• Calibrated 14C Ages of Jomon Sites, NE Japan, and Their Significance

      Omoto, K.; Takeishi, K.; Nishida, S.; Fukui, J. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The traditional archaeological chronology in the Japanese Islands during the Jomon period was essentially based on the relative age given to cord-impressed patterns marked on pottery, as well as the shape of the pottery and the thickness of the cultural layers that were excavated. We aimed to correlate the classical archaeological chronology with calibrated radiocarbon dates, to posit a new chronology for the Jomon period in northeastern Japan. We calibrated 80 accelerator mass spectrometry (AMS) 14C dates from NE Japan and reconstructed a chronological timetable for Hokkaido and the Tohoku District. We collected 43 samples from 5 shellmounds and 2 archaeological sites on Hokkaido Island and 4 shellmounds in the Tohoku District in order to determine the calibrated age of their sites. R values used on Hokkaido Island and the Tohoku District were between 282 and -158 yr and between 0 and -40 yr, respectively. The large R value for the eastern part of Hokkaido Island indicates the influence of the Oyashio Current, while an anomalous R value was obtained from northern Hokkaido Island. These figures show larger apparent R values than those from southwest Japan (Nakamura et al. 2007). The calibrated Jomon period in the investigated area was from 2000 to 200 yr younger than the previous chronology. Calibrated 14C ages of the shellmounds investigated ranged between ~6000 and 3000 yr, correlating to the Early Jomon and Final Jomon periods as indicated by the former archaeological chronology of Honshu Island.
    • Calibration of Mangerud's Boundaries

      Walanus, Adam; Nalepka, Dorota (Department of Geosciences, The University of Arizona, 2010-01-01)
      The "calibration" of arbitrarily defined (in some sense, "conventional") ages, given in conventional radiocarbon years BP, is now becoming necessary because the term "radiocarbon age" is used less often in archaeological and Quaternary practice. The standard calibration procedure is inappropriate here because Mangerud's boundaries are not measurement results. Thus, another approach to the problem is proposed in order to model the natural situation of many, uniformly distributed, dated samples, which should be similarly divided by the original and "calibrated" boundary. However, the result depends on the value of the typical measurement error and is not unequivocal.
    • Carbon Isotope Measurements of Surface Seawater from a Time-Series Site off Southern California

      Hinger, Elise N.; Santos, Guaciara M.; Druffel, Ellen R. M.; Griffin, Sheila (Department of Geosciences, The University of Arizona, 2010-01-01)
      We report carbon isotope abundances of dissolved inorganic carbon (DIC) in surface seawater collected from a time-series site off the Newport Beach Pier in Orange County, California. These data represent the first time series of ∆14C data for a coastal southern California site. From a suite of samples collected daily from 16 October to 11 November 2004, ∆14C values averaged 32.1 +/- 4.4. Freshwater input from the Santa Ana River to our site caused ∆14C and 13C values to decrease. Since this initial set of measurements, a time-series site has been maintained from November 2004 to the present. Surface seawater has been collected bimonthly and analyzed for ∆14C, delta-13C, salinity, and sigma-CO2 concentrations. Water samples from the Santa Ana River were collected during the wet season. California sea mussels and barnacle shells, ranging from 4 to 6 months old, were also collected and analyzed. Results from May 2005 to January 2008 show no long-term changes in delta-13C DIC values. ∆14C DIC values over the 2005-2006 period averaged 33.7; high ∆14C values were observed sporadically (every 6-7 months), suggesting the presence of open water eddies at our site. Finally, in 2007, a stronger upwelling signal was apparent as indicated by correlations between ∆14C, salinity, and the Bakun index, suggesting that the ∆14C record is an indicator of upwelling in the Southern California Bight.
    • Centre of Research and Restoration of the Museums of France: AMS Radiocarbon Dates List 1

