Late- and postglacial environments in the northern Barents Sea west of Franz Josef Land LEONID POLYAK and A N D E R S SOLHEIM Polyak, L. & Solheim, A. 1994: Late- and postglacial environments in the northern Barents Sea west of Franz Josef Land. Polar Research 13(2), 197-207. A lithological and micropaleontological study of three sediment cores from the western Franz Josef Land area, two of them AMS “C dated, provides new data on the environmental evolution of the northern Barents Sea during and after the last deglaciation. Glacimarine conditions commenced in the deep Franz Victoria Trough by 13 kyr BP. and then presumably propagated into adjacent inter-island channels of Franz Josef Land. Pulses of Atlantic-derived water occurred during deglaciation and could have accelerated ice-sheet decay. Normal marine environments were established close to 10 kyr B P . Ameliorated conditions are recorded for the interval of approximately 9.5 to 5 kyr BP. After that, more severe environments existed probably associated with heavier sea-ice cover. L . Polyak, V N l l Okeangeologia, St. Petersburg. Russia; present address: Byrd Polar Research Center, The Ohio State University. Columbus, OH 43210, U . S . A . ; A . Solheim, Norwegian Polar lmtitute, P. 0. Box 5072, Majorstua. N-0301 Oslo, Norway. Introduction Despite extensive studies of the Barents Sea during the last two decades, there are major gaps in the understanding of the glacial and postglacial history of the region. The most widely studied areas are the western (e.g. E l v e r h ~ i et al. 1990; Saettem et al. 1992) and southern (Vorren et al. 1989; Gataullin et al. 1993) parts of the Barents Sea. Results from these areas show that most, if not all, of the Barents Sea was covered by an ice sheet during the last glaciation. There are indications of repeated glaciations through the Quaternary, which have eroded most of the Barents Sea shelf surface down to Mesozoic strata (Vorren et al. 1989; Saettem et al. 1992). However, the mode and timing of glaciation and deglaciation processes are still poorly understood. The northeastern part of the Barents Sea, the least accessible due to ice conditions, is the least investigated. This area, including the Franz Josef Land archipelago (Fig. l ) , could have been an important drainage basin for the Barents Sea Ice Sheet. Furthermore, the adjacent deep Franz Victoria Trough and, Saint Anna Trough are the main gateways for the water and ice exchange between the Barents Sea and the Arctic Ocean. Intensive investigations on Franz Josef Land were performed in the 1950s by Russian geologists, including studies of bottom sediments in the straits (Dibner et al. 1959). Sediment coring in the area surrounding the archipelago was pur- sued by VNII Okeangeologia in the 1970s, and the results were presented in technical reports (e.g. Kirillov et al. 1979). Foraminifera1 inves- tigation of selected cores was performed by Polyak (1982, 1985). However, these studies lack reliable chronostratigraphic framework. We have chosen three sediment cores from the Okeangeologia collection for more detailed, AMS 14C time-constrained lithological and for- aminiferal examination. In combination with other recent research efforts in the same region (Lubinsky et al. 1994; Forman et al. in press; Lubinsky et al. unpubl.) these results will allow the reconstruction of deglacial and Holocene environments of the marine area around Franz Josef Land. Physiographic features Western Franz Josef Land encompasses two large islands, Alexandra and George Land, which are separated by Cambridge Strait (Fig. 1). The latter includes a silled basin with depth exceeding 500 m. The northern parts of the islands are pres- ently ice-covered. West of the islands the large Franz Victoria Trough with depths of 500-600 m opens t o the Arctic Ocean. Franz Josef Land is composed of sedimentary 198 L . Polyak and A . Solheim 36 O 42 48 O 54 O 60 O Fig. 1. Locations and stratigraphy of the investigated cores. The three main lithological units shown are olive grey hioturbated mud, grey laminated mud, and diamicton (from top to