Influence of Climatic Trends and Cycles on Varve Deposition in Crawford Lake, Ontario, Canada

Varves accumulating below the chemocline of meromictic Crawford Lake, Milton, Ontario, Canada, consist dark-colored organic matter laminations that are primarily deposited during fall plankton die-off, alternating with light-colored comprising calcite crystals precipitated a relatively narrow water temperature and pH-controlled depositional window in summer. A novel high-resolution imaging protocol was used to photograph varve record 87 cm-long freeze core CRA19-2FT-B2, collected from deepest part (~23 m) lake February 2019. High-resolution images were to: (1) characterize couplets between AD 1870 2000 (chronology verified through 137Cs/210Pb analysis CRA22-1FRA-3, consistent historic nuclear fallout other proxies Great Acceleration); (2) document distinctive varves permit correlation cores throughout deep basin Lake; (3) measure thickness individual dark light- colored laminations, which found vary 0.04 mm 3.76 mm; (4) carry out wavelet spectral time series analyses based on data can be correlated climatic trends cycles. Time identified cycles statistically significant periodicities attributed Quasi-biennial Oscillation (2.3 years), El Niño Southern (2–7 11-year Schwabe Sunspot cycle possible Pacific Decadal (50–70 years). This research not only provides baseline chronostratigraphic allow subsampled for various proxies, but also documents dynamics climate drivers influence deposition both inorganically calcite. Lake is currently candidate site under consideration Global boundary Stratotype Section Point (GSSP) define Anthropocene series/epoch.