Ohiienko O. The Upper Quaternary sedimentary paleoenvironments using diatoms, the Western Antarctica

The dissertation is devoted to research of the Late Pleistoce-Holocene paleoenvironment changes on diatom taxonomic diversity in marine surface deposits of the Argentinean Islands water area near the 'Academician Vernadsky' Ukrainian Antarctic Station, the Western Antarctic. The research is aimed at studying the Holocene depositional environments based on diatom analysis. The diatom technique allowed to determine the dependence of diatom taxonomic composition and ecological structure on major paleoenvironmental factors according to the shelf morphological structure of the Antarctic Peninsula North-Western shelf. On silicious microplanctonic data the North-Western shelf biofacial and paleohydrological conditions in the surface bottom sediment formation have been defined. The research of the Holocene transformation of marine sedimentary conditions near Antarctic Peninsula is important owing to the rapid Late Quaternary climate changes. Due to the taxonomic composition and ecological structure of diatom assemblages at a west of Elephant Island, the age of core deposits accumulation was determined as the Late Holocene (not early 2,400 yr), neoglacial stage. The study of silicious fossils from the sufface sediments of the Southern Scotia Sea it is revealed the combination of Late-Holocene and Miocene species in complexes, due to the abundance of inclusions of Middle Miocene diatoms in the rock. Age of re-deposition, iceberg transporters and ways of transportation are determined. Based on the paleostream's direction, it is suggested possible localization of diatomite layers.