Provenance Analysis Of Granite Cobbles In The Tiskilwa Till Using U-Pb Geochronology

• Main Author: Meister, Paul Antone
• Format: Text
• Language: unknown
• Published: ISU ReD: Research and eData 2016
• Subjects: Geochronology; Glacial Till; U-Pb; Zircon; Hydrology; Hudson Bay; Hudson; Peoria
• Online Access: https://ir.library.illinoisstate.edu/etd/624; https://ir.library.illinoisstate.edu/cgi/viewcontent.cgi?article=1624&context=etd

U-Pb isotopic ages were determined for zircons extracted from granitic and related rocks in the Tiskilwa till to determine their origin. Crystalline cobbles (n = 750) were collected at localities from each of the four of the sub-lobes of the terminal Wisconsin moraines. Two sites were chosen from the Decatur, Peoria, and Princeton sub-lobes with one sample taken from the Harvard sub-lobe. Each sample was then individually processed, the zircons handpicked (n = 301), and geochronology conducted using LA-MC-ICPMS at the University of Arizona Laserchron Center. A Kolmogorov-Smirnov (K-S) statistical analysis show that all samples have identical zircon age spectra with the populations being dominated by Archean age (>2.5 Ga) grains and peak age being 2.7 Ga. The dominance of Archean grains indicate a source located in the Superior Province, with the Hudson Bay Terrane (3.36 – 2.69 Ga) being the most likely source area for the granite clasts. In successfully utilizing granite clasts to determine provenance, this study could provide further insight into glacial transport systems.