THE LAST DEGLACIATION OF THE FRANZ-VICTORIA-TROUGH, NORTHERN BARENTS SEA

A study of two piston cores and a 3.5 kHz seismic profile from the Fra nz Victoria Trough provides new stratigraphic, stable isotopic and for aminiferal AMS C-14 data that help constrain the timing of ice-sheet r etreat in the northern Barents Sea and the nature of the deglacial mar ine environment. Silty diamicton at the base of each core, interpreted as till or ice-marginal debris flow, suggests that the Barents ice sh eet was grounded at the core sites (470 m water depth). Eight AMS C-14 dates on sediment overlying the diamicton indicate that the ice sheet retreated from both core sites by 12.9 ka and that postglacial sedime ntation began 10 ka ago. These dates, combined with a recently publish ed C-14 date from a nearby core, suggest that the Franz Victoria Troug h may not have been deglaciated until c. 13 ka, 2000 years later than modeled ice-sheet reconstructions indicate. In the trough, oxygen isot opic ratios in planktonic foraminifera N. pachyderma (sinistral) were 0.5-0.75 parts per thousand lower during deglaciation than after, prob ably as a result of ice-sheet and/or iceberg melting. Foraminiferal as semblages suggest that Atlantic-derived intermediate water may have be gun to penetrate the trough c. 13 ka ago.