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Willem van der Bilt Lake sediments and organic geochemical paleotemperature proxies We plan to collect sediment cores from any accessible lakes as part of the SEES Expedition. We anticipate these sediment records will span approximately the past 10,000 years, and plan to date the cores using a combination of cryptotephra analysis and macrofossil radiocarbon dating. We will then produce paired, independent, high resolution paleotemperature records using novel organic geochemical proxies. The first is based on compounds called alkenones produced by haptophyte algae living in the lakes (the Uk37 index). Van der Bilt has successfully applied this proxy to lake records from NW Svalbard in the past (van der Bilt et al., 2018). We also plan to utilize a relatively new proxy based on bacterial membrane lipids known as branched glycerol dialkyl glycerol tetraethers (brGDGTs). The distribution of these compounds has been shown to relate to local air temperature, and they have been successfully applied to Arctic lake settings in the past (e.g. de Wet et al., 2016), though not on Svalbard to date.Additionally, the team of Wim Hoek is planning on reconstructing climate over the past 4,000 years using techniques that are complimentary but do not overlap with the proxies described above. We feel the generation of supporting datasets from the same lakes will increase the efficacy of our data and strengthen conclusions from both teams. |