Drift carbonate on the Canadian Shield. II: Carbonate dispersal and ice-flow patterns in northern Manitoba

1988 ◽  
Vol 25 (5) ◽  
pp. 783-787 ◽  
Author(s):  
L. A. Dredge
Keyword(s):  
Acid Rain ◽  
Ice Sheet ◽  
Flow Patterns ◽  
Canadian Shield ◽  
Lake Acidification ◽  
Laurentide Ice Sheet ◽  
Ice Streams ◽  
Dispersal Pattern ◽  
Ice Flow ◽  
Natural Lake

In northern Manitoba, carbonates were glacially dispersed westwards for distances up to 260 km beyond the limit of carbonate bedrock. The dispersal pattern in the surface till reflects the interaction of Keewatin and Hudson – Labrador ice in the region during the Wisconsin glaciation and suggests the presence of ice streams within the Laurentide Ice Sheet. Pre-Wisconsinan tills show different dispersal and ice-flow patterns. In unfrozen terrain, carbonate till sheets on the Shield buffer the effects of natural lake acidification and acid rain; however, their ability to buffer appears to be severely limited in permafrost terrain.

Ice-flow patterns and dispersal of erratics at the southwestern margin of the last Scandinavian Ice Sheet: signature of palaeo-ice streams

Boreas ◽  
2003 ◽  
Vol 32 (1) ◽  
pp. 130-148 ◽  
Author(s):  
KURT H. KJÆR ◽  
MICHAEL HOUMARK-NIELSEN ◽  
NIELS RICHARDT
Keyword(s):  
Ice Sheet ◽  
Flow Patterns ◽  
Ice Streams ◽  
Ice Flow ◽  
Scandinavian Ice Sheet ◽  
Southwestern Margin

scholarly journals Objective Reconstructions of the Late Wisconsinan Laurentide Ice Sheet and the Significance of Deformable Beds

2007 ◽  
Vol 39 (3) ◽  
pp. 229-238 ◽  
Author(s):  
D. A. Fisher ◽  
N. Reeh ◽  
K. Langley
Keyword(s):  
Yield Stress ◽  
Flow Direction ◽  
Three Dimensional ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Ice Streams ◽  
Ice Flow ◽  
Surface Slopes ◽  
Late Wisconsinan

ABSTRACT A three dimensional steady state plastic ice model; the present surface topography (on a 50 km grid); a recent concensus of the Late Wisconsinan maximum margin (PREST, 1984); and a simple map of ice yield stress are used to model the Laurentide Ice Sheet. A multi-domed, asymmetric reconstruction is computed without prior assumptions about flow lines. The effects of possible deforming beds are modelled by using the very low yield stress values suggested by MATHEWS (1974). Because of low yield stress (deforming beds) the model generates thin ice on the Prairies, Great Lakes area and, in one case, over Hudson Bay. Introduction of low yield stress (deformabie) regions also produces low surface slopes and abrupt ice flow direction changes. In certain circumstances large ice streams are generated along the boundaries between normal yield stress (non-deformable beds) and low yield stress ice (deformabie beds). Computer models are discussed in reference to the geologically-based reconstructions of SHILTS (1980) and DYKE ef al. (1982).

scholarly journals Ice Streams of the Laurentide Ice Sheet

2006 ◽  
Vol 58 (2-3) ◽  
pp. 269-280 ◽  
Author(s):  
Monica C.M. Winsborrow ◽  
Chris D. Clark ◽  
Chris R. Stokes
Keyword(s):  
Aerial Photography ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Major Influence ◽  
Ice Streams ◽  
Spatial Organisation ◽  
Ice Flow ◽  
Strength Of Evidence ◽  
Fast Ice ◽  
The Stability

Abstract Ice streams had a major influence on the configuration and the stability of the Laurentide Ice Sheet. Their identification is crucial for an understanding of ice sheet behaviour and their importance is reflected by the recent increase in paleo-ice stream research. This paper provides a synopsis of Laurentide paleo-ice streams, compiled from published sources and our mapping from satellite imagery and aerial photography. In total, 49 hypothesised ice streams are reviewed, and categorised according to the strength of evidence for streaming and knowledge of their extent. A map of Laurentide paleo-ice streams is presented, along with tables documenting the nature of evidence on which streaming behaviour has been invoked. The distribution of ice streams demonstrates the spatial organisation of fast ice flow, and overlapping imprints document major changes in ice flow during retreat. We note that Laurentide paleo-ice streams exhibit a much greater range in size than those currently operating in Antarctica.

scholarly journals Laurentide Ice-Flow Patterns: A Historical Review, and Implications of the Dispersal of Belcher Islands Erratics

2007 ◽  
Vol 44 (2) ◽  
pp. 113-136 ◽  
Author(s):  
Victor K. Prest
Keyword(s):  
Ice Sheet ◽  
Historical Review ◽  
Flow Patterns ◽  
The Arctic ◽  
Laurentide Ice Sheet ◽  
Complex Nature ◽  
Hudson Bay ◽  
Ice Flow ◽  
Flow Models ◽  
The North

