Timing, provenance, and implications of two MIS 3 advances of the Laurentide Ice Sheet into the Upper Mississippi River Basin, USA

QUATERNARY SCIENCE REVIEWS

卷:261

Article

Kerr, Phillip J.¹  Tassier-Surine, Stephanie A.¹  Kilgore, Susan M.²  Bettis, E. Arthur³  Dorale, Jeffrey A.³  Cramer, Bradley D.³ 

[1] Univ Iowa, Iowa Geol Survey, Iowa City, IA 52242 USA

[2] Adelphi Univ, Environm Studies & Sci, Garden City, NY 11530 USA

[3] Univ Iowa, Dept Earth & Environm Sci, Iowa City, IA 52242 USA

关键词: North American Glaciation;    MIS 3;    Laurentide ice sheet;    Iowa;    Roxana silt;    Keewatin;    Middle Wisconsin;    Quaternary;    Des moines lobe;    Marine isotope stage 3;   

DOI  :  10.1016/j.quascirev.2021.106926

来源: Elsevier

【 摘 要 】

Evidence for a glacial advance into the Upper Mississippi River Basin between Marine Isotope Stage (MIS) 2 and MIS 6 has been debated for over a century. New sedimentological and chronological data provide evidence for two advances of the Laurentide Ice Sheet (LIS) into Iowa during MIS 3 to the east and west of the local glacial maximum margin. The lithology of the MIS 3 till is similar to the MIS 2 Des Moines Lobe till, which suggests both tills were sourced from the Keewatin Dome. A synthesis of new and previously collected radiocarbon ages indicate the two advances reached their terminus near 42 degrees N around 42 ka and 30 ka. A comparison of this record with published loess chronology and provenance studies suggests that these advances were likely a glacial source for the Mississippi Valley Roxana Silt and the Pisgah Formation loess in the Missouri River Valley. The apparent discrepancy between the basal ages of the Roxana and Pisgah loesses may be due to the timing of Des Moines Lobe entering the Mississippi River watershed before the Missouri River watershed. The results of this study demonstrate that the LIS advanced much farther south during MIS 3 than previously recognized, which has significant implications for ice sheet and paleoclimate modeling. Published by Elsevier Ltd.

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