Multiple generations of interglacial lake sediment preserved beneath the Laurentide Ice Sheet
- 1Department of Geology, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
- 2Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80303, and Department of Geology, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
- 3Department of Earth and Environmental Sciences, University of Illinois at Chicago, Chicago, Illinois 60607, USA
- 4Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado 80303, USA
- 5Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta AB T6G 2E3, Canada
Abstract
It is generally assumed that regions glaciated by continental ice sheets offer little promise for long paleoenvironmental records due to erosional processes associated with glaciation. We show that beneath portions of the northeastern Laurentide Ice Sheet, characterized by cold-based glaciation, sediment sequences representing multiple interglaciations have been preserved within extant lake basins. Radiocarbon and optically stimulated luminescence dating confirm the antiquity of the sediments, thereby extending the terrestrial paleoenvironmental record of the Canadian Arctic by hundreds of thousands of years. The lake sediment record presented here corroborates numerous recent cosmogenic exposure dating studies indicating complex patterns of erosion beneath polar ice sheets. It also demonstrates that the presence of intact interglacial sediments does not demand unglaciated refugia. Similarly ancient sediments may be preserved in many regions formerly covered by Pleistocene ice sheets.
- Arctic
- lake sediments
- Laurentide Ice Sheet
- cold-based ice
- glacier erosion
- paleoclimate
- interglaciation
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- Accepted 11 May 2007.
- Received 21 February 2007.
- Revision received 8 May 2007.
- The Geological Society of America, Inc.
