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Combined records of biomarkers and pigments and the correlation of core OCE2019-HR7-GC with the GISP2 ice core. From bottom to top: summary of IP 25 concentration, calculated P B IP 25 and P D IP 25 indices, percentage of C 37:4 alkenone (%C 37:4 ), brassicasterol concentration, dinosterol concentration, Σchloropigments-a concentration, carotenoid concentration, total C 37 alkenone (ƩC 37 ), reconstructed alkenone-derived sea surface temperature (U K′ 37 -SST), bottom water temperature (Mg/Ca-BWT), summer insolation at 77 • N (black line) and δ 18 O of the GISP2 core (orange line) (Grootes et al., 1993). Foraminiferal zones (zone I-IV) are shown on the top of the panels. Orange shading denotes the Holocene Thermal Maximum. Red triangles next to the x-axis indicate radiocarbon dates. LOD: limit of detection. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
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While general trends in the inflow of Atlantic Water (AW) to the European Arctic over the present interglacial (the Holocene) are well known, regional changes in climate and the AW current and subsequent environmental responses are less well established. In particular, there is only limited knowledge on the development of ocean currents after the l...
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... spring sea ice biomarker IP 25 (average 5.3 ng/g d.w) and the terrigenous biomarkers β-sitosterol (average 0.5 μg/g d.w) and campesterol (average 0.3 μg/g d.w) are high in the base of HR7 (zone I as defined by the foraminifera assemblages) (Figs. 5 and 6). In zone II, the terrigenous biomarkers ß-sitosterol (average 0.34 μg/g d.w) and campesterol (average 0.14 μg/g d.w) are relatively low. Out of the 10 samples analysed in zone II, 4 yielded IP 25 values (between 9.5 and 7.75 (Fig. 5). Relatively stable and comparatively high concentrations of IP 25 are observed in zone III (average ...
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... (average 0.3 μg/g d.w) are high in the base of HR7 (zone I as defined by the foraminifera assemblages) (Figs. 5 and 6). In zone II, the terrigenous biomarkers ß-sitosterol (average 0.34 μg/g d.w) and campesterol (average 0.14 μg/g d.w) are relatively low. Out of the 10 samples analysed in zone II, 4 yielded IP 25 values (between 9.5 and 7.75 (Fig. 5). Relatively stable and comparatively high concentrations of IP 25 are observed in zone III (average 1.98 ng/g d.w) and zone IV (average 2.11 ng/g d.w) compared to zone II. The C 37:4 percentage maxima occur before 10 kyr BP (zone I) and decline afterwards (Fig. 4f). Concentrations of ƩC 37 are generally low throughout zone I, followed ...
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... are observed in zone III (average 1.98 ng/g d.w) and zone IV (average 2.11 ng/g d.w) compared to zone II. The C 37:4 percentage maxima occur before 10 kyr BP (zone I) and decline afterwards (Fig. 4f). Concentrations of ƩC 37 are generally low throughout zone I, followed by a gradual increase before reaching their maximum during zone IV (Fig. 4h). (Fig. 5). The concentrations are low throughout zone I and then increase gradually. The calculated P B IP 25 and P D IP 25 indices are high in zone I and vary between 0.19 and 0.93 and 0.17-0.89, respectively (Fig. 5). Both indices show very low values in zone II and relatively low stable records throughout the other ...
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... of ƩC 37 are generally low throughout zone I, followed by a gradual increase before reaching their maximum during zone IV (Fig. 4h). (Fig. 5). The concentrations are low throughout zone I and then increase gradually. The calculated P B IP 25 and P D IP 25 indices are high in zone I and vary between 0.19 and 0.93 and 0.17-0.89, respectively (Fig. 5). Both indices show very low values in zone II and relatively low stable records throughout the other ...
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... low absolute foraminiferal abundances and fluxes coincide with low TOC and Br/Ti (Figs. 4 and 6), altogether indicating that the surface water productivity was low throughout this zone. This is further supported by the relatively low surface productivity proxy records, such as pigments and phytoplankton biomarkers (brassicasterol and dinosterol; Fig. 5). The benthic δ 18 O values are highly variable but are decreasing, which suggest that freshening occurred that was likely due to the occasional freshwater inflow from the inner Hornsund ...
