LATE PALEOZOIC PALYNOFACIES AND CLIMATE IN THE NORTH AMERICAN MIDCONTINENT

The Late Paleozoic is well established as a time of global climate change, with marked glacioeustatic fluctuations. Such fluctuations had notable influence on coastal areas, particularly on the equatorial, shallow inland sea that occupied what is now the North American Midcontinent. Cores from Oklahoma reveal Pennsylvanian cyclothems preserving shallow marine deposits to terrestrial paleosols, including coals. The overall trend in the Oklahoman cores across the Pennsylvanian-Permian boundary is toward progressively lower water availability (increased seasonality or aridity) and this trend has significant paleobotanical and paleoecological implications for terrestrial ecosystems.

Biogeographic and ecologic fluctuations may be recorded in the form of macrofossils and microfossils, but cores severely restrict macrofossil analysis. Additionally, the recovery of identifiable pollen and spores is controlled in part by depositional environment and climate. However, palynological sampling also yields significant amounts of debris in the form of wood, cuticle, amorphous matter, etc. By analyzing the relative abundance, size, and preservational condition of such debris in conjunction with the recovered palynoflora, a clearer picture of vegetation, depositional environments, and climate may be drawn.

We report the results of our investigation of cores taken in Osage and Kay Counties, Oklahoma. These cores are aligned roughly north to south, giving an approximate transect of the southern end of the Midcontinent Shelf. Together, these cores sample a stratigraphic interval including the Admire and Council Grove Groups. The Council Grove Group contains the Pennsylvanian-Permian boundary, found within the Red Eagle Limestone. This broad temporal span and narrow geographic distribution are conducive to understanding heterogeneity in the preserved record of vegetational and climate change. Samples taken from the cores have been analyzed for pollen, spore, and debris content in order to establish palynofacies patterns and genus-level diversity. Understanding the relation between these elements and lithology is key to reconstructing the dynamics of this system.