Varve and Radiocarbon Chronology and Geochemistry of the Holocene Black Sea: Evolution of an Anoxic Basin

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The Black Sea is the only extant, relatively larger ocean basin that contains a substantial volume of anaerobic deep water. The sediments deposited in deeper water over perhaps the last 5-7 Ky are sapropelic to finely laminated and calcareous. 21-day leg of the R/V Knorr in the Black Sea in 1988 will provide an examination of the geochemical record in sediments of the timing of initiation and expansion of deep water anoia. This will be accomplished by an integrated study of box cores and large diameter gravity cores from as many as 30 stations with extensive coverage of the basin deeps. Carefully collected and preserved cores will provide a varve- calibrated timescale for the late Holocene Black Sea sequence using various photographic methods, NMRI (nuclear magnetic resonance imaging), microdensitometry, radiocarbon dating. The results will be synthesized, in cooperation with other researchers, for interpretation of the imprint of anoxia on the sediment geochemical record and the changes in productivity and accumulation rates that accompanied climate and sea level changes; statistical treatment of varve records will yield patterns of quasi-cyclic variations on timescales of 1-1000 years. All such inferences are important for interpretation of ancient laminated, organic-carbon rich strata.