CHARACTERIZING SEDIMENT MINERALOGY FROM A UNIQUE WESTERN NEW YORK LAKE TO BETTER UNDERSTAND PALEOENVIRONMENTAL PROXY SUITABILITY

Lake sediment records can provide useful information about past climate dynamics, which informs our understanding of future climate change. To accurately reconstruct climate data from lakes, it is important to first understand the in-lake processes that affect sediment composition. To that end, we investigate a sediment core from 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. At depth, the lake water chemistry is dominated by iron, which may contribute to authigenic mineral formation. 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. From top to bottom, the sediment begins with finely laminated (sub-millimeter) dark brown organic-rich silt, and transitions to tan clayey sand at the base. An age-depth model based on 10 radiocarbon ages from macrofossils indicates that the basin formed before 14.0±0.2 cal ka BP (thousand calendar years before present, 1950) and the transition from tan sand to dark brown silt occurred approximately 10.6±0.4 cal ka BP. Siderite (FeCO₃), vivianite (Fe²⁺₃(PO₄)₂ · 8H₂O), and pyrite (FeS₂) are found in several locations within the sediment sequence. We report a record of how and when siderite was deposited in our lake sediment core to evaluate its potential as a paleoenvironmental proxy, and we attempt to discern between in-lake and diagenetic formation using smear slides. With our work we hope to better understand changes in lake chemistry and the processes that cause climate to be recorded by minerals in this unique lake system.