bottom). The positions of AMS “C dates are also indicated. and igneous rocks mainly of Mesozoic age (Dibner 1957). The igneous component distin- guishes the archipelago from the surrounding Barents Sea shelf. The study area is located within the fluctuation zone of the pack-ice margin and is characterised by the multilayer hydrological structure of the Arctic Ocean (Gorshkov 1983; Treshnikov 1985). The upper layer of Arctic Water moves in a southwesterly direction and has low temperatures and salinities (mostly 34.5%) and positive temperatures. This Atlantic Water moves from Fram Strait along the northern slope of the Arctic Eurasian shelf, and penetrates the marginal troughs. The core of Atlantic Water in Franz Victoria Trough lies at 200 to 400 m. It is possible that some portion of Atlantic Water also flows into the trough from the southwest. Below the Atlantic Layer, Franz Victoria Trough is filled with saline and cold Deep Arctic water which originates from the Norwegian-Greenland Sea, and dense “winter” water which cascades from the shelf along the marginal troughs (Midttun 1985). Atlantic Water typically does not penetrate the straits of Franz Josef Land and the water column consists of the surface Arctic Water and cold, saline Local Bottom Water (Matishov et al. 1992). Materials and methods The piston cores used in this study were collected by VNII Okeangeologia in 1977 (Stations 32 and 45) and 1979 (Station 20) from the hydrographical Core 32 is from the deep silled basin in the Cam- bridge Strait. Cores 20 and 45 are from the southern part of F r a u Victoria Trough (Table 1; Fig. 1). The core material was dried, stored, and VeSSelS IVAN KIREEV and PAVEL BASHMAKOV. Late- and postglacial environments in the northern Barents Sea 199 Table 1 . Core locations. Core No. Area Lat. N Long. E Depth (m) 32 20 45 Cambridge Str. 80"4 1.07' 47"43' 360 Franz Victoria Tr. 7Y22 3 6 ' 39O43.24' 321 Franz Victoria Tr. 7 9 0 5 8 . ~ ' 41'56.9' 365 sampled several times over a period of fifteen years. The results of previous lithological studies, including heavy mineral investigations were com- piled by Kirillov et al. (1979). Additional sedi- mentological analyses of cores 32 and 45 were performed during this study at the Norwegian Polar Institute. The sampling covered the lower part of the core 45 section, and most of core 32. The grain size distribution was analysed by wet sieving of the >63 micron fractions, while the fine fractions were optically analysed in a Sedigraph. X-ray diffraction analyses (XRD) were carried out on the bulk <63 micron fraction and on the clay fraction. The analyses were undertaken on a Phillips PW1700 diffractometer with standard procedures of heating and ethyleneglycol treat- ment. Semi-quantitative calculations were done using a method described by Karlsson et al. (1978). Previous foraminiferal investigation of the cores is described by Polyak (1982, 1985). Additional sampling of core 32 was undertaken in 1992. Samples were soaked, wet sieved (0.1 mm), and concentrated by inorganic heavy liquid (KJ + CdJ) withspecificgravity 1.8 g/cm3. Ingen- eral, the number of calcareous microfossils in the 1992 samples is less than that of the previous studies, probably due to dissolution and/or dis- integration during storage. This process does not Table 2. AMS "C dates. seem to affect the percentage of foraminiferal species, allowing us to combine previous and recent results. AMS I4C dating (Fig. 1; Table 2) was performed at the Swedberg Laboratory, University of Uppsala, Sweden on four samples of calcareous foraminiferal tests from cores 32 and 45; an additional sample from core 32 was dated in the Lawrence Livermore Laboratory, U.S.A. The North Atlantic marine reservoir correction of 440 years (Mangerud & Gulliksen 1975) was subtracted from the laboratory-reported, '3C-normalised age. Results Lithology The studied cores have similar lithostratigraphies, and resemble cores described by Dibner et al. (1959). There are three main lithostratigraphic units (Fig. 1). The lower unit is composed of unstratified dark-grey stiff diamicton, identical to