Palinostratigraphy of glaciomarine and marine sedimentsof the Barents Sea

Abstract

By combining the palynologic, lithologic and published geophysical data a stratigraphic division into three main sedimentary units representing major stages in the development of post-glacial sedimentary environments in the southeastern and central parts of the Barents Sea has been substantiated. Unit 3 presumably characterizes proglacial environments of the early deglaciation (tentatively older than 15 ka) and is represented by relatively fine-grained, dark grey sediment matrix with numerous coarse terrigenous clasts. The unit contains low in diversity and concentration pollen assemblage, which is dominated by reworked, mostly Mesozoic pollen and sparse dinocysts of a cryophylic species Islandinium var. minutum. Unit 2 represents later deglacial conditions (estimated ca 12-15 ka) and is composed of finely laminated, grey to brownish sandy/silty muds with coarse clasts interpreted as iceberg-rafted debris. It is characterized by pollen assemblage zone with a low concentration of plant remains, a significant proportion of reworked pre-Cenozoic microfossils and club mosses among spores as well as a high percentage of dwarfBetula, Poaceae and Artemisia Islandinium var. minutum dominates among the aquatic palynomorphs. Unit 1, younger than ca 12 ka, is composed of soft, olive-grey mud with traces of bioturbations and spots of hydrotroilite at the top or sandy-silty mud within the South-Novozemelskii Trough and sand with inclusions of pebbles and broken shells within the Kanin Plateau. Three pollen assemblage zones correspond to it. They are marked by a high percentage of birch and pine pollen, an increased share of pollen of spruce and alder, as well as Sphagnum mosses and ferns. Constant presence of sparse pollen of broad-leaved plants in combination with peak values of Operculodinium centrocarpum and Spiniferites sp. testify the enhancement of Atlantic water influence upon the studied regions.