PALYNOLOGICAL CORRELATION OF MISSISSIPPIAN STAGE BOUNDARIES

The adoption of the Mississippian and Pennsylvanian as subsystems of the Carboniferous and the consequent attempts to establish new (global) stages have drawn attention to the problems in correlating European and North American regional stage boundaries. The Western European Mississippian miospore zonation has recently been expanded and now comprises sixteen well-documented biozones and sub-biozones. In contrast, no zonal scheme exists for palynomorphs in this stratigraphic interval in the USA. Miospore assemblages are described from latest Famennian, Kinderhookian and Osagean sections in Missouri, Illinois, Ohio and Kentucky. Assemblages from the ‘type' Mississippian succession in the Mississippi dominance of carbonates through much of the sequence; coverage is better in the more clastic successions further east but independent calibration of the age of these sections is variable. In ascending order, the European Verrucosisporites nitidus, Cyrtospora cristifera, Spelaeotriletes balteatus and Spelaeotriletes pretiosus biozones have now been recognised in the latest Devonian and Mississippian of the Midwest USA, permitting correlation with Western Europe. In addition, new palynological evidence from in southern Ohio suggests that the Devonian / Carboniferous boundary is located within (or above) the Berea Sandstone, not as previously thought, within or at the base of the underlying Bedford Shale.