (GC-AMS). In this application, a GC is directly coupled to the AMS system using a GC-IRMS combustion interface and Nafion(TM) drier. We show here results for the measurement of natural abundance in separated compounds with good peak separation and precisions of about 10%. This type of system should be ideal for source apportionment studies, biomedical, and other similar work where high precision is not required but where sample sizes are very low.
    • Towards Achieving Low Background Levels in Routine Dating by Liquid Scintillation Spectrometry

      Hogg, Alan G. (Department of Geosciences, The University of Arizona, 2004-01-01)
      International radiocarbon intercalibration studies have revealed that radiometric laboratories using liquid scintillation (LS) spectrometry of benzene reported, on average, younger ages for near-background standards than either gas proportional counter (GPC) or accelerator mass spectrometry (AMS) laboratories. These studies suggested that the younger LS ages are probably related to the use of spectrophotometric benzene as a background standard. An analysis of successive 110-ka subfossil wood (Airedale Reef Ancient Wood: ARAW) standards shows that vacuum line memory effects occur in LS spectrometry and, consequently, must be corrected to obtain accurate 14C dates. ARAW standards, measured at monthly intervals in the Waikato laboratory, are used to provide blank corrections for both research and routine dating applications. The strong correlation between the ARAW Delta-14C data and the sample activities that preceded the standards may provide an opportunity to obtain sample-specific blank correlations. Lithium carbide synthesis is likely to prove a source of contamination. This work suggests that reproducible background levels for routine dating of less than 0.1 pMC (55 ka 14C yr) are achievable.
    • Towards High-Precision AMS: Progress and Limitations

      Bronk Ramsey, Christopher; Higham, Thomas; Leach, Philip (Department of Geosciences, The University of Arizona, 2004-01-01)
      Precision and accuracy in accelerator mass spectrometry (AMS) dating relies on the systematic reduction of errors at all stages of the dating process, from sampling to AMS measurement. With new AMS systems providing much better precision and accuracy for the final stage of the process, we need to review the process as a whole to test the accuracy of reported results. A new High Voltage Engineering Europa (HVEE) AMS system was accepted at Oxford in September 2002. Since then, the system has been in routine use for AMS dating and here we report on our experiences during the first year. The AMS system itself is known to be capable of making measurements on single targets to a precision of better than 0.2% for the 14C/13C ratio and better than 0.1% for the 13C/12C ratio. In routine operation, we measure known-age wood to a precision of just above 0.3%, including uncertainties in background and pretreatment. At these levels, the scatter in results is no higher than reported errors, suggesting that uncertainties of +/25 to +/30 14C yr can be reliably reported on single target measurements. This provides a test of all parts of the process for a particular material in a particular state of preservation. More generally, sample pretreatment should remove as much contamination as feasible from the sample while adding as little laboratory contamination as possible. For more complex materials, such as bone, there is clearly more work needed to prove good reproducibility and insignificant offsets in all circumstances. Strategies for testing accuracy and precision on unknown material are discussed here, as well as the possibilities of one day reaching precisions equivalent to errors of < +/20 14C yr.
    • The New 14C Analysis Laboratory in Jena, Germany

      Steinhof, A.; Adamiec, G.; Gleixner, G.; van Klinken, G. J.; Wagner, T. (Department of Geosciences, The University of Arizona, 2004-01-01)
      The new accelerator mass spectrometry (AMS) Radiocarbon Analysis Laboratory in Jena is described. The laboratory developed a combustion system for solid samples and a CO2 extraction system for air samples. Thus far, sample preparation, including graphitization, was performed in the laboratory, and the samples were measured subsequently by other AMS facilities. Currently, the laboratory owns a 3MV AMS system from HVEE (Netherlands) that has passed the acceptance tests and will be used for routine 14C determinations in the near future. The AMS system is equipped with 2 ion sources, one suitable for graphite targets and the second for both graphite and CO2 targets.
    • The Keck Carbon Cycle AMS Laboratory, University of California, Irvine: Initial Operation and Background Surprise

