Surficial geology and provenance of glacial deposits of the Saybrook 7.5 minute quadrangle, McLean County, Illinois
Date of Award
Master of Science (MS)
Department of Geography-Geology: Hydrogeology
David H. Malone
The glaciated landscape of much of Illinois is a product of the most recent glacial episode, which is characterized by a series of end moraines composed predominantly of till and deposited by ice flowing into Illinois from the east and northeast around 20,000 years before present time. Two separate projects were completed as part of this thesis to better understand the surficial geology and the source areas of glacial sediment in central Illinois: the creation of a surficial geologic map of the Saybrook 7.5 Minute Quadrangle and a provenance study of granitic clasts from two moraines in the area.
A surficial geologic map was created to characterize and describe Quaternary materials in the Saybrook Quadrangle. Field observations, soil survey data, water well data, and Lidar data were used to construct the map, which was then drafted using Canvas 15. Four lithostratigraphic units are present on the surface of the quadrangle. In stratigraphic order from oldest to youngest are the Tiskilwa Formation, Lemont Formation, Henry Formation, and Cahokia Alluvium.
The provenance study was completed using U-Pb dating of zircon grains in phaneritic quartzofeldspathic cobbles found in tills which compose the Bloomington and Normal Moraines in McLean County in order to better understand the source areas of these glacial deposits. Geochronologic analysis retuned crystallization ages of zircons to be nearly all Archean, with a peak age of 2704 Ma for grains from the Bloomington Moraines and 2714 Ma for grains sampled from the Normal Moraines. Sample clasts were found to be most likely transported from basement rocks in northern Ontario, northeast of Lake Superior.
Rickels, Ellyn S., "Surficial geology and provenance of glacial deposits of the Saybrook 7.5 minute quadrangle, McLean County, Illinois" (2016). Theses and Dissertations. 542.
Imported from ProQuest Rickels_ilstu_0092N_10667.pdf