Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Entire DC Network
A 2200-Year Record Of Hydrologic Variability From Foy Lake, Montana, Usa, Inferred From Diatom And Geochemical Data, Lora R. Stevens, Jeffery R. Stone, Josh Campbell, Sherilyn C. Fritz
A 2200-Year Record Of Hydrologic Variability From Foy Lake, Montana, Usa, Inferred From Diatom And Geochemical Data, Lora R. Stevens, Jeffery R. Stone, Josh Campbell, Sherilyn C. Fritz
Department of Earth and Atmospheric Sciences: Faculty Publications
A 2200-yr long, high-resolution (~5 yr) record of drought variability in northwest Montana is inferred from diatoms and δ18O values of bio-induced carbonate preserved in a varved lacustrine core from Foy Lake. A previously developed model of the diatom response to lake-level fluctuations is used to constrain estimates of paleolake levels derived from the diatom data. High-frequency (decadal) fluctuations in the de-trended δ18O record mirror variations in wet/dry cycles inferred from Banff tree-rings, demonstrating the sensitivity of the oxygen-isotope values to changes in regional moisture balance. Low frequency (multi-centennial) isotopic changes may be associated with shifts …
Diatom Paleolimnological Record Of Holocene Climatic And Environmental Change In The Altai Mountains, Siberia, Karlyn S. Westover, Sherilyn C. Fritz, Tatyana A. Blyakharchuk, Herbert E. Wright
Diatom Paleolimnological Record Of Holocene Climatic And Environmental Change In The Altai Mountains, Siberia, Karlyn S. Westover, Sherilyn C. Fritz, Tatyana A. Blyakharchuk, Herbert E. Wright
Department of Earth and Atmospheric Sciences: Faculty Publications
The sedimentary diatom records of three shallow lakes in the Altai Mountains, southern Siberia, were examined to assess the nature and timing of Holocene environmental changes. Few paleoenvironmental records, especially reconstructions not based on pollen, have been reported from this region. The lakes differ in elevation, annual precipitation, and catchment vegetation. Diatom assemblages in all lakes were dominated for the entire period of record by small benthic species of Pseudostaurosira Williams & Round, Staurosira Ehrenberg, and Staurosirella Williams & Round. Planktonic taxa only occur in very low abundances (<5%). The most diverse diatom flora was found in Dzhangyskol, which is situated at the lowest elevation within a forested catchment. A lack of detailed information on the ecological preferences of the dominant taxa and the complexity of environmental drivers make direct interpretation of the diatom record difficult. However, other proxies suggest that dramatic shifts in dominance between Staurosira elliptica and Staurosirella pinnata in Grusha Ozero reflect millennial-scale variability …