Palaeo-ice-stream onsets : examples from the north-eastern Laurentide Ice Sheet
Reconstructing ice-sheet dynamics from subglacial sediments and landforms. Special issue
Arctic Region ; Baffin Land ; Canada ; Cold area ; Geographical information system ; Glacial features ; Ice sheet ; LANDSAT ; Moraine ; Northwest Territories ; Palaeogeography ; Remote sensing ; Thematic Mapper
The AA. report on observations of glacial landscapes at the head of geomorphologically interpreted palaeo-ice streams, i.e. palaeo-ice-stream onsets. Their work is based on the results of systematic palaeoglaciological mapping of the portion
of north-eastern Canada formerly covered by the Laurentide Ice Sheet. Four different cases are considered and analysed in a geographical information system (GIS) environment with full integration of ancillary topographical and geological data. The AA
. conclude that conditions for the preservation of the onset zones are more likely to be met in the case of relatively small ice streams because these are more rapidly deglaciated.
The aim of this review is to acknowledge the interrelationship between topography and ice sheets in Antarctica that must have necessarily taken place during the last 34 million years. Several attempts have been made using numerical modelling
. In this review, the subglacial topography of Antarctica is inspected with reference to both contemporary ice-flow processes and ice-sheet history. Examples of how landscape evolution have been estimated are discussed, which provides a means by which
the continental scale link between topography and ice-sheet development can be investigated in future.
The Steensby Inlet ice stream in the context of the deglaciation of northern Baffin Island, eastern Arctic Canada
Reconstructing ice-sheet dynamics from subglacial sediments and landforms. Special issue
This paper deals with the glacial history of northern Baffin Island. Its main focus is the glacial bedforms and debris dispersal attributed to the Steensby Inlet flow event, which is interpreted as an ice stream. Antecedent conditions
are illustrated based on recent mapping. The evolution of the ice cover, including its thickness, flow patterns, moraine construction, debris dispersal and inferred ice streams, is presented. The Steensby Inlet flow event and inferred ice stream are then discussed
. Finally, the paper details the devolution of the ice stream into streams of decreasing size and discusses associated corridors of evacuation and lateral sliding scarps.
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
Submarine landforms preserved in bathymetric troughs on the Antarctic continental shelf show that the style of ice stream retreat across the shelf following the last glacial maximum varied between different troughs. Three styles of retreat
are inferred from the geological evidence : rapid, episodic and slow. They indicate that Antarctic palaeo-ice-streams did not respond uniformly to external forcing at the end of the last glacial cycle. Rather, their diachronous retreat reflects the dominance
of local controls in the form of bathymetry and drainage basin size. These data provide important constraints for numerical models that attempt to predict the dynamics of large polar ice sheets.
Geomorphology of the onset area of a paleo-ice stream, Marguerite Bay, Antarctic Peninsula
Reconstructing ice-sheet dynamics from subglacial sediments and landforms. Special issue
Geomorphic features indicate that both glacial and melt-water erosion characterize the onset area of the ancestral Marguerite Ice Stream. The large size of these features indicates that they formed over repeated glacial cycles, most recently during
the Last Glacial Maximum. Ice drainage within the bay and on the inner continental shelf was strongly influenced by tectonic fabric. The glacially sculptured geomorphic features within Marguerite Bay co-exist with anastomosing, radial and relatively
bedforms in the Arctic Ocean - the Chukchi Borderland and the central Lomonosov Ridge. A comparative analysis of glaciogenic morphologies from these areas allows a characterization of the impact of deep-draft ice on the central Arctic Ocean.
Reconstructing ice-sheet dynamics from subglacial sediments and landforms. Special issue
are characterized by 3 seismic facies. A model for the formation of these typical sediment successions is proposed in which valley incision and infill are causally linked. This model is based on the theory of glaciohydraulic supercooling beneath ice-sheet margins