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Last glacial maximum climate inferences from cosmogenic dating and glacier modeling of the western Uinta ice field, Uinta Mountains, Utah

Published online by Cambridge University Press:  20 January 2017

Kurt A. Refsnider*
Affiliation:
Department of Geology and Geophysics, University of Wisconsin, 1215 W Dayton St., Madison, WI 53706, USA
Benjamin J.C. Laabs
Affiliation:
Department of Geological Sciences, SUNY Geneseo, 1 College Circle, Geneseo, NY 14454, USA
Mitchell A. Plummer
Affiliation:
Idaho National Laboratory, Idaho Falls, ID 83415-2107, USA
David M. Mickelson
Affiliation:
Department of Geology and Geophysics, University of Wisconsin, 1215 W Dayton St., Madison, WI 53706, USA
Bradley S. Singer
Affiliation:
Department of Geology and Geophysics, University of Wisconsin, 1215 W Dayton St., Madison, WI 53706, USA
Marc W. Caffee
Affiliation:
Department of Physics, Purdue University, 1296 Physics Building, W. Lafayette, IN 47907, USA
*
*Corresponding author. Current address: Institute of Arctic and Alpine Research, 1560 30th St. 450 UCB, Boulder, CO 80303, USA.E-mail address: kurt.refsnider@colorado.edu (K.A. Refsnider).

Abstract

During the last glacial maximum (LGM), the western Uinta Mountains of northeastern Utah were occupied by the Western Uinta Ice Field. Cosmogenic10Be surface-exposure ages from the terminal moraine in the North Fork Provo Valley and paired26Al and10Be ages from striated bedrock at Bald Mountain Pass set limits on the timing of the local LGM. Moraine boulder ages suggest that ice reached its maximum extent by 17.4±0.5 ka (± 2σ).10Be and26Al measurements on striated bedrock from Bald Mountain Pass, situated near the former center of the ice field, yield a mean26Al/10Be ratio of 5.7±0.8 and a mean exposure age of 14.0±0.5 ka, which places a minimum-limiting age on when the ice field melted completely. We also applied a mass/energy-balance and ice-flow model to investigate the LGM climate of the western Uinta Mountains. Results suggest that temperatures were likely 5 to 7°C cooler than present and precipitation was 2 to 3.5 times greater than modern, and the western-most glaciers in the range generally received more precipitation when expanding to their maximum extent than glaciers farther east. This scenario is consistent with the hypothesis that precipitation in the western Uintas was enhanced by pluvial Lake Bonneville during the last glaciation.

Information

Type
Research Article
Copyright
Elsevier B.V.

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Supplementary material: PDF

Refsnider et al. Supplementary Material

Supplementary Material

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