Freshwater and Atlantic water inflows to the deep northern Barents and Kara seas since ca 13 14C ka:: foraminifera and stable isotopes

Foraminiferal stable isotopes and assemblages from Franz Victoria and St. Anna troughs provide it valuable record of freshwater and Atlantic Water flows to the northern Barents and Kara seas from deglaciation to present. The delta O-18 and delta C-13 of planktonic Neogloboquadrina pachyderma (s) and benthic Elphidium excavatum were up to 1.4 parts per thousand lower than present at ca 13, 11.5, and 10 C-14 ka (global sea-level corrected), mostly reflecting substantial freshwater inputs coincident with glacial-marine sediment deposition. Cassidulina teretis exceeded 40% of benthic foraminifera ca 13 and 10 C-14 ka, indicating subsurface penetrations of Atlantic Water. The transition to postglacial marine conditions is marked by a similar to 1 parts per thousand rise in foraminiferal delta O-18 and a sharp fall in % C. teretis soon after 10 C-14 ka. These changes imply reduced inputs of freshwater and Atlantic Water. Subsequent isotopic and foraminiferal assemblage variations reflect changing Atlantic Water conditions upstream in the Nordic Seas and shifts between the warm Fram Strait and cold Barents Sea branches of Atlantic Water. We hypothesize that glacial-isostatically induced deepening by up to similar to 150 m influenced Atlantic Water inflows to the northern Barents Sea during deglaciation and the Holocene. Thus, effects of isostatic recovery have to be factored into paleoceanographic reconstructions. (C) 2001 Elsevier Science Ltd. All rights reserved.