20 Lake Sediments as Archives of Environmental Change (Posters)

Sunday, 17 March 2019
1:30 PM - 5:30 PM
Casco Bay Hall

DO VARVES FORM IN SENECA LAKE, NY? USING A CALIBRATED FIVE-YEAR SEDIMENT TRAP RECORD TO RECONSTRUCT SEASONAL CLIMATE VARIABILITY DURING THE HOLOCENE

Paper number: 20-6
Program: Theme Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

Seneca Lake, a large, deep, temperate, warm monomictic lake located in western New York, preserves more than 12 m of post-glacial laminated sediment that spans the last 14,000 years. A time-sequencing sediment trap was deployed at 110 m water depth from 2009-2014 to measure the sediment export to the hypolimnion and evaluate the claim that the laminated sediment represents annual varves. Loss-on-ignition and X-ray diffraction analysis of sediment-trap samples and petrographic thin section analysis of freeze and piston cores were used to identify the seasonal sequence of sedimentation in the profundal zone. The weekly sediment-trap samples provided a high-resolution of measure of organic matter, calcium carbonate, and terrigenous fluxes to the lake bottom. Maximum total mass fluxes occurred during the isothermal mixing season (November-May) and this material was predominately quartz, followed by organic matter, muscovite and feldspar. Calcite-rich sediment dominated the flux during the stratified period (June-September). The five-year sediment trap dataset provides support for the claim that the alternating light-dark laminae observed in freeze, box and piston cores reflect two distinct seasons. High-resolution X-radiographs and μ-X-ray fluorescence of box and piston cores confirm the presence of two distinct, alternating laminae where the lighter colored laminae are dominated by calcium and the darker laminae by iron.

Geological Society of America Abstracts with Programs. Vol. 51, No. 1

doi: 10.1130/abs/2019NE-328191

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