Burial Lake in northwest Alaska records changes in water level and regional vegetation since ~39,000calyr BP based on terrestrial macrofossil AMS radiocarbon dates. A sedimentary unconformity is dated between 34,800 and 23,200calyr BP. During all or some of this period there was a hiatus in deposition indicating a major drop in lake level and deflation of lacustrine sediments. MIS 3 vegetation was herb-shrub tundra; more xeric graminoid-herb tundra developed after 23,200calyr BP. The tundra gradually became more mesic after 17,000calyr BP. Expansions of Salix then Betula, at 15,000 and 14,000calyr BP, respectively, are coincident with a major rise in lake level marked by increasing fine-grained sediment and higher organic matter content. Several sites in the region display disrupted sedimentation and probable hiatuses during the last glacial maximum (LGM); together regional data indicate an arid interval prior to and during the LGM and continued low moisture levels until ~15,000calyr BP. AMS 14C dates from Burial Lake are approximately synchronous with AMS 14C dates reported for the Betula expansion at nearby sites and sites across northern Alaska, but 1000-2000yr younger than bulk-sediment dates.
Bibliographical noteFunding Information:
Funding for this project was provided by the National Science Foundation—Earth System History . The pollen was processed and counted by Andrea Krumhardt at the University of Alaska, Fairbanks. We thank Paul Cutler and Gordon Macintosh for assistance in the field and Broxton Bird for the location map. The manuscript was greatly improved by the comments of two reviewers Daniel Mann and Nancy Bigelow.
Copyright 2011 Elsevier B.V., All rights reserved.
- Climate change
- Moisture balance
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