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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 35 (1988), S. 0 
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: A thick late Pleistocene sequence, comprising multiple beds of massive diamict facies resting on outwash gravels, occurs along the Bow River, near Banff, Alberta. Diamicts have a simple sheet-like geometry which dip downvalley at between 5° and 10°, with largely conformable bedding contacts. The sediments are strongly bimodal in texture, consisting of clasts supported by a silty sand matrix. Prolate clasts show a weak a-axis alignment parallel and transverse to the trend of the Bow Valley with a weak imbrication. Clasts of soft sediment are common. The diamict sequence has a maximum thickness of 30 m, infills the valley floor over an area of approximately 12 km2 and buries a channelled topography cut on the surface of underlying outwash gravels. Abandoned braided channels, veneered by windblown sand containing volcanic tephra dated at 6600 yr bp, occur on the infill surface.Diamict facies were emplaced as subaerial debris flows derived by the mixing and remobilization of large volumes of outwash and glaciolacustrine sediment. Orientation data from clasts and a few basal grooves indicate that debris was derived upvalley and from adjacent valleyside slopes. A major episode of debris flow sedimentation may have been triggered by the abrupt drainage of lakes in tributary valleys as the Bow Valley glacier retreated. Downslope resedimentation of large volumes of sediment resulted in braided river aggradation downstream along the Bow River and can be dated to between 12 000 and 10 000 yr bp. Similar conditions probably occurred during deglaciation throughout the Canadian Cordillera and many other alpine areas, where poorly-sorted late glacial debris-flow facies have been mistaken for tills deposited directly by glaciers. The late glacial setting identified in this paper provides a basis of comparison with ancient continental glacial facies preserved in areas of active tectonism and high relief.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 37 (1990), S. 0 
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: A late Pleistocene morainal bank is sited in a depocentre to the lee of a major rock ridge, near Greystones, in the western Irish Sea Basin. During deglaciation the ridge provided a pinning point during tidewater wastage northwards. Sedimentation patterns and palaeocurrent data show morainal bank growth by discharge from a single basal efflux located to the east or south-east of the ridge during ice marginal re-equilibration.The four lithofacies associations which are recognized from the western part of the formerly more extensive apron are related largely to variable jet and plume sedimentation. At the base of the 1.6 km long exposure, Lithofacies association 1 (massive mud, muddy diamict and laminated mud) was deposited from turbid plumes, variable ice rafting and traction current activity. Lenticular units of gravels within this mud bank record high energy pulses and sediment fluxes from the efflux jet. Lithofacies association 2 (sands, laminated muds and muddy diamict) is discontinuous and occurs within basins along a marked erosion surface cut in Lithofacies association 1. It is associated with a decrease in jet strength, traction currents and suspension sedimentation. Lithofacies association 3 is a tabular body of interbedded diamicts and gravels which is present along the entire section. It documents the decay phase of re-equilibration as the ice margin disintegrated catastrophically and released large volumes of heterogeneous sediment which was resedimented by quasicontinuous mass flow. Lithofacies association 4 consists of stratified and massive gravels within distributary channels cut into underlying facies and represents the last phase of meltwater activity.Sediment geometries, particularly sedimentary contrasts representing erosion surfaces at a variety of scales and abrupt textural contrasts are attributed to jet switching. Lithofacies association 1 (60%) and Lithofacies association 3 (30%) are the dominant facies. In favourable topographic settings this stratigraphic couplet is a signature for re-equilibrated ice margins in isostatically depressed basins dominated by tidewater fronts, rapid ice flux and high relative sea level.Morainal banks document rapid environmental change and in the Irish Sea Basin they form part of a deglacial event stratigraphy related to unstable tidewater margins and high relative sea level. Deglaciation was therefore controlled primarily by high relative sea level rather than climatic forcing. Facies variations should therefore not be used for stratigraphic correlations in place of direct stratigraphy. This type of situation may be more common than hitherto realized in Late Pleistocene, mid-latitude shelves where most of the preserved stratigraphy is characterized by complex, interbedded sequences formed when isostatic depression exceeded sea-level fall.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 36 (1989), S. 0 
