ИСТИНА

The object of the study is the Late Cretaceous sequences of Crimea-North Caucasus and Mangyshlak peninsula. 300 samples were analysed for foraminifers and radiolarians. The water depth model is based on the planktonic/benthic ratio and on the analysis of planktonic foraminiferal associations. Deep-water basin existed in Crimea-Caucasus that is confirmed with high P/B ratio and high per cent of deep-water planktonic taxa (k-strategists). The shallow water environment may be postulated for successions in Mangyshlak (low P/B ratio and high per cent of shallow water planktonic species, r-strategists). Anoxic events, radiolarian bloom and enrichment of sediments in organic carbon existed on the Cenomanian-Turonian boundary on the all studied area. Thickings of the siliceous skeletons in the major cephalic segment of Nassellaria on the Cenomanian-Turonian boundary reflect environmental stress (oxygen content and others). The presence of numerous representatives of genus Theocapsomma and Cryptamphorella and Excentrosphaerella at Cenomanian-Turonian and Santonian-Campanian intervals was recorded and it also can be explained by good adaptation of these skeleton types to sharp changes in water media (Anoxia and Campanian cooling-time).