Holocene paleoceanography of the northern Barents Sea and variations of the northward heat transport by the Atlantic Ocean. Boreas, Vol. 30, pp. 2-16. Oslo. ISSN 0300-9483.Foraminiferal assemblage s were studied in northern Barents Sea core ASV 880 along with oxygen and carbon isotope measurement s in planktoni c (N. pachyderm a sin.) and benthic (E. clavatum ) species. AMS C-14 measurements performed on molluscs Yoldiella spp. show that this core provides a detailed and undisturbe d record of Holocene climatic changes over the last 10 000 calendar years. Surface and deep waters were very cold (< 0°C) at the beginning of the Holocene. C. reniforme dominated the highly diverse benthic foraminiferal assemblage . From 10 to 7.8 cal. ka BP, a warming trend culminated in a temperature optimum, which developed between 7.8 and 6.8 cal. ka BP. During this optimum, the input of Atlantic water to the Barents Sea reached its maximum. The Atlantic water mass invaded the whole Franz Victoria Trough and was present from subsurface to the bottom. No bottom water, which would form through rejection of brine during winter, was present at the core depth (388 m). The water strati cation was therefore greatly reduced as compared to the present. An increase in percentag e of I. helenae/norcrossi points to long seasonal ice-free conditions. The temperature optimum ended rather abruptly, with the return of cold polar waters into the trough within a few centuries . This was accompanie d by a dramatic reductio n of the abundanc e of C. reniforme. During the upper Holocene, the more opportunisti c species E. clavatum became progressivel y dominant and the water column was more strati ed. Deep water in Franz Victoria Trough containe d a signi cant amount of cold Barents Sea bottom water as it does today, while subsurface water warmed progressivel y until about 3.7 cal. ka BP and reached temperatures similar to those of today. These long-term climatic changes were cut by several cold events of short duration, in particula r one in the middle of the temperatur e optimum and another, which coincides most probably with the 8.2 ka BP cold event. Both long-and short-ter m climatic changes in the Barents Sea are associate d with changes in the ow of Atlantic waters and the oceanic conveyor belt. Jean-Claud e Duplessy

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[1] We measured the oxygen isotopic composition of planktonic and benthic foraminifera in three cores collected at key positions to reconstruct the paleoceanography of the Barents Sea: core ASV 880 on the path of the northern branch of Atlantic water inflowing from the Arctic Ocean, core ASV 1200 in the central basin near the polar front, and core ASV 1157 in the main area of brine formation. Modern seawater d 18 O measurements show that far from the coast, d 18 O variations are linearly linked to the salinity changes associated with sea ice melting. The foraminifer d 18 O records are dated by 14 C measurements performed on mollusk shells, and they provide a detailed reconstruction of the paleoceanographic evolution of the Barents Sea during the Holocene. Four main steps were recognized: the terminal phase of the deglaciation with melting of the main glaciers, which were located on the surrounding continent and islands, the short thermal optimum from 7.8 ka B.P. to 6.8 ka B.P., a cold mid-Holocene phase with a large reduction of the inflow of Atlantic water, and the inception of the modern hydrological pattern by 4.7 ka B.P. Brine water formation was active during the whole Holocene. The paleoclimatic evolution of the Barents Sea was driven by both high-latitude summer insolation and the intensity of the Atlantic water inflow.

Holocene paleoceanography of the northern Barents Sea and variations of the northward heat transport by the Atlantic Ocean. Boreas, Vol. 30, pp. 2-16. Oslo. ISSN 0300-9483.Foraminiferal assemblage s were studied in northern Barents Sea core ASV 880 along with oxygen and carbon isotope measurement s in planktoni c (N. pachyderm a sin.) and benthic (E. clavatum ) species. AMS C-14 measurements performed on molluscs Yoldiella spp. show that this core provides a detailed and undisturbe d record of Holocene climatic changes over the last 10 000 calendar years. Surface and deep waters were very cold (< 0°C) at the beginning of the Holocene. C. reniforme dominated the highly diverse benthic foraminiferal assemblage . From 10 to 7.8 cal. ka BP, a warming trend culminated in a temperature optimum, which developed between 7.8 and 6.8 cal. ka BP. During this optimum, the input of Atlantic water to the Barents Sea reached its maximum. The Atlantic water mass invaded the whole Franz Victoria Trough and was present from subsurface to the bottom. No bottom water, which would form through rejection of brine during winter, was present at the core depth (388 m). The water strati cation was therefore greatly reduced as compared to the present. An increase in percentag e of I. helenae/norcrossi points to long seasonal ice-free conditions. The temperature optimum ended rather abruptly, with the return of cold polar waters into the trough within a few centuries . This was accompanie d by a dramatic reductio n of the abundanc e of C. reniforme. During the upper Holocene, the more opportunisti c species E. clavatum became progressivel y dominant and the water column was more strati ed. Deep water in Franz Victoria Trough containe d a signi cant amount of cold Barents Sea bottom water as it does today, while subsurface water warmed progressivel y until about 3.7 cal. ka BP and reached temperatures similar to those of today. These long-term climatic changes were cut by several cold events of short duration, in particula r one in the middle of the temperatur e optimum and another, which coincides most probably with the 8.2 ka BP cold event. Both long-and short-ter m climatic changes in the Barents Sea are associate d with changes in the ow of Atlantic waters and the oceanic conveyor belt. Jean-Claud e Duplessy