• Radiocarbon, Volume 33, Number 3 (1991)

      Department of Geosciences, The University of Arizona, 1991-01-01
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      Department of Geosciences, The University of Arizona, 1991-01-01
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      Department of Geosciences, The University of Arizona, 1991-01-01
    • Radiocarbon Announces the Publication of the Following Special Issues:

      Department of Geosciences, The University of Arizona, 1991-01-01
    • Radiocarbon – Price List

      Department of Geosciences, The University of Arizona, 1991-01-01
    • Notice to Readers and Contributors

      Department of Geosciences, The University of Arizona, 1991-01-01
    • From the Editor

      Long, Austin (Department of Geosciences, The University of Arizona, 1991-01-01)
    • Associate Editors

      Department of Geosciences, The University of Arizona, 1991-01-01
    • A Special Issue is Forthcoming

      Broecker, Wally; Kra, Renee (Department of Geosciences, The University of Arizona, 1991-01-01)
    • University of Granada Radiocarbon Dates V

      Gonzalez-Gomez, Cecilio; Sanchez-Sanchez, Purificacion (Department of Geosciences, The University of Arizona, 1991-01-01)
    • University of Barcelona Radiocarbon Dates I

      Mesires, J. S.; Rauret, Gemrna; J, J. F. (Department of Geosciences, The University of Arizona, 1991-01-01)
    • Tartu Radiocarbon Dates XII

      Ilves, Evald (Department of Geosciences, The University of Arizona, 1991-01-01)
    • Shell Hash Dating and Mixing Models for Palimpsest Marine Sediments

      Roy, Peter S. (Department of Geosciences, The University of Arizona, 1991-01-01)
      The dating of palimpsest marine sediments using broken shell fragments (shell hash) is considered to be a necessary but unreliable technique because of the mixed age of the fragments. An analysis of geological mixing models and radiocarbon data on shell hash from sandy sediments on the southeast Australian coast and shelf are used to examine the possibility for simulating the depositional processes, and thus, to better understand the age structure of the deposits.
    • Radiocarbon in Seawater and Organisms from the Pacific Coast of Baja California

      Druffel, Ellen R. M.; Williams, Peter M. (Department of Geosciences, The University of Arizona, 1991-01-01)
      Radiocarbon was measured in dissolved inorganic carbon (DIC) and living organisms collected off the west coast of Baja California in October 1980. Samples from three locations were examined. Delta-14C of DIC at the southernmost station was higher than those further north, which reflects reduced upwelling in the southern region. Crabs and anchovies had Delta-14C values significantly lower than surface DIC Delta-14C, indicating the incorporation of ‘older', sediment-derived carbon sources from their diets. Comparisons are made between our DIC Delta-14C measurements and those obtained during other cruises and at a coastal site, from 1959 through 1987. Two distinct time histories of DIC Delta-14C are apparent for the post-bomb period: 1) a lower Delta-14C curve for sites close to the coast influenced by enhanced coastal upwelling; and 2) a higher Delta-14C curve for sites further offshore within the California Current.
    • Radiocarbon Updates

      Department of Geosciences, The University of Arizona, 1991-01-01
    • Physical Research Laboratory Radiocarbon Dates VI

      Agraival, D. P.; Kusurngar, Sheela; Yadava, M. G. (Department of Geosciences, The University of Arizona, 1991-01-01)
    • Lithium Contamination in AMS Measurements of 14C

      Loyd, D. H.; Vogel, J. S.; Trumbore, Susan E. (Department of Geosciences, The University of Arizona, 1991-01-01)
      High count rates of lithium ions in an AMS measurement system for 14C were traced to the lithium content in the quartz tubes used in the graphitization of the samples. The lithium contamination was nearly eliminated by the use of borosilicate glass reaction tubes at a lower reaction temperature. The ion beam current and the measurement precision of the isotope ratio were not affected.
    • Letters to the Editor

      Broecker, W. S.; Donahue, Doug; Nisbet, E. G.; Nelson, Erle (Department of Geosciences, The University of Arizona, 1991-01-01)
    • Late Quaternary Pteropod Preservation in Eastern North Atlantic Sediments in Relation to Changing Climate

      Ganssen, G. M.; Troelstra, Simon R.; van der Borg, Klaas; De Jong, A. M. F. (Department of Geosciences, The University of Arizona, 1991-01-01)
      AMS 14C measurements on pteropod shells from eastern North Atlantic deep-sea cores reveal distinct periods of aragonite preservation during the last 16,000 years. Most preservation spikes coincide with documented periods of climatic change on a scale of 2 x 101 to 2 x 103 years.
    • Laboratories

      Department of Geosciences, The University of Arizona, 1991-01-01