• A Recent History of 14C, 137Cs, 210Pb, and 241Am Accumulation at Two Irish Peat Bog Sites: An East versus West Coast Comparison

      Gallagher, Donal; McGee, E. J.; Mitchell, P. I. (Department of Geosciences, The University of Arizona, 2001-01-01)
      Data on radiocarbon (14C), 137Cs, 210Pb, and 241Am levels in an ombrotrophic peat sequence from a montane site on the east coast of Ireland are compared with data from a similar sequence at an Atlantic peatland site on the west coast. The 14C profiles from the west and east coasts show a broadly similar pattern. Levels increase from 100 pMC or less in the deepest horizons examined, to peak values at the west and east coast sites of 117 +/0.6 pMC and 132 +/0.7 pMC, respectively (corresponding to maximal fallout from nuclear weapons testing around 1964), thereafter diminishing to levels of 110-113 pMC near the surface. Significantly, peak levels at the east coast site are considerably higher than corresponding levels at the west coast site, though both are lower than reported peak values for continental regions. The possibility of significant 14C enrichment at the east coast site due to past discharges from nuclear installations in the UK seems unlikely. The 210Pb(ex) inventory at the east coast site (6500 Bq m-2 is significantly higher than at the west coast (5300 Bq m-2) and is consistent with the difference in rainfall at the two sites. Finally, 137Cs and 241Am inventories at the east coast site also exceed those at the west coast site by similar proportions (east:west ratio of approximately 1:1.2).
    • Age Determination of Fossil Bones from the Vindija Neanderthal Site in Croatia

      Wild, Eva Maria; Paunovic, Maja; Rabeder, Gernot; Steffan, Ilse; Steier, Peter (Department of Geosciences, The University of Arizona, 2001-01-01)
      Vindija cave in Croatia is famous for the Neanderthal bones found in layer G of its sediment profile. Radiocarbon dating has been performed mainly on this layer due to the great interest in its fossils. In addition to Neanderthal remains, the sediment in layer G contains bones from the cave bear. Cave bear bones are found also in other layers of the sediment profile and offer the possibility of studying the bears' evolutionary mode. Therefore, we tried to determine the time span covered by the entire profile. The U/Th age determination method was applied to cave bear bones from different layers of the profile. For the younger part of the profile, the U/Th ages were compared with the results of the 14C and the amino-acid racemization method. The agreement of the different methods indicates that closed-system behavior can be assumed for the fossil bones from Vindija cave. From this finding it may be deduced that bones from the lower sediment layers are also closed systems and that the U/Th ages of these layers are reliable. This conclusion is corroborated by the stratigraphy of the cave profile.
    • Chronology of Soil Evolution and Climatic Changes in the Dry Steppe Zone of the Northern Caucasus, Russia, During the 3rd Millennium BC

      Alexandrovskiy, A. L.; van der Plicht, J.; Belinsky, A. B.; Khokhlova, O. S. (Department of Geosciences, The University of Arizona, 2001-01-01)
      Chrono-sequences of paleosols buried under different mounds of the large Ipatovo Kurgan, constructed during the Bronze age, have been studied to reconstruct climatic changes in the dry steppe zone of the Northern Caucasus, Russia. Abrupt climatic and environmental changes in the third millennium BC have been reconstructed, using morphological and analytical data of the soil. Based on accelerator mass spectrometry (AMS) dates of small charcoal fragments from the soil chrono-sequence, we concluded that two upper paleosols (with the clearest evidence of arid pedogenesis) developed between about 2600-2450 BC.
    • Dating of Biodeposits of Oxalates at the Arc de Berà in Tarragona, Spain

      Girbal, J.; Prada, J. L.; Rocabayera, R.; Argemi, M. (Department of Geosciences, The University of Arizona, 2001-01-01)
      This research stems from an earlier study of the lichen covering with oxalate deposits at the Arc de Berà monument. The initial objective of dating these biodeposits opened up other questions concerning the structure of these deposits and how they were formed. Some dating results gave an absolute age greater than the monument itself, which posed various hypotheses on the possible ageing mechanisms.
    • Development of Accurate and Reliable 14C Chronologies for Loess Deposits: Application to the Loess Sequence of Nussloch (Rhine Valley, Germany)

