This study investigates long-chain alkenones (LCAs) and complementary sedimentary proxies to reconstruct Late Holocene hydroclimatic variability in Humboldt Lake, a closed-basin prairie lake in central Canada. Sediments from a 14 C-dated 176-cm core previously studied for fossil diatoms were analysed for LCA concentrations and distributions alongside total organic carbon (TOC), C:N atomic ratios, and XRF-derived elemental counts (Ti and Ca) to refine regional climate reconstructions spanning the past ~2000 years. Distinct temporal zones are evident, with low LCA abundances and elevated salinity during the Medieval Climate Anomaly (MCA, 900–1200 CE) and high LCA production and reduced salinity during the Little Ice Age (LIA, 1200–1900 CE), reflecting pronounced shifts between arid and pluvial regimes. Novel wavelet coherence analysis revealed strong, centennial-scale coupling (100–400 years) among biogeochemical and sedimentary proxies, indicating solar-modulated hydroclimatic oscillations superimposed on longer millennial trends. In-phase and anti-phase relationships between detrital (Ti), carbonate (Ca), and organic proxies suggest that prairie lake ecosystems respond to a combination of external forcing (changes in solar irradiance) and large-scale internal climate variability (ENSO–PDO–NAO), but with distinct temporal lags linked to internal lake conditions. These results highlight the sensitivity of prairie hydrology to relatively modest climatic perturbations and demonstrate the potential of integrated biomarker-geochemical approaches to resolve the mechanisms driving centennial-scale drought and wet phases across the northern Great Plains.
Cavazzin et al. (Fri,) studied this question.
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