Simulation of Groundwater Flow and Subglacial Hydrology, Late Pleistocene Lake Michigan Lobe, Laurentide Ice Sheet

2007 ◽  
pp. 63-66 ◽  
Author(s):  
Chris Breemer
Keyword(s):  
Groundwater Flow ◽  
Late Pleistocene ◽  
Lake Michigan ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Lake Michigan Lobe

Absence of Glaciation in Illinois during Marine Isotope Stages 3 through 5

1996 ◽  
Vol 46 (1) ◽  
pp. 19-26 ◽  
Author(s):  
B. Brandon Curry ◽  
Milan J. Pavich
Keyword(s):  
Oxygen Isotope ◽  
Late Stage ◽  
Lake Michigan ◽  
Early Stage ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Argillic Horizon ◽  
Late Wisconsinan ◽  
Lake Michigan Lobe

A10Be inventory and14C ages of material from a core from northernmost Illinois support previous interpretations that this area was ice free from ca. 155,000 to 25,000 yr ago. During much of this period, from about 155,000 to 55,000 yr ago, 10Be accumulated in the argillic horizon of the Sangamon Geosol. Wisconsinan loess, containing inherited 10Be, was deposited above the Sangamon Geosol from ca. 55,000 to 25,000 yr ago and was subsequently buried by late Wisconsinan till deposited by the Lake Michigan Lobe of the Laurentide Ice Sheet. The Sangamonian interglacial stage has been correlated narrowly to marine oxygen isotope substage 5e; our data indicate instead that the Sangamon Geosol developed during late stage 6, all of stages 5 and 4, and early stage 3.

Numerical modeling of subglacial sediment deformation: Implications for the behavior of the Lake Michigan Lobe, Laurentide Ice Sheet

1996 ◽  
Vol 101 (B4) ◽  
pp. 8717-8728 ◽  
Author(s):  
John W. Jenson ◽  
Douglas R. MacAyeal ◽  
Peter U. Clark ◽  
Carlton L. Ho ◽  
Julio C. Vela
Keyword(s):  
Numerical Modeling ◽  
Lake Michigan ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Sediment Deformation ◽  
Lake Michigan Lobe

scholarly journals Modeling the Influence of Till Rheology on the Flow and Profile of the Lake Michigan Lobe, Southern Laurentide Ice Sheet, U.S.A.

1986 ◽  
Vol 32 (111) ◽  
pp. 235-241 ◽  
Author(s):  
James E. Beget
Keyword(s):  
Yield Strength ◽  
Great Plains ◽  
Lake Michigan ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Plastic Behavior ◽  
Mackenzie Delta ◽  
Western Great Plains ◽  
Basal Till ◽  
Lake Michigan Lobe

AbstractThe late Wisconsin Shelbyville till was deposited in southern Illinoisc. 20 000–21 000 year B.P. and records the maximum southern advance of the Lake Michigan lobe of the Laurentide ice sheet. The yield strength calculated for a representative till debris flow found just south of the ice margin is 8 kPa (0.08 bar), and probably approximates yield strength of basal Shelbyville till. An ice-profile model assuming plastic behavior in basal till suggests the southern Lake Michigan lobe may have been unusually thin. Reconstructed Laurentide glacier profiles from the south-west and western Great Plains (South Dakota, Alberta, Minnesota, and Montana), and the MacKenzie Delta, N.W.T., are similar to those inferred for the southern Great Lakes area, and much thinner than those of most modern ice sheets. The Pleistocene Laurentide ice sheet may have been asymmetric: thicker in the east than in the west. Glaciers resting on weak sediments can move both by subglacial sediment deformation (creep) and sliding at the sediment–ice interface. Till rheology is complex; shearing of till by over-riding glaciers would increase porosity and further reduce yield strength.

scholarly journals Deformation of the Batestown till of the Lake Michigan lobe, Laurentide ice sheet

2009 ◽  
Vol 55 (189) ◽  
pp. 131-146 ◽  
Author(s):  
Jason F. Thomason ◽  
Neal R. Iverson
Keyword(s):  
Shear Deformation ◽  
Simple Shear ◽  
Lake Michigan ◽  
Flow Direction ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Ice Flow ◽  
Flow And Sediment Transport ◽  
Basal Till ◽  
Lake Michigan Lobe

AbstractDeep, pervasive shear deformation of the bed to high strains (>100) may have been primarily responsible for flow and sediment transport of the Lake Michigan lobe of the Laurentide ice sheet. To test this hypothesis, we sampled at 0.2 m increments a basal till from one advance of the lobe (Batestown till) along vertical profiles and measured fabrics due to both anisotropy of magnetic susceptibility and sand-grain preferred orientation. Unlike past fabric studies, interpretations were guided by results of laboratory experiments in which this till was deformed in simple shear to high strains. Fabric strengths indicate that more than half of the till sampled has a <5% probability of having been sheared to moderate strains (7–30). Secular changes in fabric azimuth over the thickness of the till, probably due to changing ice-flow direction as the lobe receded, indicate that the bed accreted with time and that the depth of deformation of the bed did not exceed a few decimeters. Orientations of principal magnetic susceptibilities show that the state of strain was commonly complex, deviating from bed-parallel simple shear. Deformation is inferred to have been focused in shallow, temporally variable patches during till deposition from ice.

Numerical modeling of advective transport of saturated deforming sediment beneath the Lake Michigan Lobe, Laurentide Ice Sheet

Geomorphology ◽  
1995 ◽  
Vol 14 (2) ◽  
pp. 157-166 ◽  
Author(s):  
John W. Jenson ◽  
Peter U. Clark ◽  
Douglas R. MacAyeal ◽  
Carleton Ho ◽  
Julio C. Vela
Keyword(s):  
Numerical Modeling ◽  
Lake Michigan ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Advective Transport ◽  
Lake Michigan Lobe

scholarly journals Modeling the Influence of Till Rheology on the Flow and Profile of the Lake Michigan Lobe, Southern Laurentide Ice Sheet, U.S.A.

1986 ◽  
Vol 32 (111) ◽  
pp. 235-241 ◽  
Author(s):  
James E. Beget
Keyword(s):  
Yield Strength ◽  
Great Plains ◽  
Lake Michigan ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Plastic Behavior ◽  
Mackenzie Delta ◽  
Western Great Plains ◽  
Basal Till ◽  
Lake Michigan Lobe

AbstractThe late Wisconsin Shelbyville till was deposited in southern Illinois c. 20 000–21 000 year B.P. and records the maximum southern advance of the Lake Michigan lobe of the Laurentide ice sheet. The yield strength calculated for a representative till debris flow found just south of the ice margin is 8 kPa (0.08 bar), and probably approximates yield strength of basal Shelbyville till. An ice-profile model assuming plastic behavior in basal till suggests the southern Lake Michigan lobe may have been unusually thin. Reconstructed Laurentide glacier profiles from the south-west and western Great Plains (South Dakota, Alberta, Minnesota, and Montana), and the MacKenzie Delta, N.W.T., are similar to those inferred for the southern Great Lakes area, and much thinner than those of most modern ice sheets. The Pleistocene Laurentide ice sheet may have been asymmetric: thicker in the east than in the west. Glaciers resting on weak sediments can move both by subglacial sediment deformation (creep) and sliding at the sediment–ice interface. Till rheology is complex; shearing of till by over-riding glaciers would increase porosity and further reduce yield strength.

Sign in / Sign up

Export Citation Format

Share Document