      Hatté, Christine; Pessenda, Luiz Carlos; Lang, Andreas; Paterne, Martine (Department of Geosciences, The University of Arizona, 2001-01-01)
      Due to very high accumulation rates, loess sequences are best suited archives for the continental paleoclimate of glacial periods. Accurate chronologies cannot be easily established by radiocarbon-dating, because of the lack of organic macrorests, the only material for reliable 14C dating so far. A chemical protocol is reported to extract the organic matter of loess (organic carbon content lower than 0.1% by weight) for accelerator mass spectrometry (AMS) 14C dating. Sediments were taken from the loess sequence of Nussloch, for which a large dataset of luminescence ages (TL, IRSL/OSL) is available. The 14C chronology of the organic matter extracted from loess is in good agreement with the corresponding luminescence ages. It allows high resolution correlations with climatic proxy signals (magnetic susceptibility, malacological assemblages, delta-13C on organic matter, etc.) derived from the loess sequence and global environmental proxy records.
    • High-Resolution AMS 14C Dating of Post-Bomb Peat Archives of Atmospheric Pollutants

      Goodsite, Michael E.; Rom, Werner; Heinemeier, Jan; Lange, Todd; Ooi, Suat; Appleby, Peter G.; Shotyk, William; van der Knapp, W. O.; Lohse, Christian; Hansen, Torben S. (Department of Geosciences, The University of Arizona, 2001-01-01)
      Peat deposits in Greenland and Denmark were investigated to show that high-resolution dating of these archives of atmospheric deposition can be provided for the last 50 years by radiocarbon dating using the atmospheric bomb pulse. 14C was determined in macrofossils from sequential one cm slices using accelerator mass spectrometry (AMS). Values were calibrated with a general-purpose curve derived from annually averaged atmospheric 14CO2 values in the northernmost northern hemisphere (NNH, 30 degrees to 90 degrees N). We present a through review of 14C bomb-pulse data from the NNH including our own measurements made in tree rings and seeds from Arizona as well as other previously published data. We show that our general-purpose calibration curve is valid for the whole NNH producing accurate dates within 1-2 years. In consequence, 14C AMS can precisely date individual points in recent peat deposits within the range of the bomb-pulse (from the mid-1950s on). Comparing the 14C AMS results with the customary dating method for recent peat profiles by 210Pb, we show that the use of 137Cs to validate and correct 210Pb dates proves to be more problematic than previously supposed. As a unique example of our technique, we show how this chronometer can be applied to identify temporal changes in Hg concentrations from Danish and Greenland peat cores.
    • Influence of the Bomb-Produced 14C on the Radiocarbon Concentration in the Youngest Sediments of Lake Gościąż, Central Poland

      Pawlyta, Jacek; Pazdur, Anna; Goslar, Tomasz; Hałas, Stanisław (Department of Geosciences, The University of Arizona, 2001-01-01)
      This work is a study of changes of the radiocarbon concentration in the youngest part of Lake Gościąż sediments in the calendar time scale during the last 150 years. This period includes the time of the nuclear weapons tests performed in the upper atmosphere in the 1950s, and the 1960s, which caused large release of 14C and 137Cs into the environment. On the basis of this study, the isotope dilution factor for 14C and the exchange time of carbon between the atmosphere and Lake Gościąż was estimated. The chronology of the upper part of the sediments was constructed using many interdisciplinary investigations. Among them, measurements of 137Cs in the sediment were used. An unexpected discrepancy between the previously constructed time scale and that suggested by 137Cs is observed in one of the cases.
    • Late Holocene Climatic Change in the Balkans: Speleothem Isotopic Data from Serbia

      Kacanski, Aleksander; Carmi, Israel; Shemesh, Aldo; Kronfeld, Joel; Yam, Ruth; Flexer, Akiva (Department of Geosciences, The University of Arizona, 2001-01-01)
      A detailed profile of the stable isotopes of carbon and oxygen was obtained from a speleothem (stalagmite) from the Ceremosjna Cave in eastern Serbia. The stalagmite is a low magnesian calcite that did not show any evidence of diagenetic alteration. It was precipitated under isotopic equilibrium conditions from dripping water. The age and rate of deposition was derived from six internally consistent radiocarbon dates. The initial 14C activity was determined to be approximately 80 pMC. The stalagmite appears to preserve a continuous record of calcite deposition from approximately 2300 BP until the present. Oxygen isotopic data, based upon 100 samples, are used to derive the first paleotemperature record for Serbia. A regression analysis of the all the data indicates that over the period of time that the speleothem was deposited there was a general trend of lowering of the average temperature. Superimposed upon this are significant long-term temperature fluctuations. These can be divided into four broader climatic groupings. Going from the oldest times to the present, there are two warm periods separated by a period when the temperatures fell below the temperature trend line. However, the absolute temperatures were generally above those of the more recent period that is generally characterized by the coolest climatic conditions.
    • New Data on Chronology of Landscape-Paleoclimatic Stages in Northwestern Russia During the Late Glacial and Holocene

