Integration of Palynological and Sedimentological Data Using a Multivariate Approach

In the absence of plant macrofossils, palynological data provide important data for reconstructing local floral assemblages, while the study of sediments offers insight into the depositional history and physical environments under which the plants grew. Until now, integration of palynology with sedimentologicial variables has rarely been considered. Recently, high-resolution palynological and grain size analyses were performed on a two-meter thick siltstone unit located between two prominent coal seams representing Metasequoia-dominated swamp forests from the middle Eocene Buchanan Lake Formation at Napartulik, Axel Heiberg Island, Nunavut, Canada. The palynological analysis facilitated reconstruction of the local vegetation, documented temporal changes in the local vegetation mosaic, and illustrated successional processes and possible responses to climatic and environmental changes. The grain size analysis provided data on changes that were occurring in the sediment supply and hydrologic regime under which these sediments were deposited. To better understand whether the observed patterns in the pollen spectrum were occurring independently or tied to changes in the environmental conditions, the percent values of pollen and grain sizes throughout the section were analyzed using detrended correspondence analysis (DCA) and correlation analysis (CA). The results of the CA and DCA illustrated that some of the genera were positively correlated to specific grain sizes, suggesting that some of the changes observed in the palynoflora were related to changes in the hydrologic regime and the resultant sedimentary environment. Metasequoia and Glyptostrobus pollen were positively correlated with sandier sediments, while Larix and Tsuga were associated with more fine-grained sediments. These results suggest the observed vegetation changes in our study are related to changes in the hydrologic regime and sediment supply, and that the response to these changes occurred quickly. Moreover, such fine-scale multivariate analyses that combine sedimentological with palynological data indicate both paleoecological change and habitat preferences at the species level.