Long-term hydroclimatic variability in the southern Selwyn and Mackenzie Mountains, Northwest Territories, Canada

Mirror Lake, Northwest Territories (62° N, 128° W), is an isothermal, oligotrophic lake located within the southern Selwyn Mountains. A 550-year varve chronology developed from the sedimentary record reveals changing climatic influences on scales of decades to centuries. July temperature is the dominant control over varve formation, as indicated by comparison of the recent varve chronology and local meteorological data. Precipitation also influences varve sedimentation, particularly through the dampening effects of increased snowfall on glacier ablation.; A multi-proxy examination of the Mirror Lake catchment, using both the varve chronology and a local dendroclimatological record, supports the sedimentological interpretation that July temperature was the dominant influence on varve formation during at least two periods of the LIA. Mirror Lake is the second location to report a dominance of two silt unit varves and, as the presence of this structure indicates changing climatic influences on varve sedimentation and long-term climate shifts in the Mirror Lake area, identifying this varve type in future studies potentially may be useful for interpreting climate signals within the sedimentary record from proglacial lakes. (Abstract shortened by UMI.)...