Kondariuk T. Sedimentation and facies conditions at the Pleistocene-Нolocene boundary in the Black Sea (according to foraminifera)

The Black Sea is a stratotypic region that reflects global climate change, the glacial to inter-glacial rhythms of the Eastern European Plain and mountainous areas, and transgressive-regressive events in the World Ocean. The question of the stratigraphic boundary between the Pleistocene and the Holocene is one of the keys to the development of a uniform stratigraphic and palaeographic scale for Quaternary sediments of Northern Eurasia (Yanina, 2012) and is therefore relevant. The practical significance of this issue lies in its connection with global warming and rising Black Sea levels, which bear critically on the needs of economic, social, and environmental development of the coastal zone because, without a retrospective on previous Black Sea dynamics, it will be challenging to develop a strategy for sustainable development of the region. The study of the late Pleistocene – Holocene transition in the Black Sea region began in the late nineteenth – early twentieth century by N.I. Andrusov and was continued by many researchers. All authors unanimously note the presence of Neoeuxinian and Black Sea sediments in the context of this terminal Pleistocene – early Holocene boundary, sediments that correspond to the two major stages of development in the basin. Differences exist in the proposed scenarios of transformation (gradual, catastrophic, reverse-gradual) of the Neoeuxinian basin into the modern Black Sea and the salinity of the former (either freshwater or brackish water). The main goal of the work is to determine the conditions of sedimentation and facies conditions on the border of the Pleistocene and Holocene in the Black Sea (by foraminifera). The main tasks set to achieve the goal: 1. To study the spatial distribution of modern benthic foraminifera in the surface layer of bottom sediments as an indicator of changes in the ecological conditions of sedimentation on the Black Sea shelf. 2. To study the taxonomic composition, ecological characteristics, and morphological features of shells of modern species of benthic foraminifera of the Black Sea. Identify modern complexes of benthic foraminifera, investigate their spatial distribution and construct lateral rows (meaning biotic changes with depth on the shelf as stripes running parallel to the shoreline) of foraminifera on the Black Sea shelf. 3. To use the lateral rows of modern benthic foraminifera for ecostratigraphic subdivision of bottom sediments and paleoecological reconstructions of the northwestern shelf of the Black Sea. 4. To reconstruct paleogeographic conditions and determine facies changes at the boundary of the Pleistocene and Holocene according to grain-size, lithological, and paleontological data. 5. To determine the nature of the transformation of the Late Neoeuxinian basin into the modern Black Sea on the border of the Pleistocene and Holocene.