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  • AWI_Paleo; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Siberian River Run-Off; SIRRO  (2)
  • Arctic Ocean; ARK-XXIII/3; AWI_Paleo; Giant box corer; GKG; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; PS72; PS72/410-1  (2)
  • IP25  (2)
Collection
Keywords
Publisher
Language
  • 1
    Publication Date: 2024-02-28
    Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The ultimate demise of the Laurentide Ice Sheet (LIS) and the preceding and succeeding oceanographic changes along the western Labrador Sea offer insights critically important to improve climate predictions of expected future climate warming and further melting of the Greenland ice cap. However, while the final disappearance of the LIS during the Holocene is rather well constrained, the response of sea ice during the resulting meltwater events is not fully understood. Here, we present reconstructions of paleoceanographic changes over the past 9.3 Kyr BP on the northwestern Labrador Shelf, with a special focus on the interaction between the final meltwater event around 8.2 Kyr BP and sea ice and phytoplankton productivity (e.g., IP〈sub〉25〈/sub〉, HBI III (Z), brassicasterol, dinosterol, biogenic opal, total organic carbon). Our records indicate low sea‐ice cover and high phytoplankton productivity on the Labrador Shelf prior to 8.9 Kyr BP, sea‐ice formation was favored by decreased surface salinities due to the meltwater events from Lake Agassiz‐Ojibway and the Hudson Bay Ice Saddle from 8.55 Kyr BP onwards. For the past ca. 7.5 Kyr BP sea ice is mainly transported to the study area by local ocean currents such as the inner Labrador and Baffin Current. Our findings provide new insights into the response of sea ice to increased meltwater discharge as well as shifts in atmospheric and oceanic circulation.〈/p〉
    Description: Key Points: 〈list list-type="bullet"〉 〈list-item〉 〈p xml:lang="en"〉Sea ice on the Labrador Shelf mainly follows the solar insolation and meltwater input from the decaying Laurentide Ice Sheet〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Sea ice increased following the Lake Agassiz outburst and Hudson Bay Ice Saddle Collapse between 8.5 and 8.2 Kyr BP〈/p〉〈/list-item〉 〈list-item〉 〈p xml:lang="en"〉Low sea ice conditions during the Holocene Thermal Maximum were replaced by an increase following the Neoglacial cooling trend〈/p〉〈/list-item〉 〈/list〉 〈/p〉
    Description: Ocean Frontier Institute
    Description: NSERC
    Description: https://doi.org/10.4095/221564
    Description: https://doi.org/10.1594/PANGAEA.949244
    Description: https://doi.org/10.5281/zenodo.8247131
    Description: https://doi.org/10.1594/PANGAEA.949065
    Description: https://doi.org/10.1594/PANGAEA.949056
    Keywords: ddc:551.7 ; sea ice ; Atlantic Ocean ; IP25 ; 8.2 event
    Language: English
    Type: doc-type:article
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  • 2
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    Unknown
    PANGAEA
    In:  Supplement to: Dittmers, Klaus Hauke; Niessen, Frank; Stein, Ruediger (2008): Late Weichselian Fluvial Evolution on the Southern Kara Sea Shelf, North Siberia. Global and Planetary Change, 60(3-4), 327-350, https://doi.org/10.1016/j.gloplacha.2006.12.006
    Publication Date: 2023-05-12
    Description: Glaciations had a profound impact on the global sea-level and particularly on the Arctic environments. One of the key questions related to this topic is, how did the discharge of the Siberian Ob and Yenisei rivers interact with a proximal ice sheet? In order to answer this question high-resolution (1-12 kHz), shallow-penetration seismic profiles were collected on the passive continental margin of the Kara Sea Shelf to study the paleo-drainage pattern of the Ob and Yenisei rivers. Both rivers incised into the recent shelf, leaving filled and unfilled river channels and river canyons/valleys connecting to a complex paleo-drainage network. These channels have been subaerially formed during a regressive phase of the global sea-level during the Last Glacial Maximum. Beyond recent shelf depths of 120 m particle transport is manifested in submarine channel-levee complexes acting as conveyor for fluvial-derived fines. In the NE area, uniform draping sediments are observed. Major morphology determining factors are (1) sea-level fluctuations and (2) LGM ice sheet influence. Most individual channels show geometries typical for meandering rivers and appear to be an order of magnitude larger than recent channel profiles of gauge stations on land. The Yenisei paleo-channels have larger dimensions than the Ob examples and could be originated by additional water release during the melt of LGM Putoran ice masses. Asymmetrical submarine channel-levee complexes with channel depths of 60 m and more developed, in some places bordered by glacially dominated morphology, implying deflection by the LGM ice masses. A total of more than 12,000 km of acoustic profiles reveal no evidence for an ice-dammed lake of greater areal extent postulated by several workers. Furthermore, the existence of the channel-levee complexes is indicative of unhindered sediment flow to the north. Channels situated on the shelf above 120-m water depth exhibit no phases of ponding and or infill during sea-level lowstand. These findings denote the non-existence of an ice sheet on large areas of the Kara Sea shelf.
