• Obituary: Austin Long

      Eastoe, C.; Leavitt, S.; Tanner Elliott, K.; Sewell, D. (Department of Geosciences, The University of Arizona, 2010-01-01)
    • On-Line Radiocarbon Measurements of Small Samples Using Elemental Analyzer and MICADAS Gas Ion Source

      Ruff, M.; Fahrni, S.; Gaggeler, H. W.; Hajdas, I.; Suter, M.; Synal, H-A; Szidat, S.; Wacker, L. (Department of Geosciences, The University of Arizona, 2010-01-01)
      An on-line measurement system was installed at the MICADAS in Zurich, using an elemental analyzer (EA) as a combustion unit to enable direct radiocarbon measurement of samples containing carbon in the range of 5-100 g possible with minimum effort. The samples are combusted in small capsules and the gaseous combustion products are separated by the EA. The carbon dioxide leaving the EA in a high helium flow is concentrated on a small external trap containing X13 zeolite adsorber material. This new concept, avoiding a cryogenic trapping for the enrichment step, allows the construction of a very compact system able to work even with the smallest samples. Concentrated on the external trap, the carbon dioxide is flushed into the gas-tight syringe of our gas inlet system using a low helium stream. The gas mixture is measured with the MICADAS gas ion source. Several different sample capsules were analyzed to minimize the major blank contribution coming from the sample vessel. The best results were achieved with 25-L tin capsules, which contained only 0.34 0.13 g carbon at 65 pMC. This work describes the development of the on-line system and the protocol for measurement runs. Results are presented for on-line measurements of reference materials and a comparison is performed with typical dating samples measured previously as graphite targets. Finally, relevance and limitations of on-line measurements are discussed.
    • Optimization of 236U AMS at CIRCE

      De Cesare, Y.; Quinto, F.; Sabbarese, C.; D, N.; D'Onofrio, A.; Alanella, L.; Petraglia, A.; Roca, V.; Terrasi, F. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Actinide isotopes are present in environmental samples at ultra-trace levels (236U concentration is quoted to be on the order of pg/kg or fg/kg). Their detection requires the resolution of mass spectrometry (MS) techniques, but only accelerator mass spectrometry (AMS) has the sensitivity required. In order to perform the isotopic ratio measurements of actinides, such as 236U/238U, an upgrade of the Center for Isotopic Research on Cultural and Environmental Heritage accelerator (CIRCE) in Caserta, Italy, has been performed. The system was originally equipped for radiocarbon AMS measurements. The main difficulty of AMS measurement of 236U is the intense neighboring beam of 238U. Although most of the 238U ions are suppressed by means of magnetic and electrostatic elements, a small fraction of this intense beam can interfere with the rare isotopes. This paper reports the preliminary results of the 236U/238U isotopic ratio measurement limit 5.6 x 10^(-11)), aimed also to better understand the origin of background ions. For this purpose, a large 16-strip silicon detector providing spatial resolution has been used. In addition, calculations to assess the performance of the system obtained by adding a high-resolution time of flight-energy (TOF-E) detector are discussed.
    • Optimization of the Graphitization Process at AGE-1

      Němec, Mojmir; Wacker, Lukas; Gäggeler, Heinz (Department of Geosciences, The University of Arizona, 2010-01-01)
      The reaction conditions for the graphitization of CO2 with hydrogen were optimized for a fast production of high-quality carbon samples for accelerator mass spectrometry (AMS) measurement. The iron catalyst in use is first oxidized by heating with air to remove possible carbon and other impurities and then after evacuation reduced back to iron with hydrogen in several flushing steps to remove any iron oxide. The optimum conditions for a fast graphitization reaction were experimentally determined by changing the reaction temperatures and the H2/CO2 ratio. The resulting graphite samples were measured by AMS to find the smallest isotopic changes (13C) at a minimum of molecular fragment formation (13CH current). The improvements are based on thermodynamic data and are explained with Baur-Glaessner diagrams.
    • Paleodiet Reconstruction of Human Remains from the Archaeological Site of Natfieh, Northern Jordan

      Al-Bashaireh, K.; Al-Shorman, A.; Rose, J.; Jull, A. J. T.; Hodgins, G. (Department of Geosciences, The University of Arizona, 2010-01-01)
      This investigation concerns human teeth and bones from the site of Natfieh, north Jordan. Nitrogen and carbon isotope analyses were used to model the paleo-economy by reconstructing Natfieh's paleodiet during a specific time period. 14C dating of human teeth and bones from the site of Natfieh, north Jordan, demonstrate that they belong to the Early Roman period and match the archaeological date from the tomb and grave goods typology. Stable isotope analyses of these humans have provided new information about the subsistence and society of individuals buried at Natfieh. Natfieh is today agriculturally productive and must have been so in antiquity with most of the foodstuffs having been produced locally. The long distance between Natfieh and the closest aquatic food source (Mediterranean Sea and Lake Tiberias) and the high cost of land transportation might be the reason for the low consumption of marine protein. The results agree with past research on the Roman diet showing that plants were the common source of food for the Romans and fish may have been restricted to elite members of the society.
    • Paleoearthquakes as Anchor Points in Bayesian Radiocarbon Deposition Models: A Case Study from the Dead Sea

