A High-Resolution Palynological Analysis, Axel Heiberg Island, Canadian High Arctic

Abstract

A high-resolution sampling protocol was used to study the microflora from a two-meter thick siltstone unit located between two prominent coals representing Metasequoia-dominated swamp forests from the middle Eocene (ca. 45 million years old) Buchanan Lake Formation at Napartulik, Axel Heiberg Island, Nunavut, Canada. This detailed analysis facilitated the reconstruction of the local vegetation history and provided possible explanations for the changes seen in the local shifting vegetation patterns. These changes are likely due to two phenomena: environmental disturbances, such as flooding and/or climate change and floral succession. Members of the Pinaceae dominated the local flora at times when the area was relatively dry, whereas Metasequoia Miki was predominant when local environmental conditions were more mesic. The pollen data provide evidence of successional processes and suggest that the local vegetation responded to climatic and environmental changes. More importantly, the pollen data indicate that the local floodplain vegetation was part of a larger, dynamic floral mosaic within a regional polar broad-leaved deciduous forest community and that periods of prolonged environmental stasis were generally limited to the swamp forest communities. Two major fern spikes were identified in the sequence and large-scale flooding was identified as being the likely disturbance factor responsible for landscape level reorganization.