Chronology and provenance of last-glacial (Peoria) loess in western Iowa and paleoclimatic implications

Quaternary Research
By: , and 



Geologic archives show that the Earth was dustier during the last glacial period. One model suggests that increased gustiness (stronger, more frequent winds) enhanced dustiness. We tested this at Loveland, Iowa, one of the thickest deposits of last-glacial-age (Peoria) loess in the world. Based on K/Rb and Ba/Rb, loess was derived not only from glaciogenic sources of the Missouri River, but also distal loess from non-glacial sources in Nebraska. Optically stimulated luminescence (OSL) ages provide the first detailed chronology of Peoria Loess at Loveland. Deposition began after ~ 27 ka and continued until ~ 17 ka. OSL ages also indicate that mass accumulation rates (MARs) of loess were not constant. MARs were highest and grain size was coarsest during the time of middle Peoria Loess accretion, ~ 23 ka, when ~ 10 m of loess accumulated in no more than ~ 2000 yr and possibly much less. The timing of coarsest grain size and highest MAR, indicating strongest winds, coincides with a summer-insolation minimum at high latitudes in North America and the maximum southward extent of the Laurentide ice sheet. These observations suggest that increased dustiness during the last glacial period was driven largely by enhanced gustiness, forced by a steepened meridional temperature gradient.
Publication type Article
Publication Subtype Journal Article
Title Chronology and provenance of last-glacial (Peoria) loess in western Iowa and paleoclimatic implications
Series title Quaternary Research
DOI 10.1016/j.yqres.2013.06.006
Volume 80
Issue 3
Year Published 2013
Language English
Publisher Academic Press
Publisher location New York, NY
Contributing office(s) Geosciences and Environmental Change Science Center
Description 14 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Quaternary Research
First page 468
Last page 481
Google Analytic Metrics Metrics page
Additional publication details