      Richardin, P.; Gandolfo, N.; Moignard, B.; Lavier, C.; Moreau, C.; Cottereau, E. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The national project for the measurement of radiocarbon includes different scientific partners for the accelerator named ARTEMIS (French acronym for Accélérateur pour la Recherche en sciences de la Terre, Environnement, Musologie Install Saclay), available to the scientific community since 2004 (Cottereau et al. 2007). The French Ministry of Culture uses this accelerator mass spectrometry (AMS) facility at the request of archaeologists or curators of museums or of historical monuments. For the preparation of some samples, a laboratory has been installed at the Centre of Research and Restoration of the Museums of France, located in the Louvre Palace. In this report, the first data carried out on vegetal samples from museum objects or archaeological remains, dates are presented in terms of yr BP (before AD 1950).
    • Centuries of Marine Radiocarbon Reservoir Age Variation within Archaeological Mesodesma donacium Shells from Southern Peru

      Jones, Kevin B.; Hodgins, Gregory W. L.; Etayo-Cadavid, Miguel F.; Andrus, C. Fred T.; Sandweiss, Daniel H. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Mollusk shells provide brief (5 yr per shell) records of past marine conditions, including marine radiocarbon reservoir age (R) and upwelling. We report 21 14C ages and R calculations on small (~2 mg) samples from 2 Mesodesma donacium (surf clam) shells. These shells were excavated from a semi-subterranean house floor stratum 14C dated to 7625 +/- 35 BP at site QJ-280, Quebrada Jaguay, southern Peru. The ranges in marine 14C ages (and thus R) from the 2 shells are 530 and 170 14C yr; R from individual aragonite samples spans 130 +/- 60 to 730 +/- 170 14C yr. This intrashell 14C variability suggests that 14C dating of small (time-slice much less than 1 yr) marine samples from a variable-R (i.e. variable-upwelling) environment may introduce centuries of chronometric uncertainty.
    • Characterization and Dating of Saline Groundwater in the Dead Sea Area

      Avrahamov, Naama; Yechieli, Yoseph; Lazar, Boaz; Lewenberg, Omer; Boaretto, Elisabetta; Sivan, Orit (Department of Geosciences, The University of Arizona, 2010-01-01)
      This work presents an attempt to date brines and determine flow rates of hypersaline groundwater in the extremely dynamic system of the Dead Sea (DS), whose level has dropped in the last 30 yr by ~20 m. The processes that affect the carbon species and isotopes of the groundwater in the DS area were quantified in order to estimate their flow rate based on radiocarbon and tritium methods. In contrast to the conservative behavior of most ions in the groundwater, the carbon system parameters indicate additional processes. The dissolved inorganic carbon (DIC) content of most saline groundwater is close to that of the DS, but its stable isotopic composition (13CDIC) is much lower. The chemical composition and carbon isotope mass balance suggest that the low 13CDIC of the saline groundwater is a result of anaerobic organic matter oxidation by bacterial sulfate reduction (BSR) and methane oxidation. The radiocarbon content (14CDIC) of the saline groundwater ranged from 86 pMC (greater than the ~82 pMC value of the DS in the 2000s) to as low as 14 pMC. The similarity between the 14CDIC value and Na/Cl ratio of the groundwater at the DS shore and that of the 1980s DS brine indicates that the DS penetrated to the aquifer at that time. The low 14CDIC values in some of the saline groundwater suggest the existence of ancient brine in the subaquifer.
    • Chronology of the Obi-Rakhmat Grotto (Uzbekistan): First Results on the Dating and Problems of the Paleolithic Key Site in Central Asia

