A previously unrecognized path of early Holocene base flow and elevated discharge from Lake Minong to Lake Chippewa across eastern Upper Michigan

GSA Special Papers
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Abstract

It has long been hypothesized that flux of fresh meltwater from glacial Lake Minong in North America's Superior Basin to the North Atlantic Ocean triggered rapid climatic shifts during the early Holocene. The spatial context of recent support for this idea demands a reevaluation of the exit point of meltwater from the Superior Basin. We used ground penetrating radar (GPR), foundation borings from six highway bridges, a GIS model of surface topography, geologic maps, U.S. Department of Agriculture–Natural Resources Conservation Service soils maps, and well logs to investigate the possible linkage of Lake Minong with Lake Chippewa in the Lake Michigan Basin across eastern Upper Michigan. GPR suggests that a connecting channel lies buried beneath the present interlake divide at Danaher. A single optical age hints that the channel aggraded to 225 m as elevated receipt of Lake Agassiz meltwater in the Superior Basin began to wane <10.6 ka. The large supply of sediment required to accommodate aggradation was immediately available at the channel's edge in the littoral shelves of abandoned Lake Algonquin and in distal parts of post-Algonquin fans. As discharge decreased further, the aggraded channel floor was quickly breached and interbasin flow to Lake Chippewa was restored. Basal radiocarbon ages on wood from small lakes along the discharge path and a GIS model of Minong's shoreline are consistent with another transgression of Minong after ca. 9.5 ka. At the peak of the latter transgression, the southeastern rim of the Superior Basin (Nadoway Drift Barrier) failed, ending Lake Minong. Upon Minong's final drop, aggradational sediments were deposited at Danaher, infilling the prior breach.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title A previously unrecognized path of early Holocene base flow and elevated discharge from Lake Minong to Lake Chippewa across eastern Upper Michigan
Series title GSA Special Papers
DOI 10.1130/2014.2508(01)
Volume 508
Year Published 2014
Language English
Publisher Geological Society of America
Contributing office(s) Great Lakes Science Center
Description 13 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title GSA Special Papers
First page 1
Last page 13
Country United States
State Michigan
Other Geospatial Lake Superior