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  • 1
    In: Pages (Projekt), PAGES news, Stockholm : PAGES, 1993, 17(2009), 3, Seite 122-123
    In: volume:17
    In: year:2009
    In: number:3
    In: pages:122-123
    Type of Medium: Online Resource
    Pages: Ill., graph. Darst
    Language: English
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  • 2
    Keywords: Hochschulschrift ; Meereskunde ; Klimatologie ; Holozän ; Atlantischer Ozean
    Type of Medium: Online Resource
    Pages: Online-Ressource
    DDC: 550
    Language: English
    Note: Kiel, Univ., Diss., 2011
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  • 3
    In: Boreas, Oxford : Wiley-Blackwell, 1972, 39(2010), 1, Seite 56-68, 0300-9483
    In: volume:39
    In: year:2010
    In: number:1
    In: pages:56-68
    Description / Table of Contents: A 415 cm thick permafrost peat section from the Verkhoyansk Mountains was radiocarbon-dated and studied using palaeobotanical and sedimentological approaches. Accumulation of organic-rich sediment commenced in a former oxbow lake, detached from a Dyanushka River meander during the Younger Dryas stadial, at ~12.5 kyr BP. Pollen data indicate that larch trees, shrub alder and dwarf birch were abundant in the vegetation at that time. Local presence of larch during the Younger Dryas is documented by well-preserved and radiocarbon-dated needles and cones. The early Holocene pollen assemblages reveal high percentages of Artemisia pollen, suggesting the presence of steppe-like communities around the site, possibly in response to a relatively warm and dry climate ~11.4-11.2 kyr BP. Both pollen and plant macrofossil data demonstrate that larch woods were common in the river valley. Remains of charcoal and pollen of Epilobium indicate fire events and mark a hiatus ~11.0-8.7 kyr BP. Changes in peat properties, C31/C27 alkane ratios and radiocarbon dates suggest that two other hiatuses occurred ~8.2-6.9 and ~6.7-0.6 kyr BP. Prior to 0.6 kyr BP, a major fire destroyed the mire surface. The upper 60 cm of the studied section is composed of aeolian sands modified in the uppermost part by the modern soil formation. For the first time, local growth of larch during the Younger Dryas has been verified in the western foreland of the Verkhoyansk Mountains (~170 km south of the Arctic Circle), thus increasing our understanding of the quick reforestation of northern Eurasia by the early Holocene.
    Type of Medium: Article
    Pages: graph. Darst
    ISSN: 0300-9483
    Language: English
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  • 4
    Keywords: Hochschulschrift ; Meereskunde ; Klimatologie ; Holozän ; Atlantischer Ozean
    Type of Medium: Book
    Pages: XVIII, 150 S. , Ill., graph. Darst.
    DDC: 550
    Language: English , German
    Note: Kiel, Univ., Diss., 2011 , Kumulative Dissertation
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  • 5
    Keywords: Hochschulschrift ; Meereskunde ; Klimatologie ; Holozän ; Atlantischer Ozean
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource ( Seiten = 35MB) , Ill., graph. Darst.
    Language: English , German
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  • 6
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    Elsevier
    In:  Marine Micropaleontology, 135 . pp. 45-55.
    Publication Date: 2020-02-06
    Description: Highlights • Planktic foraminifera species show an Early Holocene 14C plateau analogous to the atmospheric 14C plateau at 10.2–9.6 cal ka. • Age-calibrated Early Holocene 14C plateau boundaries provide precise age control in 3 sediment cores on a 900 km long transect. • Differences between planktic foraminiferal and atmospheric 14C ages reveal the 14C reservoir age of local surface waters. • Different planktic species document different 14C reservoir ages characteristic of different surface and subsurface waters. To trace spatial variations in Holocene reservoir ages of surface and subsurface waters we studied narrowly spaced 14C records of planktic foraminifera in three high-sedimentation rate cores from the Nordic Seas, the Barents Sea continental margin and eastern Fram Strait. The two northern cores reveal a distinct Early Holocene 14C plateau in dates on the subsurface dweller Neogloboquadrina pachyderma at 9.3–9.1 14C ka. The plateau was tuned to an atmospheric 14C plateau at 9.0–8.7 14C ka that spans 10.2–9.6 calendar ka. These two plateau boundaries provide robust age control points to estimate short-term changes in sedimentation rate and to correlate paleoceanographic signals over 900 km along the West Spitsbergen Current. The difference between planktic and atmospheric 14C plateau ages suggests local 14C reservoir ages of 370–400 yr. Planktic foraminifera species that inhabit different water masses document different reservoir ages. By comparison, the subpolar N. incompta reveals a reservoir age of 150 yr, probably formed in well-mixed Atlantic-sourced waters during winter. The near-surface dweller Turborotalita quinqueloba shows an age of 290 yr in the Fram Strait, but one of 720 yr at the Barents Sea continental margin. The latter age suggests a calcification within old, meltwater-enriched Arctic surface waters admixed by the East Spitsbergen Current. Likewise, we assign an elevated reservoir age of 760 yr on mixed species at a Norwegian Sea site near 71°N to Preboreal meltwaters that spread from northern Norway far west, also documented by the spatial distribution of a coeval δ13C minimum of N. pachyderma.