glacigenic diamictons described elsewhere from the Barents Sea (e.g. Elverhoi & Solheim 1983; Szttem et al. 1992; Gataullin et al. 1993). The middle unit consists mainly of light-grey soft lami- nated mud/clay. The lamination is caused by alternation of clayey and silty bands 1-20 mm Core Depth in No. core. cm Material Sample Age weight, corr., 14-C Lab. ref mg years no. 32 3 a 4 i mixed forams 5.30 4 6 0 0 s 100 TUa-180 32 172-174 I .norcrossi/helenae 9.10 9295 -t 110 TUa-181 32 244-248 mixed forams 4.00 9990 5 95 TUa-182 45 91-97 mixed forams 4.65 13,245 s 150 TUa-183 32 150-152 I.norcrossi/ 4.10 10,150 -C 70 CAMS-5561 helenae, N.labrador. 200 L . Polyak and A . Solheim cm 285 290 laminated mud diamicton Fig. 2. Thin-section of the contact between diamicton and laminated mud in core 32. thick. This type of lithofacies is characteristic of proximal glacimarine environments and results from rhythmical changes in the tidewater glacier melting regime and abscence of bioturbation (e.g. E l v e r h ~ i et al. 1983; Powell 1983; Mackiewich et al. 1984; Gorlich 1986). A photo of a thin section (Fig. 2) shows a distinct contact between the diamicton and the laminated clay in the Cam- bridge Strait. The upper unit is olive-grey bio- turbated mud, iron stained and somewhat sandy in its lower part. This type of sediment is typical for Holocene marine environments of the Barents Sea (ElverhGi & Solheim 1983; Spiridonov et al. 1992). Both core 45 from the Franz Victoria Trough and core 32 from the Cambridge Strait show distinct changes in grain size distribution and clay mineralogy at the boundaries between diamicton, laminated clay and olive grey mud (Fig. 3). The diamicton appears homogeneous with little vari- ation in grain size distribution. In both cores the sand and gravel contents drop to minimal values on transition from diamicton to deglacial sedi- ments, increasing slightly in the overlying olive grey mud with a maximum in its lower part. The silt and clay contents, however, seem to show more diverse trends. In the Cambridge Strait the clay content increases to a maximum in the deglacial sediments before it drops to post- glacial levels, which are roughly similar to those of the diamicton. The clay peak is accompanied by a silt low, while the overlying olive grey mud yields the highest silt content. In Franz Victoria Trough, on the other hand, the silt content increases in the laminated mud, while the clay content drops. There are no detailed analyses in the upper half of this unit, nor in the above postglacial part. These lithostratigraphic changes are also reflected in the mineralogy (Fig. 3). In core 32, the transition from diamicton to laminated mud shows a decrease in smectite content followed by a sharp increase. ‘The subsequent peak cor- responds t o the clay maximum in laminated mud, while the upper unit is marked by further increase in the smectite concentration. The chlorite con- tent (based on the 14A peak only) also slightly rises through the laminated mud to the postglacial level. The remaining clay minerals have their highest contents in the diamicton and eventually drop t o lower postglacial values. In the Franz Victoria Trough (core 43, smectite drops to zero at the transition from the diamicton t o laminated mud, and chlorite appears t o drop. Heavy minerals of the fine sand fraction (Kirillov et al. 1979) are dominated by either pyroxenes or clastic, originally authigenic min- erals (mainly pyrite). Pyroxenes, typical for the Franz Josef Land mineralogical province (Dibner 1957; Klenova 1960) have the highest con- centrations in postglacial sediments of the Cam- bridge Strait and decrease both down-section and towards the Franz Victoria Trough. In contrast, pyrite and other “authigenic” minerals, charac- teristic of the Mesozoic sedimentary bedrock of the central and northwestern Barents Sea (Yashin et al. 1985; E l v e r h ~ i et al. 1988), have their maxi- mum content in the Franz Victoria Trough dia- micton. Paleontology The samples, particularly those from the upper lithological unit (olive-grey muds), generally con- tain rich assemblages