Skip to Main Content
Skip Nav Destination
GEOREF RECORD

Climatic effects of glacial Lake Agassiz in the Midwestern United States during the last deglaciation

Feng Sheng Hu, Herbert E. Wright, Emi Ito and Kathryn Lease
Climatic effects of glacial Lake Agassiz in the Midwestern United States during the last deglaciation
Geology (Boulder) (March 1997) 25 (3): 207-210

Abstract

Stable isotope and pollen analyses of a sediment core from Deep Lake, Minnesota, provide new information on the climatic effects of glacial Lake Agassiz in Minnesota and insights into the cause of the prominent Picea recurrence during the Younger Dryas in the southern Great Lakes region. Bulk-carbonate delta (super 18) O exhibited large fluctuations between 12.0 and 9.1 ka (dates are in calendar years throughout this paper unless indicated otherwise), probably reflecting the effects of glacial Lake Agassiz superimposed on climatic warming related to large-scale climatic controls. In particular, a 3% decrease in delta (super 18) O 11.2-10.2 ka interrupted the delta (super 18) O enrichment of 1% from 12.0 to 11.2 ka and 3.5% from 10.2 to 9.1 ka. This delta (super 18) O decrease coincided with the expansion of Lake Agassiz. We interpret this decrease as a result of decreased summer temperature and increased precipitation derived from the cold and isotopically light meltwaters of Lake Agassiz. During this delta (super 18) O decline, Pinus pollen continued to increase at the expense of Picea pollen at Deep Lake, as at other Minnesota sites, providing evidence that climatic cooling induced by Lake Agassiz did not cause a reversal to a Picea-dominated vegetation. The absence of such a vegetational response implies that the prominent Picea recurrence during the Younger Dryas in the southern Great Lakes region was not caused solely by climatic cooling due to increased flux of meltwater from Lake Agassiz into the Great Lakes. Instead the Picea recurrence might have been driven primarily by the westward penetration of the Younger Dryas cooling.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 25
Serial Issue: 3
Title: Climatic effects of glacial Lake Agassiz in the Midwestern United States during the last deglaciation
Affiliation: University of Minnesota, Limnological Research Center, Minneapolis, MN, United States
Pages: 207-210
Published: 199703
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 31
Accession Number: 1997-030359
Categories: Quaternary geologyGeochronologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Univ. Minn., Limnol. Res. Cent., Contrib. No. 492
Illustration Description: illus. incl. 1 table, sketch map
N47°40'60" - N47°40'60", W95°22'60" - W95°22'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 199710
Close Modal

or Create an Account

Close Modal
Close Modal