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... base of this zone, between ~11.4 and 11 kyr BP, was characterized by low IP 25 values and low P B IP 25 and P D IP 25 values, suggesting less seasonal sea ice at our core site, probably due to the warm surface water conditions reflected by high U K′ 37 -SSTs (Fig. 5). High values of % C 37:4 between ~11 and 10.2 kyr BP point to a significant influence of cold ArW from the ESC and/or meltwater flux to our study site from the inner Hornsund (Fig. 5). The peak values of Ti/Ca, Fe/Ca, and Sr/Ca and high concentrations of the terrigenous biomarkers campesterol and β-sitosterol could indicate an increase ...
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... P B IP 25 and P D IP 25 values, suggesting less seasonal sea ice at our core site, probably due to the warm surface water conditions reflected by high U K′ 37 -SSTs (Fig. 5). High values of % C 37:4 between ~11 and 10.2 kyr BP point to a significant influence of cold ArW from the ESC and/or meltwater flux to our study site from the inner Hornsund (Fig. 5). The peak values of Ti/Ca, Fe/Ca, and Sr/Ca and high concentrations of the terrigenous biomarkers campesterol and β-sitosterol could indicate an increase in sediment-laden meltwater overflow, most likely from the inner Hornsund (Fig. 6). (Fig. 5) that coincide with the occurrences of S. loeblichi and other glaciomarine indicators ...
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... influence of cold ArW from the ESC and/or meltwater flux to our study site from the inner Hornsund (Fig. 5). The peak values of Ti/Ca, Fe/Ca, and Sr/Ca and high concentrations of the terrigenous biomarkers campesterol and β-sitosterol could indicate an increase in sediment-laden meltwater overflow, most likely from the inner Hornsund (Fig. 6). (Fig. 5) that coincide with the occurrences of S. loeblichi and other glaciomarine indicators (mostly E. clavatum) (Fig. 3) may indicate that the environment was likely affected by sea ice until ~10.2 kyr BP under the influence of cold ArW (see Supplementary Fig. 1; positive correlation between ArW and IP 25 ). U K′ 37 -derived SST records show ...
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... warm AW, as suggested by high abundances of the AW indicators that coincide with a peak in benthic and planktic foraminiferal fluxes and concentrations, which indicate warming of the water column (Fig. 3). Notably, the measured IP 25 concentrations between this period were absent or at least below the LOD, indicating the near absence of sea ice (Fig. 5), also suggested by the absence or very low abundance of S. loeblichi (Fig. 3). This further supports the interpretation that maximum surface warming occurred at that time, which is likely associated with the Holocene Thermal Maximum (HTM). The overall stable distribution of C. reniforme and low abundance of E. clavatum relate to ...
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... distinct reduction in phytoplankton biomarker concentrations between ~10 and 9 kyr BP probably suggests short-term deterioration of the surface water conditions. This coincides with rapidly decreasing IP 25 concentrations and relatively high terrestrial input (Figs. 5 and 6). Therefore, we suggest that the SW Svalbard inner shelf was still affected by considerable sediment-laden meltwater discharge, which may have affected the growth of phytoplankton and ice algae. These surface conditions significantly reduced annual productivity, which is further supported by low foraminiferal fluxes, TOC, pigments, and ...
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... protruded into tidewater glaciers at the Hornsund mouth (Hansbreen), indicating that glacier terminates were terrestrially grounded before ~8 kyr BP (Oer- lemans et al., 2011), and as a result, there was a limited supply of terrestrial materials via icebergs. The reconstructed U K′ 37 -derived SST shows an abrupt decrease at the end of the zone (Fig. 5), which is also indicated by the occurrence of the sea ice indicator species S. loeblichi (Fig. 3), suggesting the presence of sea ice and generally cooler environmental conditions in SW Svalbard. This is further supported by increasing IP 25 values, P B IP 25, and P D IP 25 indices (Fig. ...
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... SST shows an abrupt decrease at the end of the zone (Fig. 5), which is also indicated by the occurrence of the sea ice indicator species S. loeblichi (Fig. 3), suggesting the presence of sea ice and generally cooler environmental conditions in SW Svalbard. This is further supported by increasing IP 25 values, P B IP 25, and P D IP 25 indices (Fig. ...
