GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Material
Publisher
Person/Organisation
Language
Years
FID
Subjects(RVK)
  • 1
    Online Resource
    Online Resource
    Ice stream motion facilitated by a shallow-deforming and accreting bed
    Springer Science and Business Media LLC ; 2016
    In:  Nature Communications Vol. 7, No. 1 ( 2016-02-22)
    Details
    In: Nature Communications, Springer Science and Business Media LLC, Vol. 7, No. 1 ( 2016-02-22)
    Abstract: Ice streams drain large portions of ice sheets and play a fundamental role in governing their response to atmospheric and oceanic forcing, with implications for sea-level change. The mechanisms that generate ice stream flow remain elusive. Basal sliding and/or bed deformation have been hypothesized, but ice stream beds are largely inaccessible. Here we present a comprehensive, multi-scale study of the internal structure of mega-scale glacial lineations (MSGLs) formed at the bed of a palaeo ice stream. Analyses were undertaken at macro- and microscales, using multiple techniques including X-ray tomography, thin sections and ground penetrating radar (GPR) acquisitions. Results reveal homogeneity in stratigraphy, kinematics, granulometry and petrography. The consistency of the physical and geological properties demonstrates a continuously accreting, shallow-deforming, bed and invariant basal conditions. This implies that ice stream basal motion on soft sediment beds during MSGL formation is accommodated by plastic deformation, facilitated by continuous sediment supply and an inefficient drainage system.
    Type of Medium: Online Resource
    ISSN: 2041-1723
    URL: Article
    DOI: 10.1038/ncomms10723
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2016
    detail.hit.zdb_id: 2553671-0
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 2
    Online Resource
    Online Resource
    Recent progress on combining geomorphological and geochronological data with ice sheet modelling, demonstrated using the last British–Irish Ice Sheet
    Wiley ; 2021
    In:  Journal of Quaternary Science Vol. 36, No. 5 ( 2021-07), p. 946-960
    Details
    In: Journal of Quaternary Science, Wiley, Vol. 36, No. 5 ( 2021-07), p. 946-960
    Abstract: Palaeo‐ice sheets are important analogues for understanding contemporary ice sheets, offering a record of ice sheet behaviour that spans millennia. There are two main approaches to reconstructing palaeo‐ice sheets. Empirical reconstructions use the available glacial geological and chronological evidence to estimate ice sheet extent and dynamics but lack direct consideration of ice physics. In contrast, numerically modelled simulations implement ice physics, but often lack direct quantitative comparison with empirical evidence. Despite being long identified as a fruitful scientific endeavour, few ice sheet reconstructions attempt to reconcile the empirical and model‐based approaches. To achieve this goal, model‐data comparison procedures are required. Here, we compare three numerically modelled simulations of the former British–Irish Ice Sheet with the following lines of evidence: (a) position and shape of former margin positions, recorded by moraines; (b) former ice‐flow direction and flow‐switching, recorded by flowsets of subglacial bedforms; and (c) the timing of ice‐free conditions, recorded by geochronological data. These model–data comparisons provide a useful framework for quantifying the degree of fit between numerical model simulations and empirical constraints. Such tools are vital for reconciling numerical modelling and empirical evidence, the combination of which will lead to more robust palaeo‐ice sheet reconstructions with greater explicative and ultimately predictive power.