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Coastal exposures of Late Pleistocene sediments deposited after 19 000 yr BP near Dublin, Ireland, provide a window into the infill of a subglacially-cut tunnel valley. Exposures close to the steeply dipping bedrock wall of the valley show boulder gravels within multi-storey U-shaped channels cut and filled by subglacial meltwaters driven by a high hydrostatic head. Gravels are truncated by poorly sorted ice-proximal glaciomarine sediments that record the pumping of large volumes of subglacial debris along the tunnel valley to a tidewater ice sheet margin. The sedimentary succession is dominated by sediment gravity flow facies comprising interbedded diamict and massive, poorly sorted gravel facies interpreted as subaqueous debris flow deposits. Gravel beds show local inverse and normal coarse-tail graded facies recording the restricted development of turbulent flow. Sediment gravity flow deposits fill broad (〈2 km) shallow (10 m) and overlapping channels. Penetrative deformation structures (e.g. dykes) are common at the base of channels.The same subglacially-eroded topography and glaciomarine infill stratigraphy can be identified on high resolution seismic profiles across nearly 600 km2 of the western Irish Sea. Tunnel valleys are argued to have been exposed to glaciomarine processes by the rapid retreat of a calving tidewater ice sheet margin in response to marine flooding caused by glacio-isostatic downwarping below the last British Ice Sheet. The facies associations described in this paper comprise an event stratigraphy that may be found on other glaciated continental shelves.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Late Pleistocene morainic sequences around Dundalk Bay, eastern Ireland, were deposited in a variety of shallow, glaciomarine environments at the margins of a grounded ice lobe. The deposits are essentially ice-proximal delta-fan and -apron sequences and are divided into two lithofacies associations. Lithofacies association 1 occurs as a series of morainal banks formed at the southern margin of the ice lobe in a body of water open to influences from the Irish Sea. The morainal banks consist mainly of diamictic muds deposited from turbid plumes and by ice-rafting with minor occurrences of turbidites, cross-bedded gravels (subaqueous outwash) and massive boulder gravels (high-density debris flows). Lithofacies association 2 was deposited in a narrow arm of the sea at the north-eastern margin of the ice lobe. The deposits consist mainly of a series of coalescing, ice-proximal Gilbert-type fan deltas which are interbedded distally with tabular and lens-shaped subaqueous deposits. The latter are mainly ice-rafted diamictons, debris-flow deposits and subaqueous sands and gravels. Both lithofacies associations are draped by diamictons formed by a combination of rain-out, debris flow and traction-current activity. At a few localities the upper parts of the sequence have been sheared by minor oscillations of the ice sheet margin.These sequences form part of an extensive belt of glaciomarine deposits which border the drumlin swarms of east-central Ireland. Lithostratigraphic variability is partially related to the arrival of large volumes of debris at the ice lobe margin when the main lowland ice sheet surged during drumlin formation. Complex depositional continua of this type lack any major erosional breaks and should not be used either as climatic proxies or for stratigraphic correlations.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Strong early Holocene crustal uplift over the Spitsbergen archipelago reflects disappearance of an ice mass centred just north-east of the archipelago and which decayed rapidly just after 10,000 BP after a maximum extension between 12,600 and 10,000 BP. From the lithofacies distributions associated ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 392 (1998), S. 373-377 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Millennial-scale variability in the flux of ice-rafted detritus to North Atlantic sediments during the last glacial period has been interpreted to reflect a climate-forced increase in the discharge of icebergs from ice-sheet margins surrounding the northern North Atlantic Ocean. But the ...
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0147-619X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Linguistics and Education 5 (1993), S. 187-194 
    ISSN: 0898-5898
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Linguistics and Literary Studies , Education
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Organometallic Chemistry 384 (1990), S. 217-221 
    ISSN: 0022-328X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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