of calcareous benthic fora- minifers with smaller amounts of planktonic forms, and several ostracodes and molluscs (Figs. 4 and 5). Arenaceous foraminifers are practically absent, which is typical for subsurface sediments of the Arctic shelf and probably results from disintegration during early diagenesis (0stby & Nagy 1982; Spiridonov et al. 1992). Additional damage due to dry storage is highly probable. The foraminifera1 content in the diamicton is low, rarely exceeding 1-2/g of dry sediment. The Late- and postglacial environments in the northern Barents Sea 201 Grain size (%) Clay minerals (%) Heavy minerals (%) Core 32 0 20 40 60 80 1 0 0 0 20 40 60 80 1000 20 40 60 80 100 8 C Q .- ~ 3.0 c 8 4.0 5.0 Core 45 0.0 h E Q) 1.0 .& 2.0 r, R 3 . 0 Y s Gravel 1 Sand I Silt I Clay WC I llliie I Chlorite I IR I Smectite pvrOxenes I "Authigenics" I Others Fig. 3. Grain-sire and mineralogical contents in cores 32 and 45. The lithological columns indicate homogenous mud, laminated mud. and diamicton (from top to bottom). assemblage is dominated by the most common Quaternary Arctic species (see Faunal reference list, p. 207) Elphidium excauatum forma clauatum and Cassidulina renifornie, and includes "exotic" taxa of more warm-water and older faunas. The preservation varies, and some of the tests display signs of abrasion and recrystallisation. T h e same assemblage is recognized in glacigenic diamicts throughout the Barents Sea, and is considered to be reworked from older marine deposits (Hald & Vorren 1987; Hald et al. 1990; Spiridonov et al. 1992). T h e laminated mud is practically unfossiliferous in the Cambridge Strait, but contains intervals with relatively high foraminiferal abundance (up to 6S/g of dry sediment) in the Franz Victoria Trough. Most detailed study of the lower part of laminated mud in core 45 (Fig. 5 ) shows that these abundance spikes a r e separated by foraminiferal- barren intervals. T h e lowermost assemblage is dominated by E. e. clauatum and is followed by C . renijornie and/or Cassidulina teretis assemblages, the latter being sometimes associated with an increase in planktonic abundance. T h e foraminiferal assemblages in the upper- most olive-grey mud are more diverse. In the Cambridge Strait basin (Fig. 4) they are mostly dominated by lslandiella norcrossilhelenae or E. e . clauaturn. In the Franz Victoria Trough cores (Fig. 5 ) the dominant species is C . reniforme. In the middle part of all the sections there is a pronounced abundance maximum of Melonis barleeanus. and the tops a r e characterised by an increase in the E. e. clauatum content. Age control AMS I4C dating was performed on well-preserved foraminiferal tests >150 prn picked from their abundance spikes, and supposed to be in situ. 202 L . Polyak and A . Solheim 4 % Benthics b %Planktonics E.excavatum NJabrador. C.reniforme M.barleeanus 0 1 0 2 0 3 0 0 2 0 4 0 6 0 0 40 0 40 80 0 20 400 40 800 40 80 BCFlg 81- Fig. 4. Distribution of foraminifers in core 32 vs. age in I4C years. The triangles indicate dated levels. BCF/g-number of benthic calcareous foraminifers per gram of dry sediment. The legend for lithology is explained in Fig. 3 . The three Uppsala dates of the postglacial olive- grey mud in core 32 form an orderly succession, while an additional date obtained later at the Livermore Laboratory gave an age 1 ka too old relative to the other dates. N o signs of reworking to explain this ‘old’ date were found in that part of the core. Such a discrepancy cannot be under- stood without additional dating. Available dates of gravity core tops from the eastern Barents Sea sediment basins have modern age (Polyak et al. in press; Forman pers. comm.), and we assume similar age for the top of core 32. Together with the three Uppsala dates this forms a basis of an age model for core 32, obtained by linear interpolation (Fig. 4). Discussion Deglaciation record The date from the base of laminated mud in the Franz Victoria Trough (Core 45; Fig. 1) suggests that deglaciation of the trough occurred roughly at 13 kyr BP. A similar date was obtained from a Franz Victoria Trough core in deeper