Author

David J. Jung

Publication Date

1988

Document Type

Dissertation/Thesis

First Advisor

Powell, Ross D.

Degree Name

M.S. (Master of Science)

Department

Department of Geology

LCSH

Sedimentation and deposition--Wisconsin||Lithofacies--Wisconsin||Geology, Stratigraphic--Pleistocene||Glaciers--Wisconsin||Geology--Wisconsin

Abstract

Detailed deposystem analysis using lithofacies sequences, lithofacies associations and clast-fabric analyses have been conducted on Wisconsinan glacial and lacustrine successions exposed in coastal bluffs along Lake Michigan in southeast Wisconsin. Results indicate that the Laurentide Ice Sheet had a melting/freezing base where it terminated in a proglacial lake, as a tidewater front. Six different lithofacies types have been identified: (1) unstratified diamicton (sheet Dmu, lens Dmu); (2) stratified diamicton (Dms[r]); (3) interstratified silt and clay (Cld, Zld); (4) unstratified clay (Cud[r]); (5) stratified sand and gravel (G[sub s], S[sub s]); and (6) deformed silt and clay (Md). The oldest sequences preserve proglacial lake sediment of possible Glacial Lake Milwaukee origin. Glacial advance deformed and partially incorporated this sediment subglacially. The overlying subglacial till has previously been identified by others as the Wadsworth Till member of the Oak Creek Formation. Above the till are localized deposits of sediment gravity flows originating from a retreating grounding line. Next, ice-proximal lacustrine rythmites and deeper water muds were deposited along with iceberg-rafted debris. These deposits represent a large- scale glacial retreat previously identified as the Cary- Port Huron retreat. Glacial readvance deposited ice- proximal lacustrine silts and clays which were deformed a overlain by a second subglacial till. Large-scale faults and folds in sediments beneath tills, associated with plastically deformed silts and clays, and subglacial channel deposits indicate that the basal regime of the glacier was melting/freezing. Furthermore, dropstones and debris piles show that the glacier terminated as a grounded temperate glacier front which actively calved and produced icebergs.

Comments

Includes bibliographical references.

Extent

xiii, 336 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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