• Calibration of Lacustrine Sediment Ages Using the Relationship between 14C Levels in Lake Waters and in the Atmosphere: The Case of Lake Kinneret

      Stiller, Mariana; Kaufman, Aaron; Carmi, Israel; Mintz, Genia (Department of Geosciences, The University of Arizona, 2001-01-01)
      The source of endogenic organic and inorganic carbon in lacustrine sediments is the dissolved inorganic carbon (DIC) in the lake water. The relation between the radiocarbon levels of DIC in Lake Kinneret and of CO2 in the atmosphere has been investigated. The ratio of the former to the latter was found to be 0.814 +/0.013. This ratio is used for calibrating the age of the sediment according to the natural fluctuations in the atmospheric levels of 14C that occurred during the past 10,000 years.
    • 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.