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

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.