• Radiocarbon AMS Data Analysis: From Measured Isotopic Ratios to 14C Concentrations

      Zoppi, Ugo (Department of Geosciences, The University of Arizona, 2010-01-01)
      Radiocarbon accelerator mass spectrometry (AMS) measurements are always carried out relative to internationally accepted standards with known 14C activities. The determination of accurate 14C concentrations relies on the fact that standards and unknown samples must be measured under the same conditions. When this is not the case, data reduction is either performed by splitting the collected data set into subsets with consistent measurement conditions or by applying correction factors. This paper introduces a mathematical framework that exploits the intrinsic variability of an AMS system by combining arbitrary measurement parameters into a normalization function. This novel approach allows the en-masse reduction of large data sets by providing individual normalization factors for each data point. Both general features and practicalities necessary for its efficient application are discussed.
    • Radiocarbon and Archaeology in Japan and Korea: What Has Changed because of the Yayoi Dating Controversy?

      Shoda, S. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Since the sensational 2003 announcement that pushed the start of the Yayoi period back by 500 yr, archaeologists working on 1st millennium BC material from northeast Asia have had to switch from the older short chronology to a new long chronology. However, this change need not apply to the entire northeast Asian region as China's chronology is tied to written records. The timeline of the Korean peninsula, intermediate between the Chinese and Japanese ones, needs to be reexamined. The chronology of the 1st millennium BC in the Korean peninsula is still in dispute, in part because many of the radiocarbon dates lack clear archaeological contexts. This paper shows that a reliable typological relationship observed in archaeological materials existed at this time linking northeast Asia from China to Japan. This paper includes absolute dates based on the initial AMS 14C measurements of charred crops from South Korean sites.
    • Radiocarbon and Stable Carbon Isotope Analyses of Land Snails from the Chinese Loess Plateau: Environmental and Chronological Implications

      Xu, Bing; Gu, Zhaoyan; Han, Jingtai; Liu, Zongxiu; Pei, Yunpeng; Lu, Yanwu; Wu, Naiqin; Chen, Yongfu (Department of Geosciences, The University of Arizona, 2010-01-01)
      Paired radiocarbon and stable carbon analyses have been carried out on aragonite shells and organic soft bodies of snails from the Chinese Loess Plateau in order to explore the possibility of using these kinds of samples as environmental and chronological indicators. Results show that the soft bodies exhibit 14C concentrations similar to those of plant leaves, indicating that carbon in the soft bodies is fixed from organic diets. The aragonite shells are depleted in 14C compared to the soft bodies due to ingestion of 14C-depleted carbonate. This depletion shows a consistent pattern across the Chinese Loess Plateau, implying a good potential for the snail shells to be applicable for 14C dating with a simple correction. The 13C values measured for aragonite shells display a linear relationship with those obtained for the soft bodies with a constant offset. In addition, the carbon derived from organic diets accounts for more than 70% of the total shell carbon. This fact suggests that stable carbon isotope composition of aragonite shells mainly reflects that of organic diet, and could be used as a reliable indicator of paleodiet in the Chinese Loess Plateau.
    • Radiocarbon and Stable Carbon Isotope Ratio Data from a 4.7-m-long Sediment Core of Lake Baikal (Southern Siberia, Russia)