      Krivoshapkin, A. I.; Kuzmin, Y. V.; Jull, A. J. T. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The Obi-Rakhmat Grotto is one of the key Paleolithic sites in Central Asia. Archaeological excavations have revealed 22 strata containing archaeological materials. Lithic assemblages from all cultural layers display features similar to both late Middle Paleolithic blade industries and early Upper Paleolithic complexes in Southwest Asia and the Siberian Altai Mountains; this suggests a gradual Middle-to-Upper Paleolithic transition occurred in western Central Asia. Hominid remains found at Obi-Rakhmat (layer 16) show a mixture of archaic and modern traits. Different chronometric methods (radiocarbon, optically stimulated luminescence [OSL], U-series, and electron spin resonance [ESR]) were applied to the site's deposits. It appears that 14C dates are more reliable in terms of correspondence to the general framework of the Paleolithic of Central Asia and neighboring regions, and after critical analysis and the deletion of outliers, the upper part of the site's cultural sequence can be dated between 36,000-41,400 BP (layer 7) and ~48,800 BP (layer 14.1). The U-series dating results are less secure due to the high uranium content and the presence of detritus, which contaminates dated sediments (travertine). The OSL dating gave uniform ages for all cultural succession (~8 m of deposits), and confirms a very rapid sedimentation rate. Results of ESR dating depend greatly on the choice of uptake model. Dates calculated for the early uptake to some extent correspond to 14C data. The linear uptake chosen by Skinner et al. (2007) makes sediments very old (about 55,000-90,000 yr ago), which contradicts 14C dates and does not correspond well to the regional archaeological context.
    • Chronostratigraphic Sequence of Santuario della Madonna Cave (Calabria, Southern Italy): AMS Radiocarbon Data from a New Excavation Area

      Calcagnile, L.; Tinè, V.; Quarta, G.; D'Elia, M.; Fiorentino, G.; Scarciglia, F.; Robustelli, G.; Abate, M.; La Russa, M. F.; Pezzino, A. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The Santuario della Madonna Cave, located near Praia a Mare (Cosenza), along the northwestern coast of Calabria (southern Italy), has an impressive stratigraphy, with occupation phases spanning from the late Paleolithic to the advanced phases of the Middle Bronze Age. Recently, a new excavation area has been opened in the cave from which short-lived vegetal remains were sampled and submitted for accelerator mass spectrometry (AMS) radiocarbon dating. The aim of this study was to define an accurate chronology of the different cultural aspects and to explore the potentialities resulting from application of advanced statistical tools for 14C data analysis in such a context.
    • Comparison of 14C Ages between LSC and AMS Measurements of Choukai Jindai Cedar Tree Rings at 2600 cal BP

      Takahashi, Yui; Sakurai, Hirohisa; Suzuki, Kayo; Sato, Taiichi; Gunji, Shuichi; Tokanai, Fuyuki; Matsuzaki, Hiroyuki; Sunohara, Yoko (Department of Geosciences, The University of Arizona, 2010-01-01)
      Radiocarbon ages of Choukai Jindai cedar tree rings growing in the excess era of 14C concentrations during 2757-2437 cal BP were measured using 2 types of 14C measurement methods, i.e. liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS). The difference between the 2 methods is 3.7 +/- 5.2 14C yr on average for 61 single-year tree rings, indicating good agreement between the methods. The Choukai data sets show a small sharp bump with an average 14C age of 2497.1 +/- 3.0 14C yr BP during 2650-2600 cal BP. Although the profile of the Choukai LSC data set compares well with that of IntCal04, having a 14C age difference of 4.6 +/- 5.3 14C yr on average, the Choukai LSC 14C ages indicate variability against the smoothed profile of IntCal04.
    • Comparison of Depth Profiles of 129I and 14C Concentration in the Surface Layer of Soils Collected from Northeastern Japan

