Hydrogen isotopes of lignin-methoxy groups from Neogene sub-fossil wood in the Canadian Arctic

The purpose of this study was to estimate Miocene and Pliocene climate conditions at Canadian Arctic sites using the stable isotope geochemistry of sub-fossil wood. Specifically, we measured the stable hydrogen isotope composition of lignin-methoxy (d2HLM) from sub-fossil wood specimens preserved in Miocene and Pliocene aged sedimentary deposits at several sites across the Canadian Arctic Archipelago – Banks Island, Prince Patrick Island, Meighen Island, Ellesmere Island and Bylot Island. The d2HLM measurements can be used to estimate the d2H of water (precipitation) used by the trees at the time they were alive. In high latitude regions, the d2H of precipitation is sensitive to air temperature and, therefore, sub-fossil d2HLM values from Miocene-Pliocene aged trees can be used to reconstruct Miocene-Pliocene climate conditions. These sites were targeted because fossil forest beds had been documented here in previous studies. Insights from this research inform our understanding of the Arctic climate system, including its sensitivity to past (and potentially future) changes in land-ocean-atmospheric boundary conditions. Ultimately, such datasets are needed to inform climate models that are being used to predict future changes in the Arctic.