      Southon, John; Santos, Guaciara; Druffel-Rodriguez, Kevin; Druffel, Ellen; Trumbore, Sue; Xu, Xiaomei; Griffin, Sheila; Ali, Shahla; Mazon, Maya (Department of Geosciences, The University of Arizona, 2004-01-01)
      A new radiocarbon accelerator mass spectrometry (AMS) laboratory for carbon cycle studies has been established at the University of California, Irvine. The 0.5MV AMS system was installed in mid-2002 and has operated routinely since October of that year. This paper briefly describes the spectrometer and summarizes lessons learned during the first year of operation. In the process of setting up the system, we identified and largely suppressed a previously unreported 14C AMS background: charge exchange tails from 14N beams derived from nitrogen-containing molecular ions produced near the entrance of the accelerator.
    • The End of the Chalcolithic Period in the South Jordan Valley: New 14C Determinations from Teleilat Ghassul, Jordan

      Bourke, Stephen; Zoppi, Ugo; Meadows, John; Hua, Quan; Gibbins, Samantha (Department of Geosciences, The University of Arizona, 2004-01-01)
      This article reports on 12 new accelerator mass spectrometry (AMS) dates from the latest phases of the Chalcolithic period occupation (late 5th millennium cal BC) at Teleilat Ghassul, type site for the south Levantine Ghassulian Chalcolithic culture. The new AMS dates from Teleilat Ghassul favor an amendment to a previous suggestion (Bourke et al. 2001), that all significant occupation at the site had ceased by 4000/3900 cal BC. This end-date should now be amended to 3900/3800 cal BC. Follow-up statistical modelling sourced to published 14C data drawn from a wide selection of south Levantine Chalcolithic period sites (Bourke 2001; Burton and Levy 2001) raises the possibility that Chalcolithic period occupation had ceased at virtually all major centers by 3800/3700 cal BC. This, in turn, suggests that the new data bearing on the end-date for occupation at Teleilat Ghassul may reflect a more widespread horizon of abandonment in the southern Levant.
    • Temporal Variation of Radiocarbon Concentration in Airborne Particulate Matter in Tokyo

      Shibata, Ken; Yamamoto, Naomichi; Endo, Michio; Yoshinaga, Jun; Yanagisawa, Yukio; Endo, Osamu; Goto, Sumio; Yoneda, Minoru; Shibata, Yasuyuki; Morita, Masatoshi (Department of Geosciences, The University of Arizona, 2004-01-01)
      The temporal radiocarbon variation (in terms of percent Modern Carbon: pMC) of size-fractionated airborne particulate matter (APM) collected in Tokyo between April 2002 and February 2003 was analyzed in order to get an insight into the sources of carbonaceous particles. Results indicated significant biogenic origins (approximately 40 pMC on average). In general, the seasonal and particle size variations in pMC were relatively small, with 2 exceptions: elevated pMC in coarse particles in April and October 2002, and relatively low pMC in the finest particle size fraction collected in August 2002. The former finding could be tentatively attributed to the abundance of coarse particles of biological origins, such as pollen; the latter might be due to an increased fraction of anthropogenic secondary particles.
    • Surface and Underground Ultra Low-Level Liquid Scintillation Spectrometry

      Plastino, Wolfango; Kaihola, Lauri (Department of Geosciences, The University of Arizona, 2004-01-01)
      Cosmic background and its variation have been removed in the Gran Sasso National Laboratory (National Institute of Nuclear Physics) by its 1400-m rock overburden. Stable, high-performance liquid scintillation counting conditions are obtained when any remaining variable components of the environmental background, such as radon, are eliminated. The ultra low-level liquid scintillation spectrometer Quantulus(TM) has an anti-Compton guard detector (guard for short) that allows monitoring of gamma radiation in the background. The guard detector efficiency in radiocarbon background reduction is 8% in the Gran Sasso National Laboratory, while 80% is observed in surface laboratories. Thus, atmospheric pressure variations in surface laboratories cause variation in cosmic radiation flux. The Quantulus anti-Compton detector is highly efficient in detecting cosmic radiation, and the sample count rate remains stable in long-term counting. Also, correlation of sample backgrounds with environmental gamma radiation in various laboratories is examined.
    • Simulation Study for the Separation of Rare Isotopes at the Seoul National University AMS Facility