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... of AW following the later stages of the previous zone (Fig. 4d). Despite the presence of AW during this interval, the sea surface is characterized by sea ice-rich conditions at our study site, as indicated by the continuous occurrence of S. loeblichi from the end of the previous zone and relatively high values of IP 25 , P B IP 25, and P D IP 25 (Fig. 5). Mg/Ca-derived BWT and relatively low (<3‰) and constant benthic δ 18 O records suggest relatively warm and stable bottom water temperatures at our study site. Records from our productivity-indicating proxies point to a gradual increase in surface water productivity during this interval, most likely due to the growth of ice ...
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... site (Figs. 3 and 4). In comparison to the later part of the previous zone, the benthic δ 18 O tends to increase along with an increase in E. clavatum, suggesting relatively cold bottom conditions (Figs. 3 and 4k). This is most likely caused by the continued reduction of AW inflow at our site, which is confirmed by a decrease in Mg/Ca-derived BWT (Fig. ...
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... multiproxy analysis of sediment core OCE2019-HR07-GC reveals that during the earliest Holocene (~11-10.2 kyr BP), even though it was a period of maximum summer insolation (Fig. 5), the SW Svalbard inner shelf water experienced cold conditions, both at the bottom and at the surface. Increased cold and fresher water flux may have promoted recurrent sea ice cover at our core site, as reflected by maximum occurrences of sea ice indicators ( Fig. 5; see also Supplementary Fig. 1, which shows strong negative ...
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... (~11-10.2 kyr BP), even though it was a period of maximum summer insolation (Fig. 5), the SW Svalbard inner shelf water experienced cold conditions, both at the bottom and at the surface. Increased cold and fresher water flux may have promoted recurrent sea ice cover at our core site, as reflected by maximum occurrences of sea ice indicators ( Fig. 5; see also Supplementary Fig. 1, which shows strong negative correlation between U K′ 37 -SSTs and IP 25 ). Similar surface conditions have previously been recorded in the western Barents Sea (core JM09-KA11-GC-GC ( Berben et al., 2014) and JM09-020-GC ( Łącka et al., 2019), Fig. 1), where high %C 37:4 , IP 25, and P B IP 25 together ...
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... The strengthened ESC after ~7 kyr BP ( Sarnthein et al., 2003) may have brought some sea ice-rich cold water from the Barents Sea to our site, which is also shown by the clay mineral composition of the nearby core JM07-015 during that period ( Sternal et al., 2014). This also coincides with a decrease in SSTs and slight increase in the IRD flux (Figs. 5 and 6) in our records, suggesting an overall increase in sea ice rafting and cold surface conditions in the western Svalbard margins, probably due to ice advance ( Hald et al., 2004;Jessen et al., 2010;´ Slubowska-Woldengen et al., 2007). Furthermore, the transition starting ~7 kyr BP was also reported around the western Barents Sea-Svalbard ...
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... in hydrodynamic energy at our study site was most likely due to (1) the expansion of the WSC onto the SW Svalbard shelf and/or (2) the increased vertical circulation in the water column due to excessive heat loss to the atmosphere(e.g., Kuhlbrodt et al., 2007) from AW under open water conditions (reflected in significantly reduced IP 25 ; Fig. 5), which caused strong bottom currents that eroded surface sediments. Another explanation for the strong bottom current could be the formation of dense water as a result of cooling below large icebergs. An increase in IRD content during this interval suggests increased iceberg rafting over the study area, further supporting this ...
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... Lipid biomarkers were analyzed at the Department of Paleoceanography, Institute of Oceanology, Poland, using the procedures described in detail by Krajewska et al. (2023) and spiked with surrogate standards (9-octylheptadecene, 7-hexylnonadecane, 2-nonadecanone, and androstanol) were sonication-extracted with a dichloromethane : methanol (2:1 v/v) mixture (3 ...
... The fraction containing highly branched isoprenoid (IP25) was eluted with a hexane and dichloromethane (1:1 v/v) mixture, whereas the fraction containing alkenones was eluted with dichloromethane. IP25 were analyzed using a gas chromatograph coupled to a quadrupole mass spectrometer detector (GCMS-QP2010 Ultra; Shimadzu) according to the procedure described 185 in Krajewska et al. (2023). The concentrations of IP25 were calculated based on response factors for IP25 and the standards following the procedure described by Belt et al. (2012). ...
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