YOUNGER DRYAS POLLEN RECORDS FROM SVERDRUP ISLAND (KARA SEA)

Sverdrup Island, in the Kara Sea, is currently occupied by polar deser t vegetation. The analysis of Allerod deposits indicates a climate dri er than presently, with increased summer and decreased winter temperat ures. The relative scarcity of distal pollen indicates that mainland s ource areas were located further south than at present. Younger Dryas cooling and increased dryness resulted in an increase of the proportio ns of Artemisia, Chenopodiaceae and Salix pollen, and in the extent of Sphagnum mosses. Preboreal time was marked by warmer, more humid cond itions, with dwarf birches, Ericales and possibly Alnus fruticosa. The increased proportions of distally-derived arboreal birch pollen, coup led with the local component of the assemblages, indicates that the ea rly Holocene represented the climatic optimum, initiated by the openin g of the Arctic Ocean. Subsequent climate fluctuations were muted on S verdrup Island, due to the development of microclimatic conditions ass ociated with an oceanic regime. (C) 1997 INQUA/Elsevier Science Ltd.