      Yun, C. C.; Lee, C. S.; Youn, M.; Kim, J. C. (Department of Geosciences, The University of Arizona, 2004-01-01)
      A simulation study for the separation of rare isotopes such as beryllium and aluminum was performed for a new beam line to be attached to the 3MV Tandetron accelerator at the accelerator mass spectrometry (AMS) facility of Seoul National University in Korea. The new beam line will also be used for other scientific applications, namely, ion implantations, Rutherford backscattering, and nuclear astrophysics experiments. It mainly consists of 30 degrees and 100 degrees deflection dipole magnets and drift spaces. A transfer matrix for the beam line was determined by the TRANSPORT code. Simulation of the rare isotope separation was performed by a ray tracing method using the TURTLE code. The simulation results, including the effect of the energy degrader, provide feasibility for the separation of isobars with small mass differences in 10Be10B and 26Al-26Mg.
    • Source Apportionment of Aerosols by 14C Measurements in Different Carbonaceous Particle Fractions

      Szidat, S.; Jenk, T. M.; Gäggeler, H. W.; Synal, H.-A.; Fisseha, R.; Baltensperger, U.; Kalberer, K.; Samburova, V.; Wacker, L.; Saurer, M.; et al. (Department of Geosciences, The University of Arizona, 2004-01-01)
      Radiocarbon enables a distinction between contemporary and fossil carbon, which can be used for the apportionment of biogenic and anthropogenic sources in environmental studies. In order to apply this approach to carbonaceous atmospheric aerosols, it is necessary to adapt pretreatment procedures to the requirements of 14C measurements. In this work, we followed an approach in which total carbon (TC) is subdivided into fractions of different chemical and physical properties. 14C data of ambient aerosols from Zrich (Switzerland) are presented for the 2 sub-fractions of TC, organic carbon (OC) and elemental carbon (EC). Furthermore, OC is separated into water-insoluble OC (WINSOC) and water-soluble OC (WSOC). Results demonstrate the importance to differentiate between these fractions for 14C-deduced source apportionment, as the contributions can range between both extremes, nearly exclusively biogenic and anthropogenic.
    • Rehabilitation of the Laboratoire de Carbone 14-Dakar (Senegal) with a Super Low-Level Liquid Scintillation Counting System

      Ndeye, Maurice; Ka, Oumar; Bocoum, Hamady; Diallo, Alpha O. (Department of Geosciences, The University of Arizona, 2004-01-01)
      Following the passing of Prof Cheikh Anta Diop in 1986, the radiocarbon laboratory (LC14) he created 20 yr earlier at the Institut Francophone d'Afrique Noire (IFAN), Dakar, Senegal, fell into a long hibernation. It took nearly 3 yr to renovate the laboratory and reinstall new equipment in order to return LC14 to full functionality and resume its activity. A new dating system has been implemented around a super low-level liquid scintillation spectrometer from Packard, the Tri-Carb 3170TR/LS, located in an underground room. In this paper, we assess the performance of the dating setup (background level and figure of merit) using known samples from Paris 6 and international standards from the International Atomic Energy Agency (IAEA). After the calibration, the setup was used to study bole seashells from the Khant area in the northern part of Senegal (West Africa). The aim is to present evidence of the correlation between the transgression of the Nouakchottan (5500 BP) and a few industries in the Khant area. The corresponding ages are difficult to assess and the dates available for this cultural site are randomly distributed, ranging from 4500 to 1500 BP, i.e., a chronological period spanning from the Neolithic to the Iron Age.
    • Radiocarbon Dating of Kohitsugire (Paper Fragments) Attributed to Japanese Calligraphists in the Heian–Kamakura Period