      Nara, Fumiko Watanabe; Watanabe, Takahiro; Nakamura, Toshio; Kakegawa, Takeshi; Katamura, Fumitaka; Shichi, Koji; Takahara, Hikaru; Imai, Akio; Kawai, Takayoshi (Department of Geosciences, The University of Arizona, 2010-01-01)
      A sediment core (VER99G12; core length, 4.66 m) was taken from the Buguldeika Saddle of Lake Baikal in 1999. Radiocarbon measurements of total organic carbon (TOC) and pollen concentrate fractions from the VER99G12 core were performed by a Tandetron accelerator mass spectrometry (AMS) system (Model-4130, HVEE) at Nagoya University. The AMS 14C ages showed that the VER99G12 core spans the past ~30 cal ka BP (from the MIS 3 to present), and the average sedimentation rate of this core was calculated to be 13.6 cm/kyr based on the calibrated ages. This means that the time resolution of VER99G12 sediment samples in this study is better than ~70-80 yr/cm. Stable carbon isotope ratios of TOC (13CTOC) in the VER99G12 core varied widely from about 26.6 to 31.3 during the last glacial/post-glacial transition period (about 17-12 cal ka BP). Therefore, a rapid change in the carbon sources in Lake Baikal occurred in the last glacial/post-glacial transition period is concluded.
    • Radiocarbon and Tritium Levels along the Romanian Lower Danube River

      Varlam, Carmen; Stefanescu, Ioan; Cuna, Stela; Vagner, Irina; Faurescu, Ionut; Faurescu, Denisa (Department of Geosciences, The University of Arizona, 2010-01-01)
      The Lower Danube Basin covers the Romanian-Bulgarian sub-basin downstream from Cazane Gorge and the sub-basins of the Siret and Prut rivers. To extensively survey the Romanian nuclear power plant impact on the Danube water, tritium and radiocarbon baseline values are required. Therefore, the reported study tried to establish these values based on a 2-yr sampling campaign covering 975 km of the Danube from Cazane Gorge to Tulcea. The tributaries Cerna, Jiu, Olt, and Arges were also included in this study. During the sampling campaigns, tritium concentration of different sampling locations showed values between 7 ± 2.1 and 33.5 ± 2.3 TU. Measured 14C activity for the same locations ranged between 88.45 ± 1.46 and 112.36 ± 1.56 pMC. Lower values were recorded for tributaries: between 8.3 ± 2.1 and 12.2 ± 2.2 TU for tritium and between 67.3 ± 1.29 and 86.04 ± 1.42 pMC for 14C. Despite the nuclear activity in the observed areas, tritium and 14C activities presented slightly higher values for specific locations without any influence on Danube River water.
    • Radiocarbon Chronology for Early Caves of the Mogao Grottoes at Dunhuang, China

      Qinglin, G.; Takabayashi, H.; Nakamura, T.; Gangquan, C.; Okada, K.; Bomin, S.; Yuquan, F.; Nishimoto, H. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The Mogao Grottoes site at Dunhuang is one of the largest stone cave temples in China. The site features 735 caves with Buddhist mural paintings. To investigate the chronology of early caves of the Mogao Grottoes, radiocarbon dates were measured by accelerator mass spectrometry (AMS) on plant remains collected from 4 caves: 268, 272, 275, and 285. Caves 268, 272, and 275 are regarded (by archaeological analysis) to be the earliest existing caves in the Mogao Grottoes. The fourth cave, 285, features inscriptions on the north wall mentioning the oldest dates of the Chinese Mogao era. Plant materials, taken from the plaster layer of mural paintings and core materials from statues, were collected as samples (n = 11) for AMS 14C dating at Nagoya University. Two samples from cave 275 gave calibrated 14C ages of cal AD 380-430 (1 sigma). The other samples resulted in a time interval of cal AD 400-550. The calibrated 14C ages obtained for the samples taken from painted murals and the statues in cave 285 are consistent with the date given by the inscription remaining on the cave's north wall.
    • Radiocarbon Chronology with Marine Reservoir Correction for the Ritidian Archaeological Site, Northern Guam

      Carson, Mike T. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Archaeological investigations at the Ritidian Site in Guam provide a series of radiocarbon dates spanning the potential range of human presence in the region. Paired marine and terrestrial samples offer a basis for R calculation, as well as evaluation of the utility of different types of marine samples for 14C dating of archaeological contexts. The results indicate an early period of temporary fishing camp activity in the context of higher sea level and little or no stable beach, followed by larger-scale residential activity in the context of lower sea level and an extensive stable beach landform.
    • Radiocarbon Dates Documenting the Neolithic-Bronze Age Transition in Korea

