| Summary: | The northernmost known boreal forest from the Late Pliocene epoch is located in Quttinirpaaq National Park, Nunavut, Canada (81.5°N). The Pliocene epoch has attracted significant attention as a proxy for global climate change predicted for the 21st century. Tree ring analysis, in combination with isotope analysis of plant tissue (cellulose), has been used to determine ancient climate conditions during the time that the trees grew. In this study, we examine the tree ring width and ring width distribution from three preserved tree trunks (Betula and Picea) from this Arctic Pliocene forest deposit (Ekblaw A). Further, we examine the purity of alpha-hemicellulose extracted from these growth rings to detect the presence of metal oxides (FeO) in the extract using FTIR and SEM/EDX spectroscopy. The presence of FeO may compromise oxygen stable isotope analyses that are performed on alpha-hemicellulose. Results indicate that the trees from the Ekblaw A site grew slowly (mean ring width = 0.26 mm, range = 0.5mm–1.7mm). This growth rate is lower than those reported for other Arctic Pliocene sites. δ18O values of alpha-hemicellulose extracted from growth rings range from 11.48‰ VSMOW to 20.40‰ VSMOW. Some growth rings report δ18O values that are lower than those reported from other Arctic sites (mean = 19.5‰ VSMOW, range = 16.0‰ VSMOW-24‰ VSMOW). Examination of alpha-hemicellulose extracts indicates that no FeO is present in the samples and suggest that trees from the Ekblaw A site grew under different climate conditions than other Pliocene forests in the Arctic. NSF grant #1026177 No embargo
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