Identification of the Holocene-Pleistocene boundary in the Bering Sea by diatoms

The modern diatom flora from surface sediment of the Navarin Basin region of the Bering Sea is dominated by Denticulopsis seminae and Nitzschia oceanica. D. seminae , a north boreal species, is most abundant in the deeper waters of the slope-basin regions, whereas N. oceanica , an Arctic species associated with ice cover, dominates the shallow shelf waters. Downcore studies show that these species alternate in dominance within the late Quaternary sediments. This alternation suggests responses to climatic fluctuations. The interval at which D. seminae is replaced downcore by N. oceanica in dominating the assemblage is distinct and can be correlated in cores throughout the study area as well as adjacent regions. This interval represents the transition from glacial to interglacial conditions and the Holocene-Pleistocene boundary.