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A 40,000-yr record of environmental change from Burial Lake in Northwest Alaska |
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| Authors: | Mark B Abbott Mary E Edwards Bruce P Finney |
| Institution: | a Geology and Planetary Science, University of Pittsburgh, Room 200 SRCC Building, 4107 O'Hara Street, Pittsburgh, PA 15260, USA b School of Geography, University of Southampton, Highfield, Southampton SO17 1BJ, UK c Alaska Quaternary Center, Box 755940, University of Alaska Fairbanks, Fairbanks, AK 99775-5940, USA d Department of Biological Sciences, Idaho State University, Pocatello ID 83209, USA |
| Abstract: | Burial Lake in northwest Alaska records changes in water level and regional vegetation since ∼ 39,000 cal yr BP based on terrestrial macrofossil AMS radiocarbon dates. A sedimentary unconformity is dated between 34,800 and 23,200 cal yr 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 23,200 cal yr BP. The tundra gradually became more mesic after 17,000 cal yr BP. Expansions of Salix then Betula, at 15,000 and 14,000 cal yr 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 ∼ 15,000 cal yr 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 1000-2000 yr younger than bulk-sediment dates. |
| Keywords: | Alaska Late-Quaternary Climate change Aridity Lake-level Pollen Moisture balance |
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