Upper Quaternary water level history and sedimentation in the northwesternBlack Sea

A regional water level curve for the northwestern Black Sea covering lowsta nds of the past 900 ka has been inferred from shelf terraces and coastal on laps identified in seismic data. Corrections for sediment compaction, isost atic response to sediment load and thermal subsidence were included. A wate r level lowstand of -151 m was found for the last glaciation, ca 30 m lower than the global sea level stand at the Last Glacial Maximum. Water level c ould develop independently in the Black Sea due to its isolation from the g lobal oceans when the water level of the Black Sea was lower than its outle t. In addition, a deepsea fan complex in the northwestern Black Sea was invest igated by seismic reflection, showing that it can be divided into the Danub e fan and the Dniepr fan (also fed by the rivers Dniestr and Southern Bug). Eight seismic sequences were distinguished in the northwestern Black Sea a nd their thicknesses and facies distributions mapped. The two lowermost seq uences consist mainly of unchannelized mass transport deposits (slumps, sli des, debris flows), while the six upper sequences with their typical channe l-levee systems as well as overbank and mass transport deposits constitute the deepsea fan complex. Correlation of fan development with the regional w ater level curve yields an inferred age of ca 900 ka BP for the Danube fan; development of the Dniepr fan started probably about 100 ka later. Compute d average sedimentation rates range between 1.19 and 2.19 m/ka for the Danu be fan and between 1.07 and 2.03 m/ka for the Dniepr fan. The corresponding rates for sediment accumulation are 68-141 t/a and 41-82 t/a. Mean denudat ion rates in the drainage area are computed to be 0.027-0.105 mm/a and 0.01 7-0.127 mm/a, respectively. (C) 2000 Elsevier Science B.V. All rights reser ved.