• A Study of Errors in 14C Dates of Peat and Sediment

      Olsson, Ingrid U. (American Journal of Science, 1986-01-01)
      It is a well-established fact that 14C dates from lake sediments are usually too old because of contamination with allochthonous material and/or due to discrete reservoir effects. The latter can occur in soft water lakes and may be examined by the 14C measurement of aqueous plants or the carbon dissolved and suspended in the water column. Some plants assimilate CO2 from the sediment. Their 14C activity is then dependent on the sediment accumulation rate and nutrients stored in the root system may also contribute misleading results. If water is filtered through ultra-fine membranes and then treated chemically, several fractions can be isolated for dating. The present study shows that the 14C activity of such fractions varies widely but with the weighted mean indicating an overall deficiency. Even the water from a raised bog evidences a 14C deficiency relative to contemporary atmospheric CO2. Charcoal from an archaeologic site and peat from corresponding layers in a nearby bog have yielded significantly different ages. The fact that the Cladium peat was from a very calcareous area is significant. The risk of contamination by younger root material is also documented.
    • Gif Natural Radiocarbon Measurements X

      Delibrias, Georgette; Guillier, M.-T.; Labeyrie, Jacques (American Journal of Science, 1986-01-01)
    • Institut Royal du Patrimoine Artistique Radiocarbon Dates XI

      Dauchot-Dehon, Michele; Van Strydonck, Mark; Heylen, Jon (American Journal of Science, 1986-01-01)
    • The Value of 210Pb in Dating Scandinavian Aquatic and Peat Deposits

      El-Daoushy, Farid (American Journal of Science, 1986-01-01)
      Sediment and peat chronologies have been further improved allowing alternative radiometric methods to complement 14C dating. Lacustrine and coastal marine sediments as well as peat deposits in various parts in Scandinavia are studied using 137Cs, 210Pb, 14C and other methods primarily to evaluate the 210Pb but also to extend the 14C chronology. The sampling sites have various sources of input and are characterized by different geochemical, depositional, and post-depositional conditions.
    • University of Lund Radiocarbon Dates XIX

      Håkansson, Sören (American Journal of Science, 1986-01-01)
    • University of Lund Radiocarbon Dates XVIII

      Håkansson, Sören (American Journal of Science, 1986-01-01)
    • University of Texas at Austin Radiocarbon Dates XV

      Valastro, S.; Mott Davis, E.; Varela, Alejandra G.; Lisk, Susan V. (American Journal of Science, 1986-01-01)