RADIOCHRONOLOGY OF LAKE-SEDIMENTS

Sediment cores from Lakes Zurich, Constance, from the Sea of Marmara a nd from southern Turkey, northern Cyprus and eastern Spain were dated using natural Pb-210, fallout Cs-137 and cosmic-ray produced Be-7 radi onuclides. Constant activity regions in the uppermost sections of sedi ments from Lake Zurich and the Sea of Marmara were attributed to postd epositional mobility of Pb-210 in the former case and to bioturbation in the latter. A serious discrepancy exists between the Pb-210 dating of Sea of Marmara sediments and those obtained by organic carbon based methods. The elements Zn, Cu, P and Pb were enriched in the upper sec tions of the sediment cores corresponding to the last 200 years. The i ncreased metallurgical activities as a result of reforms in the Ottoma n Army during the 18th century could be the most likely cause.