Slowly accumulated (<5 cm kyr-1) and rapidly accumulated (5--20 cm kyr-1) sediments have been compared to define the initiation and termination times of the most recent sapropel (S1) in the eastern Mediterranean Sea. The Ba/Al ratio has been employed as a more persistent index of productivity than Corg. Accelerator mass spectrometry radiocarbon dating of pelagic foraminifera indicates a maximum duration for increased Ba/Al levels in S1 from ~9500--6000 (uncorrected radiocarbon convention years B.P.) in the rapidly accumulated sediments and ~9500--5300 years B.P. in the slowly accumulated sediments. This difference is ascribed to bioturbation affecting the slower accumulated S1 sediments. In the two most rapidly accumulated S1 units, from the Adriatic and Aegean Seas, there is a saddle of lower values centered on 7500 years B.P. in the Corg and Ba/Al profiles, so that the visual S1 unit appears as a doublet. Geochemical evidence indicates that this intervening period is best interpreted as an episode of increased ventilation and bottom water oxygenation during the period of sapropel accumulation. ¿ 2000 American Geophysical Union