Paleogeographic reconstructions of sea-level change and coastline migration on the northwestern Black Sea shelf over the past 18 kyr

Abstract

The paper discusses the main questions of Black Sea level change during the Late Pleistocene to Holocene based on high-resolution lithological-genetic and paleogeolographic analyses of the northwest Black Sea shelf and Prichernomorean limans (estuaries). Based on the study of ancient coastlines (wave-generated coastal landforms such as beaches) with radiocarbon dating, a paleogeographic map of the northwest shelf is constructed for the period from 18 to 9.2kyrBP.Statistical data processing instrumental observations show a direct and robust relationship between sea level and river discharge at intra-annual and multi-annual periodicities. Periodicity of sea-level change at different frequencies and lengths is calculated using spectral and wavelet analysis. For the periodicity investigations, analysis included the composition and salinity of bottom sediments of two cores reconstructed from the Dnieper River discharge for the past 4000 years, and data from instrumental observations for the period of 1818–2001. The results indicate statistically significant periods of sedimentation rhythms, Dnieper discharge, and sea-level change, which are defined by their common climatic and astrophysical factors of variability. There is a relationship between the generations of coastal landforms of Dzharylgach Island and the Holocene transgressive–regressive phases of the Black Sea. The data support an oscillatory model of sea-level development for the last 18kyr. Five regressions: Drevnechernomorian, Tyraian, Khadzhibeian, Olbian (Phanagorean), and Medieval, are identified in the Holocene.