ABSTRACTThis paper deals with the evolution of ideas concerning the configuration of flow patterns of the great inland ice sheets east of the Cordillera. The interpretations of overall extent of Laurentide ice have changed little in a century (except in the Arctic) but the manner of growth, centres of outflow, and ice-flow patterns, remain somewhat controversial. Present geological data however, clearly favour the notion of multiple centres of ice flow. The first map of the extent of the North American ice cover was published in 1881. A multi-domed concept of the ice sheet was illustrated in an 1894 sketch-map of radial flow from dispersal areas east and west of Hudson Bay. The first large format glacial map of North America was published in 1913. The binary concept of the ice sheet was in vogue until 1943 when a single centre in Hudson Bay was proposed, based on the westward growth of ice from Labrador/Québec. This Hudson dome concept persisted but was not illustrated until 1977. By this time it was evident from dispersal studies that the single dome concept was not viable. Dispersal studies clearly indicate long-continued westward ice flow from Québec into and across southern Hudson Bay, as well as eastward flow from Keewatin into the northern part of the bay. Computer-type modelling of the Laurentide ice sheet(s) further indicates their complex nature. The distribution of two indicator erratics from the Proterozoicage Belcher Island Fold Belt Group help constrain ice flow models. These erratics have been dispersed widely to the west, southwest and south by the Labrador Sector of more than one Laurentide ice sheet. They are abundant across the Paleozoic terrain of the Hudson-James Bay lowland, but decrease in abundance across the adjoining Archean upland. Similar erratics are common in northern Manitoba in the zone of confluence between Labrador and Keewatin Sector ice. Scattered occurences across the Prairies occur within the realm of south-flowing Keewatin ice. As these erratics are not known, and presumably not present, in Keewatin, they indicate redirection and deposition by Keewatin ice following one or more older advances of Labrador ice. The distribution of indicator erratics thus test our concepts of ice sheet growth.

scholarly journals PISM-LakeCC: Implementing an adaptive proglacial lake boundary into an ice sheet model

2020 ◽  
Author(s):  
Sebastian Hinck ◽  
Evan J. Gowan ◽  
Xu Zhang ◽  
Gerrit Lohmann
Keyword(s):  
Boundary Conditions ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Hudson Bay ◽  
Ice Streams ◽  
Ice Flow ◽  
Glacial Retreat ◽  
Proglacial Lakes ◽  
Lake Model ◽  
Ice Sheet Dynamics

Abstract. Geological records show that vast proglacial lakes existed along the land terminating margins of palaeo ice sheets in Europe and North America. Proglacial lakes impact ice sheet dynamics by imposing marine-like boundary conditions at the ice margin. These lacustrine boundary conditions include changes in the ice sheet’s geometry, stress balance and frontal ablation and therefore affect the entire ice sheet’s mass balance. This interaction, however, has not been rigorously implemented in ice sheet models. In this study, the implementation of an adaptive lake boundary into the Parallel Ice Sheet Model (PISM) is described and applied to the glacial retreat of the Laurentide Ice Sheet (LIS). The results show that the presence of proglacial lakes locally enhances the ice flow. Along the continental ice margin, ice streams and ice lobes can be observed. Lacustrine terminating ice streams cause immense thinning of the ice sheet’s interior and thus play a significant role in the demise of the LIS. Due to the presence of lakes, a process similar to the marine ice sheet instability causes the collapse of the ice saddle over Hudson Bay, which blocked drainage via the Hudson Strait. In control experiments without a lake model, Hudson Bay is still glaciated at the end of the simulation. Future studies should target the development of parametrizations that better describe the glacial-lacustrine interactions.

Glacial dispersal of rock debris in central Gaspésie, Quebec, Canada

1993 ◽  
Vol 30 (8) ◽  
pp. 1697-1707 ◽  
Author(s):  
Rémi Charbonneau ◽  
Peter P. David
Keyword(s):  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Glacial History ◽  
Dispersal Pattern ◽  
Glacial Erosion ◽  
Ice Flow ◽  
Granite Pluton ◽  
Alpine Glacier ◽  
History Of ◽  
Late Wisconsinan

The lithological content of tills in central Gaspésie is evaluated by pebble counting of 231 samples collected in excavation pits and containing 200 pebbles each. The results are used here to establish the pattern of debris dispersal and to infer the glacial history of the area. The dispersal pattern is characterized by well-defined southeasterly (160–170°) and northeasterly (40–60°) trending trains. Half-distance values of glacial transport along the trains range from 5 to 9 km for both directions, suggesting ice flow events of considerable magnitude. The volume of material in the trains represents 1–6 m of glacial erosion of the bedrock. Glacial cirques and short U-shaped valleys, about 100–200 m deep, are incised into the McGerrigle Mountains granite pluton as well as the adjacent metabasalt. The corresponding trains are aligned with these erosional features, indicating that their clast content was derived from those features during an early Alpine Glacier Phase. The southeasterly trending dispersal trains are associated with an invasion of central Gaspésie by the Laurentide Ice Sheet during the Early Wisconsinan, whereas the northeasterly trending trains are associated with a local centre of outflow over Gaspésie during the Late Wisconsinan.

