Synchronous climatic change inferred from diatom records in four western Montana lakes in the U.S. Rocky Mountains

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• 作者：Brandi Bracht-Flyr^a ; ^{brachtflyr@huskers.unl.edu} ; Sherilyn C. Fritz^a ; ^b ; ^{sfritz2@unl.edu}
• 关键词：Diatom ; Lake-level ; Paleoclimate ; Holocene ; western North America ; Little Ice Age ; Medieval Climate Anomaly
• 刊名：Quaternary Research
• 出版年：2012
• 期刊代码：97_00335894
• 类别：ear
• 出版时间：May, 2012
• 卷：77
• 期：3
• 页码：456-467
• 文件大小：1913 K

摘要

Late-Holocene environmental and climatic conditions were reconstructed from diatom assemblages in sediment cores from four western Montana lakes: Crevice Lake, Foy Lake, Morrison Lake, and Reservoir Lake. The lakes show synchroneity in timing of shifts in diatom community structure, but the nature of these changes differs among the lakes. Two of the sites provide highly resolved records of hydrologic balance, while the other two stratigraphic sequences primarily record temperature impact on lake thermal structure. All four lakes show significant change in five discrete intervals: 2200-2100, 1700-1600, 1350-1200, 800-600, and 250 cal yr BP. The similarities in the timing of change suggest overlying regional climatic influences on lake dynamics. The 800-600 cal yr BP shift is evident in other paleorecords throughout the Great Plains and western US, associated with the transition from the Medieval Climate Anomaly to the Little Ice Age. Large-scale climatic mechanisms that influence these lake environments may result from atmospheric circulation patterns that are driven by interactions between Pacific and Atlantic sea-surface temperatures, which are then locally modified by topography.