    Type: Article , PeerReviewed
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  • 7
    Publication Date: 2020-02-06
    Type: Article , PeerReviewed
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  • 8
    Publication Date: 2017-12-19
    Description: Arctic coastal zones serve as a sensitive filter for terrigenous matter input onto the shelves via river discharge and coastal erosion. This material is further distributed across the Arctic by ocean currents and sea ice. The coastal regions are particularly vulnerable to changes related to recent climate change. We compiled a pan-Arctic review that looks into the changing Holocene sources, transport processes and sinks of terrigenous sediment in the Arctic Ocean. Existing palaeoceanographic studies demonstrate how climate warming and the disappearance of ice sheets during the early Holocene initiated eustatic sea-level rise that greatly modified the physiography of the Arctic Ocean. Sedimentation rates over the shelves and slopes were much greater during periods of rapid sea-level rise in the early and middle Holocene, as a result of the relative distance to the terrestrial sediment sources. However, estimates of suspended sediment delivery through major Arctic rivers do not indicate enhanced delivery during this time, which suggests enhanced rates of coastal erosion. The increased supply of terrigenous material to the outer shelves and deep Arctic Ocean in the early and middle Holocene might serve as analogous to forecast changes in the future Arctic.
    Type: Article , PeerReviewed
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  • 9
    Publication Date: 2019-09-23
    Description: A sediment core from the West Spitsbergen continental margin was studied to reconstruct climate and paleoceanographic variability during the last ~9 ka in the eastern Fram Strait. Our multiproxy evidence suggests that the establishment of the modern oceanographic configuration in the eastern Fram Strait occurred stepwise, in response to the postglacial sea-level rise and the related onset of modern sea-ice production on the shallow Siberian shelves. The late Early and Mid Holocene interval (9 to 5 ka) was generally characterized by relatively unstable conditions. High abundance of the subpolar planktic foraminifer species Turborotalita quinqueloba implies strong intensity of Atlantic Water (AW) inflow with high productivity and/or high AW temperatures, resulting in a strong heat flux to the Arctic. A series of short-lived cooling events (8.2, 6.9. and 6.1 ka) occurred superimposed on the warm late Early and Mid Holocene conditions. Our proxy data imply that simultaneous to the complete postglacial flooding of Arctic shallow shelves and the initiation of modern sea-ice production, strong advance of polar waters initiated modern oceanographic conditions in the eastern Fram Strait at ~5.2 ka. The Late Holocene was marked by the dominance of the polar planktic foraminifer species Neogloboquadrina pachyderma, a significant expansion of sea ice/icebergs, and strong stratification of the water column. Although planktic foraminiferal assemblages as well as sea surface and subsurface temperatures suggest a return of slightly strengthened advection of subsurface Atlantic Water after 3 ka, a relatively stable cold-water layer prevailed at the sea surface and the study site was probably located within the seasonally fluctuating marginal ice zone during the Neoglacial period.
    Type: Article , PeerReviewed
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  • 10
    Publication Date: 2019-09-23
    Description: Sediment core MSM5/5-712 from the West Spitsbergen continental margin has been investigated at high resolution for its seawater-derived neodymium (Nd) and lead (Pb) isotope compositions stored in ferromanganese oxyhydroxide coatings of the sediment particles to reconstruct Holocene changes in the sources and mixing of bottom waters passing the site. The radiogenic isotope data are used in combination with a multitude of proxy indicators for the climatic and oceanographic development of the eastern Fram Strait during the past 8500 years. To calibrate the downcore data, seawater and core top samples from the area were analysed for their radiogenic isotope compositions. Core top leachates reveal relatively high (more radiogenic) Nd isotope compositions between εNd −9.7 and −9.1, which are higher than present-day seawater εNd in eastern Fram Strait (−12.6 to −10.5) and indicate that the seawater values have only been established very recently. The core top data agree well with the downcore signatures within the uppermost 40 cm of the sediment core (εNd −9.1 to −8.8) indicating a reduced inflow of waters from the Nordic Seas, concurrent with cool conditions and a south-eastward shift of the marginal ice zone after ca 2.8 cal ka BP (Late Holocene). High sea-ice abundances in eastern Fram Strait are coeval with the well-known Neoglacial trend in the northern North Atlantic region. In contrast, warmer conditions of the late Early to Mid-Holocene were accompanied by lower (less radiogenic) εNd signatures of the bottom waters indicating an increased admixture from the Nordic Seas (−10.6 to −10.1). A shift to significantly more radiogenic εNd signatures of the detrital material also occurred at 3 cal ka BP and was accompanied by a marked increase in supply of fine-grained ice-rafted material (IRF) from the Arctic Ocean to the core site. The most likely source areas for this radiogenic material are the shallow Arctic shelves, in particular the Kara Sea shelf. The evolution of the Pb isotope compositions of past seawater was dominated by local signatures characterized by high 208, 207, 206Pb/204Pb values during the warm Early and Mid-Holocene periods related to enhanced chemical weathering on Svalbard and high glacial and riverine input derived from young granitic (more radiogenic) material to the West Spitsbergen margin. At 3 cal ka BP both detrital and seawater Pb isotope data changed towards more Kara Sea-like signatures.
    Type: Article , PeerReviewed
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