A 600-year-long record of environmental change inferred from varves, Ayr Lake, Baffin Island, Arctic Canada
MetadataShow full item record
A 600-yr-long varve record is developed from proglacial Ayr Lake, Baffin Island, Canada, (70°16'7.86"N, 70°37'1.70"W) to improve our understanding of the complex relationships between varve thickness and glacier and climate change. Varve thickness is compared to instrumental temperature and precipitation records from the weather station at Clyde River, 55 km to the east. No significant correlation with instrumental data is found; correlation coefficients range from 0.0004 to 0.09. Despite the lack of correlation between surface varves and the instrumental weather data, weak correlations exist between varve thickness and ice layer melt in ice cores from the Devon Ice Cap, and with a 2000-yr-long Arctic-wide temperature stack. In addition, a number of varve chronologies in the region were used to further interpret the Ayr Lake varve thickness chronology. Based on comparison with regional and Arctic-wide records, the Ayr Lake chronology was subdivided into three periods based on sedimentation rates and varve thickness variability. From 1435 to 1659 AD, glacial expansion combined with increased autumn precipitation and mild summer temperatures resulted in above average sedimentation rates. From 1660 to 1827 AD, glacial maximum extent combined with decreased autumn precipitation and cold summer temperatures resulted in below average sedimentation rates. From 1828 to 2004 AD, glacial retreat combined with increased autumn precipitation and warm summer temperatures resulted in above average sedimentation rates. In addition to higher sedimentation rates, high concentrations of ice-rafted debris between 1827 and 1911 AD may provide a complementary record for the timing of the initiation of glacial retreat. Evidence indicates that Ayr Lake sediments have a strong potential to provide the first sedimentary record of glacial retreat from their LIA maximum positions. However; the results of this study leave some questions unanswered for future work.