Palaeoecology of Late Cretaceous polar vegetation preserved in the Hansen Point Volcanics, NW Ellesmere Island, Canada

Mesozoic polar forests represent an extinct biome subject to a polar light regime and elevated atmospheric CO2 levels. In this paper, new Cretaceous fossil plant assemblages are reported from NW Ellesmere Island, Canada at a paleolatitude of 75°N. These occur in a Campanian–Maastrichtian-aged interval of the Hansen Point Volcanics, a unit interpreted as a coastal plain/peat mire complex within an active volcanic setting. Studies of palynomorphs, sterile and fertile foliage, and wood indicate that mire environments were dominated by amber-producing taxodiaceous conifers with other conifers, ginkgos, cycads, angiosperms, ferns, lycopsids, and bryophytes occurring in subordinate numbers. Leaf physiognomic studies imply that most vegetation was deciduous. Occurrence of traumatic rings in the woods, together with a high year-to-year variability in ring width, indicates disturbed growing conditions possibly linked to a combination of frosts, volcanic eruptions, and flooding. Abundant charcoal remains indicate that an additional important disturbance process was wildfire. Results of this study compare closely with those from coeval circum-Arctic fossil sites, and augment our knowledge of the community-scale ecology of the Cretaceous polar biome.