USING MULTIPLE SURFACE CORES TO TEST THE VARVE THICKNESS-SUMMER TEMPERATURE RELATIONSHIP, NORTHEAST BAFFIN ISLAND, ARCTIC CANADA

Understanding past climate change helps to place global warming in a long-term context and to better inform models of future change. Here, we use lake sediments from the Arctic, a region particularly sensitive to climate change, to reconstruct past climate. In 2006, a surface sediment core was obtained from the 36-m-deep basin of proglacial Big Round Lake, Arctic Canada. This sediment contains annually laminated couplets (varves), which are often used to reconstruct past climate. Some inconsistencies were noticed, however, when the 2006 varve thickness record was compared to nearby instrumental summer temperature records. In this study, we further test the varve thickness-summer temperature relationship by examining two surface cores obtained in 2007 from the deep basin adjacent to the 2006 core site. These additional cores will assist in understanding if diverse depositional environments in a single lake basin affect varve thickness and therefore affect the potential to use varve thickness as a proxy for summer temperature. We measured magnetic susceptibility and organic matter content (loss on-ignition) in the three cores. Initial results show similar trends between cores. The next step is to measure varve thickness in the 2007 cores and compare the resulting records to each other and to instrumental temperature records. The practice of analyzing one core as a general representative of an entire lake basin is supported by this research. Analysis of multiple cores from one lake, however, allows for a more detailed view of lake sedimentation, which can then be used to more accurately reconstruct past climate.