      Matsuzaki, Hiroyuki; Tsuchiya, Yoko Sunohara; Muramatsu, Yasuyuki; Maejima, Yuji; Miyairi, Yosuke; Kato, Kazuhiro (Department of Geosciences, The University of Arizona, 2010-01-01)
      129I/127I and 14C/12C depth profiles were compared for the surface 30-cm layer of soil samples (Andisols) collected from Shimokita Peninsula, northeastern Japan, in November 2005. The 129I/127I and 14C/12C profiles have a clear correlation, even taking into account that the data include samples collected from different sites with different surface histories. These results, and considering that 14C/12C can be regarded as a proxy of the original depth in stable soil, show the diversity of the 129I/127I ratio at the surface among the sites, indicating variations in the thicknesses of the layers recently removed. At one of the sampling sites (P003-1), the ∆14C value measures ~110 near the surface, which is indicative of anthropogenic 14C produced by atmospheric testing of nuclear weapons during the late 1950s and early 1960s. This site has experienced no disturbances for at least the past 50 yr. The relatively high activity of 129I (0.8 mBq/kg) and the 129I/127I ratio (7 x 10^(-9)) observed at the top layer of this site can be considered a 'representative value' when considering the anthropogenic iodine transfer from the atmosphere to the ground. The observations also support 2 separate modes of 129I migration in the soil: i.e. "topmost quick diffusion" and "subsurface relatively slow migration process." Even in the "subsurface relatively slow migration zone," the 129I/127I ratio was still orders higher than the pre-anthropogenic natural level.
    • Compound-Specific Radiocarbon Analyses of Phospholipid Fatty Acids and n-Alkanes in Ocean Sediments

      Druffel, Ellen R. M.; Zhang, Dachun; Xu, Xiaomei; Ziolkowski, Lori A.; Southon, John R.; Dos Santos, Guaciara M.; Trumbore, Susan E. (Department of Geosciences, The University of Arizona, 2010-01-01)
      We report compound-specific radiocarbon analyses of organic matter in ocean sediments from the northeast Pacific Ocean. Chemical extractions and a preparative capillary gas chromatograph (PCGC) were used to isolate phospholipid fatty acids (PLFA) and n-alkanes from 3 cores collected off the coast of California, USA. Mass of samples for accelerator mass spectrometry (AMS) 14C analysis ranged from 13-100 g C. PLFA extracted from anaerobic sediments in the Santa Barbara Basin (595 m depth) had modern ∆14C values (-20 to +54), indicating bacterial utilization of surface-produced, post-bomb organic matter. Lower ∆14C values were obtained for n-alkanes and PLFA from coast (92 m depth) and continental slope (1866 m) sediments, which reflect sources of old organic matter and bioturbation. We present a brief analysis of the blank carbon introduced to samples during chemical processing and PCGC isolation.
    • Current Pretreatment Methods for AMS Radiocarbon Dating at the Oxford Radiocarbon Accelerator Unit (ORAU)

      Brock, Fiona; Higham, Thomas; Ditchfield, Peter; Bronk Ramsey, Christopher (Department of Geosciences, The University of Arizona, 2010-01-01)
      In this paper, we summarize the main chemical pretreatment protocols currently used for AMS radiocarbon dating at the Oxford Radiocarbon Accelerator Unit, updating the protocols last described by Hedges et al. (1989).
    • Dating Human Occupation on Diatom-Phytolith-Rich Sediment: Case Studies of Mustang Spring and Lubbock Lake, Texas, USA

      Hatté, Christine; Hodgins, Gregory; Holliday, Vance T.; Jull, A. J. Timothy (Department of Geosciences, The University of Arizona, 2010-01-01)
      The Great Plains of North America have a rich archaeological record that spans the period from Late Glacial to Historic times, a period that also witnessed significant changes in climate and ecology. Chronometric dating of archaeological sites in many areas of the Great Plains, however, is often problematic, largely because charcoal and wood--the preferred materials for radiocarbon dating--are scarce in this grassland environment with few trees. Two reference archaeological sites are studied here: Mustang Spring and Lubbock Lake, Texas, USA. We carry out a geochronological approach based on a cross-study of carbon-derived data: combustion yield, 13C, 14C age differences between high temperature and low temperature released carbon, and the 14C age itself. A study that incorporates multiple approaches is required to solve issues induced by the sedimentological context, which is rich in both freshwater diatoms and phytoliths from quite different origins. Analysis of carbon-derived data allows us to draw a succession model of dry and wet episodes and to associate it with a chronological framework. In this way, we can assert that, for the Mustang Spring site, several human occupations existed from ~11 kyr BP to ~8.7 kyr BP along the 110-cm-long series with an interruption of ~150 yr that is associated with a palustrine environment between the Plainview and Firstview occupations.
    • Decadal Changes of Radiocarbon in the Surface Bay of Bengal: Three Decades after GEOSECS and One Decade after WOCE