water t o the north (Lubinski et al. unpubl.). The accumu- lation of laminated mud is likely to have been controlled by glacier melting. The small thickness of laminated mud and absence of apparent brown coloration indicate restricted meltwater influence, which is in contrast t o the southeastern Barents Sea record (Polyak et al. in press). This implies fast deglaciation, probably due to a sea level controlled ice break-up and subsequent calving (Jones & Keigwin 1988; E l v e r h ~ i et al. 1990). At the same time, light oxygen isotope values in planktonic foraminifers from the Franz Victoria Trough laminated muds indicate reduced salinity of surface water due to local ice-sheet melting (Lubinski et al. unpubl.). The mineral composition of the diamictons indicates glacial transportation of the eroded bed- Late- and postglacial environments in the northern Barents Sea 203 4 % Benthics b E.excavatum C.reniforme C.teretis M.barleeanus I.norcrossi %Planktonics BCFIg 0 20 40 600 50 1Mx) 40 800 40 800 10 200 20 400 40 80 0 10 200 20 400 40 800 20 400 20 400 10 200 20 40 -0.4 U 8 i 0 . 8 1.2 8 Fig. 5. Distribution of foraminifers in cores 20 and 45 vs. depth in core. The crosses indicate foraminifcral-barren intervals in core 45. The legend for lithology is explained in Fig. 3 . rock material from the northwestern Barents Sea to the Franz Victoria Trough and even to t h e Franz Josef Land straits. This suggests that the main center of glaciation in the northern Barents Sea was located west of Franz Josef Land, which is consistent with the glacioisostatic rebound pat- tern (Forman et al. in press). The transition to glacimarine and marine environments increased the role of Franz Josef Land as a minerogenic source for the northern Barents Sea; this is reflected in the high pyroxene concentr-t' ions. The benthic foraminifera1 assemblage from the bottom of laminated mud (Core 45) is charac- terized by low diversity and the strong dominance of Elphidium excavatum forma clavatum, which is common in glacimarine deposits proximal to a retreating glacier (Osterman 1982; Hald et al. 1993). Successive assemblages in laminated muds are mainly dominated by Cassidulina reniforme, a second most important species in glacimarine environments (Osterman 1982; Vilks et al. 1989; Steinsund et a]. unpubl.). Foraminifera] spikes, with high contents of Cassidulina reretis and occasional planktonic foraminifers, suggest the periodic inflow of Atlantic-derived subsurface waters which could have promoted ice melting. Recent distribution of C. reretis and planktonics on the Eurasian Arctic shelf is confined t o areas influenced by Atlantic-derived water (Khusid & Polyak 1989; Steinsund et al. unpubl.). The transition from laminated clay to homo- genous olive-gray mud in the Cambridge Strait reflects a major ice retreat within the island limits and is dated t o approximately 10 kyr BP (Figs. 1 and 4). Assuming that the ice sheet break-up was bathymetrically controlled, we infer a similar time for the glacimarine-marine transition in the Franz Victoria Trough; this is confirmed with dates from the core to the north (Lubinski et al. unpubl.). Deglaciation of inter-island channels in central Franz Josef Land, as well as in eastern Svalbard, is estimated to take place roughly at the same 204 L. Polyak and A. Solheim time (Solheim 1991; Landvik et al. 1992; Forman et al. in press). Postglacial environments The early Holocene in the Cambridge Strait (Core 32) is characterized by relatively high sedi- mentation rates of 1 mm/yr, as found elsewhere in the eastern Barents Sea (Polyak et al. in press; Forman pers. comm.). A likely reason for this is residual glacier melting on the islands and/or redeposition of glacigenic material from the shal- low areas due to glacioisostatic rebound (c.f. Elverhd et al. 1989; Spiridonov et al. 1992). Up- section sedimentation rates decrease to 0.1 mm/ yr. Such low values are typical for recent Barents Sea environments with the exception of areas, proximal to actively melting glaciers ( E l v e r h ~ i et al. 1989; Polyak et al. 1994). The high content of smectite