      Arslanov, Kh A.; Savelieva, L. A.; Klimanov, V. A.; Chernov, S. B.; Maksimov, F. E.; Tertychnaya, T. V.; Subetto, D. A. (Department of Geosciences, The University of Arizona, 2001-01-01)
      Two lake and bog sediments have been thoroughly studied using palynological and radiocarbon dating methods. These are the Lembolovskoye Lake section located in the southern part of the Karelian Ithmus and the Mshinskoye bog section located in the southwestern part of the Leningrad province. The data obtained allow us to reconstruct the main features of the vegetation cover evolution, the chronology for the appearance and a real distribution of the main arboreal species from the south of the Leningrad province to the north, and to construct curves of the paleoclimate parameter changes for the area under study. Thirty-six 14C dates were obtained for the Lembolovskoye Lake section (7 m thick). According to those dates, the organic gyttja formation in the lake began 9870 +/170 BP. Spore-pollen spectra with high percentage of herbs, arborescent, and shrub-birch dated back to the Younger Dryas were found out in clay layers at a depth of 6.5 m. An appearance of spruce and alder pollen is dated at 6860 +/120 and 7510 +/150 BP, respectively. The maximal percentage of broad-leaved species falls on the first half of the Atlantic (AT-1). Thirty-two dates were obtained for the Mshinskoye bog section (6 m thick): from 60 +/70 to 9520 +/170 BP (the last date fixed the beginning of peat formation); 12 palinozones from the Preboreal to the Subatlantic were recognized there. The spruce and alder pollen began to appear 7520 +/110 and 7670 +/130 BP, respectively. The maximal amount of broad-leaved species is observed at 4690 +/80 BP. The detailed reconstruction of changes in vegetation communities during the Late Glacial and Holocene was correlated with paleoclimatic characteristics, which have been reconstructed for the section under study by using the information from a statistical method of spore-pollen data processing.
    • Radiocarbon Age of Vertisols and its Interpretation Using Data on Gilgai Complex in the North Caucasus

      Kovda, Irina; Lynn, Warren; Williams, Dewayne; Chichagova, Olga (Department of Geosciences, The University of Arizona, 2001-01-01)
      Radiocarbon dates were analyzed to assess Vertisols age around the world. They show an increase of radiocarbon age from mainly modern-3000 BP in 0-100 cm layer up to 10,000 BP at a depth 100-200 cm. Older dates reflect the age of parent material. The inversion of 14C dates seems to be a frequent phenomenon in Vertisols. A series of new dates of Vertisols from gilgai microhigh, microslope and microlow in the North Caucasus was done in order to understand the nature of this inversion. 14C age in the gilgai soil complex ranges from 70 +/45 BP in the microlow to 5610 +/180 BP in the microhigh. A trend of similar depths being younger in the microslope and microlow was found. We explain this by intensive humus rejuvenation in the microlows due to water downward flow. The older date in the microhigh represents the old humus horizon sheared laterally close to the surface and preserved by impermeable water regime. We explain inversions of 14C age-depth curves by the sampling procedures. In a narrow pit, genetically different parts of former gilgai could easily be as a genetically uniform soil profile. Because of this strong microvariability, Vertisols require sampling in a trench accounting for gilgai elements, even when gilgai are not obvious.
    • The Age of Upper Paleolithic Sites in the Middle Dnieper River Basin of Eastern Europe

      Abramova, Z. A.; Grigorieva, G. V.; Zaitseva, G. I. (Department of Geosciences, The University of Arizona, 2001-01-01)
      This paper discusses the comparative chronology of Upper Paleolithic sites in the Middle Dnieper River basin, based on archaeological and radiocarbon evidence. Three chronological periods of the development of the Upper Paleolithic are distinguished in this area. According to the data obtained, the third period is similar to the European Magdalenian, yet its economies were different. The base of the subsistence economy for Dnieperian hunters was the procurement of mammoth, while reindeer was the most important for the subsistence of European Magdalenian. The abundance of mammoths and the raw material in the form of mammoth tusks made a deep impact on both the economy and material culture of the hunters in the Dnieper River basin. The 14C dates confirm the chronological subdivision.
    • The Cave of Theopetra, Kalambaka: Radiocarbon Evidence for 50,000 Years of Human Presence