      Dutta, Koushik; Prasad, G. V. Ravi; Ray, Dinesh K.; Raghav, Sanjeev (Department of Geosciences, The University of Arizona, 2010-01-01)
      Radiocarbon was measured in the surface seawater dissolved inorganic carbon (DIC) of the Bay of Bengal during November 2006. A meridional transect of the ∆14C in DIC was obtained from measurements in closely spaced samples collected roughly along 88E. The ∆14C of these samples ranged from 44 to 57.7 (mean 51.8 +/- 1.1, n = 12), and 38 at one station in the northern Bay of Bengal. The overall pattern of 14C distribution in DIC of surface Bay of Bengal during 2006 was roughly similar to that during the WOCE expedition of 1995. These results indicate a ∆14C decline rate of ~4 per decade since WOCE in the surface Bay of Bengal, which is much smaller compared to a decline rate of ~25 per decade observed in the 2 decades between the GEOSECS and WOCE expeditions, due to the smaller atmosphere-ocean ∆14C gradient.
    • Developing Ultra Small-Scale Radiocarbon Sample Measurement at the University of Tokyo

      Yokoyama, Y.; Koizumi, M.; Matsuzaki, H.; Miyairi, Y.; Ohkouchi, N. (Department of Geosciences, The University of Arizona, 2010-01-01)
      We have developed accelerator mass spectrometry (AMS) measurement techniques for ultra small-size samples ranging from 0.01 to 0.10 mg C with a new type of MC-SNICS ion source system. We can generate 4 times higher ion beam current intensity for ultra-small samples by optimization of graphite position in the target holder with the new ionizer geometry. CO2 gas graphitized in the newly developed vacuum line is pressed to a depth of 1.5 mm from the front of the target holder. This is much deeper than the previous position at 0.35 mm depth. We measured 12C4+ beam currents generated by small standards and ion beam currents (15-30 mu-A) from the targets in optimized position, lasting 20 min for 0.01 mg C and 65 min for 0.10 mg C. We observed that the measured 14C/12C ratios are unaffected by the difference of ion beam currents ranging from 5 to 30 mu-A, enabling measurement of ultra-small samples with high precision. Examination of the background samples revealed 1.1 mu-g of modern and 1 mu-g of dead carbon contaminations during target graphite preparation. We make corrections for the contamination from both the modern and background components. Reduction of the contamination is necessary for conducting more accurate measurement.
    • Development of an Automatic Sampling Unit for Measuring Radiocarbon Content of Groundwater

      Janovics, R.; Molnár, M.; Futó, I.; Rinyu, L.; Svingor, É.; Veres, M.; Somogyi, I.; Barnabás, I. (Department of Geosciences, The University of Arizona, 2010-01-01)
      An automatic water sampling unit was developed to monitor the radioactive emission (radiocarbon and other corrosion and fission products) from nuclear facilities into the groundwater. Automatic sampling is based on the principal of ion exchange using built-in resin columns in the submerging samplers. In this way, even the short-term emissions can be detected. According to our experiments, the 14C activity concentrations and the 13C values of the samples made by the ion exchange method are systematically underestimated compared to the real values. The carbonate adsorption feature of the sampling unit was studied under laboratory and field conditions. For this purpose, a test method was developed. The observed sampling efficiencies and additionally some carbon contamination for the sampling method itself have to be taken into consideration when we estimate the amount of 14C contamination introduced into the groundwater from a nuclear facility. Therefore, a correction factor should be made for the 14C anion exchange sampling. With the help of this correction, the results converge to the expected value.
    • Development of Graphitization of μg-Sized Samples at Lund University

