• On the 14C and 39Ar Distribution in the Central Arctic Ocean: Implications for Deep Water Formation

      Schlosser, Peter; Kromer, Bernd; Östlund, Gote; Ekwurzel, Brenda; Bönisch, Gerhard; Loosli, H. H.; Purtschert, Roland (Department of Geosciences, The University of Arizona, 1994-01-01)
      We present Delta-14C and 39Ar data collected in the Nansen, Amundsen and Makarov basins during two expeditions to the central Arctic Ocean (RV Polarstern cruises ARK IV/3, 1987 and ARK VIII/3,1991). The data are used, together with published Delta-14C values, to describe the distribution of Delta-14C in all major basins of the Arctic Ocean (Nansen, Amundsen, Makarov and Canada Basins), as well as the 39Ar distribution in the Nansen Basin and the deep waters of the Amundsen and Makarov Basins. From the combined Delta-14C and 39Ar distributions, we derive information on the mean "isolation ages" of the deep and bottom waters of the Arctic Ocean. The data point toward mean ages of the bottom waters in the Eurasian Basin (Nansen and Amundsen Basins) of ca. 250-300 yr. The deep waters of the Amundsen Basin show slightly higher 3H concentrations than those in the Nansen Basin, indicating the addition of a higher fraction of water that has been at the sea surface during the past few decades. Correction for the bomb 14C added to the deep waters along with bomb 3H yields isolation ages for the bulk of the deep and bottom waters of the Amundsen Basin similar to those estimated for the Nansen Basin. This finding agrees well with the 39Ar data. Deep and bottom waters in the Canadian Basin (Makarov and Canada Basins) are very homogeneous, with an isolation age of ca. 450 yr. Delta-14C and 39Ar data and a simple inverse model treating the Canadian Basin Deep Water (CBDW) as one well-mixed reservoir renewed by a mixture of Atlantic Water (29%), Eurasian Basin Deep Water (69%) and brine-enriched shelf water (2%) yield a mean residence time of CBDW of ca. 300 yr.
    • Pollen Concentrate Preparation from Highly Organic Holocene Peat and Lake Deposits for AMS Dating

      Richardson, Fiona; Hall, Valerie A. (Department of Geosciences, The University of Arizona, 1994-01-01)
      Many of the problems inherent with conventional 14C dating of lake and peat deposits are eliminated by AMS dating of pollen concentrates. Published work describes production of pollen concentrates through expulsion of most of the deposit matrix by repeated deflocculation, selective sieving and final retention of the largest subfossil pollen taxa. Less suited to pollen concentrate production are the highly organic peats and lake muds from the British Isles and Europe. In this study we tested the combined effectiveness of physical, chemical and microbiological degradation and elimination techniques for pollen concentrate production on highly organic peats and a lake mud. We also reviewed methods of enhancing concentrations of smaller sub-fossil pollen grains. Here we present a novel method of assessing AMS dating precision of pollen concentrates by comparing their calibrated dates with a volcanic event of known historical age.
    • Prehistoric Colonization of Northeastern Siberia and Migration to America: Radiocarbon Evidence

      Kuzmin, Yaroslav V. (Department of Geosciences, The University of Arizona, 1994-01-01)
      This review of radiocarbon dates from northeastern Siberian Paleolithic sites provides data that can be applied to establishing a chronology of human settlement, and that can provide a rough estimate of the timing of the initial peopling of the New World.
    • Radiocarbon Dating of the Stone and Bronze Age Sites in Primorye (Russian Far East)

      Kuzmin, Yaroslav V.; Orlova, Lyobov A.; Sulerzhitsky, Leopold D.; Jull, A. J. T. (Department of Geosciences, The University of Arizona, 1994-01-01)
    • Radiocarbon Dating Sites of Northwest Russia and Latvia

      Zaitseva, G. I.; Popov, S. G. (Department of Geosciences, The University of Arizona, 1994-01-01)
      We describe applications of radiocarbon dating used for establishing a chronology of archaeological sites of the Novgorod region at the end of the first millennium AD. We have 14C-dated known-age tree rings from sites in Latvia and ancient Novgorod, northwest Russia, as well as charcoal and wood from Novgorod. Calendar ages of 14C-dated tree rings span the interval, AD 765-999. We used the Groningen calibration program, CAL15 (van der Plicht 1993) to calibrate 14C ages to calendar years. Comparisons between 14C results and archaeological data show good agreement, and enable us to narrow the calendar interval of calibrated 14C determinations.
    • Radiocarbon Updates

      Department of Geosciences, The University of Arizona, 1994-01-01
    • Radiocarbon, Volume 36, Number 3 (1994)

      Department of Geosciences, The University of Arizona, 1994-01-01
    • Subject Index – Volume 36, 1994

      Department of Geosciences, The University of Arizona, 1994-01-01
    • Ulrich Siegenthaler, 1941-1994

      Loosli, Heinz Hugo (Department of Geosciences, The University of Arizona, 1994-01-01)