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Early Holocene dune activity linked with final destruction of Glacial Lake Minong, eastern Upper Michigan, USA |
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| Authors: | Henry M Loope Walter L Loope Ronald J Goble Harry M Jol |
| Institution: | a Department of Geosciences, University of Nebraska-Lincoln, Lincoln, NE 68588, USA b U.S. Geological Survey, Munising, MI 49862, USA c Department of Environmental Sciences, University of Toledo, Toledo, OH 43606, USA d Department of Geography and Anthropology, University of Wisconsin-Eau Claire, Eau Claire, WI 54702, USA e Department of Geosciences, University of West Georgia, Carrollton, GA 30118, USA |
| Abstract: | The early Holocene final drainage of glacial Lake Minong is documented by 21 OSL ages on quartz sand from parabolic dunes and littoral terraces and one radiocarbon age from a lake sediment core adjacent to mapped paleoshorelines in interior eastern Upper Michigan. We employ a simple model wherein lake-level decline exposes unvegetated littoral sediment to deflation, resulting in dune building. Dunes formed subsequent to lake-level decline prior to stabilization by vegetation and provide minimum ages for lake-level decline. Optical ages range from 10.3 to 7.7 ka; 15 ages on dunes adjacent to the lowest Lake Minong shoreline suggest final water-level decline ∼ 9.1 ka. The clustering of optical ages from vertically separated dunes on both sides of the Nadoway-Gros Cap Barrier around 8.8 ka and a basal radiocarbon date behind the barrier (8120 ± 40 14C yr BP 9.1 cal ka BP]) support the hypothesis that the barrier was breached and the final lake-level drop to the Houghton Low occurred coincident with (1) high meltwater flux into the Superior basin and (2) an abrupt, negative shift in oxygen isotope values in Lake Huron. |
| Keywords: | Lake Minong dunes Upper Michigan Lake Superior lake level OSL vibracoring |
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