A climatic-limnologic model of diatom succession for paleolimnological interpretation of varved sediments at Elk Lake, Minnesota

1988 ◽  
Vol 1 (2) ◽  
Author(s):  
J. Platt Bradbury
Keyword(s):  
Varved Sediments ◽  
Elk Lake

Chrysophycean stomatocyst flora from Elk Lake, Clearwater County, Minnesota

1993 ◽  
Vol 71 (5) ◽  
pp. 737-756 ◽  
Author(s):  
Barbara A. Zeeb ◽  
John P. Smol
Keyword(s):  
Light Microscopy ◽  
Key Words ◽  
Working Group ◽  
Reference Site ◽  
Climatic Conditions ◽  
Varved Sediments ◽  
Electron And Light Microscopy ◽  
Interdisciplinary Effort ◽  
Elk Lake ◽  
Scanning Electron

The paleoecological record preserved in the varved sediments of Elk Lake, Clearwater County, Minnesota, has been used by a large number of researchers to reconstruct past environmental and climatic conditions that have occurred at this important reference site. As part of this interdisciplinary effort, we used the International Statospore Working Group (ISWG) taxonomic guidelines to describe the chrysophycean flora that Elk Lake supported over the last 10 400 years. In total, we identified 56 stomatocyst morphotypes using scanning electron and light microscopy. Over one-third of these morphotypes had not been previously recorded. Key words: stomatocyst, Chrysophyceae, paleolimnology, Minnesota, climatic change.

scholarly journals A long-term multi-proxy record of varved sediments highlights climate-induced mixing-regime shift in a large hard-water lake ~5000 years ago

2014 ◽  
Vol 73 (2) ◽  
Author(s):  
Walter Finsinger ◽  
Thierry Fonville ◽  
Emiliya Kirilova ◽  
Andrea Lami ◽  
Piero Guilizzoni ◽  
...  
Keyword(s):  
Regime Shift ◽  
Hard Water ◽  
Proxy Record ◽  
Varved Sediments ◽  
Water Lake ◽  
Mixing Regime

Eutrophication and recovery of Lake Vesij�rvi (south Finland): Diatom frustules in varved sediments over a 30-year period

Hydrobiologia ◽  
1993 ◽  
Vol 269-270 (1) ◽  
pp. 415-426 ◽  
Author(s):  
Mikko Liukkonen ◽  
Timo Kairesalo ◽  
Juha Keto
Keyword(s):  
Varved Sediments

scholarly journals VARDA (VArved sediments DAtabase) – providing and connecting proxy data from annually laminated lake sediments

2020 ◽  
Author(s):  
Arne Ramisch ◽  
Alexander Brauser ◽  
Mario Dorn ◽  
Cecile Blanchet ◽  
Brian Brademann ◽  
...  
Keyword(s):  
High Resolution ◽  
Lake Sediments ◽  
Climate Models ◽  
Detailed Comparison ◽  
High Temporal Resolution ◽  
Proxy Data ◽  
Varved Sediments ◽  
Proxy Records ◽  
Data Compilation ◽  
Varved Lake Sediments

Abstract. Varved lake sediments provide long climatic records with high temporal resolution and low associated age uncertainty. Robust and detailed comparison of well-dated and annually laminated sediment records is crucial for reconstructing abrupt and regionally time-transgressive changes as well as validation of spatial and temporal trajectories of past climatic changes. The VARved sediments DAtabase (VARDA) presented here is the first data compilation for varve chronologies and associated palaeoclimatic proxy records. The current version 1.0 allows detailed comparison of published varve records from 95 lakes. VARDA is freely accessible and was created to assess outputs from climate models with high-resolution terrestrial palaeoclimatic proxies. VARDA additionally provides a technical environment that enables to explore the database of varved lake sediments using a connected data-model and can generate a state-of-the-art graphic representation of multi-site comparison. This allows to reassess existing chronologies and tephra events to synchronize and compare even distant varved lake records. Furthermore, the present version of VARDA permits to explore varve thickness data. In this paper, we report in detail on the data mining and compilation strategies for the identification of varved lakes and assimilation of high-resolution chronologies as well as the technical infrastructure of the database. Additional paleoclimate proxy data will be provided in forthcoming updates. The VARDA graph-database and user interface can be accessed online at https://varve.gfz-potsdam.de, all datasets of version 1.0 are available at http://doi.org/10.5880/GFZ.4.3.2019.003 (Ramisch et al., 2019).

Multiple Dating of a Freeze Core from Lake 227, an Experimentally Fertilized Lake with Varved Sediments

1994 ◽  
Vol 51 (10) ◽  
pp. 2274-2285 ◽  
Author(s):  
Brent Wolfe ◽  
Hedy J. Kling ◽  
Gregg J. Brunskill ◽  
Paul Wilkinson
Keyword(s):  
Algal Blooms ◽  
Seasonal Abundance ◽  
Sedimentation Rates ◽  
Experimental Lakes Area ◽  
Varved Sediments ◽  
Varve Chronology ◽  
Freeze Core ◽  
N Loading ◽  
Planktonic Community

A freeze core taken from Experimental Lakes Area Lake 227 in 1988 contained 321 rhythmically paired, dark and light laminations in the upper 60.7 cm. Tape peels revealed cyclic, seasonal abundance peaks in organic and inorganic remains, which suggested that the couplets are varves. However, comparison between varve chronology and 22 yr of experimental changes in phosphorus (P) and nitrogen (N) loading and their influence on the planktonic community confirmed that the most recent varve-year estimates were 5 or 6 yr too old; this was caused by irregular sedimentation and multiple algal blooms resulting from experimental fertilization since 1969, and indistinct laminations that hampered precise couplet identification and separation. Dated horizons determined from biostratigraphic markers were used to generate compatible profiles between 1-cm slices of Lake 227 137Cs flux and reference fallout records. Nutrient concentration profiles were less helpful, as increases in carbon, N, and, P were gradual and no distinct horizon was identified as a clear marker of eutrophication. Long-term assessment of the varve chronology using 210Pb was hindered by experimental additions of 226Ra to the lake in 1970, although similar sedimentation rates from varve years 1860–1934 suggested that the varve and the deep part of the 210Pb chronologies were comparable.

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