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Magnetic Susceptibility and Mineral Zonations Controlled by Provenance in Loess along the Illinois and Central Mississippi River Valleys

Quaternary Research

By:
, ,
DOI: 10.1006/qres.1997.1947

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Abstract

Magnetic susceptibility (MS) patterns have proven useful for regional stratigraphic correlations of zones within thick, oxidized Peoria and Roxana Silts along the Illinois and Central Mississippi River valleys for more than 350 km. Variations in MS of C horizon loess are controlled by silt-sized magnetite content and are interpreted to reflect changes in sediment provenance due to fluctuations of the Superior and Lake Michigan glacier lobes and the diversion of the Mississippi River to its present course. Grain size distributions and scanning electron microscopic observations indicate that stratigraphic changes in MS are not significantly influenced by eolian sorting or diagenetic dissolution, respectively. Three compositional zones (lower, middle, and upper) are delineated within Peoria Silt which usually can be traced in the field by MS, the occurrence of clay beds, interstadial soils, and/or subtle color changes. These zones can be correlated with, but are generally of more practical use than, previously studied dolomite zones (McKay, 1977) or clay mineral zones (Frye et al., 1968). However, mineralogical analyses can help to substantiate zone boundaries when in question. MS and compositional zones may indirectly record a climatic signal, primarily through the effect that global cooling has had on ice lobe fluctuations in the Upper Mississippi drainage basin. ?? 1998 University of Washington.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Magnetic Susceptibility and Mineral Zonations Controlled by Provenance in Loess along the Illinois and Central Mississippi River Valleys
Series title:
Quaternary Research
DOI:
10.1006/qres.1997.1947
Volume
49
Issue:
1
Year Published:
1998
Language:
English
Publisher:
Elsevier
Publisher location:
Amsterdam, Netherlands
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Quaternary Research
First page:
24
Last page:
36
Number of Pages:
13