      Facorellis, Yorgos; Kyparissi, Apostolika Nina; Maniatis, Yannis (Department of Geosciences, The University of Arizona, 2001-01-01)
      The cave of Theopetra is located on the northeast side of a limestone rock formation, 3 km south of Kalambaka (21 degrees 40'46"E, 39 degrees 40'51"N), in Thessaly, central Greece. It is a unique prehistoric site for Greece, as the Middle and Upper Paleolithic, Mesolithic, and Neolithic periods are present here, bridging the Pleistocene with the Holocene. Several alternations of the climate during the Pleistocene are recognized in its stratigraphy. Among the most striking finds, two human skeletons, one from the Upper Paleolithic period after the Last Glacial Maximum and one from the Mesolithic period, should be emphasized, while in a deep Middle Paleolithic layer, the oldest human footprints, with remains of fire, were uncovered. During the 13 years of excavation, evidence of human activity suitable for radiocarbon dating was collected, such as charcoal samples from hearths and bones from the two human skeletons. The use of proportional counters for the measurement of 14C in combination with the recent improvement of the calibration curve has enabled the production of high-precision reliable ages Sixty 14C-dated samples, originating from 19 pits and from depths ranging from 0.10 m to 4.20 m, have already provided an absolute time framework for the use of the cave. The earliest limit of human presence probably exceeds 48,000 BP and the latest reaches World War II. Within these limits the 14C dating of samples from consecutive layers, in combination with the archaeological data, permits the resolution of successive anthropogenic and environmental events.
    • The Copper Age in Northern Italy

      Zoppi, U.; Fulcheri, E.; Gambari, F. M.; Hua, Q.; Lawson, E. M.; Micheletti Cremasco, M.; Venturino Gambari, M. (Department of Geosciences, The University of Arizona, 2001-01-01)
      During the period between the IVth and IIIrd millennia BC, profound changes for the ancient populations inhabiting the northern region of Italy occurred. The first Indo-European migrations were altering the ethnographic characteristics and, with the production of the first copper artifacts, the Neolithic Age was drawing to an end. The most significant testimony of that dramatic period is unquestionably the Otztal iceman. In addition, many other valuable archaeological sites, such as Alba (Cuneo, Italy), have been discovered. Although Alba produced the oldest evidence of copper objects in a Neolithic context (5380 +/40 BP; GX-25859-AMS), more recent discoveries have underlined the importance of this archaeological site. In this paper we will report on a series of radiocarbon measurements of bone remnants which, combined with morphologic, stratigraphic, paleoanthropologic, and paleopathologic studies, have allowed us to gain new insights into the culture and chronology of the European Copper Age.
    • The Varying Radiocarbon Activity of Some Recent Submerged Estonian Plants Grown in the Early 1990s

      Olsson, Ingrid U.; Kaup, Enn (Department of Geosciences, The University of Arizona, 2001-01-01)
      Eleven samples of aquatic plants from three Estonian lakes were analyzed for their radiocarbon content in a collaboration between the laboratories in Tallinn and Uppsala. delta-13C values for the actual species were compiled to allow normalization of activities measured in Tallinn without delta-13C values. The range for well determined species is usually a few per mil and the statistical uncertainty greater than or equal to 1 per mil delta-13C values vary considerably for different Potamogeton species and Myriophyllum spp. Lake Antu Sinijarv and Lake Päidre are hard-water lakes containing 300 and 200 mg HCO3-/L, respectively. One sample consisted of a carbonate crust deposited on a Ceratophyllum demersum plant in L. Antu Sinijarv. Its Delta-14C value was -147.3 +/6.7 per mil in 1990, whereas the plant had a value of -74.1 +/8.0 per mil (delta-13C = -35.0 per mil). The same species in L. Päidre had a Delta-14C value of +8.0 +/8.8 per mil (delta-13C = -25.2 per mil) in 1992. Other species in L. Päidre contained more 14C, from a Delta-14C value of about +30 per mil to about +155 per mil, the latter value measured in Tallinn on floating leaves of Nuphar lutea, close to that of the contemporaneous atmospheric CO2. In the third lake, Lake Punso, containing >30 mg HCO3-/L, the stems of Nuphar lutea exhibited in 1990 a memory effect: the activity, Delta-14C = 209.6 +/10.3 per mil, significantly exceeded that of the contemporaneous atmospheric CO2. However, the floating leaves of the same plant had the Delta-14C value 143.1 +/10.0 per mil, close to the atmospheric 14C level in 1990. The memory is explained by nutrients stored in the root stock, used when the growth starts.
    • Towards a Radiocarbon Chronology of the Late-Glacial: Sample Selection Strategies

      Walker, M. J. C.; Bryant, C.; Coope, G. R.; Harkness, D. D.; Lowe, J. J.; Scott, E. M. (Department of Geosciences, The University of Arizona, 2001-01-01)
      This paper outlines a dating program designed to test the reproducibility of radiocarbon dates on different materials of Late-Glacial age (plant macrofossils, fossil beetle remains, and the "humic" and "humin" chemical fractions of limnic sediments) using a combination of radiometric (beta counting) and accelerator mass spectrometry (AMS) techniques. The results have implications for the design of sampling strategies and for the development of improved dating protocols, both of which are important if a high-precision 14C chronology for the Late-Glacial is to be achieved.