24-2 Assessing Late-Glacial Varve Presence and Environmental Controls in Western New York Lake Sediments

Session: Lake Sedimentary Records of Past Climate and Environment (Posters)

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Abstract:

Paleoenvironmental data from lake sediment records can be used to contextualize modern climate and environmental changes. One lake that can provide such information is Red Pond (42.133°N, 78.913°W), a meromictic kettle lake on the Last Glacial Maximum terminal moraine of the Laurentide Ice Sheet in western New York. We collected sediment cores using a Nesje-style percussion-piston coring system for the soft upper sediments and a manual GeoProbe percussion coring system for the stiff lower sediments. The sediment cores contain a unit of finely laminated (sub-millimeter) tan clayey sand at the base, with a transition to a unit of dark brown organic-rich sediment that persists to the top. An age-depth model based on 10 radiocarbon ages from terrestrial macrofossils indicates that the basin formed before 14.0 ± 0.2 cal ka BP and the transition from tan sand to dark brown silt occurred approximately 10.6 ± 0.4 cal ka BP.  Petrographic sediment thin sections show microscopic alternating layers of coarse silt and finer material in both the upper and lower sediments. In the upper sediment unit, the finer layers are opaque organic material, while in the lower sediment unit they are composed of finer clastic material with orange siderite (FeCO₃). In the lower sediment unit, we aim to count the couplets of coarse silt and fine clay with siderite to compare with the age range predicted by our age-depth model for the counted interval. Our interpretation of the mechanisms by which these layers may have been deposited will be informed by X-ray diffraction analyses of sediment composition at 10 different locations in the sediment core. We aim to assess whether these alternating layers were deposited annually, which could provide a precise chronology for other paleoenvironmental data and offer insight on the paleolimnologic processes in Red Pond in the early Holocene. This work will help elucidate paleoenvironmental conditions in western New York, with potential for comparison to other iron-rich anoxic lake environments in the modern day.

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