in the postglacial mud of the Cambridge Strait is typical for Hol- ocene sediments of the northern Barents Sea, in contrast to underlying glacial diamictons ( E l v e r b i et al. 1989). Its presence seems to be associated with the sediment transport by sea-ice from the Siberian shelf via the Arctic Ocean (Stein et al. 1994a). The pioneering foraminiferal assemblage in the Cambridge Strait at 10 to 9.5 kyr BP is dominated by Elphidium excaoatum forma clavatum. This species is known to be highly opportunistic, thriv- ing in stressed environments such as low and fluctuating temperatures and salinities, high tur- bidity, and short-term productivity period (Mudie et al. 1984; Hald et al. 1993). The present dis- tribution of E. e . claoatum in the Barents Sea is mainly connected with the Polar Water and appears to be associated with sea-ice cover (Khusid & Polyak 1989; Hald et al. 1993; Steinsund et al. unpubl.). Early Holocene foraminiferal assemblages in Franz Victoria Trough (Core 20; Fig. 5) are mostly dominated by Cassidulina reniforme, a common species in distal glacimarine and cold- water marine soft-bottom environments (Oster- man 1982; Mudie et al. 1984; Hald & Vorren 1987; Steinsund et al. unpubl.). Its prevalence in the early Holocene is typical for the Franz Josef Land surroundings (c.f. Lubinski et al. 1994), and is also reported elsewhere from northwestern and eastern areas of the Barents Sea (0stby & Nagy 1982; Spiridonov et al. 1992). The interval of 8.5-9.5 kyr BP in the Cambridge Strait is characterised by the dominance of lslandiella norcrossilhelenae and Nonion lab- radoricum, which typically follow E. e . clavatum and C . reniforme assemblages in post- glacial sequences and reflect ameliorated environ- mental conditions (Osterman 1982; Vilks et al. 1989; Spiridonov et al. 1992). These species pres- ently are characteristic of areas with seasonal sea-ice cover and, consequently, high seasonal organic productivity (Steinsund et al. unpubl.). N. labradoricum is also known to be a deep in- faunal species which feeds on buried organic mat- ter (Corliss 1991), and is therefore potentially indicative of high-productive environments. The predominance of 1. norcrossilhelenae and N. lab: radoricum coincides with the warmest Holocene sea-surface temperatures recorded for Svalbard (Salvigsen et al. 1992), probably marking a rela- tively warm and high-productive period for the Franz Josef Land area. The above species are also abundant ca. 5-7 kyr BP in core 32, accompanied by the peak of Melonis barleeanus. The latter is typical for mid-Holocene sediments elsewhere in the north- ern and eastern Barents Sea at depths <200m (Polyak 1982; Spiridonov et al. 1992). Highest concentrations of M . barleeanus are reported from fine-grained sediments, typically enriched with organic detritus (Corliss 1985, 1991; Korsun & Polyak 1989). Its recent distribution on the Arctic shelf is also somehow tied to Atlantic- derived water (Mudie et al. 1984; Khusid & Polyak 1989), although not necessarily to increased bottom temperatures (Steinsund et al. unpubl.). According to diatom data from the Norwegian-Greenland Sea, the strongest Atlantic inflow took place at 5-7.5 kyr BP (Koc & Jansen 1992).,A light oxygen isotope spike obtained from planktonic foraminifers, probably reflecting the maximum warming in the upper water layers, is also observed around 7 kyr BP in the Franz Vic- toria Trough and further north in the Eurasian Basin of the Arctic Ocean (Stein et al. 1994b; Lubinski et al. unpubl.). These events correspond to the position of M . barleeanus abundance maxi- mum, which might indicate the increase of Atlantic influence in the Arctic during the mid- Holocene climatic optimum. Late Holocene assemblages (after ca. 5 kyr BP in Core 32) are dominated by E. e. clauatum, which is a regional pattern for the northeastern Barents Sea and probably marks the climatic deterioration and expansion of the Polar Water Late- and postglacial environments in the northern Barents Sea 205 with perennial sea-ice in late Holocene (Spiridonov et al. 1992; Lubinski et al. 1994). Relatively