POSTGLACIAL EVOLUTION OF THE EASTERN KARA SEA DERIVED FROM A SEDIMENT CORE OFF THE NORTHERN TAYMYR PENINSULA, CENTRAL RUSSIAN ARCTIC

During the past decades, much progress has been made in the reconstruction of the Siberian Shelf´s postglacial evolution in the Laptev Sea and in the Kara Sea. However, comparatively little attention was paid to the Vilkitsky Strait between the Taymyr Peninsula and the Severnaya Zemlya Archipelago, which today is an important oceanic gateway between the Kara and Laptev Seas. Marine sediment core PS2719-1 originates from west of the entrance to the Vilkitsky Strait and thus, represents a key sedimentary record for the reconstruction of the postglacial shelf evolution of the eastern Kara Sea. Sedimentological, chronological, geochemical, mineral magnetic and micropaleontological data were used to investigate the sedimentary evolution of the area in unprecedented detail. Accordingly, four phases of sedimentation are identified, showing a complex interplay of sea-level rise and input from the Yenisei and Taymyr Rivers. Sedimentation likely commenced directly after regional deglaciation prior to 13.6 cal ka BP. Basal sediments are coarse grained and rich in terrestrial organic matter, which points to shelf erosion as the dominating sedimentation process. Around 13.6 cal ka BP Yenisei River water masses reached the area, causing a shift in heavy mineral assemblages and a distinct peak in magnetic susceptibility.

This phase was followed by increased sedimentation rates during the early Holocene. The sediments are characterized by high terrestrial organic matter accumulation, a fine-grained composition, and a heavy mineral assemblage reflecting the sediment source on the Taymyr Peninsula. Furthermore, these sediments indicate at least partly glacial ice cover on the northern Taymyr Peninsula during the Early Holocene. As a result, the high sediment supply is interpreted to be related to Lake Taymyr and the opening of an ice dam in the Lower Taymyr River area. The transition to modern conditions commenced already around 8.5 cal ka BP and were fully established at ca. 5 cal ka BP, being characterized by more marine conditions and a strong influence of the Yenisei River.