    Type of Medium: Online Resource
    ISSN: 0267-8179 , 1099-1417
    URL: Issue
    URL: Article
    DOI: 10.1002/jqs.v36.5
    DOI: 10.1002/jqs.3098
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2031875-3
    SSG: 13
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Corrigendum to “The composition and internal structure of drumlins: complexity, commonality, and implications for a unifying theory of their formation” [Earth Sci. Rev. 107/3–4 (2011) pp. 398–422]
    Elsevier BV ; 2011
    In:  Earth-Science Reviews Vol. 109, No. 1-2 ( 2011-11), p. 61-
    Details
    In: Earth-Science Reviews, Elsevier BV, Vol. 109, No. 1-2 ( 2011-11), p. 61-
    Type of Medium: Online Resource
    ISSN: 0012-8252
    URL: Article
    DOI: 10.1016/j.earscirev.2011.09.002
    RVK:
    RA 1000
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2011
    detail.hit.zdb_id: 1792-9
    detail.hit.zdb_id: 2012642-6
    SSG: 13
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 4
    Online Resource
    Online Resource
    Geomorphological criteria for identifying Pleistocene ice streams
    International Glaciological Society ; 1999
    In:  Annals of Glaciology Vol. 28 ( 1999), p. 67-74
    Details
    In: Annals of Glaciology, International Glaciological Society, Vol. 28 ( 1999), p. 67-74
    Abstract: Ice streams are critical regulatory mechanisms in contemporary ice sheets. It has been inferred that they also had a significant effect on the dynamics of former ice sheets. Subsequently, many people have invoked their widespread occurrence from a variety of formerly glaciated areas. Hypothesised locations, however, have often outweighed meaningful evidence. This paper addresses the problem, using the characteristics of contemporary ice streams as a basis for their identification from former ice-sheet beds. A convergence of knowledge gained from contemporary ice-stream research, coupled with theories of glacial geomorphology, allows several geomorphological criteria to be identified as suggestive signatures of ice-stream activity. It is envisaged that the geomorphological criteria developed here will introduce a more objective approach to the study of former ice streams. The criteria are used to construct conceptual land-system models of the beds of former ice streams, and it is hoped such models can provide an observational template upon which hypotheses of former ice streams can be better based.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    URL: Article
    DOI: 10.3189/172756499781821625
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 1999
    detail.hit.zdb_id: 2122400-6
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 5
    Online Resource
    Online Resource
    Geomorphological Map of Ribbed Moraines on the Dubawnt Lake Palaeo-Ice Stream Bed: A Signature of Ice Stream Shut-down?
    Informa UK Limited ; 2006
    In:  Journal of Maps Vol. 2, No. 1 ( 2006-01), p. 1-9
    Details
    In: Journal of Maps, Informa UK Limited, Vol. 2, No. 1 ( 2006-01), p. 1-9
    Type of Medium: Online Resource
    ISSN: 1744-5647
    URL: Article
    DOI: 10.4113/jom.2006.43
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2006
    detail.hit.zdb_id: 2176732-4
    SSG: 14,1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 6
    Online Resource
    Online Resource
    A groove-ploughing theory for the production of mega-scale glacial lineations, and implications for ice-stream mechanics
    International Glaciological Society ; 2003
    In:  Journal of Glaciology Vol. 49, No. 165 ( 2003), p. 240-256
    Details
    In: Journal of Glaciology, International Glaciological Society, Vol. 49, No. 165 ( 2003), p. 240-256
    Abstract: Mega-scale glacial lineations (MSGLs) are longitudinally aligned corrugations (ridge–groove structures 6–100 km long) in sediment produced subglacially. They are indicators of fast flow and a common signature of ice-stream beds. We develop a qualitative theory that accounts for their formation, and use numerical modelling, and observations of ice-stream beds to provide supporting evidence. Ice in contact with a rough (scale of 10–10 3 m) bedrock surface will mimic the form of the bed. Because of flow acceleration and convergence in ice-stream onset zones, the ice-base roughness elements experience transverse strain, transforming them from irregular bumps into longitudinally aligned keels of ice protruding downwards. Where such keels slide across a soft sedimentary bed, they plough through the sediments, carving elongate grooves, and deforming material up into intervening ridges. This explains MSGLs and has important implications for ice-stream mechanics. Groove ploughing provides the means to acquire new lubricating sediment and to transport large volumes of it downstream. Keels may provide basal drag in the force budget of ice streams, thereby playing a role in flow regulation and stability. We speculate that groove ploughing permits significant ice-stream widening, thus facilitating high-magnitude ice discharge.
