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Sediment-landform assemblages in southern Michigan; implications for basal processes of the Saginaw Lobe of the Laurentide ice sheet

Alan E. Kehew, John M. Esch and Sita Karki
Sediment-landform assemblages in southern Michigan; implications for basal processes of the Saginaw Lobe of the Laurentide ice sheet (in Quaternary glaciation of the Great Lakes region; process, landforms, sediments, and chronology, Alan E. Kehew (editor) and B. Brandon Curry (editor))
Special Paper - Geological Society of America (January 2018) 530: 115-137

Abstract

Lobes, or ice streams, of the southern Laurentide ice sheet readvanced periodically during their overall retreat after the Last Glacial Maximum in the Great Lakes region. The Saginaw Lobe readvanced around 20 ka to form a prominent moraine, the Sturgis moraine, near the Michigan-Indiana border. Detailed mapping of nineteen 71/2 min quadrangles at a scale of 1:24,000 in and adjacent to Calhoun County, Michigan, supports the interpretation that a large drumlin field behind the moraine was formed at this time, when the basal drainage of the glacier was distributed with high basal pore pressure. During retreat, after moraine construction, the drainage mode switched to a conduit-type system, in which meltwater drained to recessional ice-marginal positions through tunnel valleys. We mapped at least three discontinuous ice-marginal positions on the basis of coarse-grained, subaerial fans beginning at the ends of the tunnel valleys. There is a close association of kames with the tunnel valleys at these locations, suggesting that supraglacial meltwater contributed to the subglacial drainage.Our results support a model in which the drumlins were produced by deformation of the basal diamicton during ice advance prior to the formation of the tunnel valleys during ice retreat. This hypothesis rebuts a previously proposed model for this area in which the drumlins and tunnel valleys, along with boulder gravel deposits, were attributed to formation during a single, catastrophic subglacial sheetflood.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 530
Title: Sediment-landform assemblages in southern Michigan; implications for basal processes of the Saginaw Lobe of the Laurentide ice sheet
Title: Quaternary glaciation of the Great Lakes region; process, landforms, sediments, and chronology
Author(s): Kehew, Alan E.Esch, John M.Karki, Sita
Author(s): Kehew, Alan E.editor
Author(s): Curry, B. Brandoneditor
Affiliation: Western Michigan University, Department of Geosciences, Kalamazoo, MI, United States
Affiliation: Michigan Geological Survey, Department of Geosciences, Kalamazoo, MI, United States
Pages: 115-137
Published: 20180130
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 63
Accession Number: 2024-044964
Categories: Quaternary geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch maps, 1 table, strat. col.
N42°04'00" - N42°23'60", W85°16'60" - W84°42'00"
Secondary Affiliation: Michigan Department of Environmental Quality, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2024, American Geosciences Institute.
Update Code: 2024
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