      Kim, J. C.; Bae, C. J. (Department of Geosciences, The University of Arizona, 2010-01-01)
      We report radiocarbon dates for ~150 archaeological sites in Korea belonging to the Neolithic-Bronze Age transition period. From the present compilation, we find that the Neolithic-Bronze Age transition in Korea started as early as ~2300 BC and continued over the course of 800-900 yr with peaks representing population increases occurring 2-3 times. Compared with cases in other regions of the world, the Neolithic-Bronze Age transition in Korea was similar in both magnitude and transition time. However, the process in Korea appears to have occurred about 2000 yr later. Further, we find that the attempt to explain the Neolithic-Bronze Age transition in Korea as a migration hypothesis based only on a sudden population increase is not tenable.
    • Radiocarbon Dating of Individual Amino Acids from Archaeological Bone Collagen

      McCullagh, J. S. O.; Marom, A.; Hedges, R. E. M. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Since the development of accelerator mass spectrometry (AMS) for radiocarbon dating in the late 1970s, its ability to date small samples of bone has been of huge importance in archaeology and Quaternary paleoecology. The conventional approach to sample preparation has been to extract and gelatinize protein, which is then combusted and graphitized for analysis. However, this 'bulk protein' can contain a heterogeneous mixture of non-collagenous molecules, including humic acids and other soil components that may be of a different age than the bone and therefore affect the accuracy of its 14C date. Sample pretreatment methods have been an important area of development in recent years but still show inadequacies for the dating of severely contaminated bone. The idea of isolating and dating individual compounds such as single amino acids, to improve dating accuracy, has been discussed in the literature since the 1960s. Hydroxyproline, for example, makes up over 10% of bone collagen but is extremely rare in most other animal proteins, increasing the chances of its presence being endogenous to the individual being dated. Its successful isolation has therefore been considered a potential 'gold standard' for dating archaeological bone; however, extracting and suitably purifying single amino acids from bone has proved a challenging task. This paper presents a novel method for the compound-specific 14C dating of individual amino acids, including hydroxyproline, from archaeological bone protein. It is based on a preparative, mixed-mode liquid chromatography separation of underivatized amino acids, entirely in aqueous solution and free of organic solvents. The method is presented here in detail including application to standard bone samples establishing its accuracy and background carbon contribution. Results from 14C dating hydroxyproline and other individual amino acids, from both historical and archaeological bone, are shown to provide AMS dates that are statistically indistinguishable from those of the bulk protein.
    • Radiocarbon Dating of Kohitsugire Calligraphies Attributed to Asukai Masatsune and the Periods of Origin of Genji Monogatari Emaki and Ban-dainagon Ekotoba

      Oda, H.; Ikeda, K. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Genji monogatari emaki and Ban-dainagon ekotoba are Japanese national treasures. Although the periods in which they were painted have not been accurately determined, radiocarbon dating cannot be applied to these priceless artifacts because of the destructive nature of 14C dating. In this study, the periods of their origin were determined by 14C dating the kohitsugire calligraphy. Kohitsugire are ancient paper sheets containing graceful calligraphy. They originally were part of ancient manuscripts. Two kohitsugire named Imaki-gire and Kingin-kirihaku-wakanroeishu-gire are written in the same style as Genji monogatari emaki and Ban-dainagon ekotoba. Although Imaki-gire and Kingin-kirihaku-wakanroeishu-gire had been attributed to Asukai Masatsune (AD 1170-1221) on the basis of the kiwamefuda certificates, recent calligraphical and paleographical studies suggest that they are genuine handwritings of Fujiwara no Norinaga (AD 1109-1180). We applied 14C dating by accelerator mass spectrometry (AMS) to Imaki-gire and Kingin-kirihaku-wakanroeishu-gire. The calibrated 14C ages of both the kohitsugire indicated timing close to the peak of Fujiwara no Norinaga's career as a calligraphist. Based on the associations between the dated texts and the 14C results, it is concluded that the Genji monogatari emaki and Ban-dainagon ekotoba paintings could have been created in the middle of 12th century.
    • Radiocarbon Dating of the Amphipolis Bridge in Northern Greece, Maintained and Functioned for 2500 Years

