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  • 2010-2014  (2)
  • 1995-1999  (1)
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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Polar research 18 (1999), S. 0 
    ISSN: 1751-8369
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Geographie , Geologie und Paläontologie
    Notizen: Open sections along Kongsfjodhallet, the north-western coast Kongsfjorden, Svalbard, exhibit marine and glacigenic sediments of Early to Late Plestocene age. Glaciatio, deglaciation and subsequent isostatic rebound caused the formation of three sedimentary successions (A, B and C) that comprise till grading upward into glaciomarine mud, followed by shell-bearing sand, and finally littoral sand and gravel. Six major lithostratigraphic units are recognized. Succession C comprises units 1 and 2, which were deposited during an Early Pleistocene glaciation, followed by deglaciation and subsequent beach progradation. Succession B is divisible into units 3 and 4 and reflects glaciation and eventual emergence as a result of isostatic response. The youngest succesion (A) comprises units 5 and 6, and reflects fiord glaciation followed by a regression during an Early Weichselian glaciation-deglaciation episode. Ice-free conditions may have prevailed untill the Late Weichselian, when a glaciation, confined to the fiord trough, covered parts of Kongsfjordhallet. Deglaciation and isostatic rebound are recorded by Holocene marine terraces up to ca 40 m a. s. l.Marine and glacial events from Kongsfjordhallet are compared with stratigraphic evidence from adjacent regions and it is suggested that the Late Weichselian ice configuration was of a more restricted nature than proposed by previous authors. Glaciers. draining through the larger ford troughs reached the shelf break. while at the same time other parts of western Svalbard could have experienced restricted glaciation.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2016-09-16
    Beschreibung: To better understand Pleistocene climatic changes in the Arctic, integrated palaeoenvironmental and palaeoclimatic signals from a variety of marine and terrestrial geological records as well as geochronologic age control are required, not least for correlation to extra-Arctic records. In this paper we discuss, from an Arctic perspective, methods and correlation tools that are commonly used to date Arctic Pleistocene marine and terrestrial events. We review the state of the art of Arctic geochronology, with focus on factors that affect the possibility and quality of dating, and support this overview by examples of application of modern dating methods to Arctic terrestrial and marine sequences. Event stratigraphy and numerical ages are important tools used in the Arctic to correlate fragmented terrestrial records and to establish regional stratigraphic schemes. Age control is commonly provided by radiocarbon, luminescence or cosmogenic exposure ages. Arctic Ocean deep-sea sediment successions can be correlated over large distances based on geochemical and physical property proxies for sediment composition, patterns in palaeomagnetic records and, increasingly, biostratigraphic data. Many of these proxies reveal cyclical patterns that provide a basis for astronomical tuning. Recent advances in dating technology, calibration and age modelling allow for measuring smaller quantities of material and to more precisely date previously undatable material (i.e. foraminifera for C-14, and single-grain luminescence). However, for much of the Pleistocene there are still limits to the resolution of most dating methods. Consequently improving the accuracy and precision (analytical and geological uncertainty) of dating methods through technological advances and better understanding of processes are important tasks for the future. Another challenge is to better integrate marine and terrestrial records, which could be aided by targeting continental shelf and lake records, exploring proxies that occur in both settings, and by creating joint research networks that promote collaboration between marine and terrestrial geologists and modellers.
    Materialart: Article , PeerReviewed
    Format: text
    Format: other
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Publikationsdatum: 2016-02-02
    Beschreibung: While there are numerous hypotheses concerning glacialeinterglacial environmental and climatic regime shifts in the Arctic Ocean, a holistic view on the Northern Hemisphere’s late Quaternary ice-sheet extent and their impact on ocean and sea-ice dynamics remains to be established. Here we aim to provide a step in this direction by presenting an overview of Arctic Ocean glacial history, based on the present state-of-the-art knowledge gained from field work and chronological studies, and with a specific focus on ice-sheet extent and environmental conditions during the Last Glacial Maximum (LGM). The maximum Quaternary extension of ice sheets is discussed and compared to LGM. We bring together recent results from the circum-Arctic continental margins and the deep central basin; extent of ice sheets and ice streams bordering the Arctic Ocean as well as evidence for ice shelves extending into the central deep basin. Discrepancies between new results and published LGM ice-sheet reconstructions in the high Arctic are highlighted and outstanding questions are identified. Finally, we address the ability to simulate the Arctic Ocean ice sheet complexes and their dynamics, including ice streams and ice shelves, using presently available ice-sheet models. Our review shows that while we are able to firmly reject some of the earlier hypotheses formulated to describe Arctic Ocean glacial conditions, we still lack information from key areas to compile the holistic Arctic Ocean glacial history.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
    Standort Signatur Einschränkungen Verfügbarkeit
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