scholarly journals Exploring the use of zircon geochronology as an indicator of Laurentide Ice Sheet till provenance, Indiana, USA

2017 ◽  
Vol 88 (3) ◽  
pp. 525-536 ◽  
Author(s):  
Christine M. Kassab ◽  
Samantha L. Brickles ◽  
Kathy J. Licht ◽  
G. William Monaghan
Keyword(s):  
Lake Michigan ◽  
Ice Sheet ◽  
Canadian Shield ◽  
Laurentide Ice Sheet ◽  
Michigan Basin ◽  
Zircon Geochronology ◽  
Ice Flow ◽  
Zircon Age ◽  
Population Distributions ◽  
Path Models

AbstractA pilot study was designed to evaluate the potential of zircon geochronology as a provenance indicator of till from the Lake Michigan, Saginaw, and Huron-Erie Lobes of the Laurentide Ice Sheet. Based on existing ice flow-path models, we hypothesized that till from each lobe would have different zircon age population distributions because the lobes originated from regions of the Canadian Shield with different bedrock ages. After correcting for zircon fertility, the majority of grains in all till samples are 1600–950 Ma, with ~30 % of ages >2500 Ma. This similarity means that till from the three lobes cannot be clearly differentiated based on their zircon populations. The dominant ages found and the homogeneity of distributions in the till indicates a non-Shield source and, instead, reflect an origin from some combination of underlying till and sedimentary bedrock in the Great Lakes region. Even though the datasets are small, the tills have similarities to zircon distributions in Michigan Basin rocks. This implies that a substantial fraction of zircon in till was not transported long distances from the Canadian Shield. Although zircon ages are not distinct between tills, the method provides a novel application to understand Laurentide Ice Sheet glacial erosion and transport.

scholarly journals Ice-sheet surging and ice-stream formation

1996 ◽  
Vol 23 ◽  
pp. 68-73 ◽  
Author(s):  
A. C. Fowler ◽  
C. Johnson
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Type Equation ◽  
Laurentide Ice Sheet ◽  
Spontaneous Generation ◽  
Ice Streams ◽  
Diffusion Type ◽  
Ice Flow ◽  
Linear Diffusion ◽  
Sliding Dynamics

A simplified model of ice-sheet behaviour is described. It combines the assumptions of rapid ice flow, high viscous activation energy and realistic sediment-based sliding dynamics to form a non-linear diffusion-type equation which can display relaxation oscillations analogous to those of surging glaciers, and which may be relevant to large-scale surges of the Hudson Strait and Cabot Strait ice streams of the Laurentide ice sheet. When the physics of this model is applied to a laterally extensive unidirectional ice flow, such as that in the Siple Coast of Antarctica, an appropriate mechanism may exist for the spontaneous generation of ice streams.

Ice-flow patterns and dispersal of erratics at the southwestern margin of the last Scandinavian Ice Sheet: signature of palaeo-ice streams

Boreas ◽  
2003 ◽  
Vol 32 (1) ◽  
pp. 130-148 ◽  
Author(s):  
KURT H. KJaeR ◽  
MICHAEL HOUMARK-NIELSEN ◽  
NIELS RICHARDT
Keyword(s):  
Ice Sheet ◽  
Flow Patterns ◽  
Ice Streams ◽  
Ice Flow ◽  
Scandinavian Ice Sheet ◽  
Southwestern Margin

scholarly journals Ice-sheet surging and ice-stream formation

1996 ◽  
Vol 23 ◽  
pp. 68-73 ◽  
Author(s):  
A. C. Fowler ◽  
C. Johnson
Keyword(s):  
Large Scale ◽  
Ice Sheet ◽  
Type Equation ◽  
Laurentide Ice Sheet ◽  
Spontaneous Generation ◽  
Ice Streams ◽  
Diffusion Type ◽  
Ice Flow ◽  
Linear Diffusion ◽  
Sliding Dynamics

A simplified model of ice-sheet behaviour is described. It combines the assumptions of rapid ice flow, high viscous activation energy and realistic sediment-based sliding dynamics to form a non-linear diffusion-type equation which can display relaxation oscillations analogous to those of surging glaciers, and which may be relevant to large-scale surges of the Hudson Strait and Cabot Strait ice streams of the Laurentide ice sheet.When the physics of this model is applied to a laterally extensive unidirectional ice flow, such as that in the Siple Coast of Antarctica, an appropriate mechanism may exist for the spontaneous generation of ice streams.

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