LATE-PLEISTOCENE – HOLOCENE SEDIMENT ACCUMULATION IN THE NORTHWESTERN BLACK SEA SHELF

Abstract

Main purpose of this study is characterization of the facies and paleogeographical features of sedimentforming processes. The subject of the study is the Late-Pleistocene – Holocene bottom sediments of the Northwestern Black Sea shelf. Methodology includes standard statistical calculations of the thicknesses of bottom marine sediments and their description. Finding:the Late-Pleistocene-Holocene bottom sediments facies’ formation was determined by the repeated coastline position changes. The study area recent underwater landscapes were formed during the Holocene transgression, when subaerial flats were flooded. The land facies within the study area are represented by fluvial, eolian and eolian-deluvil genetic types of sediments. The basin underwent significant environmental transformations after reconnectionwith the Mediterranean Sea and within the study are such stages as lacustrine, brackish water and marine can be traced. Sediment forming processes were determined by the presence of limans during the early Holocene period, which were situated lower than the modern coastline and corresponded to the paleoriver valleys’ position. Considerable sediment thicknesses (from5 to 10 m) were accumulating during this time. The Odessa bay, Dnieper-Bug liman, Dniester coastal waters, paleo-Dniester, Dnieper depression and paleo-Sarata valley are characterized by the high rates of deposits accumulation. Thereby, sediment forming environments in the study area experienced gradual transformation due to considerable riverin waters inflow that is why brackish-water mollusks of Caspian type are wide spread even after the salt Mediterranean water entered the basin. Paleogeographical features such as coastline position and the basin bottom relief influenced strongly the bottom facies disposition and its thicknesses.