high contents of C. tereris and plank- tonics in the Franz Victoria Trough at this time indicate the advection of the Atlantic-derived water as well. Thus, we suggest that at approxi- mately 5 kyr BP the recent pattern of circulation with the Polar Water at the surface and the Atlan- tic Layer below was established in the northern Barents Sea. Conclusions The deglaciation of the western Franz Josef Land area commenced at approximately 13 kyr BP in the Franz Victoria Trough and was completed by 10 kyr BP with the establishment of normal marine environments. Inflows of Atlantic-derived subsurface water into the Franz Victoria Trough likely occurred during deglaciation. The main minerogenic supply for the study area during the glaciation must have been from the northwestern Barents Sea. presumably due to sub-glacial erosion. Glacimarine and marine sedi- ments yield larger amount of the local Franz Josef Land mineral component. Another important sediment source in the Holocene seems to be associated with the sea-ice transport from the Siberian shelf through the Arctic Ocean. The foraminifera1 record indicates that the most favourable marine conditions took place at 9.5- 5 kyr BP, with the strongest Atlantic influence about 5-7 kyr BP. In the late Holocene, after 5 kyr BP, climatic environments deteriorated and the recent oceanographic pattern was developed in the northern Barents Sea. Acknowledgements. - This study is part of a collaborative research between Norsk Polarinstitutt and VNIl Okeange- ologia. Sediment cores were collected by O.V. Kirillov and N.A. Pashukova. The Norwegian Research Council for Science and Humanities (NAVF) is acknowledged for financial support under project 440-93/041. The CAMS-5561 "C date was sup- ported by S.L. Forman from NSF award DPP-9001471. D. Lubinski kindly revised the early version of the manuscript. Anders Elvcrhai hclped interpreting XKD data. Two anony- mous reviewers provided constructive critical comments. The editor was most helpful in improving the manuscript. To all these persons and institutions we offer our sincere thanks. This is Byrd Polar Research Center Contribution No. 949. References Corliss. B. 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O., Lebesbye, E., Andreassen, K. & Larsen, K.- B. 1989: Glacigenic sediments on a passive continental margin as exemplified by the Barents Sea. Mar. Geol. 85, 251-272. Yashin, D. S . , Mel’nitsky, V. Ye. & Kirillov, 0. V. 1985: Structure and composition of bottom deposits of the Barents Sea. Pp. 101-115 in: Geologicheskoe stroenie Barentseoo- Karskoao shel‘fa lGeoloeica1 structure of the Barents and 204 PP. I , . I Baffin Island, Canada: A study of foraminifera and sediments Kara Sea shelf). Sevmorgeologia, Leningrad (in Russian). Late- and postglacial environments in the northern Barents Sea 207 Faunal reference list Cassidulina reniforme NBrvang Cassidulina crassa d'Orbigny . Feyling-Hanssen et al., 1971, pl. 7, figs. 18, 19; 0stby and Nagy, 1982, pl. 3, fig. 13. Cassidulina reniforme NBrvang: Sejrup and Guil- bault, 1980, fig. 2F-K. Cassidulina teretis Tappan Cassidulina laevigata d'orbigny: @stby and Nagy, 1982, pl. 3, fig. 18. Cassidulina teretis Tappan. Mackensen and Hald, 1988, pl. 1, figs. 8-15. Elphidium excavatum forma clavatum Cushman Elphidium clauatum Cushman. Feyling-Hanssen et al., 1971, pl. 11, figs. 10-13. Elphidium excavatum (Terquem) forma clauata Cushman. Feyling-Hanssen, 1972, pls. 1, 2. Islandiella helenae Feyling-Hanssen and Buzas Islandiella helenae Feyling-Hanssen and Buzas, 1976, text figs. 1-4. Islandiella norcrossi (Cushman) Islandiella norcrossi (Cushman). Loeblich and Tappan, 1953, pl. 24, fig. 2; Feyling-Hanssen et al., 1971, pl. 8, figs. 1, 2. Melonis barleeanus (Williamson) Nonion barleeanum (Williamson). Feyling- Hanssen et al., 1971, pl. 9, figs. 15-18; 0stby and Nagy, 1982, pl. 3, fig. 15. Nonion zaandamae (van Voorthuysen). Loeblich and Tappan, 1953, pl. 15, figs. 11, 12. Nonion labradoricum (Dawson) Nonion labradoricum (Dawson). Feyling- Hanssen et al., 1971, pl. 10, figs. 1 , 2 ; 0stby and Nagy, 1982, pl. 3, fig. 17a, b.