    Keywords: AWI_Paleo; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Siberian River Run-Off; SIRRO
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 3
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    Unknown
    PANGAEA
    In:  Supplement to: Dittmers, Klaus Hauke; Niessen, Frank; Stein, Ruediger (2008): Acoustic facies on the inner Kara Sea Shelf: implications for late Weichselian to Holocene sediment dynamics. Marine Geology, 254(3-4), 197-215, https://doi.org/10.1016/j.margeo.2008.06.004
    Publication Date: 2023-05-12
    Description: We studied the impact of the last glacial (late Weichselian) sea level cycle on sediment architecture in the inner Kara Sea using high-resolution acoustic sub-bottom profiling. The acoustic lines were ground-truthed with dated sediment cores. Furthermore we refined the location of the eastern LGM ice margin, by new sub bottom profiles. New model results of post-Last Glacial Maximum (LGM) isostatic rebound for this area allow a well-constrained interpretation of acoustic units in terms of sequence stratigraphy. The lowstand (or regressive) system tract sediments are absent but are represented by an unconformity atop of Pleistocene sediments on the shelf and by a major incised dendritic paleo-river network. The subsequent transgressive and highstand system tracts are best preserved in the incised channels and the recent estuaries while only minor sediment accumulation on the adjacent shelf areas is documented. The Kara Sea can be subdivided into three areas: estuaries (A), the shelf (B) and (C) deeper lying areas that accumulated a total of 114 * 10**10 t of Holocene sediments.
    Keywords: AWI_Paleo; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Siberian River Run-Off; SIRRO
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 4
    facet.materialart.
    Unknown
    PANGAEA
    In:  Alfred Wegener Institute - Polarstern core repository
    Publication Date: 2023-06-27
    Keywords: Arctic Ocean; ARK-XXIII/3; AWI_Paleo; Giant box corer; GKG; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; PS72; PS72/410-1
    Type: Dataset
    Format: unknown
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  • 5
    facet.materialart.
    Unknown
    PANGAEA
    In:  Supplement to: Jang, Kwangchul; Han, Yeongcheol; Huh, Youngsook; Nam, Seung-Il; Stein, Ruediger; Mackensen, Andreas; Matthiessen, Jens (2013): Glacial freshwater discharge events recorded by authigenic neodymium isotopes in sediments from the Mendeleev Ridge, western Arctic Ocean. Earth and Planetary Science Letters, 369-370, 148-157, https://doi.org/10.1016/j.epsl.2013.03.018
    Publication Date: 2024-04-27
    Description: The freshwater budget of the Arctic Ocean is a key component governing the deep water formation in the North Atlantic and the global climate system. We analyzed the isotopic composition of neodymium (epsilon-Nd) in authigenic phases of marine sediments on the Mendeleev Ridge in the western Arctic Ocean spanning an estimated time interval from present to about 75 ka BP. This continuous record was used to reconstruct the epsilon-Nd of the polar deep water (PDW) and changes in freshwater sources to the PDW through time. Three deviations in epsilon-Nd from a long term average of -10.2 were identified at estimated 46-51, 35-39 and 13-21 ka BP. The estimated 46-51 ka BP event can be traced to bursting of ice-dammed lakes accompanying the collapse of the Barents-Kara Ice Sheet, which would have released radiogenic Nd to the eastern Arctic Ocean. The cyclonic surface circulation in the eastern Arctic Ocean must have been stronger than at present for the event to be recorded on the Mendeleev Ridge. For the 35-39 and 13-21 ka BP events, it is likely that the Laurentide Ice Sheet (LIS) supplied the unradiogenic freshwater. The configuration of the anticyclonic circulation in the western Arctic was probably similar to today or expanded eastward. Our simple mass balance calculations suggest that large amounts of freshwater were released but due to significant deep water formation within the Arctic Ocean, the effect on the formation of NADW was probably minor.
    Keywords: Arctic Ocean; ARK-XXIII/3; AWI_Paleo; Giant box corer; GKG; Paleoenvironmental Reconstructions from Marine Sediments @ AWI; Polarstern; PS72; PS72/410-1
    Type: Dataset
    Format: application/zip, 4 datasets
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  • 6
    Publication Date: 2021-07-21
    Description: To evaluate the present sea ice changes in a longer‐term perspective, the knowledge of sea ice variability on preindustrial and geological time scales is essential. For the interpretation of proxy reconstructions it is necessary to understand the recent signals of different sea ice proxies from various regions. We present 260 new sediment surface samples collected in the (sub‐)Arctic Oceans that were analyzed for specific sea ice (IP25) and open‐water phytoplankton biomarkers (brassicasterol, dinosterol, and highly branched isoprenoid [HBI] III). This new biomarker data set was combined with 615 previously published biomarker surface samples into a pan‐Arctic database. The resulting pan‐Arctic biomarker and sea ice index (PIP25) database shows a spatial distribution correlating well with the diverse modern sea ice concentrations. We find correlations of PBIP25, PDIP25, and PIIIIP25 with spring and autumn sea ice concentrations. Similar correlations with modern sea ice concentrations are observed in Baffin Bay. However, the correlations of the PIP25 indices with modern sea ice concentrations differ in Fram Strait from those of the (sub‐)Arctic data set, which is likely caused by region‐specific differences in sea ice variability, nutrient availability, and other environmental conditions. The extended (sea ice) biomarker database strengthens the validity of biomarker sea ice reconstructions in different Arctic regions and shows how different sea ice proxies combined may resolve specific seasonal sea ice conditions.
    Description: Key Points: IP25 provides information about modern sea ice cover on a (sub‐)Arctic‐wide scale. All PIP25 indices correlate well with spring and autumn sea ice concentrations on a (sub‐)Arctic‐wide scale. The combination of biomarker data and dinoflagellate cysts may yield an approach to reconstruct sea ice conditions during different seasons.
    Description: EC | Seventh Framework Programme (FP7) http://dx.doi.org/10.13039/100011102
    Description: European Research Council http://dx.doi.org/10.13039/501100000781
    Description: Deutsche Forschungsgemeinschaft (DFG) http://dx.doi.org/10.13039/501100001659
    Keywords: 551 ; biomarker ; IP25 ; PIP25 ; sea ice ; Baffin Bay ; Fram Strait
    Type: article
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