Varve formation during the past three centuries in three large proglacial lakes in south-central Alaska

Evelien Boes, Maarten Van Daele, Jasper Moernaut, Sabine Schmidt, Britta J.L. Jensen, Nore Praet, Darrell S Kaufman, Peter Haeussler, Michael G. Loso, Marc De Batist

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The sediments stored in the large, deep proglacial lakes of south-central Alaska are largely unstudied. We analyzed sediments in 20 cores, up to 160 cm long, from Eklutna, Kenai, and Skilak Lakes, using a combination of repeated lamination counting, radionuclide dating, event stratigraphy, and tephrochronology. We show that the characteristically rhythmic layers were deposited annually. Most of these glacial varves consist of one coarse-grained base and a fine-grained top, but varves composed of multiple coarsegrained turbidite pulses are common too. They are likely related to successive episodes of high sediment discharge during flooding, and they become more frequent in all three lakes, along with increased sedimentation rates, during the nineteenth century late phase of the Little Ice Age. These flood turbidites were generated by rain events and intense melting of snow and ice. Other (mega) turbidites are a result of earthquake-triggered slope collapses (e.g., A.D. 1964). Some event layers are present in all three lakes. In addition, the annual time series of varve thickness (normalized annual sedimentation rate) are significantly correlated among the three lakes (ρ > 0.27; p < 0.001). Differences between the varve thickness records can be attributed partly to the dam construction at Eklutna Lake and outbursts from an icedammed lake at Skilak Lake. Geomorphologic differences among the catchments result in further differences in sedimentation patterns in the three lakes.

Original languageEnglish (US)
Pages (from-to)757-774
Number of pages18
JournalBulletin of the Geological Society of America
Volume130
Issue number5-6
DOIs
StatePublished - May 1 2018

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varve
lake
sedimentation rate
event stratigraphy
sediment
tephrochronology
ice
dam construction
lamination
turbidite
nineteenth century
outburst
radionuclide
flooding
snow
melting
sedimentation
catchment
time series
earthquake

ASJC Scopus subject areas

  • Geology

Cite this

Boes, E., Van Daele, M., Moernaut, J., Schmidt, S., Jensen, B. J. L., Praet, N., ... De Batist, M. (2018). Varve formation during the past three centuries in three large proglacial lakes in south-central Alaska. Bulletin of the Geological Society of America, 130(5-6), 757-774. https://doi.org/10.1130/B31792.1

Varve formation during the past three centuries in three large proglacial lakes in south-central Alaska. / Boes, Evelien; Van Daele, Maarten; Moernaut, Jasper; Schmidt, Sabine; Jensen, Britta J.L.; Praet, Nore; Kaufman, Darrell S; Haeussler, Peter; Loso, Michael G.; De Batist, Marc.

In: Bulletin of the Geological Society of America, Vol. 130, No. 5-6, 01.05.2018, p. 757-774.

Research output: Contribution to journalArticle

Boes, E, Van Daele, M, Moernaut, J, Schmidt, S, Jensen, BJL, Praet, N, Kaufman, DS, Haeussler, P, Loso, MG & De Batist, M 2018, 'Varve formation during the past three centuries in three large proglacial lakes in south-central Alaska', Bulletin of the Geological Society of America, vol. 130, no. 5-6, pp. 757-774. https://doi.org/10.1130/B31792.1
Boes, Evelien ; Van Daele, Maarten ; Moernaut, Jasper ; Schmidt, Sabine ; Jensen, Britta J.L. ; Praet, Nore ; Kaufman, Darrell S ; Haeussler, Peter ; Loso, Michael G. ; De Batist, Marc. / Varve formation during the past three centuries in three large proglacial lakes in south-central Alaska. In: Bulletin of the Geological Society of America. 2018 ; Vol. 130, No. 5-6. pp. 757-774.
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