      Maniatis, Y.; Malamidou, D.; Koukouli-Chryssanthaki, H.; Facorellis, Y. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The remains of a wooden construction, recovered in the 1970s at the northwest sector of the walls of the ancient city of Amphipolis (northern Greece), have been recognized as foundation remains of a wooden bridge described by Thucydides in his description of the events that took place at Amphipolis in 424-422 BC, during the Peloponnesian War. Frequent repairs in the Roman, Byzantine, and even Ottoman periods are very probable. In the last 10 yr, conservation has been done to enhance this unique monument. This work involves systematic investigation with radiocarbon dating of all the verified or suspected phases of this wooden bridge. The dating results reveal the beginning of construction most probably in the Archaic period and confirm beyond a doubt that the major construction phase took place in Classical times. Successive phases, related to repairs rather than to major reconstructions, have been detected during the Hellenistic, Roman, Early Christian, and Byzantine periods as well as the Ottoman era. The combined archaeometric and archaeological evidence leads to the remarkable conclusion that this bridge was functioning for about 2500 yr.
    • Radiocarbon Dating of the Last Volcanic Eruptions of Ciomadul Volcano, Southeast Carpathians, Eastern-Central Europe

      Harangi, Sz; Molnár, M.; Vinkler, A. P.; Kiss, B.; Jull, A. J. T.; Leonard, A. G. (Department of Geosciences, The University of Arizona, 2010-01-01)
      This paper provides new accelerator mass spectrometry (AMS) radiocarbon age data for the last volcanic events in the Carpathian-Pannonian region of eastern-central Europe. The eruption ages were determined on charcoal fragments collected from pumiceous pyroclastic flow deposits at 2 localities of the Ciomadul Volcano. Two charcoal samples from the southeastern margin of the volcano (Bixad locality) set the date of the last volcanic eruption to 27,200 +/- 260 yr BP (29,500 +/- 260 cal BC). On the other hand, our data show that the Tusnad pyroclastic flow deposit, previously considered as representing the youngest volcanic rock of the region, erupted at ~39,000 yr BP (~41,300 cal BC). Thus, a period of dormancy more than 10,000 yr long might have elapsed between the 2 volcanic events. The different ages of the Tusnad and Bixad pyroclastic flow deposits are confirmed also by the geochemical data. The bulk pumices, groundmass glass, and the composition of the main mineral phases (plagioclase and amphibole) suggest eruption of slightly different magmas. Considering also the assumed long volcanic history (~600 ka) of the Ciomadul, these data suggest that further detailed studies are necessary on this seemingly inactive volcano in order to evaluate the possible renewal of volcanic activity in the future.
    • Radiocarbon Dating of the Mansuri Paleolithic Site, Cheongwon, Korea

      Kim, K. J.; Jull, A. J. T.; Kim, Ju Yong; Lee, Yung Jo; Hong, Wan; Park, Jung Hun; Woo, Hyung Joo (Department of Geosciences, The University of Arizona, 2010-01-01)
      Construction of a new science complex in Osong, Cheongwon-gun, Korea, has allowed the investigation of 14 different Paleolithic localities, excavated during 2005-2007. Here, we investigated localities 1 and 12 of the Mansuri Paleolithic site to obtain chronological information using radiocarbon dating. The soil deposition rates varied from 0.09 to 0.15 mm/yr over the period ranging from 33 to 31 kyr BP for locality 1. Locality 12 samples were more recent, 10 ka, and have similar accumulation rates, averaging 0.11 mm/yr. The soil ages of locality 12 were found to be younger than 10 kyr BP. Results for both soil and organic materials at this locality gave much younger ages at shallower depths than the ages expected by the Korean Paleolithic cultural history for this region. Therefore, these more recent deposits may not be associated with the cultural layers and are interpreted to have been hydrologically modified following emplacement. 14C dates of the soil and organic materials at locality 12 confirm that there is evidence for multiple human occupations throughout the last 9 kyr BP.
    • Radiocarbon Dating, Stable Isotope Analysis, and Diet-Derived Offsets in 14C Ages from the Klin-Yar Site, Russian North Caucasus