    Type of Medium: Online Resource
    ISSN: 0022-1430 , 1727-5652
    URL: Article
    DOI: 10.3189/172756503781830719
    Language: English
    Publisher: International Glaciological Society
    Publication Date: 2003
    detail.hit.zdb_id: 2140541-4
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 7
    Online Resource
    Online Resource
    Ice Streams of the Laurentide Ice Sheet
    Consortium Erudit ; 2006
    In:  Géographie physique et Quaternaire Vol. 58, No. 2-3 ( 2006-07-18), p. 269-280
    Details
    In: Géographie physique et Quaternaire, Consortium Erudit, Vol. 58, No. 2-3 ( 2006-07-18), p. 269-280
    Abstract: Les courants glaciaires ont eu une influence déterminante sur la configuration et la stabilité de l’Inlandsis Laurentidien. Leur identification est cruciale pour la compréhension du comportement de la calotte glaciaire et l’intensification récente de la recherche sur les courants paléoglaciaires témoigne de leur importance. Dans cet article, nous présentons une vue d’ensemble des courants paléoglaciaires de l’Inlandsis Laurentidien, compilée à partir de la revue des sources publiées et de notre cartographie établie à l’aide d’imagerie satellite et de photographies aériennes. En tout, nous avons étudié 49 hypothèses de courants glaciaires. Nous les avons classées selon l’importance du témoignage de leur écoulement et la connaissance que nous avons de leur extension. Nous proposons une carte des courants paléoglaciaires laurentidiens ainsi que des tableaux décrivant la nature de la preuve permettant d’établir le comportement de l’écoulement. La répartition des courants glaciaires montre l’organisation spatiale d’un écoulement glaciaire rapide et le chevauchement des empreintes traduit les changements de l’écoulement durant son retrait. Nous notons que la taille des courants paléoglaciaires laurentidiens est plus importante que celle des courants glaciaires actuels de l’Antarctique.
    Type of Medium: Online Resource
    ISSN: 1492-143X , 0705-7199
    URL: Article
    DOI: 10.7202/013142ar
    Language: English
    Publisher: Consortium Erudit
    Publication Date: 2006
    detail.hit.zdb_id: 2035245-1
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 8
    Online Resource
    Online Resource
    The Dubawnt Lake palaeo-ice stream: evidence for dynamic ice sheet behaviour on the Canadian Shield and insights regarding the controls on ice-stream location and vigour
    Wiley ; 2003
    In:  Boreas Vol. 32, No. 1 ( 2003-03), p. 263-279
    Details
    In: Boreas, Wiley, Vol. 32, No. 1 ( 2003-03), p. 263-279
    Type of Medium: Online Resource
    ISSN: 0300-9483
    URL: Article
    DOI: 10.1111/j.1502-3885.2003.tb01442.x
    Language: English
    Publisher: Wiley
    Publication Date: 2003
    detail.hit.zdb_id: 2028632-6
    detail.hit.zdb_id: 185110-X
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 9
    Online Resource
    Online Resource
    Ice stream shear margin moraines
    Wiley ; 2002
    In:  Earth Surface Processes and Landforms Vol. 27, No. 5 ( 2002-05), p. 547-558
    Details
    In: Earth Surface Processes and Landforms, Wiley, Vol. 27, No. 5 ( 2002-05), p. 547-558
    Abstract: The distribution and pattern of subglacial bedforms provides valuable insights into the configuration and behaviour of former ice sheets and recent work has begun to address the landform assemblages of palaeo‐ice streams. In this paper, we focus on subglacially formed ice stream shear margin moraines; these landforms are thought to form in the shear zone between fast‐flowing stream‐ice and slow‐moving sheet‐ice. Using satellite imagery and aerial photographs, we identify four ice stream shear margin moraines associated with the former M'Clintock Channel Palaeo‐Ice Stream, Victoria Island, Arctic Canada. The moraines range in length from 11 to 22 km, maintain fairly constant widths of around 500 m, and range in height from 10 to 50 m above the surrounding terrain. They are composed of carbonate drift of a similar composition as the ice stream bedforms