Concordant 210Pb and 137Cs ages of black sea anoxic unconsolidated sediments

Two independent geochronologic radiometric methods: 137Cs and 210Pb were used to determine the sedimentation rate and subsequently to date the oldest sediments of a 50 cm core containing unconsolidated sediments collected at a depth of 600 m below sea surface in the anoxic zone of the Western Black Sea, off the Romanian town of Constanta. Both methods gave coincident value within experimental uncertainties of 0.42±0.20 mm·y−1 for 137Cs and 0.49±0.03 mm·y−1 in the case of 210Pb, within the Constant Initial Concentration model, which gave for the lower most sediments an age of 1.00±0.01 ka. The constant sedimentation model as well as the possible causes of observed discrepancy between experimental uncertainties are discussed.