      Oda, Hirotaka; Ikeda, Kazuomi; Matsuda, Takashi; Nakamura, Toshio (Department of Geosciences, The University of Arizona, 2004-01-01)
      A kohitsugire is a paper fragment from an old manuscript written mainly in the Heian and Kamakura periods. Although they contain significant information for historical, literary, and paleographical study, because of their antique handwriting and description of historical incidents, there are many copies and counterfeits written several centuries later. In this study, radiocarbon ages of kohitsugire were measured by accelerator mass spectrometry (AMS). On the kohitsugire attributed to the famous calligraphists in the Kamakura period (Fujiwara no Sadaie and Prince Munetaka), 14C dating indicated that they were not genuine and should be excluded from the materials for study of the calligraphists. Calibrated 14C ages of the kohitsugire attributed to Fujiwara no Yukinari indicated the middle Heian period. This calligraphy was written on Tobikumogami paper, which has a billowing cloud pattern decorated with indigo-blue-dyed fiber. Although it was commonly accepted that the Tobikumogami is peculiar to the middle 11th to early 12th century, the results from 14C dating also suggested that the origin of the Tobikumogami would date back to the last of the 10th or the early 11th century, when Fujiwara no Yukinari flourished as a calligraphist. Calibrated 14C ages of the kohitsugire attributed to Nijo Tameuji and Reizei Tamesuke showed that they are fragments of old manuscripts describing lost tales and were written in the 13th14th century. Consequently, 14C dating clarified the existence of ancient tales which had been unknown and indicated their worth as a material for the study of classical Japanese literature.
    • Radiocarbon Dating of Sopot Culture Sites (Late Neolithic) in Eastern Croatia

      Obelić, Bogomil; Škrivanko Krznarić, Marija; Marijan, Boško; Krajcar Bronić, Ines (Department of Geosciences, The University of Arizona, 2004-01-01)
      The results of radiocarbon dating of several Late Neolithic archaeological sites in Slavonia, eastern Croatia, are presented. According to the archaeological findings, the sites belong to the Sopot culture. Stages I-B, II-A, II-B, and III were identified at the eponym site Sopot near Vinkovci, stages I-B and II at the site Dubovo-Košno near Županja, while findings for other investigated sites (Herrmanns Vineyard near Osijek, Mandeks Vineyard from Otok, Privlaka near Vinkovci, and Slavča near Nova Gradiška) were placed to phases II and III. 14C results place the I-B stage to the period 5480-5070 cal BC, stage II-A to 5030-4770 cal BC, stage II-B to 4800-4250 cal BC, and phase III to 4340-3790 cal BC. These dates were compared to those obtained for other Late Neolithic cultures in the Pannonian Valley. The results confirmed the Protolengyel character of Sopot culture.
    • Radiocarbon Dating of Iron Artifacts at the Erlangen AMS Facility

      Scharf, Andreas; Kretschmer, Wolfgang; Morgenroth, Gerhard; Uhl, Thomas; Kritzler, Karin; Hunger, Katja; Pernicka, Ernst (Department of Geosciences, The University of Arizona, 2004-01-01)
      One problem in preparing iron for radiocarbon dating is the low carbon content which makes the sample size needed too large for some sample combustion systems. Also, the metallic character of the samples complicates sample combustion or oxidation. The Erlangen accelerator mass spectrometry group uses an elemental analyzer for the sample combustion, directly followed by a reduction facility. As the carbon content and sample size for iron samples are unsuitable for combustion in an elemental analyzer, 2 alternative approaches are to (a) avoid oxidation and reduction, or (b) extract the carbon from the iron, prior to combustion. Therefore, 2 different pathways were explored. One is direct sputtering of the unprocessed iron sample in the ion source. The other is the complete chemical extraction of carbon from the iron sample and dating of the carbonaceous residue. Also, different methods for cleaning samples and removing contamination were tested. In Erlangen, a Soxhlet extraction is employed for this purpose. Also, the sampling of the iron sample by drilling or cutting can be a source of contamination. Thus, the measurement of iron drill shavings yielded ages that were far too high. The first results for iron samples of known age from 2 archaeological sites in Germany are presented and discussed.