      Kagan, Elisa J.; Stein, Mordechai; Agnon, Amotz; Ramsey, Christopher Bronk (Department of Geosciences, The University of Arizona, 2010-01-01)
      The Bayesian statistical method of the OxCal v 4.1 program is used to construct an age-depth model for a set of accelerator mass spectrometry (AMS) radiocarbon ages of organic debris collected from a late Holocene Dead Sea stratigraphic section (the Ein Feshkha Nature Reserve). The model is tested for a case where no prior earthquake information is applied and for a case where there is incorporation of known ages of 4 prominent historical earthquakes as chronological anchor points along the section. While the anchor-based model provided a tightly constrained age-depth regression, the "non-anchored" model still produces a correlation where most of the 68% or 95% age ranges of the 52 seismites can be correlated to historical earthquakes. This presents us with the opportunity for high-resolution paleoseismic analysis and comparison between various sites.
    • Paleoenvironment of Medieval Archaeological Sites in Central Japan: Assemblage Analysis and 14C Dating of Insect Fossils

      Okuno, E.; Mori, Y.; Nakamura, T. (Department of Geosciences, The University of Arizona, 2010-01-01)
      This study aimed to investigate the paleoenvironment of 2 Medieval archaeological sites, Onigashioya and Ooke, in central Japan, by assemblage analyses of insect fossils preserved in sediments at the sites. In the Onigashioya site located in Mie Prefecture, the sclerites of insect fossils classified as the "village" type were detected, which indicates that human activities, and in particular farming, were taking place there. Rice paddies and fields existed near the site, which explains why many insects harmful to rice plants and crops were detected in the area. The radiocarbon date for sclerite remains of Hydrophilus acuminatus, an aquatic beetle that live in rice paddy fields, was calibrated to be cal AD 1010-1155. Analysis of sclerite remains of Craspedonotus tibialis, a ground beetle that typically inhabits seashore environments, resulted in a date of cal AD 1020-1155. This finding suggests that human settlements existed in the seaside areas of the Onigashioya site in the 11th century AD. In the Ooke site located in Aichi Prefecture, "insect pits" were found, which are structural remains containing a large number of Anomala rufocuprea, an insect that preys on field crops. Farmers would have gathered the insects from the fields and buried the dead remains in the pits. Accelerator mass spectrometry (AMS) 14C dates on sclerite remains of A. rufocuprea ranged from cal AD 1264 to 1385. It should be noted that fruit trees and vegetable crops were planted widely around the site in the 13th century AD. As the result, A. rufocuprea propagated greatly around the site in that period. It is probable that many insects harmful to field crops multiplied largely in this region due to the development of local woods and plains into farming fields. This type of development occurred throughout Japan during the Medieval period.
    • Personal Recollections of a Good Experiment

      Nelson, E. (Department of Geosciences, The University of Arizona, 2010-01-01)
    • Pre-Bomb Marine Reservoir Ages in the Western Pacific

      Yoshida, Kunio; Hara, Tatsuaki; Kunikita, Dai; Miyazaki, Yumiko; Sasaki, Takenori; Yoneda, Minoru; Matsuzaki, Hiroyuki (Department of Geosciences, The University of Arizona, 2010-01-01)
      In this study, molluscan shells housed at the University Museum, the University of Tokyo, provided a new set of region-specific correction values (R) for the western Pacific, in particular for the central part of the main islands in the Japanese Archipelago and the southwest islands of Japan. The values of 40 total samples were calculated from 11 regions. North of the main islands and in the Ryukyu Islands, the mean R values showed comparatively small values, 5-40 14C yr; in the central part of the main islands, these values were 60-90 14C yr.
    • Pre-Bomb Marine Reservoir Variability in the Kimberley Region, Western Australia

      O'Connor, Sue; Ulm, Sean; Fallon, Stewart J.; Barham, Anthony; Loch, Ian (Department of Geosciences, The University of Arizona, 2010-01-01)
      New Delta-R values are presented for 10 known-age shells from the Kimberley region of northwest Australia. Previous estimates of Delta-R for the Kimberley region are based on only 6 individual shell specimens with dates of live collection known only to within 50 yr (Bowman 1985a). Here, we describe the results of our recent attempts to constrain Delta-R variability for this region by dating a suite of known-age pre-AD 1950 shell samples from the Australian Museum and Museum Victoria. A regional Delta-R of 58 +/- 17 14C yr for open waters between Broome and Cape Leveque is recommended based on 7 of these specimens. The criteria used to select shells for dating and inclusion in the regional mean are discussed.
    • Precise Comparison of 14C Ages from Choukai Jindai Cedar with IntCal04 Raw Data

      Suzuki, Kayo; Sakurai, Hirohisa; Takahashi, Yui; Sato, Taiichi; Gunji, Shuichi; Tokanai, Fuyuki; Matsuzaki, Hiroyuki; Tsuchiya, Yoko (Department of Geosciences, The University of Arizona, 2010-01-01)
      We measured the radiocarbon ages of 165 single-year tree rings from a Japanese Choukai Jindai cedar using accelerator mass spectrometry (AMS). By wiggle-matching the Choukai_AMS data set to the IntCal04 calibration data using OxCal v 3.10 and using the variation of the correlation coefficients between the Choukai_AMS and IntCal04 data sets, we precisely re-estimated that the 321 Choukai Jindai cedar tree rings range from 780 to 460 cal BC with an accuracy of 8 yr. The Choukai_AMS data set is older than the 3 raw data sets of European tree rings that comprise IntCal04. The Belfast and Seattle data sets are younger by -21.3 +/- 5.5 and -22.7 +/- 5.6 14C yr, respectively. The Choukai Jindai cedar is ~22 14C yr older than the European tree rings, which is equivalent to an offset of -2.8‰ in 14C. In addition, the Choukai_AMS data set correlates well with the Belfast and Seattle data sets, with correlation coefficients of 0.89 and 0.68, respectively, between the temporal profiles. Hence, the temporal profile of the Choukai 14C ages shows a global variation.
    • 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.