      Higham, T.; Warren, R.; Belinskij, A.; Härke, H.; Ood, R. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The influence of geothermally derived carbon on the radiocarbon dating of human bone from archaeological sites is poorly understood and has rarely been rigorously examined. This study identifies a previously unknown reservoir effect at the archaeological site of Klin-Yar in the Russian North Caucasus. AMS-dated human bones yielded results that were older than expected when compared with dates of coins found in the same grave contexts. We investigated the reasons for this offset by AMS dating modern plant, fish, and water samples to examine the source of the old carbon. We identified a potential source in geothermally derived riverine and spring water, with an apparent age of several thousand years, and hypothesize that carbon from here is being transferred through the food chain to humans. If humans consume resources from the local rivers, such as fish, then they ought to be affected by this reservoir offset. An extensive analysis of carbon and nitrogen isotopes of human and animal bone showed evidence for a mixed diet that may be masking the amount of freshwater-derived protein being consumed. Due to the highly variable nature of the 14C offset (0 to ~350 yr), no suitable average correction factor is applicable to correct for the human dates at the site. A 14C chronology based on dates obtained from terrestrial ungulate bones, which we subsequently obtained, is instead a more reliable indicator of age.
    • Radiocarbon in the Air of Central Europe: Long-Term Investigations

      Svetlik, I.; Povinec, P. P.; Molnár, M.; Vána, M.; Šivo, A.; Bujtás, T (Department of Geosciences, The University of Arizona, 2010-01-01)
      Regional levels of radiocarbon have been monitored in order to investigate the impact of fossil fuel combustion on the activity of atmospheric 14CO2 in central Europe. Data from atmospheric 14CO2 monitoring stations in the Czech Republic, Slovakia, and Hungary for the period 2000-2008 are presented and discussed. The Prague and Bratislava monitoring stations showed a distinct local Suess effect when compared to the Jungfraujoch clean-air monitoring station. However, during the summer period, statistically insignificant differences were observed between the low-altitude stations and the high-mountain Jungfraujoch station. 14C data from the Hungarian monitoring locality at Dunafldvr and the Czech monitoring station at Kosetice, which are not strongly affected by local fossil CO2 sources, indicate similar grouping and amplitudes, typical for a regional Suess effect.
    • Radiocarbon Laboratories

      Department of Geosciences, The University of Arizona, 2010-01-01
    • Radiocarbon Results from the Iron IIa Site of Atar Haroa in the Negev Highlands and Their Archaeological and Historical Implications

      Boaretto, E.; Finkelstein, I.; Shahack-Gross, R. (Department of Geosciences, The University of Arizona, 2010-01-01)
      In this article, we present a set of radiocarbon measurements from Atar Haroa, a site that belongs to the early Iron IIA Negev Highlands settlement system in southern Israel. The results place activity at the site in the 9th century BCE, with a possibility that it was founded in the 10th century BCE, probably in the second half. The Atar Haroa measurements seem to indicate that the early Iron IIA phase in the ceramic typology of Israel lasted until the mid-9th century BCE--somewhat later than previously suggested. These new data shed light on several issues related to the history of southern Israel in the late 10th and 9th centuries BCE.
    • Radionuclides in Ancient Relics Obtained from the Matsusaki Site and the Hirohata Shellmound on the Pacific Coast of Japan