and have been laid down irrespective of local and regional topography. Two of the moraines display a lateral offset and are thought to reflect minor migrations of the ice stream margin. We explore their possible mode of formation and suggest that they occur when erosion at the ice stream margin provides a surplus of sediment which is ‘smeared out’ in the downstream direction. The identification of other palaeo‐ice stream shear margin moraines has probably been hampered by their interrupted continuity which can only be appreciated at the large scale. It is hoped that the descriptions presented in this paper will help to identify these landforms and increased detection of palaeo‐ice streams will reveal other ice stream shear margin moraines. Copyright © 2002 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 0197-9337 , 1096-9837
    URL: Issue
    URL: Article
    DOI: 10.1002/esp.v27:5
    DOI: 10.1002/esp.326
    Language: English
    Publisher: Wiley
    Publication Date: 2002
    detail.hit.zdb_id: 1479188-2
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 10
    Online Resource
    Online Resource
    Superimposition of ribbed moraines on a palaeo‐ice‐stream bed: implications for ice stream dynamics and shutdown
    Wiley ; 2008
    In:  Earth Surface Processes and Landforms Vol. 33, No. 4 ( 2008-04-15), p. 593-609
    Details
    In: Earth Surface Processes and Landforms, Wiley, Vol. 33, No. 4 ( 2008-04-15), p. 593-609
    Abstract: The sediments and landforms preserved on palaeo‐ice‐stream beds can provide important information about their subglacial conditions and flow mechanisms, and the processes accompanying their shutdown. In this paper, detailed observations of an intriguing subglacial landform assemblage of ribbed moraines superimposed on glacial lineations on the Dubawnt Lake Ice Stream bed (north‐west Canadian Shield) are presented, including their morphometry, internal structure (from ground penetrating radar (GPR) surveys and from glaciogeological analysis) and sedimentological characteristics (from sediment architecture and lithofacies analysis). The observations suggest an abrupt change in ice dynamics that correlates with two phases of glacial landform development. This hypothesis is based on evidence from a deformed lodgement till, which subsequently underwent brittle deformation and developed prominent thrust (shear) structures and tension fractures. Tension fractures are observed in a sediment exposure and thrust structures are observed in GPR surveys, where they occur most prominently in the ribbed moraine ridge crests. The presence of the fractures, and their association with a population of clasts in the till that are orientated with their a‐ axes transverse to the inferred ice flow direction, suggests a compressional flow regime. It is therefore inferred that the glacial lineations were formed under an extensional flow regime during ice stream activity, but that at some point patches of till under the ice stream stiffened through dewatering. The subsequent increase in basal shear stress resulted in compressional flow and the development of subglacial thrusting and the building of ribbed moraines. We therefore suggest that ribbed moraines may form in areas of compressional flow under ice streams, i.e. sticky spots, and/or at the transition between slow and fast ice flow along parts of an ice stream. The general absence of ribbed moraines on most other palaeo‐ice‐stream beds suggests that either these ice streams continued operating during deglaciation or processes other than the development of localized compressional flow (sticky spots) led to their shutdown (e.g. ice depletion). Copyright © 2008 John Wiley & Sons, Ltd.
    Type of Medium: Online Resource
    ISSN: 0197-9337 , 1096-9837
    URL: Issue
    URL: Article
    DOI: 10.1002/esp.v33:4
    DOI: 10.1002/esp.1671
    Language: English
    Publisher: Wiley
    Publication Date: 2008
    detail.hit.zdb_id: 1479188-2
    SSG: 14
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...