Palaeohydrology of the Southwest Yukon Territory, Canada, based on multiproxy analyses of lake sediment cores from a depth transect

被引:45
作者
Anderson, L
Abbott, MB
Finney, BP
Edwards, ME
机构
[1] Univ Massachusetts, Dept Geosci, Amherst, MA 01003 USA
[2] Univ Pittsburgh, Dept Geol & Planetary Sci, Pittsburgh, PA 15260 USA
[3] Univ Alaska, Inst Marine Sci, Fairbanks, AK 99775 USA
[4] Univ Alaska, Inst Arctic Biol, Fairbanks, AK 99775 USA
[5] Univ Southampton, Sch Geog, Southampton SO17 1BJ, Hants, England
关键词
lake-level; effective moisture; palaeoclimate; palaeolimnology; carbon isotopes; nitrogen isotopes; Yukon Territory; Canada; Holocene;
D O I
10.1191/0959683605hl889rp
中图分类号
P9 [自然地理学];
学科分类号
0705 ; 070501 ;
摘要
Lake-level variations at Marcella Lake, a small, hydrologically closed lake in the southwestern Yukon Territory, document changes in effective moisture since the early Holocene. Former water levels, driven by regional palaeohydrology, were reconstructed by multiproxy analyses of sediment cores from four sites spanning shallow to deep water. Marcella Lake today is thermally stratified, being protected from wind by its position in a depression. It is alkaline and undergoes bio-induced calcification. Relative accumulations of calcium carbonate and organic matter at the sediment-water interface depend on the location of the depositional site relative to the thermocline. We relate lake-level fluctuations to down-core stratigraphic variations in composition, geochemistry, sedimentary structures and to the occurrence of unconformities in four cores based on observations of modern limnology and sedimentation processes. Twenty-four AMS radiocarbon dates on macrofossils and pollen provide the lake-level chronology. Prior to 10 000 cal. BP water levels were low, but then they rose to 3 to 4 m below modern levels. Between 7500 and 5000 cal. BP water levels were 5 to 6 m below modern but rose by 4000 cal. BP. Between 4000 and 2000 cal. BP they were higher than modern. During the last 2000 years, water levels were either near or 1 to 2 m below modern levels. Marcella Lake water-level fluctuations correspond with previously documented palaeoenvironmental and palaeoclimatic changes and provide new, independent effective moisture information. The improved geochronology and quantitative water-level estimates are a framework for more detailed studies in the southwest Yukon.
引用
收藏
页码:1172 / 1183
页数:12
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