SEDIMENT ACCUMULATION IN THE CENTRAL WESTERN BLACK SEA OVER THE PAST 5100 YEARS

The postdepositional particle flux (accumulation rate) over the last 5100 years was studied in the anoxic sediment units I and II from the central western Black Sea. Deposition of unit II (sapropel) in the deep Black Sea basin was divided further into two subunits. The beginning of the deposition of the sapropel in the Black Sea (5100-3100 years B. P., subunit IIb) was characterized by higher organic carbon accumulation rates due largely to higher primary production. Accumulation rates of lithogenic matter were at a minimum compared to younger units. During the subsequent 2100 years (3100-1000 years B. P., subunit IIa) organic carbon accumulation rates decreased considerably while accumulation rates of lithogenic matter increased to the present level. At 1000 years B. P. (unit I), total mass accumulation rates increased by a factor of 3. This increase was largely a result of an increase in carbonate accumulation rates by a factor of 11, which was caused by the rapid appearance of Emiliania huxleyi in the Black Sea. Higher carbonate accumulation rates in unit I are mainly the cause for the considerably lower organic carbon content compared to unit II, since the organic carbon accumulation rate in unit I did not decrease. General correspondence of accumulation rates of lithogenic matter in different cores through time suggests over regional long-term (100-year scale) climatic effects on the terrigenous particle supply to the Black Sea.