      Genberg, J.; Stenström, K.; Elfman, M.; Olsson, M. (Department of Geosciences, The University of Arizona, 2010-01-01)
      To be able to successfully measure radiocarbon with accelerator mass spectrometry (AMS) in atmospheric aerosol samples, graphitization of small sample sizes ( 50 g carbon) must provide reproducible results. At Lund University, a graphitization line optimized for small samples has been constructed. Attention has been given to minimize the reduction reactor volume and each reactor is equipped with a very small pressure transducer that enables constant monitoring of the reaction. Samples as small as 25 g of carbon have been successfully analyzed, and the mass detection limit of the system has probably not been reached.
    • Development of Radiocarbon Dating Methods for Modern Bone Collagenization

      Kim, K. J.; Hong, W.; Park, J. H.; Woo, H. J.; Hodgins, G.; Jull, A. J. T. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The relationship between temperature and time required for collagenization using modern bone samples was investigated. Gelatinized samples of bone collagen were filtered to selectively collect different molecular weight fractions. The results of this study suggest that heating to 70 degrees C for a duration of 12 hr provides the optimal conditions for gelatinization.
    • Developments in the Calibration and Modeling of Radiocarbon Dates

      Ramsey, Christopher Bronk; Dee, Michael; Lee, Sharen; Nakagawa, Takeshi; Staff, Richard A. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Calibration is a core element of radiocarbon dating and is undergoing rapid development on a number of different fronts. This is most obvious in the area of 14C archives suitable for calibration purposes, which are now demonstrating much greater coherence over the earlier age range of the technique. Of particular significance to this end is the development of purely terrestrial archives such as those from the Lake Suigetsu sedimentary profile and Kauri tree rings from New Zealand, in addition to the groundwater records from speleothems. Equally important, however, is the development of statistical tools that can be used with, and help develop, such calibration data. In the context of sedimentary deposition, age-depth modeling provides a very useful way to analyze series of measurements from cores, with or without the presence of additional varve information. New methods are under development, making use of model averaging, that generate more robust age models. In addition, all calibration requires a coherent approach to outliers, for both single samples and where entire data sets might be offset relative to the calibration curve. This paper looks at current developments in these areas.
    • Dietary Habits and Freshwater Reservoir Effects in Bones from a Neolithic NE German Cemetery

      Olsen, J.; Heinemeier, J.; Lübke, H.; Lüth, F.; Terberger, T. (Department of Geosciences, The University of Arizona, 2010-01-01)
      Within a project on Stone Age sites of NE Germany, 26 burials from the Ostorf cemetery and some further Neolithic sites have been analyzed by more than 40 accelerator mass spectrometry (AMS) dates. We here present the results of stable isotope and radiocarbon measurements together with reference 14C dates on grave goods from terrestrial animals such as tooth pendants found in 10 of the graves. Age differences between human individuals and their associated grave goods are used to calculate 14C reservoir effects. The resulting substantial reservoir effects have revealed misleadingly high 14C ages of their remains, which originally indicated a surprisingly early occurrence of graves and long-term use of this Neolithic burial site. We demonstrate that in order to 14C date the human bones from Ostorf cemetery, it is of utmost importance to distinguish between terrestrial- and freshwater-influenced diet. The latter may result in significantly higher than marine reservoir ages with apparent 14C ages up to ~800 yr too old. The carbon and nitrogen isotopic composition may provide a basis for or an indicator of necessary corrections of dates on humans where no datable grave goods of terrestrial origin such as tooth pendants or tusks are available. Based on the associated age control animals, there is no evidence that the dated earliest burials occurred any earlier than 3300 BC, in contrast to the original first impression of the grave site (~3800 BC).