24-4 High-resolution carbonate evidence for abrupt Early Holocene cooling in a western New York kettle pond

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

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Abstract:

Abrupt climate variability during the late deglacial and Early Holocene has been linked to freshwater discharge from Glacial Lake Agassiz to the Labrador Sea and associated disruptions to Atlantic Meridional Overturning Circulation, yet the expression of these events in the northeastern United States remains poorly constrained due to limited temporal resolution in some existing records. Small, shallow kettle lakes are well suited to resolving short-lived climate perturbations because they respond rapidly to environmental and climate drivers. Here we present a high-resolution carbonate-based warm-season temperature record from Round Pond, a small (surface area: 0.024 km²), shallow (maximum depth: 9.14 m) kettle pond in western New York, spanning ~13.5 to ~3.5 ka.

A 6.5-m-long sediment core recovered from the pond margin in 2023 preserves a continuous archive from late deglaciation to the present and records a lithostratigraphic succession from proglacial clay to laminated silt, sapropel, bedded to laminated carbonate-rich mud with abundant mollusks, and overlying peat. We conducted ITRAX X-ray fluorescence (XRF) scanning at a 0.5-mm resolution, loss-on-ignition analyses at 1–5 cm resolution, and mollusk assemblage analyses at 10-cm intervals. Carbonate content inferred from LOI is strongly correlated with XRF-derived Ca/Total ratios (r = 0.87), supporting the use of Ca/Total as a qualitative proxy for warm-season water temperature, although carbonate accumulation may also be influenced by changes in lake hydrology, alkalinity, or biological productivity. Variations in mollusk assemblages are consistent with inferred water temperature changes and support interpretation of the Ca/Total record as a temperature signal. We identified eight rapid decreases in carbonate content (by 5–25%) that broadly align with cooling signals in the Silver Lake (New Jersey) record and intervals of increased detrital carbonate flux in the Hudson Strait region, consistent with episodic freshwater forcing and provide new constraints on the regional expression of Early Holocene climate variability in the northeastern United States.

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