Using Statistical Palynology to Describe Hydrologically-Controlled Variations in Plant Distribution in a Middle Eocene Wetland

Middle Eocene Claiborne Group lignites in western Kentucky overly clays that infill meander cut-offs in a paleofloodplain. In a Carlisle County, KY, deposit, the wedge-shaped lignite thins, becoming clay-rich toward the paleostream and thickens, becoming organic-rich toward the paleocutbank. This is similar to modern peat-forming wetlands in the region and on the Atlantic coastal plain. Palynomorphs preserved in the deposit record nine assemblages that can be roughly divided into gradational subsets of wet-tolerant and dry-tolerant clusters. Assemblage distributions are highly variable but follow a general trend of increasing wetness toward the paleostream. In general, repeating sequences of wet-tolerant assemblages followed by transitional to dry-tolerant assemblages occur throughout the deposit. Wet-tolerant assemblages can be correlated with flooding events that brought nutrient-rich clays into the deposit. Variations in which of the nine assemblages are present in a specific area reflect small-scale variations in depth to water-table in the system.