      Ohta, T.; Mahara, Y.; Kubota, T.; Saito, Y.; Fukutani, S.; Fujii, T.; Ando, A.; Nakata, E.; Nakano, T.; Abe, Y.; et al. (Department of Geosciences, The University of Arizona, 2010-01-01)
      We compared 2 archaeological relics of different preservation environments, white substances adhering to a vessel from the Matsusaki site and to earthenware from Hirohata, by measuring their environmental radioactivity, 14C, 228Ra/226Ra, 234U/238U, and 87Sr/86Sr, and major element contents (Ca, Sr, Mg, Fe, and Mn). The results showed that the 2 materials were somewhat different and also reflected differences in their preservation environments. The chemical elements that were more abundant in the Matsusaki sample than in the Hirohata sample, Fe, Mn, 238U, and 232Th (parent of 228Ra), are also abundant in seaweed or seagrass. Contamination by 14C derived from rainwater after atmospheric nuclear tests was clearly observed in the white substance from Hirohata.
    • Reconstruction of 130-kyr Relative Geomagnetic Intensities from 10Be in Two Chinese Loess Sections

      Zhou, Weijian; Xian, Feng; Beck, Warren; Jull, A. J. Timothy; An, Zhisheng; Wu, Zhenkun; Liu, Min; Chen, Maobai; Priller, Alfred; Kutschera, Walter; et al. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Efforts to extract weak geomagnetic excursion signals from Chinese loess-paleosol 10Be have generally been unsuccessful due to the complexities of its accumulation, because the geomagnetic and climate (precipitation and dust) signals contained in loess-paleosol sequence are tightly overprinted. Here, we present a reconstruction of geomagnetic relative paleointensities for the past 130 kyr from 10Be records in 2 Chinese loess-paleosol sections using a correction based on the correlation of 10Be with magnetic susceptibility (SUS) to remove the climatic contamination. Both these records reveal the Laschamp and Blake events, which lie in the loess and paleosol (L1SS1 and S1SS3) horizons corresponding to mid-MIS 3 and 5e, respectively. The good agreement between our results and other geomagnetic intensities reconstructions from Atlantic and Pacific sediments indicates that our method is robust. Our study suggests the potential application of loess-paleosol 10Be for reconstructing geomagnetic intensity variations spanning the whole Quaternary.
    • Refining Background Corrections for Radiocarbon Dating of Bone Collagen at ORAU

      Wood, R. E.; Bronk Ramsey, C.; Higham, T. F. G. (Department of Geosciences, The University of Arizona, 2010-01-01)
      During the laboratory pretreatment of samples for radiocarbon dating, small amounts of carbon may be added to a sample. Contamination can be incorporated at any stage: during chemical pretreatment, combustion to CO2, graphitization, or accelerator mass spectrometry (AMS) measurement. Such carbon contamination is often modern in age, and so can have an especially severe effect on samples older than ~25 ka BP. During the extraction of collagen from bone using the ultrafiltration protocol at the Oxford Radiocarbon Accelerator Unit (ORAU), small amounts of young carbon are added to the sample. Currently, this contamination is poorly characterized when less than 10 mg of collagen is extracted from a bone. Demand to date small collagen samples with 14C concentrations that approach the detection limit of AMS measurement has increased recently with the growing interest in, for example, directly dating Neanderthal remains and Upper Paleolithic bone artifacts. This paper aims to reduce the minimum collagen sample size required to produce a reliable date from 10 to 5 mg by re-examining the combustion background and subsequently the pretreatment background for bone. The average of 136 measurements of directly combusted nylon suggests that 0.0007 0.001 mg of modern carbon is added to each sample, although the distribution is positively skewed. Regression analysis of the measurements of 52 collagen samples extracted from a bone of background age results in a background of just less than 50,000 BP for bone treated at ORAU.