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Guidebook 19. Field Trip Guidebook Kaolinitic Clays of the Minnesota River Valley and Southwestern Minnesota
Setterholm, Dale R.; Heine, John J. (Minnesota Geological Survey, 1992)
 

Title 
Guidebook 19. Field Trip Guidebook Kaolinitic Clays of the Minnesota River Valley and Southwestern Minnesota

Issue Date
1992

Publisher
Minnesota Geological Survey

Type
Map, Report

Abstract
A thick mantle of chemical weathering products covers crystalline bedrock of Archean and Proterozoic age in much of central and western Minnesota. The mantle has a vertical profile typically composed of progressively more weathered material upward from fresh bedrock to an erosion surface now covered either by strata of Late Cretaceous age or by glacial and postglacial deposits of Quaternary age. In a pioneering study of regional relationships, Parham (1970) showed that most upland areas underlain by crystalline bedrock in western Minnesota have weathering profiles averaging 30 m in thickness, though profiles as great as 60 m thick may be present locally. Weathered materials are considerably thinner on steep side slopes and absent in many places along valleys cut into the bedrock surface. Nonetheless, their widespread occurrence has created considerable commercial interest. Much of our knowledge of the processes responsible for the origin of the weathering profile in southwestern Minnesota was established by S.S. Goldich in a 1936 University of Minnesota doctoral dissertation entitled "A study in rock weathering" (Goldich, 1938). Six samples of saprolite from the Redwood Falls-Morton vicinity in the Minnesota River Valley were compared chemically and mineralogically with fresh Archean gneiss, their probable parent material. Using these data, together with data from elsewhere, Goldich established an alteration sequence in which calcium-rich plagioclase was transformed to clay, followed by the dissolution of the potassium-rich feldspar and other mafic minerals. These observations are embodied in the so-called Goldich stability series, which in one form or another is taught to every beginning student in geology.

Appears in Collection(s)

Other Identifier(s)
issn: 0192-6268

Series/Report Number
Guidebook
19

Description
PREPARED FOR THE 29TH ANNUAL MEETING OF THE CLAY MINERALS SOCIETY AND THE SOIL SCIENCE SOCIETY OF AMERICA MINNEAPOLIS, MINNESOTA, 1992

Suggested Citation
Setterholm, Dale R.; Heine, John J.. (1992). Guidebook 19. Field Trip Guidebook Kaolinitic Clays of the Minnesota River Valley and Southwestern Minnesota. Minnesota Geological Survey. Retrieved from the University of Minnesota Digital Conservancy, http://purl.umn.edu/59140.


Content distributed via the University of Minnesota's Digital Conservancy may be subject to additional license and use restrictions applied by the depositor.